/* -*- Mode: C; tab-width: 4; c-file-style: "bsd"; c-basic-offset: 4; fill-column: 108; indent-tabs-mode: nil; -*-
*
* Copyright (c) 2002-2024 Apple Inc. All rights reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef STANDALONE
// Set mDNS_InstantiateInlines to tell mDNSEmbeddedAPI.h to instantiate inline functions, if necessary
#define mDNS_InstantiateInlines 1
#include "DNSCommon.h"
#include "DebugServices.h"
#if MDNSRESPONDER_SUPPORTS(COMMON, LOCAL_DNS_RESOLVER_DISCOVERY)
#include "discover_resolver.h"
#endif
#if MDNSRESPONDER_SUPPORTS(APPLE, DNS_PUSH)
#include "dns_push_discovery.h"
#endif
#if MDNSRESPONDER_SUPPORTS(APPLE, DNSSECv2)
#include "dnssec_obj_rr_ds.h" // For dnssec_obj_rr_ds_t.
#include "dnssec_mdns_core.h" // For DNSSEC-related operation on mDNSCore structures.
#include "rdata_parser.h" // For DNSSEC-related records parsing.
#include "base_encoding.h" // For base64 encoding.
#endif
#if MDNSRESPONDER_SUPPORTS(APPLE, OS_UNFAIR_LOCK)
#include <os/lock.h> // For os_unfair_lock.
#endif
#if MDNSRESPONDER_SUPPORTS(APPLE, LOG_PRIVACY_LEVEL)
#include "system_utilities.h" //For is_apple_internal_build().
#endif
// Disable certain benign warnings with Microsoft compilers
#if (defined(_MSC_VER))
// Disable "conditional expression is constant" warning for debug macros.
// Otherwise, this generates warnings for the perfectly natural construct "while(1)"
// If someone knows a variant way of writing "while(1)" that doesn't generate warning messages, please let us know
#pragma warning(disable:4127)
// Disable "array is too small to include a terminating null character" warning
// -- domain labels have an initial length byte, not a terminating null character
#pragma warning(disable:4295)
#endif
// ***************************************************************************
// MARK: - Program Constants
#include "mdns_strict.h"
mDNSexport const mDNSInterfaceID mDNSInterface_Any = 0;
mDNSexport const mDNSInterfaceID mDNSInterfaceMark = (mDNSInterfaceID)-1;
mDNSexport const mDNSInterfaceID mDNSInterface_LocalOnly = (mDNSInterfaceID)-2;
mDNSexport const mDNSInterfaceID mDNSInterface_P2P = (mDNSInterfaceID)-3;
mDNSexport const mDNSInterfaceID uDNSInterfaceMark = (mDNSInterfaceID)-4;
mDNSexport const mDNSInterfaceID mDNSInterface_BLE = (mDNSInterfaceID)-5;
// Note: Microsoft's proposed "Link Local Multicast Name Resolution Protocol" (LLMNR) is essentially a limited version of
// Multicast DNS, using the same packet formats, naming syntax, and record types as Multicast DNS, but on a different UDP
// port and multicast address, which means it won't interoperate with the existing installed base of Multicast DNS responders.
// LLMNR uses IPv4 multicast address 224.0.0.252, IPv6 multicast address FF02::0001:0003, and UDP port 5355.
// Uncomment the appropriate lines below to build a special Multicast DNS responder for testing interoperability
// with Microsoft's LLMNR client code.
#define DiscardPortAsNumber 9
#define SSHPortAsNumber 22
#define UnicastDNSPortAsNumber 53
#define SSDPPortAsNumber 1900
#define IPSECPortAsNumber 4500
#define NSIPCPortAsNumber 5030 // Port used for dnsextd to talk to local nameserver bound to loopback
#define NATPMPAnnouncementPortAsNumber 5350
#define NATPMPPortAsNumber 5351
#define DNSEXTPortAsNumber 5352 // Port used for end-to-end DNS operations like LLQ, Updates with Leases, etc.
#define MulticastDNSPortAsNumber 5353
#define LoopbackIPCPortAsNumber 5354
//#define MulticastDNSPortAsNumber 5355 // LLMNR
#define PrivateDNSPortAsNumber 5533
mDNSexport const mDNSIPPort DiscardPort = { { DiscardPortAsNumber >> 8, DiscardPortAsNumber & 0xFF } };
mDNSexport const mDNSIPPort SSHPort = { { SSHPortAsNumber >> 8, SSHPortAsNumber & 0xFF } };
mDNSexport const mDNSIPPort UnicastDNSPort = { { UnicastDNSPortAsNumber >> 8, UnicastDNSPortAsNumber & 0xFF } };
mDNSexport const mDNSIPPort SSDPPort = { { SSDPPortAsNumber >> 8, SSDPPortAsNumber & 0xFF } };
mDNSexport const mDNSIPPort IPSECPort = { { IPSECPortAsNumber >> 8, IPSECPortAsNumber & 0xFF } };
mDNSexport const mDNSIPPort NSIPCPort = { { NSIPCPortAsNumber >> 8, NSIPCPortAsNumber & 0xFF } };
mDNSexport const mDNSIPPort NATPMPAnnouncementPort = { { NATPMPAnnouncementPortAsNumber >> 8, NATPMPAnnouncementPortAsNumber & 0xFF } };
mDNSexport const mDNSIPPort NATPMPPort = { { NATPMPPortAsNumber >> 8, NATPMPPortAsNumber & 0xFF } };
mDNSexport const mDNSIPPort DNSEXTPort = { { DNSEXTPortAsNumber >> 8, DNSEXTPortAsNumber & 0xFF } };
mDNSexport const mDNSIPPort MulticastDNSPort = { { MulticastDNSPortAsNumber >> 8, MulticastDNSPortAsNumber & 0xFF } };
mDNSexport const mDNSIPPort LoopbackIPCPort = { { LoopbackIPCPortAsNumber >> 8, LoopbackIPCPortAsNumber & 0xFF } };
mDNSexport const mDNSIPPort PrivateDNSPort = { { PrivateDNSPortAsNumber >> 8, PrivateDNSPortAsNumber & 0xFF } };
mDNSexport const OwnerOptData zeroOwner = { 0, 0, { { 0 } }, { { 0 } }, { { 0 } } };
mDNSexport const mDNSIPPort zeroIPPort = { { 0 } };
mDNSexport const mDNSv4Addr zerov4Addr = { { 0 } };
mDNSexport const mDNSv6Addr zerov6Addr = { { 0 } };
mDNSexport const mDNSEthAddr zeroEthAddr = { { 0 } };
mDNSexport const mDNSv4Addr onesIPv4Addr = { { 255, 255, 255, 255 } };
mDNSexport const mDNSv6Addr onesIPv6Addr = { { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 } };
mDNSexport const mDNSEthAddr onesEthAddr = { { 255, 255, 255, 255, 255, 255 } };
mDNSexport const mDNSAddr zeroAddr = { mDNSAddrType_None, {{{ 0 }}} };
mDNSexport const mDNSv4Addr AllDNSAdminGroup = { { 239, 255, 255, 251 } };
mDNSexport const mDNSv4Addr AllHosts_v4 = { { 224, 0, 0, 1 } }; // For NAT-PMP & PCP Annoucements
mDNSexport const mDNSv6Addr AllHosts_v6 = { { 0xFF,0x02,0x00,0x00, 0x00,0x00,0x00,0x00, 0x00,0x00,0x00,0x00, 0x00,0x00,0x00,0x01 } };
mDNSexport const mDNSv6Addr NDP_prefix = { { 0xFF,0x02,0x00,0x00, 0x00,0x00,0x00,0x00, 0x00,0x00,0x00,0x01, 0xFF,0x00,0x00,0xFB } }; // FF02:0:0:0:0:1:FF00::/104
mDNSexport const mDNSEthAddr AllHosts_v6_Eth = { { 0x33, 0x33, 0x00, 0x00, 0x00, 0x01 } };
mDNSexport const mDNSAddr AllDNSLinkGroup_v4 = { mDNSAddrType_IPv4, { { { 224, 0, 0, 251 } } } };
//mDNSexport const mDNSAddr AllDNSLinkGroup_v4 = { mDNSAddrType_IPv4, { { { 224, 0, 0, 252 } } } }; // LLMNR
mDNSexport const mDNSAddr AllDNSLinkGroup_v6 = { mDNSAddrType_IPv6, { { { 0xFF,0x02,0x00,0x00, 0x00,0x00,0x00,0x00, 0x00,0x00,0x00,0x00, 0x00,0x00,0x00,0xFB } } } };
//mDNSexport const mDNSAddr AllDNSLinkGroup_v6 = { mDNSAddrType_IPv6, { { { 0xFF,0x02,0x00,0x00, 0x00,0x00,0x00,0x00, 0x00,0x00,0x00,0x00, 0x00,0x01,0x00,0x03 } } } }; // LLMNR
mDNSexport const mDNSOpaque16 zeroID = { { 0, 0 } };
mDNSexport const mDNSOpaque16 onesID = { { 255, 255 } };
mDNSexport const mDNSOpaque16 QueryFlags = { { kDNSFlag0_QR_Query | kDNSFlag0_OP_StdQuery, 0 } };
mDNSexport const mDNSOpaque16 uQueryFlags = { { kDNSFlag0_QR_Query | kDNSFlag0_OP_StdQuery | kDNSFlag0_RD, 0 } };
mDNSexport const mDNSOpaque16 ResponseFlags = { { kDNSFlag0_QR_Response | kDNSFlag0_OP_StdQuery | kDNSFlag0_AA, 0 } };
mDNSexport const mDNSOpaque16 UpdateReqFlags = { { kDNSFlag0_QR_Query | kDNSFlag0_OP_Update, 0 } };
mDNSexport const mDNSOpaque16 UpdateRespFlags = { { kDNSFlag0_QR_Response | kDNSFlag0_OP_Update, 0 } };
mDNSexport const mDNSOpaque64 zeroOpaque64 = { { 0 } };
mDNSexport const mDNSOpaque128 zeroOpaque128 = { { 0 } };
extern mDNS mDNSStorage;
// ***************************************************************************
// MARK: - General Utility Functions
mDNSexport void CacheRecordSetResponseFlags(CacheRecord *const cr, const mDNSOpaque16 responseFlags)
{
cr->responseFlags = responseFlags;
cr->resrec.rcode = cr->responseFlags.b[1] & kDNSFlag1_RC_Mask;
}
mDNSexport void mDNSCoreResetRecord(mDNS *const m)
{
m->rec.r.resrec.RecordType = 0; // Clear RecordType to show we're not still using it
CacheRecordSetResponseFlags(&m->rec.r, zeroID);
#if MDNSRESPONDER_SUPPORTS(APPLE, DNSSECv2)
MDNS_DISPOSE_DNSSEC_OBJ(m->rec.r.resrec.dnssec);
#endif
}
// return true for RFC1918 private addresses
mDNSexport mDNSBool mDNSv4AddrIsRFC1918(const mDNSv4Addr * const addr)
{
return ((addr->b[0] == 10) || // 10/8 prefix
(addr->b[0] == 172 && (addr->b[1] & 0xF0) == 16) || // 172.16/12
(addr->b[0] == 192 && addr->b[1] == 168)); // 192.168/16
}
mDNSexport const char *DNSScopeToString(mDNSu32 scope)
{
switch (scope)
{
case kScopeNone:
return "Unscoped";
case kScopeInterfaceID:
return "InterfaceScoped";
case kScopeServiceID:
return "ServiceScoped";
default:
return "Unknown";
}
}
mDNSexport void mDNSAddrMapIPv4toIPv6(mDNSv4Addr* in, mDNSv6Addr* out)
{
out->l[0] = 0;
out->l[1] = 0;
out->w[4] = 0;
out->w[5] = 0xffff;
out->b[12] = in->b[0];
out->b[13] = in->b[1];
out->b[14] = in->b[2];
out->b[15] = in->b[3];
}
mDNSexport mDNSBool mDNSAddrIPv4FromMappedIPv6(mDNSv6Addr *in, mDNSv4Addr* out)
{
if (in->l[0] != 0 || in->l[1] != 0 || in->w[4] != 0 || in->w[5] != 0xffff)
return mDNSfalse;
out->NotAnInteger = in->l[3];
return mDNStrue;
}
NetworkInterfaceInfo *FirstInterfaceForID(mDNS *const m, const mDNSInterfaceID InterfaceID)
{
NetworkInterfaceInfo *intf = m->HostInterfaces;
while (intf && intf->InterfaceID != InterfaceID) intf = intf->next;
return(intf);
}
NetworkInterfaceInfo *FirstIPv4LLInterfaceForID(mDNS *const m, const mDNSInterfaceID InterfaceID)
{
NetworkInterfaceInfo *intf;
if (!InterfaceID)
return mDNSNULL;
// Note: We don't check for InterfaceActive, as the active interface could be IPv6 and
// we still want to find the first IPv4 Link-Local interface
for (intf = m->HostInterfaces; intf; intf = intf->next)
{
if (intf->InterfaceID == InterfaceID &&
intf->ip.type == mDNSAddrType_IPv4 && mDNSv4AddressIsLinkLocal(&intf->ip.ip.v4))
{
debugf("FirstIPv4LLInterfaceForID: found LL interface with address %.4a", &intf->ip.ip.v4);
return intf;
}
}
return (mDNSNULL);
}
mDNSexport char *InterfaceNameForID(mDNS *const m, const mDNSInterfaceID InterfaceID)
{
NetworkInterfaceInfo *intf = FirstInterfaceForID(m, InterfaceID);
return(intf ? intf->ifname : mDNSNULL);
}
mDNSexport const char *InterfaceNameForIDOrEmptyString(const mDNSInterfaceID InterfaceID)
{
const char *const ifName = InterfaceNameForID(&mDNSStorage, InterfaceID);
return (ifName ? ifName : "");
}
mDNSexport NetworkInterfaceInfo *GetFirstActiveInterface(NetworkInterfaceInfo *intf)
{
while (intf && !intf->InterfaceActive) intf = intf->next;
return(intf);
}
mDNSexport mDNSInterfaceID GetNextActiveInterfaceID(const NetworkInterfaceInfo *intf)
{
const NetworkInterfaceInfo *next = GetFirstActiveInterface(intf->next);
if (next) return(next->InterfaceID);else return(mDNSNULL);
}
mDNSexport mDNSu32 NumCacheRecordsForInterfaceID(const mDNS *const m, mDNSInterfaceID id)
{
mDNSu32 slot, used = 0;
CacheGroup *cg;
const CacheRecord *rr;
FORALL_CACHERECORDS(slot, cg, rr)
{
if (rr->resrec.InterfaceID == id)
used++;
}
return(used);
}
mDNSexport char *DNSTypeName(mDNSu16 rrtype)
{
switch (rrtype)
{
case kDNSType_A: return("Addr");
case kDNSType_NS: return("NS");
case kDNSType_CNAME: return("CNAME");
case kDNSType_SOA: return("SOA");
case kDNSType_NULL: return("NULL");
case kDNSType_PTR: return("PTR");
case kDNSType_HINFO: return("HINFO");
case kDNSType_TXT: return("TXT");
case kDNSType_AAAA: return("AAAA");
case kDNSType_SRV: return("SRV");
case kDNSType_OPT: return("OPT");
case kDNSType_NSEC: return("NSEC");
case kDNSType_NSEC3: return("NSEC3");
case kDNSType_NSEC3PARAM: return("NSEC3PARAM");
case kDNSType_TSIG: return("TSIG");
case kDNSType_RRSIG: return("RRSIG");
case kDNSType_DNSKEY: return("DNSKEY");
case kDNSType_DS: return("DS");
case kDNSType_SVCB: return("SVCB");
case kDNSType_HTTPS: return("HTTPS");
case kDNSType_TSR: return("TSR");
case kDNSQType_ANY: return("ANY");
default: {
static char buffer[16];
mDNS_snprintf(buffer, sizeof(buffer), "TYPE%d", rrtype);
return(buffer);
}
}
}
mDNSexport const char *mStatusDescription(mStatus error)
{
const char *error_description;
switch (error) {
case mStatus_NoError:
error_description = "mStatus_NoError";
break;
case mStatus_BadParamErr:
error_description = "mStatus_BadParamErr";
break;
default:
error_description = "mStatus_UnknownDescription";
break;
}
return error_description;
}
mDNSexport mDNSu32 swap32(mDNSu32 x)
{
mDNSu8 *ptr = (mDNSu8 *)&x;
return (mDNSu32)((mDNSu32)ptr[0] << 24 | (mDNSu32)ptr[1] << 16 | (mDNSu32)ptr[2] << 8 | ptr[3]);
}
mDNSexport mDNSu16 swap16(mDNSu16 x)
{
mDNSu8 *ptr = (mDNSu8 *)&x;
return (mDNSu16)((mDNSu16)ptr[0] << 8 | ptr[1]);
}
mDNSlocal void PrintTypeBitmap(const mDNSu8 *bmap, int bitmaplen, char *const buffer, mDNSu32 length)
{
int win, wlen, type;
while (bitmaplen > 0)
{
int i;
if (bitmaplen < 3)
{
LogMsg("PrintTypeBitmap: malformed bitmap, bitmaplen %d short", bitmaplen);
break;
}
win = *bmap++;
wlen = *bmap++;
bitmaplen -= 2;
if (bitmaplen < wlen || wlen < 1 || wlen > 32)
{
LogInfo("PrintTypeBitmap: malformed nsec, bitmaplen %d wlen %d", bitmaplen, wlen);
break;
}
if (win < 0 || win >= 256)
{
LogInfo("PrintTypeBitmap: malformed nsec, bad window win %d", win);
break;
}
type = win * 256;
for (i = 0; i < wlen * 8; i++)
{
if (bmap[i>>3] & (128 >> (i&7)))
length += mDNS_snprintf(buffer+length, (MaxMsg - 1) - length, "%s ", DNSTypeName(type + i));
}
bmap += wlen;
bitmaplen -= wlen;
}
}
#define TXT_RECORD_SEPARATOR '|'
mDNSlocal mDNSu8 mDNSLengthOfFirstUTF8Character(const mDNSu8 *bytes, mDNSu32 len);
mDNSlocal const mDNSu8 *mDNSLocateFirstByteToEscape(const mDNSu8 *const bytes, const mDNSu32 bytesLen)
{
for (const mDNSu8 *ptr = bytes, *const end = bytes + bytesLen; ptr < end;)
{
const mDNSu8 utf8CharacterLen = mDNSLengthOfFirstUTF8Character(ptr, (mDNSu32)(end - ptr));
if (utf8CharacterLen == 0)
{
return ptr;
}
else if (utf8CharacterLen == 1)
{
const char ch = *ptr;
if ((ch == '\\') || (ch == TXT_RECORD_SEPARATOR) || !mDNSIsPrintASCII(ch))
{
return ptr;
}
}
ptr += utf8CharacterLen;
}
return mDNSNULL;
}
mDNSlocal mDNSu32 putTXTRRCharacterString(char *const buffer, const mDNSu32 bufferLen, const mDNSu8 *const bytes,
const mDNSu32 bytesLen, const mDNSBool addSeparator, mDNSBool *const outTruncated)
{
mDNSBool truncated = mDNSfalse;
mDNSu32 nWrites = 0;
if (addSeparator)
{
require_action_quiet(bufferLen > 1, exit, truncated = mDNStrue);
nWrites = mDNS_snprintf(buffer, bufferLen, "%c", TXT_RECORD_SEPARATOR);
}
for (const mDNSu8 *ptr = bytes, *const end = bytes + bytesLen; ptr < end;)
{
const mDNSu32 remainingLen = (mDNSu32)(end - ptr);
const mDNSu8 *const firstByteToEscape = mDNSLocateFirstByteToEscape(ptr, remainingLen);
// [ptr ... firstByteToEscape ... end]
// The bytes between [ptr, firstByteToEscape) are directly-printable.
const mDNSu32 normalBytesLenToPrint = (firstByteToEscape ? ((mDNSu32)(firstByteToEscape - ptr)) : remainingLen);
// Print UTF-8 characters in [ptr, firstByteToEscape).
if (normalBytesLenToPrint > 0)
{
const mDNSu32 currentNWrites = mDNS_snprintf(buffer + nWrites, bufferLen - nWrites, "%.*s",
normalBytesLenToPrint, ptr);
nWrites += currentNWrites;
require_action_quiet(currentNWrites == normalBytesLenToPrint, exit, truncated = mDNStrue);
}
if (firstByteToEscape)
{
// Print the *firstByteToEscape if it exists.
const mDNSu8 byteToEscape = *firstByteToEscape;
if ((byteToEscape == '\\') || (byteToEscape == TXT_RECORD_SEPARATOR))
{
// One escape character `\\`, one character being escaped, one `\0`.
require_action_quiet((bufferLen - nWrites) >= 3, exit, truncated = mDNStrue);
nWrites += mDNS_snprintf(buffer + nWrites, bufferLen - nWrites, "\\%c", byteToEscape);
}
else
{
// Two-byte hex prefix `\\x`, Two-byte hex value "HH" , one '\0'.
require_action_quiet((bufferLen - nWrites) >= 5, exit, truncated = mDNStrue);
nWrites += mDNS_snprintf(buffer + nWrites, bufferLen - nWrites, "\\x%02X", byteToEscape);
}
ptr = firstByteToEscape + 1;
}
else
{
// firstByteToEscape is NULL means that the remaining characters are printable.
ptr += remainingLen;
}
}
exit:
if (outTruncated)
{
*outTruncated = truncated;
}
return nWrites;
}
mDNSlocal char *GetTXTRRDisplayString(const mDNSu8 *const rdata, const mDNSu32 rdLen, char *const buffer,
const mDNSu32 bufferLen)
{
mDNSu32 currentLen = 0;
#define RESERVED_BUFFER_LENGTH 5 // " <C>", " <T>" or " <M>" plus '\0'
require_quiet(bufferLen >= RESERVED_BUFFER_LENGTH, exit);
mDNSu32 adjustedBufferLen = bufferLen - RESERVED_BUFFER_LENGTH;
mDNSu32 characterStringLen;
mDNSBool malformed = mDNSfalse;
mDNSBool truncated = mDNSfalse;
mDNSBool addSeparator = mDNSfalse;
for (const mDNSu8 *src = rdata, *const end = rdata + rdLen; src < end && !truncated; src += characterStringLen)
{
characterStringLen = *src++;
if (((mDNSu32)(end - src)) < characterStringLen)
{
malformed = mDNStrue;
break;
}
currentLen += putTXTRRCharacterString((buffer + currentLen), (adjustedBufferLen - currentLen), src,
characterStringLen, addSeparator, &truncated);
addSeparator = mDNStrue;
}
const char statusCode = (malformed ? 'M' : (truncated ? 'T' : 'C'));
currentLen += mDNS_snprintf((buffer + currentLen), (bufferLen - currentLen), " <%c>", statusCode);
exit:
return buffer + currentLen;
}
// Note slight bug: this code uses the rdlength from the ResourceRecord object, to display
// the rdata from the RDataBody object. Sometimes this could be the wrong length -- but as
// long as this routine is only used for debugging messages, it probably isn't a big problem.
mDNSexport char *GetRRDisplayString_rdb(const ResourceRecord *const rr, const RDataBody *const rd1, char *const buffer)
{
const RDataBody2 *const rd = (const RDataBody2 *)rd1;
#define RemSpc (MaxMsg-1-length)
char *ptr = buffer;
mDNSu32 length = mDNS_snprintf(buffer, MaxMsg-1, "%4d %##s %s ", rr->rdlength, rr->name->c, DNSTypeName(rr->rrtype));
if (rr->RecordType == kDNSRecordTypePacketNegative) return(buffer);
if (!rr->rdlength && rr->rrtype != kDNSType_OPT) { mDNS_snprintf(buffer+length, RemSpc, "<< ZERO RDATA LENGTH >>"); return(buffer); }
switch (rr->rrtype)
{
case kDNSType_A: mDNS_snprintf(buffer+length, RemSpc, "%.4a", &rd->ipv4); break;
case kDNSType_NS: // Same as PTR
case kDNSType_CNAME: // Same as PTR
case kDNSType_PTR: mDNS_snprintf(buffer+length, RemSpc, "%##s", rd->name.c); break;
case kDNSType_SOA: mDNS_snprintf(buffer+length, RemSpc, "%##s %##s %d %d %d %d %d",
rd->soa.mname.c, rd->soa.rname.c,
rd->soa.serial, rd->soa.refresh, rd->soa.retry, rd->soa.expire, rd->soa.min);
break;
case kDNSType_HINFO: // Display this the same as TXT (show all constituent strings)
case kDNSType_TXT:
GetTXTRRDisplayString(rd->txt.c, rr->rdlength, buffer + length, RemSpc);
break;
case kDNSType_AAAA: mDNS_snprintf(buffer+length, RemSpc, "%.16a", &rd->ipv6); break;
case kDNSType_SRV: mDNS_snprintf(buffer+length, RemSpc, "%u %u %u %##s",
rd->srv.priority, rd->srv.weight, mDNSVal16(rd->srv.port), rd->srv.target.c); break;
case kDNSType_TSR: mDNS_snprintf(buffer+length, RemSpc, "%d", rd1->tsr_value); break;
case kDNSType_OPT: {
const rdataOPT *opt;
const rdataOPT *const end = (const rdataOPT *)&rd->data[rr->rdlength];
length += mDNS_snprintf(buffer+length, RemSpc, "Max %d", rr->rrclass);
for (opt = &rd->opt[0]; opt < end; opt++)
{
switch(opt->opt)
{
case kDNSOpt_LLQ:
length += mDNS_snprintf(buffer+length, RemSpc, " LLQ");
length += mDNS_snprintf(buffer+length, RemSpc, " Vers %d", opt->u.llq.vers);
length += mDNS_snprintf(buffer+length, RemSpc, " Op %d", opt->u.llq.llqOp);
length += mDNS_snprintf(buffer+length, RemSpc, " Err/Port %d", opt->u.llq.err);
length += mDNS_snprintf(buffer+length, RemSpc, " ID %08X%08X", opt->u.llq.id.l[0], opt->u.llq.id.l[1]);
length += mDNS_snprintf(buffer+length, RemSpc, " Lease %d", opt->u.llq.llqlease);
break;
case kDNSOpt_Lease:
length += mDNS_snprintf(buffer+length, RemSpc, " Lease %d", opt->u.updatelease);
break;
case kDNSOpt_Owner:
length += mDNS_snprintf(buffer+length, RemSpc, " Owner");
length += mDNS_snprintf(buffer+length, RemSpc, " Vers %d", opt->u.owner.vers);
length += mDNS_snprintf(buffer+length, RemSpc, " Seq %3d", (mDNSu8)opt->u.owner.seq); // Display as unsigned
length += mDNS_snprintf(buffer+length, RemSpc, " MAC %.6a", opt->u.owner.HMAC.b);
if (opt->optlen >= DNSOpt_OwnerData_ID_Wake_Space-4)
{
length += mDNS_snprintf(buffer+length, RemSpc, " I-MAC %.6a", opt->u.owner.IMAC.b);
if (opt->optlen > DNSOpt_OwnerData_ID_Wake_Space-4)
length += mDNS_snprintf(buffer+length, RemSpc, " Password %.6a", opt->u.owner.password.b);
}
break;
case kDNSOpt_Trace:
length += mDNS_snprintf(buffer+length, RemSpc, " Trace");
length += mDNS_snprintf(buffer+length, RemSpc, " Platform %d", opt->u.tracer.platf);
length += mDNS_snprintf(buffer+length, RemSpc, " mDNSVers %d", opt->u.tracer.mDNSv);
break;
case kDNSOpt_TSR:
length += mDNS_snprintf(buffer+length, RemSpc, " TSR");
length += mDNS_snprintf(buffer+length, RemSpc, " Tm %d", opt->u.tsr.timeStamp);
length += mDNS_snprintf(buffer+length, RemSpc, " Hk %x", opt->u.tsr.hostkeyHash);
length += mDNS_snprintf(buffer+length, RemSpc, " Ix %u", opt->u.tsr.recIndex);
break;
default:
length += mDNS_snprintf(buffer+length, RemSpc, " Unknown %d", opt->opt);
break;
}
}
}
break;
#if MDNSRESPONDER_SUPPORTS(APPLE, DNSSECv2)
case kDNSType_DS: {
// See <https://datatracker.ietf.org/doc/html/rfc4034#section-5.3> for DS RR Presentation Format.
dnssec_error_t err;
dnssec_obj_rr_ds_t ds = mDNSNULL;
char *ds_rdata_description = mDNSNULL;
ds = dnssec_obj_rr_ds_create(rr->name->c, rr->rrclass, rr->rdata->u.data, rr->rdlength, false, &err);
if (err != DNSSEC_ERROR_NO_ERROR)
{
goto ds_exit;
}
ds_rdata_description = dnssec_obj_rr_copy_rdata_rfc_description(ds, &err);
if (err != DNSSEC_ERROR_NO_ERROR)
{
goto ds_exit;
}
mDNS_snprintf(buffer + length, RemSpc, "%s", ds_rdata_description);
ds_exit:
MDNS_DISPOSE_DNSSEC_OBJ(ds);
mDNSPlatformMemFree(ds_rdata_description);
}
break;
case kDNSType_RRSIG: {
// See <https://datatracker.ietf.org/doc/html/rfc4034#section-3.2> for RRSIG RR Presentation Format.
dnssec_error_t err;
dnssec_obj_rr_rrsig_t rrsig = NULL;
char *rrsig_rdata_description = mDNSNULL;
rrsig = dnssec_obj_rr_rrsig_create(rr->name->c, rr->rdata->u.data, rr->rdlength, false, &err);
if (err != DNSSEC_ERROR_NO_ERROR) {
goto rrsig_exit;
}
rrsig_rdata_description = dnssec_obj_rr_copy_rdata_rfc_description(rrsig, &err);
if (err != DNSSEC_ERROR_NO_ERROR)
{
goto rrsig_exit;
}
mDNS_snprintf(buffer + length, RemSpc, "%s", rrsig_rdata_description);
rrsig_exit:
MDNS_DISPOSE_DNSSEC_OBJ(rrsig);
mDNSPlatformMemFree(rrsig_rdata_description);
}
break;
#endif
case kDNSType_NSEC: {
const domainname *next = (const domainname *)rd->data;
int len, bitmaplen;
const mDNSu8 *bmap;
len = DomainNameLength(next);
bitmaplen = rr->rdlength - len;
bmap = (const mDNSu8 *)((const mDNSu8 *)next + len);
if (UNICAST_NSEC(rr))
length += mDNS_snprintf(buffer+length, RemSpc, "%##s ", next->c);
PrintTypeBitmap(bmap, bitmaplen, buffer, length);
}
break;
#if MDNSRESPONDER_SUPPORTS(APPLE, DNSSECv2)
case kDNSType_DNSKEY: {
// See <https://datatracker.ietf.org/doc/html/rfc4034#section-2.2> for DNSKEY RR Presentation Format.
dnssec_error_t err;
dnssec_obj_rr_dnskey_t dnskey = mDNSNULL;
char *dnskey_rdata_description = mDNSNULL;
dnskey = dnssec_obj_rr_dnskey_create(rr->name->c, rr->rrclass, rr->rdata->u.data, rr->rdlength, false, &err);
if (err != DNSSEC_ERROR_NO_ERROR) {
goto dnskey_exit;
}
dnskey_rdata_description = dnssec_obj_rr_copy_rdata_rfc_description(dnskey, &err);
if (err != DNSSEC_ERROR_NO_ERROR) {
goto dnskey_exit;
}
mDNS_snprintf(buffer + length, RemSpc, "%s", dnskey_rdata_description);
dnskey_exit:
MDNS_DISPOSE_DNSSEC_OBJ(dnskey);
mDNSPlatformMemFree(dnskey_rdata_description);
}
break;
#endif
default: mDNS_snprintf(buffer+length, RemSpc, "RDLen %d: %.*s", rr->rdlength, rr->rdlength, rd->data);
// Really should scan buffer to check if text is valid UTF-8 and only replace with dots if not
for (ptr = buffer; *ptr; ptr++) if (*ptr < ' ') *ptr = '.';
break;
}
return(buffer);
}
#if MDNSRESPONDER_SUPPORTS(APPLE, OS_LOG)
mDNSexport const mDNSu8 *GetPrintableRDataBytes(mDNSu8 *const outBuffer, const mDNSu32 bufferLen,
const mDNSu16 recordType, const mDNSu8 * const rdata, const mDNSu32 rdataLen)
{
const mDNSu32 totalLen = rdataLen + 2;
mdns_require_return_value(bufferLen >= totalLen, mDNSNULL);
outBuffer[0] = (mDNSu8)((recordType >> 8) & 0xFF);
outBuffer[1] = (mDNSu8)((recordType ) & 0xFF);
mDNSPlatformMemCopy(&outBuffer[2], rdata, (mDNSu32)rdataLen);
return outBuffer;
}
#endif
// See comments in mDNSEmbeddedAPI.h
#if _PLATFORM_HAS_STRONG_PRNG_
#define mDNSRandomNumber mDNSPlatformRandomNumber
#else
mDNSlocal mDNSu32 mDNSRandomFromSeed(mDNSu32 seed)
{
return seed * 21 + 1;
}
mDNSlocal mDNSu32 mDNSMixRandomSeed(mDNSu32 seed, mDNSu8 iteration)
{
return iteration ? mDNSMixRandomSeed(mDNSRandomFromSeed(seed), --iteration) : seed;
}
mDNSlocal mDNSu32 mDNSRandomNumber()
{
static mDNSBool seeded = mDNSfalse;
static mDNSu32 seed = 0;
if (!seeded)
{
seed = mDNSMixRandomSeed(mDNSPlatformRandomSeed(), 100);
seeded = mDNStrue;
}
return (seed = mDNSRandomFromSeed(seed));
}
#endif // ! _PLATFORM_HAS_STRONG_PRNG_
mDNSexport mDNSu32 mDNSRandom(mDNSu32 max) // Returns pseudo-random result from zero to max inclusive
{
mDNSu32 ret = 0;
mDNSu32 mask = 1;
while (mask < max) mask = (mask << 1) | 1;
do ret = mDNSRandomNumber() & mask;
while (ret > max);
return ret;
}
// See <https://datatracker.ietf.org/doc/html/draft-eastlake-fnv-19#section-5>
#define MDNSRESPONDER_FNV_32_BIT_OFFSET_BASIS ((mDNSu32)0x811C9DC5)
#define MDNSRESPONDER_FNV_32_BIT_PRIME ((mDNSu32)0x01000193)
mDNSexport mDNSu32 mDNS_NonCryptoHashUpdateBytes(const mDNSNonCryptoHash algorithm, const mDNSu32 previousHash,
const mDNSu8 *const bytes, const mDNSu32 len)
{
mDNSu32 hash = previousHash;
switch (algorithm) {
case mDNSNonCryptoHash_FNV1a:
{
for (mDNSu32 i = 0; i < len; i++)
{
hash ^= bytes[i];
hash *= MDNSRESPONDER_FNV_32_BIT_PRIME;
}
}
break;
case mDNSNonCryptoHash_SDBM: // See <http://www.cse.yorku.ca/~oz/hash.html>
{
for (mDNSu32 i = 0; i < len; i++)
{
// hash(i) = hash(i - 1) * 65599 + byte
hash = bytes[i] + (hash << 6) + (hash << 16) - hash;
}
}
break;
MDNS_COVERED_SWITCH_DEFAULT:
break;
}
return hash;
}
mDNSexport mDNSu32 mDNS_NonCryptoHash(const mDNSNonCryptoHash algorithm, const mDNSu8 *const bytes, const mDNSu32 len)
{
switch (algorithm) {
case mDNSNonCryptoHash_FNV1a:
return mDNS_NonCryptoHashUpdateBytes(mDNSNonCryptoHash_FNV1a, MDNSRESPONDER_FNV_32_BIT_OFFSET_BASIS, bytes,
len);
case mDNSNonCryptoHash_SDBM:
return mDNS_NonCryptoHashUpdateBytes(mDNSNonCryptoHash_SDBM, 0, bytes, len);
MDNS_COVERED_SWITCH_DEFAULT:
return 0;
}
}
mDNSexport mDNSu32 mDNS_DomainNameFNV1aHash(const domainname *const name)
{
mDNSu32 hash = MDNSRESPONDER_FNV_32_BIT_OFFSET_BASIS;
const mDNSu32 len = DomainNameLength(name);
const mDNSu8 *const data = name->c;
for (mDNSu32 i = 0; i < len; ++i)
{
hash ^= mDNSASCIITolower(data[i]);
hash *= MDNSRESPONDER_FNV_32_BIT_PRIME;
}
return hash;
}
mDNSexport mDNSs32 mDNSGetTimeOfDay(struct timeval *const tv, struct timezone *const tz)
{
return gettimeofday(tv, tz);
}
mDNSexport mDNSBool mDNSSameAddress(const mDNSAddr *ip1, const mDNSAddr *ip2)
{
if (ip1->type == ip2->type)
{
switch (ip1->type)
{
case mDNSAddrType_None: return(mDNStrue); // Empty addresses have no data and are therefore always equal
case mDNSAddrType_IPv4: return (mDNSBool)(mDNSSameIPv4Address(ip1->ip.v4, ip2->ip.v4));
case mDNSAddrType_IPv6: return (mDNSBool)(mDNSSameIPv6Address(ip1->ip.v6, ip2->ip.v6));
default:
break;
}
}
return(mDNSfalse);
}
mDNSexport mDNSBool mDNSAddrIsDNSMulticast(const mDNSAddr *ip)
{
switch(ip->type)
{
case mDNSAddrType_IPv4: return (mDNSBool)(mDNSSameIPv4Address(ip->ip.v4, AllDNSLinkGroup_v4.ip.v4));
case mDNSAddrType_IPv6: return (mDNSBool)(mDNSSameIPv6Address(ip->ip.v6, AllDNSLinkGroup_v6.ip.v6));
default: return(mDNSfalse);
}
}
mDNSlocal mDNSBool mDNSByteInRange(const mDNSu8 byte, const mDNSu8 min, const mDNSu8 max)
{
return ((byte >= min) && (byte <= max));
}
mDNSlocal mDNSBool mDNSisUTF8Tail(const mDNSu8 byte)
{
// 0x80-0xBF is a common byte range for various well-formed UTF-8 byte sequences.
return mDNSByteInRange(byte, 0x80, 0xBF);
}
mDNSlocal mDNSBool mDNSBytesStartWithWellFormedUTF8OneByteSequence(const mDNSu8 *const bytes, const mDNSu32 len)
{
// From Table 3-7. Well-Formed UTF-8 Byte Sequences of <https://www.unicode.org/versions/Unicode15.0.0/ch03.pdf>:
//
// Code Points | First Byte
// ---------------+------------
// U+0000..U+007F | 00..7F
return ((len >= 1) && mDNSByteInRange(bytes[0], 0x00, 0x7F));
}
mDNSlocal mDNSBool mDNSBytesStartWithWellFormedUTF8TwoByteSequence(const mDNSu8 *const bytes, const mDNSu32 len)
{
// From Table 3-7. Well-Formed UTF-8 Byte Sequences of <https://www.unicode.org/versions/Unicode15.0.0/ch03.pdf>:
//
// Code Points | First Byte | Second Byte
// ---------------+------------+-------------
// U+0080..U+07FF | C2..DF | 80..BF
return ((len >= 2) && mDNSByteInRange(bytes[0], 0xC2, 0xDF) && mDNSisUTF8Tail(bytes[1]));
}
mDNSlocal mDNSBool mDNSBytesStartWithWellFormedUTF8ThreeByteSequence(const mDNSu8 *const bytes, const mDNSu32 len)
{
// From Table 3-7. Well-Formed UTF-8 Byte Sequences of <https://www.unicode.org/versions/Unicode15.0.0/ch03.pdf>:
//
// Code Points | First Byte | Second Byte | Third Byte
// ---------------+------------+-------------+------------
// U+0800..U+0FFF | E0 | A0..BF | 80..BF
// U+1000..U+CFFF | E1..EC | 80..BF | 80..BF
// U+D000..U+D7FF | ED | 80..9F | 80..BF
// U+E000..U+FFFF | EE..EF | 80..BF | 80..BF
if ((len >= 3) && mDNSisUTF8Tail(bytes[2]))
{
if (bytes[0] == 0xE0)
{
if (mDNSByteInRange(bytes[1], 0xA0, 0xBF))
{
return mDNStrue;
}
}
else if (mDNSByteInRange(bytes[0], 0xE1, 0xEC) || mDNSByteInRange(bytes[0], 0xEE, 0xEF))
{
if (mDNSisUTF8Tail(bytes[1]))
{
return mDNStrue;
}
}
else if (bytes[0] == 0xED)
{
if (mDNSByteInRange(bytes[1], 0x80, 0x9F))
{
return mDNStrue;
}
}
}
return mDNSfalse;
}
mDNSlocal mDNSBool mDNSBytesStartWithWellFormedUTF8FourByteSequence(const mDNSu8 *const bytes, const mDNSu32 len)
{
// From Table 3-7. Well-Formed UTF-8 Byte Sequences of <https://www.unicode.org/versions/Unicode15.0.0/ch03.pdf>:
//
// Code Points | First Byte | Second Byte | Third Byte | Fourth Byte
// -------------------+------------+-------------+------------+-------------
// U+10000..U+3FFFF | F0 | 90..BF | 80..BF | 80..BF
// U+40000..U+FFFFF | F1..F3 | 80..BF | 80..BF | 80..BF
// U+100000..U+10FFFF | F4 | 80..8F | 80..BF | 80..BF
if ((len >= 4) && mDNSisUTF8Tail(bytes[2]) && mDNSisUTF8Tail(bytes[3]))
{
if (bytes[0] == 0xF0)
{
if (mDNSByteInRange(bytes[1], 0x90, 0xBF))
{
return mDNStrue;
}
}
else if (mDNSByteInRange(bytes[0], 0xF1, 0xF3))
{
if (mDNSisUTF8Tail(bytes[1]))
{
return mDNStrue;
}
}
else if (bytes[0] == 0xF4)
{
if (mDNSByteInRange(bytes[1], 0x80, 0x8F))
{
return mDNStrue;
}
}
}
return mDNSfalse;
}
mDNSlocal mDNSu8 mDNSLengthOfFirstUTF8Character(const mDNSu8 *const bytes, const mDNSu32 len)
{
if (mDNSBytesStartWithWellFormedUTF8OneByteSequence(bytes, len))
{
return 1;
}
else if (mDNSBytesStartWithWellFormedUTF8TwoByteSequence(bytes, len))
{
return 2;
}
else if (mDNSBytesStartWithWellFormedUTF8ThreeByteSequence(bytes, len))
{
return 3;
}
else if (mDNSBytesStartWithWellFormedUTF8FourByteSequence(bytes, len))
{
return 4;
}
else
{
return 0;
}
}
mDNSlocal const mDNSu8 *mDNSLocateFirstMalformedUTF8Byte(const mDNSu8 *const bytes, const mDNSu32 byteLen)
{
for (const mDNSu8 *ptr = bytes, *const end = bytes + byteLen; ptr < end;)
{
const mDNSu32 utf8CharacterLen = mDNSLengthOfFirstUTF8Character(ptr, (mDNSu32)(end - ptr));
if (utf8CharacterLen == 0)
{
return ptr;
}
ptr += utf8CharacterLen;
}
return mDNSNULL;
}
mDNSlocal mDNSBool mDNSAreUTF8Bytes(const mDNSu8 *const bytes, const mDNSu32 len)
{
return (mDNSLocateFirstMalformedUTF8Byte(bytes, len) == mDNSNULL);
}
mDNSexport mDNSBool mDNSAreUTF8String(const char *const str)
{
return mDNSAreUTF8Bytes((const mDNSu8 *)str, mDNSPlatformStrLen(str));
}
mDNSexport mDNSu32 GetEffectiveTTL(const uDNS_LLQType LLQType, mDNSu32 ttl) // TTL in seconds
{
if (LLQType == uDNS_LLQ_Entire) ttl = kLLQ_DefLease;
else if (LLQType == uDNS_LLQ_Events)
{
// If the TTL is -1 for uDNS LLQ event packet, that means "remove"
if (ttl == 0xFFFFFFFF) ttl = 0;
else ttl = kLLQ_DefLease;
}
else // else not LLQ (standard uDNS response)
{
// The TTL is already capped to a maximum value in GetLargeResourceRecord, but just to be extra safe we
// also do this check here to make sure we can't get overflow below when we add a quarter to the TTL
if (ttl > 0x60000000UL / mDNSPlatformOneSecond) ttl = 0x60000000UL / mDNSPlatformOneSecond;
ttl = RRAdjustTTL(ttl);
// For mDNS, TTL zero means "delete this record"
// For uDNS, TTL zero means: this data is true at this moment, but don't cache it.
// For the sake of network efficiency, we impose a minimum effective TTL of 15 seconds.
// This means that we'll do our 80, 85, 90, 95% queries at 12.00, 12.75, 13.50, 14.25 seconds
// respectively, and then if we get no response, delete the record from the cache at 15 seconds.
// This gives the server up to three seconds to respond between when we send our 80% query at 12 seconds
// and when we delete the record at 15 seconds. Allowing cache lifetimes less than 15 seconds would
// (with the current code) result in the server having even less than three seconds to respond
// before we deleted the record and reported a "remove" event to any active questions.
// Furthermore, with the current code, if we were to allow a TTL of less than 2 seconds
// then things really break (e.g. we end up making a negative cache entry).
// In the future we may want to revisit this and consider properly supporting non-cached (TTL=0) uDNS answers.
if (ttl < 15) ttl = 15;
}
return ttl;
}
// ***************************************************************************
// MARK: - Domain Name Utility Functions
mDNSexport mDNSBool SameDomainLabel(const mDNSu8 *a, const mDNSu8 *b)
{
int i;
const int len = *a++;
if (len > MAX_DOMAIN_LABEL)
{ debugf("Malformed label (too long)"); return(mDNSfalse); }
if (len != *b++) return(mDNSfalse);
for (i=0; i<len; i++)
{
mDNSu8 ac = *a++;
mDNSu8 bc = *b++;
if (mDNSIsUpperCase(ac)) ac += 'a' - 'A';
if (mDNSIsUpperCase(bc)) bc += 'a' - 'A';
if (ac != bc) return(mDNSfalse);
}
return(mDNStrue);
}
mDNSexport mDNSBool SameDomainName(const domainname *const d1, const domainname *const d2)
{
return(SameDomainNameBytes(d1->c, d2->c));
}
mDNSexport mDNSBool SameDomainNameBytes(const mDNSu8 *const d1, const mDNSu8 *const d2)
{
const mDNSu8 * a = d1;
const mDNSu8 * b = d2;
const mDNSu8 *const max = d1 + MAX_DOMAIN_NAME; // Maximum that's valid
while (*a || *b)
{
if (a + 1 + *a >= max)
{ debugf("Malformed domain name (more than 256 characters)"); return(mDNSfalse); }
if (!SameDomainLabel(a, b)) return(mDNSfalse);
a += 1 + *a;
b += 1 + *b;
}
return(mDNStrue);
}
mDNSexport mDNSBool SameDomainNameCS(const domainname *const d1, const domainname *const d2)
{
mDNSu16 l1 = DomainNameLength(d1);
mDNSu16 l2 = DomainNameLength(d2);
return(l1 <= MAX_DOMAIN_NAME && l1 == l2 && mDNSPlatformMemSame(d1, d2, l1));
}
mDNSexport mDNSBool IsSubdomain(const domainname *const subdomain, const domainname *const domain)
{
mDNSBool isSubdomain = mDNSfalse;
const int subdomainLabelCount = CountLabels(subdomain);
const int domainLabelCount = CountLabels(domain);
if (subdomainLabelCount >= domainLabelCount)
{
const domainname *const parentDomain = SkipLeadingLabels(subdomain, subdomainLabelCount - domainLabelCount);
isSubdomain = SameDomainName(parentDomain, domain);
}
return isSubdomain;
}
mDNSexport mDNSBool IsLocalDomain(const domainname *d)
{
// Domains that are defined to be resolved via link-local multicast are:
// local., 254.169.in-addr.arpa., and {8,9,A,B}.E.F.ip6.arpa.
static const domainname *nL = (const domainname*)"\x5" "local";
static const domainname *nR = (const domainname*)"\x3" "254" "\x3" "169" "\x7" "in-addr" "\x4" "arpa";
static const domainname *n8 = (const domainname*)"\x1" "8" "\x1" "e" "\x1" "f" "\x3" "ip6" "\x4" "arpa";
static const domainname *n9 = (const domainname*)"\x1" "9" "\x1" "e" "\x1" "f" "\x3" "ip6" "\x4" "arpa";
static const domainname *nA = (const domainname*)"\x1" "a" "\x1" "e" "\x1" "f" "\x3" "ip6" "\x4" "arpa";
static const domainname *nB = (const domainname*)"\x1" "b" "\x1" "e" "\x1" "f" "\x3" "ip6" "\x4" "arpa";
const domainname *d1, *d2, *d3, *d4, *d5; // Top-level domain, second-level domain, etc.
d1 = d2 = d3 = d4 = d5 = mDNSNULL;
while (d->c[0])
{
d5 = d4; d4 = d3; d3 = d2; d2 = d1; d1 = d;
d = (const domainname*)(d->c + 1 + d->c[0]);
}
if (d1 && SameDomainName(d1, nL)) return(mDNStrue);
if (d4 && SameDomainName(d4, nR)) return(mDNStrue);
if (d5 && SameDomainName(d5, n8)) return(mDNStrue);
if (d5 && SameDomainName(d5, n9)) return(mDNStrue);
if (d5 && SameDomainName(d5, nA)) return(mDNStrue);
if (d5 && SameDomainName(d5, nB)) return(mDNStrue);
return(mDNSfalse);
}
mDNSexport mDNSBool IsRootDomain(const domainname *const d)
{
return (d->c[0] == 0);
}
mDNSexport const mDNSu8 *LastLabel(const domainname *d)
{
const mDNSu8 *p = d->c;
while (d->c[0])
{
p = d->c;
d = (const domainname*)(d->c + 1 + d->c[0]);
}
return(p);
}
// Returns length of a domain name INCLUDING the byte for the final null label
// e.g. for the root label "." it returns one
// For the FQDN "com." it returns 5 (length byte, three data bytes, final zero)
// Legal results are 1 (just root label) to 256 (MAX_DOMAIN_NAME)
// If the given domainname is invalid, result is 257 (MAX_DOMAIN_NAME+1)
mDNSexport mDNSu16 DomainNameLengthLimit(const domainname *const name, const mDNSu8 *const limit)
{
return(DomainNameBytesLength(name->c, limit));
}
mDNSexport mDNSu16 DomainNameBytesLength(const mDNSu8 *const name, const mDNSu8 *const limit)
{
const mDNSu8 *src = name;
while ((!limit || (src < limit)) && src && (*src <= MAX_DOMAIN_LABEL))
{
if (*src == 0) return((mDNSu16)(src - name + 1));
src += 1 + *src;
}
return(MAX_DOMAIN_NAME+1);
}
mDNSexport mDNSu8 DomainLabelLength(const domainlabel *const label)
{
return label->c[0];
}
// CompressedDomainNameLength returns the length of a domain name INCLUDING the byte
// for the final null label, e.g. for the root label "." it returns one.
// E.g. for the FQDN "foo.com." it returns 9
// (length, three data bytes, length, three more data bytes, final zero).
// In the case where a parent domain name is provided, and the given name is a child
// of that parent, CompressedDomainNameLength returns the length of the prefix portion
// of the child name, plus TWO bytes for the compression pointer.
// E.g. for the name "foo.com." with parent "com.", it returns 6
// (length, three data bytes, two-byte compression pointer).
mDNSexport mDNSu16 CompressedDomainNameLength(const domainname *const name, const domainname *parent)
{
const mDNSu8 *src = name->c;
if (parent && parent->c[0] == 0) parent = mDNSNULL;
while (*src)
{
if (*src > MAX_DOMAIN_LABEL) return(MAX_DOMAIN_NAME+1);
if (parent && SameDomainName((const domainname *)src, parent)) return((mDNSu16)(src - name->c + 2));
src += 1 + *src;
if (src - name->c >= MAX_DOMAIN_NAME) return(MAX_DOMAIN_NAME+1);
}
return((mDNSu16)(src - name->c + 1));
}
// CountLabels() returns number of labels in name, excluding final root label
// (e.g. for "apple.com." CountLabels returns 2.)
mDNSexport int CountLabels(const domainname *d)
{
int count = 0;
const mDNSu8 *ptr;
for (ptr = d->c; *ptr; ptr = ptr + ptr[0] + 1) count++;
return count;
}
// SkipLeadingLabels skips over the first 'skip' labels in the domainname,
// returning a pointer to the suffix with 'skip' labels removed.
mDNSexport const domainname *SkipLeadingLabels(const domainname *d, int skip)
{
while (skip > 0 && d->c[0]) { d = (const domainname *)(d->c + 1 + d->c[0]); skip--; }
return(d);
}
// AppendLiteralLabelString appends a single label to an existing (possibly empty) domainname.
// The C string contains the label as-is, with no escaping, etc.
// Any dots in the name are literal dots, not label separators
// If successful, AppendLiteralLabelString returns a pointer to the next unused byte
// in the domainname bufer (i.e. the next byte after the terminating zero).
// If unable to construct a legal domain name (i.e. label more than 63 bytes, or total more than 256 bytes)
// AppendLiteralLabelString returns mDNSNULL.
mDNSexport mDNSu8 *AppendLiteralLabelString(domainname *const name, const char *cstr)
{
mDNSu8 * ptr = name->c + DomainNameLength(name) - 1; // Find end of current name
const mDNSu8 *const lim1 = name->c + MAX_DOMAIN_NAME - 1; // Limit of how much we can add (not counting final zero)
const mDNSu8 *const lim2 = ptr + 1 + MAX_DOMAIN_LABEL;
const mDNSu8 *const lim = (lim1 < lim2) ? lim1 : lim2;
mDNSu8 *lengthbyte = ptr++; // Record where the length is going to go
while (*cstr && ptr < lim) *ptr++ = (mDNSu8)*cstr++; // Copy the data
*lengthbyte = (mDNSu8)(ptr - lengthbyte - 1); // Fill in the length byte
*ptr++ = 0; // Put the null root label on the end
if (*cstr) return(mDNSNULL); // Failure: We didn't successfully consume all input
else return(ptr); // Success: return new value of ptr
}
// AppendDNSNameString appends zero or more labels to an existing (possibly empty) domainname.
// The C string is in conventional DNS syntax:
// Textual labels, escaped as necessary using the usual DNS '\' notation, separated by dots.
// If successful, AppendDNSNameString returns a pointer to the next unused byte
// in the domainname bufer (i.e. the next byte after the terminating zero).
// If unable to construct a legal domain name (i.e. label more than 63 bytes, or total more than 256 bytes)
// AppendDNSNameString returns mDNSNULL.
mDNSexport mDNSu8 *AppendDNSNameString(domainname *const name, const char *cstring)
{
const char * cstr = cstring;
mDNSu8 * ptr = name->c + DomainNameLength(name) - 1; // Find end of current name
const mDNSu8 *const lim = name->c + MAX_DOMAIN_NAME - 1; // Limit of how much we can add (not counting final zero)
if (cstr[0] == '.' && cstr[1] == '\0') cstr++; // If the domain to be appended is root domain, skip it.
while (*cstr && ptr < lim) // While more characters, and space to put them...
{
mDNSu8 *lengthbyte = ptr++; // Record where the length is going to go
if (*cstr == '.') { LogMsg("AppendDNSNameString: Illegal empty label in name \"%s\"", cstring); return(mDNSNULL); }
while (*cstr && *cstr != '.' && ptr < lim) // While we have characters in the label...
{
mDNSu8 c = (mDNSu8)*cstr++; // Read the character
if (c == '\\') // If escape character, check next character
{
if (*cstr == '\0') break; // If this is the end of the string, then break
c = (mDNSu8)*cstr++; // Assume we'll just take the next character
if (mDNSIsDigit(cstr[-1]) && mDNSIsDigit(cstr[0]) && mDNSIsDigit(cstr[1]))
{ // If three decimal digits,
int v0 = cstr[-1] - '0'; // then interpret as three-digit decimal
int v1 = cstr[ 0] - '0';
int v2 = cstr[ 1] - '0';
int val = v0 * 100 + v1 * 10 + v2;
if (val <= 255) { c = (mDNSu8)val; cstr += 2; } // If valid three-digit decimal value, use it
}
}
*ptr++ = c; // Write the character
}
if (*cstr == '.') cstr++; // Skip over the trailing dot (if present)
if (ptr - lengthbyte - 1 > MAX_DOMAIN_LABEL) // If illegal label, abort
return(mDNSNULL);
*lengthbyte = (mDNSu8)(ptr - lengthbyte - 1); // Fill in the length byte
}
*ptr++ = 0; // Put the null root label on the end
if (*cstr) return(mDNSNULL); // Failure: We didn't successfully consume all input
else return(ptr); // Success: return new value of ptr
}
// AppendDomainLabel appends a single label to a name.
// If successful, AppendDomainLabel returns a pointer to the next unused byte
// in the domainname bufer (i.e. the next byte after the terminating zero).
// If unable to construct a legal domain name (i.e. label more than 63 bytes, or total more than 256 bytes)
// AppendDomainLabel returns mDNSNULL.
mDNSexport mDNSu8 *AppendDomainLabel(domainname *const name, const domainlabel *const label)
{
int i;
mDNSu8 *ptr = name->c + DomainNameLength(name) - 1;
// Check label is legal
if (label->c[0] > MAX_DOMAIN_LABEL) return(mDNSNULL);
// Check that ptr + length byte + data bytes + final zero does not exceed our limit
if (ptr + 1 + label->c[0] + 1 > name->c + MAX_DOMAIN_NAME) return(mDNSNULL);
for (i=0; i<=label->c[0]; i++) *ptr++ = label->c[i]; // Copy the label data
*ptr++ = 0; // Put the null root label on the end
return(ptr);
}
mDNSexport mDNSu8 *AppendDomainName(domainname *const name, const domainname *const append)
{
mDNSu8 * ptr = name->c + DomainNameLength(name) - 1; // Find end of current name
const mDNSu8 *const lim = name->c + MAX_DOMAIN_NAME - 1; // Limit of how much we can add (not counting final zero)
const mDNSu8 * src = append->c;
while (src[0])
{
int i;
if (ptr + 1 + src[0] > lim) return(mDNSNULL);
for (i=0; i<=src[0]; i++) *ptr++ = src[i];
*ptr = 0; // Put the null root label on the end
src += i;
}
return(ptr);
}
// MakeDomainLabelFromLiteralString makes a single domain label from a single literal C string (with no escaping).
// If successful, MakeDomainLabelFromLiteralString returns mDNStrue.
// If unable to convert the whole string to a legal domain label (i.e. because length is more than 63 bytes) then
// MakeDomainLabelFromLiteralString makes a legal domain label from the first 63 bytes of the string and returns mDNSfalse.
// In some cases silently truncated oversized names to 63 bytes is acceptable, so the return result may be ignored.
// In other cases silent truncation may not be acceptable, so in those cases the calling function needs to check the return result.
mDNSexport mDNSBool MakeDomainLabelFromLiteralString(domainlabel *const label, const char *cstr)
{
mDNSu8 * ptr = label->c + 1; // Where we're putting it
const mDNSu8 *const limit = label->c + 1 + MAX_DOMAIN_LABEL; // The maximum we can put
while (*cstr && ptr < limit) *ptr++ = (mDNSu8)*cstr++; // Copy the label
label->c[0] = (mDNSu8)(ptr - label->c - 1); // Set the length byte
return(*cstr == 0); // Return mDNStrue if we successfully consumed all input
}
// MakeDomainNameFromDNSNameString makes a native DNS-format domainname from a C string.
// The C string is in conventional DNS syntax:
// Textual labels, escaped as necessary using the usual DNS '\' notation, separated by dots.
// If successful, MakeDomainNameFromDNSNameString returns a pointer to the next unused byte
// in the domainname bufer (i.e. the next byte after the terminating zero).
// If unable to construct a legal domain name (i.e. label more than 63 bytes, or total more than 256 bytes)
// MakeDomainNameFromDNSNameString returns mDNSNULL.
mDNSexport mDNSu8 *MakeDomainNameFromDNSNameString(domainname *const name, const char *cstr)
{
name->c[0] = 0; // Make an empty domain name
return(AppendDNSNameString(name, cstr)); // And then add this string to it
}
mDNSexport char *ConvertDomainLabelToCString_withescape(const domainlabel *const label, char *ptr, char esc)
{
const mDNSu8 * src = label->c; // Domain label we're reading
const mDNSu8 len = *src++; // Read length of this (non-null) label
const mDNSu8 *const end = src + len; // Work out where the label ends
if (len > MAX_DOMAIN_LABEL) return(mDNSNULL); // If illegal label, abort
while (src < end) // While we have characters in the label
{
mDNSu8 c = *src++;
if (esc)
{
if (c == '.' || c == esc) // If character is a dot or the escape character
*ptr++ = esc; // Output escape character
else if (c <= ' ') // If non-printing ascii,
{ // Output decimal escape sequence
*ptr++ = esc;
*ptr++ = (char) ('0' + (c / 100) );
*ptr++ = (char) ('0' + (c / 10) % 10);
c = (mDNSu8)('0' + (c ) % 10);
}
}
*ptr++ = (char)c; // Copy the character
}
*ptr = 0; // Null-terminate the string
return(ptr); // and return
}
// Note: To guarantee that there will be no possible overrun, cstr must be at least MAX_ESCAPED_DOMAIN_NAME (1009 bytes)
mDNSexport char *ConvertDomainNameToCString_withescape(const domainname *const name, char *ptr, char esc)
{
const mDNSu8 *src = name->c; // Domain name we're reading
const mDNSu8 *const max = name->c + MAX_DOMAIN_NAME; // Maximum that's valid
if (*src == 0) *ptr++ = '.'; // Special case: For root, just write a dot
while (*src) // While more characters in the domain name
{
if (src + 1 + *src >= max) return(mDNSNULL);
ptr = ConvertDomainLabelToCString_withescape((const domainlabel *)src, ptr, esc);
if (!ptr) return(mDNSNULL);
src += 1 + *src;
*ptr++ = '.'; // Write the dot after the label
}
*ptr++ = 0; // Null-terminate the string
return(ptr); // and return
}
// RFC 1034 rules:
// Host names must start with a letter, end with a letter or digit,
// and have as interior characters only letters, digits, and hyphen.
// This was subsequently modified in RFC 1123 to allow the first character to be either a letter or a digit
mDNSexport void ConvertUTF8PstringToRFC1034HostLabel(const mDNSu8 UTF8Name[], domainlabel *const hostlabel)
{
const mDNSu8 * src = &UTF8Name[1];
const mDNSu8 *const end = &UTF8Name[1] + UTF8Name[0];
mDNSu8 * ptr = &hostlabel->c[1];
const mDNSu8 *const lim = &hostlabel->c[1] + MAX_DOMAIN_LABEL;
while (src < end)
{
// Delete apostrophes from source name
if (src[0] == '\'') { src++; continue; } // Standard straight single quote
if (src + 2 < end && src[0] == 0xE2 && src[1] == 0x80 && src[2] == 0x99)
{ src += 3; continue; } // Unicode curly apostrophe
if (ptr < lim)
{
if (mDNSValidHostChar(*src, (ptr > &hostlabel->c[1]), (src < end-1))) *ptr++ = *src;
else if (ptr > &hostlabel->c[1] && ptr[-1] != '-') *ptr++ = '-';
}
src++;
}
while (ptr > &hostlabel->c[1] && ptr[-1] == '-') ptr--; // Truncate trailing '-' marks
hostlabel->c[0] = (mDNSu8)(ptr - &hostlabel->c[1]);
}
mDNSexport mDNSu8 *ConstructServiceName(domainname *const fqdn,
const domainlabel *name, const domainname *type, const domainname *const domain)
{
int i, len;
mDNSu8 *dst = fqdn->c;
const mDNSu8 *src;
const char *errormsg;
// In the case where there is no name (and ONLY in that case),
// a single-label subtype is allowed as the first label of a three-part "type"
if (!name)
{
const mDNSu8 *s0 = type->c;
if (s0[0] && s0[0] < 0x40) // If legal first label (at least one character, and no more than 63)
{
const mDNSu8 * s1 = s0 + 1 + s0[0];
if (s1[0] && s1[0] < 0x40) // and legal second label (at least one character, and no more than 63)
{
const mDNSu8 *s2 = s1 + 1 + s1[0];
if (s2[0] && s2[0] < 0x40 && s2[1+s2[0]] == 0) // and we have three and only three labels
{
static const mDNSu8 SubTypeLabel[5] = mDNSSubTypeLabel;
src = s0; // Copy the first label
len = *src;
for (i=0; i <= len; i++) *dst++ = *src++;
for (i=0; i < (int)sizeof(SubTypeLabel); i++) *dst++ = SubTypeLabel[i];
type = (const domainname *)s1;
// Special support to enable the DNSServiceBrowse call made by Bonjour Browser
// For these queries, we retract the "._sub" we just added between the subtype and the main type
// Remove after Bonjour Browser is updated to use DNSServiceQueryRecord instead of DNSServiceBrowse
if (SameDomainName((const domainname*)s0, (const domainname*)"\x09_services\x07_dns-sd\x04_udp"))
dst -= sizeof(SubTypeLabel);
}
}
}
}
if (name && name->c[0])
{
src = name->c; // Put the service name into the domain name
len = *src;
if (len >= 0x40) { errormsg = "Service instance name too long"; goto fail; }
for (i=0; i<=len; i++) *dst++ = *src++;
}
else
name = (domainlabel*)""; // Set this up to be non-null, to avoid errors if we have to call LogMsg() below
src = type->c; // Put the service type into the domain name
len = *src;
if (len < 2 || len > 16)
{
LogRedact(MDNS_LOG_CATEGORY_DEFAULT, MDNS_LOG_DEFAULT, "Bad service type in " PRI_DM_LABEL "." PRI_DM_NAME PRI_DM_NAME" Application protocol name must be "
"underscore plus 1-15 characters. See <http://www.dns-sd.org/ServiceTypes.html>",
DM_LABEL_PARAM(name), DM_NAME_PARAM(type), DM_NAME_PARAM(domain));
}
if (len < 2 || len >= 0x40 || (len > 16 && !SameDomainName(domain, &localdomain))) return(mDNSNULL);
if (src[1] != '_') { errormsg = "Application protocol name must begin with underscore"; goto fail; }
for (i=2; i<=len; i++)
{
// Letters and digits are allowed anywhere
if (mDNSIsLetter(src[i]) || mDNSIsDigit(src[i])) continue;
// Hyphens are only allowed as interior characters
// Underscores are not supposed to be allowed at all, but for backwards compatibility with some old products we do allow them,
// with the same rule as hyphens
if ((src[i] == '-' || src[i] == '_') && i > 2 && i < len)
{
continue;
}
errormsg = "Application protocol name must contain only letters, digits, and hyphens";
goto fail;
}
for (i=0; i<=len; i++) *dst++ = *src++;
len = *src;
if (!ValidTransportProtocol(src)) { errormsg = "Transport protocol name must be _udp or _tcp"; goto fail; }
for (i=0; i<=len; i++) *dst++ = *src++;
if (*src) { errormsg = "Service type must have only two labels"; goto fail; }
*dst = 0;
if (!domain->c[0]) { errormsg = "Service domain must be non-empty"; goto fail; }
if (SameDomainName(domain, (const domainname*)"\x05" "local" "\x04" "arpa"))
{ errormsg = "Illegal domain \"local.arpa.\" Use \"local.\" (or empty string)"; goto fail; }
dst = AppendDomainName(fqdn, domain);
if (!dst) { errormsg = "Service domain too long"; goto fail; }
return(dst);
fail:
LogRedact(MDNS_LOG_CATEGORY_DEFAULT, MDNS_LOG_DEFAULT, "ConstructServiceName: " PUB_S ": " PRI_DM_LABEL "." PRI_DM_NAME PRI_DM_NAME , errormsg,
DM_LABEL_PARAM(name), DM_NAME_PARAM(type), DM_NAME_PARAM(domain));
return(mDNSNULL);
}
// A service name has the form: instance.application-protocol.transport-protocol.domain
// DeconstructServiceName is currently fairly forgiving: It doesn't try to enforce character
// set or length limits for the protocol names, and the final domain is allowed to be empty.
// However, if the given FQDN doesn't contain at least three labels,
// DeconstructServiceName will reject it and return mDNSfalse.
mDNSexport mDNSBool DeconstructServiceName(const domainname *const fqdn,
domainlabel *const name, domainname *const type, domainname *const domain)
{
int i, len;
const mDNSu8 *src = fqdn->c;
const mDNSu8 *max = fqdn->c + MAX_DOMAIN_NAME;
mDNSu8 *dst;
dst = name->c; // Extract the service name
len = *src;
if (!len) { debugf("DeconstructServiceName: FQDN empty!"); return(mDNSfalse); }
if (len >= 0x40) { debugf("DeconstructServiceName: Instance name too long"); return(mDNSfalse); }
for (i=0; i<=len; i++) *dst++ = *src++;
dst = type->c; // Extract the service type
len = *src;
if (!len) { debugf("DeconstructServiceName: FQDN contains only one label!"); return(mDNSfalse); }
if (len >= 0x40) { debugf("DeconstructServiceName: Application protocol name too long"); return(mDNSfalse); }
if (src[1] != '_') { debugf("DeconstructServiceName: No _ at start of application protocol"); return(mDNSfalse); }
for (i=0; i<=len; i++) *dst++ = *src++;
len = *src;
if (!len) { debugf("DeconstructServiceName: FQDN contains only two labels!"); return(mDNSfalse); }
if (!ValidTransportProtocol(src))
{ debugf("DeconstructServiceName: Transport protocol must be _udp or _tcp"); return(mDNSfalse); }
for (i=0; i<=len; i++) *dst++ = *src++;
*dst++ = 0; // Put terminator on the end of service type
dst = domain->c; // Extract the service domain
while (*src)
{
len = *src;
if (len >= 0x40)
{ debugf("DeconstructServiceName: Label in service domain too long"); return(mDNSfalse); }
if (src + 1 + len + 1 >= max)
{ debugf("DeconstructServiceName: Total service domain too long"); return(mDNSfalse); }
for (i=0; i<=len; i++) *dst++ = *src++;
}
*dst++ = 0; // Put the null root label on the end
return(mDNStrue);
}
mDNSexport mStatus DNSNameToLowerCase(domainname *d, domainname *result)
{
const mDNSu8 *a = d->c;
mDNSu8 *b = result->c;
const mDNSu8 *const max = d->c + MAX_DOMAIN_NAME;
int i, len;
while (*a)
{
if (a + 1 + *a >= max)
{
LogMsg("DNSNameToLowerCase: ERROR!! Malformed Domain name");
return mStatus_BadParamErr;
}
len = *a++;
*b++ = len;
for (i = 0; i < len; i++)
{
mDNSu8 ac = *a++;
if (mDNSIsUpperCase(ac)) ac += 'a' - 'A';
*b++ = ac;
}
}
*b = 0;
return mStatus_NoError;
}
// Notes on UTF-8:
// 0xxxxxxx represents a 7-bit ASCII value from 0x00 to 0x7F
// 10xxxxxx is a continuation byte of a multi-byte character
// 110xxxxx is the first byte of a 2-byte character (11 effective bits; values 0x 80 - 0x 800-1)
// 1110xxxx is the first byte of a 3-byte character (16 effective bits; values 0x 800 - 0x 10000-1)
// 11110xxx is the first byte of a 4-byte character (21 effective bits; values 0x 10000 - 0x 200000-1)
// 111110xx is the first byte of a 5-byte character (26 effective bits; values 0x 200000 - 0x 4000000-1)
// 1111110x is the first byte of a 6-byte character (31 effective bits; values 0x4000000 - 0x80000000-1)
//
// UTF-16 surrogate pairs are used in UTF-16 to encode values larger than 0xFFFF.
// Although UTF-16 surrogate pairs are not supposed to appear in legal UTF-8, we want to be defensive
// about that too. (See <http://www.unicode.org/faq/utf_bom.html#34>, "What are surrogates?")
// The first of pair is a UTF-16 value in the range 0xD800-0xDBFF (11101101 1010xxxx 10xxxxxx in UTF-8),
// and the second is a UTF-16 value in the range 0xDC00-0xDFFF (11101101 1011xxxx 10xxxxxx in UTF-8).
mDNSexport mDNSu32 TruncateUTF8ToLength(mDNSu8 *string, mDNSu32 length, mDNSu32 max)
{
if (length > max)
{
mDNSu8 c1 = string[max]; // First byte after cut point
mDNSu8 c2 = (max+1 < length) ? string[max+1] : (mDNSu8)0xB0; // Second byte after cut point
length = max; // Trim length down
while (length > 0)
{
// Check if the byte right after the chop point is a UTF-8 continuation byte,
// or if the character right after the chop point is the second of a UTF-16 surrogate pair.
// If so, then we continue to chop more bytes until we get to a legal chop point.
mDNSBool continuation = ((c1 & 0xC0) == 0x80);
mDNSBool secondsurrogate = (c1 == 0xED && (c2 & 0xF0) == 0xB0);
if (!continuation && !secondsurrogate) break;
c2 = c1;
c1 = string[--length];
}
// Having truncated characters off the end of our string, also cut off any residual white space
while (length > 0 && string[length-1] <= ' ') length--;
}
return(length);
}
// Returns true if a rich text label ends in " (nnn)", or if an RFC 1034
// name ends in "-nnn", where n is some decimal number.
mDNSexport mDNSBool LabelContainsSuffix(const domainlabel *const name, const mDNSBool RichText)
{
mDNSu16 l = name->c[0];
if (RichText)
{
if (l < 4) return mDNSfalse; // Need at least " (2)"
if (name->c[l--] != ')') return mDNSfalse; // Last char must be ')'
if (!mDNSIsDigit(name->c[l])) return mDNSfalse; // Preceeded by a digit
l--;
while (l > 2 && mDNSIsDigit(name->c[l])) l--; // Strip off digits
return (name->c[l] == '(' && name->c[l - 1] == ' ');
}
else
{
if (l < 2) return mDNSfalse; // Need at least "-2"
if (!mDNSIsDigit(name->c[l])) return mDNSfalse; // Last char must be a digit
l--;
while (l > 2 && mDNSIsDigit(name->c[l])) l--; // Strip off digits
return (name->c[l] == '-');
}
}
// removes an auto-generated suffix (appended on a name collision) from a label. caller is
// responsible for ensuring that the label does indeed contain a suffix. returns the number
// from the suffix that was removed.
mDNSexport mDNSu32 RemoveLabelSuffix(domainlabel *name, mDNSBool RichText)
{
mDNSu32 val = 0, multiplier = 1;
// Chop closing parentheses from RichText suffix
if (RichText && name->c[0] >= 1 && name->c[name->c[0]] == ')') name->c[0]--;
// Get any existing numerical suffix off the name
while (mDNSIsDigit(name->c[name->c[0]]))
{ val += (name->c[name->c[0]] - '0') * multiplier; multiplier *= 10; name->c[0]--; }
// Chop opening parentheses or dash from suffix
if (RichText)
{
if (name->c[0] >= 2 && name->c[name->c[0]] == '(' && name->c[name->c[0]-1] == ' ') name->c[0] -= 2;
}
else
{
if (name->c[0] >= 1 && name->c[name->c[0]] == '-') name->c[0] -= 1;
}
return(val);
}
// appends a numerical suffix to a label, with the number following a whitespace and enclosed
// in parentheses (rich text) or following two consecutive hyphens (RFC 1034 domain label).
mDNSexport void AppendLabelSuffix(domainlabel *const name, mDNSu32 val, const mDNSBool RichText)
{
mDNSu32 divisor = 1, chars = 2; // Shortest possible RFC1034 name suffix is 2 characters ("-2")
if (RichText) chars = 4; // Shortest possible RichText suffix is 4 characters (" (2)")
// Truncate trailing spaces from RichText names
if (RichText) while (name->c[name->c[0]] == ' ') name->c[0]--;
while (divisor < 0xFFFFFFFFUL/10 && val >= divisor * 10) { divisor *= 10; chars++; }
name->c[0] = (mDNSu8) TruncateUTF8ToLength(name->c+1, name->c[0], MAX_DOMAIN_LABEL - chars);
if (RichText) { name->c[++name->c[0]] = ' '; name->c[++name->c[0]] = '('; }
else { name->c[++name->c[0]] = '-'; }
while (divisor)
{
name->c[++name->c[0]] = (mDNSu8)('0' + val / divisor);
val %= divisor;
divisor /= 10;
}
if (RichText) name->c[++name->c[0]] = ')';
}
mDNSexport void IncrementLabelSuffix(domainlabel *name, mDNSBool RichText)
{
mDNSu32 val = 0;
if (LabelContainsSuffix(name, RichText))
val = RemoveLabelSuffix(name, RichText);
// If no existing suffix, start by renaming "Foo" as "Foo (2)" or "Foo-2" as appropriate.
// If existing suffix in the range 2-9, increment it.
// If we've had ten conflicts already, there are probably too many hosts trying to use the same name,
// so add a random increment to improve the chances of finding an available name next time.
if (val == 0) val = 2;
else if (val < 10) val++;
else val += 1 + mDNSRandom(99);
AppendLabelSuffix(name, val, RichText);
}
// ***************************************************************************
// MARK: - Resource Record Utility Functions
// Set up a AuthRecord with sensible default values.
// These defaults may be overwritten with new values before mDNS_Register is called
mDNSexport void mDNS_SetupResourceRecord(AuthRecord *rr, RData *RDataStorage, mDNSInterfaceID InterfaceID,
mDNSu16 rrtype, mDNSu32 ttl, mDNSu8 RecordType, AuthRecType artype, mDNSRecordCallback Callback, void *Context)
{
//
// LocalOnly auth record can be created with LocalOnly InterfaceID or a valid InterfaceID.
// Most of the applications normally create with LocalOnly InterfaceID and we store them as
// such, so that we can deliver the response to questions that specify LocalOnly InterfaceID.
// LocalOnly resource records can also be created with valid InterfaceID which happens today
// when we create LocalOnly records for /etc/hosts.
if (InterfaceID == mDNSInterface_LocalOnly && artype != AuthRecordLocalOnly)
{
LogRedact(MDNS_LOG_CATEGORY_DEFAULT, MDNS_LOG_DEFAULT, "mDNS_SetupResourceRecord: ERROR!! Mismatch LocalOnly record InterfaceID %p called with artype %d",
InterfaceID, artype);
}
else if (InterfaceID == mDNSInterface_P2P && artype != AuthRecordP2P)
{
LogRedact(MDNS_LOG_CATEGORY_DEFAULT, MDNS_LOG_DEFAULT, "mDNS_SetupResourceRecord: ERROR!! Mismatch P2P record InterfaceID %p called with artype %d",
InterfaceID, artype);
}
else if (!InterfaceID && (artype == AuthRecordP2P || artype == AuthRecordLocalOnly))
{
LogRedact(MDNS_LOG_CATEGORY_DEFAULT, MDNS_LOG_DEFAULT, "mDNS_SetupResourceRecord: ERROR!! Mismatch InterfaceAny record InterfaceID %p called with artype %d",
InterfaceID, artype);
}
// Don't try to store a TTL bigger than we can represent in platform time units
if (ttl > 0x7FFFFFFFUL / mDNSPlatformOneSecond)
ttl = 0x7FFFFFFFUL / mDNSPlatformOneSecond;
else if (ttl == 0) // And Zero TTL is illegal
ttl = DefaultTTLforRRType(rrtype);
// Field Group 1: The actual information pertaining to this resource record
rr->resrec.RecordType = RecordType;
rr->resrec.InterfaceID = InterfaceID;
rr->resrec.name = &rr->namestorage;
rr->resrec.rrtype = rrtype;
rr->resrec.rrclass = kDNSClass_IN;
rr->resrec.rroriginalttl = ttl;
#if MDNSRESPONDER_SUPPORTS(APPLE, QUERIER)
rr->resrec.metadata = NULL;
#else
rr->resrec.rDNSServer = mDNSNULL;
#endif
// rr->resrec.rdlength = MUST set by client and/or in mDNS_Register_internal
// rr->resrec.rdestimate = set in mDNS_Register_internal
// rr->resrec.rdata = MUST be set by client
if (RDataStorage)
rr->resrec.rdata = RDataStorage;
else
{
rr->resrec.rdata = &rr->rdatastorage;
rr->resrec.rdata->MaxRDLength = sizeof(RDataBody);
}
// Field Group 2: Persistent metadata for Authoritative Records
rr->Additional1 = mDNSNULL;
rr->Additional2 = mDNSNULL;
rr->DependentOn = mDNSNULL;
rr->RRSet = 0;
rr->RecordCallback = Callback;
rr->RecordContext = Context;
rr->AutoTarget = Target_Manual;
rr->AllowRemoteQuery = mDNSfalse;
rr->ForceMCast = mDNSfalse;
rr->WakeUp = zeroOwner;
rr->AddressProxy = zeroAddr;
rr->TimeRcvd = 0;
rr->TimeExpire = 0;
rr->ARType = artype;
rr->AuthFlags = 0;
// Field Group 3: Transient state for Authoritative Records (set in mDNS_Register_internal)
// Field Group 4: Transient uDNS state for Authoritative Records (set in mDNS_Register_internal)
// For now, until the uDNS code is fully integrated, it's helpful to zero the uDNS state fields here too, just in case
// (e.g. uDNS_RegisterService short-circuits the usual mDNS_Register_internal record registration calls, so a bunch
// of fields don't get set up properly. In particular, if we don't zero rr->QueuedRData then the uDNS code crashes.)
rr->state = regState_Zero;
rr->uselease = 0;
rr->expire = 0;
rr->Private = 0;
rr->updateid = zeroID;
rr->zone = rr->resrec.name;
rr->nta = mDNSNULL;
rr->tcp = mDNSNULL;
rr->OrigRData = 0;
rr->OrigRDLen = 0;
rr->InFlightRData = 0;
rr->InFlightRDLen = 0;
rr->QueuedRData = 0;
rr->QueuedRDLen = 0;
mDNSPlatformMemZero(&rr->NATinfo, sizeof(rr->NATinfo));
rr->SRVChanged = mDNSfalse;
rr->mState = mergeState_Zero;
rr->namestorage.c[0] = 0; // MUST be set by client before calling mDNS_Register()
}
mDNSexport void mDNS_SetupQuestion(DNSQuestion *const q, const mDNSInterfaceID InterfaceID, const domainname *const name,
const mDNSu16 qtype, mDNSQuestionCallback *const callback, void *const context)
{
q->InterfaceID = InterfaceID;
q->flags = 0;
AssignDomainName(&q->qname, name);
q->qtype = qtype;
q->qclass = kDNSClass_IN;
q->LongLived = mDNSfalse;
q->ExpectUnique = (qtype != kDNSType_PTR);
q->ForceMCast = mDNSfalse;
q->ReturnIntermed = mDNSfalse;
q->SuppressUnusable = mDNSfalse;
q->AppendSearchDomains = 0;
q->TimeoutQuestion = 0;
q->WakeOnResolve = 0;
q->UseBackgroundTraffic = mDNSfalse;
q->ProxyQuestion = 0;
q->pid = mDNSPlatformGetPID();
q->euid = 0;
q->BlockedByPolicy = mDNSfalse;
q->ServiceID = -1;
q->QuestionCallback = callback;
q->QuestionContext = context;
}
mDNSexport mDNSu32 RDataHashValue(const ResourceRecord *const rr)
{
int len = rr->rdlength;
const RDataBody2 *const rdb = (RDataBody2 *)rr->rdata->u.data;
const mDNSu8 *ptr = rdb->data;
mDNSu32 sum = 0;
switch(rr->rrtype)
{
case kDNSType_NS:
case kDNSType_MD:
case kDNSType_MF:
case kDNSType_CNAME:
case kDNSType_MB:
case kDNSType_MG:
case kDNSType_MR:
case kDNSType_PTR:
case kDNSType_NSAP_PTR:
case kDNSType_DNAME: return DomainNameHashValue(&rdb->name);
case kDNSType_SOA: return rdb->soa.serial +
rdb->soa.refresh +
rdb->soa.retry +
rdb->soa.expire +
rdb->soa.min +
DomainNameHashValue(&rdb->soa.mname) +
DomainNameHashValue(&rdb->soa.rname);
case kDNSType_MX:
case kDNSType_AFSDB:
case kDNSType_RT:
case kDNSType_KX: return DomainNameHashValue(&rdb->mx.exchange);
case kDNSType_MINFO:
case kDNSType_RP: return DomainNameHashValue(&rdb->rp.mbox) + DomainNameHashValue(&rdb->rp.txt);
case kDNSType_PX: return DomainNameHashValue(&rdb->px.map822) + DomainNameHashValue(&rdb->px.mapx400);
case kDNSType_SRV: return DomainNameHashValue(&rdb->srv.target);
case kDNSType_OPT: return 0; // OPT is a pseudo-RR container structure; makes no sense to compare
case kDNSType_NSEC: {
int dlen;
dlen = DomainNameLength(&rdb->name);
sum = DomainNameHashValue(&rdb->name);
ptr += dlen;
len -= dlen;
fallthrough();
/* FALLTHROUGH */
}
default:
{
int i;
for (i=0; i+1 < len; i+=2)
{
sum += (((mDNSu32)(ptr[i])) << 8) | ptr[i+1];
sum = (sum<<3) | (sum>>29);
}
if (i < len)
{
sum += ((mDNSu32)(ptr[i])) << 8;
}
return(sum);
}
}
}
// r1 has to be a full ResourceRecord including rrtype and rdlength
// r2 is just a bare RDataBody, which MUST be the same rrtype and rdlength as r1
mDNSexport mDNSBool SameRDataBody(const ResourceRecord *const r1, const RDataBody *const r2, DomainNameComparisonFn *samename)
{
const RDataBody2 *const b1 = (RDataBody2 *)r1->rdata->u.data;
const RDataBody2 *const b2 = (const RDataBody2 *)r2;
switch(r1->rrtype)
{
case kDNSType_NS:
case kDNSType_MD:
case kDNSType_MF:
case kDNSType_CNAME:
case kDNSType_MB:
case kDNSType_MG:
case kDNSType_MR:
case kDNSType_PTR:
case kDNSType_NSAP_PTR:
case kDNSType_DNAME: return(SameDomainName(&b1->name, &b2->name));
case kDNSType_SOA: return (mDNSBool)( b1->soa.serial == b2->soa.serial &&
b1->soa.refresh == b2->soa.refresh &&
b1->soa.retry == b2->soa.retry &&
b1->soa.expire == b2->soa.expire &&
b1->soa.min == b2->soa.min &&
samename(&b1->soa.mname, &b2->soa.mname) &&
samename(&b1->soa.rname, &b2->soa.rname));
case kDNSType_MX:
case kDNSType_AFSDB:
case kDNSType_RT:
case kDNSType_KX: return (mDNSBool)( b1->mx.preference == b2->mx.preference &&
samename(&b1->mx.exchange, &b2->mx.exchange));
case kDNSType_MINFO:
case kDNSType_RP: return (mDNSBool)( samename(&b1->rp.mbox, &b2->rp.mbox) &&
samename(&b1->rp.txt, &b2->rp.txt));
case kDNSType_PX: return (mDNSBool)( b1->px.preference == b2->px.preference &&
samename(&b1->px.map822, &b2->px.map822) &&
samename(&b1->px.mapx400, &b2->px.mapx400));
case kDNSType_SRV: return (mDNSBool)( b1->srv.priority == b2->srv.priority &&
b1->srv.weight == b2->srv.weight &&
mDNSSameIPPort(b1->srv.port, b2->srv.port) &&
samename(&b1->srv.target, &b2->srv.target));
case kDNSType_OPT: return mDNSfalse; // OPT is a pseudo-RR container structure; makes no sense to compare
case kDNSType_NSEC: {
// If the "nxt" name changes in case, we want to delete the old
// and store just the new one. If the caller passes in SameDomainCS for "samename",
// we would return "false" when the only change between the two rdata is the case
// change in "nxt".
//
// Note: rdlength of both the RData are same (ensured by the caller) and hence we can
// use just r1->rdlength below
int dlen1 = DomainNameLength(&b1->name);
int dlen2 = DomainNameLength(&b2->name);
return (mDNSBool)(dlen1 == dlen2 &&
samename(&b1->name, &b2->name) &&
mDNSPlatformMemSame(b1->data + dlen1, b2->data + dlen2, r1->rdlength - dlen1));
}
default: return(mDNSPlatformMemSame(b1->data, b2->data, r1->rdlength));
}
}
mDNSexport mDNSBool BitmapTypeCheck(const mDNSu8 *bmap, int bitmaplen, mDNSu16 type)
{
int win, wlen;
int wintype;
// The window that this type belongs to. NSEC has 256 windows that
// comprises of 256 types.
wintype = type >> 8;
while (bitmaplen > 0)
{
if (bitmaplen < 3)
{
LogInfo("BitmapTypeCheck: malformed nsec, bitmaplen %d short", bitmaplen);
return mDNSfalse;
}
win = *bmap++;
wlen = *bmap++;
bitmaplen -= 2;
if (bitmaplen < wlen || wlen < 1 || wlen > 32)
{
LogInfo("BitmapTypeCheck: malformed nsec, bitmaplen %d wlen %d, win %d", bitmaplen, wlen, win);
return mDNSfalse;
}
if (win < 0 || win >= 256)
{
LogInfo("BitmapTypeCheck: malformed nsec, wlen %d", wlen);
return mDNSfalse;
}
if (win == wintype)
{
// First byte in the window serves 0 to 7, the next one serves 8 to 15 and so on.
// Calculate the right byte offset first.
int boff = (type & 0xff ) >> 3;
if (wlen <= boff)
return mDNSfalse;
// The last three bits values 0 to 7 corresponds to bit positions
// within the byte.
return (bmap[boff] & (0x80 >> (type & 7)));
}
else
{
// If the windows are ordered, then we could check to see
// if wintype > win and then return early.
bmap += wlen;
bitmaplen -= wlen;
}
}
return mDNSfalse;
}
// Don't call this function if the resource record is not NSEC. It will return false
// which means that the type does not exist.
mDNSexport mDNSBool RRAssertsExistence(const ResourceRecord *const rr, mDNSu16 type)
{
const RDataBody2 *const rdb = (RDataBody2 *)rr->rdata->u.data;
const mDNSu8 *nsec = rdb->data;
int len, bitmaplen;
const mDNSu8 *bmap;
if (rr->rrtype != kDNSType_NSEC) return mDNSfalse;
len = DomainNameLength(&rdb->name);
bitmaplen = rr->rdlength - len;
bmap = nsec + len;
return (BitmapTypeCheck(bmap, bitmaplen, type));
}
// Don't call this function if the resource record is not NSEC. It will return false
// which means that the type exists.
mDNSexport mDNSBool RRAssertsNonexistence(const ResourceRecord *const rr, mDNSu16 type)
{
if (rr->rrtype != kDNSType_NSEC) return mDNSfalse;
return !RRAssertsExistence(rr, type);
}
mDNSexport mDNSBool RRTypeAnswersQuestionType(const ResourceRecord *const rr, const mDNSu16 qtype,
const RRTypeAnswersQuestionTypeFlags flags)
{
#if MDNSRESPONDER_SUPPORTS(APPLE, DNSSECv2)
// This checks if the record is what the question requires:
// 1. If the question does not enable DNSSEC, either "DNSSEC to be validated" nor "DNSSEC validated" record answers it.
// 2. If the question enables DNSSEC, and it is not a duplicate question, it needs both "DNSSEC to be validated" nor "DNSSEC validated" records:
// a. Get "DNSSEC to be validated" to do DNSSEC validation.
// b. Get "DNSSEC validated" to return to the client.
// 3. If the question enables DNSSEC, and it is a duplicate question, it only needs "DNSSEC validated" records:
// a. Does not need "DNSSEC to be validated" because the non-duplicate question will do the validation.
// b. Get "DNSSEC validated" to return to the client.
const mDNSBool requiresRRToValidate = ((flags & kRRTypeAnswersQuestionTypeFlagsRequiresDNSSECRRToValidate) != 0);
const mDNSBool requiresValidatedRR = ((flags & kRRTypeAnswersQuestionTypeFlagsRequiresDNSSECRRValidated) != 0);
if (!resource_record_answers_dnssec_question_request_type(rr, requiresRRToValidate, requiresValidatedRR))
{
return mDNSfalse;
}
#else
(void) flags;
#endif
// OPT should not answer any questions.
if (rr->rrtype == kDNSType_OPT)
{
return mDNSfalse;
}
// CNAME answers any questions, except negative CNAME. (this function is not responsible to check that)
if (rr->rrtype == kDNSType_CNAME)
{
return mDNStrue;
}
// The most usual case where the record type matches the question type.
if (rr->rrtype == qtype)
{
return mDNStrue;
}
// If question asks for any DNS record type, then any record type can answer this question.
if (qtype == kDNSQType_ANY)
{
return mDNStrue;
}
// If the mDNS NSEC record asserts the nonexistence of the question type, then it answers the question type
// negatively.
if (MULTICAST_NSEC(rr) && RRAssertsNonexistence(rr, qtype))
{
return mDNStrue;
}
#if MDNSRESPONDER_SUPPORTS(APPLE, DNSSECv2)
// The type covered of RRSIG should match the non-duplicate DNSSEC question type, because RRSIG will be used by it
// to do DNSSEC validation.
if (resource_record_as_rrsig_answers_dnssec_question_type(rr, qtype))
{
return mDNStrue;
}
#endif
return mDNSfalse;
}
#if MDNSRESPONDER_SUPPORTS(APPLE, QUERIER)
mDNSlocal mDNSBool RRMatchesQuestionService(const ResourceRecord *const rr, const DNSQuestion *const q)
{
return mdns_cache_metadata_get_dns_service(rr->metadata) == q->dnsservice;
}
#endif
mDNSlocal mDNSBool RRIsResolvedBymDNS(const ResourceRecord *const rr)
{
#if MDNSRESPONDER_SUPPORTS(APPLE, QUERIER)
if (mdns_cache_metadata_get_dns_service(rr->metadata))
{
return mDNSfalse;
}
#endif
return (rr->InterfaceID != 0);
}
// ResourceRecordAnswersQuestion returns mDNStrue if the given resource record is a valid answer to the given question.
// SameNameRecordAnswersQuestion is the same, except it skips the expensive SameDomainName() call.
// SameDomainName() is generally cheap when the names don't match, but expensive when they do match,
// because it has to check all the way to the end of the names to be sure.
// In cases where we know in advance that the names match it's especially advantageous to skip the
// SameDomainName() call because that's precisely the time when it's most expensive and least useful.
mDNSlocal mDNSBool SameNameRecordAnswersQuestion(const ResourceRecord *const rr, mDNSBool isAuthRecord, const DNSQuestion *const q)
{
// LocalOnly/P2P questions can be answered with AuthRecordAny in this function. LocalOnly/P2P records
// are handled in LocalOnlyRecordAnswersQuestion
if (LocalOnlyOrP2PInterface(rr->InterfaceID))
{
LogMsg("SameNameRecordAnswersQuestion: ERROR!! called with LocalOnly ResourceRecord %p, Question %p", rr->InterfaceID, q->InterfaceID);
return mDNSfalse;
}
if (q->Suppressed && (!q->ForceCNAMEFollows || (rr->rrtype != kDNSType_CNAME)))
return mDNSfalse;
if (rr->InterfaceID &&
q->InterfaceID && q->InterfaceID != mDNSInterface_LocalOnly &&
rr->InterfaceID != q->InterfaceID) return(mDNSfalse);
#if MDNSRESPONDER_SUPPORTS(APPLE, TERMINUS_ASSISTED_UNICAST_DISCOVERY)
if (DNSQuestionUsesMDNSAlternativeService(q))
{
if (!RRMatchesQuestionService(rr, q))
{
return mDNSfalse;
}
}
else
#endif
{
const mDNSBool resolvedBymDNS = RRIsResolvedBymDNS(rr);
mDNSBool ismDNSQuestion = mDNSOpaque16IsZero(q->TargetQID);
// If the record is resolved via the non-mDNS channel, the server or service used should match.
if (!isAuthRecord && !resolvedBymDNS)
{
if (ismDNSQuestion)
{
return mDNSfalse;
}
#if MDNSRESPONDER_SUPPORTS(APPLE, QUERIER)
if (!RRMatchesQuestionService(rr, q)) return(mDNSfalse);
#else
const mDNSu32 idr = rr->rDNSServer ? rr->rDNSServer->resGroupID : 0;
const mDNSu32 idq = q->qDNSServer ? q->qDNSServer->resGroupID : 0;
if (idr != idq) return(mDNSfalse);
#endif
}
// mDNS records can only be used to answer mDNS questions.
if (resolvedBymDNS && !ismDNSQuestion)
{
return mDNSfalse;
}
}
// CNAME answers question of any type and a negative cache record should not prevent us from querying other
// valid types at the same name.
if (rr->rrtype == kDNSType_CNAME && rr->RecordType == kDNSRecordTypePacketNegative && rr->rrtype != q->qtype)
return mDNSfalse;
// RR type CNAME matches any query type. QTYPE ANY matches any RR type. QCLASS ANY matches any RR class.
RRTypeAnswersQuestionTypeFlags flags = kRRTypeAnswersQuestionTypeFlagsNone;
#if MDNSRESPONDER_SUPPORTS(APPLE, DNSSECv2)
// Primary DNSSEC requestor is the non-duplicate DNSSEC question that does the DNSSEC validation, therefore, it needs
// the "DNSSEC to be validated" record. (It is also DNSSEC requestor, see below)
if (dns_question_is_primary_dnssec_requestor(q))
{
flags |= kRRTypeAnswersQuestionTypeFlagsRequiresDNSSECRRToValidate;
}
// DNSSEC requestor is the DNSSEC question that needs DNSSEC validated result.
if (dns_question_is_dnssec_requestor(q))
{
flags |= kRRTypeAnswersQuestionTypeFlagsRequiresDNSSECRRValidated;
}
#endif
const mDNSBool typeMatches = RRTypeAnswersQuestionType(rr, q->qtype, flags);
if (!typeMatches)
{
return(mDNSfalse);
}
if (rr->rrclass != q->qclass && q->qclass != kDNSQClass_ANY) return(mDNSfalse);
return(mDNStrue);
}
mDNSexport mDNSBool SameNameCacheRecordAnswersQuestion(const CacheRecord *const cr, const DNSQuestion *const q)
{
return SameNameRecordAnswersQuestion(&cr->resrec, mDNSfalse, q);
}
mDNSlocal mDNSBool RecordAnswersQuestion(const ResourceRecord *const rr, mDNSBool isAuthRecord, const DNSQuestion *const q)
{
if (!SameNameRecordAnswersQuestion(rr, isAuthRecord, q))
return mDNSfalse;
return(rr->namehash == q->qnamehash && SameDomainName(rr->name, &q->qname));
}
mDNSexport mDNSBool ResourceRecordAnswersQuestion(const ResourceRecord *const rr, const DNSQuestion *const q)
{
return RecordAnswersQuestion(rr, mDNSfalse, q);
}
mDNSexport mDNSBool AuthRecordAnswersQuestion(const AuthRecord *const ar, const DNSQuestion *const q)
{
return RecordAnswersQuestion(&ar->resrec, mDNStrue, q);
}
mDNSexport mDNSBool CacheRecordAnswersQuestion(const CacheRecord *const cr, const DNSQuestion *const q)
{
return RecordAnswersQuestion(&cr->resrec, mDNSfalse, q);
}
// We have a separate function to handle LocalOnly AuthRecords because they can be created with
// a valid InterfaceID (e.g., scoped /etc/hosts) and can be used to answer unicast questions unlike
// multicast resource records (which has a valid InterfaceID) which can't be used to answer
// unicast questions. ResourceRecordAnswersQuestion/SameNameRecordAnswersQuestion can't tell whether
// a resource record is multicast or LocalOnly by just looking at the ResourceRecord because
// LocalOnly records are truly identified by ARType in the AuthRecord. As P2P and LocalOnly record
// are kept in the same hash table, we use the same function to make it easy for the callers when
// they walk the hash table to answer LocalOnly/P2P questions
//
mDNSexport mDNSBool LocalOnlyRecordAnswersQuestion(AuthRecord *const ar, const DNSQuestion *const q)
{
ResourceRecord *rr = &ar->resrec;
// mDNSInterface_Any questions can be answered with LocalOnly/P2P records in this function. AuthRecord_Any
// records are handled in ResourceRecordAnswersQuestion/SameNameRecordAnswersQuestion
if (RRAny(ar))
{
LogMsg("LocalOnlyRecordAnswersQuestion: ERROR!! called with regular AuthRecordAny %##s", rr->name->c);
return mDNSfalse;
}
// Questions with mDNSInterface_LocalOnly InterfaceID should be answered with all resource records that are
// *local* to the machine. These include resource records that have InterfaceID set to mDNSInterface_LocalOnly,
// mDNSInterface_Any and any other real InterfaceID. Hence, LocalOnly questions should not be checked against
// the InterfaceID in the resource record.
if (rr->InterfaceID &&
q->InterfaceID != mDNSInterface_LocalOnly &&
((q->InterfaceID && rr->InterfaceID != q->InterfaceID) ||
(!q->InterfaceID && !LocalOnlyOrP2PInterface(rr->InterfaceID)))) return(mDNSfalse);
// Entries in /etc/hosts are added as LocalOnly resource records. The LocalOnly resource records
// may have a scope e.g., fe80::1%en0. The question may be scoped or not: the InterfaceID may be set
// to mDNSInterface_Any, mDNSInterface_LocalOnly or a real InterfaceID (scoped).
//
// 1) Question: Any, LocalOnly Record: no scope. This question should be answered with this record.
//
// 2) Question: Any, LocalOnly Record: scoped. This question should be answered with the record because
// traditionally applications never specify scope e.g., getaddrinfo, but need to be able
// to get to /etc/hosts entries.
//
// 3) Question: Scoped (LocalOnly or InterfaceID), LocalOnly Record: no scope. This is the inverse of (2).
// If we register a LocalOnly record, we need to answer a LocalOnly question. If the /etc/hosts has a
// non scoped entry, it may not make sense to answer a scoped question. But we can't tell these two
// cases apart. As we currently answer LocalOnly question with LocalOnly record, we continue to do so.
//
// 4) Question: Scoped (LocalOnly or InterfaceID), LocalOnly Record: scoped. LocalOnly questions should be
// answered with any resource record where as if it has a valid InterfaceID, the scope should match.
//
// (1) and (2) is bypassed because we check for a non-NULL InterfaceID above. For (3), the InterfaceID is NULL
// and hence bypassed above. For (4) we bypassed LocalOnly questions and checked the scope of the record
// against the question.
//
// For P2P, InterfaceIDs of the question and the record should match.
// If ResourceRecord received via multicast, but question was unicast, then shouldn't use record to answer this question.
// LocalOnly authoritative answers are exempt. LocalOnly authoritative answers are used for /etc/host entries.
// We don't want a local process to be able to create a fake LocalOnly address record for "www.bigbank.com" which would then
// cause other applications (e.g. Safari) to connect to the wrong address. The rpc to register records filters out records
// with names that don't end in local and have mDNSInterface_LocalOnly set.
//
// Note: The check is bypassed for LocalOnly and for P2P it is not needed as only .local records are registered and for
// a question to match its names, it also has to end in .local and that question can't be a unicast question (See
// Question_uDNS macro and its usage). As P2P does not enforce .local only registrations we still make this check
// and also makes it future proof.
if (ar->ARType != AuthRecordLocalOnly && rr->InterfaceID && !mDNSOpaque16IsZero(q->TargetQID)) return(mDNSfalse);
#if MDNSRESPONDER_SUPPORTS(APPLE, DNSSECv2)
// No local only record can answer DNSSEC question.
if (dns_question_is_dnssec_requestor(q))
{
return mDNSfalse;
}
#endif
// RR type CNAME matches any query type. QTYPE ANY matches any RR type. QCLASS ANY matches any RR class.
RRTypeAnswersQuestionTypeFlags flags = kRRTypeAnswersQuestionTypeFlagsNone;
const mDNSBool typeMatches = RRTypeAnswersQuestionType(rr, q->qtype, flags);
if (!typeMatches)
{
return mDNSfalse;
}
if (rr->rrclass != q->qclass && q->qclass != kDNSQClass_ANY) return(mDNSfalse);
return(rr->namehash == q->qnamehash && SameDomainName(rr->name, &q->qname));
}
mDNSexport mDNSBool AnyTypeRecordAnswersQuestion(const AuthRecord *const ar, const DNSQuestion *const q)
{
const ResourceRecord *const rr = &ar->resrec;
// LocalOnly/P2P questions can be answered with AuthRecordAny in this function. LocalOnly/P2P records
// are handled in LocalOnlyRecordAnswersQuestion
if (LocalOnlyOrP2PInterface(rr->InterfaceID))
{
LogMsg("AnyTypeRecordAnswersQuestion: ERROR!! called with LocalOnly ResourceRecord %p, Question %p", rr->InterfaceID, q->InterfaceID);
return mDNSfalse;
}
if (rr->InterfaceID &&
q->InterfaceID && q->InterfaceID != mDNSInterface_LocalOnly &&
rr->InterfaceID != q->InterfaceID) return(mDNSfalse);
#if MDNSRESPONDER_SUPPORTS(APPLE, TERMINUS_ASSISTED_UNICAST_DISCOVERY)
if (DNSQuestionUsesMDNSAlternativeService(q))
{
if (!RRMatchesQuestionService(rr, q))
{
return mDNSfalse;
}
}
else
#endif
{
const mDNSBool resolvedByMDNS = RRIsResolvedBymDNS(rr);
// Resource record received via non-mDNS channel, the server or service should match.
// Note that Auth Records are normally setup with NULL InterfaceID and
// both the DNSServers are assumed to be NULL in that case
if (!resolvedByMDNS)
{
#if MDNSRESPONDER_SUPPORTS(APPLE, QUERIER)
if (!RRMatchesQuestionService(rr, q)) return(mDNSfalse);
#else
const mDNSu32 idr = rr->rDNSServer ? rr->rDNSServer->resGroupID : 0;
const mDNSu32 idq = q->qDNSServer ? q->qDNSServer->resGroupID : 0;
if (idr != idq) return(mDNSfalse);
#endif
#if MDNSRESPONDER_SUPPORTS(APPLE, RANDOM_AWDL_HOSTNAME)
if (!mDNSPlatformValidRecordForInterface(ar, q->InterfaceID)) return(mDNSfalse);
#endif
}
// mDNS records can only be used to answer mDNS questions.
const mDNSBool isMDNSQuestion = mDNSOpaque16IsZero(q->TargetQID);
if (resolvedByMDNS && !isMDNSQuestion)
{
return mDNSfalse;
}
}
if (rr->rrclass != q->qclass && q->qclass != kDNSQClass_ANY) return(mDNSfalse);
return(rr->namehash == q->qnamehash && SameDomainName(rr->name, &q->qname));
}
// This is called with both unicast resource record and multicast resource record. The question that
// received the unicast response could be the regular unicast response from a DNS server or a response
// to a mDNS QU query. The main reason we need this function is that we can't compare DNSServers between the
// question and the resource record because the resource record is not completely initialized in
// mDNSCoreReceiveResponse when this function is called.
mDNSexport mDNSBool ResourceRecordAnswersUnicastResponse(const ResourceRecord *const rr, const DNSQuestion *const q)
{
if (q->Suppressed)
return mDNSfalse;
// For resource records created using multicast or DNS push, the InterfaceIDs have to match.
if (rr->InterfaceID &&
q->InterfaceID && rr->InterfaceID != q->InterfaceID) return(mDNSfalse);
// If record is resolved by mDNS, but question is non-mDNS, then should not use it to answer this question.
const mDNSBool resolvedByMDNS = RRIsResolvedBymDNS(rr);
const mDNSBool isMDNSQuestion = mDNSOpaque16IsZero(q->TargetQID);
if (resolvedByMDNS && !isMDNSQuestion)
{
return mDNSfalse;
}
// RR type CNAME matches any query type. QTYPE ANY matches any RR type. QCLASS ANY matches any RR class.
RRTypeAnswersQuestionTypeFlags flags = kRRTypeAnswersQuestionTypeFlagsNone;
#if MDNSRESPONDER_SUPPORTS(APPLE, DNSSECv2)
// Thus routine is only used for the records received from internet. Right now, we will not receive DNSSEC validated
// record from wire (ODoH will probably give us validated records in the future?). Therefore, we only need to check
// if the record answers primary DNSSEC requestor and can be used for validation.
if (dns_question_is_primary_dnssec_requestor(q))
{
flags |= kRRTypeAnswersQuestionTypeFlagsRequiresDNSSECRRToValidate;
}
#endif
const mDNSBool typeMatches = RRTypeAnswersQuestionType(rr, q->qtype, flags);
if (!typeMatches)
{
return(mDNSfalse);
}
if (rr->rrclass != q->qclass && q->qclass != kDNSQClass_ANY) return(mDNSfalse);
return(rr->namehash == q->qnamehash && SameDomainName(rr->name, &q->qname));
}
mDNSexport mDNSu16 GetRDLength(const ResourceRecord *const rr, mDNSBool estimate)
{
const RDataBody2 *const rd = (RDataBody2 *)rr->rdata->u.data;
const domainname *const name = estimate ? rr->name : mDNSNULL;
if (rr->rrclass == kDNSQClass_ANY) return(rr->rdlength); // Used in update packets to mean "Delete An RRset" (RFC 2136)
else switch (rr->rrtype)
{
case kDNSType_A: return(sizeof(rd->ipv4));
case kDNSType_NS:
case kDNSType_CNAME:
case kDNSType_PTR:
case kDNSType_DNAME: return(CompressedDomainNameLength(&rd->name, name));
case kDNSType_SOA: return (mDNSu16)(CompressedDomainNameLength(&rd->soa.mname, name) +
CompressedDomainNameLength(&rd->soa.rname, name) +
5 * sizeof(mDNSOpaque32));
case kDNSType_NULL:
case kDNSType_TSIG:
case kDNSType_TXT:
case kDNSType_X25:
case kDNSType_ISDN:
case kDNSType_LOC:
case kDNSType_DHCID: return(rr->rdlength); // Not self-describing, so have to just trust rdlength
case kDNSType_HINFO: return (mDNSu16)(2 + (int)rd->data[0] + (int)rd->data[1 + (int)rd->data[0]]);
case kDNSType_MX:
case kDNSType_AFSDB:
case kDNSType_RT:
case kDNSType_KX: return (mDNSu16)(2 + CompressedDomainNameLength(&rd->mx.exchange, name));
case kDNSType_MINFO:
case kDNSType_RP: return (mDNSu16)(CompressedDomainNameLength(&rd->rp.mbox, name) +
CompressedDomainNameLength(&rd->rp.txt, name));
case kDNSType_PX: return (mDNSu16)(2 + CompressedDomainNameLength(&rd->px.map822, name) +
CompressedDomainNameLength(&rd->px.mapx400, name));
case kDNSType_AAAA: return(sizeof(rd->ipv6));
case kDNSType_SRV: return (mDNSu16)(6 + CompressedDomainNameLength(&rd->srv.target, name));
case kDNSType_OPT: return(rr->rdlength);
case kDNSType_NSEC:
{
const domainname *const next = (const domainname *)rd->data;
const int dlen = DomainNameLength(next);
if (MULTICAST_NSEC(rr))
{
return (mDNSu16)((estimate ? 2 : dlen) + rr->rdlength - dlen);
}
else
{
// Unicast NSEC does not do name compression. Therefore, we can return `rdlength` directly.
// See [RFC 4034 4.1.1.](https://datatracker.ietf.org/doc/html/rfc4034#section-4.1.1).
return rr->rdlength;
}
}
case kDNSType_TSR: return(sizeof(rd->tsr_value));
default: debugf("Warning! Don't know how to get length of resource type %d", rr->rrtype);
return(rr->rdlength);
}
}
// When a local client registers (or updates) a record, we use this routine to do some simple validation checks
// to help reduce the risk of bogus malformed data on the network
mDNSexport mDNSBool ValidateRData(const mDNSu16 rrtype, const mDNSu16 rdlength, const RData *const rd)
{
mDNSu16 len;
switch(rrtype)
{
case kDNSType_A: return(rdlength == sizeof(mDNSv4Addr));
case kDNSType_NS: // Same as PTR
case kDNSType_MD: // Same as PTR
case kDNSType_MF: // Same as PTR
case kDNSType_CNAME: // Same as PTR
//case kDNSType_SOA not checked
case kDNSType_MB: // Same as PTR
case kDNSType_MG: // Same as PTR
case kDNSType_MR: // Same as PTR
//case kDNSType_NULL not checked (no specified format, so always valid)
//case kDNSType_WKS not checked
case kDNSType_PTR: len = DomainNameLengthLimit(&rd->u.name, rd->u.data + rdlength);
return(len <= MAX_DOMAIN_NAME && rdlength == len);
case kDNSType_HINFO: // Same as TXT (roughly)
case kDNSType_MINFO: // Same as TXT (roughly)
case kDNSType_TXT: if (!rdlength) return(mDNSfalse); // TXT record has to be at least one byte (RFC 1035)
{
const mDNSu8 *ptr = rd->u.txt.c;
const mDNSu8 *end = rd->u.txt.c + rdlength;
while (ptr < end) ptr += 1 + ptr[0];
return (ptr == end);
}
case kDNSType_AAAA: return(rdlength == sizeof(mDNSv6Addr));
case kDNSType_MX: // Must be at least two-byte preference, plus domainname
// Call to DomainNameLengthLimit() implicitly enforces both requirements for us
len = DomainNameLengthLimit(&rd->u.mx.exchange, rd->u.data + rdlength);
return(len <= MAX_DOMAIN_NAME && rdlength == 2+len);
case kDNSType_SRV: // Must be at least priority+weight+port, plus domainname
// Call to DomainNameLengthLimit() implicitly enforces both requirements for us
len = DomainNameLengthLimit(&rd->u.srv.target, rd->u.data + rdlength);
return(len <= MAX_DOMAIN_NAME && rdlength == 6+len);
//case kDNSType_NSEC not checked
default: return(mDNStrue); // Allow all other types without checking
}
}
mDNSexport const mDNSu8 * ResourceRecordGetRDataBytesPointer(const ResourceRecord *const rr,
mDNSu8 * const bytesBuffer, const mDNSu16 bufferSize, mDNSu16 *const outRDataLen, mStatus *const outError)
{
mStatus err;
const mDNSu8 *rdataBytes = mDNSNULL;
mDNSu16 rdataLen = 0;
switch (rr->rrtype)
{
case kDNSType_SOA:
case kDNSType_MX:
case kDNSType_AFSDB:
case kDNSType_RT:
case kDNSType_RP:
case kDNSType_SRV:
case kDNSType_PX:
case kDNSType_KX:
case kDNSType_OPT:
case kDNSType_NSEC:
case kDNSType_TSR:
{
const mDNSu8 *const rdataBytesEnd = putRData(mDNSNULL, bytesBuffer, bytesBuffer + bufferSize, rr);
mdns_require_action_quiet(rdataBytesEnd && (rdataBytesEnd > bytesBuffer), exit, err = mStatus_BadParamErr);
rdataBytes = bytesBuffer;
rdataLen = (rdataBytesEnd - bytesBuffer);
break;
}
default:
rdataBytes = rr->rdata->u.data;
rdataLen = rr->rdlength;
break;
}
err = mStatus_NoError;
exit:
mdns_assign(outRDataLen, rdataLen);
mdns_assign(outError, err);
return rdataBytes;
}
// ***************************************************************************
// MARK: - DNS Message Creation Functions
mDNSexport void InitializeDNSMessage(DNSMessageHeader *h, mDNSOpaque16 id, mDNSOpaque16 flags)
{
h->id = id;
h->flags = flags;
h->numQuestions = 0;
h->numAnswers = 0;
h->numAuthorities = 0;
h->numAdditionals = 0;
}
#endif // !STANDALONE
mDNSexport const mDNSu8 *FindCompressionPointer(const mDNSu8 *const base, const mDNSu8 *const end, const mDNSu8 *const domname)
{
const mDNSu8 *result = end - *domname - 1;
if (*domname == 0) return(mDNSNULL); // There's no point trying to match just the root label
// This loop examines each possible starting position in packet, starting end of the packet and working backwards
while (result >= base)
{
// If the length byte and first character of the label match, then check further to see
// if this location in the packet will yield a useful name compression pointer.
if (result[0] == domname[0] && result[1] == domname[1])
{
const mDNSu8 *name = domname;
const mDNSu8 *targ = result;
while (targ + *name < end)
{
// First see if this label matches
int i;
const mDNSu8 *pointertarget;
for (i=0; i <= *name; i++) if (targ[i] != name[i]) break;
if (i <= *name) break; // If label did not match, bail out
targ += 1 + *name; // Else, did match, so advance target pointer
name += 1 + *name; // and proceed to check next label
if (*name == 0 && *targ == 0) return(result); // If no more labels, we found a match!
if (*name == 0) break; // If no more labels to match, we failed, so bail out
// The label matched, so now follow the pointer (if appropriate) and then see if the next label matches
if (targ[0] < 0x40) continue; // If length value, continue to check next label
if (targ[0] < 0xC0) break; // If 40-BF, not valid
if (targ+1 >= end) break; // Second byte not present!
pointertarget = base + (((mDNSu16)(targ[0] & 0x3F)) << 8) + targ[1];
if (targ < pointertarget) break; // Pointertarget must point *backwards* in the packet
if (pointertarget[0] >= 0x40) break; // Pointertarget must point to a valid length byte
targ = pointertarget;
}
}
result--; // We failed to match at this search position, so back up the tentative result pointer and try again
}
return(mDNSNULL);
}
// domainname is a fully-qualified name (i.e. assumed to be ending in a dot, even if it doesn't)
// msg points to the message we're building (pass mDNSNULL if we don't want to use compression pointers)
// end points to the end of the message so far
// ptr points to where we want to put the name
// limit points to one byte past the end of the buffer that we must not overrun
// domainname is the name to put
mDNSexport mDNSu8 *putDomainNameAsLabels(const DNSMessage *const msg,
mDNSu8 *ptr, const mDNSu8 *const limit, const domainname *const name)
{
const mDNSu8 *const base = (const mDNSu8 *)msg;
const mDNSu8 * np = name->c;
const mDNSu8 *const max = name->c + MAX_DOMAIN_NAME; // Maximum that's valid
const mDNSu8 * pointer = mDNSNULL;
const mDNSu8 *const searchlimit = ptr;
if (!ptr) { LogMsg("putDomainNameAsLabels %##s ptr is null", name->c); return(mDNSNULL); }
if (!*np) // If just writing one-byte root label, make sure we have space for that
{
if (ptr >= limit) return(mDNSNULL);
}
else // else, loop through writing labels and/or a compression offset
{
do {
if (*np > MAX_DOMAIN_LABEL)
{ LogMsg("Malformed domain name %##s (label more than 63 bytes)", name->c); return(mDNSNULL); }
// This check correctly allows for the final trailing root label:
// e.g.
// Suppose our domain name is exactly 256 bytes long, including the final trailing root label.
// Suppose np is now at name->c[249], and we're about to write our last non-null label ("local").
// We know that max will be at name->c[256]
// That means that np + 1 + 5 == max - 1, so we (just) pass the "if" test below, write our
// six bytes, then exit the loop, write the final terminating root label, and the domain
// name we've written is exactly 256 bytes long, exactly at the correct legal limit.
// If the name is one byte longer, then we fail the "if" test below, and correctly bail out.
if (np + 1 + *np >= max)
{ LogMsg("Malformed domain name %##s (more than 256 bytes)", name->c); return(mDNSNULL); }
if (base) pointer = FindCompressionPointer(base, searchlimit, np);
if (pointer) // Use a compression pointer if we can
{
const mDNSu16 offset = (mDNSu16)(pointer - base);
if (ptr+2 > limit) return(mDNSNULL); // If we don't have two bytes of space left, give up
*ptr++ = (mDNSu8)(0xC0 | (offset >> 8));
*ptr++ = (mDNSu8)( offset & 0xFF);
return(ptr);
}
else // Else copy one label and try again
{
int i;
mDNSu8 len = *np++;
// If we don't at least have enough space for this label *plus* a terminating zero on the end, give up
if (ptr + 1 + len >= limit) return(mDNSNULL);
*ptr++ = len;
for (i=0; i<len; i++) *ptr++ = *np++;
}
} while (*np); // While we've got characters remaining in the name, continue
}
*ptr++ = 0; // Put the final root label
return(ptr);
}
#ifndef STANDALONE
mDNSlocal mDNSu8 *putVal16(mDNSu8 *ptr, mDNSu16 val)
{
ptr[0] = (mDNSu8)((val >> 8 ) & 0xFF);
ptr[1] = (mDNSu8)((val ) & 0xFF);
return ptr + sizeof(mDNSOpaque16);
}
mDNSlocal mDNSu8 *putVal32(mDNSu8 *ptr, mDNSu32 val)
{
ptr[0] = (mDNSu8)((val >> 24) & 0xFF);
ptr[1] = (mDNSu8)((val >> 16) & 0xFF);
ptr[2] = (mDNSu8)((val >> 8) & 0xFF);
ptr[3] = (mDNSu8)((val ) & 0xFF);
return ptr + sizeof(mDNSu32);
}
// Copy the RDATA information. The actual in memory storage for the data might be bigger than what the rdlength
// says. Hence, the only way to copy out the data from a resource record is to use putRData.
// msg points to the message we're building (pass mDNSNULL for "msg" if we don't want to use compression pointers)
mDNSexport mDNSu8 *putRData(const DNSMessage *const msg, mDNSu8 *ptr, const mDNSu8 *const limit, const ResourceRecord *const rr)
{
const RDataBody2 *const rdb = (RDataBody2 *)rr->rdata->u.data;
switch (rr->rrtype)
{
case kDNSType_A: if (rr->rdlength != 4)
{ debugf("putRData: Illegal length %d for kDNSType_A", rr->rdlength); return(mDNSNULL); }
if (ptr + 4 > limit) return(mDNSNULL);
*ptr++ = rdb->ipv4.b[0];
*ptr++ = rdb->ipv4.b[1];
*ptr++ = rdb->ipv4.b[2];
*ptr++ = rdb->ipv4.b[3];
return(ptr);
case kDNSType_NS:
case kDNSType_CNAME:
case kDNSType_PTR:
case kDNSType_DNAME: return(putDomainNameAsLabels(msg, ptr, limit, &rdb->name));
case kDNSType_SOA: ptr = putDomainNameAsLabels(msg, ptr, limit, &rdb->soa.mname);
if (!ptr) return(mDNSNULL);
ptr = putDomainNameAsLabels(msg, ptr, limit, &rdb->soa.rname);
if (!ptr || ptr + 20 > limit) return(mDNSNULL);
ptr = putVal32(ptr, rdb->soa.serial);
ptr = putVal32(ptr, rdb->soa.refresh);
ptr = putVal32(ptr, rdb->soa.retry);
ptr = putVal32(ptr, rdb->soa.expire);
ptr = putVal32(ptr, rdb->soa.min);
return(ptr);
case kDNSType_NULL:
case kDNSType_HINFO:
case kDNSType_TSIG:
case kDNSType_TXT:
case kDNSType_X25:
case kDNSType_ISDN:
case kDNSType_LOC:
case kDNSType_DHCID: if (ptr + rr->rdlength > limit) return(mDNSNULL);
mDNSPlatformMemCopy(ptr, rdb->data, rr->rdlength);
return(ptr + rr->rdlength);
case kDNSType_MX:
case kDNSType_AFSDB:
case kDNSType_RT:
case kDNSType_KX: if (ptr + 3 > limit) return(mDNSNULL);
ptr = putVal16(ptr, rdb->mx.preference);
return(putDomainNameAsLabels(msg, ptr, limit, &rdb->mx.exchange));
case kDNSType_RP: ptr = putDomainNameAsLabels(msg, ptr, limit, &rdb->rp.mbox);
if (!ptr) return(mDNSNULL);
ptr = putDomainNameAsLabels(msg, ptr, limit, &rdb->rp.txt);
return(ptr);
case kDNSType_PX: if (ptr + 5 > limit) return(mDNSNULL);
ptr = putVal16(ptr, rdb->px.preference);
ptr = putDomainNameAsLabels(msg, ptr, limit, &rdb->px.map822);
if (!ptr) return(mDNSNULL);
ptr = putDomainNameAsLabels(msg, ptr, limit, &rdb->px.mapx400);
return(ptr);
case kDNSType_AAAA: if (rr->rdlength != sizeof(rdb->ipv6))
{ debugf("putRData: Illegal length %d for kDNSType_AAAA", rr->rdlength); return(mDNSNULL); }
if (ptr + sizeof(rdb->ipv6) > limit) return(mDNSNULL);
mDNSPlatformMemCopy(ptr, &rdb->ipv6, sizeof(rdb->ipv6));
return(ptr + sizeof(rdb->ipv6));
case kDNSType_SRV: if (ptr + 7 > limit) return(mDNSNULL);
*ptr++ = (mDNSu8)(rdb->srv.priority >> 8);
*ptr++ = (mDNSu8)(rdb->srv.priority & 0xFF);
*ptr++ = (mDNSu8)(rdb->srv.weight >> 8);
*ptr++ = (mDNSu8)(rdb->srv.weight & 0xFF);
*ptr++ = rdb->srv.port.b[0];
*ptr++ = rdb->srv.port.b[1];
return(putDomainNameAsLabels(msg, ptr, limit, &rdb->srv.target));
case kDNSType_TSR: {
// tsr timestamp on wire is relative time since received.
mDNSs32 tsr_relative = mDNSPlatformContinuousTimeSeconds() - rdb->tsr_value;
ptr = putVal32(ptr, tsr_relative);
return(ptr);
}
case kDNSType_OPT: {
int len = 0;
const rdataOPT *opt;
const rdataOPT *const end = (const rdataOPT *)&rr->rdata->u.data[rr->rdlength];
for (opt = &rr->rdata->u.opt[0]; opt < end; opt++)
len += DNSOpt_Data_Space(opt);
if (ptr + len > limit)
{
LogMsg("ERROR: putOptRData - out of space");
return mDNSNULL;
}
for (opt = &rr->rdata->u.opt[0]; opt < end; opt++)
{
const int space = DNSOpt_Data_Space(opt);
ptr = putVal16(ptr, opt->opt);
ptr = putVal16(ptr, (mDNSu16)space - 4);
switch (opt->opt)
{
case kDNSOpt_LLQ:
ptr = putVal16(ptr, opt->u.llq.vers);
ptr = putVal16(ptr, opt->u.llq.llqOp);
ptr = putVal16(ptr, opt->u.llq.err);
mDNSPlatformMemCopy(ptr, opt->u.llq.id.b, 8); // 8-byte id
ptr += 8;
ptr = putVal32(ptr, opt->u.llq.llqlease);
break;
case kDNSOpt_Lease:
ptr = putVal32(ptr, opt->u.updatelease);
break;
case kDNSOpt_Owner:
*ptr++ = opt->u.owner.vers;
*ptr++ = opt->u.owner.seq;
mDNSPlatformMemCopy(ptr, opt->u.owner.HMAC.b, 6); // 6-byte Host identifier
ptr += 6;
if (space >= DNSOpt_OwnerData_ID_Wake_Space)
{
mDNSPlatformMemCopy(ptr, opt->u.owner.IMAC.b, 6); // 6-byte interface MAC
ptr += 6;
if (space > DNSOpt_OwnerData_ID_Wake_Space)
{
mDNSPlatformMemCopy(ptr, opt->u.owner.password.b, space - DNSOpt_OwnerData_ID_Wake_Space);
ptr += space - DNSOpt_OwnerData_ID_Wake_Space;
}
}
break;
case kDNSOpt_Trace:
*ptr++ = opt->u.tracer.platf;
ptr = putVal32(ptr, opt->u.tracer.mDNSv);
break;
case kDNSOpt_TSR:
{
mDNSs32 tsr_relative = mDNSPlatformContinuousTimeSeconds() - opt->u.tsr.timeStamp;
ptr = putVal32(ptr, tsr_relative);
ptr = putVal32(ptr, opt->u.tsr.hostkeyHash);
ptr = putVal16(ptr, opt->u.tsr.recIndex);
}
break;
default:
break;
}
}
return ptr;
}
case kDNSType_NSEC: {
// For NSEC records, rdlength represents the exact number of bytes
// of in memory storage.
const mDNSu8 *nsec = (const mDNSu8 *)rdb->data;
const domainname *name = (const domainname *)nsec;
const int dlen = DomainNameLength(name);
nsec += dlen;
// This function is called when we are sending a NSEC record as part of mDNS,
// or to copy the data to any other buffer needed which could be a mDNS or uDNS
// NSEC record. The only time compression is used that when we are sending it
// in mDNS (indicated by non-NULL "msg") and hence we handle mDNS case
// separately.
if (MULTICAST_NSEC(rr))
{
mDNSu8 *save = ptr;
int i, j, wlen;
wlen = *(nsec + 1);
nsec += 2; // Skip the window number and len
// For our simplified use of NSEC synthetic records:
//
// nextname is always the record's own name,
// the block number is always 0,
// the count byte is a value in the range 1-32,
// followed by the 1-32 data bytes
//
// Note: When we send the NSEC record in mDNS, the window size is set to 32.
// We need to find out what the last non-NULL byte is. If we are copying out
// from an RDATA, we have the right length. As we need to handle both the case,
// we loop to find the right value instead of blindly using len to copy.
for (i=wlen; i>0; i--) if (nsec[i-1]) break;
ptr = putDomainNameAsLabels(msg, ptr, limit, rr->name);
if (!ptr)
{
goto mdns_nsec_exit;
}
if (i) // Only put a block if at least one type exists for this name
{
if (ptr + 2 + i > limit)
{
ptr = mDNSNULL;
goto mdns_nsec_exit;
}
*ptr++ = 0;
*ptr++ = (mDNSu8)i;
for (j=0; j<i; j++) *ptr++ = nsec[j];
}
mdns_nsec_exit:
if (!ptr)
{
LogRedact(MDNS_LOG_CATEGORY_MDNS, MDNS_LOG_DEBUG,
"The mDNS message does not have enough space for the NSEC record, will add it to the next message (This is not an error message) -- "
"remaining space: %ld, NSEC name: " PRI_DM_NAME, limit - save, DM_NAME_PARAM(rr->name));
}
return ptr;
}
else
{
int win, wlen;
int len = rr->rdlength - dlen;
// Sanity check whether the bitmap is good
while (len)
{
if (len < 3)
{ LogMsg("putRData: invalid length %d", len); return mDNSNULL; }
win = *nsec++;
wlen = *nsec++;
len -= 2;
if (len < wlen || wlen < 1 || wlen > 32)
{ LogMsg("putRData: invalid window length %d", wlen); return mDNSNULL; }
if (win < 0 || win >= 256)
{ LogMsg("putRData: invalid window %d", win); return mDNSNULL; }
nsec += wlen;
len -= wlen;
}
if (ptr + rr->rdlength > limit) { LogMsg("putRData: NSEC rdlength beyond limit %##s (%s), ptr %p, rdlength %d, limit %p", rr->name->c, DNSTypeName(rr->rrtype), ptr, rr->rdlength, limit); return(mDNSNULL);}
// No compression allowed for "nxt", just copy the data.
mDNSPlatformMemCopy(ptr, rdb->data, rr->rdlength);
return(ptr + rr->rdlength);
}
}
default: debugf("putRData: Warning! Writing unknown resource type %d as raw data", rr->rrtype);
if (ptr + rr->rdlength > limit) return(mDNSNULL);
mDNSPlatformMemCopy(ptr, rdb->data, rr->rdlength);
return(ptr + rr->rdlength);
}
}
#define IsUnicastUpdate(X) (!mDNSOpaque16IsZero((X)->h.id) && ((X)->h.flags.b[0] & kDNSFlag0_OP_Mask) == kDNSFlag0_OP_Update)
mDNSexport mDNSu8 *PutResourceRecordTTLWithLimit(DNSMessage *const msg, mDNSu8 *ptr, mDNSu16 *count,
const ResourceRecord *rr, mDNSu32 ttl, const mDNSu8 *limit)
{
mDNSu8 *endofrdata;
mDNSu16 actualLength;
// When sending SRV to conventional DNS server (i.e. in DNS update requests) we should not do name compression on the rdata (RFC 2782)
const DNSMessage *const rdatacompressionbase = (IsUnicastUpdate(msg) && rr->rrtype == kDNSType_SRV) ? mDNSNULL : msg;
if (rr->RecordType == kDNSRecordTypeUnregistered)
{
LogRedact(MDNS_LOG_CATEGORY_DEFAULT, MDNS_LOG_ERROR,
"Attempt to put kDNSRecordTypeUnregistered " PRI_DM_NAME " (" PUB_S ")",
DM_NAME_PARAM(rr->name), DNSTypeName(rr->rrtype));
return(ptr);
}
if (!ptr)
{
LogRedact(MDNS_LOG_CATEGORY_DEFAULT, MDNS_LOG_ERROR,
"Pointer to message is NULL while filling resource record " PRI_DM_NAME " (" PUB_S ")",
DM_NAME_PARAM(rr->name), DNSTypeName(rr->rrtype));
return(mDNSNULL);
}
ptr = putDomainNameAsLabels(msg, ptr, limit, rr->name);
// If we're out-of-space, return mDNSNULL
if (!ptr || ptr + 10 >= limit)
{
LogRedact(MDNS_LOG_CATEGORY_DEFAULT, MDNS_LOG_DEBUG,
"Can't put more names into current message, will possibly put it into the next message - "
"name: " PRI_DM_NAME " (" PUB_S "), remaining space: %ld",
DM_NAME_PARAM(rr->name), DNSTypeName(rr->rrtype), (long)(limit - ptr));
return(mDNSNULL);
}
ptr[0] = (mDNSu8)(rr->rrtype >> 8);
ptr[1] = (mDNSu8)(rr->rrtype & 0xFF);
ptr[2] = (mDNSu8)(rr->rrclass >> 8);
ptr[3] = (mDNSu8)(rr->rrclass & 0xFF);
ptr[4] = (mDNSu8)((ttl >> 24) & 0xFF);
ptr[5] = (mDNSu8)((ttl >> 16) & 0xFF);
ptr[6] = (mDNSu8)((ttl >> 8) & 0xFF);
ptr[7] = (mDNSu8)( ttl & 0xFF);
// ptr[8] and ptr[9] filled in *after* we find out how much space the rdata takes
endofrdata = putRData(rdatacompressionbase, ptr+10, limit, rr);
if (!endofrdata)
{
LogRedact(MDNS_LOG_CATEGORY_DEFAULT, MDNS_LOG_DEBUG,
"Can't put more rdata into current message, will possibly put it into the next message - "
"name: " PRI_DM_NAME " (" PUB_S "), remaining space: %ld",
DM_NAME_PARAM(rr->name), DNSTypeName(rr->rrtype), (long)(limit - ptr - 10));
return(mDNSNULL);
}
// Go back and fill in the actual number of data bytes we wrote
// (actualLength can be less than rdlength when domain name compression is used)
actualLength = (mDNSu16)(endofrdata - ptr - 10);
ptr[8] = (mDNSu8)(actualLength >> 8);
ptr[9] = (mDNSu8)(actualLength & 0xFF);
if (count)
{
(*count)++;
}
else
{
LogRedact(MDNS_LOG_CATEGORY_DEFAULT, MDNS_LOG_ERROR,
"No target count to update for " PRI_DM_NAME " (" PUB_S ")",
DM_NAME_PARAM(rr->name), DNSTypeName(rr->rrtype));
}
return(endofrdata);
}
mDNSlocal mDNSu8 *putEmptyResourceRecord(DNSMessage *const msg, mDNSu8 *ptr, const mDNSu8 *const limit, mDNSu16 *count, const AuthRecord *rr)
{
ptr = putDomainNameAsLabels(msg, ptr, limit, rr->resrec.name);
if (!ptr || ptr + 10 > limit) return(mDNSNULL); // If we're out-of-space, return mDNSNULL
ptr[0] = (mDNSu8)(rr->resrec.rrtype >> 8); // Put type
ptr[1] = (mDNSu8)(rr->resrec.rrtype & 0xFF);
ptr[2] = (mDNSu8)(rr->resrec.rrclass >> 8); // Put class
ptr[3] = (mDNSu8)(rr->resrec.rrclass & 0xFF);
ptr[4] = ptr[5] = ptr[6] = ptr[7] = 0; // TTL is zero
ptr[8] = ptr[9] = 0; // RDATA length is zero
(*count)++;
return(ptr + 10);
}
mDNSexport mDNSu8 *putQuestion(DNSMessage *const msg, mDNSu8 *ptr, const mDNSu8 *const limit, const domainname *const name, mDNSu16 rrtype, mDNSu16 rrclass)
{
ptr = putDomainNameAsLabels(msg, ptr, limit, name);
if (!ptr || ptr+4 >= limit) return(mDNSNULL); // If we're out-of-space, return mDNSNULL
ptr[0] = (mDNSu8)(rrtype >> 8);
ptr[1] = (mDNSu8)(rrtype & 0xFF);
ptr[2] = (mDNSu8)(rrclass >> 8);
ptr[3] = (mDNSu8)(rrclass & 0xFF);
msg->h.numQuestions++;
return(ptr+4);
}
// for dynamic updates
mDNSexport mDNSu8 *putZone(DNSMessage *const msg, mDNSu8 *ptr, mDNSu8 *limit, const domainname *zone, mDNSOpaque16 zoneClass)
{
ptr = putDomainNameAsLabels(msg, ptr, limit, zone);
if (!ptr || ptr + 4 > limit) return mDNSNULL; // If we're out-of-space, return NULL
*ptr++ = (mDNSu8)(kDNSType_SOA >> 8);
*ptr++ = (mDNSu8)(kDNSType_SOA & 0xFF);
*ptr++ = zoneClass.b[0];
*ptr++ = zoneClass.b[1];
msg->h.mDNS_numZones++;
return ptr;
}
// for dynamic updates
mDNSexport mDNSu8 *putPrereqNameNotInUse(const domainname *const name, DNSMessage *const msg, mDNSu8 *const ptr, mDNSu8 *const end)
{
AuthRecord prereq;
mDNS_SetupResourceRecord(&prereq, mDNSNULL, mDNSInterface_Any, kDNSQType_ANY, kStandardTTL, 0, AuthRecordAny, mDNSNULL, mDNSNULL);
AssignDomainName(&prereq.namestorage, name);
prereq.resrec.rrtype = kDNSQType_ANY;
prereq.resrec.rrclass = kDNSClass_NONE;
return putEmptyResourceRecord(msg, ptr, end, &msg->h.mDNS_numPrereqs, &prereq);
}
// for dynamic updates
mDNSexport mDNSu8 *putDeletionRecord(DNSMessage *msg, mDNSu8 *ptr, ResourceRecord *rr)
{
// deletion: specify record w/ TTL 0, class NONE
const mDNSu16 origclass = rr->rrclass;
rr->rrclass = kDNSClass_NONE;
ptr = PutResourceRecordTTLJumbo(msg, ptr, &msg->h.mDNS_numUpdates, rr, 0);
rr->rrclass = origclass;
return ptr;
}
// for dynamic updates
mDNSexport mDNSu8 *putDeletionRecordWithLimit(DNSMessage *msg, mDNSu8 *ptr, ResourceRecord *rr, mDNSu8 *limit)
{
// deletion: specify record w/ TTL 0, class NONE
const mDNSu16 origclass = rr->rrclass;
rr->rrclass = kDNSClass_NONE;
ptr = PutResourceRecordTTLWithLimit(msg, ptr, &msg->h.mDNS_numUpdates, rr, 0, limit);
rr->rrclass = origclass;
return ptr;
}
mDNSexport mDNSu8 *putDeleteRRSetWithLimit(DNSMessage *msg, mDNSu8 *ptr, const domainname *name, mDNSu16 rrtype, mDNSu8 *limit)
{
mDNSu16 class = kDNSQClass_ANY;
ptr = putDomainNameAsLabels(msg, ptr, limit, name);
if (!ptr || ptr + 10 >= limit) return mDNSNULL; // If we're out-of-space, return mDNSNULL
ptr[0] = (mDNSu8)(rrtype >> 8);
ptr[1] = (mDNSu8)(rrtype & 0xFF);
ptr[2] = (mDNSu8)(class >> 8);
ptr[3] = (mDNSu8)(class & 0xFF);
ptr[4] = ptr[5] = ptr[6] = ptr[7] = 0; // zero ttl
ptr[8] = ptr[9] = 0; // zero rdlength/rdata
msg->h.mDNS_numUpdates++;
return ptr + 10;
}
// for dynamic updates
mDNSexport mDNSu8 *putDeleteAllRRSets(DNSMessage *msg, mDNSu8 *ptr, const domainname *name)
{
const mDNSu8 *limit = msg->data + AbsoluteMaxDNSMessageData;
mDNSu16 class = kDNSQClass_ANY;
mDNSu16 rrtype = kDNSQType_ANY;
ptr = putDomainNameAsLabels(msg, ptr, limit, name);
if (!ptr || ptr + 10 >= limit) return mDNSNULL; // If we're out-of-space, return mDNSNULL
ptr[0] = (mDNSu8)(rrtype >> 8);
ptr[1] = (mDNSu8)(rrtype & 0xFF);
ptr[2] = (mDNSu8)(class >> 8);
ptr[3] = (mDNSu8)(class & 0xFF);
ptr[4] = ptr[5] = ptr[6] = ptr[7] = 0; // zero ttl
ptr[8] = ptr[9] = 0; // zero rdlength/rdata
msg->h.mDNS_numUpdates++;
return ptr + 10;
}
// for dynamic updates
mDNSexport mDNSu8 *putUpdateLease(DNSMessage *msg, mDNSu8 *ptr, mDNSu32 lease)
{
AuthRecord rr;
mDNS_SetupResourceRecord(&rr, mDNSNULL, mDNSInterface_Any, kDNSType_OPT, kStandardTTL, kDNSRecordTypeKnownUnique, AuthRecordAny, mDNSNULL, mDNSNULL);
rr.resrec.rrclass = NormalMaxDNSMessageData;
rr.resrec.rdlength = sizeof(rdataOPT); // One option in this OPT record
rr.resrec.rdestimate = sizeof(rdataOPT);
rr.resrec.rdata->u.opt[0].opt = kDNSOpt_Lease;
rr.resrec.rdata->u.opt[0].u.updatelease = lease;
ptr = PutResourceRecordTTLJumbo(msg, ptr, &msg->h.numAdditionals, &rr.resrec, 0);
if (!ptr) { LogMsg("ERROR: putUpdateLease - PutResourceRecordTTL"); return mDNSNULL; }
return ptr;
}
// for dynamic updates
mDNSexport mDNSu8 *putUpdateLeaseWithLimit(DNSMessage *msg, mDNSu8 *ptr, mDNSu32 lease, mDNSu8 *limit)
{
AuthRecord rr;
mDNS_SetupResourceRecord(&rr, mDNSNULL, mDNSInterface_Any, kDNSType_OPT, kStandardTTL, kDNSRecordTypeKnownUnique, AuthRecordAny, mDNSNULL, mDNSNULL);
rr.resrec.rrclass = NormalMaxDNSMessageData;
rr.resrec.rdlength = sizeof(rdataOPT); // One option in this OPT record
rr.resrec.rdestimate = sizeof(rdataOPT);
rr.resrec.rdata->u.opt[0].opt = kDNSOpt_Lease;
rr.resrec.rdata->u.opt[0].u.updatelease = lease;
ptr = PutResourceRecordTTLWithLimit(msg, ptr, &msg->h.numAdditionals, &rr.resrec, 0, limit);
if (!ptr) { LogMsg("ERROR: putUpdateLeaseWithLimit - PutResourceRecordTTLWithLimit"); return mDNSNULL; }
return ptr;
}
// ***************************************************************************
// MARK: - DNS Message Parsing Functions
mDNSexport mDNSu32 DomainNameHashValue(const domainname *const name)
{
mDNSu32 sum = 0;
const mDNSu8 *c;
for (c = name->c; c[0] != 0 && c[1] != 0; c += 2)
{
sum += ((mDNSIsUpperCase(c[0]) ? c[0] + 'a' - 'A' : c[0]) << 8) |
(mDNSIsUpperCase(c[1]) ? c[1] + 'a' - 'A' : c[1]);
sum = (sum<<3) | (sum>>29);
}
if (c[0]) sum += ((mDNSIsUpperCase(c[0]) ? c[0] + 'a' - 'A' : c[0]) << 8);
return(sum);
}
mDNSexport void SetNewRData(ResourceRecord *const rr, RData *NewRData, mDNSu16 rdlength)
{
if (NewRData)
{
rr->rdata = NewRData;
rr->rdlength = rdlength;
}
rr->rdlength = GetRDLength(rr, mDNSfalse);
rr->rdestimate = GetRDLength(rr, mDNStrue);
rr->rdatahash = RDataHashValue(rr);
}
mDNSexport const mDNSu8 *skipDomainName(const DNSMessage *const msg, const mDNSu8 *ptr, const mDNSu8 *const end)
{
mDNSu16 total = 0;
if (ptr < (const mDNSu8*)msg || ptr >= end)
{ debugf("skipDomainName: Illegal ptr not within packet boundaries"); return(mDNSNULL); }
while (1) // Read sequence of labels
{
const mDNSu8 len = *ptr++; // Read length of this label
if (len == 0) return(ptr); // If length is zero, that means this name is complete
switch (len & 0xC0)
{
case 0x00: if (ptr + len >= end) // Remember: expect at least one more byte for the root label
{ debugf("skipDomainName: Malformed domain name (overruns packet end)"); return(mDNSNULL); }
if (total + 1 + len >= MAX_DOMAIN_NAME) // Remember: expect at least one more byte for the root label
{ debugf("skipDomainName: Malformed domain name (more than 256 characters)"); return(mDNSNULL); }
ptr += len;
total += 1 + len;
break;
case 0x40: debugf("skipDomainName: Extended EDNS0 label types 0x%X not supported", len); return(mDNSNULL);
case 0x80: debugf("skipDomainName: Illegal label length 0x%X", len); return(mDNSNULL);
case 0xC0: if (ptr + 1 > end) // Skip the two-byte name compression pointer.
{ debugf("skipDomainName: Malformed compression pointer (overruns packet end)"); return(mDNSNULL); }
return(ptr + 1);
default:
break;
}
}
}
// Routine to fetch an FQDN from the DNS message, following compression pointers if necessary.
mDNSexport const mDNSu8 *getDomainName(const DNSMessage *const msg, const mDNSu8 *ptr, const mDNSu8 *const end,
domainname *const name)
{
const mDNSu8 *nextbyte = mDNSNULL; // Record where we got to before we started following pointers
mDNSu8 *np = name->c; // Name pointer
const mDNSu8 *const limit = np + MAX_DOMAIN_NAME; // Limit so we don't overrun buffer
if (ptr < (const mDNSu8*)msg || ptr >= end)
{ debugf("getDomainName: Illegal ptr not within packet boundaries"); return(mDNSNULL); }
*np = 0; // Tentatively place the root label here (may be overwritten if we have more labels)
while (1) // Read sequence of labels
{
int i;
mDNSu16 offset;
const mDNSu8 len = *ptr++; // Read length of this label
if (len == 0) break; // If length is zero, that means this name is complete
switch (len & 0xC0)
{
case 0x00: if (ptr + len >= end) // Remember: expect at least one more byte for the root label
{ debugf("getDomainName: Malformed domain name (overruns packet end)"); return(mDNSNULL); }
if (np + 1 + len >= limit) // Remember: expect at least one more byte for the root label
{ debugf("getDomainName: Malformed domain name (more than 256 characters)"); return(mDNSNULL); }
*np++ = len;
for (i=0; i<len; i++) *np++ = *ptr++;
*np = 0; // Tentatively place the root label here (may be overwritten if we have more labels)
break;
case 0x40: debugf("getDomainName: Extended EDNS0 label types 0x%X not supported in name %##s", len, name->c);
return(mDNSNULL);
case 0x80: debugf("getDomainName: Illegal label length 0x%X in domain name %##s", len, name->c); return(mDNSNULL);
case 0xC0: if (ptr >= end)
{ debugf("getDomainName: Malformed compression label (overruns packet end)"); return(mDNSNULL); }
offset = (mDNSu16)((((mDNSu16)(len & 0x3F)) << 8) | *ptr++);
if (!nextbyte) nextbyte = ptr; // Record where we got to before we started following pointers
ptr = (const mDNSu8 *)msg + offset;
if (ptr < (const mDNSu8*)msg || ptr >= end)
{ debugf("getDomainName: Illegal compression pointer not within packet boundaries"); return(mDNSNULL); }
if (*ptr & 0xC0)
{ debugf("getDomainName: Compression pointer must point to real label"); return(mDNSNULL); }
break;
default:
break;
}
}
if (nextbyte) return(nextbyte);
else return(ptr);
}
mDNSexport const mDNSu8 *skipResourceRecord(const DNSMessage *msg, const mDNSu8 *ptr, const mDNSu8 *end)
{
mDNSu16 pktrdlength;
ptr = skipDomainName(msg, ptr, end);
if (!ptr) { debugf("skipResourceRecord: Malformed RR name"); return(mDNSNULL); }
if (ptr + 10 > end) { debugf("skipResourceRecord: Malformed RR -- no type/class/ttl/len!"); return(mDNSNULL); }
pktrdlength = (mDNSu16)((mDNSu16)ptr[8] << 8 | ptr[9]);
ptr += 10;
if (ptr + pktrdlength > end) { debugf("skipResourceRecord: RDATA exceeds end of packet"); return(mDNSNULL); }
return(ptr + pktrdlength);
}
// Sanity check whether the NSEC/NSEC3 bitmap is good
mDNSlocal const mDNSu8 *SanityCheckBitMap(const mDNSu8 *bmap, const mDNSu8 *end, int len)
{
int win, wlen;
while (bmap < end)
{
if (len < 3)
{
LogInfo("SanityCheckBitMap: invalid length %d", len);
return mDNSNULL;
}
win = *bmap++;
wlen = *bmap++;
len -= 2;
if (len < wlen || wlen < 1 || wlen > 32)
{
LogInfo("SanityCheckBitMap: invalid window length %d", wlen);
return mDNSNULL;
}
if (win < 0 || win >= 256)
{
LogInfo("SanityCheckBitMap: invalid window %d", win);
return mDNSNULL;
}
bmap += wlen;
len -= wlen;
}
return (const mDNSu8 *)bmap;
}
mDNSlocal mDNSBool AssignDomainNameWithLimit(domainname *const dst, const domainname *src, const mDNSu8 *const end)
{
const mDNSu32 len = DomainNameLengthLimit(src, end);
if ((len >= 1) && (len <= MAX_DOMAIN_NAME))
{
mDNSPlatformMemCopy(dst->c, src->c, len);
return mDNStrue;
}
else
{
dst->c[0] = 0;
return mDNSfalse;
}
}
// This function is called with "msg" when we receive a DNS message and needs to parse a single resource record
// pointed to by "ptr". Some resource records like SOA, SRV are converted to host order and also expanded
// (domainnames are expanded to 256 bytes) when stored in memory.
//
// This function can also be called with "NULL" msg to parse a single resource record pointed to by ptr.
// The caller can do this only if the names in the resource records are not compressed and validity of the
// resource record has already been done before.
mDNSexport mDNSBool SetRData(const DNSMessage *const msg, const mDNSu8 *ptr, const mDNSu8 *end, ResourceRecord *const rr,
const mDNSu16 rdlength)
{
RDataBody2 *const rdb = (RDataBody2 *)&rr->rdata->u;
switch (rr->rrtype)
{
case kDNSType_A:
if (rdlength != sizeof(mDNSv4Addr))
goto fail;
rdb->ipv4.b[0] = ptr[0];
rdb->ipv4.b[1] = ptr[1];
rdb->ipv4.b[2] = ptr[2];
rdb->ipv4.b[3] = ptr[3];
break;
case kDNSType_NS:
case kDNSType_MD:
case kDNSType_MF:
case kDNSType_CNAME:
case kDNSType_MB:
case kDNSType_MG:
case kDNSType_MR:
case kDNSType_PTR:
case kDNSType_NSAP_PTR:
case kDNSType_DNAME:
if (msg)
{
ptr = getDomainName(msg, ptr, end, &rdb->name);
}
else
{
if (!AssignDomainNameWithLimit(&rdb->name, (const domainname *)ptr, end))
{
goto fail;
}
ptr += DomainNameLength(&rdb->name);
}
if (ptr != end)
{
debugf("SetRData: Malformed CNAME/PTR RDATA name");
goto fail;
}
break;
case kDNSType_SOA:
if (msg)
{
ptr = getDomainName(msg, ptr, end, &rdb->soa.mname);
}
else
{
if (!AssignDomainNameWithLimit(&rdb->soa.mname, (const domainname *)ptr, end))
{
goto fail;
}
ptr += DomainNameLength(&rdb->soa.mname);
}
if (!ptr)
{
debugf("SetRData: Malformed SOA RDATA mname");
goto fail;
}
if (msg)
{
ptr = getDomainName(msg, ptr, end, &rdb->soa.rname);
}
else
{
if (!AssignDomainNameWithLimit(&rdb->soa.rname, (const domainname *)ptr, end))
{
goto fail;
}
ptr += DomainNameLength(&rdb->soa.rname);
}
if (!ptr)
{
debugf("SetRData: Malformed SOA RDATA rname");
goto fail;
}
if (ptr + 0x14 != end)
{
debugf("SetRData: Malformed SOA RDATA");
goto fail;
}
rdb->soa.serial = (mDNSs32) ((mDNSs32)ptr[0x00] << 24 | (mDNSs32)ptr[0x01] << 16 | (mDNSs32)ptr[0x02] << 8 | ptr[0x03]);
rdb->soa.refresh = (mDNSu32) ((mDNSu32)ptr[0x04] << 24 | (mDNSu32)ptr[0x05] << 16 | (mDNSu32)ptr[0x06] << 8 | ptr[0x07]);
rdb->soa.retry = (mDNSu32) ((mDNSu32)ptr[0x08] << 24 | (mDNSu32)ptr[0x09] << 16 | (mDNSu32)ptr[0x0A] << 8 | ptr[0x0B]);
rdb->soa.expire = (mDNSu32) ((mDNSu32)ptr[0x0C] << 24 | (mDNSu32)ptr[0x0D] << 16 | (mDNSu32)ptr[0x0E] << 8 | ptr[0x0F]);
rdb->soa.min = (mDNSu32) ((mDNSu32)ptr[0x10] << 24 | (mDNSu32)ptr[0x11] << 16 | (mDNSu32)ptr[0x12] << 8 | ptr[0x13]);
break;
case kDNSType_HINFO:
// See https://tools.ietf.org/html/rfc1035#section-3.3.2 for HINFO RDATA format.
{
// HINFO should contain RDATA.
if (end <= ptr || rdlength != (mDNSu32)(end - ptr))
{
LogRedact(MDNS_LOG_CATEGORY_DEFAULT, MDNS_LOG_DEBUG,
"SetRData: Malformed HINFO RDATA - invalid RDATA length: %u", rdlength);
goto fail;
}
const mDNSu8 *currentPtr = ptr;
// CPU character string length should be less than the RDATA length.
mDNSu32 cpuCharacterStrLength = currentPtr[0];
if (1 + cpuCharacterStrLength >= (mDNSu32)(end - currentPtr))
{
LogRedact(MDNS_LOG_CATEGORY_DEFAULT, MDNS_LOG_DEBUG,
"SetRData: Malformed HINFO RDATA - CPU character string goes out of boundary");
goto fail;
}
currentPtr += 1 + cpuCharacterStrLength;
// OS character string should end at the RDATA ending.
mDNSu32 osCharacterStrLength = currentPtr[0];
if (1 + osCharacterStrLength != (mDNSu32)(end - currentPtr))
{
LogRedact(MDNS_LOG_CATEGORY_DEFAULT, MDNS_LOG_DEBUG,
"SetRData: Malformed HINFO RDATA - OS character string does not end at the RDATA ending");
goto fail;
}
// Copy the validated RDATA.
rr->rdlength = rdlength;
mDNSPlatformMemCopy(rdb->data, ptr, rdlength);
break;
}
case kDNSType_NULL:
case kDNSType_TXT:
case kDNSType_X25:
case kDNSType_ISDN:
case kDNSType_LOC:
case kDNSType_DHCID:
case kDNSType_SVCB:
case kDNSType_HTTPS:
rr->rdlength = rdlength;
mDNSPlatformMemCopy(rdb->data, ptr, rdlength);
break;
case kDNSType_MX:
case kDNSType_AFSDB:
case kDNSType_RT:
case kDNSType_KX:
// Preference + domainname
if (rdlength < 3)
goto fail;
rdb->mx.preference = (mDNSu16)((mDNSu16)ptr[0] << 8 | ptr[1]);
ptr += 2;
if (msg)
{
ptr = getDomainName(msg, ptr, end, &rdb->mx.exchange);
}
else
{
if (!AssignDomainNameWithLimit(&rdb->mx.exchange, (const domainname *)ptr, end))
{
goto fail;
}
ptr += DomainNameLength(&rdb->mx.exchange);
}
if (ptr != end)
{
debugf("SetRData: Malformed MX name");
goto fail;
}
break;
case kDNSType_MINFO:
case kDNSType_RP:
// Domainname + domainname
if (msg)
{
ptr = getDomainName(msg, ptr, end, &rdb->rp.mbox);
}
else
{
if (!AssignDomainNameWithLimit(&rdb->rp.mbox, (const domainname *)ptr, end))
{
goto fail;
}
ptr += DomainNameLength(&rdb->rp.mbox);
}
if (!ptr)
{
debugf("SetRData: Malformed RP mbox");
goto fail;
}
if (msg)
{
ptr = getDomainName(msg, ptr, end, &rdb->rp.txt);
}
else
{
if (!AssignDomainNameWithLimit(&rdb->rp.txt, (const domainname *)ptr, end))
{
goto fail;
}
ptr += DomainNameLength(&rdb->rp.txt);
}
if (ptr != end)
{
debugf("SetRData: Malformed RP txt");
goto fail;
}
break;
case kDNSType_PX:
// Preference + domainname + domainname
if (rdlength < 4)
goto fail;
rdb->px.preference = (mDNSu16)((mDNSu16)ptr[0] << 8 | ptr[1]);
ptr += 2;
if (msg)
{
ptr = getDomainName(msg, ptr, end, &rdb->px.map822);
}
else
{
if (!AssignDomainNameWithLimit(&rdb->px.map822, (const domainname *)ptr, end))
{
goto fail;
}
ptr += DomainNameLength(&rdb->px.map822);
}
if (!ptr)
{
debugf("SetRData: Malformed PX map822");
goto fail;
}
if (msg)
{
ptr = getDomainName(msg, ptr, end, &rdb->px.mapx400);
}
else
{
if (!AssignDomainNameWithLimit(&rdb->px.mapx400, (const domainname *)ptr, end))
{
goto fail;
}
ptr += DomainNameLength(&rdb->px.mapx400);
}
if (ptr != end)
{
debugf("SetRData: Malformed PX mapx400");
goto fail;
}
break;
case kDNSType_AAAA:
if (rdlength != sizeof(mDNSv6Addr))
goto fail;
mDNSPlatformMemCopy(&rdb->ipv6, ptr, sizeof(rdb->ipv6));
break;
case kDNSType_SRV:
// Priority + weight + port + domainname
if (rdlength < 7)
goto fail;
rdb->srv.priority = (mDNSu16)((mDNSu16)ptr[0] << 8 | ptr[1]);
rdb->srv.weight = (mDNSu16)((mDNSu16)ptr[2] << 8 | ptr[3]);
rdb->srv.port.b[0] = ptr[4];
rdb->srv.port.b[1] = ptr[5];
ptr += 6;
if (msg)
{
ptr = getDomainName(msg, ptr, end, &rdb->srv.target);
}
else
{
if (!AssignDomainNameWithLimit(&rdb->srv.target, (const domainname *)ptr, end))
{
goto fail;
}
ptr += DomainNameLength(&rdb->srv.target);
}
if (ptr != end)
{
debugf("SetRData: Malformed SRV RDATA name");
goto fail;
}
break;
case kDNSType_NAPTR:
{
int savelen, len;
domainname name;
mDNSu32 namelen;
const mDNSu8 *orig = ptr;
// Make sure the data is parseable and within the limits.
//
// Fixed length: Order, preference (4 bytes)
// Variable length: flags, service, regexp, domainname
if (rdlength < 8)
goto fail;
// Order, preference.
ptr += 4;
// Parse flags, Service and Regexp
// length in the first byte does not include the length byte itself
len = *ptr + 1;
ptr += len;
if (ptr >= end)
{
LogInfo("SetRData: Malformed NAPTR flags");
goto fail;
}
// Service
len = *ptr + 1;
ptr += len;
if (ptr >= end)
{
LogInfo("SetRData: Malformed NAPTR service");
goto fail;
}
// Regexp
len = *ptr + 1;
ptr += len;
if (ptr >= end)
{
LogInfo("SetRData: Malformed NAPTR regexp");
goto fail;
}
savelen = (int)(ptr - orig);
// RFC 2915 states that name compression is not allowed for this field. But RFC 3597
// states that for NAPTR we should decompress. We make sure that we store the full
// name rather than the compressed name
if (msg)
{
ptr = getDomainName(msg, ptr, end, &name);
namelen = DomainNameLength(&name);
}
else
{
if (!AssignDomainNameWithLimit(&name, (const domainname *)ptr, end))
{
goto fail;
}
namelen = DomainNameLength(&name);
ptr += namelen;
}
if (ptr != end)
{
LogInfo("SetRData: Malformed NAPTR RDATA name");
goto fail;
}
rr->rdlength = savelen + namelen;
// The uncompressed size should not exceed the limits
if (rr->rdlength > MaximumRDSize)
{
LogInfo("SetRData: Malformed NAPTR rdlength %d, rr->rdlength %d, "
"bmaplen %d, name %##s", rdlength, rr->rdlength, name.c);
goto fail;
}
mDNSPlatformMemCopy(rdb->data, orig, savelen);
mDNSPlatformMemCopy(rdb->data + savelen, name.c, namelen);
break;
}
case kDNSType_OPT: {
const mDNSu8 * const dataend = &rr->rdata->u.data[rr->rdata->MaxRDLength];
rdataOPT *opt = rr->rdata->u.opt;
rr->rdlength = 0;
while ((ptr < end) && ((dataend - ((const mDNSu8 *)opt)) >= ((mDNSs32)sizeof(*opt))))
{
const rdataOPT *const currentopt = opt;
if (ptr + 4 > end) { LogInfo("SetRData: OPT RDATA ptr + 4 > end"); goto fail; }
opt->opt = (mDNSu16)((mDNSu16)ptr[0] << 8 | ptr[1]);
opt->optlen = (mDNSu16)((mDNSu16)ptr[2] << 8 | ptr[3]);
ptr += 4;
if (ptr + opt->optlen > end) { LogInfo("SetRData: ptr + opt->optlen > end"); goto fail; }
switch (opt->opt)
{
case kDNSOpt_LLQ:
if (opt->optlen == DNSOpt_LLQData_Space - 4)
{
opt->u.llq.vers = (mDNSu16)((mDNSu16)ptr[0] << 8 | ptr[1]);
opt->u.llq.llqOp = (mDNSu16)((mDNSu16)ptr[2] << 8 | ptr[3]);
opt->u.llq.err = (mDNSu16)((mDNSu16)ptr[4] << 8 | ptr[5]);
mDNSPlatformMemCopy(opt->u.llq.id.b, ptr+6, 8);
opt->u.llq.llqlease = (mDNSu32) ((mDNSu32)ptr[14] << 24 | (mDNSu32)ptr[15] << 16 | (mDNSu32)ptr[16] << 8 | ptr[17]);
if (opt->u.llq.llqlease > 0x70000000UL / mDNSPlatformOneSecond)
opt->u.llq.llqlease = 0x70000000UL / mDNSPlatformOneSecond;
opt++;
}
break;
case kDNSOpt_Lease:
if (opt->optlen == DNSOpt_LeaseData_Space - 4)
{
opt->u.updatelease = (mDNSu32) ((mDNSu32)ptr[0] << 24 | (mDNSu32)ptr[1] << 16 | (mDNSu32)ptr[2] << 8 | ptr[3]);
if (opt->u.updatelease > 0x70000000UL / mDNSPlatformOneSecond)
opt->u.updatelease = 0x70000000UL / mDNSPlatformOneSecond;
opt++;
}
break;
case kDNSOpt_Owner:
if (ValidOwnerLength(opt->optlen))
{
opt->u.owner.vers = ptr[0];
opt->u.owner.seq = ptr[1];
mDNSPlatformMemCopy(opt->u.owner.HMAC.b, ptr+2, 6); // 6-byte MAC address
mDNSPlatformMemCopy(opt->u.owner.IMAC.b, ptr+2, 6); // 6-byte MAC address
opt->u.owner.password = zeroEthAddr;
if (opt->optlen >= DNSOpt_OwnerData_ID_Wake_Space-4)
{
mDNSPlatformMemCopy(opt->u.owner.IMAC.b, ptr+8, 6); // 6-byte MAC address
// This mDNSPlatformMemCopy is safe because the ValidOwnerLength(opt->optlen) check above
// ensures that opt->optlen is no more than DNSOpt_OwnerData_ID_Wake_PW6_Space - 4
if (opt->optlen > DNSOpt_OwnerData_ID_Wake_Space-4)
mDNSPlatformMemCopy(opt->u.owner.password.b, ptr+14, opt->optlen - (DNSOpt_OwnerData_ID_Wake_Space-4));
}
opt++;
}
break;
case kDNSOpt_Trace:
if (opt->optlen == DNSOpt_TraceData_Space - 4)
{
opt->u.tracer.platf = ptr[0];
opt->u.tracer.mDNSv = (mDNSu32) ((mDNSu32)ptr[1] << 24 | (mDNSu32)ptr[2] << 16 | (mDNSu32)ptr[3] << 8 | ptr[4]);
opt++;
}
else
{
opt->u.tracer.platf = 0xFF;
opt->u.tracer.mDNSv = 0xFFFFFFFF;
opt++;
}
break;
case kDNSOpt_TSR:
if (opt->optlen == DNSOpt_TSRData_Space - 4)
{
opt->u.tsr.timeStamp = (mDNSs32) ((mDNSu32)ptr[0] << 24 | (mDNSu32)ptr[1] << 16 | (mDNSu32)ptr[2] << 8 | ptr[3]);
opt->u.tsr.hostkeyHash = (mDNSu32) ((mDNSu32)ptr[4] << 24 | (mDNSu32)ptr[5] << 16 | (mDNSu32)ptr[6] << 8 | ptr[7]);
opt->u.tsr.recIndex = (mDNSu16) ((mDNSu16)ptr[8] << 8 | ptr[9]);
opt++;
}
break;
default:
break;
}
ptr += currentopt->optlen;
}
rr->rdlength = (mDNSu16)((mDNSu8*)opt - rr->rdata->u.data);
if (ptr != end) { LogInfo("SetRData: Malformed OptRdata"); goto fail; }
break;
}
case kDNSType_NSEC: {
domainname name;
int len = rdlength;
int bmaplen, dlen;
const mDNSu8 *orig = ptr;
const mDNSu8 *bmap;
if (msg)
{
ptr = getDomainName(msg, ptr, end, &name);
}
else
{
if (!AssignDomainNameWithLimit(&name, (const domainname *)ptr, end))
{
goto fail;
}
ptr += DomainNameLength(&name);
}
if (!ptr)
{
LogInfo("SetRData: Malformed NSEC nextname");
goto fail;
}
dlen = DomainNameLength(&name);
// Multicast NSECs use name compression for this field unlike the unicast case which
// does not use compression. And multicast case always succeeds in compression. So,
// the rdlength includes only the compressed space in that case. So, can't
// use the DomainNameLength of name to reduce the length here.
len -= (ptr - orig);
bmaplen = len; // Save the length of the bitmap
bmap = ptr;
ptr = SanityCheckBitMap(bmap, end, len);
if (!ptr)
goto fail;
if (ptr != end)
{
LogInfo("SetRData: Malformed NSEC length not right");
goto fail;
}
// Initialize the right length here. When we call SetNewRData below which in turn calls
// GetRDLength and for NSEC case, it assumes that rdlength is intitialized
rr->rdlength = DomainNameLength(&name) + bmaplen;
// Do we have space after the name expansion ?
if (rr->rdlength > MaximumRDSize)
{
LogInfo("SetRData: Malformed NSEC rdlength %d, rr->rdlength %d, "
"bmaplen %d, name %##s", rdlength, rr->rdlength, name.c);
goto fail;
}
AssignDomainName(&rdb->name, &name);
mDNSPlatformMemCopy(rdb->data + dlen, bmap, bmaplen);
break;
}
case kDNSType_TKEY:
case kDNSType_TSIG:
{
domainname name;
int dlen, rlen;
// The name should not be compressed. But we take the conservative approach
// and uncompress the name before we store it.
if (msg)
{
ptr = getDomainName(msg, ptr, end, &name);
}
else
{
if (!AssignDomainNameWithLimit(&name, (const domainname *)ptr, end))
{
goto fail;
}
ptr += DomainNameLength(&name);
}
if (!ptr || ptr >= end)
{
LogInfo("SetRData: Malformed name for TSIG/TKEY type %d", rr->rrtype);
goto fail;
}
dlen = DomainNameLength(&name);
rlen = (int)(end - ptr);
rr->rdlength = dlen + rlen;
if (rr->rdlength > MaximumRDSize)
{
LogInfo("SetRData: Malformed TSIG/TKEY rdlength %d, rr->rdlength %d, "
"bmaplen %d, name %##s", rdlength, rr->rdlength, name.c);
goto fail;
}
AssignDomainName(&rdb->name, &name);
mDNSPlatformMemCopy(rdb->data + dlen, ptr, rlen);
break;
}
case kDNSType_TSR:
{
rdb->tsr_value = (mDNSs32) ((mDNSu32)ptr[0] << 24 | (mDNSu32)ptr[1] << 16 | (mDNSu32)ptr[2] << 8 | ptr[3]);
break;
}
default:
debugf("SetRData: Warning! Reading resource type %d (%s) as opaque data",
rr->rrtype, DNSTypeName(rr->rrtype));
// Note: Just because we don't understand the record type, that doesn't
// mean we fail. The DNS protocol specifies rdlength, so we can
// safely skip over unknown records and ignore them.
// We also grab a binary copy of the rdata anyway, since the caller
// might know how to interpret it even if we don't.
rr->rdlength = rdlength;
mDNSPlatformMemCopy(rdb->data, ptr, rdlength);
break;
}
return mDNStrue;
fail:
return mDNSfalse;
}
mDNSexport const mDNSu8 *GetLargeResourceRecord(mDNS *const m, const DNSMessage *const msg, const mDNSu8 *ptr,
const mDNSu8 *end, const mDNSInterfaceID InterfaceID, mDNSu8 RecordType, LargeCacheRecord *const largecr)
{
CacheRecord *const rr = &largecr->r;
mDNSu16 pktrdlength;
mDNSu32 maxttl = (!InterfaceID) ? mDNSMaximumUnicastTTLSeconds : mDNSMaximumMulticastTTLSeconds;
if (largecr == &m->rec && m->rec.r.resrec.RecordType)
LogFatalError("GetLargeResourceRecord: m->rec appears to be already in use for %s", CRDisplayString(m, &m->rec.r));
rr->next = mDNSNULL;
rr->resrec.name = &largecr->namestorage;
rr->NextInKAList = mDNSNULL;
rr->TimeRcvd = m ? m->timenow : 0;
rr->DelayDelivery = 0;
rr->NextRequiredQuery = m ? m->timenow : 0; // Will be updated to the real value when we call SetNextCacheCheckTimeForRecord()
#if MDNSRESPONDER_SUPPORTS(APPLE, CACHE_ANALYTICS)
rr->LastCachedAnswerTime = 0;
#endif
rr->CRActiveQuestion = mDNSNULL;
rr->UnansweredQueries = 0;
rr->LastUnansweredTime= 0;
rr->NextInCFList = mDNSNULL;
rr->resrec.InterfaceID = InterfaceID;
#if MDNSRESPONDER_SUPPORTS(APPLE, QUERIER)
mdns_forget(&rr->resrec.metadata);
#else
rr->resrec.rDNSServer = mDNSNULL;
#endif
ptr = getDomainName(msg, ptr, end, &largecr->namestorage); // Will bail out correctly if ptr is NULL
if (!ptr) { debugf("GetLargeResourceRecord: Malformed RR name"); return(mDNSNULL); }
rr->resrec.namehash = DomainNameHashValue(rr->resrec.name);
if (ptr + 10 > end) { debugf("GetLargeResourceRecord: Malformed RR -- no type/class/ttl/len!"); return(mDNSNULL); }
rr->resrec.rrtype = (mDNSu16) ((mDNSu16)ptr[0] << 8 | ptr[1]);
rr->resrec.rrclass = (mDNSu16)(((mDNSu16)ptr[2] << 8 | ptr[3]) & kDNSClass_Mask);
rr->resrec.rroriginalttl = (mDNSu32) ((mDNSu32)ptr[4] << 24 | (mDNSu32)ptr[5] << 16 | (mDNSu32)ptr[6] << 8 | ptr[7]);
if (rr->resrec.rroriginalttl > maxttl && (mDNSs32)rr->resrec.rroriginalttl != -1)
rr->resrec.rroriginalttl = maxttl;
// Note: We don't have to adjust m->NextCacheCheck here -- this is just getting a record into memory for
// us to look at. If we decide to copy it into the cache, then we'll update m->NextCacheCheck accordingly.
pktrdlength = (mDNSu16)((mDNSu16)ptr[8] << 8 | ptr[9]);
// If mDNS record has cache-flush bit set, we mark it unique
// For uDNS records, all are implicitly deemed unique (a single DNS server is always authoritative for the entire RRSet)
if (ptr[2] & (kDNSClass_UniqueRRSet >> 8) || !InterfaceID)
RecordType |= kDNSRecordTypePacketUniqueMask;
ptr += 10;
if (ptr + pktrdlength > end) { debugf("GetLargeResourceRecord: RDATA exceeds end of packet"); return(mDNSNULL); }
end = ptr + pktrdlength; // Adjust end to indicate the end of the rdata for this resource record
rr->resrec.rdata = (RData*)&rr->smallrdatastorage;
rr->resrec.rdata->MaxRDLength = MaximumRDSize;
if (pktrdlength > MaximumRDSize)
{
LogInfo("GetLargeResourceRecord: %s rdata size (%d) exceeds storage (%d)",
DNSTypeName(rr->resrec.rrtype), pktrdlength, rr->resrec.rdata->MaxRDLength);
goto fail;
}
if (!RecordType) LogMsg("GetLargeResourceRecord: No RecordType for %##s", rr->resrec.name->c);
// IMPORTANT: Any record type we understand and unpack into a structure containing domainnames needs to have corresponding
// cases in SameRDataBody() and RDataHashValue() to do a semantic comparison (or checksum) of the structure instead of a blind
// bitwise memory compare (or sum). This is because a domainname is a fixed size structure holding variable-length data.
// Any bytes past the logical end of the name are undefined, and a blind bitwise memory compare may indicate that
// two domainnames are different when semantically they are the same name and it's only the unused bytes that differ.
if (rr->resrec.rrclass == kDNSQClass_ANY && pktrdlength == 0) // Used in update packets to mean "Delete An RRset" (RFC 2136)
rr->resrec.rdlength = 0;
else if (!SetRData(msg, ptr, end, &rr->resrec, pktrdlength))
{
LogRedact(MDNS_LOG_CATEGORY_DEFAULT, MDNS_LOG_ERROR,
"GetLargeResourceRecord: SetRData failed for " PRI_DM_NAME " (" PUB_S ")",
DM_NAME_PARAM(rr->resrec.name), DNSTypeName(rr->resrec.rrtype));
goto fail;
}
SetNewRData(&rr->resrec, mDNSNULL, 0); // Sets rdlength, rdestimate, rdatahash for us
// Success! Now fill in RecordType to show this record contains valid data
rr->resrec.RecordType = RecordType;
return(end);
fail:
// If we were unable to parse the rdata in this record, we indicate that by
// returing a 'kDNSRecordTypePacketNegative' record with rdlength set to zero
rr->resrec.RecordType = kDNSRecordTypePacketNegative;
rr->resrec.rdlength = 0;
rr->resrec.rdestimate = 0;
rr->resrec.rdatahash = 0;
return(end);
}
mDNSexport const mDNSu8 *skipQuestion(const DNSMessage *msg, const mDNSu8 *ptr, const mDNSu8 *end)
{
ptr = skipDomainName(msg, ptr, end);
if (!ptr) { debugf("skipQuestion: Malformed domain name in DNS question section"); return(mDNSNULL); }
if (ptr+4 > end) { debugf("skipQuestion: Malformed DNS question section -- no query type and class!"); return(mDNSNULL); }
return(ptr+4);
}
mDNSexport const mDNSu8 *getQuestion(const DNSMessage *msg, const mDNSu8 *ptr, const mDNSu8 *end, const mDNSInterfaceID InterfaceID,
DNSQuestion *question)
{
mDNSPlatformMemZero(question, sizeof(*question));
question->InterfaceID = InterfaceID;
if (!InterfaceID) question->TargetQID = onesID; // In DNSQuestions we use TargetQID as the indicator of whether it's unicast or multicast
ptr = getDomainName(msg, ptr, end, &question->qname);
if (!ptr) { debugf("Malformed domain name in DNS question section"); return(mDNSNULL); }
if (ptr+4 > end) { debugf("Malformed DNS question section -- no query type and class!"); return(mDNSNULL); }
question->qnamehash = DomainNameHashValue(&question->qname);
question->qtype = (mDNSu16)((mDNSu16)ptr[0] << 8 | ptr[1]); // Get type
question->qclass = (mDNSu16)((mDNSu16)ptr[2] << 8 | ptr[3]); // and class
return(ptr+4);
}
mDNSexport const mDNSu8 *LocateAnswers(const DNSMessage *const msg, const mDNSu8 *const end)
{
int i;
const mDNSu8 *ptr = msg->data;
for (i = 0; i < msg->h.numQuestions && ptr; i++) ptr = skipQuestion(msg, ptr, end);
return(ptr);
}
mDNSexport const mDNSu8 *LocateAuthorities(const DNSMessage *const msg, const mDNSu8 *const end)
{
int i;
const mDNSu8 *ptr = LocateAnswers(msg, end);
for (i = 0; i < msg->h.numAnswers && ptr; i++) ptr = skipResourceRecord(msg, ptr, end);
return(ptr);
}
mDNSexport const mDNSu8 *LocateAdditionals(const DNSMessage *const msg, const mDNSu8 *const end)
{
int i;
const mDNSu8 *ptr = LocateAuthorities(msg, end);
for (i = 0; i < msg->h.numAuthorities; i++) ptr = skipResourceRecord(msg, ptr, end);
return (ptr);
}
mDNSexport const mDNSu8 *LocateOptRR(const DNSMessage *const msg, const mDNSu8 *const end, int minsize)
{
int i;
const mDNSu8 *ptr = LocateAdditionals(msg, end);
// Locate the OPT record.
// According to RFC 2671, "One OPT pseudo-RR can be added to the additional data section of either a request or a response."
// This implies that there may be *at most* one OPT record per DNS message, in the Additional Section,
// but not necessarily the *last* entry in the Additional Section.
for (i = 0; ptr && i < msg->h.numAdditionals; i++)
{
if (ptr + DNSOpt_Header_Space + minsize <= end && // Make sure we have 11+minsize bytes of data
ptr[0] == 0 && // Name must be root label
ptr[1] == (kDNSType_OPT >> 8 ) && // rrtype OPT
ptr[2] == (kDNSType_OPT & 0xFF) &&
((mDNSu16)ptr[9] << 8 | (mDNSu16)ptr[10]) >= (mDNSu16)minsize)
return(ptr);
else
ptr = skipResourceRecord(msg, ptr, end);
}
return(mDNSNULL);
}
// On success, GetLLQOptData returns pointer to storage within shared "m->rec";
// it is caller's responsibilty to clear m->rec.r.resrec.RecordType after use
// Note: An OPT RDataBody actually contains one or more variable-length rdataOPT objects packed together
// The code that currently calls this assumes there's only one, instead of iterating through the set
mDNSexport const rdataOPT *GetLLQOptData(mDNS *const m, const DNSMessage *const msg, const mDNSu8 *const end)
{
const mDNSu8 *ptr = LocateOptRR(msg, end, DNSOpt_LLQData_Space);
if (ptr)
{
ptr = GetLargeResourceRecord(m, msg, ptr, end, 0, kDNSRecordTypePacketAdd, &m->rec);
if (ptr && m->rec.r.resrec.RecordType != kDNSRecordTypePacketNegative) return(&m->rec.r.resrec.rdata->u.opt[0]);
}
return(mDNSNULL);
}
// Get the lease life of records in a dynamic update
mDNSexport mDNSBool GetPktLease(mDNS *const m, const DNSMessage *const msg, const mDNSu8 *const end, mDNSu32 *const lease)
{
const mDNSu8 *ptr = LocateOptRR(msg, end, DNSOpt_LeaseData_Space);
if (ptr)
{
ptr = GetLargeResourceRecord(m, msg, ptr, end, 0, kDNSRecordTypePacketAdd, &m->rec);
if (ptr && m->rec.r.resrec.RecordType != kDNSRecordTypePacketNegative && m->rec.r.resrec.rrtype == kDNSType_OPT)
{
const rdataOPT *o;
const rdataOPT *const e = (const rdataOPT *)&m->rec.r.resrec.rdata->u.data[m->rec.r.resrec.rdlength];
for (o = &m->rec.r.resrec.rdata->u.opt[0]; o < e; o++)
if (o->opt == kDNSOpt_Lease)
{
*lease = o->u.updatelease;
mDNSCoreResetRecord(m);
return mDNStrue;
}
}
mDNSCoreResetRecord(m);
}
return mDNSfalse;
}
#define DNS_OP_Name(X) ( \
(X) == kDNSFlag0_OP_StdQuery ? "" : \
(X) == kDNSFlag0_OP_Iquery ? "Iquery " : \
(X) == kDNSFlag0_OP_Status ? "Status " : \
(X) == kDNSFlag0_OP_Unused3 ? "Unused3 " : \
(X) == kDNSFlag0_OP_Notify ? "Notify " : \
(X) == kDNSFlag0_OP_Update ? "Update " : \
(X) == kDNSFlag0_OP_DSO ? "DSO " : "?? " )
#define DNS_RC_Name(X) ( \
(X) == kDNSFlag1_RC_NoErr ? "NoErr" : \
(X) == kDNSFlag1_RC_FormErr ? "FormErr" : \
(X) == kDNSFlag1_RC_ServFail ? "ServFail" : \
(X) == kDNSFlag1_RC_NXDomain ? "NXDomain" : \
(X) == kDNSFlag1_RC_NotImpl ? "NotImpl" : \
(X) == kDNSFlag1_RC_Refused ? "Refused" : \
(X) == kDNSFlag1_RC_YXDomain ? "YXDomain" : \
(X) == kDNSFlag1_RC_YXRRSet ? "YXRRSet" : \
(X) == kDNSFlag1_RC_NXRRSet ? "NXRRSet" : \
(X) == kDNSFlag1_RC_NotAuth ? "NotAuth" : \
(X) == kDNSFlag1_RC_NotZone ? "NotZone" : \
(X) == kDNSFlag1_RC_DSOTypeNI ? "DSOTypeNI" : "??" )
mDNSexport void mDNS_snprintf_add(char **ptr, const char *lim, const char *fmt, ...)
{
va_list args;
mDNSu32 buflen, n;
char *const dst = *ptr;
buflen = (mDNSu32)(lim - dst);
if (buflen > 0)
{
va_start(args, fmt);
n = mDNS_vsnprintf(dst, buflen, fmt, args);
va_end(args);
*ptr = dst + n;
}
}
#define DNSTypeString(X) (((X) == kDNSType_A) ? "A" : DNSTypeName(X))
mDNSlocal void DNSMessageDumpToLog(const DNSMessage *const msg, const mDNSu8 *const end)
{
domainname *name = mDNSNULL;
const mDNSu8 *ptr = msg->data;
domainname nameStorage[2];
char questions[512];
questions[0] = '\0';
char *questions_dst = questions;
const char *const questions_lim = &questions[512];
for (mDNSu32 i = 0; i < msg->h.numQuestions; i++)
{
mDNSu16 qtype, qclass;
name = &nameStorage[0];
ptr = getDomainName(msg, ptr, end, name);
if (!ptr) goto exit;
if ((end - ptr) < 4) goto exit;
qtype = ReadField16(&ptr[0]);
qclass = ReadField16(&ptr[2]);
ptr += 4;
mDNS_snprintf_add(&questions_dst, questions_lim, " %##s %s", name->c, DNSTypeString(qtype));
if (qclass != kDNSClass_IN) mDNS_snprintf_add(&questions_dst, questions_lim, "/%u", qclass);
mDNS_snprintf_add(&questions_dst, questions_lim, "?");
}
char rrs[512];
rrs[0] = '\0';
char *rrs_dst = rrs;
const char *const rrs_lim = &rrs[512];
const mDNSu32 rrcount = msg->h.numAnswers + msg->h.numAuthorities + msg->h.numAdditionals;
for (mDNSu32 i = 0; i < rrcount; i++)
{
mDNSu16 rrtype, rrclass, rdlength;
mDNSu32 ttl;
int handled;
const mDNSu8 *rdata;
const domainname *const previousName = name;
name = &nameStorage[(name == &nameStorage[0]) ? 1 : 0];
ptr = getDomainName(msg, ptr, end, name);
if (!ptr) goto exit;
if ((end - ptr) < 10) goto exit;
rrtype = ReadField16(&ptr[0]);
rrclass = ReadField16(&ptr[2]);
ttl = ReadField32(&ptr[4]);
rdlength = ReadField16(&ptr[8]);
ptr += 10;
if ((end - ptr) < rdlength) goto exit;
rdata = ptr;
if (i > 0) mDNS_snprintf_add(&rrs_dst, rrs_lim, ",");
if (!previousName || !SameDomainName(name, previousName)) mDNS_snprintf_add(&rrs_dst, rrs_lim, " %##s", name);
mDNS_snprintf_add(&rrs_dst, rrs_lim, " %s", DNSTypeString(rrtype));
if (rrclass != kDNSClass_IN) mDNS_snprintf_add(&rrs_dst, rrs_lim, "/%u", rrclass);
mDNS_snprintf_add(&rrs_dst, rrs_lim, " ");
handled = mDNSfalse;
switch (rrtype)
{
case kDNSType_A:
if (rdlength == 4)
{
mDNS_snprintf_add(&rrs_dst, rrs_lim, "%.4a", rdata);
handled = mDNStrue;
}
break;
case kDNSType_AAAA:
if (rdlength == 16)
{
mDNS_snprintf_add(&rrs_dst, rrs_lim, "%.16a", rdata);
handled = mDNStrue;
}
break;
case kDNSType_CNAME:
ptr = getDomainName(msg, rdata, end, name);
if (!ptr) goto exit;
mDNS_snprintf_add(&rrs_dst, rrs_lim, "%##s", name);
handled = mDNStrue;
break;
case kDNSType_SOA:
{
mDNSu32 serial, refresh, retry, expire, minimum;
domainname *const mname = &nameStorage[0];
domainname *const rname = &nameStorage[1];
name = mDNSNULL;
ptr = getDomainName(msg, rdata, end, mname);
if (!ptr) goto exit;
ptr = getDomainName(msg, ptr, end, rname);
if (!ptr) goto exit;
if ((end - ptr) < 20) goto exit;
serial = ReadField32(&ptr[0]);
refresh = ReadField32(&ptr[4]);
retry = ReadField32(&ptr[8]);
expire = ReadField32(&ptr[12]);
minimum = ReadField32(&ptr[16]);
mDNS_snprintf_add(&rrs_dst, rrs_lim, "%##s %##s %lu %lu %lu %lu %lu", mname, rname, (unsigned long)serial,
(unsigned long)refresh, (unsigned long)retry, (unsigned long)expire, (unsigned long)minimum);
handled = mDNStrue;
break;
}
default:
break;
}
if (!handled) mDNS_snprintf_add(&rrs_dst, rrs_lim, "RDATA[%u]: %.*H", rdlength, rdlength, rdata);
mDNS_snprintf_add(&rrs_dst, rrs_lim, " (%lu)", (unsigned long)ttl);
ptr = rdata + rdlength;
}
LogRedact(MDNS_LOG_CATEGORY_DEFAULT, MDNS_LOG_DEFAULT,
"[Q%u] DNS " PUB_S PUB_S " (%lu) (flags %02X%02X) RCODE: " PUB_S " (%d)" PUB_S PUB_S PUB_S PUB_S PUB_S PUB_S ":"
PRI_S " %u/%u/%u " PRI_S,
mDNSVal16(msg->h.id),
DNS_OP_Name(msg->h.flags.b[0] & kDNSFlag0_OP_Mask),
(msg->h.flags.b[0] & kDNSFlag0_QR_Response) ? "Response" : "Query",
(unsigned long)(end - (const mDNSu8 *)msg),
msg->h.flags.b[0], msg->h.flags.b[1],
DNS_RC_Name(msg->h.flags.b[1] & kDNSFlag1_RC_Mask),
msg->h.flags.b[1] & kDNSFlag1_RC_Mask,
(msg->h.flags.b[0] & kDNSFlag0_AA) ? " AA" : "",
(msg->h.flags.b[0] & kDNSFlag0_TC) ? " TC" : "",
(msg->h.flags.b[0] & kDNSFlag0_RD) ? " RD" : "",
(msg->h.flags.b[1] & kDNSFlag1_RA) ? " RA" : "",
(msg->h.flags.b[1] & kDNSFlag1_AD) ? " AD" : "",
(msg->h.flags.b[1] & kDNSFlag1_CD) ? " CD" : "",
questions, msg->h.numAnswers, msg->h.numAuthorities, msg->h.numAdditionals, rrs);
exit:
return;
}
mDNSlocal mDNSBool DNSMessageIsResponse(const DNSMessage *const msg)
{
return ((msg->h.flags.b[0] & kDNSFlag0_QR_Mask) == kDNSFlag0_QR_Response);
}
mDNSlocal mDNSBool DNSMessageIsQuery(const DNSMessage *const msg)
{
return !DNSMessageIsResponse(msg);
}
// This function calculates and checks the hash value of the current DNS message if it matches a previous one already.
mDNSlocal void DumpMDNSPacket_CalculateAndCheckIfMsgAppearsBefore(const DNSMessage *const msg, const mDNSu8 *const end,
const mDNSAddr *const srcaddr, const mDNSIPPort srcport, const mDNSAddr *const dstaddr, const mDNSIPPort dstport,
const mDNSu32 ifIndex, mDNSu32 *const outMsgHash, mDNSBool *const outMsgHashSame,
mDNSu32 *const outCompleteHash, mDNSBool *const outCompleteHashSame)
{
// We calculate two hash values with different hash algorithms to avoid having collisions frequently.
const mDNSu32 msgLen = sizeof(DNSMessageHeader) + (mDNSu32)(end - msg->data);
const mDNSu32 msgHash = mDNS_NonCryptoHash(mDNSNonCryptoHash_FNV1a, msg->h.id.b, msgLen);
const mDNSu32 msg2ndHash = mDNS_NonCryptoHash(mDNSNonCryptoHash_SDBM, msg->h.id.b, msgLen);
mdns_assign(outMsgHash, msgHash);
mDNSu32 completeHash = msgHash;
mDNSu32 complete2ndHash = msg2ndHash;
if (srcaddr != mDNSNULL)
{
const mDNSu8 *const bytes = srcaddr->ip.v4.b;
const mDNSu32 len = sizeof(srcaddr->ip.v4.b);
completeHash = mDNS_NonCryptoHashUpdateBytes(mDNSNonCryptoHash_FNV1a, completeHash, bytes, len);
completeHash = mDNS_NonCryptoHashUpdateBytes(mDNSNonCryptoHash_FNV1a, completeHash, srcport.b,
sizeof(srcport.b));
complete2ndHash = mDNS_NonCryptoHashUpdateBytes(mDNSNonCryptoHash_SDBM, complete2ndHash, bytes, len);
complete2ndHash = mDNS_NonCryptoHashUpdateBytes(mDNSNonCryptoHash_SDBM, complete2ndHash, srcport.b,
sizeof(srcport.b));
}
if (dstaddr != mDNSNULL)
{
const mDNSu8 *const bytes = dstaddr->ip.v4.b;
const mDNSu32 len = sizeof(dstaddr->ip.v4.b);
completeHash = mDNS_NonCryptoHashUpdateBytes(mDNSNonCryptoHash_FNV1a, completeHash, bytes, len);
completeHash = mDNS_NonCryptoHashUpdateBytes(mDNSNonCryptoHash_FNV1a, completeHash, dstport.b,
sizeof(dstport.b));
complete2ndHash = mDNS_NonCryptoHashUpdateBytes(mDNSNonCryptoHash_SDBM, complete2ndHash, bytes, len);
complete2ndHash = mDNS_NonCryptoHashUpdateBytes(mDNSNonCryptoHash_SDBM, complete2ndHash, dstport.b,
sizeof(dstport.b));
}
mDNSu8 ifIndexBytes[4];
putVal32(ifIndexBytes, ifIndex);
completeHash = mDNS_NonCryptoHashUpdateBytes(mDNSNonCryptoHash_FNV1a, completeHash, ifIndexBytes,
sizeof(ifIndexBytes));
complete2ndHash = mDNS_NonCryptoHashUpdateBytes(mDNSNonCryptoHash_SDBM, complete2ndHash, ifIndexBytes,
sizeof(ifIndexBytes));
mdns_assign(outCompleteHash, completeHash);
#define NUM_OF_SAVED_HASH_COUNT 20
mDNSu32 i;
mDNSu32 count;
static mDNSu32 previousMsgHashes[NUM_OF_SAVED_HASH_COUNT] = {0};
static mDNSu32 previousMsg2ndHashes[NUM_OF_SAVED_HASH_COUNT] = {0};
static mDNSu32 nextMsgHashSlot = 0;
static mDNSu32 nextMsgHashUninitializedSlot = 0;
mdns_compile_time_check_local(mdns_countof(previousMsgHashes) == mdns_countof(previousMsg2ndHashes));
mDNSBool msgHashSame = mDNSfalse;
count = Min(mdns_countof(previousMsgHashes), nextMsgHashUninitializedSlot);
for (i = 0; i < count; i++)
{
if (previousMsgHashes[i] == msgHash && previousMsg2ndHashes[i] == msg2ndHash)
{
msgHashSame = mDNStrue;
break;
}
}
if (!msgHashSame)
{
previousMsgHashes[nextMsgHashSlot] = msgHash;
previousMsg2ndHashes[nextMsgHashSlot] = msg2ndHash;
nextMsgHashSlot++;
nextMsgHashSlot %= mdns_countof(previousMsgHashes);
if (nextMsgHashUninitializedSlot < mdns_countof(previousMsgHashes))
{
nextMsgHashUninitializedSlot++;
}
}
mdns_assign(outMsgHashSame, msgHashSame);
static mDNSu32 previousCompleteHashes[NUM_OF_SAVED_HASH_COUNT] = {0};
static mDNSu32 previousComplete2ndHashes[NUM_OF_SAVED_HASH_COUNT] = {0};
static mDNSu32 nextCompleteHashSlot = 0;
static mDNSu32 nextCompleteHashUninitializedSlot = 0;
mdns_compile_time_check_local(mdns_countof(previousCompleteHashes) == mdns_countof(previousComplete2ndHashes));
mDNSBool completeHashSame = mDNSfalse;
count = Min(mdns_countof(previousCompleteHashes), nextCompleteHashUninitializedSlot);
for (i = 0; i < count; i++)
{
if (previousCompleteHashes[i] == completeHash && previousComplete2ndHashes[i] == complete2ndHash)
{
completeHashSame = mDNStrue;
break;
}
}
if (!completeHashSame)
{
previousCompleteHashes[nextCompleteHashSlot] = completeHash;
previousComplete2ndHashes[nextCompleteHashSlot] = complete2ndHash;
nextCompleteHashSlot++;
nextCompleteHashSlot %= mdns_countof(previousCompleteHashes);
if (nextCompleteHashUninitializedSlot < mdns_countof(previousCompleteHashes))
{
nextCompleteHashUninitializedSlot++;
}
}
mdns_assign(outCompleteHashSame, completeHashSame);
}
mDNSlocal mDNSBool DumpMDNSPacket_GetNameHashTypeClass(const DNSMessage *const msg, const mDNSu8 *ptr,
const mDNSu8 *const end, mDNSu32 *const outNameHash, mDNSu16 *const outType, mDNSu16 *const outClass)
{
mDNSBool found;
domainname name;
ptr = getDomainName(msg, ptr, end, &name);
const mDNSu32 nameHash = mDNS_NonCryptoHash(mDNSNonCryptoHash_FNV1a, name.c, DomainNameLength(&name));
mdns_require_action_quiet(ptr, exit, found = mDNSfalse);
mdns_require_action_quiet(ptr + 4 <= end, exit, found = mDNSfalse);
const mDNSu16 type = ReadField16(&ptr[0]);
mDNSu16 class = ReadField16(&ptr[2]);
const mDNSBool isMDNS = mDNSOpaque16IsZero(msg->h.id);
if (isMDNS)
{
class &= kDNSClass_Mask;
}
mdns_assign(outNameHash, nameHash);
mdns_assign(outType, type);
mdns_assign(outClass, class);
found = mDNStrue;
exit:
return found;
}
// Each name hash/type pair contains 4-byte uint32_t hash value and 2-byte uint16_t type value, in network byte order.
#define DumpMDNSPacket_PairLen (sizeof(mDNSu32) + sizeof(mDNSu16))
// Currently, we only log the first 10 pairs.
#define DumpMDNSPacket_MaxPairCount 10
// The buffer size to hold the bytes.
#define DumpMDNSPacket_MaxBytesLen (DumpMDNSPacket_PairLen * DumpMDNSPacket_MaxPairCount)
mDNSlocal mStatus DumpMDNSPacket_GetNameHashTypeArray(const DNSMessage *const msg, const mDNSu8 *const end,
mDNSu8 *const inOutNameHashTypeArray, const mDNSu32 maxByteCount, mDNSu32 *const outByteCount)
{
mStatus err;
const mDNSu8 *ptr_to_read;
mDNSu8 *ptr_to_write = inOutNameHashTypeArray;
mDNSu32 pairCount = 0;
const mDNSu32 maxPairCount = maxByteCount / DumpMDNSPacket_PairLen;
const DNSMessageHeader *const hdr = &msg->h;
ptr_to_read = (const mDNSu8 *)msg->data;
for (mDNSu32 i = 0; i < hdr->numQuestions && pairCount < maxPairCount; i++, pairCount++)
{
mDNSu32 qnameHash;
mDNSu16 type;
const mDNSBool found = DumpMDNSPacket_GetNameHashTypeClass(msg, ptr_to_read, end, &qnameHash, &type, mDNSNULL);
mdns_require_action_quiet(found, exit, err = mStatus_Invalid);
ptr_to_write = putVal32(ptr_to_write, qnameHash);
ptr_to_write = putVal16(ptr_to_write, type);
ptr_to_read = skipQuestion(msg, ptr_to_read, end);
mdns_require_action_quiet(ptr_to_read, exit, err = mStatus_Invalid);
}
for (mDNSu32 i = 0; i < hdr->numAnswers && pairCount < maxPairCount; i++, pairCount++)
{
mDNSu32 nameHash;
mDNSu16 type;
const mDNSBool found = DumpMDNSPacket_GetNameHashTypeClass(msg, ptr_to_read, end, &nameHash, &type, mDNSNULL);
mdns_require_action_quiet(found, exit, err = mStatus_Invalid);
ptr_to_write = putVal32(ptr_to_write, nameHash);
ptr_to_write = putVal16(ptr_to_write, type);
ptr_to_read = skipResourceRecord(msg, ptr_to_read, end);
mdns_require_action_quiet(ptr_to_read, exit, err = mStatus_Invalid);
}
for (mDNSu32 i = 0; i < hdr->numAuthorities && pairCount < maxPairCount; i++, pairCount++)
{
mDNSu32 nameHash;
mDNSu16 type;
const mDNSBool found = DumpMDNSPacket_GetNameHashTypeClass(msg, ptr_to_read, end, &nameHash, &type, mDNSNULL);
mdns_require_action_quiet(found, exit, err = mStatus_Invalid);
ptr_to_write = putVal32(ptr_to_write, nameHash);
ptr_to_write = putVal16(ptr_to_write, type);
ptr_to_read = skipResourceRecord(msg, ptr_to_read, end);
mdns_require_action_quiet(ptr_to_read, exit, err = mStatus_Invalid);
}
for (mDNSu32 i = 0; i < hdr->numAdditionals && pairCount < maxPairCount; i++, pairCount++)
{
mDNSu32 nameHash;
mDNSu16 type;
const mDNSBool found = DumpMDNSPacket_GetNameHashTypeClass(msg, ptr_to_read, end, &nameHash, &type, mDNSNULL);
mdns_require_action_quiet(found, exit, err = mStatus_Invalid);
ptr_to_write = putVal32(ptr_to_write, nameHash);
ptr_to_write = putVal16(ptr_to_write, type);
ptr_to_read = skipResourceRecord(msg, ptr_to_read, end);
mdns_require_action_quiet(ptr_to_read, exit, err = mStatus_Invalid);
}
err = mStatus_NoError;
exit:
mdns_assign(outByteCount, pairCount * DumpMDNSPacket_PairLen);
return err;
}
mDNSlocal void DumpMDNSPacket(const mDNSBool sent, const DNSMessage *const msg, const mDNSu8 *const end,
const mDNSAddr *const srcaddr, const mDNSIPPort srcport, const mDNSAddr *const dstaddr, const mDNSIPPort dstport,
const mDNSu32 ifIndex, const char *const ifName)
{
const mDNSu32 msgLen = sizeof(DNSMessageHeader) + (mDNSu32)(end - msg->data);
const mDNSBool query = DNSMessageIsQuery(msg);
const mDNSBool unicastAssisted = (dstaddr && !mDNSAddrIsDNSMulticast(dstaddr) &&
mDNSSameIPPort(dstport, MulticastDNSPort));
mDNSu32 msgHash; // Hash of the DNS message.
mDNSBool sameMsg; // If the hash matches a previous DNS message.
mDNSu32 completeMsgHash; // Hash of the DNS message, source address/port, destination address/port.
mDNSBool sameCompleteMsg; // If the hash matches a previous DNS message that is sent from the same source host to
// the same destination host.
DumpMDNSPacket_CalculateAndCheckIfMsgAppearsBefore(msg, end, srcaddr, srcport, dstaddr, dstport, ifIndex, &msgHash,
&sameMsg, &completeMsgHash, &sameCompleteMsg);
// The header fields are already in host byte order.
DNSMessageHeader hdr = msg->h;
// Check if it is IPv6 or IPv4 message.
mDNSBool ipv6Msg = mDNSfalse;
if (srcaddr && srcaddr->type == mDNSAddrType_IPv6)
{
ipv6Msg = mDNStrue;
}
else if (dstaddr && dstaddr->type == mDNSAddrType_IPv6)
{
ipv6Msg = mDNStrue;
}
#if MDNSRESPONDER_SUPPORTS(APPLE, OS_LOG)
// The os_log specifier requires network byte order data.
SwapDNSHeaderBytesWithHeader(&hdr);
const mDNSu32 IDFlags = ReadField32(hdr.id.b);
const uint64_t counts = ReadField64(&hdr.numQuestions);
SwapDNSHeaderBytesWithHeader(&hdr);
#endif
// Get the (Name hash, Type) bytes array from the DNS message, where name is converted to a 4-byte hash value
// type is converted to a 2-byte value.
mDNSu8 nameHashTypeBytes[DumpMDNSPacket_MaxBytesLen];
mDNSu32 nameHashTypeBytesLen;
if (!sameMsg)
{
// Only calculate the name hash type bytes when we have not seen this message recently.
DumpMDNSPacket_GetNameHashTypeArray(msg, end, nameHashTypeBytes, sizeof(nameHashTypeBytes),
&nameHashTypeBytesLen);
}
else
{
nameHashTypeBytesLen = 0;
}
// Note:
// 1. There are two hash values printed for the message logging in `[Q(%x, %x)]`.
// a) The first value is the FNV-1a hash of the entire DNS message, the first value can be used to easily
// identify the same DNS message quickly.
// b) The second value is the FNV-1a hash of the entire DNS message, plus source address, source port,
// destination address, destination port and interface index. This value can be used to easily identify
// repetitive message transmission.
// c) The two hash values above are also used to avoid unnecessary duplicate logs by checking the hash values of
// the recent DNS message (currently recent means recent 20 messages).
// d) We use two separate hash algorithms to check if the message has occurred recently, but we only print
// FNV-1a hash values.
// 2. For all "Send" events, we do not log destination address because it is always the corresponding multicast
// address, there is no need to log them over and over again.
// 3. We print "query", "response" according to the type of the DNS message.
// 4. If we have not seen the DNS message before, the message header, the record count section will be printed. Also
// the first 10 "(name hash, type)" pairs will be printed to provide more context.
// 5. For the "Receive" event, we log source address so that we know where the query or response comes from.
if (unicastAssisted) // unicast DNS
{
if (ipv6Msg) // IPv6
{
if (sent) // Send
{
if (query) // Query
{
if (sameCompleteMsg)
{
LogRedact(MDNS_LOG_CATEGORY_MDNS, MDNS_LOG_DEFAULT,
"[Q(%x, %x)] Sent a previous IPv6 mDNS query over unicast", msgHash, completeMsgHash);
}
else if (sameMsg)
{
LogRedact(MDNS_LOG_CATEGORY_MDNS, MDNS_LOG_DEFAULT,
"[Q(%x, %x)] Sent a previous IPv6 mDNS query to " PRI_IP_ADDR " over unicast via " PUB_S
"/%u", msgHash, completeMsgHash, dstaddr, ifName, ifIndex);
}
else
{
LogRedact(MDNS_LOG_CATEGORY_MDNS, MDNS_LOG_DEFAULT,
"[Q(%x, %x)] Sent %u-byte IPv6 mDNS query to " PRI_IP_ADDR " over unicast via " PUB_S "/%u "
"-- " DNS_MSG_ID_FLAGS ", counts: " DNS_MSG_COUNTS " " MDNS_NAME_HASH_TYPE_BYTES, msgHash,
completeMsgHash, msgLen, dstaddr, ifName, ifIndex, DNS_MSG_ID_FLAGS_PARAM(hdr, IDFlags),
DNS_MSG_COUNTS_PARAM(hdr, counts),
MDNS_NAME_HASH_TYPE_BYTES_PARAM(nameHashTypeBytes, nameHashTypeBytesLen));
}
}
else // Response
{
if (sameCompleteMsg)
{
LogRedact(MDNS_LOG_CATEGORY_MDNS, MDNS_LOG_DEFAULT,
"[A(%x, %x)] Sent a previous IPv6 mDNS response over unicast", msgHash, completeMsgHash);
}
else if (sameMsg)
{
LogRedact(MDNS_LOG_CATEGORY_MDNS, MDNS_LOG_DEFAULT,
"[A(%x, %x)] Sent a previous IPv6 mDNS response to " PRI_IP_ADDR " over unicast via " PUB_S
"/%u", msgHash, completeMsgHash, dstaddr, ifName, ifIndex);
}
else
{
LogRedact(MDNS_LOG_CATEGORY_MDNS, MDNS_LOG_DEFAULT,
"[A(%x, %x)] Sent %u-byte IPv6 mDNS response to " PRI_IP_ADDR " over unicast via " PUB_S
"/%u -- " DNS_MSG_ID_FLAGS ", counts: " DNS_MSG_COUNTS " " MDNS_NAME_HASH_TYPE_BYTES,
msgHash, completeMsgHash, msgLen, dstaddr, ifName, ifIndex,
DNS_MSG_ID_FLAGS_PARAM(hdr, IDFlags), DNS_MSG_COUNTS_PARAM(hdr, counts),
MDNS_NAME_HASH_TYPE_BYTES_PARAM(nameHashTypeBytes, nameHashTypeBytesLen));
}
}
}
else // Receive
{
if (query) // Query
{
if (sameCompleteMsg)
{
LogRedact(MDNS_LOG_CATEGORY_MDNS, MDNS_LOG_DEFAULT,
"[A(%x, %x)] Received a previous IPv6 mDNS query over unicast",
msgHash, completeMsgHash);
}
else if (sameMsg)
{
LogRedact(MDNS_LOG_CATEGORY_MDNS, MDNS_LOG_DEFAULT,
"[A(%x, %x)] Received a previous IPv6 mDNS query from " PRI_IP_ADDR " over unicast via "
PUB_S "/%u", msgHash, completeMsgHash, srcaddr, ifName, ifIndex);
}
else
{
LogRedact(MDNS_LOG_CATEGORY_MDNS, MDNS_LOG_DEFAULT,
"[A(%x, %x)] Received %u-byte IPv6 mDNS query from " PRI_IP_ADDR " over unicast via " PUB_S
"/%u -- " DNS_MSG_ID_FLAGS ", counts: " DNS_MSG_COUNTS " " MDNS_NAME_HASH_TYPE_BYTES,
msgHash, completeMsgHash, msgLen, srcaddr, ifName, ifIndex,
DNS_MSG_ID_FLAGS_PARAM(hdr, IDFlags), DNS_MSG_COUNTS_PARAM(hdr, counts),
MDNS_NAME_HASH_TYPE_BYTES_PARAM(nameHashTypeBytes, nameHashTypeBytesLen));
}
}
else // Response
{
if (sameCompleteMsg)
{
LogRedact(MDNS_LOG_CATEGORY_MDNS, MDNS_LOG_DEFAULT,
"[Q(%x, %x)] Received a previous IPv6 mDNS response over unicast",
msgHash, completeMsgHash);
}
else if (sameMsg)
{
LogRedact(MDNS_LOG_CATEGORY_MDNS, MDNS_LOG_DEFAULT,
"[Q(%x, %x)] Received a previous IPv6 mDNS response from " PRI_IP_ADDR " over unicast via "
PUB_S "/%u", msgHash, completeMsgHash, srcaddr, ifName, ifIndex);
}
else
{
LogRedact(MDNS_LOG_CATEGORY_MDNS, MDNS_LOG_DEFAULT,
"[Q(%x, %x)] Received %u-byte IPv6 mDNS response from " PRI_IP_ADDR " over unicast via "
PUB_S "/%u -- " DNS_MSG_ID_FLAGS ", counts: " DNS_MSG_COUNTS " " MDNS_NAME_HASH_TYPE_BYTES,
msgHash, completeMsgHash, msgLen, srcaddr, ifName, ifIndex,
DNS_MSG_ID_FLAGS_PARAM(hdr, IDFlags), DNS_MSG_COUNTS_PARAM(hdr, counts),
MDNS_NAME_HASH_TYPE_BYTES_PARAM(nameHashTypeBytes, nameHashTypeBytesLen));
}
}
}
}
else // IPv4
{
if (sent) // Send
{
if (query) // Query
{
if (sameCompleteMsg)
{
LogRedact(MDNS_LOG_CATEGORY_MDNS, MDNS_LOG_DEFAULT,
"[Q(%x, %x)] Sent a previous IPv4 mDNS query over unicast", msgHash, completeMsgHash);
}
else if (sameMsg)
{
LogRedact(MDNS_LOG_CATEGORY_MDNS, MDNS_LOG_DEFAULT,
"[Q(%x, %x)] Sent a previous IPv4 mDNS query to " PRI_IP_ADDR " over unicast via " PUB_S
"/%u", msgHash, completeMsgHash, dstaddr, ifName, ifIndex);
}
else
{
LogRedact(MDNS_LOG_CATEGORY_MDNS, MDNS_LOG_DEFAULT,
"[Q(%x, %x)] Sent %u-byte IPv4 mDNS query to " PRI_IP_ADDR " over unicast via " PUB_S "/%u "
"-- " DNS_MSG_ID_FLAGS ", counts: " DNS_MSG_COUNTS " " MDNS_NAME_HASH_TYPE_BYTES, msgHash,
completeMsgHash, msgLen, dstaddr, ifName, ifIndex, DNS_MSG_ID_FLAGS_PARAM(hdr, IDFlags),
DNS_MSG_COUNTS_PARAM(hdr, counts),
MDNS_NAME_HASH_TYPE_BYTES_PARAM(nameHashTypeBytes, nameHashTypeBytesLen));
}
}
else // Response
{
if (sameCompleteMsg)
{
LogRedact(MDNS_LOG_CATEGORY_MDNS, MDNS_LOG_DEFAULT,
"[A(%x, %x)] Sent a previous IPv4 mDNS response over unicast", msgHash, completeMsgHash);
}
else if (sameMsg)
{
LogRedact(MDNS_LOG_CATEGORY_MDNS, MDNS_LOG_DEFAULT,
"[A(%x, %x)] Sent a previous IPv4 mDNS response to " PRI_IP_ADDR " over unicast via " PUB_S
"/%u", msgHash, completeMsgHash, dstaddr, ifName, ifIndex);
}
else
{
LogRedact(MDNS_LOG_CATEGORY_MDNS, MDNS_LOG_DEFAULT,
"[A(%x, %x)] Sent %u-byte IPv4 mDNS response to " PRI_IP_ADDR " over unicast via " PUB_S
"/%u -- " DNS_MSG_ID_FLAGS ", counts: " DNS_MSG_COUNTS " " MDNS_NAME_HASH_TYPE_BYTES,
msgHash, completeMsgHash, msgLen, dstaddr, ifName, ifIndex,
DNS_MSG_ID_FLAGS_PARAM(hdr, IDFlags), DNS_MSG_COUNTS_PARAM(hdr, counts),
MDNS_NAME_HASH_TYPE_BYTES_PARAM(nameHashTypeBytes, nameHashTypeBytesLen));
}
}
}
else // Receive
{
if (query) // Query
{
if (sameCompleteMsg)
{
LogRedact(MDNS_LOG_CATEGORY_MDNS, MDNS_LOG_DEFAULT,
"[A(%x, %x)] Received a previous IPv4 mDNS query over unicast",
msgHash, completeMsgHash);
}
else if (sameMsg)
{
LogRedact(MDNS_LOG_CATEGORY_MDNS, MDNS_LOG_DEFAULT,
"[A(%x, %x)] Received a previous IPv4 mDNS query from " PRI_IP_ADDR " over unicast via "
PUB_S "/%u", msgHash, completeMsgHash, srcaddr, ifName, ifIndex);
}
else
{
LogRedact(MDNS_LOG_CATEGORY_MDNS, MDNS_LOG_DEFAULT,
"[A(%x, %x)] Received %u-byte IPv4 mDNS query from " PRI_IP_ADDR " over unicast via " PUB_S
"/%u -- " DNS_MSG_ID_FLAGS ", counts: " DNS_MSG_COUNTS " " MDNS_NAME_HASH_TYPE_BYTES,
msgHash, completeMsgHash, msgLen, srcaddr, ifName, ifIndex,
DNS_MSG_ID_FLAGS_PARAM(hdr, IDFlags), DNS_MSG_COUNTS_PARAM(hdr, counts),
MDNS_NAME_HASH_TYPE_BYTES_PARAM(nameHashTypeBytes, nameHashTypeBytesLen));
}
}
else // Response
{
if (sameCompleteMsg)
{
LogRedact(MDNS_LOG_CATEGORY_MDNS, MDNS_LOG_DEFAULT,
"[Q(%x, %x)] Received a previous IPv4 mDNS response over unicast",
msgHash, completeMsgHash);
}
else if (sameMsg)
{
LogRedact(MDNS_LOG_CATEGORY_MDNS, MDNS_LOG_DEFAULT,
"[Q(%x, %x)] Received a previous IPv4 mDNS response from " PRI_IP_ADDR " over unicast via "
PUB_S "/%u", msgHash, completeMsgHash, srcaddr, ifName, ifIndex);
}
else
{
LogRedact(MDNS_LOG_CATEGORY_MDNS, MDNS_LOG_DEFAULT,
"[Q(%x, %x)] Received %u-byte IPv4 mDNS response from " PRI_IP_ADDR " over unicast via "
PUB_S "/%u -- " DNS_MSG_ID_FLAGS ", counts: " DNS_MSG_COUNTS " " MDNS_NAME_HASH_TYPE_BYTES,
msgHash, completeMsgHash, msgLen, srcaddr, ifName, ifIndex,
DNS_MSG_ID_FLAGS_PARAM(hdr, IDFlags), DNS_MSG_COUNTS_PARAM(hdr, counts),
MDNS_NAME_HASH_TYPE_BYTES_PARAM(nameHashTypeBytes, nameHashTypeBytesLen));
}
}
}
}
}
else // multicast DNS
{
if (ipv6Msg) // IPv6
{
if (sent) // Send
{
if (query) // Query
{
if (sameCompleteMsg)
{
LogRedact(MDNS_LOG_CATEGORY_MDNS, MDNS_LOG_DEFAULT,
"[Q(%x, %x)] Sent a previous IPv6 mDNS query over multicast", msgHash, completeMsgHash);
}
else if (sameMsg)
{
LogRedact(MDNS_LOG_CATEGORY_MDNS, MDNS_LOG_DEFAULT,
"[Q(%x, %x)] Sent a previous IPv6 mDNS query over multicast via " PUB_S "/%u", msgHash,
completeMsgHash, ifName, ifIndex);
}
else
{
LogRedact(MDNS_LOG_CATEGORY_MDNS, MDNS_LOG_DEFAULT,
"[Q(%x, %x)] Sent %u-byte IPv6 mDNS query over multicast via " PUB_S "/%u -- "
DNS_MSG_ID_FLAGS ", counts: " DNS_MSG_COUNTS " " MDNS_NAME_HASH_TYPE_BYTES,
msgHash, completeMsgHash, msgLen, ifName, ifIndex, DNS_MSG_ID_FLAGS_PARAM(hdr, IDFlags),
DNS_MSG_COUNTS_PARAM(hdr, counts),
MDNS_NAME_HASH_TYPE_BYTES_PARAM(nameHashTypeBytes, nameHashTypeBytesLen));
}
}
else // Response
{
if (sameCompleteMsg)
{
LogRedact(MDNS_LOG_CATEGORY_MDNS, MDNS_LOG_DEFAULT,
"[A(%x, %x)] Sent a previous IPv6 mDNS response over multicast", msgHash, completeMsgHash);
}
else if (sameMsg)
{
LogRedact(MDNS_LOG_CATEGORY_MDNS, MDNS_LOG_DEFAULT,
"[A(%x, %x)] Sent a previous IPv6 mDNS response over multicast via " PUB_S "/%u", msgHash,
completeMsgHash, ifName, ifIndex);
}
else
{
LogRedact(MDNS_LOG_CATEGORY_MDNS, MDNS_LOG_DEFAULT,
"[A(%x, %x)] Sent %u-byte IPv6 mDNS response over multicast via " PUB_S "/%u -- "
DNS_MSG_ID_FLAGS ", counts: " DNS_MSG_COUNTS " " MDNS_NAME_HASH_TYPE_BYTES,
msgHash, completeMsgHash, msgLen, ifName, ifIndex, DNS_MSG_ID_FLAGS_PARAM(hdr, IDFlags),
DNS_MSG_COUNTS_PARAM(hdr, counts),
MDNS_NAME_HASH_TYPE_BYTES_PARAM(nameHashTypeBytes, nameHashTypeBytesLen));
}
}
}
else // Receive
{
if (query) // Query
{
if (sameCompleteMsg)
{
LogRedact(MDNS_LOG_CATEGORY_MDNS, MDNS_LOG_DEFAULT,
"[A(%x, %x)] Received a previous IPv6 mDNS query over multicast", msgHash,
completeMsgHash);
}
else if (sameMsg)
{
LogRedact(MDNS_LOG_CATEGORY_MDNS, MDNS_LOG_DEFAULT,
"[A(%x, %x)] Received a previous IPv6 mDNS query from " PRI_IP_ADDR
" over multicast via " PUB_S "/%u", msgHash, completeMsgHash, srcaddr, ifName,
ifIndex);
}
else
{
LogRedact(MDNS_LOG_CATEGORY_MDNS, MDNS_LOG_DEFAULT,
"[A(%x, %x)] Received %u-byte IPv6 mDNS query from " PRI_IP_ADDR
" over multicast via " PUB_S "/%u -- " DNS_MSG_ID_FLAGS ", counts: " DNS_MSG_COUNTS
" " MDNS_NAME_HASH_TYPE_BYTES, msgHash,
completeMsgHash, msgLen, srcaddr, ifName, ifIndex,
DNS_MSG_ID_FLAGS_PARAM(hdr, IDFlags), DNS_MSG_COUNTS_PARAM(hdr, counts),
MDNS_NAME_HASH_TYPE_BYTES_PARAM(nameHashTypeBytes, nameHashTypeBytesLen));
}
}
else // Response
{
if (sameCompleteMsg)
{
LogRedact(MDNS_LOG_CATEGORY_MDNS, MDNS_LOG_DEFAULT,
"[Q(%x, %x)] Received a previous IPv6 mDNS response over multicast",
msgHash, completeMsgHash);
}
else if (sameMsg)
{
LogRedact(MDNS_LOG_CATEGORY_MDNS, MDNS_LOG_DEFAULT,
"[Q(%x, %x)] Received a previous IPv6 mDNS response from " PRI_IP_ADDR
" over multicast via " PUB_S "/%u", msgHash, completeMsgHash, srcaddr, ifName,
ifIndex);
}
else
{
LogRedact(MDNS_LOG_CATEGORY_MDNS, MDNS_LOG_DEFAULT,
"[Q(%x, %x)] Received %u-byte IPv6 mDNS response from " PRI_IP_ADDR
" over multicast via " PUB_S "/%u -- " DNS_MSG_ID_FLAGS ", counts: " DNS_MSG_COUNTS
" " MDNS_NAME_HASH_TYPE_BYTES, msgHash, completeMsgHash, msgLen, srcaddr, ifName,
ifIndex, DNS_MSG_ID_FLAGS_PARAM(hdr, IDFlags), DNS_MSG_COUNTS_PARAM(hdr, counts),
MDNS_NAME_HASH_TYPE_BYTES_PARAM(nameHashTypeBytes, nameHashTypeBytesLen));
}
}
}
}
else // IPv4
{
if (sent) // Send
{
if (query) // Query
{
if (sameCompleteMsg)
{
LogRedact(MDNS_LOG_CATEGORY_MDNS, MDNS_LOG_DEFAULT,
"[Q(%x, %x)] Sent a previous IPv4 mDNS query over multicast", msgHash, completeMsgHash);
}
else if (sameMsg)
{
LogRedact(MDNS_LOG_CATEGORY_MDNS, MDNS_LOG_DEFAULT,
"[Q(%x, %x)] Sent a previous IPv4 mDNS query over multicast via " PUB_S "/%u", msgHash,
completeMsgHash, ifName, ifIndex);
}
else
{
LogRedact(MDNS_LOG_CATEGORY_MDNS, MDNS_LOG_DEFAULT,
"[Q(%x, %x)] Sent %u-byte IPv4 mDNS query over multicast via " PUB_S "/%u -- "
DNS_MSG_ID_FLAGS ", counts: " DNS_MSG_COUNTS " " MDNS_NAME_HASH_TYPE_BYTES,
msgHash, completeMsgHash, msgLen, ifName, ifIndex, DNS_MSG_ID_FLAGS_PARAM(hdr, IDFlags),
DNS_MSG_COUNTS_PARAM(hdr, counts),
MDNS_NAME_HASH_TYPE_BYTES_PARAM(nameHashTypeBytes, nameHashTypeBytesLen));
}
}
else // Response
{
if (sameCompleteMsg)
{
LogRedact(MDNS_LOG_CATEGORY_MDNS, MDNS_LOG_DEFAULT,
"[A(%x, %x)] Sent a previous IPv4 mDNS response over multicast", msgHash, completeMsgHash);
}
else if (sameMsg)
{
LogRedact(MDNS_LOG_CATEGORY_MDNS, MDNS_LOG_DEFAULT,
"[A(%x, %x)] Sent a previous IPv4 mDNS response over multicast via " PUB_S "/%u", msgHash,
completeMsgHash, ifName, ifIndex);
}
else
{
LogRedact(MDNS_LOG_CATEGORY_MDNS, MDNS_LOG_DEFAULT,
"[A(%x, %x)] Sent %u-byte IPv4 mDNS response over multicast via " PUB_S "/%u -- "
DNS_MSG_ID_FLAGS ", counts: " DNS_MSG_COUNTS " " MDNS_NAME_HASH_TYPE_BYTES,
msgHash, completeMsgHash, msgLen, ifName, ifIndex, DNS_MSG_ID_FLAGS_PARAM(hdr, IDFlags),
DNS_MSG_COUNTS_PARAM(hdr, counts),
MDNS_NAME_HASH_TYPE_BYTES_PARAM(nameHashTypeBytes, nameHashTypeBytesLen));
}
}
}
else // Receive
{
if (query) // Query
{
if (sameCompleteMsg)
{
LogRedact(MDNS_LOG_CATEGORY_MDNS, MDNS_LOG_DEFAULT,
"[A(%x, %x)] Received a previous IPv4 mDNS query over multicast", msgHash,
completeMsgHash);
}
else if (sameMsg)
{
LogRedact(MDNS_LOG_CATEGORY_MDNS, MDNS_LOG_DEFAULT,
"[A(%x, %x)] Received a previous IPv4 mDNS query from " PRI_IP_ADDR
" over multicast via " PUB_S "/%u", msgHash, completeMsgHash, srcaddr, ifName,
ifIndex);
}
else
{
LogRedact(MDNS_LOG_CATEGORY_MDNS, MDNS_LOG_DEFAULT,
"[A(%x, %x)] Received %u-byte IPv4 mDNS query from " PRI_IP_ADDR " over multicast"
" via " PUB_S "/%u -- " DNS_MSG_ID_FLAGS ", counts: " DNS_MSG_COUNTS " "
MDNS_NAME_HASH_TYPE_BYTES, msgHash, completeMsgHash, msgLen, srcaddr, ifName,
ifIndex, DNS_MSG_ID_FLAGS_PARAM(hdr, IDFlags), DNS_MSG_COUNTS_PARAM(hdr, counts),
MDNS_NAME_HASH_TYPE_BYTES_PARAM(nameHashTypeBytes, nameHashTypeBytesLen));
}
}
else // Response
{
if (sameCompleteMsg)
{
LogRedact(MDNS_LOG_CATEGORY_MDNS, MDNS_LOG_DEFAULT,
"[Q(%x, %x)] Received a previous IPv4 mDNS response over multicast",
msgHash, completeMsgHash);
}
else if (sameMsg)
{
LogRedact(MDNS_LOG_CATEGORY_MDNS, MDNS_LOG_DEFAULT,
"[Q(%x, %x)] Received a previous IPv4 mDNS response from " PRI_IP_ADDR
" over multicast via " PUB_S "/%u", msgHash, completeMsgHash, srcaddr, ifName,
ifIndex);
}
else
{
LogRedact(MDNS_LOG_CATEGORY_MDNS, MDNS_LOG_DEFAULT,
"[Q(%x, %x)] Received %u-byte IPv4 mDNS response from " PRI_IP_ADDR
" over multicast via " PUB_S "/%u -- " DNS_MSG_ID_FLAGS ", counts: " DNS_MSG_COUNTS
" " MDNS_NAME_HASH_TYPE_BYTES, msgHash, completeMsgHash, msgLen, srcaddr, ifName,
ifIndex, DNS_MSG_ID_FLAGS_PARAM(hdr, IDFlags), DNS_MSG_COUNTS_PARAM(hdr, counts),
MDNS_NAME_HASH_TYPE_BYTES_PARAM(nameHashTypeBytes, nameHashTypeBytesLen));
}
}
}
}
}
}
// Note: DumpPacket expects the packet header fields in host byte order, not network byte order
mDNSexport void DumpPacket(mStatus status, mDNSBool sent, const char *transport,
const mDNSAddr *srcaddr, mDNSIPPort srcport,const mDNSAddr *dstaddr, mDNSIPPort dstport, const DNSMessage *const msg,
const mDNSu8 *const end, mDNSInterfaceID interfaceID)
{
const mDNSAddr zeroIPv4Addr = { mDNSAddrType_IPv4, {{{ 0 }}} };
char action[32];
if (!status) mDNS_snprintf(action, sizeof(action), sent ? "Sent" : "Received");
else mDNS_snprintf(action, sizeof(action), "ERROR %d %sing", status, sent ? "Send" : "Receiv");
#if __APPLE__
const mDNSu32 interfaceIndex = IIDPrintable(interfaceID);
const char *const interfaceName = InterfaceNameForID(&mDNSStorage, interfaceID);
#else
const mDNSu32 interfaceIndex = mDNSPlatformInterfaceIndexfromInterfaceID(&mDNSStorage, interfaceID, mDNStrue);
const char *const interfaceName = "interface";
#endif
if (!mDNSOpaque16IsZero(msg->h.id))
{
LogRedact(MDNS_LOG_CATEGORY_DEFAULT, MDNS_LOG_DEFAULT, "[Q%u] " PUB_S " " PUB_S " DNS Message %lu bytes from "
PRI_IP_ADDR ":%d to " PRI_IP_ADDR ":%d via " PUB_S " (%p)", mDNSVal16(msg->h.id), action, transport,
(unsigned long)(end - (const mDNSu8 *)msg), srcaddr ? srcaddr : &zeroIPv4Addr, mDNSVal16(srcport),
dstaddr ? dstaddr : &zeroIPv4Addr, mDNSVal16(dstport), interfaceName, interfaceID);
DNSMessageDumpToLog(msg, end);
}
else
{
DumpMDNSPacket(sent, msg, end, srcaddr, srcport, dstaddr, dstport, interfaceIndex, interfaceName);
if (status)
{
if (sent)
{
LogRedact(MDNS_LOG_CATEGORY_MDNS, MDNS_LOG_ERROR,
"Sending mDNS message failed - mStatus: %d", status);
}
else
{
LogRedact(MDNS_LOG_CATEGORY_MDNS, MDNS_LOG_ERROR,
"Receiving mDNS message failed - mStatus: %d", status);
}
}
}
}
// ***************************************************************************
// MARK: - Packet Sending Functions
// Stub definition of TCPSocket_struct so we can access flags field. (Rest of TCPSocket_struct is platform-dependent.)
struct TCPSocket_struct { mDNSIPPort port; TCPSocketFlags flags; /* ... */ };
// Stub definition of UDPSocket_struct so we can access port field. (Rest of UDPSocket_struct is platform-dependent.)
struct UDPSocket_struct { mDNSIPPort port; /* ... */ };
// Note: When we sign a DNS message using DNSDigest_SignMessage(), the current real-time clock value is used, which
// is why we generally defer signing until we send the message, to ensure the signature is as fresh as possible.
mDNSexport mStatus mDNSSendDNSMessage(mDNS *const m, DNSMessage *const msg, mDNSu8 *end,
mDNSInterfaceID InterfaceID, TCPSocket *tcpSrc, UDPSocket *udpSrc, const mDNSAddr *dst,
mDNSIPPort dstport, DomainAuthInfo *authInfo, mDNSBool useBackgroundTrafficClass)
{
mStatus status = mStatus_NoError;
const mDNSu16 numAdditionals = msg->h.numAdditionals;
// Zero-length message data is okay (e.g. for a DNS Update ack, where all we need is an ID and an error code)
if (end < msg->data || end - msg->data > AbsoluteMaxDNSMessageData)
{
LogRedact(MDNS_LOG_CATEGORY_DEFAULT, MDNS_LOG_DEFAULT, "mDNSSendDNSMessage: invalid message %p %p %ld", msg->data, end, end - msg->data);
return mStatus_BadParamErr;
}
// Put all the integer values in IETF byte-order (MSB first, LSB second)
SwapDNSHeaderBytes(msg);
if (authInfo) DNSDigest_SignMessage(msg, &end, authInfo, 0); // DNSDigest_SignMessage operates on message in network byte order
#if defined(DEBUG) && DEBUG
if (authInfo && end)
{
// If this is a debug build, every time when we sign the response, use the verifying function to ensure that
// both functions work correctly.
DNSDigest_VerifyMessage_Verify(msg, end, authInfo);
}
#endif
if (!end)
{
LogRedact(MDNS_LOG_CATEGORY_DEFAULT, MDNS_LOG_DEFAULT, "mDNSSendDNSMessage: DNSDigest_SignMessage failed");
status = mStatus_NoMemoryErr;
}
else
{
// Send the packet on the wire
if (!tcpSrc)
status = mDNSPlatformSendUDP(m, msg, end, InterfaceID, udpSrc, dst, dstport, useBackgroundTrafficClass);
else
{
mDNSu16 msglen = (mDNSu16)(end - (mDNSu8 *)msg);
mDNSu8 lenbuf[2] = { (mDNSu8)(msglen >> 8), (mDNSu8)(msglen & 0xFF) };
char *buf;
long nsent;
// Try to send them in one packet if we can allocate enough memory
buf = (char *) mDNSPlatformMemAllocate(msglen + 2);
if (buf)
{
buf[0] = lenbuf[0];
buf[1] = lenbuf[1];
mDNSPlatformMemCopy(buf+2, msg, msglen);
nsent = mDNSPlatformWriteTCP(tcpSrc, buf, msglen+2);
if (nsent != (msglen + 2))
{
LogRedact(MDNS_LOG_CATEGORY_DEFAULT, MDNS_LOG_DEFAULT, "mDNSSendDNSMessage: write message failed %ld/%d", nsent, msglen);
status = mStatus_ConnFailed;
}
mDNSPlatformMemFree(buf);
}
else
{
nsent = mDNSPlatformWriteTCP(tcpSrc, (char*)lenbuf, 2);
if (nsent != 2)
{
LogRedact(MDNS_LOG_CATEGORY_DEFAULT, MDNS_LOG_DEFAULT, "mDNSSendDNSMessage: write msg length failed %ld/%d", nsent, 2);
status = mStatus_ConnFailed;
}
else
{
nsent = mDNSPlatformWriteTCP(tcpSrc, (char *)msg, msglen);
if (nsent != msglen)
{
LogRedact(MDNS_LOG_CATEGORY_DEFAULT, MDNS_LOG_DEFAULT, "mDNSSendDNSMessage: write msg body failed %ld/%d", nsent, msglen);
status = mStatus_ConnFailed;
}
}
}
}
}
// Swap the integer values back the way they were (remember that numAdditionals may have been changed by putHINFO and/or SignMessage)
SwapDNSHeaderBytes(msg);
char *transport = "UDP";
mDNSIPPort portNumber = udpSrc ? udpSrc->port : MulticastDNSPort;
if (tcpSrc)
{
if (tcpSrc->flags)
transport = "TLS";
else
transport = "TCP";
portNumber = tcpSrc->port;
}
DumpPacket(status, mDNStrue, transport, mDNSNULL, portNumber, dst, dstport, msg, end, InterfaceID);
// put the number of additionals back the way it was
msg->h.numAdditionals = numAdditionals;
return(status);
}
// ***************************************************************************
// MARK: - DNSQuestion Functions
#if MDNSRESPONDER_SUPPORTS(APPLE, LOG_PRIVACY_LEVEL)
mDNSBool DNSQuestionNeedsSensitiveLogging(const DNSQuestion *const q)
{
return is_apple_internal_build() && (q->logPrivacyLevel == dnssd_log_privacy_level_private);
}
#endif
#if MDNSRESPONDER_SUPPORTS(APPLE, RUNTIME_MDNS_METRICS)
mDNSBool DNSQuestionCollectsMDNSMetric(const DNSQuestion *const q)
{
return (!q->DuplicateOf && mDNSOpaque16IsZero(q->TargetQID));
}
#endif
#if MDNSRESPONDER_SUPPORTS(APPLE, TERMINUS_ASSISTED_UNICAST_DISCOVERY)
mDNSlocal mDNSBool DNSQuestionUsesAWDL(const DNSQuestion *const q)
{
if (q->InterfaceID == mDNSInterface_Any)
{
return ((q->flags & kDNSServiceFlagsIncludeAWDL) != 0);
}
else
{
return mDNSPlatformInterfaceIsAWDL(q->InterfaceID);
}
}
mDNSBool DNSQuestionIsEligibleForMDNSAlternativeService(const DNSQuestion *const q)
{
// 0. The system is not in a demo mode where mDNS traffic is ensured to be lossless in a wired connection.
// 1. The question must be an mDNS question.
// 2. The question cannot enable resolution over AWDL.
// (because the resolution over mDNS alternative service is mutual exclusive with the resolution over AWDL)
return (!is_airplay_demo_mode_enabled() && mDNSOpaque16IsZero(q->TargetQID) && !DNSQuestionUsesAWDL(q));
}
mDNSBool DNSQuestionRequestsMDNSAlternativeService(const DNSQuestion *const q)
{
return (!mDNSOpaque16IsZero(q->TargetQID) && !Question_uDNS(q));
}
mDNSBool DNSQuestionUsesMDNSAlternativeService(const DNSQuestion *const q)
{
return q->dnsservice && mdns_dns_service_is_mdns_alternative(q->dnsservice);
}
#endif
// ***************************************************************************
// MARK: - RR List Management & Task Management
mDNSexport void mDNS_VerifyLockState(const char *const operation, const mDNSBool checkIfLockHeld,
const mDNSu32 mDNS_busy, const mDNSu32 mDNS_reentrancy, const char *const functionName, const mDNSu32 lineNumber)
{
#if MDNSRESPONDER_SUPPORTS(APPLE, OS_UNFAIR_LOCK)
static os_unfair_lock logLock = OS_UNFAIR_LOCK_INIT;
#endif
static const char *lastLockOperator = mDNSNULL; // The name of the function that succeeded in doing lock operation last time.
static mDNSu32 lineNumberlastLockOperator = 0; // The line number in the source code when this function gets called last time.
#define CRASH_ON_LOCK_ERROR 0
#if (CRASH_ON_LOCK_ERROR)
// When CRASH_ON_LOCK_ERROR is set to 1, if we encounter lock error, we will make mDNSResponder crash immediately
// to let the bug to be identified easily.
mDNSBool lockErrorEncountered = mDNSfalse;
#endif
if (checkIfLockHeld)
{
// If the lock is held by the caller, then the number of times that the lock has been grabbed should be one more
// than the number of times that the lock has been dropped, so that only one lock is currently being held.
if (mDNS_busy > mDNS_reentrancy + 1)
{
LogRedact(MDNS_LOG_CATEGORY_DEFAULT, MDNS_LOG_FAULT,
"Lock failure: Check Lock, lock was grabbed by multiple callers - "
"caller: " PUB_S " at line %u, last successful lock holder: " PUB_S " at line %u, "
"mDNS_busy (%u) != mDNS_reentrancy (%u).", functionName, lineNumber, lastLockOperator,
lineNumberlastLockOperator, mDNS_busy, mDNS_reentrancy);
#if (CRASH_ON_LOCK_ERROR)
lockErrorEncountered = mDNStrue;
#endif
}
else if (mDNS_busy < mDNS_reentrancy + 1)
{
LogRedact(MDNS_LOG_CATEGORY_DEFAULT, MDNS_LOG_FAULT,
"Lock failure: Check Lock, last lock dropper dropped the lock before grabbing it - "
"caller: " PUB_S " at line %u, last lock dropper: " PUB_S " at line %u, "
"mDNS_busy (%u) != mDNS_reentrancy (%u).", functionName, lineNumber, lastLockOperator,
lineNumberlastLockOperator, mDNS_busy, mDNS_reentrancy);
#if (CRASH_ON_LOCK_ERROR)
lockErrorEncountered = mDNStrue;
#endif
}
}
else
{
// In non-critical section:
// The number of times that the lock has been grabbed should be equal to the number of times that the lock has
// been dropped, which means, no one is currently holding the real lock.
if (mDNS_busy == mDNS_reentrancy)
{
switch (operation[0])
{
case 'L': // "Lock" (it is paired with "Unlock")
case 'D': // "Drop Lock" (it is paired with "Reclaim Lock")
// Add new lock state, and we need to remember who succeeds in doing the operation because it might
// lead to invalid lock state.
#if MDNSRESPONDER_SUPPORTS(APPLE, OS_UNFAIR_LOCK)
os_unfair_lock_lock(&logLock);
#endif
lastLockOperator = functionName;
lineNumberlastLockOperator = lineNumber;
#if MDNSRESPONDER_SUPPORTS(APPLE, OS_UNFAIR_LOCK)
os_unfair_lock_unlock(&logLock);
#endif
break;
case 'U': // "Unlock"
case 'R': // "Reclaim Lock"
// Remove the previous lock state, and we can remove the name and the line number that has been
// saved.
#if MDNSRESPONDER_SUPPORTS(APPLE, OS_UNFAIR_LOCK)
os_unfair_lock_lock(&logLock);
#endif
lastLockOperator = mDNSNULL;
lineNumberlastLockOperator = 0;
#if MDNSRESPONDER_SUPPORTS(APPLE, OS_UNFAIR_LOCK)
os_unfair_lock_unlock(&logLock);
#endif
case 'C': // "Check Lock"
// "Check Lock" operation will never change the lock state, so no need to take a note for that.
break;
default:
LogRedact(MDNS_LOG_CATEGORY_DEFAULT, MDNS_LOG_FAULT, "Invalid lock operation - " PUB_S, operation);
break;
}
}
else if (mDNS_busy > mDNS_reentrancy)
{
// If mDNS_busy is greater than mDNS_reentrancy, there is someone who has grabbed the lock. This is invalid
// in a critical section.
LogRedact(MDNS_LOG_CATEGORY_DEFAULT, MDNS_LOG_FAULT,
"Lock failure: " PUB_S ", last lock holder still holds the lock - "
"caller: " PUB_S " at line %u, last successful lock holder: " PUB_S " at line %u, "
"mDNS_busy (%u) != mDNS_reentrancy (%u).", operation, functionName, lineNumber, lastLockOperator,
lineNumberlastLockOperator, mDNS_busy, mDNS_reentrancy);
#if (CRASH_ON_LOCK_ERROR)
lockErrorEncountered = mDNStrue;
#endif
}
else // m->mDNS_busy < m->mDNS_reentrancy
{
// If mDNS_busy is less than mDNS_reentrancy, something bad happens, because no one should drop the lock
// before grabbing it successfully. This should never heppen.
LogRedact(MDNS_LOG_CATEGORY_DEFAULT, MDNS_LOG_FAULT,
"Lock failure: " PUB_S ", last lock dropper dropped the lock before grabbing it - "
"caller: " PUB_S " at line %u, last lock dropper: " PUB_S " at line %u, "
"mDNS_busy (%u) != mDNS_reentrancy (%u).", operation, functionName, lineNumber, lastLockOperator,
lineNumberlastLockOperator, mDNS_busy, mDNS_reentrancy);
#if (CRASH_ON_LOCK_ERROR)
lockErrorEncountered = mDNStrue;
#endif
}
}
#if (CRASH_ON_LOCK_ERROR)
if (lockErrorEncountered)
{
LogRedact(MDNS_LOG_CATEGORY_DEFAULT, MDNS_LOG_ERROR,
"Encounter lock error, make mDNSResponder crash immediately.");
assert(0);
}
#endif
}
mDNSexport void mDNS_Lock_(mDNS *const m, const char *const functionName, const mDNSu32 lineNumber)
{
// MUST grab the platform lock FIRST!
mDNSPlatformLock(m);
// Normally, mDNS_reentrancy is zero and so is mDNS_busy
// However, when we call a client callback mDNS_busy is one, and we increment mDNS_reentrancy too
// If that client callback does mDNS API calls, mDNS_reentrancy and mDNS_busy will both be one
// If mDNS_busy != mDNS_reentrancy that's a bad sign
mDNS_VerifyLockState("Lock", mDNSfalse, m->mDNS_busy, m->mDNS_reentrancy, functionName, lineNumber);
// If this is an initial entry into the mDNSCore code, set m->timenow
// else, if this is a re-entrant entry into the mDNSCore code, m->timenow should already be set
if (m->mDNS_busy == 0)
{
if (m->timenow)
{
LogRedact(MDNS_LOG_CATEGORY_DEFAULT, MDNS_LOG_DEFAULT, PUB_S ": mDNS_Lock: m->timenow already set (%u/%u)",
functionName, m->timenow, mDNS_TimeNow_NoLock(m));
}
m->timenow = mDNS_TimeNow_NoLock(m);
if (m->timenow == 0) m->timenow = 1;
}
else if (m->timenow == 0)
{
LogRedact(MDNS_LOG_CATEGORY_DEFAULT, MDNS_LOG_DEFAULT,
PUB_S ": mDNS_Lock: m->mDNS_busy is %u but m->timenow not set", functionName, m->mDNS_busy);
m->timenow = mDNS_TimeNow_NoLock(m);
if (m->timenow == 0) m->timenow = 1;
}
if (m->timenow_last - m->timenow > 0)
{
m->timenow_adjust += m->timenow_last - m->timenow;
LogRedact(MDNS_LOG_CATEGORY_DEFAULT, MDNS_LOG_DEFAULT,
PUB_S ": mDNSPlatformRawTime went backwards by %d ticks; setting correction factor to %d",
functionName, m->timenow_last - m->timenow, m->timenow_adjust);
m->timenow = m->timenow_last;
}
m->timenow_last = m->timenow;
// Increment mDNS_busy so we'll recognise re-entrant calls
m->mDNS_busy++;
m->mDNS_Lock_functionname = functionName;
m->mDNS_Lock_lineno = lineNumber;
}
mDNSlocal AuthRecord *AnyLocalRecordReady(const mDNS *const m)
{
AuthRecord *rr;
for (rr = m->NewLocalRecords; rr; rr = rr->next)
if (LocalRecordReady(rr)) return rr;
return mDNSNULL;
}
mDNSlocal mDNSs32 GetNextScheduledEvent(const mDNS *const m)
{
mDNSs32 e = m->timenow + FutureTime;
if (m->mDNSPlatformStatus != mStatus_NoError) return(e);
if (m->NewQuestions)
{
if (m->NewQuestions->DelayAnswering) e = m->NewQuestions->DelayAnswering;
else return(m->timenow);
}
if (m->NewLocalOnlyQuestions) return(m->timenow);
if (m->NewLocalRecords && AnyLocalRecordReady(m)) return(m->timenow);
if (m->NewLocalOnlyRecords) return(m->timenow);
if (m->SPSProxyListChanged) return(m->timenow);
if (m->LocalRemoveEvents) return(m->timenow);
#ifndef UNICAST_DISABLED
if (e - m->NextuDNSEvent > 0) e = m->NextuDNSEvent;
if (e - m->NextScheduledNATOp > 0) e = m->NextScheduledNATOp;
if (m->NextSRVUpdate && e - m->NextSRVUpdate > 0) e = m->NextSRVUpdate;
#endif
if (e - m->NextCacheCheck > 0) e = m->NextCacheCheck;
if (e - m->NextScheduledSPS > 0) e = m->NextScheduledSPS;
if (e - m->NextScheduledKA > 0) e = m->NextScheduledKA;
#if MDNSRESPONDER_SUPPORTS(APPLE, BONJOUR_ON_DEMAND)
if (m->NextBonjourDisableTime && (e - m->NextBonjourDisableTime > 0)) e = m->NextBonjourDisableTime;
#endif
// Check if it is time to stop domain enumeration.
for (const DomainEnumerationOp *op = m->domainsToDoEnumeration; op != mDNSNULL; op = op->next)
{
// Iterate over all types of domain enumeration.
for (mDNSu32 type = 0; type < mDNS_DomainTypeMaxCount; type++)
{
if (op->enumerations[type] == mDNSNULL)
{
continue;
}
// Only check the domain enumeration that starts the stopping process.
if (op->enumerations[type]->state != DomainEnumerationState_StopInProgress)
{
continue;
}
if (e - op->enumerations[type]->nextStopTime > 0)
{
e = op->enumerations[type]->nextStopTime;
}
}
}
#if MDNSRESPONDER_SUPPORTS(COMMON, LOCAL_DNS_RESOLVER_DISCOVERY)
const mDNSs32 nextResolverDiscoveryEvent = ResolverDiscovery_GetNextScheduledEvent();
if (nextResolverDiscoveryEvent && (e - nextResolverDiscoveryEvent > 0)) e = nextResolverDiscoveryEvent;
#endif
// NextScheduledSPRetry only valid when DelaySleep not set
if (!m->DelaySleep && m->SleepLimit && e - m->NextScheduledSPRetry > 0) e = m->NextScheduledSPRetry;
if (m->DelaySleep && e - m->DelaySleep > 0) e = m->DelaySleep;
if (m->SuppressQueries)
{
if (e - m->SuppressQueries > 0) e = m->SuppressQueries;
}
else
{
if (e - m->NextScheduledQuery > 0) e = m->NextScheduledQuery;
if (e - m->NextScheduledProbe > 0) e = m->NextScheduledProbe;
}
if (m->SuppressResponses)
{
if (e - m->SuppressResponses > 0) e = m->SuppressResponses;
}
else
{
if (e - m->NextScheduledResponse > 0) e = m->NextScheduledResponse;
}
if (e - m->NextScheduledStopTime > 0) e = m->NextScheduledStopTime;
if (m->NextBLEServiceTime && (e - m->NextBLEServiceTime > 0)) e = m->NextBLEServiceTime;
#if MDNSRESPONDER_SUPPORTS(APPLE, DNSSECv2)
if (m->NextUpdateDNSSECValidatedCache && (e - m->NextUpdateDNSSECValidatedCache > 0))
{
e = m->NextUpdateDNSSECValidatedCache;
}
#endif
#if MDNSRESPONDER_SUPPORTS(APPLE, RUNTIME_MDNS_METRICS)
if (m->NextMDNSResponseDelayReport && (e - m->NextMDNSResponseDelayReport > 0))
{
e = m->NextMDNSResponseDelayReport;
}
#endif
return(e);
}
#define LogTSE TSE++,LogMsg
mDNSexport void ShowTaskSchedulingError(mDNS *const m)
{
int TSE = 0;
AuthRecord *rr;
mDNS_Lock(m);
LogMsg("Task Scheduling Error: *** Continuously busy for more than a second");
// Note: To accurately diagnose *why* we're busy, the debugging code here needs to mirror the logic in GetNextScheduledEvent above
if (m->NewQuestions && (!m->NewQuestions->DelayAnswering || m->timenow - m->NewQuestions->DelayAnswering >= 0))
LogTSE("Task Scheduling Error: NewQuestion %##s (%s)",
m->NewQuestions->qname.c, DNSTypeName(m->NewQuestions->qtype));
if (m->NewLocalOnlyQuestions)
LogTSE("Task Scheduling Error: NewLocalOnlyQuestions %##s (%s)",
m->NewLocalOnlyQuestions->qname.c, DNSTypeName(m->NewLocalOnlyQuestions->qtype));
if (m->NewLocalRecords)
{
rr = AnyLocalRecordReady(m);
if (rr) LogTSE("Task Scheduling Error: NewLocalRecords %s", ARDisplayString(m, rr));
}
if (m->NewLocalOnlyRecords) LogTSE("Task Scheduling Error: NewLocalOnlyRecords");
if (m->SPSProxyListChanged) LogTSE("Task Scheduling Error: SPSProxyListChanged");
if (m->LocalRemoveEvents) LogTSE("Task Scheduling Error: LocalRemoveEvents");
#ifndef UNICAST_DISABLED
if (m->timenow - m->NextuDNSEvent >= 0)
LogTSE("Task Scheduling Error: m->NextuDNSEvent %d", m->timenow - m->NextuDNSEvent);
if (m->timenow - m->NextScheduledNATOp >= 0)
LogTSE("Task Scheduling Error: m->NextScheduledNATOp %d", m->timenow - m->NextScheduledNATOp);
if (m->NextSRVUpdate && m->timenow - m->NextSRVUpdate >= 0)
LogTSE("Task Scheduling Error: m->NextSRVUpdate %d", m->timenow - m->NextSRVUpdate);
#endif
if (m->timenow - m->NextCacheCheck >= 0)
LogTSE("Task Scheduling Error: m->NextCacheCheck %d", m->timenow - m->NextCacheCheck);
if (m->timenow - m->NextScheduledSPS >= 0)
LogTSE("Task Scheduling Error: m->NextScheduledSPS %d", m->timenow - m->NextScheduledSPS);
if (m->timenow - m->NextScheduledKA >= 0)
LogTSE("Task Scheduling Error: m->NextScheduledKA %d", m->timenow - m->NextScheduledKA);
if (!m->DelaySleep && m->SleepLimit && m->timenow - m->NextScheduledSPRetry >= 0)
LogTSE("Task Scheduling Error: m->NextScheduledSPRetry %d", m->timenow - m->NextScheduledSPRetry);
if (m->DelaySleep && m->timenow - m->DelaySleep >= 0)
LogTSE("Task Scheduling Error: m->DelaySleep %d", m->timenow - m->DelaySleep);
if (m->SuppressQueries && m->timenow - m->SuppressQueries >= 0)
LogTSE("Task Scheduling Error: m->SuppressQueries %d", m->timenow - m->SuppressQueries);
if (m->SuppressResponses && m->timenow - m->SuppressResponses >= 0)
LogTSE("Task Scheduling Error: m->SuppressResponses %d", m->timenow - m->SuppressResponses);
if (m->timenow - m->NextScheduledQuery >= 0)
LogTSE("Task Scheduling Error: m->NextScheduledQuery %d", m->timenow - m->NextScheduledQuery);
if (m->timenow - m->NextScheduledProbe >= 0)
LogTSE("Task Scheduling Error: m->NextScheduledProbe %d", m->timenow - m->NextScheduledProbe);
if (m->timenow - m->NextScheduledResponse >= 0)
LogTSE("Task Scheduling Error: m->NextScheduledResponse %d", m->timenow - m->NextScheduledResponse);
if (m->timenow - m->NextScheduledStopTime >= 0)
LogTSE("Task Scheduling Error: m->NextScheduledStopTime %d", m->timenow - m->NextScheduledStopTime);
if (m->timenow - m->NextScheduledEvent >= 0)
LogTSE("Task Scheduling Error: m->NextScheduledEvent %d", m->timenow - m->NextScheduledEvent);
if (m->NetworkChanged && m->timenow - m->NetworkChanged >= 0)
LogTSE("Task Scheduling Error: NetworkChanged %d", m->timenow - m->NetworkChanged);
if (!TSE) LogMsg("Task Scheduling Error: *** No likely causes identified");
else LogMsg("Task Scheduling Error: *** %d potential cause%s identified (significant only if the same cause consistently appears)", TSE, TSE > 1 ? "s" : "");
mDNS_Unlock(m);
}
mDNSexport void mDNS_Unlock_(mDNS *const m, const char *const functionName, const mDNSu32 lineNumber)
{
// Decrement mDNS_busy
m->mDNS_busy--;
// Check for locking failures
mDNS_VerifyLockState("Unlock", mDNSfalse, m->mDNS_busy, m->mDNS_reentrancy, functionName, lineNumber);
// If this is a final exit from the mDNSCore code, set m->NextScheduledEvent and clear m->timenow
if (m->mDNS_busy == 0)
{
m->NextScheduledEvent = GetNextScheduledEvent(m);
if (m->timenow == 0)
{
LogRedact(MDNS_LOG_CATEGORY_DEFAULT, MDNS_LOG_ERROR, PUB_S ": mDNS_Unlock: ERROR! m->timenow aready zero",
functionName);
}
m->timenow = 0;
}
// MUST release the platform lock LAST!
mDNSPlatformUnlock(m);
}
// ***************************************************************************
// MARK: - Specialized mDNS version of vsnprintf
static const struct mDNSprintf_format
{
unsigned leftJustify : 1;
unsigned forceSign : 1;
unsigned zeroPad : 1;
unsigned havePrecision : 1;
unsigned hSize : 1;
unsigned lSize : 1;
char altForm;
char sign; // +, - or space
unsigned int fieldWidth;
unsigned int precision;
} mDNSprintf_format_default = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
#define kHexDigitsLowercase "0123456789abcdef"
#define kHexDigitsUppercase "0123456789ABCDEF";
mDNSexport mDNSu32 mDNS_vsnprintf(char *sbuffer, mDNSu32 buflen, const char *fmt, va_list arg)
{
mDNSu32 nwritten = 0;
int c;
if (buflen == 0) return(0);
buflen--; // Pre-reserve one space in the buffer for the terminating null
if (buflen == 0) goto exit;
for (c = *fmt; c != '\0'; c = (c != '\0') ? *++fmt : c)
{
unsigned long n;
int hexdump = mDNSfalse;
if (c != '%')
{
*sbuffer++ = (char)c;
if (++nwritten >= buflen) goto exit;
}
else
{
unsigned int i=0, j;
// The mDNS Vsprintf Argument Conversion Buffer is used as a temporary holding area for
// generating decimal numbers, hexdecimal numbers, IP addresses, domain name strings, etc.
// The size needs to be enough for a 256-byte domain name plus some error text.
#define mDNS_VACB_Size 300
char mDNS_VACB[mDNS_VACB_Size];
#define mDNS_VACB_Lim (&mDNS_VACB[mDNS_VACB_Size])
#define mDNS_VACB_Remain(s) ((mDNSu32)(mDNS_VACB_Lim - s))
char *s = mDNS_VACB_Lim, *digits;
struct mDNSprintf_format F = mDNSprintf_format_default;
while (1) // decode flags
{
c = *++fmt;
if (c == '-') F.leftJustify = 1;
else if (c == '+') F.forceSign = 1;
else if (c == ' ') F.sign = ' ';
else if (c == '#') F.altForm++;
else if (c == '0') F.zeroPad = 1;
else break;
}
if (c == '*') // decode field width
{
int f = va_arg(arg, int);
if (f < 0) { f = -f; F.leftJustify = 1; }
F.fieldWidth = (unsigned int)f;
c = *++fmt;
}
else
{
for (; c >= '0' && c <= '9'; c = *++fmt)
F.fieldWidth = (10 * F.fieldWidth) + (c - '0');
}
if (c == '.') // decode precision
{
if ((c = *++fmt) == '*')
{ F.precision = va_arg(arg, unsigned int); c = *++fmt; }
else for (; c >= '0' && c <= '9'; c = *++fmt)
F.precision = (10 * F.precision) + (c - '0');
F.havePrecision = 1;
}
if (F.leftJustify) F.zeroPad = 0;
conv:
switch (c) // perform appropriate conversion
{
case 'h': F.hSize = 1; c = *++fmt; goto conv;
case 'l': // fall through
case 'L': F.lSize = 1; c = *++fmt; goto conv;
case 'd':
case 'i': if (F.lSize) n = (unsigned long)va_arg(arg, long);
else n = (unsigned long)va_arg(arg, int);
if (F.hSize) n = (short) n;
if ((long) n < 0) { n = (unsigned long)-(long)n; F.sign = '-'; }
else if (F.forceSign) F.sign = '+';
goto decimal;
case 'u': if (F.lSize) n = va_arg(arg, unsigned long);
else n = va_arg(arg, unsigned int);
if (F.hSize) n = (unsigned short) n;
F.sign = 0;
goto decimal;
decimal: if (!F.havePrecision)
{
if (F.zeroPad)
{
F.precision = F.fieldWidth;
if (F.sign) --F.precision;
}
if (F.precision < 1) F.precision = 1;
}
if (F.precision > mDNS_VACB_Size - 1)
F.precision = mDNS_VACB_Size - 1;
for (i = 0; n; n /= 10, i++) *--s = (char)(n % 10 + '0');
for (; i < F.precision; i++) *--s = '0';
if (F.sign) { *--s = F.sign; i++; }
break;
case 'o': if (F.lSize) n = va_arg(arg, unsigned long);
else n = va_arg(arg, unsigned int);
if (F.hSize) n = (unsigned short) n;
if (!F.havePrecision)
{
if (F.zeroPad) F.precision = F.fieldWidth;
if (F.precision < 1) F.precision = 1;
}
if (F.precision > mDNS_VACB_Size - 1)
F.precision = mDNS_VACB_Size - 1;
for (i = 0; n; n /= 8, i++) *--s = (char)(n % 8 + '0');
if (F.altForm && i && *s != '0') { *--s = '0'; i++; }
for (; i < F.precision; i++) *--s = '0';
break;
case 'a': {
unsigned char *a = va_arg(arg, unsigned char *);
if (!a) { static char emsg[] = "<<NULL>>"; s = emsg; i = sizeof(emsg)-1; }
else
{
s = mDNS_VACB; // Adjust s to point to the start of the buffer, not the end
if (F.altForm)
{
const mDNSAddr *const ip = (const mDNSAddr *)a;
switch (ip->type)
{
case mDNSAddrType_IPv4: F.precision = 4; a = (unsigned char *)&ip->ip.v4; break;
case mDNSAddrType_IPv6: F.precision = 16; a = (unsigned char *)&ip->ip.v6; break;
default:
if (ip->type == mDNSAddrType_None)
{
i = mDNS_snprintf(mDNS_VACB, sizeof(mDNS_VACB), "<<UNSPECIFIED IP ADDRESS>>");
}
else
{
i = mDNS_snprintf(mDNS_VACB, sizeof(mDNS_VACB),
"<<ERROR: %%#a used with unsupported type: %d>>", ip->type);
}
F.precision = 0;
break;
}
}
if (!F.altForm || (F.precision != 0))
{
switch (F.precision)
{
case 4: i = mDNS_snprintf(mDNS_VACB, sizeof(mDNS_VACB), "%d.%d.%d.%d",
a[0], a[1], a[2], a[3]); break;
case 6: i = mDNS_snprintf(mDNS_VACB, sizeof(mDNS_VACB), "%02X:%02X:%02X:%02X:%02X:%02X",
a[0], a[1], a[2], a[3], a[4], a[5]); break;
case 16: {
// Print IPv6 addresses according to RFC 5952, A Recommendation for IPv6 Address Text
// Representation. See <https://tools.ietf.org/html/rfc5952>.
int idx, runLen = 0, runStart = 0, maxRunLen = 0, maxRunStart = 0, maxRunEnd;
// Find the leftmost longest run of consecutive zero hextets.
for (idx = 0; idx < 8; ++idx)
{
const unsigned int hextet = (a[idx * 2] << 8) | a[(idx * 2) + 1];
if (hextet == 0)
{
if (runLen++ == 0) runStart = idx;
if (runLen > maxRunLen)
{
maxRunStart = runStart;
maxRunLen = runLen;
}
}
else
{
// If the number of remaining hextets is less than or equal to the length of the longest
// run so far, then we've found the leftmost longest run.
if ((8 - (idx + 1)) <= maxRunLen) break;
runLen = 0;
}
}
// Compress the leftmost longest run of two or more consecutive zero hextets as "::".
// For each reminaing hextet, suppress zeros leading up to the least-significant nibble, which
// is always written, even if it's zero. Because of this requirement, it's easier to write the
// IPv6 address in reverse. Also, write a colon separator before each hextet except for the
// first one.
s = mDNS_VACB_Lim;
maxRunEnd = (maxRunLen >= 2) ? (maxRunStart + maxRunLen - 1) : -1;
for (idx = 7; idx >= 0; --idx)
{
if (idx == maxRunEnd)
{
if (idx == 7) *--s = ':';
idx = maxRunStart;
*--s = ':';
}
else
{
unsigned int hextet = (a[idx * 2] << 8) | a[(idx * 2) + 1];
do {
*--s = kHexDigitsLowercase[hextet % 16];
hextet /= 16;
} while (hextet);
if (idx > 0) *--s = ':';
}
}
i = (unsigned int)(mDNS_VACB_Lim - s);
}
break;
default: i = mDNS_snprintf(mDNS_VACB, sizeof(mDNS_VACB), "%s", "<< ERROR: Must specify"
" address size (i.e. %.4a=IPv4, %.6a=Ethernet, %.16a=IPv6) >>"); break;
}
}
}
}
break;
case 'p': F.havePrecision = F.lSize = 1;
F.precision = sizeof(void*) * 2; // 8 characters on 32-bit; 16 characters on 64-bit
fallthrough();
case 'X': digits = kHexDigitsUppercase;
goto hexadecimal;
case 'x': digits = kHexDigitsLowercase;
hexadecimal: if (F.lSize) n = va_arg(arg, unsigned long);
else n = va_arg(arg, unsigned int);
if (F.hSize) n = (unsigned short) n;
if (!F.havePrecision)
{
if (F.zeroPad)
{
F.precision = F.fieldWidth;
if (F.altForm) F.precision -= 2;
}
if (F.precision < 1) F.precision = 1;
}
if (F.precision > mDNS_VACB_Size - 1)
F.precision = mDNS_VACB_Size - 1;
for (i = 0; n; n /= 16, i++) *--s = digits[n % 16];
for (; i < F.precision; i++) *--s = '0';
#ifndef FUZZING // Pascal strings aren't supported for fuzzing
if (F.altForm) { *--s = (char)c; *--s = '0'; i += 2; }
#endif
break;
case 'c': *--s = (char)va_arg(arg, int); i = 1; break;
case 's': s = va_arg(arg, char *);
if (!s) { static char emsg[] = "<<NULL>>"; s = emsg; i = sizeof(emsg)-1; }
else switch (F.altForm)
{
case 0: i=0;
if (!F.havePrecision) // C string
while (s[i]) i++;
else
{
while ((i < F.precision) && s[i]) i++;
// Make sure we don't truncate in the middle of a UTF-8 character
// If last character we got was any kind of UTF-8 multi-byte character,
// then see if we have to back up.
// This is not as easy as the similar checks below, because
// here we can't assume it's safe to examine the *next* byte, so we
// have to confine ourselves to working only backwards in the string.
j = i; // Record where we got to
// Now, back up until we find first non-continuation-char
while (i>0 && (s[i-1] & 0xC0) == 0x80) i--;
// Now s[i-1] is the first non-continuation-char
// and (j-i) is the number of continuation-chars we found
if (i>0 && (s[i-1] & 0xC0) == 0xC0) // If we found a start-char
{
i--; // Tentatively eliminate this start-char as well
// Now (j-i) is the number of characters we're considering eliminating.
// To be legal UTF-8, the start-char must contain (j-i) one-bits,
// followed by a zero bit. If we shift it right by (7-(j-i)) bits
// (with sign extension) then the result has to be 0xFE.
// If this is right, then we reinstate the tentatively eliminated bytes.
if (((j-i) < 7) && (((s[i] >> (7-(j-i))) & 0xFF) == 0xFE)) i = j;
}
}
break;
#ifndef FUZZING // Pascal strings aren't supported for fuzzing
case 1: i = (unsigned char) *s++; break; // Pascal string
#endif
case 2: { // DNS label-sequence name
unsigned char *a = (unsigned char *)s;
s = mDNS_VACB; // Adjust s to point to the start of the buffer, not the end
if (*a == 0) *s++ = '.'; // Special case for root DNS name
while (*a)
{
char buf[63*4+1];
if (*a > 63)
{ s += mDNS_snprintf(s, mDNS_VACB_Remain(s), "<<INVALID LABEL LENGTH %u>>", *a); break; }
if (s + *a >= &mDNS_VACB[254])
{ s += mDNS_snprintf(s, mDNS_VACB_Remain(s), "<<NAME TOO LONG>>"); break; }
// Need to use ConvertDomainLabelToCString to do proper escaping here,
// so it's clear what's a literal dot and what's a label separator
ConvertDomainLabelToCString((domainlabel*)a, buf);
s += mDNS_snprintf(s, mDNS_VACB_Remain(s), "%s.", buf);
a += 1 + *a;
}
i = (mDNSu32)(s - mDNS_VACB);
s = mDNS_VACB; // Reset s back to the start of the buffer
break;
}
default:
break;
}
// Make sure we don't truncate in the middle of a UTF-8 character (see similar comment below)
if (F.havePrecision && i > F.precision)
{ i = F.precision; while (i>0 && (s[i] & 0xC0) == 0x80) i--;}
break;
case 'H': {
s = va_arg(arg, char *);
hexdump = mDNStrue;
}
break;
#ifndef FUZZING
case 'n':
s = va_arg(arg, char *);
if (F.hSize) *(short *) s = (short)nwritten;
else if (F.lSize) *(long *) s = (long)nwritten;
else *(int *) s = (int)nwritten;
continue;
#endif
default: s = mDNS_VACB;
i = mDNS_snprintf(mDNS_VACB, sizeof(mDNS_VACB), "<<UNKNOWN FORMAT CONVERSION CODE %%%c>>", mDNSIsPrintASCII(c) ? c : ' ');
break;
case '%': *sbuffer++ = (char)c;
if (++nwritten >= buflen) goto exit;
break;
}
if (i < F.fieldWidth && !F.leftJustify) // Pad on the left
do {
*sbuffer++ = ' ';
if (++nwritten >= buflen) goto exit;
} while (i < --F.fieldWidth);
if (hexdump)
{
#ifndef FUZZING
char *dst = sbuffer;
const char *const lim = &sbuffer[buflen - nwritten];
if (F.havePrecision)
{
for (i = 0; (i < F.precision) && (dst < lim); i++)
{
const unsigned int b = (unsigned int) *s++;
if (i > 0) *dst++ = ' ';
if (dst < lim) *dst++ = kHexDigitsLowercase[(b >> 4) & 0xF];
if (dst < lim) *dst++ = kHexDigitsLowercase[ b & 0xF];
}
}
i = (unsigned int)(dst - sbuffer);
sbuffer = dst;
#endif
}
else
{
// Make sure we don't truncate in the middle of a UTF-8 character.
// Note: s[i] is the first eliminated character; i.e. the next character *after* the last character of the
// allowed output. If s[i] is a UTF-8 continuation character, then we've cut a unicode character in half,
// so back up 'i' until s[i] is no longer a UTF-8 continuation character. (if the input was proprly
// formed, s[i] will now be the UTF-8 start character of the multi-byte character we just eliminated).
if (i > buflen - nwritten)
{ i = buflen - nwritten; while (i>0 && (s[i] & 0xC0) == 0x80) i--;}
for (j=0; j<i; j++) *sbuffer++ = *s++; // Write the converted result
}
nwritten += i;
if (nwritten >= buflen) goto exit;
for (; i < F.fieldWidth; i++) // Pad on the right
{
*sbuffer++ = ' ';
if (++nwritten >= buflen) goto exit;
}
}
}
exit:
*sbuffer++ = 0;
return(nwritten);
}
mDNSexport mDNSu32 mDNS_snprintf(char *sbuffer, mDNSu32 buflen, const char *fmt, ...)
{
mDNSu32 length;
va_list ptr;
va_start(ptr,fmt);
length = mDNS_vsnprintf(sbuffer, buflen, fmt, ptr);
va_end(ptr);
return(length);
}
#if !MDNSRESPONDER_SUPPORTS(APPLE, QUERIER)
mDNSexport mDNSu32 mDNS_GetNextResolverGroupID(void)
{
static mDNSu32 lastID = 0;
if (++lastID == 0) lastID = 1; // Valid resolver group IDs are non-zero.
return(lastID);
}
#endif
#define kReverseIPv6Domain ((const domainname *) "\x3" "ip6" "\x4" "arpa")
mDNSexport mDNSBool GetReverseIPv6Addr(const domainname *name, mDNSu8 outIPv6[16])
{
const mDNSu8 * ptr;
int i;
mDNSu8 ipv6[16];
// If the name is of the form "x.x.x.x.x.x.x.x.x.x.x.x.x.x.x.x.x.x.x.x.x.x.x.x.x.x.x.x.x.x.x.x.ip6.arpa.", where each x
// is a hex digit, then the sequence of 32 hex digit labels represents the nibbles of an IPv6 address in reverse order.
// See <https://tools.ietf.org/html/rfc3596#section-2.5>.
ptr = name->c;
for (i = 0; i < 32; i++)
{
unsigned int c, nibble;
const int j = 15 - (i / 2);
if (*ptr++ != 1) return (mDNSfalse); // If this label's length is not 1, then fail.
c = *ptr++; // Get label byte.
if ( (c >= '0') && (c <= '9')) nibble = c - '0'; // If it's a hex digit, get its numeric value.
else if ((c >= 'a') && (c <= 'f')) nibble = (c - 'a') + 10;
else if ((c >= 'A') && (c <= 'F')) nibble = (c - 'A') + 10;
else return (mDNSfalse); // Otherwise, fail.
if ((i % 2) == 0)
{
ipv6[j] = (mDNSu8)nibble;
}
else
{
ipv6[j] |= (mDNSu8)(nibble << 4);
}
}
// The rest of the name needs to be "ip6.arpa.". If it isn't, fail.
if (!SameDomainName((const domainname *)ptr, kReverseIPv6Domain)) return (mDNSfalse);
if (outIPv6) mDNSPlatformMemCopy(outIPv6, ipv6, 16);
return (mDNStrue);
}
#endif // !STANDALONE