text:
#ifndef __mDNSClientAPI_h
#define __mDNSClientAPI_h

#if defined(EFI32) || defined(EFI64) || defined(EFIX64)
// EFI doesn't have stdarg.h unless it's building with GCC.
#include "Tiano.h"
#if !defined(__GNUC__)
#define va_list         VA_LIST
#define va_start(a, b)  VA_START(a, b)
#define va_end(a)       VA_END(a)
#define va_arg(a, b)    VA_ARG(a, b)
#endif
#else
#include <stdarg.h>		// stdarg.h is required for for va_list support for the mDNS_vsnprintf declaration
#endif

#include "mDNSDebug.h"
#if APPLE_OSX_mDNSResponder
#include <uuid/uuid.h>
#endif

#ifdef __cplusplus
	extern "C" {
#endif

// ***************************************************************************
// Function scope indicators

// If you see "mDNSlocal" before a function name in a C file, it means the function is not callable outside this file
#ifndef mDNSlocal
#define mDNSlocal static
#endif
// If you see "mDNSexport" before a symbol in a C file, it means the symbol is exported for use by clients
// For every "mDNSexport" in a C file, there needs to be a corresponding "extern" declaration in some header file
// (When a C file #includes a header file, the "extern" declarations tell the compiler:
// "This symbol exists -- but not necessarily in this C file.")
#ifndef mDNSexport
#define mDNSexport
#endif

// Explanation: These local/export markers are a little habit of mine for signaling the programmers' intentions.
// When "mDNSlocal" is just a synonym for "static", and "mDNSexport" is a complete no-op, you could be
// forgiven for asking what purpose they serve. The idea is that if you see "mDNSexport" in front of a
// function definition it means the programmer intended it to be exported and callable from other files
// in the project. If you see "mDNSlocal" in front of a function definition it means the programmer
// intended it to be private to that file. If you see neither in front of a function definition it
// means the programmer forgot (so you should work out which it is supposed to be, and fix it).
// Using "mDNSlocal" instead of "static" makes it easier to do a textual searches for one or the other.
// For example you can do a search for "static" to find if any functions declare any local variables as "static"
// (generally a bad idea unless it's also "const", because static storage usually risks being non-thread-safe)
// without the results being cluttered with hundreds of matches for functions declared static.
// - Stuart Cheshire

// ***************************************************************************
// Structure packing macro

// If we're not using GNUC, it's not fatal.
// Most compilers naturally pack the on-the-wire structures correctly anyway, so a plain "struct" is usually fine.
// In the event that structures are not packed correctly, mDNS_Init() will detect this and report an error, so the
// developer will know what's wrong, and can investigate what needs to be done on that compiler to provide proper packing.
#ifndef packedstruct
 #if ((__GNUC__ > 2) || ((__GNUC__ == 2) && (__GNUC_MINOR__ >= 9)))
  #define packedstruct struct __attribute__((__packed__))
  #define packedunion  union  __attribute__((__packed__))
 #else
  #define packedstruct struct
  #define packedunion  union
 #endif
#endif

// ***************************************************************************
#if 0
#pragma mark - DNS Resource Record class and type constants
#endif

typedef enum							// From RFC 1035
	{
	kDNSClass_IN               = 1,		// Internet
	kDNSClass_CS               = 2,		// CSNET
	kDNSClass_CH               = 3,		// CHAOS
	kDNSClass_HS               = 4,		// Hesiod
	kDNSClass_NONE             = 254,	// Used in DNS UPDATE [RFC 2136]

	kDNSClass_Mask             = 0x7FFF,// Multicast DNS uses the bottom 15 bits to identify the record class...
	kDNSClass_UniqueRRSet      = 0x8000,// ... and the top bit indicates that all other cached records are now invalid

	kDNSQClass_ANY             = 255,	// Not a DNS class, but a DNS query class, meaning "all classes"
	kDNSQClass_UnicastResponse = 0x8000	// Top bit set in a question means "unicast response acceptable"
	} DNS_ClassValues;

typedef enum				// From RFC 1035
	{
	kDNSType_A = 1,			//  1 Address
	kDNSType_NS,			//  2 Name Server
	kDNSType_MD,			//  3 Mail Destination
	kDNSType_MF,			//  4 Mail Forwarder
	kDNSType_CNAME,			//  5 Canonical Name
	kDNSType_SOA,			//  6 Start of Authority
	kDNSType_MB,			//  7 Mailbox
	kDNSType_MG,			//  8 Mail Group
	kDNSType_MR,			//  9 Mail Rename
	kDNSType_NULL,			// 10 NULL RR
	kDNSType_WKS,			// 11 Well-known-service
	kDNSType_PTR,			// 12 Domain name pointer
	kDNSType_HINFO,			// 13 Host information
	kDNSType_MINFO,			// 14 Mailbox information
	kDNSType_MX,			// 15 Mail Exchanger
	kDNSType_TXT,			// 16 Arbitrary text string
	kDNSType_RP,			// 17 Responsible person
	kDNSType_AFSDB,			// 18 AFS cell database
	kDNSType_X25,			// 19 X_25 calling address
	kDNSType_ISDN,			// 20 ISDN calling address
	kDNSType_RT,			// 21 Router
	kDNSType_NSAP,			// 22 NSAP address
	kDNSType_NSAP_PTR,		// 23 Reverse NSAP lookup (deprecated)
	kDNSType_SIG,			// 24 Security signature
	kDNSType_KEY,			// 25 Security key
	kDNSType_PX,			// 26 X.400 mail mapping
	kDNSType_GPOS,			// 27 Geographical position (withdrawn)
	kDNSType_AAAA,			// 28 IPv6 Address
	kDNSType_LOC,			// 29 Location Information
	kDNSType_NXT,			// 30 Next domain (security)
	kDNSType_EID,			// 31 Endpoint identifier
	kDNSType_NIMLOC,		// 32 Nimrod Locator
	kDNSType_SRV,			// 33 Service record
	kDNSType_ATMA,			// 34 ATM Address
	kDNSType_NAPTR,			// 35 Naming Authority PoinTeR
	kDNSType_KX,			// 36 Key Exchange
	kDNSType_CERT,			// 37 Certification record
	kDNSType_A6,			// 38 IPv6 Address (deprecated)
	kDNSType_DNAME,			// 39 Non-terminal DNAME (for IPv6)
	kDNSType_SINK,			// 40 Kitchen sink (experimental)
	kDNSType_OPT,			// 41 EDNS0 option (meta-RR)
	kDNSType_APL,			// 42 Address Prefix List
	kDNSType_DS,			// 43 Delegation Signer
	kDNSType_SSHFP,			// 44 SSH Key Fingerprint
	kDNSType_IPSECKEY,		// 45 IPSECKEY
	kDNSType_RRSIG,			// 46 RRSIG
	kDNSType_NSEC,			// 47 Denial of Existence
	kDNSType_DNSKEY,		// 48 DNSKEY
	kDNSType_DHCID,			// 49 DHCP Client Identifier
	kDNSType_NSEC3,			// 50 Hashed Authenticated Denial of Existence
	kDNSType_NSEC3PARAM,	// 51 Hashed Authenticated Denial of Existence

	kDNSType_HIP = 55,		// 55 Host Identity Protocol

	kDNSType_SPF = 99,		// 99 Sender Policy Framework for E-Mail
	kDNSType_UINFO,			// 100 IANA-Reserved
	kDNSType_UID,			// 101 IANA-Reserved
	kDNSType_GID,			// 102 IANA-Reserved
	kDNSType_UNSPEC,		// 103 IANA-Reserved

	kDNSType_TKEY = 249,	// 249 Transaction key
	kDNSType_TSIG,			// 250 Transaction signature
	kDNSType_IXFR,			// 251 Incremental zone transfer
	kDNSType_AXFR,			// 252 Transfer zone of authority
	kDNSType_MAILB,			// 253 Transfer mailbox records
	kDNSType_MAILA,			// 254 Transfer mail agent records
	kDNSQType_ANY			// Not a DNS type, but a DNS query type, meaning "all types"
	} DNS_TypeValues;

// ***************************************************************************
#if 0
#pragma mark -
#pragma mark - Simple types
#endif

// mDNS defines its own names for these common types to simplify portability across
// multiple platforms that may each have their own (different) names for these types.
typedef          int   mDNSBool;
typedef   signed char  mDNSs8;
typedef unsigned char  mDNSu8;
typedef   signed short mDNSs16;
typedef unsigned short mDNSu16;

// <http://gcc.gnu.org/onlinedocs/gcc-3.3.3/cpp/Common-Predefined-Macros.html> says
//   __LP64__ _LP64
//   These macros are defined, with value 1, if (and only if) the compilation is
//   for a target where long int and pointer both use 64-bits and int uses 32-bit.
// <http://www.intel.com/software/products/compilers/clin/docs/ug/lin1077.htm> says
//   Macro Name __LP64__ Value 1
// A quick Google search for "defined(__LP64__)" OR "#ifdef __LP64__" gives 2590 hits and
// a search for "#if __LP64__" gives only 12, so I think we'll go with the majority and use defined()
#if defined(_ILP64) || defined(__ILP64__)
typedef   signed int32 mDNSs32;
typedef unsigned int32 mDNSu32;
#elif defined(_LP64) || defined(__LP64__)
typedef   signed int   mDNSs32;
typedef unsigned int   mDNSu32;
#else
typedef   signed long  mDNSs32;
typedef unsigned long  mDNSu32;
//typedef   signed int mDNSs32;
//typedef unsigned int mDNSu32;
#endif

// To enforce useful type checking, we make mDNSInterfaceID be a pointer to a dummy struct
// This way, mDNSInterfaceIDs can be assigned, and compared with each other, but not with other types
// Declaring the type to be the typical generic "void *" would lack this type checking
typedef struct mDNSInterfaceID_dummystruct { void *dummy; } *mDNSInterfaceID;

// These types are for opaque two- and four-byte identifiers.
// The "NotAnInteger" fields of the unions allow the value to be conveniently passed around in a
// register for the sake of efficiency, and compared for equality or inequality, but don't forget --
// just because it is in a register doesn't mean it is an integer. Operations like greater than,
// less than, add, multiply, increment, decrement, etc., are undefined for opaque identifiers,
// and if you make the mistake of trying to do those using the NotAnInteger field, then you'll
// find you get code that doesn't work consistently on big-endian and little-endian machines.
#if defined(_WIN32)
 #pragma pack(push,2)
#endif
typedef       union { mDNSu8 b[ 2]; mDNSu16 NotAnInteger; } mDNSOpaque16;
typedef       union { mDNSu8 b[ 4]; mDNSu32 NotAnInteger; } mDNSOpaque32;
typedef packedunion { mDNSu8 b[ 6]; mDNSu16 w[3]; mDNSu32 l[1]; } mDNSOpaque48;
typedef       union { mDNSu8 b[ 8]; mDNSu16 w[4]; mDNSu32 l[2]; } mDNSOpaque64;
typedef       union { mDNSu8 b[16]; mDNSu16 w[8]; mDNSu32 l[4]; } mDNSOpaque128;
#if defined(_WIN32)
 #pragma pack(pop)
#endif

typedef mDNSOpaque16  mDNSIPPort;		// An IP port is a two-byte opaque identifier (not an integer)
typedef mDNSOpaque32  mDNSv4Addr;		// An IP address is a four-byte opaque identifier (not an integer)
typedef mDNSOpaque128 mDNSv6Addr;		// An IPv6 address is a 16-byte opaque identifier (not an integer)
typedef mDNSOpaque48  mDNSEthAddr;		// An Ethernet address is a six-byte opaque identifier (not an integer)

// Bit operations for opaque 64 bit quantity. Uses the 32 bit quantity(l[2]) to set and clear bits
#define mDNSNBBY 8
#define bit_set_opaque64(op64, index) (op64.l[((index))/(sizeof(mDNSu32) * mDNSNBBY)] |= (1 << ((index) % (sizeof(mDNSu32) * mDNSNBBY))))
#define bit_clr_opaque64(op64, index) (op64.l[((index))/(sizeof(mDNSu32) * mDNSNBBY)] &= ~(1 << ((index) % (sizeof(mDNSu32) * mDNSNBBY))))
#define bit_get_opaque64(op64, index) (op64.l[((index))/(sizeof(mDNSu32) * mDNSNBBY)] & (1 << ((index) % (sizeof(mDNSu32) * mDNSNBBY))))

enum
	{
	mDNSAddrType_None    = 0,
	mDNSAddrType_IPv4    = 4,
	mDNSAddrType_IPv6    = 6,
	mDNSAddrType_Unknown = ~0	// Special marker value used in known answer list recording
	};

enum
	{
	mDNSTransport_None = 0,
	mDNSTransport_UDP  = 1,
	mDNSTransport_TCP  = 2
	};

typedef struct
	{
	mDNSs32 type;
	union { mDNSv6Addr v6; mDNSv4Addr v4; } ip;
	} mDNSAddr;

enum { mDNSfalse = 0, mDNStrue = 1 };

#define mDNSNULL 0L

enum
	{
	mStatus_Waiting           = 1,
	mStatus_NoError           = 0,

	// mDNS return values are in the range FFFE FF00 (-65792) to FFFE FFFF (-65537)
	// The top end of the range (FFFE FFFF) is used for error codes;
	// the bottom end of the range (FFFE FF00) is used for non-error values;

	// Error codes:
	mStatus_UnknownErr                = -65537,		// First value: 0xFFFE FFFF
	mStatus_NoSuchNameErr             = -65538,
	mStatus_NoMemoryErr               = -65539,
	mStatus_BadParamErr               = -65540,
	mStatus_BadReferenceErr           = -65541,
	mStatus_BadStateErr               = -65542,
	mStatus_BadFlagsErr               = -65543,
	mStatus_UnsupportedErr            = -65544,
	mStatus_NotInitializedErr         = -65545,
	mStatus_NoCache                   = -65546,
	mStatus_AlreadyRegistered         = -65547,
	mStatus_NameConflict              = -65548,
	mStatus_Invalid                   = -65549,
	mStatus_Firewall                  = -65550,
	mStatus_Incompatible              = -65551,
	mStatus_BadInterfaceErr           = -65552,
	mStatus_Refused                   = -65553,
	mStatus_NoSuchRecord              = -65554,
	mStatus_NoAuth                    = -65555,
	mStatus_NoSuchKey                 = -65556,
	mStatus_NATTraversal              = -65557,
	mStatus_DoubleNAT                 = -65558,
	mStatus_BadTime                   = -65559,
	mStatus_BadSig                    = -65560,     // while we define this per RFC 2845, BIND 9 returns Refused for bad/missing signatures
	mStatus_BadKey                    = -65561,
	mStatus_TransientErr              = -65562,     // transient failures, e.g. sending packets shortly after a network transition or wake from sleep
	mStatus_ServiceNotRunning         = -65563,     // Background daemon not running
	mStatus_NATPortMappingUnsupported = -65564,     // NAT doesn't support NAT-PMP or UPnP
	mStatus_NATPortMappingDisabled    = -65565,     // NAT supports NAT-PMP or UPnP but it's disabled by the administrator
	mStatus_NoRouter                  = -65566,
	mStatus_PollingMode               = -65567,
	mStatus_Timeout                   = -65568,
	// -65568 to -65786 currently unused; available for allocation

	// tcp connection status
	mStatus_ConnPending       = -65787,
	mStatus_ConnFailed        = -65788,
	mStatus_ConnEstablished   = -65789,

	// Non-error values:
	mStatus_GrowCache         = -65790,
	mStatus_ConfigChanged     = -65791,
	mStatus_MemFree           = -65792		// Last value: 0xFFFE FF00
	// mStatus_MemFree is the last legal mDNS error code, at the end of the range allocated for mDNS
	};

typedef mDNSs32 mStatus;

// RFC 1034/1035 specify that a domain label consists of a length byte plus up to 63 characters
#define MAX_DOMAIN_LABEL 63
typedef struct { mDNSu8 c[ 64]; } domainlabel;		// One label: length byte and up to 63 characters

// RFC 1034/1035/2181 specify that a domain name (length bytes and data bytes) may be up to 255 bytes long,
// plus the terminating zero at the end makes 256 bytes total in the on-the-wire format.
#define MAX_DOMAIN_NAME 256
typedef struct { mDNSu8 c[256]; } domainname;		// Up to 256 bytes of length-prefixed domainlabels

typedef struct { mDNSu8 c[256]; } UTF8str255;		// Null-terminated C string

// The longest legal textual form of a DNS name is 1009 bytes, including the C-string terminating NULL at the end.
// Explanation:
// When a native domainname object is converted to printable textual form using ConvertDomainNameToCString(),
// non-printing characters are represented in the conventional DNS way, as '\ddd', where ddd is a three-digit decimal number.
// The longest legal domain name is 256 bytes, in the form of four labels as shown below:
// Length byte, 63 data bytes, length byte, 63 data bytes, length byte, 63 data bytes, length byte, 62 data bytes, zero byte.
// Each label is encoded textually as characters followed by a trailing dot.
// If every character has to be represented as a four-byte escape sequence, then this makes the maximum textual form four labels
// plus the C-string terminating NULL as shown below:
// 63*4+1 + 63*4+1 + 63*4+1 + 62*4+1 + 1 = 1009.
// Note that MAX_ESCAPED_DOMAIN_LABEL is not normally used: If you're only decoding a single label, escaping is usually not required.
// It is for domain names, where dots are used as label separators, that proper escaping is vital.
#define MAX_ESCAPED_DOMAIN_LABEL 254
#define MAX_ESCAPED_DOMAIN_NAME 1009

// MAX_REVERSE_MAPPING_NAME
// For IPv4: "123.123.123.123.in-addr.arpa."  30 bytes including terminating NUL
// For IPv6: "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."  74 bytes including terminating NUL

#define MAX_REVERSE_MAPPING_NAME_V4 30
#define MAX_REVERSE_MAPPING_NAME_V6 74
#define MAX_REVERSE_MAPPING_NAME    74

// Most records have a TTL of 75 minutes, so that their 80% cache-renewal query occurs once per hour.
// For records containing a hostname (in the name on the left, or in the rdata on the right),
// like A, AAAA, reverse-mapping PTR, and SRV, we use a two-minute TTL by default, because we don't want
// them to hang around for too long in the cache if the host in question crashes or otherwise goes away.

#define kStandardTTL (3600UL * 100 / 80)
#define kHostNameTTL 120UL

// Some applications want to register their SRV records with a lower ttl so that in case the server
// using a dynamic port number restarts, the clients will not have stale information for more than
// 10 seconds

#define kHostNameSmallTTL 10UL

// Multicast DNS uses announcements (gratuitous responses) to update peer caches.
// This means it is feasible to use relatively larger TTL values than we might otherwise
// use, because we have a cache coherency protocol to keep the peer caches up to date.
// With Unicast DNS, once an authoritative server gives a record with a certain TTL value to a client
// or caching server, that client or caching server is entitled to hold onto the record until its TTL
// expires, and has no obligation to contact the authoritative server again until that time arrives.
// This means that whereas Multicast DNS can use announcements to pre-emptively update stale data
// before it would otherwise have expired, standard Unicast DNS (not using LLQs) has no equivalent
// mechanism, and TTL expiry is the *only* mechanism by which stale data gets deleted. Because of this,
// we currently limit the TTL to ten seconds in such cases where no dynamic cache updating is possible.
#define kStaticCacheTTL 10

#define DefaultTTLforRRType(X) (((X) == kDNSType_A || (X) == kDNSType_AAAA || (X) == kDNSType_SRV) ? kHostNameTTL : kStandardTTL)

typedef struct AuthRecord_struct AuthRecord;
typedef struct ServiceRecordSet_struct ServiceRecordSet;
typedef struct CacheRecord_struct CacheRecord;
typedef struct CacheGroup_struct CacheGroup;
typedef struct AuthGroup_struct AuthGroup;
typedef struct DNSQuestion_struct DNSQuestion;
typedef struct ZoneData_struct ZoneData;
typedef struct mDNS_struct mDNS;
typedef struct mDNS_PlatformSupport_struct mDNS_PlatformSupport;
typedef struct NATTraversalInfo_struct NATTraversalInfo;

// Structure to abstract away the differences between TCP/SSL sockets, and one for UDP sockets
// The actual definition of these structures appear in the appropriate platform support code
typedef struct TCPSocket_struct TCPSocket;
typedef struct UDPSocket_struct UDPSocket;

// ***************************************************************************
#if 0
#pragma mark -
#pragma mark - DNS Message structures
#endif

#define mDNS_numZones   numQuestions
#define mDNS_numPrereqs numAnswers
#define mDNS_numUpdates numAuthorities

typedef packedstruct
	{
	mDNSOpaque16 id;
	mDNSOpaque16 flags;
	mDNSu16 numQuestions;
	mDNSu16 numAnswers;
	mDNSu16 numAuthorities;
	mDNSu16 numAdditionals;
	} DNSMessageHeader;

// We can send and receive packets up to 9000 bytes (Ethernet Jumbo Frame size, if that ever becomes widely used)
// However, in the normal case we try to limit packets to 1500 bytes so that we don't get IP fragmentation on standard Ethernet
// 40 (IPv6 header) + 8 (UDP header) + 12 (DNS message header) + 1440 (DNS message body) = 1500 total
#define AbsoluteMaxDNSMessageData 8940
#define NormalMaxDNSMessageData 1440
typedef packedstruct
	{
	DNSMessageHeader h;						// Note: Size 12 bytes
	mDNSu8 data[AbsoluteMaxDNSMessageData];	// 40 (IPv6) + 8 (UDP) + 12 (DNS header) + 8940 (data) = 9000
	} DNSMessage;

typedef struct tcpInfo_t
	{
	mDNS             *m;
	TCPSocket        *sock;
	DNSMessage        request;
	int               requestLen;
	DNSQuestion      *question;   // For queries
	AuthRecord       *rr;         // For record updates
	mDNSAddr          Addr;
	mDNSIPPort        Port;
	mDNSIPPort        SrcPort;
	DNSMessage       *reply;
	mDNSu16           replylen;
	unsigned long     nread;
	int               numReplies;
	} tcpInfo_t;

// ***************************************************************************
#if 0
#pragma mark -
#pragma mark - Other Packet Format Structures
#endif

typedef packedstruct
	{
	mDNSEthAddr  dst;
	mDNSEthAddr  src;
	mDNSOpaque16 ethertype;
	} EthernetHeader;		// 14 bytes

typedef packedstruct
	{
	mDNSOpaque16 hrd;
	mDNSOpaque16 pro;
	mDNSu8       hln;
	mDNSu8       pln;
	mDNSOpaque16 op;
	mDNSEthAddr  sha;
	mDNSv4Addr   spa;
	mDNSEthAddr  tha;
	mDNSv4Addr   tpa;
	} ARP_EthIP;			// 28 bytes

typedef packedstruct
	{
	mDNSu8       vlen;
	mDNSu8       tos;
	mDNSu16      totlen;
	mDNSOpaque16 id;
	mDNSOpaque16 flagsfrags;
	mDNSu8       ttl;
	mDNSu8       protocol;	// Payload type: 0x06 = TCP, 0x11 = UDP
	mDNSu16      checksum;
	mDNSv4Addr   src;
	mDNSv4Addr   dst;
	} IPv4Header;			// 20 bytes

typedef packedstruct
	{
	mDNSu32      vcf;		// Version, Traffic Class, Flow Label
	mDNSu16      len;		// Payload Length
	mDNSu8       pro;		// Type of next header: 0x06 = TCP, 0x11 = UDP, 0x3A = ICMPv6
	mDNSu8       ttl;		// Hop Limit
	mDNSv6Addr   src;
	mDNSv6Addr   dst;
	} IPv6Header;			// 40 bytes

typedef packedstruct
	{
	mDNSv6Addr   src;
	mDNSv6Addr   dst;
	mDNSOpaque32 len;
	mDNSOpaque32 pro;
	} IPv6PseudoHeader;		// 40 bytes

typedef union
	{
	mDNSu8       bytes[20];
	ARP_EthIP    arp;
	IPv4Header   v4;
	IPv6Header   v6;
	} NetworkLayerPacket;

typedef packedstruct
	{
	mDNSIPPort   src;
	mDNSIPPort   dst;
	mDNSu32      seq;
	mDNSu32      ack;
	mDNSu8       offset;
	mDNSu8       flags;
	mDNSu16      window;
	mDNSu16      checksum;
	mDNSu16      urgent;
	} TCPHeader;			// 20 bytes; IP protocol type 0x06

typedef packedstruct
	{
	mDNSIPPort   src;
	mDNSIPPort   dst;
	mDNSu16      len;		// Length including UDP header (i.e. minimum value is 8 bytes)
	mDNSu16      checksum;
	} UDPHeader;			// 8 bytes; IP protocol type 0x11

typedef packedstruct
	{
	mDNSu8       type;		// 0x87 == Neighbor Solicitation, 0x88 == Neighbor Advertisement
	mDNSu8       code;
	mDNSu16      checksum;
	mDNSu32      flags_res;	// R/S/O flags and reserved bits
	mDNSv6Addr   target;
	// Typically 8 bytes of options are also present
	} IPv6NDP;				// 24 bytes or more; IP protocol type 0x3A

#define NDP_Sol 0x87
#define NDP_Adv 0x88

#define NDP_Router    0x80
#define NDP_Solicited 0x40
#define NDP_Override  0x20

#define NDP_SrcLL 1
#define NDP_TgtLL 2

typedef union
	{
	mDNSu8       bytes[20];
	TCPHeader    tcp;
	UDPHeader    udp;
	IPv6NDP      ndp;
	} TransportLayerPacket;

typedef packedstruct
	{
	mDNSOpaque64 InitiatorCookie;
	mDNSOpaque64 ResponderCookie;
	mDNSu8       NextPayload;
	mDNSu8       Version;
	mDNSu8       ExchangeType;
	mDNSu8       Flags;
	mDNSOpaque32 MessageID;
	mDNSu32      Length;
	} IKEHeader;			// 28 bytes

// ***************************************************************************
#if 0
#pragma mark -
#pragma mark - Resource Record structures
#endif

// Authoritative Resource Records:
// There are four basic types: Shared, Advisory, Unique, Known Unique

// * Shared Resource Records do not have to be unique
// -- Shared Resource Records are used for DNS-SD service PTRs
// -- It is okay for several hosts to have RRs with the same name but different RDATA
// -- We use a random delay on responses to reduce collisions when all the hosts respond to the same query
// -- These RRs typically have moderately high TTLs (e.g. one hour)
// -- These records are announced on startup and topology changes for the benefit of passive listeners
// -- These records send a goodbye packet when deregistering
//
// * Advisory Resource Records are like Shared Resource Records, except they don't send a goodbye packet
//
// * Unique Resource Records should be unique among hosts within any given mDNS scope
// -- The majority of Resource Records are of this type
// -- If two entities on the network have RRs with the same name but different RDATA, this is a conflict
// -- Responses may be sent immediately, because only one host should be responding to any particular query
// -- These RRs typically have low TTLs (e.g. a few minutes)
// -- On startup and after topology changes, a host issues queries to verify uniqueness

// * Known Unique Resource Records are treated like Unique Resource Records, except that mDNS does
// not have to verify their uniqueness because this is already known by other means (e.g. the RR name
// is derived from the host's IP or Ethernet address, which is already known to be a unique identifier).

// Summary of properties of different record types:
// Probe?    Does this record type send probes before announcing?
// Conflict? Does this record type react if we observe an apparent conflict?
// Goodbye?  Does this record type send a goodbye packet on departure?
//
//               Probe? Conflict? Goodbye? Notes
// Unregistered                            Should not appear in any list (sanity check value)
// Shared         No      No       Yes     e.g. Service PTR record
// Deregistering  No      No       Yes     Shared record about to announce its departure and leave the list
// Advisory       No      No       No
// Unique         Yes     Yes      No      Record intended to be unique -- will probe to verify
// Verified       Yes     Yes      No      Record has completed probing, and is verified unique
// KnownUnique    No      Yes      No      Record is assumed by other means to be unique

// Valid lifecycle of a record:
// Unregistered ->                   Shared      -> Deregistering -(goodbye)-> Unregistered
// Unregistered ->                   Advisory                               -> Unregistered
// Unregistered -> Unique -(probe)-> Verified                               -> Unregistered
// Unregistered ->                   KnownUnique                            -> Unregistered

// Each Authoritative kDNSRecordType has only one bit set. This makes it easy to quickly see if a record
// is one of a particular set of types simply by performing the appropriate bitwise masking operation.

// Cache Resource Records (received from the network):
// There are four basic types: Answer, Unique Answer, Additional, Unique Additional
// Bit 7 (the top bit) of kDNSRecordType is always set for Cache Resource Records; always clear for Authoritative Resource Records
// Bit 6 (value 0x40) is set for answer records; clear for authority/additional records
// Bit 5 (value 0x20) is set for records received with the kDNSClass_UniqueRRSet

enum
	{
	kDNSRecordTypeUnregistered     = 0x00,	// Not currently in any list
	kDNSRecordTypeDeregistering    = 0x01,	// Shared record about to announce its departure and leave the list

	kDNSRecordTypeUnique           = 0x02,	// Will become a kDNSRecordTypeVerified when probing is complete

	kDNSRecordTypeAdvisory         = 0x04,	// Like Shared, but no goodbye packet
	kDNSRecordTypeShared           = 0x08,	// Shared means record name does not have to be unique -- use random delay on responses

	kDNSRecordTypeVerified         = 0x10,	// Unique means mDNS should check that name is unique (and then send immediate responses)
	kDNSRecordTypeKnownUnique      = 0x20,	// Known Unique means mDNS can assume name is unique without checking
	                                        // For Dynamic Update records, Known Unique means the record must already exist on the server.
	kDNSRecordTypeUniqueMask       = (kDNSRecordTypeUnique | kDNSRecordTypeVerified | kDNSRecordTypeKnownUnique),
	kDNSRecordTypeActiveSharedMask = (kDNSRecordTypeAdvisory         | kDNSRecordTypeShared),
	kDNSRecordTypeActiveUniqueMask = (kDNSRecordTypeVerified         | kDNSRecordTypeKnownUnique),
	kDNSRecordTypeActiveMask       = (kDNSRecordTypeActiveSharedMask | kDNSRecordTypeActiveUniqueMask),

	kDNSRecordTypePacketAdd        = 0x80,	// Received in the Additional  Section of a DNS Response
	kDNSRecordTypePacketAddUnique  = 0x90,	// Received in the Additional  Section of a DNS Response with kDNSClass_UniqueRRSet set
	kDNSRecordTypePacketAuth       = 0xA0,	// Received in the Authorities Section of a DNS Response
	kDNSRecordTypePacketAuthUnique = 0xB0,	// Received in the Authorities Section of a DNS Response with kDNSClass_UniqueRRSet set
	kDNSRecordTypePacketAns        = 0xC0,	// Received in the Answer      Section of a DNS Response
	kDNSRecordTypePacketAnsUnique  = 0xD0,	// Received in the Answer      Section of a DNS Response with kDNSClass_UniqueRRSet set

	kDNSRecordTypePacketNegative   = 0xF0,	// Pseudo-RR generated to cache non-existence results like NXDomain

	kDNSRecordTypePacketUniqueMask = 0x10	// True for PacketAddUnique, PacketAnsUnique, PacketAuthUnique, kDNSRecordTypePacketNegative
	};

typedef packedstruct { mDNSu16 priority; mDNSu16 weight; mDNSIPPort port; domainname target;   } rdataSRV;
typedef packedstruct { mDNSu16 preference;                                domainname exchange; } rdataMX;
typedef packedstruct { domainname mbox; domainname txt;                                        } rdataRP;
typedef packedstruct { mDNSu16 preference; domainname map822; domainname mapx400;              } rdataPX;

typedef packedstruct
	{
	domainname mname;
	domainname rname;
	mDNSs32 serial;		// Modular counter; increases when zone changes
	mDNSu32 refresh;	// Time in seconds that a slave waits after successful replication of the database before it attempts replication again
	mDNSu32 retry;		// Time in seconds that a slave waits after an unsuccessful replication attempt before it attempts replication again
	mDNSu32 expire;		// Time in seconds that a slave holds on to old data while replication attempts remain unsuccessful
	mDNSu32 min;		// Nominally the minimum record TTL for this zone, in seconds; also used for negative caching.
	} rdataSOA;

// EDNS Option Code registrations are recorded in the "DNS EDNS0 Options" section of
// <http://www.iana.org/assignments/dns-parameters>

#define kDNSOpt_LLQ   1
#define kDNSOpt_Lease 2
#define kDNSOpt_NSID  3
#define kDNSOpt_Owner 4

typedef struct
	{
	mDNSu16      vers;
	mDNSu16      llqOp;
	mDNSu16      err;	// Or UDP reply port, in setup request
	// Note: In the in-memory form, there's typically a two-byte space here, so that the following 64-bit id is word-aligned
	mDNSOpaque64 id;
	mDNSu32      llqlease;
	} LLQOptData;

typedef struct
	{
	mDNSu8       vers;		// Version number of this Owner OPT record
	mDNSs8       seq;		// Sleep/wake epoch
	mDNSEthAddr  HMAC;		// Host's primary identifier (e.g. MAC of on-board Ethernet)
	mDNSEthAddr  IMAC;		// Interface's MAC address (if different to primary MAC)
	mDNSOpaque48 password;	// Optional password
	} OwnerOptData;

// Note: rdataOPT format may be repeated an arbitrary number of times in a single resource record
typedef packedstruct
	{
	mDNSu16 opt;
	mDNSu16 optlen;
	union { LLQOptData llq; mDNSu32 updatelease; OwnerOptData owner; } u;
	} rdataOPT;

// Space needed to put OPT records into a packet:
// Header      11 bytes (name 1, type 2, class 2, TTL 4, length 2)
// LLQ rdata   18 bytes (opt 2, len 2, vers 2, op 2, err 2, id 8, lease 4)
// Lease rdata  8 bytes (opt 2, len 2, lease 4)
// Owner rdata 12-24    (opt 2, len 2, owner 8-20)

#define DNSOpt_Header_Space                 11
#define DNSOpt_LLQData_Space               (4 + 2 + 2 + 2 + 8 + 4)
#define DNSOpt_LeaseData_Space             (4 + 4)
#define DNSOpt_OwnerData_ID_Space          (4 + 2 + 6)
#define DNSOpt_OwnerData_ID_Wake_Space     (4 + 2 + 6 + 6)
#define DNSOpt_OwnerData_ID_Wake_PW4_Space (4 + 2 + 6 + 6 + 4)
#define DNSOpt_OwnerData_ID_Wake_PW6_Space (4 + 2 + 6 + 6 + 6)

#define ValidOwnerLength(X) (	(X) == DNSOpt_OwnerData_ID_Space          - 4 || \
								(X) == DNSOpt_OwnerData_ID_Wake_Space     - 4 || \
								(X) == DNSOpt_OwnerData_ID_Wake_PW4_Space - 4 || \
								(X) == DNSOpt_OwnerData_ID_Wake_PW6_Space - 4    )

#define DNSOpt_Owner_Space(A,B) (mDNSSameEthAddress((A),(B)) ? DNSOpt_OwnerData_ID_Space : DNSOpt_OwnerData_ID_Wake_Space)

#define DNSOpt_Data_Space(O) (                                  \
	(O)->opt == kDNSOpt_LLQ   ? DNSOpt_LLQData_Space   :        \
	(O)->opt == kDNSOpt_Lease ? DNSOpt_LeaseData_Space :        \
	(O)->opt == kDNSOpt_Owner ? DNSOpt_Owner_Space(&(O)->u.owner.HMAC, &(O)->u.owner.IMAC) : 0x10000)

// A maximal NSEC record is:
//   256 bytes domainname 'nextname'
// + 256 * 34 = 8704 bytes of bitmap data
// = 8960 bytes total
// For now we only support NSEC records encoding DNS types 0-255 and ignore the nextname (we always set it to be the same as the rrname),
// which gives us a fixed in-memory size of 32 bytes (256 bits)
typedef struct
	{
	mDNSu8 bitmap[32];
	} rdataNSEC;

// StandardAuthRDSize is 264 (256+8), which is large enough to hold a maximum-sized SRV record (6 + 256 bytes)
// MaximumRDSize is 8K the absolute maximum we support (at least for now)
#define StandardAuthRDSize 264
#define MaximumRDSize 8192

// InlineCacheRDSize is 68
// Records received from the network with rdata this size or less have their rdata stored right in the CacheRecord object
// Records received from the network with rdata larger than this have additional storage allocated for the rdata
// A quick unscientific sample from a busy network at Apple with lots of machines revealed this:
// 1461 records in cache
// 292 were one-byte TXT records
// 136 were four-byte A records
// 184 were sixteen-byte AAAA records
// 780 were various PTR, TXT and SRV records from 12-64 bytes
// Only 69 records had rdata bigger than 64 bytes
// Note that since CacheRecord object and a CacheGroup object are allocated out of the same pool, it's sensible to
// have them both be the same size. Making one smaller without making the other smaller won't actually save any memory.
#define InlineCacheRDSize 68

// On 64-bit, the pointers in a CacheRecord are bigger, and that creates 8 bytes more space for the name in a CacheGroup
#if ENABLE_MULTI_PACKET_QUERY_SNOOPING
	#if defined(_ILP64) || defined(__ILP64__) || defined(_LP64) || defined(__LP64__) || defined(_WIN64)
	#define InlineCacheGroupNameSize 160
	#else
	#define InlineCacheGroupNameSize 148
	#endif
#else
	#if defined(_ILP64) || defined(__ILP64__) || defined(_LP64) || defined(__LP64__) || defined(_WIN64)
	#define InlineCacheGroupNameSize 144
	#else
	#define InlineCacheGroupNameSize 132
	#endif
#endif

// The RDataBody union defines the common rdata types that fit into our 264-byte limit
typedef union
	{
	mDNSu8      data[StandardAuthRDSize];
	mDNSv4Addr  ipv4;		// For 'A' record
	domainname  name;		// For PTR, NS, CNAME, DNAME
	UTF8str255  txt;
	rdataMX     mx;
	mDNSv6Addr  ipv6;		// For 'AAAA' record
	rdataSRV    srv;
	rdataOPT    opt[2];		// For EDNS0 OPT record; RDataBody may contain multiple variable-length rdataOPT objects packed together
	rdataNSEC   nsec;
	} RDataBody;

// The RDataBody2 union is the same as above, except it includes fields for the larger types like soa, rp, px
typedef union
	{
	mDNSu8      data[StandardAuthRDSize];
	mDNSv4Addr  ipv4;		// For 'A' record
	domainname  name;		// For PTR, NS, CNAME, DNAME
	rdataSOA    soa;		// This is large; not included in the normal RDataBody definition
	UTF8str255  txt;
	rdataMX     mx;
	rdataRP     rp;			// This is large; not included in the normal RDataBody definition
	rdataPX     px;			// This is large; not included in the normal RDataBody definition
	mDNSv6Addr  ipv6;		// For 'AAAA' record
	rdataSRV    srv;
	rdataOPT    opt[2];		// For EDNS0 OPT record; RDataBody may contain multiple variable-length rdataOPT objects packed together
	rdataNSEC   nsec;
	} RDataBody2;

typedef struct
	{
	mDNSu16    MaxRDLength;	// Amount of storage allocated for rdata (usually sizeof(RDataBody))
	mDNSu16    padding;		// So that RDataBody is aligned on 32-bit boundary
	RDataBody  u;
	} RData;

// sizeofRDataHeader should be 4 bytes
#define sizeofRDataHeader (sizeof(RData) - sizeof(RDataBody))

// RData_small is a smaller version of the RData object, used for inline data storage embedded in a CacheRecord_struct
typedef struct
	{
	mDNSu16    MaxRDLength;	// Storage allocated for data (may be greater than InlineCacheRDSize if additional storage follows this object)
	mDNSu16    padding;		// So that data is aligned on 32-bit boundary
	mDNSu8     data[InlineCacheRDSize];
	} RData_small;

// Note: Within an mDNSRecordCallback mDNS all API calls are legal except mDNS_Init(), mDNS_Exit(), mDNS_Execute()
typedef void mDNSRecordCallback(mDNS *const m, AuthRecord *const rr, mStatus result);

// Note:
// Restrictions: An mDNSRecordUpdateCallback may not make any mDNS API calls.
// The intent of this callback is to allow the client to free memory, if necessary.
// The internal data structures of the mDNS code may not be in a state where mDNS API calls may be made safely.
typedef void mDNSRecordUpdateCallback(mDNS *const m, AuthRecord *const rr, RData *OldRData, mDNSu16 OldRDLen);

// ***************************************************************************
#if 0
#pragma mark -
#pragma mark - NAT Traversal structures and constants
#endif

#define NATMAP_MAX_RETRY_INTERVAL    ((mDNSPlatformOneSecond * 60) * 15)    // Max retry interval is 15 minutes
#define NATMAP_MIN_RETRY_INTERVAL     (mDNSPlatformOneSecond * 2)           // Min retry interval is 2 seconds
#define NATMAP_INIT_RETRY             (mDNSPlatformOneSecond / 4)           // start at 250ms w/ exponential decay
#define NATMAP_DEFAULT_LEASE          (60 * 60 * 2)                         // 2 hour lease life in seconds
#define NATMAP_VERS 0

typedef enum
	{
	NATOp_AddrRequest    = 0,
	NATOp_MapUDP         = 1,
	NATOp_MapTCP         = 2,

	NATOp_AddrResponse   = 0x80 | 0,
	NATOp_MapUDPResponse = 0x80 | 1,
	NATOp_MapTCPResponse = 0x80 | 2,
	} NATOp_t;

enum
	{
	NATErr_None    = 0,
	NATErr_Vers    = 1,
	NATErr_Refused = 2,
	NATErr_NetFail = 3,
	NATErr_Res     = 4,
	NATErr_Opcode  = 5
	};

typedef mDNSu16 NATErr_t;

typedef packedstruct
	{
	mDNSu8 vers;
	mDNSu8 opcode;
	} NATAddrRequest;

typedef packedstruct
	{
	mDNSu8     vers;
	mDNSu8     opcode;
	mDNSu16    err;
	mDNSu32    upseconds;		// Time since last NAT engine reboot, in seconds
	mDNSv4Addr ExtAddr;
	} NATAddrReply;

typedef packedstruct
	{
	mDNSu8 vers;
	mDNSu8 opcode;
	mDNSOpaque16 unused;
	mDNSIPPort intport;
	mDNSIPPort extport;
	mDNSu32    NATReq_lease;
	} NATPortMapRequest;

typedef packedstruct
	{
	mDNSu8     vers;
	mDNSu8     opcode;
	mDNSu16    err;
	mDNSu32    upseconds;		// Time since last NAT engine reboot, in seconds
	mDNSIPPort intport;
	mDNSIPPort extport;
	mDNSu32    NATRep_lease;
	} NATPortMapReply;

typedef enum
	{
	LNTDiscoveryOp      = 1,
	LNTExternalAddrOp   = 2,
	LNTPortMapOp        = 3,
	LNTPortMapDeleteOp  = 4
	} LNTOp_t;

#define LNT_MAXBUFSIZE 8192
typedef struct tcpLNTInfo_struct tcpLNTInfo;
struct tcpLNTInfo_struct
	{
	tcpLNTInfo       *next;
	mDNS             *m;
	NATTraversalInfo *parentNATInfo;	// pointer back to the parent NATTraversalInfo
	TCPSocket        *sock;
	LNTOp_t           op;				// operation performed using this connection
	mDNSAddr          Address;			// router address
	mDNSIPPort        Port;				// router port
	mDNSu8           *Request;			// xml request to router
	int               requestLen;
	mDNSu8           *Reply;			// xml reply from router
	int               replyLen;
	unsigned long     nread;			// number of bytes read so far
	int               retries;			// number of times we've tried to do this port mapping
	};

typedef void (*NATTraversalClientCallback)(mDNS *m, NATTraversalInfo *n);

// if m->timenow <  ExpiryTime then we have an active mapping, and we'll renew halfway to expiry
// if m->timenow >= ExpiryTime then our mapping has expired, and we're trying to create one

struct NATTraversalInfo_struct
	{
	// Internal state fields. These are used internally by mDNSCore; the client layer needn't be concerned with them.
	NATTraversalInfo           *next;

	mDNSs32                     ExpiryTime;			// Time this mapping expires, or zero if no mapping
	mDNSs32                     retryInterval;		// Current interval, between last packet we sent and the next one
	mDNSs32                     retryPortMap;		// If Protocol is nonzero, time to send our next mapping packet
	mStatus                     NewResult;			// New error code; will be copied to Result just prior to invoking callback

#ifdef _LEGACY_NAT_TRAVERSAL_
	tcpLNTInfo                  tcpInfo;			// Legacy NAT traversal (UPnP) TCP connection
#endif

	// Result fields: When the callback is invoked these fields contain the answers the client is looking for
	// When the callback is invoked ExternalPort is *usually* set to be the same the same as RequestedPort, except:
	// (a) When we're behind a NAT gateway with port mapping disabled, ExternalPort is reported as zero to
	//     indicate that we don't currently have a working mapping (but RequestedPort retains the external port
	//     we'd like to get, the next time we meet an accomodating NAT gateway willing to give us one).
	// (b) When we have a routable non-RFC1918 address, we don't *need* a port mapping, so ExternalPort
	//     is reported as the same as our InternalPort, since that is effectively our externally-visible port too.
	//     Again, RequestedPort retains the external port we'd like to get the next time we find ourself behind a NAT gateway.
	// To improve stability of port mappings, RequestedPort is updated any time we get a successful
	// mapping response from the NAT-PMP or UPnP gateway. For example, if we ask for port 80, and
	// get assigned port 81, then thereafter we'll contine asking for port 81.
	mDNSInterfaceID             InterfaceID;
	mDNSv4Addr                  ExternalAddress;	// Initially set to onesIPv4Addr, until first callback
	mDNSIPPort                  ExternalPort;
	mDNSu32                     Lifetime;
	mStatus                     Result;

	// Client API fields: The client must set up these fields *before* making any NAT traversal API calls
	mDNSu8                      Protocol;			// NATOp_MapUDP or NATOp_MapTCP, or zero if just requesting the external IP address
	mDNSIPPort                  IntPort;			// Client's internal port number (doesn't change)
	mDNSIPPort                  RequestedPort;		// Requested external port; may be updated with actual value assigned by gateway
	mDNSu32                     NATLease;			// Requested lifetime in seconds (doesn't change)
	NATTraversalClientCallback  clientCallback;
	void                       *clientContext;
	};

enum
	{
	DNSServer_Untested = 0,
	DNSServer_Passed   = 1,
	DNSServer_Failed   = 2,
	DNSServer_Disabled = 3
	};

enum
	{
	DNSServer_FlagDelete = 1,
	DNSServer_FlagNew    = 2
	};

enum
	{
	McastResolver_FlagDelete = 1,
	McastResolver_FlagNew    = 2
	};

typedef struct McastResolver
	{
	struct McastResolver *next;
	mDNSInterfaceID interface;
	mDNSu32         flags;		// Set when we're planning to delete this from the list
	domainname      domain;
	mDNSu32         timeout;	// timeout value for questions
	} McastResolver;

typedef struct DNSServer
	{
	struct DNSServer *next;
	mDNSInterfaceID interface;	// For specialized uses; we can have DNS servers reachable over specific interfaces
	mDNSAddr        addr;
	mDNSIPPort      port;
	mDNSOpaque16    testid;
	mDNSu32         flags;		// Set when we're planning to delete this from the list
	mDNSu32         teststate;	// Have we sent bug-detection query to this server?
	mDNSs32         lasttest;	// Time we sent last bug-detection query to this server
	domainname      domain;		// name->server matching for "split dns"
	mDNSs32			penaltyTime; // amount of time this server is penalized
	mDNSBool		scoped;		// interface should be matched against question only
								// if scoped is set
	mDNSu32			timeout;	// timeout value for questions
	} DNSServer;

typedef struct							// Size is 36 bytes when compiling for 32-bit; 48 when compiling for 64-bit
	{
	mDNSu8           RecordType;		// See enum above
	mDNSu16          rrtype;
	mDNSu16          rrclass;
	mDNSu32          rroriginalttl;		// In seconds
	mDNSu16          rdlength;			// Size of the raw rdata, in bytes, in the on-the-wire format
										// (In-memory storage may be larger, for structures containing 'holes', like SOA,
										// or smaller, for NSEC where we don't bother storing the nextname field)
	mDNSu16          rdestimate;		// Upper bound on on-the-wire size of rdata after name compression
	mDNSu32          namehash;			// Name-based (i.e. case-insensitive) hash of name
	mDNSu32          rdatahash;			// For rdata containing domain name (e.g. PTR, SRV, CNAME etc.), case-insensitive name hash
										// else, for all other rdata, 32-bit hash of the raw rdata
										// Note: This requirement is important. Various routines like AddAdditionalsToResponseList(),
										// ReconfirmAntecedents(), etc., use rdatahash as a pre-flight check to see
										// whether it's worth doing a full SameDomainName() call. If the rdatahash
										// is not a correct case-insensitive name hash, they'll get false negatives.

	// Grouping pointers together at the end of the structure improves the memory layout efficiency
	mDNSInterfaceID  InterfaceID;		// Set if this RR is specific to one interface
										// For records received off the wire, InterfaceID is *always* set to the receiving interface
										// For our authoritative records, InterfaceID is usually zero, except for those few records
										// that are interface-specific (e.g. address records, especially linklocal addresses)
	const domainname *name;
	RData           *rdata;				// Pointer to storage for this rdata
	DNSServer       *rDNSServer;		// Unicast DNS server authoritative for this entry;null for multicast
	} ResourceRecord;

// Unless otherwise noted, states may apply to either independent record registrations or service registrations
typedef enum
	{
	regState_Zero              = 0,
	regState_Pending           = 1,     // update sent, reply not received
	regState_Registered        = 2,     // update sent, reply received
	regState_DeregPending      = 3,     // dereg sent, reply not received
	regState_Unregistered      = 4,     // not in any list
	regState_Refresh           = 5,     // outstanding refresh (or target change) message
	regState_NATMap            = 6,     // establishing NAT port mapping
	regState_UpdatePending     = 7,     // update in flight as result of mDNS_Update call
	regState_NoTarget          = 8,     // SRV Record registration pending registration of hostname
	regState_NATError          = 9     // unable to complete NAT traversal
	} regState_t;

enum
	{
	Target_Manual = 0,
	Target_AutoHost = 1,
	Target_AutoHostAndNATMAP = 2
	};

typedef enum
	{
	mergeState_Zero = 0,
	mergeState_DontMerge = 1  // Set on fatal error conditions to disable merging
	} mergeState_t;

struct AuthGroup_struct				// Header object for a list of AuthRecords with the same name
	{
	AuthGroup      *next;				// Next AuthGroup object in this hash table bucket
	mDNSu32         namehash;			// Name-based (i.e. case insensitive) hash of name
	AuthRecord     *members;			// List of CacheRecords with this same name
	AuthRecord    **rrauth_tail;		// Tail end of that list
	domainname     *name;				// Common name for all AuthRecords in this list
	AuthRecord     *NewLocalOnlyRecords;
	// Size to here is 20 bytes when compiling 32-bit; 40 bytes when compiling 64-bit
	mDNSu8          namestorage[InlineCacheGroupNameSize];
	};

#define AUTH_HASH_SLOTS 499
#define FORALL_AUTHRECORDS(SLOT,AG,AR)                           	\
	for ((SLOT) = 0; (SLOT) < AUTH_HASH_SLOTS; (SLOT)++)         	\
		for ((AG)=m->rrauth.rrauth_hash[(SLOT)]; (AG); (AG)=(AG)->next) \
			for ((AR) = (AG)->members; (AR); (AR)=(AR)->next)

typedef union AuthEntity_union AuthEntity;
union AuthEntity_union { AuthEntity *next; AuthGroup ag; };
typedef struct {
	mDNSu32 rrauth_size;				// Total number of available auth entries
	mDNSu32 rrauth_totalused;			// Number of auth entries currently occupied
	mDNSu32 rrauth_report;
	mDNSu8  rrauth_lock;				// For debugging: Set at times when these lists may not be modified
	AuthEntity *rrauth_free;
	AuthGroup *rrauth_hash[AUTH_HASH_SLOTS];
}AuthHash;

// AuthRecordAny includes mDNSInterface_Any and interface specific auth records (anything
// other than P2P or LocalOnly)
typedef enum
	{
	AuthRecordAny, 				// registered for *Any, NOT including P2P interfaces
	AuthRecordAnyIncludeP2P, 	// registered for *Any, including P2P interfaces
	AuthRecordLocalOnly,
	AuthRecordP2P				// discovered over D2D/P2P framework
	} AuthRecType;

struct AuthRecord_struct
	{
	// For examples of how to set up this structure for use in mDNS_Register(),
	// see mDNS_AdvertiseInterface() or mDNS_RegisterService().
	// Basically, resrec and persistent metadata need to be set up before calling mDNS_Register().
	// mDNS_SetupResourceRecord() is avaliable as a helper routine to set up most fields to sensible default values for you

	AuthRecord     *next;				// Next in list; first element of structure for efficiency reasons
	// Field Group 1: Common ResourceRecord fields
	ResourceRecord  resrec;				// 36 bytes when compiling for 32-bit; 48 when compiling for 64-bit

	// Field Group 2: Persistent metadata for Authoritative Records
	AuthRecord     *Additional1;		// Recommended additional record to include in response (e.g. SRV for PTR record)
	AuthRecord     *Additional2;		// Another additional (e.g. TXT for PTR record)
	AuthRecord     *DependentOn;		// This record depends on another for its uniqueness checking
	AuthRecord     *RRSet;				// This unique record is part of an RRSet
	mDNSRecordCallback *RecordCallback;	// Callback function to call for state changes, and to free memory asynchronously on deregistration
	void           *RecordContext;		// Context parameter for the callback function
	mDNSu8          AutoTarget;			// Set if the target of this record (PTR, CNAME, SRV, etc.) is our host name
	mDNSu8          AllowRemoteQuery;	// Set if we allow hosts not on the local link to query this record
	mDNSu8          ForceMCast;			// Set by client to advertise solely via multicast, even for apparently unicast names

	OwnerOptData    WakeUp;				// WakeUp.HMAC.l[0] nonzero indicates that this is a Sleep Proxy record
	mDNSAddr        AddressProxy;		// For reverse-mapping Sleep Proxy PTR records, address in question
	mDNSs32         TimeRcvd;			// In platform time units
	mDNSs32         TimeExpire;			// In platform time units
	AuthRecType     ARType;             // LocalOnly, P2P or Normal ?

	// Field Group 3: Transient state for Authoritative Records
	mDNSu8          Acknowledged;		// Set if we've given the success callback to the client
	mDNSu8          ProbeCount;			// Number of probes remaining before this record is valid (kDNSRecordTypeUnique)
	mDNSu8          AnnounceCount;		// Number of announcements remaining (kDNSRecordTypeShared)
	mDNSu8          RequireGoodbye;		// Set if this RR has been announced on the wire and will require a goodbye packet
	mDNSu8          AnsweredLocalQ;		// Set if this AuthRecord has been delivered to any local question (LocalOnly or mDNSInterface_Any)
	mDNSu8          IncludeInProbe;		// Set if this RR is being put into a probe right now
	mDNSu8          ImmedUnicast;		// Set if we may send our response directly via unicast to the requester
	mDNSInterfaceID SendNSECNow;		// Set if we need to generate associated NSEC data for this rrname
	mDNSInterfaceID ImmedAnswer;		// Someone on this interface issued a query we need to answer (all-ones for all interfaces)
#if MDNS_LOG_ANSWER_SUPPRESSION_TIMES
	mDNSs32         ImmedAnswerMarkTime;
#endif
	mDNSInterfaceID ImmedAdditional;	// Hint that we might want to also send this record, just to be helpful
	mDNSInterfaceID SendRNow;			// The interface this query is being sent on right now
	mDNSv4Addr      v4Requester;		// Recent v4 query for this record, or all-ones if more than one recent query
	mDNSv6Addr      v6Requester;		// Recent v6 query for this record, or all-ones if more than one recent query
	AuthRecord     *NextResponse;		// Link to the next element in the chain of responses to generate
	const mDNSu8   *NR_AnswerTo;		// Set if this record was selected by virtue of being a direct answer to a question
	AuthRecord     *NR_AdditionalTo;	// Set if this record was selected by virtue of being additional to another
	mDNSs32         ThisAPInterval;		// In platform time units: Current interval for announce/probe
	mDNSs32         LastAPTime;			// In platform time units: Last time we sent announcement/probe
	mDNSs32         LastMCTime;			// Last time we multicast this record (used to guard against packet-storm attacks)
	mDNSInterfaceID LastMCInterface;	// Interface this record was multicast on at the time LastMCTime was recorded
	RData          *NewRData;			// Set if we are updating this record with new rdata
	mDNSu16         newrdlength;		// ... and the length of the new RData
	mDNSRecordUpdateCallback *UpdateCallback;
	mDNSu32         UpdateCredits;		// Token-bucket rate limiting of excessive updates
	mDNSs32         NextUpdateCredit;	// Time next token is added to bucket
	mDNSs32         UpdateBlocked;		// Set if update delaying is in effect

	// Field Group 4: Transient uDNS state for Authoritative Records
	regState_t   state;			// Maybe combine this with resrec.RecordType state? Right now it's ambiguous and confusing.
								// e.g. rr->resrec.RecordType can be kDNSRecordTypeUnregistered,
								// and rr->state can be regState_Unregistered
								// What if we find one of those statements is true and the other false? What does that mean?
	mDNSBool     uselease;		// dynamic update contains (should contain) lease option
	mDNSs32      expire;		// In platform time units: expiration of lease (-1 for static)
	mDNSBool     Private;		// If zone is private, DNS updates may have to be encrypted to prevent eavesdropping
	mDNSOpaque16 updateid;		// Identifier to match update request and response -- also used when transferring records to Sleep Proxy
	const domainname *zone;		// the zone that is updated
	ZoneData  *nta;
	struct tcpInfo_t *tcp;
	NATTraversalInfo  NATinfo;
	mDNSBool SRVChanged;       // temporarily deregistered service because its SRV target or port changed
	mergeState_t  mState;      // Unicast Record Registrations merge state
	mDNSu8		  refreshCount; // Number of refreshes to the server
	mStatus		  updateError;  // Record update resulted in Error ?

	// uDNS_UpdateRecord support fields
	// Do we really need all these in *addition* to NewRData and newrdlength above?
	void *UpdateContext;	// Context parameter for the update callback function
	mDNSu16 OrigRDLen;		// previously registered, being deleted
	mDNSu16 InFlightRDLen;	// currently being registered
	mDNSu16 QueuedRDLen;	// pending operation (re-transmitting if necessary) THEN register the queued update
	RData *OrigRData;
	RData *InFlightRData;
	RData *QueuedRData;

	// Field Group 5: Large data objects go at the end
	domainname      namestorage;
	RData           rdatastorage;		// Normally the storage is right here, except for oversized records
	// rdatastorage MUST be the last thing in the structure -- when using oversized AuthRecords, extra bytes
	// are appended after the end of the AuthRecord, logically augmenting the size of the rdatastorage
	// DO NOT ADD ANY MORE FIELDS HERE
	};

// IsLocalDomain alone is not sufficient to determine that a record is mDNS or uDNS. By default domain names within
// the "local" pseudo-TLD (and within the IPv4 and IPv6 link-local reverse mapping domains) are automatically treated
// as mDNS records, but it is also possible to force any record (even those not within one of the inherently local
// domains) to be handled as an mDNS record by setting the ForceMCast flag, or by setting a non-zero InterfaceID.
// For example, the reverse-mapping PTR record created in AdvertiseInterface sets the ForceMCast flag, since it points to
// a dot-local hostname, and therefore it would make no sense to register this record with a wide-area Unicast DNS server.
// The same applies to Sleep Proxy records, which we will answer for when queried via mDNS, but we never want to try
// to register them with a wide-area Unicast DNS server -- and we probably don't have the required credentials anyway.
// Currently we have no concept of a wide-area uDNS record scoped to a particular interface, so if the InterfaceID is
// nonzero we treat this the same as ForceMCast.
// Note: Question_uDNS(Q) is used in *only* one place -- on entry to mDNS_StartQuery_internal, to decide whether to set TargetQID.
// Everywhere else in the code, the determination of whether a question is unicast is made by checking to see if TargetQID is nonzero.
#define AuthRecord_uDNS(R) ((R)->resrec.InterfaceID == mDNSInterface_Any && !(R)->ForceMCast && !IsLocalDomain((R)->resrec.name))
#define Question_uDNS(Q)   ((Q)->InterfaceID == mDNSInterface_Unicast || \
	((Q)->InterfaceID != mDNSInterface_LocalOnly && (Q)->InterfaceID != mDNSInterface_P2P && !(Q)->ForceMCast && !IsLocalDomain(&(Q)->qname)))

#define RRLocalOnly(rr) ((rr)->ARType == AuthRecordLocalOnly || (rr)->ARType == AuthRecordP2P)

#define RRAny(rr) ((rr)->ARType == AuthRecordAny || (rr)->ARType == AuthRecordAnyIncludeP2P)

// Question (A or AAAA) that is suppressed currently because IPv4 or IPv6 address
// is not available locally for A or AAAA question respectively
#define QuerySuppressed(Q) ((Q)->SuppressUnusable && (Q)->SuppressQuery)

#define PrivateQuery(Q) ((Q)->AuthInfo && (Q)->AuthInfo->AutoTunnel)

// Normally we always lookup the cache and /etc/hosts before sending the query on the wire. For single label
// queries (A and AAAA) that are unqualified (indicated by AppendSearchDomains), we want to append search
// domains before we try them as such
#define ApplySearchDomainsFirst(q) ((q)->AppendSearchDomains && (CountLabels(&((q)->qname))) == 1)

// Wrapper struct for Auth Records for higher-level code that cannot use the AuthRecord's ->next pointer field
typedef struct ARListElem
	{
	struct ARListElem *next;
	AuthRecord ar;          // Note: Must be last element of structure, to accomodate oversized AuthRecords
	} ARListElem;

struct CacheGroup_struct				// Header object for a list of CacheRecords with the same name
	{
	CacheGroup     *next;				// Next CacheGroup object in this hash table bucket
	mDNSu32         namehash;			// Name-based (i.e. case insensitive) hash of name
	CacheRecord    *members;			// List of CacheRecords with this same name
	CacheRecord   **rrcache_tail;		// Tail end of that list
	domainname     *name;				// Common name for all CacheRecords in this list
	// Size to here is 20 bytes when compiling 32-bit; 40 bytes when compiling 64-bit
	mDNSu8          namestorage[InlineCacheGroupNameSize];
	};

struct CacheRecord_struct
	{
	CacheRecord    *next;				// Next in list; first element of structure for efficiency reasons
	ResourceRecord  resrec;				// 36 bytes when compiling for 32-bit; 48 when compiling for 64-bit

	// Transient state for Cache Records
	CacheRecord    *NextInKAList;		// Link to the next element in the chain of known answers to send
	mDNSs32         TimeRcvd;			// In platform time units
	mDNSs32         DelayDelivery;		// Set if we want to defer delivery of this answer to local clients
	mDNSs32         NextRequiredQuery;	// In platform time units
	mDNSs32         LastUsed;			// In platform time units
	DNSQuestion    *CRActiveQuestion;	// Points to an active question referencing this answer. Can never point to a NewQuestion.
	mDNSu32         UnansweredQueries;	// Number of times we've issued a query for this record without getting an answer
	mDNSs32         LastUnansweredTime;	// In platform time units; last time we incremented UnansweredQueries
#if ENABLE_MULTI_PACKET_QUERY_SNOOPING
	mDNSu32         MPUnansweredQ;		// Multi-packet query handling: Number of times we've seen a query for this record
	mDNSs32         MPLastUnansweredQT;	// Multi-packet query handling: Last time we incremented MPUnansweredQ
	mDNSu32         MPUnansweredKA;		// Multi-packet query handling: Number of times we've seen this record in a KA list
	mDNSBool        MPExpectingKA;		// Multi-packet query handling: Set when we increment MPUnansweredQ; allows one KA
#endif
	CacheRecord    *NextInCFList;		// Set if this is in the list of records we just received with the cache flush bit set
	// Size to here is 76 bytes when compiling 32-bit; 104 bytes when compiling 64-bit
	RData_small     smallrdatastorage;	// Storage for small records is right here (4 bytes header + 68 bytes data = 72 bytes)
	};

// Storage sufficient to hold either a CacheGroup header or a CacheRecord
// -- for best efficiency (to avoid wasted unused storage) they should be the same size
typedef union CacheEntity_union CacheEntity;
union CacheEntity_union { CacheEntity *next; CacheGroup cg; CacheRecord cr; };

typedef struct
	{
	CacheRecord r;
	mDNSu8 _extradata[MaximumRDSize-InlineCacheRDSize];		// Glue on the necessary number of extra bytes
	domainname namestorage;									// Needs to go *after* the extra rdata bytes
	} LargeCacheRecord;

typedef struct HostnameInfo
	{
	struct HostnameInfo *next;
	NATTraversalInfo natinfo;
	domainname fqdn;
	AuthRecord arv4;                          // registered IPv4 address record
	AuthRecord arv6;                          // registered IPv6 address record
	mDNSRecordCallback *StatusCallback;       // callback to deliver success or error code to client layer
	const void *StatusContext;                // Client Context
	} HostnameInfo;

typedef struct ExtraResourceRecord_struct ExtraResourceRecord;
struct ExtraResourceRecord_struct
	{
	ExtraResourceRecord *next;
	mDNSu32 ClientID;  // Opaque ID field to be used by client to map an AddRecord call to a set of Extra records
	AuthRecord r;
	// Note: Add any additional fields *before* the AuthRecord in this structure, not at the end.
	// In some cases clients can allocate larger chunks of memory and set r->rdata->MaxRDLength to indicate
	// that this extra memory is available, which would result in any fields after the AuthRecord getting smashed
	};

// Note: Within an mDNSServiceCallback mDNS all API calls are legal except mDNS_Init(), mDNS_Exit(), mDNS_Execute()
typedef void mDNSServiceCallback(mDNS *const m, ServiceRecordSet *const sr, mStatus result);

// A ServiceRecordSet has no special meaning to the core code of the Multicast DNS protocol engine;
// it is just a convenience structure to group together the records that make up a standard service
// registration so that they can be allocted and deallocted together as a single memory object.
// It contains its own ServiceCallback+ServiceContext to report aggregate results up to the next layer of software above.
// It also contains:
//  * the basic PTR/SRV/TXT triplet used to represent any DNS-SD service
//  * the "_services" PTR record for service enumeration
//  * the optional list of SubType PTR records
//  * the optional list of additional records attached to the service set (e.g. iChat pictures)

struct ServiceRecordSet_struct
	{
	// These internal state fields are used internally by mDNSCore; the client layer needn't be concerned with them.
	// No fields need to be set up by the client prior to calling mDNS_RegisterService();
	// all required data is passed as parameters to that function.
	mDNSServiceCallback *ServiceCallback;
	void                *ServiceContext;
	mDNSBool             Conflict;	// Set if this record set was forcibly deregistered because of a conflict

	ExtraResourceRecord *Extras;	// Optional list of extra AuthRecords attached to this service registration
	mDNSu32              NumSubTypes;
	AuthRecord          *SubTypes;
	AuthRecord           RR_ADV;	// e.g. _services._dns-sd._udp.local. PTR _printer._tcp.local.
	AuthRecord           RR_PTR;	// e.g. _printer._tcp.local.        PTR Name._printer._tcp.local.
	AuthRecord           RR_SRV;	// e.g. Name._printer._tcp.local.   SRV 0 0 port target
	AuthRecord           RR_TXT;	// e.g. Name._printer._tcp.local.   TXT PrintQueueName
	// Don't add any fields after AuthRecord RR_TXT.
	// This is where the implicit extra space goes if we allocate a ServiceRecordSet containing an oversized RR_TXT record
	};

// ***************************************************************************
#if 0
#pragma mark -
#pragma mark - Question structures
#endif

// We record the last eight instances of each duplicate query
// This gives us v4/v6 on each of Ethernet, AirPort and Firewire, and two free slots "for future expansion"
// If the host has more active interfaces that this it is not fatal -- duplicate question suppression will degrade gracefully.
// Since we will still remember the last eight, the busiest interfaces will still get the effective duplicate question suppression.
#define DupSuppressInfoSize 8

typedef struct
	{
	mDNSs32               Time;
	mDNSInterfaceID       InterfaceID;
	mDNSs32               Type;				// v4 or v6?
	} DupSuppressInfo;

typedef enum
	{
	LLQ_InitialRequest    = 1,
	LLQ_SecondaryRequest  = 2,
	LLQ_Established       = 3,
	LLQ_Poll              = 4
	} LLQ_State;

// LLQ constants
#define kLLQ_Vers      1
#define kLLQ_DefLease  7200 // 2 hours
#define kLLQ_MAX_TRIES 3    // retry an operation 3 times max
#define kLLQ_INIT_RESEND 2 // resend an un-ack'd packet after 2 seconds, then double for each additional
// LLQ Operation Codes
#define kLLQOp_Setup     1
#define kLLQOp_Refresh   2
#define kLLQOp_Event     3

// LLQ Errror Codes
enum
	{
	LLQErr_NoError    = 0,
	LLQErr_ServFull   = 1,
	LLQErr_Static     = 2,
	LLQErr_FormErr    = 3,
	LLQErr_NoSuchLLQ  = 4,
	LLQErr_BadVers    = 5,
	LLQErr_UnknownErr = 6
	};

enum { NoAnswer_Normal = 0, NoAnswer_Suspended = 1, NoAnswer_Fail = 2 };

#define HMAC_LEN    64
#define HMAC_IPAD   0x36
#define HMAC_OPAD   0x5c
#define MD5_LEN     16

#define AutoTunnelUnregistered(X) (                                              \
	(X)->AutoTunnelHostRecord.resrec.RecordType == kDNSRecordTypeUnregistered && \
	(X)->AutoTunnelDeviceInfo.resrec.RecordType == kDNSRecordTypeUnregistered && \
	(X)->AutoTunnelService.   resrec.RecordType == kDNSRecordTypeUnregistered && \
	(X)->AutoTunnel6Record.   resrec.RecordType == kDNSRecordTypeUnregistered    )

// Internal data structure to maintain authentication information
typedef struct DomainAuthInfo
	{
	struct DomainAuthInfo *next;
	mDNSs32          deltime;				// If we're planning to delete this DomainAuthInfo, the time we want it deleted
	const char*      AutoTunnel;            // If NULL, this is not an AutoTunnel DAI. Otherwise, this is prepended to the IPSec identifier
	AuthRecord       AutoTunnelHostRecord;	// User-visible hostname; used as SRV target for AutoTunnel services
	AuthRecord       AutoTunnelTarget;		// Opaque hostname of tunnel endpoint; used as SRV target for AutoTunnelService record
	AuthRecord       AutoTunnelDeviceInfo;	// Device info of tunnel endpoint
	AuthRecord       AutoTunnelService;		// Service record (possibly NAT-Mapped) of IKE daemon implementing tunnel endpoint
	AuthRecord       AutoTunnel6Record;     // AutoTunnel AAAA Record obtained from Connectivityd
	NATTraversalInfo AutoTunnelNAT;
	domainname       domain;
	domainname       keyname;
	domainname       hostname;
	mDNSIPPort       port;
	char             b64keydata[32];
	mDNSu8           keydata_ipad[HMAC_LEN];	// padded key for inner hash rounds
	mDNSu8           keydata_opad[HMAC_LEN];	// padded key for outer hash rounds
	} DomainAuthInfo;

// Note: Within an mDNSQuestionCallback mDNS all API calls are legal except mDNS_Init(), mDNS_Exit(), mDNS_Execute()
typedef enum { QC_rmv = 0, QC_add = 1, QC_addnocache = 2 } QC_result;
typedef void mDNSQuestionCallback(mDNS *const m, DNSQuestion *question, const ResourceRecord *const answer, QC_result AddRecord);

#define NextQSendTime(Q)  ((Q)->LastQTime + (Q)->ThisQInterval)
#define ActiveQuestion(Q) ((Q)->ThisQInterval > 0 && !(Q)->DuplicateOf)
#define TimeToSendThisQuestion(Q,time) (ActiveQuestion(Q) && (time) - NextQSendTime(Q) >= 0)

struct DNSQuestion_struct
	{
	// Internal state fields. These are used internally by mDNSCore; the client layer needn't be concerned with them.
	DNSQuestion          *next;
	mDNSu32               qnamehash;
	mDNSs32               DelayAnswering;	// Set if we want to defer answering this question until the cache settles
	mDNSs32               LastQTime;		// Last scheduled transmission of this Q on *all* applicable interfaces
	mDNSs32               ThisQInterval;	// LastQTime + ThisQInterval is the next scheduled transmission of this Q
											// ThisQInterval > 0 for an active question;
											// ThisQInterval = 0 for a suspended question that's still in the list
											// ThisQInterval = -1 for a cancelled question (should not still be in list)
	mDNSs32               ExpectUnicastResp;// Set when we send a query with the kDNSQClass_UnicastResponse bit set
	mDNSs32               LastAnswerPktNum;	// The sequence number of the last response packet containing an answer to this Q
	mDNSu32               RecentAnswerPkts;	// Number of answers since the last time we sent this query
	mDNSu32               CurrentAnswers;	// Number of records currently in the cache that answer this question
	mDNSu32               LargeAnswers;		// Number of answers with rdata > 1024 bytes
	mDNSu32               UniqueAnswers;	// Number of answers received with kDNSClass_UniqueRRSet bit set
	mDNSInterfaceID       FlappingInterface1;// Set when an interface goes away, to flag if remove events are delivered for this Q
	mDNSInterfaceID       FlappingInterface2;// Set when an interface goes away, to flag if remove events are delivered for this Q
	DomainAuthInfo       *AuthInfo;			// Non-NULL if query is currently being done using Private DNS
	DNSQuestion          *DuplicateOf;
	DNSQuestion          *NextInDQList;
	DupSuppressInfo       DupSuppress[DupSuppressInfoSize];
	mDNSInterfaceID       SendQNow;			// The interface this query is being sent on right now
	mDNSBool              SendOnAll;		// Set if we're sending this question on all active interfaces
	mDNSu32               RequestUnicast;	// Non-zero if we want to send query with kDNSQClass_UnicastResponse bit set
	mDNSs32               LastQTxTime;		// Last time this Q was sent on one (but not necessarily all) interfaces
	mDNSu32               CNAMEReferrals;	// Count of how many CNAME redirections we've done
	mDNSBool              SuppressQuery;    // This query should be suppressed and not sent on the wire
	mDNSu8                LOAddressAnswers; // Number of answers from the local only auth records that are
		                                    // answering A, AAAA and CNAME (/etc/hosts)
	mDNSu8                WakeOnResolveCount; // Number of wakes that should be sent on resolve
	mDNSs32               StopTime;			// Time this question should be stopped by giving them a negative answer

	// Wide Area fields. These are used internally by the uDNS core
	UDPSocket            *LocalSocket;
	mDNSBool             deliverAddEvents;  // Change in DNSSserver requiring to deliver ADD events
	DNSServer            *qDNSServer;		// Caching server for this query (in the absence of an SRV saying otherwise)
	mDNSOpaque64          validDNSServers;  // Valid DNSServers for this question
	mDNSu16              noServerResponse;  // At least one server did not respond.
	mDNSu16              triedAllServersOnce; // Tried all DNS servers once
	mDNSu8               unansweredQueries;// The number of unanswered queries to this server

	ZoneData             *nta;				// Used for getting zone data for private or LLQ query
	mDNSAddr              servAddr;			// Address and port learned from _dns-llq, _dns-llq-tls or _dns-query-tls SRV query
	mDNSIPPort            servPort;
	struct tcpInfo_t *tcp;
	mDNSIPPort            tcpSrcPort;		// Local Port TCP packet received on;need this as tcp struct is disposed
											// by tcpCallback before calling into mDNSCoreReceive
	mDNSu8                NoAnswer;			// Set if we want to suppress answers until tunnel setup has completed

	// LLQ-specific fields. These fields are only meaningful when LongLived flag is set
	LLQ_State             state;
	mDNSu32               ReqLease;			// seconds (relative)
	mDNSs32               expire;			// ticks (absolute)
	mDNSs16               ntries;           // for UDP: the number of packets sent for this LLQ state
	                                       // for TCP: there is some ambiguity in the use of this variable, but in general, it is
	                                       //          the number of TCP/TLS connection attempts for this LLQ state, or
	                                       //          the number of packets sent for this TCP/TLS connection
	mDNSOpaque64          id;

	// Client API fields: The client must set up these fields *before* calling mDNS_StartQuery()
	mDNSInterfaceID       InterfaceID;		// Non-zero if you want to issue queries only on a single specific IP interface
	mDNSAddr              Target;			// Non-zero if you want to direct queries to a specific unicast target address
	mDNSIPPort            TargetPort;		// Must be set if Target is set
	mDNSOpaque16          TargetQID;		// Must be set if Target is set
	domainname            qname;
	mDNSu16               qtype;
	mDNSu16               qclass;
	mDNSBool              LongLived;        // Set by client for calls to mDNS_StartQuery to indicate LLQs to unicast layer.
	mDNSBool              ExpectUnique;		// Set by client if it's expecting unique RR(s) for this question, not shared RRs
	mDNSBool              ForceMCast;		// Set by client to force mDNS query, even for apparently uDNS names
	mDNSBool              ReturnIntermed;	// Set by client to request callbacks for intermediate CNAME/NXDOMAIN results
	mDNSBool              SuppressUnusable; // Set by client to suppress unusable queries to be sent on the wire
	mDNSBool              RetryWithSearchDomains;	// Retry with search domains if there is no entry in the cache or AuthRecords
	mDNSu8                TimeoutQuestion; // Timeout this question if there is no reply in configured time
	mDNSu8                WakeOnResolve; // Send wakeup on resolve
	mDNSs8                SearchListIndex;  // Index into SearchList; Used by the client layer but not touched by core
	mDNSs8                AppendSearchDomains; // Search domains can be appended for this query
	mDNSs8                AppendLocalSearchDomains; // Search domains ending in .local can be appended for this query
	domainname           *qnameOrig;       // Copy of the original question name if it is not fully qualified
	mDNSQuestionCallback *QuestionCallback;
	void                 *QuestionContext;
	};

typedef struct
	{
	// Client API fields: The client must set up name and InterfaceID *before* calling mDNS_StartResolveService()
	// When the callback is invoked, ip, port, TXTlen and TXTinfo will have been filled in with the results learned from the network.
	domainname      name;
	mDNSInterfaceID InterfaceID;		// ID of the interface the response was received on
	mDNSAddr        ip;					// Remote (destination) IP address where this service can be accessed
	mDNSIPPort      port;				// Port where this service can be accessed
	mDNSu16         TXTlen;
	mDNSu8          TXTinfo[2048];		// Additional demultiplexing information (e.g. LPR queue name)
	} ServiceInfo;

// Note: Within an mDNSServiceInfoQueryCallback mDNS all API calls are legal except mDNS_Init(), mDNS_Exit(), mDNS_Execute()
typedef struct ServiceInfoQuery_struct ServiceInfoQuery;
typedef void mDNSServiceInfoQueryCallback(mDNS *const m, ServiceInfoQuery *query);
struct ServiceInfoQuery_struct
	{
	// Internal state fields. These are used internally by mDNSCore; the client layer needn't be concerned with them.
	// No fields need to be set up by the client prior to calling mDNS_StartResolveService();
	// all required data is passed as parameters to that function.
	// The ServiceInfoQuery structure memory is working storage for mDNSCore to discover the requested information
	// and place it in the ServiceInfo structure. After the client has called mDNS_StopResolveService(), it may
	// dispose of the ServiceInfoQuery structure while retaining the results in the ServiceInfo structure.
	DNSQuestion                   qSRV;
	DNSQuestion                   qTXT;
	DNSQuestion                   qAv4;
	DNSQuestion                   qAv6;
	mDNSu8                        GotSRV;
	mDNSu8                        GotTXT;
	mDNSu8                        GotADD;
	mDNSu32                       Answers;
	ServiceInfo                  *info;
	mDNSServiceInfoQueryCallback *ServiceInfoQueryCallback;
	void                         *ServiceInfoQueryContext;
	};

typedef enum { ZoneServiceUpdate, ZoneServiceQuery, ZoneServiceLLQ } ZoneService;

typedef void ZoneDataCallback(mDNS *const m, mStatus err, const ZoneData *result);

struct ZoneData_struct
	{
	domainname       ChildName;			// Name for which we're trying to find the responsible server
	ZoneService      ZoneService;		// Which service we're seeking for this zone (update, query, or LLQ)
	domainname       *CurrentSOA;		// Points to somewhere within ChildName
	domainname       ZoneName;			// Discovered result: Left-hand-side of SOA record
	mDNSu16          ZoneClass;			// Discovered result: DNS Class from SOA record
	domainname       Host;				// Discovered result: Target host from SRV record
	mDNSIPPort       Port;				// Discovered result: Update port, query port, or LLQ port from SRV record
	mDNSAddr         Addr;				// Discovered result: Address of Target host from SRV record
	mDNSBool         ZonePrivate;		// Discovered result: Does zone require encrypted queries?
	ZoneDataCallback *ZoneDataCallback;	// Caller-specified function to be called upon completion
	void             *ZoneDataContext;
	DNSQuestion      question;			// Storage for any active question
	};

extern ZoneData *StartGetZoneData(mDNS *const m, const domainname *const name, const ZoneService target, ZoneDataCallback callback, void *callbackInfo);
extern void CancelGetZoneData(mDNS *const m, ZoneData *nta);
extern mDNSBool IsGetZoneDataQuestion(DNSQuestion *q);

typedef struct DNameListElem
	{
	struct DNameListElem *next;
	mDNSu32 uid;
	domainname name;
	} DNameListElem;

#if APPLE_OSX_mDNSResponder
// Different states that we go through locating the peer
#define TC_STATE_AAAA_PEER			0x000000001		/* Peer's BTMM IPv6 address */
#define TC_STATE_AAAA_PEER_RELAY	0x000000002		/* Peer's IPv6 Relay address */
#define TC_STATE_SRV_PEER			0x000000003		/* Peer's SRV Record corresponding to IPv4 address */
#define TC_STATE_ADDR_PEER			0x000000004		/* Peer's IPv4 address */

typedef struct ClientTunnel
	{
	struct ClientTunnel *next;
	const char *prefix;
	domainname dstname;
	mDNSBool   MarkedForDeletion;
	mDNSv6Addr loc_inner;
	mDNSv4Addr loc_outer;
	mDNSv6Addr loc_outer6;
	mDNSv6Addr rmt_inner;
	mDNSv4Addr rmt_outer;
	mDNSv6Addr rmt_outer6;
	mDNSIPPort rmt_outer_port;
	mDNSu16	tc_state;
	DNSQuestion q;
	} ClientTunnel;
#endif

// ***************************************************************************
#if 0
#pragma mark -
#pragma mark - NetworkInterfaceInfo_struct
#endif

typedef struct NetworkInterfaceInfo_struct NetworkInterfaceInfo;

// A NetworkInterfaceInfo_struct serves two purposes:
// 1. It holds the address, PTR and HINFO records to advertise a given IP address on a given physical interface
// 2. It tells mDNSCore which physical interfaces are available; each physical interface has its own unique InterfaceID.
//    Since there may be multiple IP addresses on a single physical interface,
//    there may be multiple NetworkInterfaceInfo_structs with the same InterfaceID.
//    In this case, to avoid sending the same packet n times, when there's more than one
//    struct with the same InterfaceID, mDNSCore picks one member of the set to be the
//    active representative of the set; all others have the 'InterfaceActive' flag unset.

struct NetworkInterfaceInfo_struct
	{
	// Internal state fields. These are used internally by mDNSCore; the client layer needn't be concerned with them.
	NetworkInterfaceInfo *next;

	mDNSu8          InterfaceActive;	// Set if interface is sending & receiving packets (see comment above)
	mDNSu8          IPv4Available;		// If InterfaceActive, set if v4 available on this InterfaceID
	mDNSu8          IPv6Available;		// If InterfaceActive, set if v6 available on this InterfaceID

	DNSQuestion     NetWakeBrowse;
	DNSQuestion     NetWakeResolve[3];	// For fault-tolerance, we try up to three Sleep Proxies
	mDNSAddr        SPSAddr[3];
	mDNSIPPort      SPSPort[3];
	mDNSs32         NextSPSAttempt;		// -1 if we're not currently attempting to register with any Sleep Proxy
	mDNSs32         NextSPSAttemptTime;

	// Standard AuthRecords that every Responder host should have (one per active IP address)
	AuthRecord RR_A;					// 'A' or 'AAAA' (address) record for our ".local" name
	AuthRecord RR_PTR;					// PTR (reverse lookup) record
	AuthRecord RR_HINFO;

	// Client API fields: The client must set up these fields *before* calling mDNS_RegisterInterface()
	mDNSInterfaceID InterfaceID;		// Identifies physical interface; MUST NOT be 0, -1, or -2
	mDNSAddr        ip;					// The IPv4 or IPv6 address to advertise
	mDNSAddr        mask;
	mDNSEthAddr     MAC;
	char            ifname[64];			// Windows uses a GUID string for the interface name, which doesn't fit in 16 bytes
	mDNSu8          Advertise;			// False if you are only searching on this interface
	mDNSu8          McastTxRx;			// Send/Receive multicast on this { InterfaceID, address family } ?
	mDNSu8          NetWake;			// Set if Wake-On-Magic-Packet is enabled on this interface
	mDNSu8          Loopback;			// Set if this is the loopback interface
	};

#define SLE_DELETE              0x00000001
#define SLE_WAB_QUERY_STARTED   0x00000002

typedef struct SearchListElem
	{
	struct SearchListElem *next;
	domainname domain;
	int flag;
	mDNSInterfaceID InterfaceID;
	DNSQuestion BrowseQ;
	DNSQuestion DefBrowseQ;
	DNSQuestion AutomaticBrowseQ;
	DNSQuestion RegisterQ;
	DNSQuestion DefRegisterQ;
	int	numCfAnswers;
	ARListElem *AuthRecs;
	} SearchListElem;

// For domain enumeration and automatic browsing
// This is the user's DNS search list.
// In each of these domains we search for our special pointer records (lb._dns-sd._udp.<domain>, etc.)
// to discover recommended domains for domain enumeration (browse, default browse, registration,
// default registration) and possibly one or more recommended automatic browsing domains.
extern SearchListElem *SearchList;		// This really ought to be part of mDNS_struct -- SC

// ***************************************************************************
#if 0
#pragma mark -
#pragma mark - Main mDNS object, used to hold all the mDNS state
#endif

typedef void mDNSCallback(mDNS *const m, mStatus result);

#define CACHE_HASH_SLOTS 499

enum		// Bit flags -- i.e. values should be 1, 2, 4, 8, etc.
	{
	mDNS_KnownBug_LimitedIPv6       = 1,
	mDNS_KnownBug_LossySyslog       = 2		// <rdar://problem/6561888>
	};

enum
	{
	SleepState_Awake = 0,
	SleepState_Transferring = 1,
	SleepState_Sleeping = 2
	};

struct mDNS_struct
	{
	// Internal state fields. These hold the main internal state of mDNSCore;
	// the client layer needn't be concerned with them.
	// No fields need to be set up by the client prior to calling mDNS_Init();
	// all required data is passed as parameters to that function.

	mDNS_PlatformSupport *p;			// Pointer to platform-specific data of indeterminite size
	mDNSu32  KnownBugs;
	mDNSBool CanReceiveUnicastOn5353;
	mDNSBool AdvertiseLocalAddresses;
	mDNSBool DivertMulticastAdvertisements; // from interfaces that do not advertise local addresses to local-only
	mStatus mDNSPlatformStatus;
	mDNSIPPort UnicastPort4;
	mDNSIPPort UnicastPort6;
	mDNSEthAddr PrimaryMAC;				// Used as unique host ID
	mDNSCallback *MainCallback;
	void         *MainContext;

	// For debugging: To catch and report locking failures
	mDNSu32 mDNS_busy;					// Incremented between mDNS_Lock/mDNS_Unlock section
	mDNSu32 mDNS_reentrancy;			// Incremented when calling a client callback
	mDNSu8  lock_rrcache;				// For debugging: Set at times when these lists may not be modified
	mDNSu8  lock_Questions;
	mDNSu8  lock_Records;
#ifndef MaxMsg
	#define MaxMsg 160
#endif
	char MsgBuffer[MaxMsg];				// Temp storage used while building error log messages

	// Task Scheduling variables
	mDNSs32  timenow_adjust;			// Correction applied if we ever discover time went backwards
	mDNSs32  timenow;					// The time that this particular activation of the mDNS code started
	mDNSs32  timenow_last;				// The time the last time we ran
	mDNSs32  NextScheduledEvent;		// Derived from values below
	mDNSs32  ShutdownTime;				// Set when we're shutting down; allows us to skip some unnecessary steps
	mDNSs32  SuppressSending;			// Don't send local-link mDNS packets during this time
	mDNSs32  NextCacheCheck;			// Next time to refresh cache record before it expires
	mDNSs32  NextScheduledQuery;		// Next time to send query in its exponential backoff sequence
	mDNSs32  NextScheduledProbe;		// Next time to probe for new authoritative record
	mDNSs32  NextScheduledResponse;		// Next time to send authoritative record(s) in responses
	mDNSs32  NextScheduledNATOp;		// Next time to send NAT-traversal packets
	mDNSs32  NextScheduledSPS;			// Next time to purge expiring Sleep Proxy records
	mDNSs32  RandomQueryDelay;			// For de-synchronization of query packets on the wire
	mDNSu32  RandomReconfirmDelay;		// For de-synchronization of reconfirmation queries on the wire
	mDNSs32  PktNum;					// Unique sequence number assigned to each received packet
	mDNSu8   LocalRemoveEvents;			// Set if we may need to deliver remove events for local-only questions and/or local-only records
	mDNSu8   SleepState;				// Set if we're sleeping
	mDNSu8   SleepSeqNum;				// "Epoch number" of our current period of wakefulness
	mDNSu8   SystemWakeOnLANEnabled;	// Set if we want to register with a Sleep Proxy before going to sleep
	mDNSu8   SentSleepProxyRegistration;// Set if we registered (or tried to register) with a Sleep Proxy
	mDNSu8   SystemSleepOnlyIfWakeOnLAN;// Set if we may only sleep if we managed to register with a Sleep Proxy
	mDNSs32  AnnounceOwner;				// After waking from sleep, include OWNER option in packets until this time
	mDNSs32  DelaySleep;				// To inhibit re-sleeping too quickly right after wake
	mDNSs32  SleepLimit;				// Time window to allow deregistrations, etc.,
										// during which underying platform layer should inhibit system sleep
	mDNSs32  NextScheduledSPRetry;		// Time next sleep proxy registration action is required.
										// Only valid if SleepLimit is nonzero and DelaySleep is zero.

	mDNSs32 NextScheduledStopTime;      // Next time to stop a question

	// These fields only required for mDNS Searcher...
	DNSQuestion *Questions;				// List of all registered questions, active and inactive
	DNSQuestion *NewQuestions;			// Fresh questions not yet answered from cache
	DNSQuestion *CurrentQuestion;		// Next question about to be examined in AnswerLocalQuestions()
	DNSQuestion *LocalOnlyQuestions;	// Questions with InterfaceID set to mDNSInterface_LocalOnly or mDNSInterface_P2P
	DNSQuestion *NewLocalOnlyQuestions;	// Fresh local-only or P2P questions not yet answered
	DNSQuestion *RestartQuestion;		// Questions that are being restarted (stop followed by start)
	mDNSu32 rrcache_size;				// Total number of available cache entries
	mDNSu32 rrcache_totalused;			// Number of cache entries currently occupied
	mDNSu32 rrcache_active;				// Number of cache entries currently occupied by records that answer active questions
	mDNSu32 rrcache_report;
	CacheEntity *rrcache_free;
	CacheGroup *rrcache_hash[CACHE_HASH_SLOTS];
	mDNSs32  rrcache_nextcheck[CACHE_HASH_SLOTS];

	AuthHash rrauth;

	// Fields below only required for mDNS Responder...
	domainlabel nicelabel;				// Rich text label encoded using canonically precomposed UTF-8
	domainlabel hostlabel;				// Conforms to RFC 1034 "letter-digit-hyphen" ARPANET host name rules
	domainname  MulticastHostname;		// Fully Qualified "dot-local" Host Name, e.g. "Foo.local."
	UTF8str255  HIHardware;
	UTF8str255  HISoftware;
	AuthRecord  DeviceInfo;
	AuthRecord *ResourceRecords;
	AuthRecord *DuplicateRecords;		// Records currently 'on hold' because they are duplicates of existing records
	AuthRecord *NewLocalRecords;		// Fresh AuthRecords (public) not yet delivered to our local-only questions
	AuthRecord *CurrentRecord;			// Next AuthRecord about to be examined
	mDNSBool    NewLocalOnlyRecords;	// Fresh AuthRecords (local only) not yet delivered to our local questions
	NetworkInterfaceInfo *HostInterfaces;
	mDNSs32 ProbeFailTime;
	mDNSu32 NumFailedProbes;
	mDNSs32 SuppressProbes;

	// Unicast-specific data
	mDNSs32           NextuDNSEvent;		// uDNS next event
	mDNSs32           NextSRVUpdate;        // Time to perform delayed update

	DNSServer        *DNSServers;           // list of DNS servers
	McastResolver    *McastResolvers;       // list of Mcast Resolvers

	mDNSAddr          Router;
	mDNSAddr          AdvertisedV4;         // IPv4 address pointed to by hostname
	mDNSAddr          AdvertisedV6;         // IPv6 address pointed to by hostname

	DomainAuthInfo   *AuthInfoList;         // list of domains requiring authentication for updates

	DNSQuestion       ReverseMap;           // Reverse-map query to find static hostname for service target
	DNSQuestion       AutomaticBrowseDomainQ;
	domainname        StaticHostname;       // Current answer to reverse-map query
	domainname        FQDN;
	HostnameInfo     *Hostnames;            // List of registered hostnames + hostname metadata
	mDNSv6Addr        AutoTunnelHostAddr;	// IPv6 address advertised for AutoTunnel services on this machine
	mDNSBool          AutoTunnelHostAddrActive;
	// AutoTunnel Relay address has two distinct uses
	// AutoTunnelRelayAddrIn: If non-zero, it means that this host can be reached (inbound connection) through the relay
	// AutoTunnelRelayAddrOut: If non-zero, it means that this host can use the relay to reach (outbound connection) the
	// other hosts through the relay
	mDNSv6Addr        AutoTunnelRelayAddrIn;
	mDNSv6Addr        AutoTunnelRelayAddrOut;
	domainlabel       AutoTunnelLabel;		// Used to construct hostname for *IPv4* address of tunnel endpoints

	mDNSBool          StartWABQueries;		// Start WAB queries for the purpose of domain enumeration
	mDNSBool          RegisterAutoTunnel6;

	// NAT-Traversal fields
	NATTraversalInfo  LLQNAT;					// Single shared NAT Traversal to receive inbound LLQ notifications
	NATTraversalInfo *NATTraversals;
	NATTraversalInfo *CurrentNATTraversal;
	mDNSs32           retryIntervalGetAddr;		// delta between time sent and retry
	mDNSs32           retryGetAddr;				// absolute time when we retry
	mDNSv4Addr        ExternalAddress;

	UDPSocket        *NATMcastRecvskt;			// For receiving NAT-PMP AddrReply multicasts from router on port 5350
	mDNSu32           LastNATupseconds;			// NAT engine uptime in seconds, from most recent NAT packet
	mDNSs32           LastNATReplyLocalTime;	// Local time in ticks when most recent NAT packet was received
	mDNSu16           LastNATMapResultCode;		// Most recent error code for mappings

	tcpLNTInfo        tcpAddrInfo;				// legacy NAT traversal TCP connection info for external address
	tcpLNTInfo        tcpDeviceInfo;			// legacy NAT traversal TCP connection info for device info
	tcpLNTInfo       *tcpInfoUnmapList;			// list of pending unmap requests
	mDNSInterfaceID   UPnPInterfaceID;
	UDPSocket        *SSDPSocket;               // For SSDP request/response
	mDNSBool          SSDPWANPPPConnection;     // whether we should send the SSDP query for WANIPConnection or WANPPPConnection
	mDNSIPPort        UPnPRouterPort;			// port we send discovery messages to
	mDNSIPPort        UPnPSOAPPort;				// port we send SOAP messages to
	mDNSu8           *UPnPRouterURL;			// router's URL string
	mDNSBool          UPnPWANPPPConnection;     // whether we're using WANIPConnection or WANPPPConnection
	mDNSu8           *UPnPSOAPURL;				// router's SOAP control URL string
	mDNSu8           *UPnPRouterAddressString;	// holds both the router's address and port
	mDNSu8           *UPnPSOAPAddressString;	// holds both address and port for SOAP messages

	// Sleep Proxy Server fields
	mDNSu8            SPSType;					// 0 = off, 10-99 encodes desirability metric
	mDNSu8            SPSPortability;			// 10-99
	mDNSu8            SPSMarginalPower;			// 10-99
	mDNSu8            SPSTotalPower;			// 10-99
	mDNSu8            SPSState;					// 0 = off, 1 = running, 2 = shutting down, 3 = suspended during sleep
	mDNSInterfaceID   SPSProxyListChanged;
	UDPSocket        *SPSSocket;
	ServiceRecordSet  SPSRecords;
	mDNSQuestionCallback *SPSBrowseCallback;    // So the platform layer can do something useful with SPS browse results
	int               ProxyRecords;				// Total number of records we're holding as proxy
	#define           MAX_PROXY_RECORDS 10000	/* DOS protection: 400 machines at 25 records each */

#if APPLE_OSX_mDNSResponder
	ClientTunnel     *TunnelClients;
	uuid_t           asl_uuid;					// uuid for ASL logging
	void		    *WCF;
#endif

	// Fixed storage, to avoid creating large objects on the stack
	// The imsg is declared as a union with a pointer type to enforce CPU-appropriate alignment
	union { DNSMessage m; void *p; } imsg;  // Incoming message received from wire
	DNSMessage        omsg;                 // Outgoing message we're building
	LargeCacheRecord  rec;                  // Resource Record extracted from received message
	};

#define FORALL_CACHERECORDS(SLOT,CG,CR)                           \
	for ((SLOT) = 0; (SLOT) < CACHE_HASH_SLOTS; (SLOT)++)         \
		for ((CG)=m->rrcache_hash[(SLOT)]; (CG); (CG)=(CG)->next) \
			for ((CR) = (CG)->members; (CR); (CR)=(CR)->next)

// ***************************************************************************
#if 0
#pragma mark -
#pragma mark - Useful Static Constants
#endif

extern const mDNSInterfaceID mDNSInterface_Any;				// Zero
extern const mDNSInterfaceID mDNSInterface_LocalOnly;		// Special value
extern const mDNSInterfaceID mDNSInterface_Unicast;			// Special value
extern const mDNSInterfaceID mDNSInterfaceMark;				// Special value
extern const mDNSInterfaceID mDNSInterface_P2P;				// Special value

extern const mDNSIPPort   DiscardPort;
extern const mDNSIPPort   SSHPort;
extern const mDNSIPPort   UnicastDNSPort;
extern const mDNSIPPort   SSDPPort;
extern const mDNSIPPort   IPSECPort;
extern const mDNSIPPort   NSIPCPort;
extern const mDNSIPPort   NATPMPAnnouncementPort;
extern const mDNSIPPort   NATPMPPort;
extern const mDNSIPPort   DNSEXTPort;
extern const mDNSIPPort   MulticastDNSPort;
extern const mDNSIPPort   LoopbackIPCPort;
extern const mDNSIPPort   PrivateDNSPort;

extern const OwnerOptData    zeroOwner;

extern const mDNSIPPort      zeroIPPort;
extern const mDNSv4Addr      zerov4Addr;
extern const mDNSv6Addr      zerov6Addr;
extern const mDNSEthAddr     zeroEthAddr;
extern const mDNSv4Addr      onesIPv4Addr;
extern const mDNSv6Addr      onesIPv6Addr;
extern const mDNSEthAddr     onesEthAddr;
extern const mDNSAddr        zeroAddr;

extern const mDNSv4Addr   AllDNSAdminGroup;
extern const mDNSv4Addr   AllHosts_v4;
extern const mDNSv6Addr   AllHosts_v6;
extern const mDNSv6Addr   NDP_prefix;
extern const mDNSEthAddr  AllHosts_v6_Eth;
extern const mDNSAddr     AllDNSLinkGroup_v4;
extern const mDNSAddr     AllDNSLinkGroup_v6;

extern const mDNSOpaque16 zeroID;
extern const mDNSOpaque16 onesID;
extern const mDNSOpaque16 QueryFlags;
extern const mDNSOpaque16 uQueryFlags;
extern const mDNSOpaque16 ResponseFlags;
extern const mDNSOpaque16 UpdateReqFlags;
extern const mDNSOpaque16 UpdateRespFlags;

extern const mDNSOpaque64 zeroOpaque64;

extern mDNSBool StrictUnicastOrdering;
extern mDNSu8 NumUnicastDNSServers;

#define localdomain           (*(const domainname *)"\x5" "local")
#define DeviceInfoName        (*(const domainname *)"\xC" "_device-info" "\x4" "_tcp")
#define SleepProxyServiceType (*(const domainname *)"\xC" "_sleep-proxy" "\x4" "_udp")

// ***************************************************************************
#if 0
#pragma mark -
#pragma mark - Inline functions
#endif

#if (defined(_MSC_VER))
	#define mDNSinline static __inline
#elif ((__GNUC__ > 2) || ((__GNUC__ == 2) && (__GNUC_MINOR__ >= 9)))
	#define mDNSinline static inline
#endif

// If we're not doing inline functions, then this header needs to have the extern declarations
#if !defined(mDNSinline)
extern mDNSs32      NonZeroTime(mDNSs32 t);
extern mDNSu16      mDNSVal16(mDNSOpaque16 x);
extern mDNSOpaque16 mDNSOpaque16fromIntVal(mDNSu16 v);
#endif

// If we're compiling the particular C file that instantiates our inlines, then we
// define "mDNSinline" (to empty string) so that we generate code in the following section
#if (!defined(mDNSinline) && mDNS_InstantiateInlines)
#define mDNSinline
#endif

#ifdef mDNSinline

mDNSinline mDNSs32 NonZeroTime(mDNSs32 t) { if (t) return(t); else return(1); }

mDNSinline mDNSu16 mDNSVal16(mDNSOpaque16 x) { return((mDNSu16)((mDNSu16)x.b[0] <<  8 | (mDNSu16)x.b[1])); }

mDNSinline mDNSOpaque16 mDNSOpaque16fromIntVal(mDNSu16 v)
	{
	mDNSOpaque16 x;
	x.b[0] = (mDNSu8)(v >> 8);
	x.b[1] = (mDNSu8)(v & 0xFF);
	return(x);
	}

#endif

// ***************************************************************************
#if 0
#pragma mark -
#pragma mark - Main Client Functions
#endif

// Every client should call mDNS_Init, passing in storage for the mDNS object and the mDNS_PlatformSupport object.
//
// Clients that are only advertising services should use mDNS_Init_NoCache and mDNS_Init_ZeroCacheSize.
// Clients that plan to perform queries (mDNS_StartQuery, mDNS_StartBrowse, mDNS_StartResolveService, etc.)
// need to provide storage for the resource record cache, or the query calls will return 'mStatus_NoCache'.
// The rrcachestorage parameter is the address of memory for the resource record cache, and
// the rrcachesize parameter is the number of entries in the CacheRecord array passed in.
// (i.e. the size of the cache memory needs to be sizeof(CacheRecord) * rrcachesize).
// OS X 10.3 Panther uses an initial cache size of 64 entries, and then mDNSCore sends an
// mStatus_GrowCache message if it needs more.
//
// Most clients should use mDNS_Init_AdvertiseLocalAddresses. This causes mDNSCore to automatically
// create the correct address records for all the hosts interfaces. If you plan to advertise
// services being offered by the local machine, this is almost always what you want.
// There are two cases where you might use mDNS_Init_DontAdvertiseLocalAddresses:
// 1. A client-only device, that browses for services but doesn't advertise any of its own.
// 2. A proxy-registration service, that advertises services being offered by other machines, and takes
//    the appropriate steps to manually create the correct address records for those other machines.
// In principle, a proxy-like registration service could manually create address records for its own machine too,
// but this would be pointless extra effort when using mDNS_Init_AdvertiseLocalAddresses does that for you.
//
// Note that a client-only device that wishes to prohibit multicast advertisements (e.g. from
// higher-layer API calls) must also set DivertMulticastAdvertisements in the mDNS structure and
// advertise local address(es) on a loopback interface.
//
// When mDNS has finished setting up the client's callback is called
// A client can also spin and poll the mDNSPlatformStatus field to see when it changes from mStatus_Waiting to mStatus_NoError
//
// Call mDNS_StartExit to tidy up before exiting
// Because exiting may be an asynchronous process (e.g. if unicast records need to be deregistered)
// client layer may choose to wait until mDNS_ExitNow() returns true before calling mDNS_FinalExit().
//
// Call mDNS_Register with a completed AuthRecord object to register a resource record
// If the resource record type is kDNSRecordTypeUnique (or kDNSknownunique) then if a conflicting resource record is discovered,
// the resource record's mDNSRecordCallback will be called with error code mStatus_NameConflict. The callback should deregister
// the record, and may then try registering the record again after picking a new name (e.g. by automatically appending a number).
// Following deregistration, the RecordCallback will be called with result mStatus_MemFree to signal that it is safe to deallocate
// the record's storage (memory must be freed asynchronously to allow for goodbye packets and dynamic update deregistration).
//
// Call mDNS_StartQuery to initiate a query. mDNS will proceed to issue Multicast DNS query packets, and any time a response
// is received containing a record which matches the question, the DNSQuestion's mDNSAnswerCallback function will be called
// Call mDNS_StopQuery when no more answers are required
//
// Care should be taken on multi-threaded or interrupt-driven environments.
// The main mDNS routines call mDNSPlatformLock() on entry and mDNSPlatformUnlock() on exit;
// each platform layer needs to implement these appropriately for its respective platform.
// For example, if the support code on a particular platform implements timer callbacks at interrupt time, then
// mDNSPlatformLock/Unlock need to disable interrupts or do similar concurrency control to ensure that the mDNS
// code is not entered by an interrupt-time timer callback while in the middle of processing a client call.

extern mStatus mDNS_Init      (mDNS *const m, mDNS_PlatformSupport *const p,
								CacheEntity *rrcachestorage, mDNSu32 rrcachesize,
								mDNSBool AdvertiseLocalAddresses,
								mDNSCallback *Callback, void *Context);
// See notes above on use of NoCache/ZeroCacheSize
#define mDNS_Init_NoCache                     mDNSNULL
#define mDNS_Init_ZeroCacheSize               0
// See notes above on use of Advertise/DontAdvertiseLocalAddresses
#define mDNS_Init_AdvertiseLocalAddresses     mDNStrue
#define mDNS_Init_DontAdvertiseLocalAddresses mDNSfalse
#define mDNS_Init_NoInitCallback              mDNSNULL
#define mDNS_Init_NoInitCallbackContext       mDNSNULL

extern void    mDNS_ConfigChanged(mDNS *const m);
extern void    mDNS_GrowCache (mDNS *const m, CacheEntity *storage, mDNSu32 numrecords);
extern void    mDNS_GrowAuth (mDNS *const m, AuthEntity *storage, mDNSu32 numrecords);
extern void    mDNS_StartExit (mDNS *const m);
extern void    mDNS_FinalExit (mDNS *const m);
#define mDNS_Close(m) do { mDNS_StartExit(m); mDNS_FinalExit(m); } while(0)
#define mDNS_ExitNow(m, now) ((now) - (m)->ShutdownTime >= 0 || (!(m)->ResourceRecords))

extern mDNSs32 mDNS_Execute   (mDNS *const m);

extern mStatus mDNS_Register  (mDNS *const m, AuthRecord *const rr);
extern mStatus mDNS_Update    (mDNS *const m, AuthRecord *const rr, mDNSu32 newttl,
								const mDNSu16 newrdlength, RData *const newrdata, mDNSRecordUpdateCallback *Callback);
extern mStatus mDNS_Deregister(mDNS *const m, AuthRecord *const rr);

extern mStatus mDNS_StartQuery(mDNS *const m, DNSQuestion *const question);
extern mStatus mDNS_StopQuery (mDNS *const m, DNSQuestion *const question);
extern mStatus mDNS_StopQueryWithRemoves(mDNS *const m, DNSQuestion *const question);
extern mStatus mDNS_Reconfirm (mDNS *const m, CacheRecord *const cacherr);
extern mStatus mDNS_ReconfirmByValue(mDNS *const m, ResourceRecord *const rr);
extern void    mDNS_PurgeCacheResourceRecord(mDNS *const m, CacheRecord *rr);
extern mDNSs32 mDNS_TimeNow(const mDNS *const m);

extern mStatus mDNS_StartNATOperation(mDNS *const m, NATTraversalInfo *traversal);
extern mStatus mDNS_StopNATOperation(mDNS *const m, NATTraversalInfo *traversal);
extern mStatus mDNS_StopNATOperation_internal(mDNS *m, NATTraversalInfo *traversal);

extern DomainAuthInfo *GetAuthInfoForName(mDNS *m, const domainname *const name);

extern void    mDNS_UpdateAllowSleep(mDNS *const m);

// ***************************************************************************
#if 0
#pragma mark -
#pragma mark - Platform support functions that are accessible to the client layer too
#endif

extern mDNSs32  mDNSPlatformOneSecond;

// ***************************************************************************
#if 0
#pragma mark -
#pragma mark - General utility and helper functions
#endif

// mDNS_Dereg_normal is used for most calls to mDNS_Deregister_internal
// mDNS_Dereg_rapid is used to send one goodbye instead of three, when we want the memory available for reuse sooner
// mDNS_Dereg_conflict is used to indicate that this record is being forcibly deregistered because of a conflict
// mDNS_Dereg_repeat is used when cleaning up, for records that may have already been forcibly deregistered
typedef enum { mDNS_Dereg_normal, mDNS_Dereg_rapid, mDNS_Dereg_conflict, mDNS_Dereg_repeat } mDNS_Dereg_type;

// mDNS_RegisterService is a single call to register the set of resource records associated with a given named service.
//
// mDNS_StartResolveService is single call which is equivalent to multiple calls to mDNS_StartQuery,
// to find the IP address, port number, and demultiplexing information for a given named service.
// As with mDNS_StartQuery, it executes asynchronously, and calls the ServiceInfoQueryCallback when the answer is
// found. After the service is resolved, the client should call mDNS_StopResolveService to complete the transaction.
// The client can also call mDNS_StopResolveService at any time to abort the transaction.
//
// mDNS_AddRecordToService adds an additional record to a Service Record Set.  This record may be deregistered
// via mDNS_RemoveRecordFromService, or by deregistering the service.  mDNS_RemoveRecordFromService is passed a
// callback to free the memory associated with the extra RR when it is safe to do so.  The ExtraResourceRecord
// object can be found in the record's context pointer.

// mDNS_GetBrowseDomains is a special case of the mDNS_StartQuery call, where the resulting answers
// are a list of PTR records indicating (in the rdata) domains that are recommended for browsing.
// After getting the list of domains to browse, call mDNS_StopQuery to end the search.
// mDNS_GetDefaultBrowseDomain returns the name of the domain that should be highlighted by default.
//
// mDNS_GetRegistrationDomains and mDNS_GetDefaultRegistrationDomain are the equivalent calls to get the list
// of one or more domains that should be offered to the user as choices for where they may register their service,
// and the default domain in which to register in the case where the user has made no selection.

extern void    mDNS_SetupResourceRecord(AuthRecord *rr, RData *RDataStorage, mDNSInterfaceID InterfaceID,
               mDNSu16 rrtype, mDNSu32 ttl, mDNSu8 RecordType, AuthRecType artype, mDNSRecordCallback Callback, void *Context);

// mDNS_RegisterService() flags parameter bit definitions
enum
	{
		regFlagIncludeP2P	= 0x1,	// include P2P interfaces when using mDNSInterface_Any
		regFlagKnownUnique	= 0x2	// client guarantees that SRV and TXT record names are unique
	};

extern mStatus mDNS_RegisterService  (mDNS *const m, ServiceRecordSet *sr,
               const domainlabel *const name, const domainname *const type, const domainname *const domain,
               const domainname *const host, mDNSIPPort port, const mDNSu8 txtinfo[], mDNSu16 txtlen,
               AuthRecord *SubTypes, mDNSu32 NumSubTypes,
               mDNSInterfaceID InterfaceID, mDNSServiceCallback Callback, void *Context, mDNSu32 flags);
extern mStatus mDNS_AddRecordToService(mDNS *const m, ServiceRecordSet *sr, ExtraResourceRecord *extra, RData *rdata, mDNSu32 ttl,  mDNSu32 includeP2P);
extern mStatus mDNS_RemoveRecordFromService(mDNS *const m, ServiceRecordSet *sr, ExtraResourceRecord *extra, mDNSRecordCallback MemFreeCallback, void *Context);
extern mStatus mDNS_RenameAndReregisterService(mDNS *const m, ServiceRecordSet *const sr, const domainlabel *newname);
extern mStatus mDNS_DeregisterService_drt(mDNS *const m, ServiceRecordSet *sr, mDNS_Dereg_type drt);
#define mDNS_DeregisterService(M,S) mDNS_DeregisterService_drt((M), (S), mDNS_Dereg_normal)

extern mStatus mDNS_RegisterNoSuchService(mDNS *const m, AuthRecord *const rr,
               const domainlabel *const name, const domainname *const type, const domainname *const domain,
               const domainname *const host,
               const mDNSInterfaceID InterfaceID, mDNSRecordCallback Callback, void *Context, mDNSBool includeP2P);
#define        mDNS_DeregisterNoSuchService mDNS_Deregister

extern void mDNS_SetupQuestion(DNSQuestion *const q, const mDNSInterfaceID InterfaceID, const domainname *const name,
               const mDNSu16 qtype, mDNSQuestionCallback *const callback, void *const context);

extern mStatus mDNS_StartBrowse(mDNS *const m, DNSQuestion *const question,
               const domainname *const srv, const domainname *const domain,
               const mDNSInterfaceID InterfaceID, mDNSBool ForceMCast, mDNSQuestionCallback *Callback, void *Context);
#define        mDNS_StopBrowse mDNS_StopQuery

extern mStatus mDNS_StartResolveService(mDNS *const m, ServiceInfoQuery *query, ServiceInfo *info, mDNSServiceInfoQueryCallback *Callback, void *Context);
extern void    mDNS_StopResolveService (mDNS *const m, ServiceInfoQuery *query);

typedef enum
	{
	mDNS_DomainTypeBrowse              = 0,
	mDNS_DomainTypeBrowseDefault       = 1,
	mDNS_DomainTypeBrowseAutomatic     = 2,
	mDNS_DomainTypeRegistration        = 3,
	mDNS_DomainTypeRegistrationDefault = 4,

	mDNS_DomainTypeMax = 4
	} mDNS_DomainType;

extern const char *const mDNS_DomainTypeNames[];

extern mStatus mDNS_GetDomains(mDNS *const m, DNSQuestion *const question, mDNS_DomainType DomainType, const domainname *dom,
								const mDNSInterfaceID InterfaceID, mDNSQuestionCallback *Callback, void *Context);
#define        mDNS_StopGetDomains mDNS_StopQuery
extern mStatus mDNS_AdvertiseDomains(mDNS *const m, AuthRecord *rr, mDNS_DomainType DomainType, const mDNSInterfaceID InterfaceID, char *domname);
#define        mDNS_StopAdvertiseDomains mDNS_Deregister

extern mDNSOpaque16 mDNS_NewMessageID(mDNS *const m);
extern mDNSBool mDNS_AddressIsLocalSubnet(mDNS *const m, const mDNSInterfaceID InterfaceID, const mDNSAddr *addr);

extern DNSServer *GetServerForName(mDNS *m, const domainname *name, mDNSInterfaceID InterfaceID);
extern DNSServer *GetServerForQuestion(mDNS *m, DNSQuestion *question);
extern mDNSu32 SetValidDNSServers(mDNS *m, DNSQuestion *question);

// ***************************************************************************
#if 0
#pragma mark -
#pragma mark - DNS name utility functions
#endif

// In order to expose the full capabilities of the DNS protocol (which allows any arbitrary eight-bit values
// in domain name labels, including unlikely characters like ascii nulls and even dots) all the mDNS APIs
// work with DNS's native length-prefixed strings. For convenience in C, the following utility functions
// are provided for converting between C's null-terminated strings and DNS's length-prefixed strings.

// Assignment
// A simple C structure assignment of a domainname can cause a protection fault by accessing unmapped memory,
// because that object is defined to be 256 bytes long, but not all domainname objects are truly the full size.
// This macro uses mDNSPlatformMemCopy() to make sure it only touches the actual bytes that are valid.
#define AssignDomainName(DST, SRC) do { mDNSu16 len__ = DomainNameLength((SRC)); \
	if (len__ <= MAX_DOMAIN_NAME) mDNSPlatformMemCopy((DST)->c, (SRC)->c, len__); else (DST)->c[0] = 0; } while(0)

// Comparison functions
#define SameDomainLabelCS(A,B) ((A)[0] == (B)[0] && mDNSPlatformMemSame((A)+1, (B)+1, (A)[0]))
extern mDNSBool SameDomainLabel(const mDNSu8 *a, const mDNSu8 *b);
extern mDNSBool SameDomainName(const domainname *const d1, const domainname *const d2);
extern mDNSBool SameDomainNameCS(const domainname *const d1, const domainname *const d2);
typedef mDNSBool DomainNameComparisonFn(const domainname *const d1, const domainname *const d2);
extern mDNSBool IsLocalDomain(const domainname *d);     // returns true for domains that by default should be looked up using link-local multicast

#define StripFirstLabel(X) ((const domainname *)&(X)->c[(X)->c[0] ? 1 + (X)->c[0] : 0])

#define FirstLabel(X)  ((const domainlabel *)(X))
#define SecondLabel(X) ((const domainlabel *)StripFirstLabel(X))
#define ThirdLabel(X)  ((const domainlabel *)StripFirstLabel(StripFirstLabel(X)))

extern const mDNSu8 *LastLabel(const domainname *d);

// Get total length of domain name, in native DNS format, including terminal root label
//   (e.g. length of "com." is 5 (length byte, three data bytes, final zero)
extern mDNSu16  DomainNameLengthLimit(const domainname *const name, const mDNSu8 *limit);
#define DomainNameLength(name) DomainNameLengthLimit((name), (name)->c + MAX_DOMAIN_NAME)

// Append functions to append one or more labels to an existing native format domain name:
//   AppendLiteralLabelString adds a single label from a literal C string, with no escape character interpretation.
//   AppendDNSNameString      adds zero or more labels from a C string using conventional DNS dots-and-escaping interpretation
//   AppendDomainLabel        adds a single label from a native format domainlabel
//   AppendDomainName         adds zero or more labels from a native format domainname
extern mDNSu8  *AppendLiteralLabelString(domainname *const name, const char *cstr);
extern mDNSu8  *AppendDNSNameString     (domainname *const name, const char *cstr);
extern mDNSu8  *AppendDomainLabel       (domainname *const name, const domainlabel *const label);
extern mDNSu8  *AppendDomainName        (domainname *const name, const domainname *const append);

// Convert from null-terminated string to native DNS format:
//   The DomainLabel form makes a single label from a literal C string, with no escape character interpretation.
//   The DomainName form makes native format domain name from a C string using conventional DNS interpretation:
//     dots separate labels, and within each label, '\.' represents a literal dot, '\\' represents a literal
//     backslash and backslash with three decimal digits (e.g. \000) represents an arbitrary byte value.
extern mDNSBool MakeDomainLabelFromLiteralString(domainlabel *const label, const char *cstr);
extern mDNSu8  *MakeDomainNameFromDNSNameString (domainname  *const name,  const char *cstr);

// Convert native format domainlabel or domainname back to C string format
// IMPORTANT:
// When using ConvertDomainLabelToCString, the target buffer must be MAX_ESCAPED_DOMAIN_LABEL (254) bytes long
// to guarantee there will be no buffer overrun. It is only safe to use a buffer shorter than this in rare cases
// where the label is known to be constrained somehow (for example, if the label is known to be either "_tcp" or "_udp").
// Similarly, when using ConvertDomainNameToCString, the target buffer must be MAX_ESCAPED_DOMAIN_NAME (1009) bytes long.
// See definitions of MAX_ESCAPED_DOMAIN_LABEL and MAX_ESCAPED_DOMAIN_NAME for more detailed explanation.
extern char    *ConvertDomainLabelToCString_withescape(const domainlabel *const name, char *cstr, char esc);
#define         ConvertDomainLabelToCString_unescaped(D,C) ConvertDomainLabelToCString_withescape((D), (C), 0)
#define         ConvertDomainLabelToCString(D,C)           ConvertDomainLabelToCString_withescape((D), (C), '\\')
extern char    *ConvertDomainNameToCString_withescape(const domainname *const name, char *cstr, char esc);
#define         ConvertDomainNameToCString_unescaped(D,C) ConvertDomainNameToCString_withescape((D), (C), 0)
#define         ConvertDomainNameToCString(D,C)           ConvertDomainNameToCString_withescape((D), (C), '\\')

extern void     ConvertUTF8PstringToRFC1034HostLabel(const mDNSu8 UTF8Name[], domainlabel *const hostlabel);

extern mDNSu8  *ConstructServiceName(domainname *const fqdn, const domainlabel *name, const domainname *type, const domainname *const domain);
extern mDNSBool DeconstructServiceName(const domainname *const fqdn, domainlabel *const name, domainname *const type, domainname *const domain);

// Note: Some old functions have been replaced by more sensibly-named versions.
// You can uncomment the hash-defines below if you don't want to have to change your source code right away.
// When updating your code, note that (unlike the old versions) *all* the new routines take the target object
// as their first parameter.
//#define ConvertCStringToDomainName(SRC,DST)  MakeDomainNameFromDNSNameString((DST),(SRC))
//#define ConvertCStringToDomainLabel(SRC,DST) MakeDomainLabelFromLiteralString((DST),(SRC))
//#define AppendStringLabelToName(DST,SRC)     AppendLiteralLabelString((DST),(SRC))
//#define AppendStringNameToName(DST,SRC)      AppendDNSNameString((DST),(SRC))
//#define AppendDomainLabelToName(DST,SRC)     AppendDomainLabel((DST),(SRC))
//#define AppendDomainNameToName(DST,SRC)      AppendDomainName((DST),(SRC))

// ***************************************************************************
#if 0
#pragma mark -
#pragma mark - Other utility functions and macros
#endif

// mDNS_vsnprintf/snprintf return the number of characters written, excluding the final terminating null.
// The output is always null-terminated: for example, if the output turns out to be exactly buflen long,
// then the output will be truncated by one character to allow space for the terminating null.
// Unlike standard C vsnprintf/snprintf, they return the number of characters *actually* written,
// not the number of characters that *would* have been printed were buflen unlimited.
extern mDNSu32 mDNS_vsnprintf(char *sbuffer, mDNSu32 buflen, const char *fmt, va_list arg);
extern mDNSu32 mDNS_snprintf(char *sbuffer, mDNSu32 buflen, const char *fmt, ...) IS_A_PRINTF_STYLE_FUNCTION(3,4);
extern mDNSu32 NumCacheRecordsForInterfaceID(const mDNS *const m, mDNSInterfaceID id);
extern char *DNSTypeName(mDNSu16 rrtype);
extern char *GetRRDisplayString_rdb(const ResourceRecord *const rr, const RDataBody *const rd1, char *const buffer);
#define RRDisplayString(m, rr) GetRRDisplayString_rdb(rr, &(rr)->rdata->u, (m)->MsgBuffer)
#define ARDisplayString(m, rr) GetRRDisplayString_rdb(&(rr)->resrec, &(rr)->resrec.rdata->u, (m)->MsgBuffer)
#define CRDisplayString(m, rr) GetRRDisplayString_rdb(&(rr)->resrec, &(rr)->resrec.rdata->u, (m)->MsgBuffer)
extern mDNSBool mDNSSameAddress(const mDNSAddr *ip1, const mDNSAddr *ip2);
extern void IncrementLabelSuffix(domainlabel *name, mDNSBool RichText);
extern mDNSBool mDNSv4AddrIsRFC1918(mDNSv4Addr *addr);  // returns true for RFC1918 private addresses
#define mDNSAddrIsRFC1918(X) ((X)->type == mDNSAddrType_IPv4 && mDNSv4AddrIsRFC1918(&(X)->ip.v4))

#define mDNSSameIPPort(A,B)      ((A).NotAnInteger == (B).NotAnInteger)
#define mDNSSameOpaque16(A,B)    ((A).NotAnInteger == (B).NotAnInteger)
#define mDNSSameOpaque32(A,B)    ((A).NotAnInteger == (B).NotAnInteger)
#define mDNSSameOpaque64(A,B)    ((A)->l[0] == (B)->l[0] && (A)->l[1] == (B)->l[1])

#define mDNSSameIPv4Address(A,B) ((A).NotAnInteger == (B).NotAnInteger)
#define mDNSSameIPv6Address(A,B) ((A).l[0] == (B).l[0] && (A).l[1] == (B).l[1] && (A).l[2] == (B).l[2] && (A).l[3] == (B).l[3])
#define mDNSSameEthAddress(A,B)  ((A)->w[0] == (B)->w[0] && (A)->w[1] == (B)->w[1] && (A)->w[2] == (B)->w[2])

#define mDNSIPPortIsZero(A)      ((A).NotAnInteger                            == 0)
#define mDNSOpaque16IsZero(A)    ((A).NotAnInteger                            == 0)
#define mDNSOpaque64IsZero(A)    (((A)->l[0] | (A)->l[1]                    ) == 0)
#define mDNSIPv4AddressIsZero(A) ((A).NotAnInteger                            == 0)
#define mDNSIPv6AddressIsZero(A) (((A).l[0] | (A).l[1] | (A).l[2] | (A).l[3]) == 0)
#define mDNSEthAddressIsZero(A)  (((A).w[0] | (A).w[1] | (A).w[2]           ) == 0)

#define mDNSIPv4AddressIsOnes(A) ((A).NotAnInteger == 0xFFFFFFFF)
#define mDNSIPv6AddressIsOnes(A) (((A).l[0] & (A).l[1] & (A).l[2] & (A).l[3]) == 0xFFFFFFFF)

#define mDNSAddressIsAllDNSLinkGroup(X) (                                                            \
	((X)->type == mDNSAddrType_IPv4 && mDNSSameIPv4Address((X)->ip.v4, AllDNSLinkGroup_v4.ip.v4)) || \
	((X)->type == mDNSAddrType_IPv6 && mDNSSameIPv6Address((X)->ip.v6, AllDNSLinkGroup_v6.ip.v6))    )

#define mDNSAddressIsZero(X) (                                                \
	((X)->type == mDNSAddrType_IPv4 && mDNSIPv4AddressIsZero((X)->ip.v4))  || \
	((X)->type == mDNSAddrType_IPv6 && mDNSIPv6AddressIsZero((X)->ip.v6))     )

#define mDNSAddressIsValidNonZero(X) (                                        \
	((X)->type == mDNSAddrType_IPv4 && !mDNSIPv4AddressIsZero((X)->ip.v4)) || \
	((X)->type == mDNSAddrType_IPv6 && !mDNSIPv6AddressIsZero((X)->ip.v6))    )

#define mDNSAddressIsOnes(X) (                                                \
	((X)->type == mDNSAddrType_IPv4 && mDNSIPv4AddressIsOnes((X)->ip.v4))  || \
	((X)->type == mDNSAddrType_IPv6 && mDNSIPv6AddressIsOnes((X)->ip.v6))     )

#define mDNSAddressIsValid(X) (                                                                                \
	((X)->type == mDNSAddrType_IPv4) ? !(mDNSIPv4AddressIsZero((X)->ip.v4) || mDNSIPv4AddressIsOnes((X)->ip.v4)) :          \
	((X)->type == mDNSAddrType_IPv6) ? !(mDNSIPv6AddressIsZero((X)->ip.v6) || mDNSIPv6AddressIsOnes((X)->ip.v6)) : mDNSfalse)

#define mDNSv4AddressIsLinkLocal(X) ((X)->b[0] ==  169 &&  (X)->b[1]         ==  254)
#define mDNSv6AddressIsLinkLocal(X) ((X)->b[0] == 0xFE && ((X)->b[1] & 0xC0) == 0x80)

#define mDNSAddressIsLinkLocal(X)  (                                                    \
	((X)->type == mDNSAddrType_IPv4) ? mDNSv4AddressIsLinkLocal(&(X)->ip.v4) :          \
	((X)->type == mDNSAddrType_IPv6) ? mDNSv6AddressIsLinkLocal(&(X)->ip.v6) : mDNSfalse)

#define mDNSv4AddressIsLoopback(X) ((X)->b[0] == 127 && (X)->b[1] == 0 && (X)->b[2] == 0 && (X)->b[3] == 1)
#define mDNSv6AddressIsLoopback(X) ((((X)->l[0] | (X)->l[1] | (X)->l[2]) == 0) && ((X)->b[12] == 0 && (X)->b[13] == 0 && (X)->b[14] == 0 && (X)->b[15] == 1))

// ***************************************************************************
#if 0
#pragma mark -
#pragma mark - Authentication Support
#endif

// Unicast DNS and Dynamic Update specific Client Calls
//
// mDNS_SetSecretForDomain tells the core to authenticate (via TSIG with an HMAC_MD5 hash of the shared secret)
// when dynamically updating a given zone (and its subdomains).  The key used in authentication must be in
// domain name format.  The shared secret must be a null-terminated base64 encoded string.  A minimum size of
// 16 bytes (128 bits) is recommended for an MD5 hash as per RFC 2485.
// Calling this routine multiple times for a zone replaces previously entered values.  Call with a NULL key
// to disable authentication for the zone.  A non-NULL autoTunnelPrefix means this is an AutoTunnel domain,
// and the value is prepended to the IPSec identifier (used for key lookup)

extern mStatus mDNS_SetSecretForDomain(mDNS *m, DomainAuthInfo *info,
	const domainname *domain, const domainname *keyname, const char *b64keydata, const domainname *hostname, mDNSIPPort *port, const char *autoTunnelPrefix);

extern void RecreateNATMappings(mDNS *const m);

// Hostname/Unicast Interface Configuration

// All hostnames advertised point to one IPv4 address and/or one IPv6 address, set via SetPrimaryInterfaceInfo.  Invoking this routine
// updates all existing hostnames to point to the new address.

// A hostname is added via AddDynDNSHostName, which points to the primary interface's v4 and/or v6 addresss

// The status callback is invoked to convey success or failure codes - the callback should not modify the AuthRecord or free memory.
// Added hostnames may be removed (deregistered) via mDNS_RemoveDynDNSHostName.

// Host domains added prior to specification of the primary interface address and computer name will be deferred until
// these values are initialized.

// DNS servers used to resolve unicast queries are specified by mDNS_AddDNSServer.
// For "split" DNS configurations, in which queries for different domains are sent to different servers (e.g. VPN and external),
// a domain may be associated with a DNS server.  For standard configurations, specify the root label (".") or NULL.

extern void mDNS_AddDynDNSHostName(mDNS *m, const domainname *fqdn, mDNSRecordCallback *StatusCallback, const void *StatusContext);
extern void mDNS_RemoveDynDNSHostName(mDNS *m, const domainname *fqdn);
extern void mDNS_SetPrimaryInterfaceInfo(mDNS *m, const mDNSAddr *v4addr,  const mDNSAddr *v6addr, const mDNSAddr *router);
extern DNSServer *mDNS_AddDNSServer(mDNS *const m, const domainname *d, const mDNSInterfaceID interface, const mDNSAddr *addr, const mDNSIPPort port, mDNSBool scoped, mDNSu32 timeout);
extern void PenalizeDNSServer(mDNS *const m, DNSQuestion *q);
extern void mDNS_AddSearchDomain(const domainname *const domain, mDNSInterfaceID InterfaceID);

extern McastResolver *mDNS_AddMcastResolver(mDNS *const m, const domainname *d, const mDNSInterfaceID interface, mDNSu32 timeout);

// We use ((void *)0) here instead of mDNSNULL to avoid compile warnings on gcc 4.2
#define mDNS_AddSearchDomain_CString(X, I) \
	do { domainname d__; if (((X) != (void*)0) && MakeDomainNameFromDNSNameString(&d__, (X)) && d__.c[0]) mDNS_AddSearchDomain(&d__, I); } while(0)

// Routines called by the core, exported by DNSDigest.c

// Convert an arbitrary base64 encoded key key into an HMAC key (stored in AuthInfo struct)
extern mDNSs32 DNSDigest_ConstructHMACKeyfromBase64(DomainAuthInfo *info, const char *b64key);

// sign a DNS message.  The message must be complete, with all values in network byte order.  end points to the end
// of the message, and is modified by this routine.  numAdditionals is a pointer to the number of additional
// records in HOST byte order, which is incremented upon successful completion of this routine.  The function returns
// the new end pointer on success, and NULL on failure.
extern void DNSDigest_SignMessage(DNSMessage *msg, mDNSu8 **end, DomainAuthInfo *info, mDNSu16 tcode);

#define SwapDNSHeaderBytes(M) do { \
    (M)->h.numQuestions   = (mDNSu16)((mDNSu8 *)&(M)->h.numQuestions  )[0] << 8 | ((mDNSu8 *)&(M)->h.numQuestions  )[1]; \
    (M)->h.numAnswers     = (mDNSu16)((mDNSu8 *)&(M)->h.numAnswers    )[0] << 8 | ((mDNSu8 *)&(M)->h.numAnswers    )[1]; \
    (M)->h.numAuthorities = (mDNSu16)((mDNSu8 *)&(M)->h.numAuthorities)[0] << 8 | ((mDNSu8 *)&(M)->h.numAuthorities)[1]; \
    (M)->h.numAdditionals = (mDNSu16)((mDNSu8 *)&(M)->h.numAdditionals)[0] << 8 | ((mDNSu8 *)&(M)->h.numAdditionals)[1]; \
    } while (0)

#define DNSDigest_SignMessageHostByteOrder(M,E,INFO) \
	do { SwapDNSHeaderBytes(M); DNSDigest_SignMessage((M), (E), (INFO), 0); SwapDNSHeaderBytes(M); } while (0)

// verify a DNS message.  The message must be complete, with all values in network byte order.  end points to the
// end of the record.  tsig is a pointer to the resource record that contains the TSIG OPT record.  info is
// the matching key to use for verifying the message.  This function expects that the additionals member
// of the DNS message header has already had one subtracted from it.
extern mDNSBool DNSDigest_VerifyMessage(DNSMessage *msg, mDNSu8 *end, LargeCacheRecord *tsig, DomainAuthInfo *info, mDNSu16 *rcode, mDNSu16 *tcode);

// ***************************************************************************
#if 0
#pragma mark -
#pragma mark - PlatformSupport interface
#endif

// This section defines the interface to the Platform Support layer.
// Normal client code should not use any of types defined here, or directly call any of the functions defined here.
// The definitions are placed here because sometimes clients do use these calls indirectly, via other supported client operations.
// For example, AssignDomainName is a macro defined using mDNSPlatformMemCopy()

// Every platform support module must provide the following functions.
// mDNSPlatformInit() typically opens a communication endpoint, and starts listening for mDNS packets.
// When Setup is complete, the platform support layer calls mDNSCoreInitComplete().
// mDNSPlatformSendUDP() sends one UDP packet
// When a packet is received, the PlatformSupport code calls mDNSCoreReceive()
// mDNSPlatformClose() tidies up on exit
//
// Note: mDNSPlatformMemAllocate/mDNSPlatformMemFree are only required for handling oversized resource records and unicast DNS.
// If your target platform has a well-defined specialized application, and you know that all the records it uses
// are InlineCacheRDSize or less, then you can just make a simple mDNSPlatformMemAllocate() stub that always returns
// NULL. InlineCacheRDSize is a compile-time constant, which is set by default to 68. If you need to handle records
// a little larger than this and you don't want to have to implement run-time allocation and freeing, then you
// can raise the value of this constant to a suitable value (at the expense of increased memory usage).
//
// USE CAUTION WHEN CALLING mDNSPlatformRawTime: The m->timenow_adjust correction factor needs to be added
// Generally speaking:
// Code that's protected by the main mDNS lock should just use the m->timenow value
// Code outside the main mDNS lock should use mDNS_TimeNow(m) to get properly adjusted time
// In certain cases there may be reasons why it's necessary to get the time without taking the lock first
// (e.g. inside the routines that are doing the locking and unlocking, where a call to get the lock would result in a
// recursive loop); in these cases use mDNS_TimeNow_NoLock(m) to get mDNSPlatformRawTime with the proper correction factor added.
//
// mDNSPlatformUTC returns the time, in seconds, since Jan 1st 1970 UTC and is required for generating TSIG records

extern mStatus  mDNSPlatformInit        (mDNS *const m);
extern void     mDNSPlatformClose       (mDNS *const m);
extern mStatus  mDNSPlatformSendUDP(const mDNS *const m, const void *const msg, const mDNSu8 *const end,
mDNSInterfaceID InterfaceID, UDPSocket *src, const mDNSAddr *dst, mDNSIPPort dstport);

extern void     mDNSPlatformLock        (const mDNS *const m);
extern void     mDNSPlatformUnlock      (const mDNS *const m);

extern void     mDNSPlatformStrCopy     (      void *dst, const void *src);
extern mDNSu32  mDNSPlatformStrLen      (                 const void *src);
extern void     mDNSPlatformMemCopy     (      void *dst, const void *src, mDNSu32 len);
extern mDNSBool mDNSPlatformMemSame     (const void *dst, const void *src, mDNSu32 len);
extern void     mDNSPlatformMemZero     (      void *dst,                  mDNSu32 len);
#if APPLE_OSX_mDNSResponder && MACOSX_MDNS_MALLOC_DEBUGGING
#define         mDNSPlatformMemAllocate(X) mallocL(#X, X)
#else
extern void *   mDNSPlatformMemAllocate (mDNSu32 len);
#endif
extern void     mDNSPlatformMemFree     (void *mem);

// If the platform doesn't have a strong PRNG, we define a naive multiply-and-add based on a seed
// from the platform layer.  Long-term, we should embed an arc4 implementation, but the strength
// will still depend on the randomness of the seed.
#if !defined(_PLATFORM_HAS_STRONG_PRNG_) && (_BUILDING_XCODE_PROJECT_ || defined(_WIN32))
#define _PLATFORM_HAS_STRONG_PRNG_ 1
#endif
#if _PLATFORM_HAS_STRONG_PRNG_
extern mDNSu32  mDNSPlatformRandomNumber(void);
#else
extern mDNSu32  mDNSPlatformRandomSeed  (void);
#endif // _PLATFORM_HAS_STRONG_PRNG_

extern mStatus  mDNSPlatformTimeInit    (void);
extern mDNSs32  mDNSPlatformRawTime     (void);
extern mDNSs32  mDNSPlatformUTC         (void);
#define mDNS_TimeNow_NoLock(m) (mDNSPlatformRawTime() + (m)->timenow_adjust)

#if MDNS_DEBUGMSGS
extern void	mDNSPlatformWriteDebugMsg(const char *msg);
#endif
extern void	mDNSPlatformWriteLogMsg(const char *ident, const char *msg, mDNSLogLevel_t loglevel);

#if APPLE_OSX_mDNSResponder
// Utility function for ASL logging
mDNSexport void mDNSASLLog(uuid_t *uuid, const char *subdomain, const char *result, const char *signature, const char *fmt, ...);
#endif

// Platform support modules should provide the following functions to map between opaque interface IDs
// and interface indexes in order to support the DNS-SD API. If your target platform does not support
// multiple interfaces and/or does not support the DNS-SD API, these functions can be empty.
extern mDNSInterfaceID mDNSPlatformInterfaceIDfromInterfaceIndex(mDNS *const m, mDNSu32 ifindex);
extern mDNSu32 mDNSPlatformInterfaceIndexfromInterfaceID(mDNS *const m, mDNSInterfaceID id, mDNSBool suppressNetworkChange);

// Every platform support module must provide the following functions if it is to support unicast DNS
// and Dynamic Update.
// All TCP socket operations implemented by the platform layer MUST NOT BLOCK.
// mDNSPlatformTCPConnect initiates a TCP connection with a peer, adding the socket descriptor to the
// main event loop.  The return value indicates whether the connection succeeded, failed, or is pending
// (i.e. the call would block.)  On return, the descriptor parameter is set to point to the connected socket.
// The TCPConnectionCallback is subsequently invoked when the connection
// completes (in which case the ConnectionEstablished parameter is true), or data is available for
// reading on the socket (indicated by the ConnectionEstablished parameter being false.)  If the connection
// asynchronously fails, the TCPConnectionCallback should be invoked as usual, with the error being
// returned in subsequent calls to PlatformReadTCP or PlatformWriteTCP.  (This allows for platforms
// with limited asynchronous error detection capabilities.)  PlatformReadTCP and PlatformWriteTCP must
// return the number of bytes read/written, 0 if the call would block, and -1 if an error.  PlatformReadTCP
// should set the closed argument if the socket has been closed.
// PlatformTCPCloseConnection must close the connection to the peer and remove the descriptor from the
// event loop.  CloseConnectin may be called at any time, including in a ConnectionCallback.

typedef enum
	{
	kTCPSocketFlags_Zero   = 0,
	kTCPSocketFlags_UseTLS = (1 << 0)
	} TCPSocketFlags;

typedef void (*TCPConnectionCallback)(TCPSocket *sock, void *context, mDNSBool ConnectionEstablished, mStatus err);
extern TCPSocket *mDNSPlatformTCPSocket(mDNS *const m, TCPSocketFlags flags, mDNSIPPort *port);	// creates a TCP socket
extern TCPSocket *mDNSPlatformTCPAccept(TCPSocketFlags flags, int sd);
extern int        mDNSPlatformTCPGetFD(TCPSocket *sock);
extern mStatus    mDNSPlatformTCPConnect(TCPSocket *sock, const mDNSAddr *dst, mDNSOpaque16 dstport, domainname *hostname,
										mDNSInterfaceID InterfaceID, TCPConnectionCallback callback, void *context);
extern void       mDNSPlatformTCPCloseConnection(TCPSocket *sock);
extern long       mDNSPlatformReadTCP(TCPSocket *sock, void *buf, unsigned long buflen, mDNSBool *closed);
extern long       mDNSPlatformWriteTCP(TCPSocket *sock, const char *msg, unsigned long len);
extern UDPSocket *mDNSPlatformUDPSocket(mDNS *const m, const mDNSIPPort requestedport);
extern void       mDNSPlatformUDPClose(UDPSocket *sock);
extern void       mDNSPlatformReceiveBPF_fd(mDNS *const m, int fd);
extern void       mDNSPlatformUpdateProxyList(mDNS *const m, const mDNSInterfaceID InterfaceID);
extern void       mDNSPlatformSendRawPacket(const void *const msg, const mDNSu8 *const end, mDNSInterfaceID InterfaceID);
extern void       mDNSPlatformSetLocalAddressCacheEntry(mDNS *const m, const mDNSAddr *const tpa, const mDNSEthAddr *const tha, mDNSInterfaceID InterfaceID);
extern void       mDNSPlatformSourceAddrForDest(mDNSAddr *const src, const mDNSAddr *const dst);

// mDNSPlatformTLSSetupCerts/mDNSPlatformTLSTearDownCerts used by dnsextd
extern mStatus    mDNSPlatformTLSSetupCerts(void);
extern void       mDNSPlatformTLSTearDownCerts(void);

// Platforms that support unicast browsing and dynamic update registration for clients who do not specify a domain
// in browse/registration calls must implement these routines to get the "default" browse/registration list.

extern void       mDNSPlatformSetDNSConfig(mDNS *const m, mDNSBool setservers, mDNSBool setsearch, domainname *const fqdn, DNameListElem **RegDomains, DNameListElem **BrowseDomains);
extern mStatus    mDNSPlatformGetPrimaryInterface(mDNS *const m, mDNSAddr *v4, mDNSAddr *v6, mDNSAddr *router);
extern void       mDNSPlatformDynDNSHostNameStatusChanged(const domainname *const dname, const mStatus status);

extern void       mDNSPlatformSetAllowSleep(mDNS *const m, mDNSBool allowSleep, const char *reason);
extern void       mDNSPlatformSendWakeupPacket(mDNS *const m, mDNSInterfaceID InterfaceID, char *EthAddr, char *IPAddr, int iteration);
extern mDNSBool   mDNSPlatformValidRecordForInterface(AuthRecord *rr, const NetworkInterfaceInfo *intf);

#ifdef _LEGACY_NAT_TRAVERSAL_
// Support for legacy NAT traversal protocols, implemented by the platform layer and callable by the core.
extern void     LNT_SendDiscoveryMsg(mDNS *m);
extern void     LNT_ConfigureRouterInfo(mDNS *m, const mDNSInterfaceID InterfaceID, const mDNSu8 *const data, const mDNSu16 len);
extern mStatus  LNT_GetExternalAddress(mDNS *m);
extern mStatus  LNT_MapPort(mDNS *m, NATTraversalInfo *n);
extern mStatus  LNT_UnmapPort(mDNS *m, NATTraversalInfo *n);
extern void     LNT_ClearState(mDNS *const m);
#endif // _LEGACY_NAT_TRAVERSAL_

// The core mDNS code provides these functions, for the platform support code to call at appropriate times
//
// mDNS_SetFQDN() is called once on startup (typically from mDNSPlatformInit())
// and then again on each subsequent change of the host name.
//
// mDNS_RegisterInterface() is used by the platform support layer to inform mDNSCore of what
// physical and/or logical interfaces are available for sending and receiving packets.
// Typically it is called on startup for each available interface, but register/deregister may be
// called again later, on multiple occasions, to inform the core of interface configuration changes.
// If set->Advertise is set non-zero, then mDNS_RegisterInterface() also registers the standard
// resource records that should be associated with every publicised IP address/interface:
// -- Name-to-address records (A/AAAA)
// -- Address-to-name records (PTR)
// -- Host information (HINFO)
// IMPORTANT: The specified mDNSInterfaceID MUST NOT be 0, -1, or -2; these values have special meaning
// mDNS_RegisterInterface does not result in the registration of global hostnames via dynamic update -
// see mDNS_SetPrimaryInterfaceInfo, mDNS_AddDynDNSHostName, etc. for this purpose.
// Note that the set may be deallocated immediately after it is deregistered via mDNS_DeegisterInterface.
//
// mDNS_RegisterDNS() is used by the platform support layer to provide the core with the addresses of
// available domain name servers for unicast queries/updates.  RegisterDNS() should be called once for
// each name server, typically at startup, or when a new name server becomes available.  DeregiterDNS()
// must be called whenever a registered name server becomes unavailable.  DeregisterDNSList deregisters
// all registered servers.  mDNS_DNSRegistered() returns true if one or more servers are registered in the core.
//
// mDNSCoreInitComplete() is called when the platform support layer is finished.
// Typically this is at the end of mDNSPlatformInit(), but may be later
// (on platforms like OT that allow asynchronous initialization of the networking stack).
//
// mDNSCoreReceive() is called when a UDP packet is received
//
// mDNSCoreMachineSleep() is called when the machine sleeps or wakes
// (This refers to heavyweight laptop-style sleep/wake that disables network access,
// not lightweight second-by-second CPU power management modes.)

extern void     mDNS_SetFQDN(mDNS *const m);
extern void     mDNS_ActivateNetWake_internal  (mDNS *const m, NetworkInterfaceInfo *set);
extern void     mDNS_DeactivateNetWake_internal(mDNS *const m, NetworkInterfaceInfo *set);
extern mStatus  mDNS_RegisterInterface  (mDNS *const m, NetworkInterfaceInfo *set, mDNSBool flapping);
extern void     mDNS_DeregisterInterface(mDNS *const m, NetworkInterfaceInfo *set, mDNSBool flapping);
extern void     mDNSCoreInitComplete(mDNS *const m, mStatus result);
extern void     mDNSCoreReceive(mDNS *const m, void *const msg, const mDNSu8 *const end,
								const mDNSAddr *const srcaddr, const mDNSIPPort srcport,
								const mDNSAddr *dstaddr, const mDNSIPPort dstport, const mDNSInterfaceID InterfaceID);
extern void		mDNSCoreRestartQueries(mDNS *const m);
typedef void    (*FlushCache)(mDNS *const m);
typedef void    (*CallbackBeforeStartQuery)(mDNS *const m, void *context);
extern void		mDNSCoreRestartAddressQueries(mDNS *const m, mDNSBool SearchDomainsChanged, FlushCache flushCacheRecords,
											  CallbackBeforeStartQuery beforeQueryStart, void *context);
extern mDNSBool mDNSCoreHaveAdvertisedMulticastServices(mDNS *const m);
extern void     mDNSCoreMachineSleep(mDNS *const m, mDNSBool wake);
extern mDNSBool mDNSCoreReadyForSleep(mDNS *m, mDNSs32 now);
extern mDNSs32  mDNSCoreIntervalToNextWake(mDNS *const m, mDNSs32 now);

extern void     mDNSCoreReceiveRawPacket  (mDNS *const m, const mDNSu8 *const p, const mDNSu8 *const end, const mDNSInterfaceID InterfaceID);

extern mDNSBool mDNSAddrIsDNSMulticast(const mDNSAddr *ip);

extern CacheRecord *CreateNewCacheEntry(mDNS *const m, const mDNSu32 slot, CacheGroup *cg, mDNSs32 delay);
extern void ScheduleNextCacheCheckTime(mDNS *const m, const mDNSu32 slot, const mDNSs32 event);
extern void GrantCacheExtensions(mDNS *const m, DNSQuestion *q, mDNSu32 lease);
extern void MakeNegativeCacheRecord(mDNS *const m, CacheRecord *const cr,
	const domainname *const name, const mDNSu32 namehash, const mDNSu16 rrtype, const mDNSu16 rrclass, mDNSu32 ttl_seconds,
	mDNSInterfaceID InterfaceID, DNSServer *dnsserver);
extern void CompleteDeregistration(mDNS *const m, AuthRecord *rr);
extern void AnswerCurrentQuestionWithResourceRecord(mDNS *const m, CacheRecord *const rr, const QC_result AddRecord);
extern char *InterfaceNameForID(mDNS *const m, const mDNSInterfaceID InterfaceID);
extern void DNSServerChangeForQuestion(mDNS *const m, DNSQuestion *q, DNSServer *newServer);
extern void ActivateUnicastRegistration(mDNS *const m, AuthRecord *const rr);
extern void CheckSuppressUnusableQuestions(mDNS *const m);
extern void RetrySearchDomainQuestions(mDNS *const m);

// Used only in logging to restrict the number of /etc/hosts entries printed
extern void FreeEtcHosts(mDNS *const m, AuthRecord *const rr, mStatus result);
// exported for using the hash for /etc/hosts AuthRecords
extern AuthGroup *AuthGroupForName(AuthHash *r, const mDNSu32 slot, const mDNSu32 namehash, const domainname *const name);
extern AuthGroup *AuthGroupForRecord(AuthHash *r, const mDNSu32 slot, const ResourceRecord *const rr);
extern AuthGroup *InsertAuthRecord(mDNS *const m, AuthHash *r, AuthRecord *rr);
extern AuthGroup *RemoveAuthRecord(mDNS *const m, AuthHash *r, AuthRecord *rr);

// For now this AutoTunnel stuff is specific to Mac OS X.
// In the future, if there's demand, we may see if we can abstract it out cleanly into the platform layer
#if APPLE_OSX_mDNSResponder
extern void AutoTunnelCallback(mDNS *const m, DNSQuestion *question, const ResourceRecord *const answer, QC_result AddRecord);
extern void AddNewClientTunnel(mDNS *const m, DNSQuestion *const q);
extern void SetupLocalAutoTunnelInterface_internal(mDNS *const m, mDNSBool servicesStarting);
extern void UpdateAutoTunnelDomainStatuses(const mDNS *const m);
extern mStatus ActivateLocalProxy(mDNS *const m, char *ifname);
extern void RemoveAutoTunnel6Record(mDNS *const m);
extern mDNSBool RecordReadyForSleep(mDNS *const m, AuthRecord *rr);
#endif

// ***************************************************************************
#if 0
#pragma mark -
#pragma mark - Sleep Proxy
#endif

// Sleep Proxy Server Property Encoding
//
// Sleep Proxy Servers are advertised using a structured service name, consisting of four
// metrics followed by a human-readable name. The metrics assist clients in deciding which
// Sleep Proxy Server(s) to use when multiple are available on the network. Each metric
// is a two-digit decimal number in the range 10-99. Lower metrics are generally better.
//
//   AA-BB-CC-DD Name
//
// Metrics:
//
// AA = Intent
// BB = Portability
// CC = Marginal Power
// DD = Total Power
//
//
// ** Intent Metric **
//
// 20 = Dedicated Sleep Proxy Server -- a device, permanently powered on,
//      installed for the express purpose of providing Sleep Proxy Service.
//
// 30 = Primary Network Infrastructure Hardware -- a router, DHCP server, NAT gateway,
//      or similar permanently installed device which is permanently powered on.
//      This is hardware designed for the express purpose of being network
//      infrastructure, and for most home users is typically a single point
//      of failure for the local network -- e.g. most home users only have
//      a single NAT gateway / DHCP server. Even though in principle the
//      hardware might technically be capable of running different software,
//      a typical user is unlikely to do that. e.g. AirPort base station.
//
// 40 = Primary Network Infrastructure Software -- a general-purpose computer
//      (e.g. Mac, Windows, Linux, etc.) which is currently running DHCP server
//      or NAT gateway software, but the user could choose to turn that off
//      fairly easily. e.g. iMac running Internet Sharing
//
// 50 = Secondary Network Infrastructure Hardware -- like primary infrastructure
//      hardware, except not a single point of failure for the entire local network.
//      For example, an AirPort base station in bridge mode. This may have clients
//      associated with it, and if it goes away those clients will be inconvenienced,
//      but unlike the NAT gateway / DHCP server, the entire local network is not
//      dependent on it.
//
// 60 = Secondary Network Infrastructure Software -- like 50, but in a general-
//      purpose CPU.
//
// 70 = Incidentally Available Hardware -- a device which has no power switch
//      and is generally left powered on all the time. Even though it is not a
//      part of what we conventionally consider network infrastructure (router,
//      DHCP, NAT, DNS, etc.), and the rest of the network can operate fine
//      without it, since it's available and unlikely to be turned off, it is a
//      reasonable candidate for providing Sleep Proxy Service e.g. Apple TV,
//      or an AirPort base station in client mode, associated with an existing
//      wireless network (e.g. AirPort Express connected to a music system, or
//      being used to share a USB printer).
//
// 80 = Incidentally Available Software -- a general-purpose computer which
//      happens at this time to be set to "never sleep", and as such could be
//      useful as a Sleep Proxy Server, but has not been intentionally provided
//      for this purpose. Of all the Intent Metric categories this is the
//      one most likely to be shut down or put to sleep without warning.
//      However, if nothing else is availalable, it may be better than nothing.
//      e.g. Office computer in the workplace which has been set to "never sleep"
//
//
// ** Portability Metric **
//
// Inversely related to mass of device, on the basis that, all other things
// being equal, heavier devices are less likely to be moved than lighter devices.
// E.g. A MacBook running Internet Sharing is probably more likely to be
// put to sleep and taken away than a Mac Pro running Internet Sharing.
// The Portability Metric is a logarithmic decibel scale, computed by taking the
// (approximate) mass of the device in milligrammes, taking the base 10 logarithm
// of that, multiplying by 10, and subtracting the result from 100:
//
//   Portability Metric = 100 - (log10(mg) * 10)
//
// The Portability Metric is not necessarily computed literally from the actual
// mass of the device; the intent is just that lower numbers indicate more
// permanent devices, and higher numbers indicate devices more likely to be
// removed from the network, e.g., in order of increasing portability:
//
// Mac Pro < iMac < Laptop < iPhone
//
// Example values:
//
// 10 = 1 metric tonne
// 40 = 1kg
// 70 = 1g
// 90 = 10mg
//
//
// ** Marginal Power and Total Power Metrics **
//
// The Marginal Power Metric is the power difference between sleeping and staying awake
// to be a Sleep Proxy Server.
//
// The Total Power Metric is the total power consumption when being Sleep Proxy Server.
//
// The Power Metrics use a logarithmic decibel scale, computed as ten times the
// base 10 logarithm of the (approximate) power in microwatts:
//
//   Power Metric = log10(uW) * 10
//
// Higher values indicate higher power consumption. Example values:
//
// 10 =  10 uW
// 20 = 100 uW
// 30 =   1 mW
// 60 =   1 W
// 90 =   1 kW

typedef enum
	{
	mDNSSleepProxyMetric_Dedicated          = 20,
	mDNSSleepProxyMetric_PrimaryHardware    = 30,
	mDNSSleepProxyMetric_PrimarySoftware    = 40,
	mDNSSleepProxyMetric_SecondaryHardware  = 50,
	mDNSSleepProxyMetric_SecondarySoftware  = 60,
	mDNSSleepProxyMetric_IncidentalHardware = 70,
	mDNSSleepProxyMetric_IncidentalSoftware = 80
	} mDNSSleepProxyMetric;

extern void mDNSCoreBeSleepProxyServer_internal(mDNS *const m, mDNSu8 sps, mDNSu8 port, mDNSu8 marginalpower, mDNSu8 totpower);
#define mDNSCoreBeSleepProxyServer(M,S,P,MP,TP) \
	do { mDNS_Lock(m); mDNSCoreBeSleepProxyServer_internal((M),(S),(P),(MP),(TP)); mDNS_Unlock(m); } while(0)

extern void FindSPSInCache(mDNS *const m, const DNSQuestion *const q, const CacheRecord *sps[3]);
#define PrototypeSPSName(X) ((X)[0] >= 11 && (X)[3] == '-' && (X)[ 4] == '9' && (X)[ 5] == '9' && \
                                             (X)[6] == '-' && (X)[ 7] == '9' && (X)[ 8] == '9' && \
                                             (X)[9] == '-' && (X)[10] == '9' && (X)[11] == '9'    )
#define ValidSPSName(X) ((X)[0] >= 5 && mDNSIsDigit((X)[1]) && mDNSIsDigit((X)[2]) && mDNSIsDigit((X)[4]) && mDNSIsDigit((X)[5]))
#define SPSMetric(X) (!ValidSPSName(X) || PrototypeSPSName(X) ? 1000000 : \
	((X)[1]-'0') * 100000 + ((X)[2]-'0') * 10000 + ((X)[4]-'0') * 1000 + ((X)[5]-'0') * 100 + ((X)[7]-'0') * 10 + ((X)[8]-'0'))

// ***************************************************************************
#if 0
#pragma mark -
#pragma mark - Compile-Time assertion checks
#endif

// Some C compiler cleverness. We can make the compiler check certain things for
// us, and report compile-time errors if anything is wrong. The usual way to do
// this would be to use a run-time "if" statement, but then you don't find out
// what's wrong until you run the software. This way, if the assertion condition
// is false, the array size is negative, and the complier complains immediately.

struct CompileTimeAssertionChecks_mDNS
	{
	// Check that the compiler generated our on-the-wire packet format structure definitions
	// properly packed, without adding padding bytes to align fields on 32-bit or 64-bit boundaries.
	char assert0[(sizeof(rdataSRV)         == 262                          ) ? 1 : -1];
	char assert1[(sizeof(DNSMessageHeader) ==  12                          ) ? 1 : -1];
	char assert2[(sizeof(DNSMessage)       ==  12+AbsoluteMaxDNSMessageData) ? 1 : -1];
	char assert3[(sizeof(mDNSs8)           ==   1                          ) ? 1 : -1];
	char assert4[(sizeof(mDNSu8)           ==   1                          ) ? 1 : -1];
	char assert5[(sizeof(mDNSs16)          ==   2                          ) ? 1 : -1];
	char assert6[(sizeof(mDNSu16)          ==   2                          ) ? 1 : -1];
	char assert7[(sizeof(mDNSs32)          ==   4                          ) ? 1 : -1];
	char assert8[(sizeof(mDNSu32)          ==   4                          ) ? 1 : -1];
	char assert9[(sizeof(mDNSOpaque16)     ==   2                          ) ? 1 : -1];
	char assertA[(sizeof(mDNSOpaque32)     ==   4                          ) ? 1 : -1];
	char assertB[(sizeof(mDNSOpaque128)    ==  16                          ) ? 1 : -1];
	char assertC[(sizeof(CacheRecord  )    ==  sizeof(CacheGroup)          ) ? 1 : -1];
	char assertD[(sizeof(int)              >=  4                           ) ? 1 : -1];
	char assertE[(StandardAuthRDSize       >=  256                         ) ? 1 : -1];
	char assertF[(sizeof(EthernetHeader)   ==   14                         ) ? 1 : -1];
	char assertG[(sizeof(ARP_EthIP     )   ==   28                         ) ? 1 : -1];
	char assertH[(sizeof(IPv4Header    )   ==   20                         ) ? 1 : -1];
	char assertI[(sizeof(IPv6Header    )   ==   40                         ) ? 1 : -1];
	char assertJ[(sizeof(IPv6NDP       )   ==   24                         ) ? 1 : -1];
	char assertK[(sizeof(UDPHeader     )   ==    8                         ) ? 1 : -1];
	char assertL[(sizeof(IKEHeader     )   ==   28                         ) ? 1 : -1];
	char assertM[(sizeof(TCPHeader     )   ==   20                         ) ? 1 : -1];

	// Check our structures are reasonable sizes. Including overly-large buffers, or embedding
	// other overly-large structures instead of having a pointer to them, can inadvertently
	// cause structure sizes (and therefore memory usage) to balloon unreasonably.
	char sizecheck_RDataBody           [(sizeof(RDataBody)            ==   264) ? 1 : -1];
	char sizecheck_ResourceRecord      [(sizeof(ResourceRecord)       <=    64) ? 1 : -1];
	char sizecheck_AuthRecord          [(sizeof(AuthRecord)           <=  1208) ? 1 : -1];
	char sizecheck_CacheRecord         [(sizeof(CacheRecord)          <=   184) ? 1 : -1];
	char sizecheck_CacheGroup          [(sizeof(CacheGroup)           <=   184) ? 1 : -1];
	char sizecheck_DNSQuestion         [(sizeof(DNSQuestion)          <=   786) ? 1 : -1];
	char sizecheck_ZoneData            [(sizeof(ZoneData)             <=  1624) ? 1 : -1];
	char sizecheck_NATTraversalInfo    [(sizeof(NATTraversalInfo)     <=   192) ? 1 : -1];
	char sizecheck_HostnameInfo        [(sizeof(HostnameInfo)         <=  3050) ? 1 : -1];
	char sizecheck_DNSServer           [(sizeof(DNSServer)            <=   320) ? 1 : -1];
	char sizecheck_NetworkInterfaceInfo[(sizeof(NetworkInterfaceInfo) <=  6850) ? 1 : -1];
	char sizecheck_ServiceRecordSet    [(sizeof(ServiceRecordSet)     <=  5500) ? 1 : -1];
	char sizecheck_DomainAuthInfo      [(sizeof(DomainAuthInfo)       <=  7808) ? 1 : -1];
	char sizecheck_ServiceInfoQuery    [(sizeof(ServiceInfoQuery)     <=  3200) ? 1 : -1];
#if APPLE_OSX_mDNSResponder
	char sizecheck_ClientTunnel        [(sizeof(ClientTunnel)         <=  1148) ? 1 : -1];
#endif
	};

// ***************************************************************************

#ifdef __cplusplus
	}
#endif

#endif