mDNSCore/DNSCommon.h

   1 /* -*- Mode: C; tab-width: 4 -*-
   2  *
   3  * Copyright (c) 2002-2020 Apple Inc. All rights reserved.
   4  *
   5  * Licensed under the Apache License, Version 2.0 (the "License");
   6  * you may not use this file except in compliance with the License.
   7  * You may obtain a copy of the License at
   8  *
   9  *     http://www.apache.org/licenses/LICENSE-2.0
  10  *
  11  * Unless required by applicable law or agreed to in writing, software
  12  * distributed under the License is distributed on an "AS IS" BASIS,
  13  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14  * See the License for the specific language governing permissions and
  15  * limitations under the License.
  16  */
  17
  18 #ifndef __DNSCOMMON_H_
  19 #define __DNSCOMMON_H_
  20
  21 #include "mDNSEmbeddedAPI.h"
  22
  23 #ifdef  __cplusplus
  24 extern "C" {
  25 #endif
  26
  27 //*************************************************************************************************************
  28 // Macros
  29
  30 // Note: The C preprocessor stringify operator ('#') makes a string from its argument, without macro expansion
  31 // e.g. If "version" is #define'd to be "4", then STRINGIFY_AWE(version) will return the string "version", not "4"
  32 // To expand "version" to its value before making the string, use STRINGIFY(version) instead
  33 #define STRINGIFY_ARGUMENT_WITHOUT_EXPANSION(s) # s
  34 #define STRINGIFY(s) STRINGIFY_ARGUMENT_WITHOUT_EXPANSION(s)
  35
  36 // ***************************************************************************
  37 #if COMPILER_LIKES_PRAGMA_MARK
  38 #pragma mark - DNS Protocol Constants
  39 #endif
  40
  41 typedef enum
  42 {
  43     kDNSFlag0_QR_Mask        = 0x80,    // Query or response?
  44     kDNSFlag0_QR_Query       = 0x00,
  45     kDNSFlag0_QR_Response    = 0x80,
  46
  47     kDNSFlag0_OP_Mask        = 0xF << 3, // Operation type
  48     kDNSFlag0_OP_StdQuery    = 0x0 << 3,
  49     kDNSFlag0_OP_Iquery      = 0x1 << 3,
  50     kDNSFlag0_OP_Status      = 0x2 << 3,
  51     kDNSFlag0_OP_Unused3     = 0x3 << 3,
  52     kDNSFlag0_OP_Notify      = 0x4 << 3,
  53     kDNSFlag0_OP_Update      = 0x5 << 3,
  54     kDNSFlag0_OP_DSO         = 0x6 << 3,
  55
  56     kDNSFlag0_QROP_Mask   = kDNSFlag0_QR_Mask | kDNSFlag0_OP_Mask,
  57
  58     kDNSFlag0_AA          = 0x04,       // Authoritative Answer?
  59     kDNSFlag0_TC          = 0x02,       // Truncated?
  60     kDNSFlag0_RD          = 0x01,       // Recursion Desired?
  61     kDNSFlag1_RA          = 0x80,       // Recursion Available?
  62
  63     kDNSFlag1_Zero        = 0x40,       // Reserved; must be zero
  64     kDNSFlag1_AD          = 0x20,       // Authentic Data [RFC 2535]
  65     kDNSFlag1_CD          = 0x10,       // Checking Disabled [RFC 2535]
  66
  67     kDNSFlag1_RC_Mask     = 0x0F,       // Response code
  68     kDNSFlag1_RC_NoErr    = 0x00,
  69     kDNSFlag1_RC_FormErr  = 0x01,
  70     kDNSFlag1_RC_ServFail = 0x02,
  71     kDNSFlag1_RC_NXDomain = 0x03,
  72     kDNSFlag1_RC_NotImpl  = 0x04,
  73     kDNSFlag1_RC_Refused  = 0x05,
  74     kDNSFlag1_RC_YXDomain = 0x06,
  75     kDNSFlag1_RC_YXRRSet  = 0x07,
  76     kDNSFlag1_RC_NXRRSet  = 0x08,
  77     kDNSFlag1_RC_NotAuth  = 0x09,
  78     kDNSFlag1_RC_NotZone  = 0x0A,
  79         kDNSFlag1_RC_DSOTypeNI = 0x0B
  80 } DNS_Flags;
  81
  82 typedef enum
  83 {
  84     TSIG_ErrBadSig  = 16,
  85     TSIG_ErrBadKey  = 17,
  86     TSIG_ErrBadTime = 18
  87 } TSIG_ErrorCode;
  88
  89
  90 // ***************************************************************************
  91 #if COMPILER_LIKES_PRAGMA_MARK
  92 #pragma mark -
  93 #pragma mark - General Utility Functions
  94 #endif
  95
  96 extern NetworkInterfaceInfo *GetFirstActiveInterface(NetworkInterfaceInfo *intf);
  97 extern mDNSInterfaceID GetNextActiveInterfaceID(const NetworkInterfaceInfo *intf);
  98
  99 extern mDNSu32 mDNSRandom(mDNSu32 max);     // Returns pseudo-random result from zero to max inclusive
 100
 101 #if !MDNSRESPONDER_SUPPORTS(APPLE, QUERIER)
 102 extern mDNSu32 mDNS_GetNextResolverGroupID(void);
 103 #endif
 104
 105 // ***************************************************************************
 106 #if COMPILER_LIKES_PRAGMA_MARK
 107 #pragma mark -
 108 #pragma mark - Domain Name Utility Functions
 109 #endif
 110
 111 #define mDNSSubTypeLabel   "\x04_sub"
 112
 113 #define mDNSIsDigit(X)     ((X) >= '0' && (X) <= '9')
 114 #define mDNSIsUpperCase(X) ((X) >= 'A' && (X) <= 'Z')
 115 #define mDNSIsLowerCase(X) ((X) >= 'a' && (X) <= 'z')
 116 #define mDNSIsLetter(X)    (mDNSIsUpperCase(X) || mDNSIsLowerCase(X))
 117
 118 // We believe we have adequate safeguards to protect against cache poisoning.
 119 // In the event that someone does find a workable cache poisoning attack, we want to limit the lifetime of the poisoned entry.
 120 // We set the maximum allowable TTL to one hour.
 121 // With the 25% correction factor to avoid the DNS Zeno's paradox bug, that gives us an actual maximum lifetime of 75 minutes.
 122
 123 #define mDNSMaximumMulticastTTLSeconds  (mDNSu32)4500
 124 #define mDNSMaximumUnicastTTLSeconds    (mDNSu32)3600
 125
 126 #define mDNSValidHostChar(X, notfirst, notlast) (mDNSIsLetter(X) || mDNSIsDigit(X) || ((notfirst) && (notlast) && (X) == '-') )
 127
 128 extern mDNSu16 CompressedDomainNameLength(const domainname *const name, const domainname *parent);
 129 extern int CountLabels(const domainname *d);
 130 extern const domainname *SkipLeadingLabels(const domainname *d, int skip);
 131
 132 extern mDNSu32 TruncateUTF8ToLength(mDNSu8 *string, mDNSu32 length, mDNSu32 max);
 133 extern mDNSBool LabelContainsSuffix(const domainlabel *const name, const mDNSBool RichText);
 134 extern mDNSu32 RemoveLabelSuffix(domainlabel *name, mDNSBool RichText);
 135 extern void AppendLabelSuffix(domainlabel *const name, mDNSu32 val, const mDNSBool RichText);
 136 #define ValidateDomainName(N) (DomainNameLength(N) <= MAX_DOMAIN_NAME)
 137
 138 // ***************************************************************************
 139 #if COMPILER_LIKES_PRAGMA_MARK
 140 #pragma mark -
 141 #pragma mark - Resource Record Utility Functions
 142 #endif
 143
 144 // IdenticalResourceRecord returns true if two resources records have
 145 // the same name, type, class, and identical rdata (InterfaceID and TTL may differ)
 146
 147 // IdenticalSameNameRecord is the same, except it skips the expensive SameDomainName() check,
 148 // which is at its most expensive and least useful in cases where we know in advance that the names match
 149
 150 // Note: The dominant use of IdenticalResourceRecord is from ProcessQuery(), handling known-answer lists. In this case
 151 // it's common to have a whole bunch or records with exactly the same name (e.g. "_http._tcp.local") but different RDATA.
 152 // The SameDomainName() check is expensive when the names match, and in this case *all* the names match, so we
 153 // used to waste a lot of CPU time verifying that the names match, only then to find that the RDATA is different.
 154 // We observed mDNSResponder spending 30% of its total CPU time on this single task alone.
 155 // By swapping the checks so that we check the RDATA first, we can quickly detect when it's different
 156 // (99% of the time) and then bail out before we waste time on the expensive SameDomainName() check.
 157
 158 #define IdenticalResourceRecord(r1,r2) ( \
 159         (r1)->rrtype    == (r2)->rrtype      && \
 160         (r1)->rrclass   == (r2)->rrclass     && \
 161         (r1)->namehash  == (r2)->namehash    && \
 162         (r1)->rdlength  == (r2)->rdlength    && \
 163         (r1)->rdatahash == (r2)->rdatahash   && \
 164         SameRDataBody((r1), &(r2)->rdata->u, SameDomainName) && \
 165         SameDomainName((r1)->name, (r2)->name))
 166
 167 #define IdenticalSameNameRecord(r1,r2) ( \
 168         (r1)->rrtype    == (r2)->rrtype      && \
 169         (r1)->rrclass   == (r2)->rrclass     && \
 170         (r1)->rdlength  == (r2)->rdlength    && \
 171         (r1)->rdatahash == (r2)->rdatahash   && \
 172         SameRDataBody((r1), &(r2)->rdata->u, SameDomainName))
 173
 174 // A given RRType answers a QuestionType if RRType is CNAME, or types match, or QuestionType is ANY,
 175 // or the RRType is NSEC and positively asserts the nonexistence of the type being requested
 176 #define RRTypeAnswersQuestionType(R,Q) ((R)->rrtype == kDNSType_CNAME || (R)->rrtype == (Q) || (Q) == kDNSQType_ANY || RRAssertsNonexistence((R),(Q)))
 177 // Unicast NSEC records have the NSEC bit set whereas the multicast NSEC ones don't
 178 #define UNICAST_NSEC(rr) ((rr)->rrtype == kDNSType_NSEC && RRAssertsExistence((rr), kDNSType_NSEC))
 179
 180 extern mDNSu32 RDataHashValue(const ResourceRecord *const rr);
 181 extern mDNSBool SameRDataBody(const ResourceRecord *const r1, const RDataBody *const r2, DomainNameComparisonFn *samename);
 182 extern mDNSBool SameNameCacheRecordAnswersQuestion(const CacheRecord *const cr, const DNSQuestion *const q);
 183 extern mDNSBool ResourceRecordAnswersQuestion(const ResourceRecord *const rr, const DNSQuestion *const q);
 184 extern mDNSBool AuthRecordAnswersQuestion(const AuthRecord *const ar, const DNSQuestion *const q);
 185 extern mDNSBool CacheRecordAnswersQuestion(const CacheRecord *const cr, const DNSQuestion *const q);
 186 extern mDNSBool AnyTypeRecordAnswersQuestion (const AuthRecord *const ar, const DNSQuestion *const q);
 187 extern mDNSBool ResourceRecordAnswersUnicastResponse(const ResourceRecord *const rr, const DNSQuestion *const q);
 188 extern mDNSBool LocalOnlyRecordAnswersQuestion(AuthRecord *const rr, const DNSQuestion *const q);
 189 extern mDNSu16 GetRDLength(const ResourceRecord *const rr, mDNSBool estimate);
 190 extern mDNSBool ValidateRData(const mDNSu16 rrtype, const mDNSu16 rdlength, const RData *const rd);
 191 extern mStatus DNSNameToLowerCase(domainname *d, domainname *result);
 192
 193 #define GetRRDomainNameTarget(RR) (                                                                          \
 194         ((RR)->rrtype == kDNSType_NS || (RR)->rrtype == kDNSType_CNAME || (RR)->rrtype == kDNSType_PTR || (RR)->rrtype == kDNSType_DNAME) ? &(RR)->rdata->u.name        : \
 195         ((RR)->rrtype == kDNSType_MX || (RR)->rrtype == kDNSType_AFSDB || (RR)->rrtype == kDNSType_RT  || (RR)->rrtype == kDNSType_KX   ) ? &(RR)->rdata->u.mx.exchange : \
 196         ((RR)->rrtype == kDNSType_SRV                                  ) ? &(RR)->rdata->u.srv.target : mDNSNULL )
 197
 198 #define LocalRecordReady(X) ((X)->resrec.RecordType != kDNSRecordTypeUnique)
 199
 200 // ***************************************************************************
 201 #if COMPILER_LIKES_PRAGMA_MARK
 202 #pragma mark -
 203 #pragma mark - DNS Message Creation Functions
 204 #endif
 205
 206 extern void InitializeDNSMessage(DNSMessageHeader *h, mDNSOpaque16 id, mDNSOpaque16 flags);
 207 extern const mDNSu8 *FindCompressionPointer(const mDNSu8 *const base, const mDNSu8 *const end, const mDNSu8 *const domname);
 208 extern mDNSu8 *putDomainNameAsLabels(const DNSMessage *const msg, mDNSu8 *ptr, const mDNSu8 *const limit, const domainname *const name);
 209 extern mDNSu8 *putRData(const DNSMessage *const msg, mDNSu8 *ptr, const mDNSu8 *const limit, const ResourceRecord *const rr);
 210
 211 // If we have a single large record to put in the packet, then we allow the packet to be up to 9K bytes,
 212 // but in the normal case we try to keep the packets below 1500 to avoid IP fragmentation on standard Ethernet
 213
 214 #define AllowedRRSpace(msg) (((msg)->h.numAnswers || (msg)->h.numAuthorities || (msg)->h.numAdditionals) ? NormalMaxDNSMessageData : AbsoluteMaxDNSMessageData)
 215
 216 extern mDNSu8 *PutResourceRecordTTLWithLimit(DNSMessage *const msg, mDNSu8 *ptr, mDNSu16 *count, const ResourceRecord *rr,
 217     mDNSu32 ttl, const mDNSu8 *limit);
 218
 219 #define PutResourceRecordTTL(msg, ptr, count, rr, ttl) \
 220     PutResourceRecordTTLWithLimit((msg), (ptr), (count), (rr), (ttl), (msg)->data + AllowedRRSpace(msg))
 221
 222 #define PutResourceRecordTTLJumbo(msg, ptr, count, rr, ttl) \
 223     PutResourceRecordTTLWithLimit((msg), (ptr), (count), (rr), (ttl), (msg)->data + AbsoluteMaxDNSMessageData)
 224
 225 #define PutResourceRecord(MSG, P, C, RR) PutResourceRecordTTL((MSG), (P), (C), (RR), (RR)->rroriginalttl)
 226
 227 // The PutRR_OS variants assume a local variable 'm', put build the packet at m->omsg,
 228 // and assume local variables 'OwnerRecordSpace' & 'TraceRecordSpace' indicating how many bytes (if any) to reserve to add an OWNER/TRACER option at the end
 229 #define PutRR_OS_TTL(ptr, count, rr, ttl) \
 230     PutResourceRecordTTLWithLimit(&m->omsg, (ptr), (count), (rr), (ttl), m->omsg.data + AllowedRRSpace(&m->omsg) - OwnerRecordSpace - TraceRecordSpace)
 231
 232 #define PutRR_OS(P, C, RR) PutRR_OS_TTL((P), (C), (RR), (RR)->rroriginalttl)
 233
 234 extern mDNSu8 *putQuestion(DNSMessage *const msg, mDNSu8 *ptr, const mDNSu8 *const limit, const domainname *const name, mDNSu16 rrtype, mDNSu16 rrclass);
 235 extern mDNSu8 *putZone(DNSMessage *const msg, mDNSu8 *ptr, mDNSu8 *limit, const domainname *zone, mDNSOpaque16 zoneClass);
 236 extern mDNSu8 *putPrereqNameNotInUse(const domainname *const name, DNSMessage *const msg, mDNSu8 *const ptr, mDNSu8 *const end);
 237 extern mDNSu8 *putDeletionRecord(DNSMessage *msg, mDNSu8 *ptr, ResourceRecord *rr);
 238 extern mDNSu8 *putDeletionRecordWithLimit(DNSMessage *msg, mDNSu8 *ptr, ResourceRecord *rr, mDNSu8 *limit);
 239 extern mDNSu8 *putDeleteRRSetWithLimit(DNSMessage *msg, mDNSu8 *ptr, const domainname *name, mDNSu16 rrtype, mDNSu8 *limit);
 240 extern mDNSu8 *putDeleteAllRRSets(DNSMessage *msg, mDNSu8 *ptr, const domainname *name);
 241 extern mDNSu8 *putUpdateLease(DNSMessage *msg, mDNSu8 *ptr, mDNSu32 lease);
 242 extern mDNSu8 *putUpdateLeaseWithLimit(DNSMessage *msg, mDNSu8 *ptr, mDNSu32 lease, mDNSu8 *limit);
 243
 244 extern int baseEncode(char *buffer, int blen, const mDNSu8 *data, int len, int encAlg);
 245 extern void NSEC3Parse(const ResourceRecord *const rr, mDNSu8 **salt, int *hashLength, mDNSu8 **nxtName, int *bitmaplen, mDNSu8 **bitmap);
 246
 247 // ***************************************************************************
 248 #if COMPILER_LIKES_PRAGMA_MARK
 249 #pragma mark -
 250 #pragma mark - DNS Message Parsing Functions
 251 #endif
 252
 253 #define HashSlotFromNameHash(X) ((X) % CACHE_HASH_SLOTS)
 254 extern mDNSu32 DomainNameHashValue(const domainname *const name);
 255 extern void SetNewRData(ResourceRecord *const rr, RData *NewRData, mDNSu16 rdlength);
 256 extern const mDNSu8 *skipDomainName(const DNSMessage *const msg, const mDNSu8 *ptr, const mDNSu8 *const end);
 257 extern const mDNSu8 *getDomainName(const DNSMessage *const msg, const mDNSu8 *ptr, const mDNSu8 *const end,
 258                                    domainname *const name);
 259 extern const mDNSu8 *skipResourceRecord(const DNSMessage *msg, const mDNSu8 *ptr, const mDNSu8 *end);
 260 extern const mDNSu8 *GetLargeResourceRecord(mDNS *const m, const DNSMessage * const msg, const mDNSu8 *ptr,
 261                                             const mDNSu8 * end, const mDNSInterfaceID InterfaceID, mDNSu8 RecordType, LargeCacheRecord *const largecr);
 262 extern mDNSBool SetRData(const DNSMessage *const msg, const mDNSu8 *ptr, const mDNSu8 *end, ResourceRecord *rr,
 263     mDNSu16 rdlength);
 264 extern const mDNSu8 *skipQuestion(const DNSMessage *msg, const mDNSu8 *ptr, const mDNSu8 *end);
 265 extern const mDNSu8 *getQuestion(const DNSMessage *msg, const mDNSu8 *ptr, const mDNSu8 *end, const mDNSInterfaceID InterfaceID,
 266                                  DNSQuestion *question);
 267 extern const mDNSu8 *LocateAnswers(const DNSMessage *const msg, const mDNSu8 *const end);
 268 extern const mDNSu8 *LocateAuthorities(const DNSMessage *const msg, const mDNSu8 *const end);
 269 extern const mDNSu8 *LocateAdditionals(const DNSMessage *const msg, const mDNSu8 *const end);
 270 extern const mDNSu8 *LocateOptRR(const DNSMessage *const msg, const mDNSu8 *const end, int minsize);
 271 extern const rdataOPT *GetLLQOptData(mDNS *const m, const DNSMessage *const msg, const mDNSu8 *const end);
 272 extern mDNSBool GetPktLease(mDNS *const m, const DNSMessage *const msg, const mDNSu8 *const end, mDNSu32 *const lease);
 273 extern void DumpPacket(mStatus status, mDNSBool sent, const char *transport, const mDNSAddr *srcaddr, mDNSIPPort srcport,
 274     const mDNSAddr *dstaddr, mDNSIPPort dstport, const DNSMessage *const msg, const mDNSu8 *const end,
 275     mDNSInterfaceID interfaceID);
 276 extern mDNSBool RRAssertsNonexistence(const ResourceRecord *const rr, mDNSu16 type);
 277 extern mDNSBool RRAssertsExistence(const ResourceRecord *const rr, mDNSu16 type);
 278 extern mDNSBool BitmapTypeCheck(mDNSu8 *bmap, int bitmaplen, mDNSu16 type);
 279
 280 extern mDNSu16 swap16(mDNSu16 x);
 281 extern mDNSu32 swap32(mDNSu32 x);
 282
 283 extern mDNSBool GetReverseIPv6Addr(const domainname *inQName, mDNSu8 outIPv6[16]);
 284
 285 // ***************************************************************************
 286 #if COMPILER_LIKES_PRAGMA_MARK
 287 #pragma mark -
 288 #pragma mark - Packet Sending Functions
 289 #endif
 290 extern mStatus mDNSSendDNSMessage(mDNS *const m, DNSMessage *const msg, mDNSu8 *end,
 291                                   mDNSInterfaceID InterfaceID, TCPSocket *tcpSrc, UDPSocket *udpSrc, const mDNSAddr *dst,
 292                                   mDNSIPPort dstport, DomainAuthInfo *authInfo, mDNSBool useBackgroundTrafficClass);
 293
 294 // ***************************************************************************
 295 #if COMPILER_LIKES_PRAGMA_MARK
 296 #pragma mark -
 297 #pragma mark - RR List Management & Task Management
 298 #endif
 299
 300 extern void ShowTaskSchedulingError(mDNS *const m);
 301 extern void mDNS_Lock_(mDNS *const m, const char * const functionname);
 302 extern void mDNS_Unlock_(mDNS *const m, const char * const functionname);
 303
 304 #if defined(_WIN32)
 305  #define __func__ __FUNCTION__
 306 #endif
 307
 308 #define mDNS_Lock(X) mDNS_Lock_((X), __func__)
 309
 310 #define mDNS_Unlock(X) mDNS_Unlock_((X), __func__)
 311
 312 #define mDNS_CheckLock(X) \
 313     if ((X)->mDNS_busy != (X)->mDNS_reentrancy+1) LogMsg("%s: Lock not held! mDNS_busy (%ld) mDNS_reentrancy (%ld)", __func__, (X)->mDNS_busy, (X)->mDNS_reentrancy)
 314
 315 #define mDNS_DropLockBeforeCallback() do { m->mDNS_reentrancy++; \
 316     if (m->mDNS_busy != m->mDNS_reentrancy) LogMsg("%s: Locking Failure! mDNS_busy (%ld) != mDNS_reentrancy (%ld)", __func__, m->mDNS_busy, m->mDNS_reentrancy); \
 317     } while (0)
 318
 319 #define mDNS_ReclaimLockAfterCallback() do { \
 320     if (m->mDNS_busy != m->mDNS_reentrancy) LogMsg("%s: Unlocking Failure! mDNS_busy (%ld) != mDNS_reentrancy (%ld)", __func__, m->mDNS_busy, m->mDNS_reentrancy); \
 321     m->mDNS_reentrancy--; } while (0)
 322
 323 #ifdef  __cplusplus
 324 }
 325 #endif
 326
 327 #endif // __DNSCOMMON_H_