mDNSCore/DNSCommon.h - platform/external/mdnsresponder - Git at Google

 /* -*- Mode: C; tab-width: 4 -*-
  *
  * Copyright (c) 2002-2003 Apple Computer, 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     = 0x78,		// Operation type
 	kDNSFlag0_OP_StdQuery = 0x00,
 	kDNSFlag0_OP_Iquery   = 0x08,
 	kDNSFlag0_OP_Status   = 0x10,
 	kDNSFlag0_OP_Unused3  = 0x18,
 	kDNSFlag0_OP_Notify   = 0x20,
 	kDNSFlag0_OP_Update   = 0x28,

 	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
 	} 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 COMPILER_LIKES_PRAGMA_MARK
 #pragma mark -
 #pragma mark - Domain Name Utility Functions
 #endif

 #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))

 #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)))
 #define RRAssertsNonexistence(R,T) ((R)->rrtype == kDNSType_NSEC && (T) < kDNSQType_ANY && !((R)->rdata->u.nsec.bitmap[(T)>>3] & (128 >> ((T)&7))))

 extern mDNSu32 RDataHashValue(const ResourceRecord *const rr);
 extern mDNSBool SameRDataBody(const ResourceRecord *const r1, const RDataBody *const r2, DomainNameComparisonFn *samename);
 extern mDNSBool SameNameRecordAnswersQuestion(const ResourceRecord *const rr, const DNSQuestion *const q);
 extern mDNSBool ResourceRecordAnswersQuestion(const ResourceRecord *const rr, const DNSQuestion *const q);
 extern mDNSBool AnyTypeRecordAnswersQuestion (const ResourceRecord *const rr, 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);

 #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, 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 a local variable 'OwnerRecordSpace' indicating how many bytes (if any) to reserve to add an OWNER 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)

 #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 *end, mDNSu32 lease);
 extern mDNSu8 *putUpdateLeaseWithLimit(DNSMessage *msg, mDNSu8 *ptr, mDNSu32 lease, mDNSu8 *limit);

 extern mDNSu8 *putHINFO(const mDNS *const m, DNSMessage *const msg, mDNSu8 *ptr, DomainAuthInfo *authInfo, mDNSu8 *limit);

 // ***************************************************************************
 #if COMPILER_LIKES_PRAGMA_MARK
 #pragma mark -
 #pragma mark - DNS Message Parsing Functions
 #endif

 #define AuthHashSlot(X) (DomainNameHashValue(X) % AUTH_HASH_SLOTS)
 #define HashSlot(X) (DomainNameHashValue(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 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 mDNSu32 GetPktLease(mDNS *m, DNSMessage *msg, const mDNSu8 *end);
 extern void DumpPacket(mDNS *const m, mStatus status, mDNSBool sent, char *transport,
 	const mDNSAddr *srcaddr, mDNSIPPort srcport,
 	const mDNSAddr *dstaddr, mDNSIPPort dstport, const DNSMessage *const msg, const mDNSu8 *const end);

 // ***************************************************************************
 #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, UDPSocket *src, const mDNSAddr *dst, mDNSIPPort dstport, TCPSocket *sock, DomainAuthInfo *authInfo);

 // ***************************************************************************
 #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_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_
	/* -- Mode: C; tab-width: 4 --
	*
	* Copyright (c) 2002-2003 Apple Computer, 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 = 0x78, // Operation type
	kDNSFlag0_OP_StdQuery = 0x00,
	kDNSFlag0_OP_Iquery = 0x08,
	kDNSFlag0_OP_Status = 0x10,
	kDNSFlag0_OP_Unused3 = 0x18,
	kDNSFlag0_OP_Notify = 0x20,
	kDNSFlag0_OP_Update = 0x28,

	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
	} 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 COMPILER_LIKES_PRAGMA_MARK
	#pragma mark -
	#pragma mark - Domain Name Utility Functions
	#endif

	#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))

	#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)))
	#define RRAssertsNonexistence(R,T) ((R)->rrtype == kDNSType_NSEC && (T) < kDNSQType_ANY && !((R)->rdata->u.nsec.bitmap[(T)>>3] & (128 >> ((T)&7))))

	extern mDNSu32 RDataHashValue(const ResourceRecord *const rr);
	extern mDNSBool SameRDataBody(const ResourceRecord const r1, const RDataBody const r2, DomainNameComparisonFn *samename);
	extern mDNSBool SameNameRecordAnswersQuestion(const ResourceRecord const rr, const DNSQuestion const q);
	extern mDNSBool ResourceRecordAnswersQuestion(const ResourceRecord const rr, const DNSQuestion const q);
	extern mDNSBool AnyTypeRecordAnswersQuestion (const ResourceRecord const rr, 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);

	#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, 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 a local variable 'OwnerRecordSpace' indicating how many bytes (if any) to reserve to add an OWNER 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)

	#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 *end, mDNSu32 lease);
	extern mDNSu8 putUpdateLeaseWithLimit(DNSMessage msg, mDNSu8 ptr, mDNSu32 lease, mDNSu8 limit);

	extern mDNSu8 putHINFO(const mDNS const m, DNSMessage const msg, mDNSu8 ptr, DomainAuthInfo authInfo, mDNSu8 limit);

	// ***************************************************************************
	#if COMPILER_LIKES_PRAGMA_MARK
	#pragma mark -
	#pragma mark - DNS Message Parsing Functions
	#endif

	#define AuthHashSlot(X) (DomainNameHashValue(X) % AUTH_HASH_SLOTS)
	#define HashSlot(X) (DomainNameHashValue(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 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 mDNSu32 GetPktLease(mDNS m, DNSMessage msg, const mDNSu8 *end);
	extern void DumpPacket(mDNS const m, mStatus status, mDNSBool sent, char transport,
	const mDNSAddr *srcaddr, mDNSIPPort srcport,
	const mDNSAddr dstaddr, mDNSIPPort dstport, const DNSMessage const msg, const mDNSu8 *const end);

	// ***************************************************************************
	#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, UDPSocket src, const mDNSAddr dst, mDNSIPPort dstport, TCPSocket sock, DomainAuthInfo authInfo);

	// ***************************************************************************
	#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_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_