/* -*- Mode: C; tab-width: 4 -*- * * Copyright (c) 2002-2020 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 * * http://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 __DNSCOMMON_H_ #define __DNSCOMMON_H_ #include "mDNSEmbeddedAPI.h" #ifdef __cplusplus extern "C" { #endif //************************************************************************************************************* // Macros // Note: The C preprocessor stringify operator ('#') makes a string from its argument, without macro expansion // e.g. If "version" is #define'd to be "4", then STRINGIFY_AWE(version) will return the string "version", not "4" // To expand "version" to its value before making the string, use STRINGIFY(version) instead #define STRINGIFY_ARGUMENT_WITHOUT_EXPANSION(s) # s #define STRINGIFY(s) STRINGIFY_ARGUMENT_WITHOUT_EXPANSION(s) // *************************************************************************** #if COMPILER_LIKES_PRAGMA_MARK #pragma mark - DNS Protocol Constants #endif typedef enum { kDNSFlag0_QR_Mask = 0x80, // Query or response? kDNSFlag0_QR_Query = 0x00, kDNSFlag0_QR_Response = 0x80, kDNSFlag0_OP_Mask = 0xF << 3, // Operation type kDNSFlag0_OP_StdQuery = 0x0 << 3, kDNSFlag0_OP_Iquery = 0x1 << 3, kDNSFlag0_OP_Status = 0x2 << 3, kDNSFlag0_OP_Unused3 = 0x3 << 3, kDNSFlag0_OP_Notify = 0x4 << 3, kDNSFlag0_OP_Update = 0x5 << 3, kDNSFlag0_OP_DSO = 0x6 << 3, kDNSFlag0_QROP_Mask = kDNSFlag0_QR_Mask | kDNSFlag0_OP_Mask, kDNSFlag0_AA = 0x04, // Authoritative Answer? kDNSFlag0_TC = 0x02, // Truncated? kDNSFlag0_RD = 0x01, // Recursion Desired? kDNSFlag1_RA = 0x80, // Recursion Available? kDNSFlag1_Zero = 0x40, // Reserved; must be zero kDNSFlag1_AD = 0x20, // Authentic Data [RFC 2535] kDNSFlag1_CD = 0x10, // Checking Disabled [RFC 2535] kDNSFlag1_RC_Mask = 0x0F, // Response code kDNSFlag1_RC_NoErr = 0x00, kDNSFlag1_RC_FormErr = 0x01, kDNSFlag1_RC_ServFail = 0x02, kDNSFlag1_RC_NXDomain = 0x03, kDNSFlag1_RC_NotImpl = 0x04, kDNSFlag1_RC_Refused = 0x05, kDNSFlag1_RC_YXDomain = 0x06, kDNSFlag1_RC_YXRRSet = 0x07, kDNSFlag1_RC_NXRRSet = 0x08, kDNSFlag1_RC_NotAuth = 0x09, kDNSFlag1_RC_NotZone = 0x0A, kDNSFlag1_RC_DSOTypeNI = 0x0B } DNS_Flags; typedef enum { TSIG_ErrBadSig = 16, TSIG_ErrBadKey = 17, TSIG_ErrBadTime = 18 } TSIG_ErrorCode; // *************************************************************************** #if COMPILER_LIKES_PRAGMA_MARK #pragma mark - #pragma mark - General Utility Functions #endif extern NetworkInterfaceInfo *GetFirstActiveInterface(NetworkInterfaceInfo *intf); extern mDNSInterfaceID GetNextActiveInterfaceID(const NetworkInterfaceInfo *intf); extern mDNSu32 mDNSRandom(mDNSu32 max); // Returns pseudo-random result from zero to max inclusive #if !MDNSRESPONDER_SUPPORTS(APPLE, QUERIER) extern mDNSu32 mDNS_GetNextResolverGroupID(void); #endif // *************************************************************************** #if COMPILER_LIKES_PRAGMA_MARK #pragma mark - #pragma mark - Domain Name Utility Functions #endif #define mDNSSubTypeLabel "\x04_sub" #define mDNSIsDigit(X) ((X) >= '0' && (X) <= '9') #define mDNSIsUpperCase(X) ((X) >= 'A' && (X) <= 'Z') #define mDNSIsLowerCase(X) ((X) >= 'a' && (X) <= 'z') #define mDNSIsLetter(X) (mDNSIsUpperCase(X) || mDNSIsLowerCase(X)) // We believe we have adequate safeguards to protect against cache poisoning. // In the event that someone does find a workable cache poisoning attack, we want to limit the lifetime of the poisoned entry. // We set the maximum allowable TTL to one hour. // With the 25% correction factor to avoid the DNS Zeno's paradox bug, that gives us an actual maximum lifetime of 75 minutes. #define mDNSMaximumMulticastTTLSeconds (mDNSu32)4500 #define mDNSMaximumUnicastTTLSeconds (mDNSu32)3600 #define mDNSValidHostChar(X, notfirst, notlast) (mDNSIsLetter(X) || mDNSIsDigit(X) || ((notfirst) && (notlast) && (X) == '-') ) extern mDNSu16 CompressedDomainNameLength(const domainname *const name, const domainname *parent); extern int CountLabels(const domainname *d); extern const domainname *SkipLeadingLabels(const domainname *d, int skip); extern mDNSu32 TruncateUTF8ToLength(mDNSu8 *string, mDNSu32 length, mDNSu32 max); extern mDNSBool LabelContainsSuffix(const domainlabel *const name, const mDNSBool RichText); extern mDNSu32 RemoveLabelSuffix(domainlabel *name, mDNSBool RichText); extern void AppendLabelSuffix(domainlabel *const name, mDNSu32 val, const mDNSBool RichText); #define ValidateDomainName(N) (DomainNameLength(N) <= MAX_DOMAIN_NAME) // *************************************************************************** #if COMPILER_LIKES_PRAGMA_MARK #pragma mark - #pragma mark - Resource Record Utility Functions #endif // IdenticalResourceRecord returns true if two resources records have // the same name, type, class, and identical rdata (InterfaceID and TTL may differ) // IdenticalSameNameRecord is the same, except it skips the expensive SameDomainName() check, // which is at its most expensive and least useful in cases where we know in advance that the names match // Note: The dominant use of IdenticalResourceRecord is from ProcessQuery(), handling known-answer lists. In this case // it's common to have a whole bunch or records with exactly the same name (e.g. "_http._tcp.local") but different RDATA. // The SameDomainName() check is expensive when the names match, and in this case *all* the names match, so we // used to waste a lot of CPU time verifying that the names match, only then to find that the RDATA is different. // We observed mDNSResponder spending 30% of its total CPU time on this single task alone. // By swapping the checks so that we check the RDATA first, we can quickly detect when it's different // (99% of the time) and then bail out before we waste time on the expensive SameDomainName() check. #define IdenticalResourceRecord(r1,r2) ( \ (r1)->rrtype == (r2)->rrtype && \ (r1)->rrclass == (r2)->rrclass && \ (r1)->namehash == (r2)->namehash && \ (r1)->rdlength == (r2)->rdlength && \ (r1)->rdatahash == (r2)->rdatahash && \ SameRDataBody((r1), &(r2)->rdata->u, SameDomainName) && \ SameDomainName((r1)->name, (r2)->name)) #define IdenticalSameNameRecord(r1,r2) ( \ (r1)->rrtype == (r2)->rrtype && \ (r1)->rrclass == (r2)->rrclass && \ (r1)->rdlength == (r2)->rdlength && \ (r1)->rdatahash == (r2)->rdatahash && \ SameRDataBody((r1), &(r2)->rdata->u, SameDomainName)) // A given RRType answers a QuestionType if RRType is CNAME, or types match, or QuestionType is ANY, // or the RRType is NSEC and positively asserts the nonexistence of the type being requested #define RRTypeAnswersQuestionType(R,Q) ((R)->rrtype == kDNSType_CNAME || (R)->rrtype == (Q) || (Q) == kDNSQType_ANY || RRAssertsNonexistence((R),(Q))) // Unicast NSEC records have the NSEC bit set whereas the multicast NSEC ones don't #define UNICAST_NSEC(rr) ((rr)->rrtype == kDNSType_NSEC && RRAssertsExistence((rr), kDNSType_NSEC)) extern mDNSu32 RDataHashValue(const ResourceRecord *const rr); extern mDNSBool SameRDataBody(const ResourceRecord *const r1, const RDataBody *const r2, DomainNameComparisonFn *samename); extern mDNSBool SameNameCacheRecordAnswersQuestion(const CacheRecord *const cr, const DNSQuestion *const q); extern mDNSBool ResourceRecordAnswersQuestion(const ResourceRecord *const rr, const DNSQuestion *const q); extern mDNSBool AuthRecordAnswersQuestion(const AuthRecord *const ar, const DNSQuestion *const q); extern mDNSBool CacheRecordAnswersQuestion(const CacheRecord *const cr, const DNSQuestion *const q); extern mDNSBool AnyTypeRecordAnswersQuestion (const AuthRecord *const ar, const DNSQuestion *const q); extern mDNSBool ResourceRecordAnswersUnicastResponse(const ResourceRecord *const rr, const DNSQuestion *const q); extern mDNSBool LocalOnlyRecordAnswersQuestion(AuthRecord *const rr, const DNSQuestion *const q); extern mDNSu16 GetRDLength(const ResourceRecord *const rr, mDNSBool estimate); extern mDNSBool ValidateRData(const mDNSu16 rrtype, const mDNSu16 rdlength, const RData *const rd); extern mStatus DNSNameToLowerCase(domainname *d, domainname *result); #define GetRRDomainNameTarget(RR) ( \ ((RR)->rrtype == kDNSType_NS || (RR)->rrtype == kDNSType_CNAME || (RR)->rrtype == kDNSType_PTR || (RR)->rrtype == kDNSType_DNAME) ? &(RR)->rdata->u.name : \ ((RR)->rrtype == kDNSType_MX || (RR)->rrtype == kDNSType_AFSDB || (RR)->rrtype == kDNSType_RT || (RR)->rrtype == kDNSType_KX ) ? &(RR)->rdata->u.mx.exchange : \ ((RR)->rrtype == kDNSType_SRV ) ? &(RR)->rdata->u.srv.target : mDNSNULL ) #define LocalRecordReady(X) ((X)->resrec.RecordType != kDNSRecordTypeUnique) // *************************************************************************** #if COMPILER_LIKES_PRAGMA_MARK #pragma mark - #pragma mark - DNS Message Creation Functions #endif extern void InitializeDNSMessage(DNSMessageHeader *h, mDNSOpaque16 id, mDNSOpaque16 flags); extern const mDNSu8 *FindCompressionPointer(const mDNSu8 *const base, const mDNSu8 *const end, const mDNSu8 *const domname); extern mDNSu8 *putDomainNameAsLabels(const DNSMessage *const msg, mDNSu8 *ptr, const mDNSu8 *const limit, const domainname *const name); extern mDNSu8 *putRData(const DNSMessage *const msg, mDNSu8 *ptr, const mDNSu8 *const limit, const ResourceRecord *const rr); // If we have a single large record to put in the packet, then we allow the packet to be up to 9K bytes, // but in the normal case we try to keep the packets below 1500 to avoid IP fragmentation on standard Ethernet #define AllowedRRSpace(msg) (((msg)->h.numAnswers || (msg)->h.numAuthorities || (msg)->h.numAdditionals) ? NormalMaxDNSMessageData : AbsoluteMaxDNSMessageData) extern mDNSu8 *PutResourceRecordTTLWithLimit(DNSMessage *const msg, mDNSu8 *ptr, mDNSu16 *count, const ResourceRecord *rr, mDNSu32 ttl, const mDNSu8 *limit); #define PutResourceRecordTTL(msg, ptr, count, rr, ttl) \ PutResourceRecordTTLWithLimit((msg), (ptr), (count), (rr), (ttl), (msg)->data + AllowedRRSpace(msg)) #define PutResourceRecordTTLJumbo(msg, ptr, count, rr, ttl) \ PutResourceRecordTTLWithLimit((msg), (ptr), (count), (rr), (ttl), (msg)->data + AbsoluteMaxDNSMessageData) #define PutResourceRecord(MSG, P, C, RR) PutResourceRecordTTL((MSG), (P), (C), (RR), (RR)->rroriginalttl) // The PutRR_OS variants assume a local variable 'm', put build the packet at m->omsg, // and assume local variables 'OwnerRecordSpace' & 'TraceRecordSpace' indicating how many bytes (if any) to reserve to add an OWNER/TRACER option at the end #define PutRR_OS_TTL(ptr, count, rr, ttl) \ PutResourceRecordTTLWithLimit(&m->omsg, (ptr), (count), (rr), (ttl), m->omsg.data + AllowedRRSpace(&m->omsg) - OwnerRecordSpace - TraceRecordSpace) #define PutRR_OS(P, C, RR) PutRR_OS_TTL((P), (C), (RR), (RR)->rroriginalttl) extern mDNSu8 *putQuestion(DNSMessage *const msg, mDNSu8 *ptr, const mDNSu8 *const limit, const domainname *const name, mDNSu16 rrtype, mDNSu16 rrclass); extern mDNSu8 *putZone(DNSMessage *const msg, mDNSu8 *ptr, mDNSu8 *limit, const domainname *zone, mDNSOpaque16 zoneClass); extern mDNSu8 *putPrereqNameNotInUse(const domainname *const name, DNSMessage *const msg, mDNSu8 *const ptr, mDNSu8 *const end); extern mDNSu8 *putDeletionRecord(DNSMessage *msg, mDNSu8 *ptr, ResourceRecord *rr); extern mDNSu8 *putDeletionRecordWithLimit(DNSMessage *msg, mDNSu8 *ptr, ResourceRecord *rr, mDNSu8 *limit); extern mDNSu8 *putDeleteRRSetWithLimit(DNSMessage *msg, mDNSu8 *ptr, const domainname *name, mDNSu16 rrtype, mDNSu8 *limit); extern mDNSu8 *putDeleteAllRRSets(DNSMessage *msg, mDNSu8 *ptr, const domainname *name); extern mDNSu8 *putUpdateLease(DNSMessage *msg, mDNSu8 *ptr, mDNSu32 lease); extern mDNSu8 *putUpdateLeaseWithLimit(DNSMessage *msg, mDNSu8 *ptr, mDNSu32 lease, mDNSu8 *limit); extern int baseEncode(char *buffer, int blen, const mDNSu8 *data, int len, int encAlg); extern void NSEC3Parse(const ResourceRecord *const rr, mDNSu8 **salt, int *hashLength, mDNSu8 **nxtName, int *bitmaplen, mDNSu8 **bitmap); // *************************************************************************** #if COMPILER_LIKES_PRAGMA_MARK #pragma mark - #pragma mark - DNS Message Parsing Functions #endif #define HashSlotFromNameHash(X) ((X) % CACHE_HASH_SLOTS) extern mDNSu32 DomainNameHashValue(const domainname *const name); extern void SetNewRData(ResourceRecord *const rr, RData *NewRData, mDNSu16 rdlength); extern const mDNSu8 *skipDomainName(const DNSMessage *const msg, const mDNSu8 *ptr, const mDNSu8 *const end); extern const mDNSu8 *getDomainName(const DNSMessage *const msg, const mDNSu8 *ptr, const mDNSu8 *const end, domainname *const name); extern const mDNSu8 *skipResourceRecord(const DNSMessage *msg, const mDNSu8 *ptr, const mDNSu8 *end); extern const mDNSu8 *GetLargeResourceRecord(mDNS *const m, const DNSMessage * const msg, const mDNSu8 *ptr, const mDNSu8 * end, const mDNSInterfaceID InterfaceID, mDNSu8 RecordType, LargeCacheRecord *const largecr); extern mDNSBool SetRData(const DNSMessage *const msg, const mDNSu8 *ptr, const mDNSu8 *end, ResourceRecord *rr, mDNSu16 rdlength); extern const mDNSu8 *skipQuestion(const DNSMessage *msg, const mDNSu8 *ptr, const mDNSu8 *end); extern const mDNSu8 *getQuestion(const DNSMessage *msg, const mDNSu8 *ptr, const mDNSu8 *end, const mDNSInterfaceID InterfaceID, DNSQuestion *question); extern const mDNSu8 *LocateAnswers(const DNSMessage *const msg, const mDNSu8 *const end); extern const mDNSu8 *LocateAuthorities(const DNSMessage *const msg, const mDNSu8 *const end); extern const mDNSu8 *LocateAdditionals(const DNSMessage *const msg, const mDNSu8 *const end); extern const mDNSu8 *LocateOptRR(const DNSMessage *const msg, const mDNSu8 *const end, int minsize); extern const rdataOPT *GetLLQOptData(mDNS *const m, const DNSMessage *const msg, const mDNSu8 *const end); extern mDNSBool GetPktLease(mDNS *const m, const DNSMessage *const msg, const mDNSu8 *const end, mDNSu32 *const lease); extern 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); extern mDNSBool RRAssertsNonexistence(const ResourceRecord *const rr, mDNSu16 type); extern mDNSBool RRAssertsExistence(const ResourceRecord *const rr, mDNSu16 type); extern mDNSBool BitmapTypeCheck(mDNSu8 *bmap, int bitmaplen, mDNSu16 type); extern mDNSu16 swap16(mDNSu16 x); extern mDNSu32 swap32(mDNSu32 x); extern mDNSBool GetReverseIPv6Addr(const domainname *inQName, mDNSu8 outIPv6[16]); // *************************************************************************** #if COMPILER_LIKES_PRAGMA_MARK #pragma mark - #pragma mark - Packet Sending Functions #endif extern 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); // *************************************************************************** #if COMPILER_LIKES_PRAGMA_MARK #pragma mark - #pragma mark - RR List Management & Task Management #endif extern void ShowTaskSchedulingError(mDNS *const m); extern void mDNS_Lock_(mDNS *const m, const char * const functionname); extern void mDNS_Unlock_(mDNS *const m, const char * const functionname); #if defined(_WIN32) #define __func__ __FUNCTION__ #endif #define mDNS_Lock(X) mDNS_Lock_((X), __func__) #define mDNS_Unlock(X) mDNS_Unlock_((X), __func__) #define mDNS_CheckLock(X) \ 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) #define mDNS_DropLockBeforeCallback() do { m->mDNS_reentrancy++; \ if (m->mDNS_busy != m->mDNS_reentrancy) LogMsg("%s: Locking Failure! mDNS_busy (%ld) != mDNS_reentrancy (%ld)", __func__, m->mDNS_busy, m->mDNS_reentrancy); \ } while (0) #define mDNS_ReclaimLockAfterCallback() do { \ if (m->mDNS_busy != m->mDNS_reentrancy) LogMsg("%s: Unlocking Failure! mDNS_busy (%ld) != mDNS_reentrancy (%ld)", __func__, m->mDNS_busy, m->mDNS_reentrancy); \ m->mDNS_reentrancy--; } while (0) #ifdef __cplusplus } #endif #endif // __DNSCOMMON_H_