xref: /aosp_15_r20/external/mdnsresponder/mDNSPosix/NetMonitor.c (revision 48a54d368dc4fa860885eef7b70b6c53499e7c25)

/* -*- Mode: C; tab-width: 4 -*-
 *
 * Copyright (c) 2002-2004 Apple Computer, Inc. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * Formatting notes:
 * This code follows the "Whitesmiths style" C indentation rules. Plenty of discussion
 * on C indentation can be found on the web, such as <http://www.kafejo.com/komp/1tbs.htm>,
 * but for the sake of brevity here I will say just this: Curly braces are not syntactially
 * part of an "if" statement; they are the beginning and ending markers of a compound statement;
 * therefore common sense dictates that if they are part of a compound statement then they
 * should be indented to the same level as everything else in that compound statement.
 * Indenting curly braces at the same level as the "if" implies that curly braces are
 * part of the "if", which is false. (This is as misleading as people who write "char* x,y;"
 * thinking that variables x and y are both of type "char*" -- and anyone who doesn't
 * understand why variable y is not of type "char*" just proves the point that poor code
 * layout leads people to unfortunate misunderstandings about how the C language really works.)
 */

//*************************************************************************************************************
// Incorporate mDNS.c functionality

// We want to use much of the functionality provided by "mDNS.c",
// except we'll steal the packets that would be sent to normal mDNSCoreReceive() routine
#define mDNSCoreReceive __NOT__mDNSCoreReceive__NOT__
#include "mDNS.c"
#undef mDNSCoreReceive

//*************************************************************************************************************
// Headers

#include <stdio.h>			// For printf()
#include <stdlib.h>			// For malloc()
#include <string.h>			// For strrchr(), strcmp()
#include <time.h>			// For "struct tm" etc.
#include <signal.h>			// For SIGINT, SIGTERM
#if defined(WIN32)
// Both mDNS.c and mDNSWin32.h declare UDPSocket_struct type resulting in a compile-time error, so
// trick the compiler when including mDNSWin32.h
#	define UDPSocket_struct _UDPSocket_struct
#	include <mDNSEmbeddedAPI.h>
#	include <mDNSWin32.h>
#	include <PosixCompat.h>
#	define IFNAMSIZ 256
static HANDLE gStopEvent = INVALID_HANDLE_VALUE;
static BOOL WINAPI ConsoleControlHandler( DWORD inControlEvent ) { SetEvent( gStopEvent ); return TRUE; }
void setlinebuf( FILE * fp ) {}
#else
#	include <netdb.h>			// For gethostbyname()
#	include <sys/socket.h>		// For AF_INET, AF_INET6, etc.
#	include <net/if.h>			// For IF_NAMESIZE
#	include <netinet/in.h>		// For INADDR_NONE
#	include <arpa/inet.h>		// For inet_addr()
#	include "mDNSPosix.h"      // Defines the specific types needed to run mDNS on this platform
#endif
#include "ExampleClientApp.h"

//*************************************************************************************************************
// Types and structures

enum
	{
	// Primitive operations
	OP_probe        = 0,
	OP_goodbye      = 1,

	// These are meta-categories;
	// Query and Answer operations are actually subdivided into two classes:
	// Browse  query/answer and
	// Resolve query/answer
	OP_query        = 2,
	OP_answer       = 3,

	// The "Browse" variants of query/answer
	OP_browsegroup  = 2,
	OP_browseq      = 2,
	OP_browsea      = 3,

	// The "Resolve" variants of query/answer
	OP_resolvegroup = 4,
	OP_resolveq     = 4,
	OP_resolvea     = 5,

	OP_NumTypes = 6
	};

typedef struct ActivityStat_struct ActivityStat;
struct ActivityStat_struct
	{
	ActivityStat *next;
	domainname srvtype;
	int printed;
	int totalops;
	int stat[OP_NumTypes];
	};

typedef struct FilterList_struct FilterList;
struct FilterList_struct
	{
	FilterList *next;
	mDNSAddr FilterAddr;
	};

//*************************************************************************************************************
// Constants

#define kReportTopServices 15
#define kReportTopHosts    15

//*************************************************************************************************************
// Globals

mDNS mDNSStorage;						// mDNS core uses this to store its globals
static mDNS_PlatformSupport PlatformStorage;	// Stores this platform's globals
mDNSexport const char ProgramName[] = "mDNSNetMonitor";

struct timeval tv_start, tv_end, tv_interval;
static int FilterInterface = 0;
static FilterList *Filters;
#define ExactlyOneFilter (Filters && !Filters->next)

static int NumPktQ, NumPktL, NumPktR, NumPktB;	// Query/Legacy/Response/Bad
static int NumProbes, NumGoodbyes, NumQuestions, NumLegacy, NumAnswers, NumAdditionals;

static ActivityStat *stats;

#define OPBanner "Total Ops   Probe   Goodbye  BrowseQ  BrowseA ResolveQ ResolveA"

//*************************************************************************************************************
// Utilities

// Special version of printf that knows how to print IP addresses, DNS-format name strings, etc.
mDNSlocal mDNSu32 mprintf(const char *format, ...) IS_A_PRINTF_STYLE_FUNCTION(1,2);
mDNSlocal mDNSu32 mprintf(const char *format, ...)
	{
	mDNSu32 length;
	unsigned char buffer[512];
	va_list ptr;
	va_start(ptr,format);
	length = mDNS_vsnprintf((char *)buffer, sizeof(buffer), format, ptr);
	va_end(ptr);
	printf("%s", buffer);
	return(length);
	}

//*************************************************************************************************************
// Host Address List
//
// Would benefit from a hash

typedef enum
	{
	HostPkt_Q        = 0,		// Query
	HostPkt_L        = 1,		// Legacy Query
	HostPkt_R        = 2,		// Response
	HostPkt_B        = 3,		// Bad
	HostPkt_NumTypes = 4
	} HostPkt_Type;

typedef struct
	{
	mDNSAddr addr;
	unsigned long pkts[HostPkt_NumTypes];
	unsigned long totalops;
	unsigned long stat[OP_NumTypes];
	domainname hostname;
	domainname revname;
	UTF8str255 HIHardware;
	UTF8str255 HISoftware;
	mDNSu32    NumQueries;
	mDNSs32    LastQuery;
	} HostEntry;

#define HostEntryTotalPackets(H) ((H)->pkts[HostPkt_Q] + (H)->pkts[HostPkt_L] + (H)->pkts[HostPkt_R] + (H)->pkts[HostPkt_B])

typedef struct
	{
	long		num;
	long		max;
	HostEntry	*hosts;
	} HostList;

static HostList IPv4HostList = { 0, 0, 0 };
static HostList IPv6HostList = { 0, 0, 0 };

mDNSlocal HostEntry *FindHost(const mDNSAddr *addr, HostList *list)
	{
	long	i;

	for (i = 0; i < list->num; i++)
		{
		HostEntry *entry = list->hosts + i;
		if (mDNSSameAddress(addr, &entry->addr))
			return entry;
		}

	return NULL;
	}

mDNSlocal HostEntry *AddHost(const mDNSAddr *addr, HostList *list)
	{
	int i;
	HostEntry *entry;
	if (list->num >= list->max)
		{
		long newMax = list->max + 64;
		HostEntry *newHosts = realloc(list->hosts, newMax * sizeof(HostEntry));
		if (newHosts == NULL)
			return NULL;
		list->max = newMax;
		list->hosts = newHosts;
		}

	entry = list->hosts + list->num++;

	entry->addr = *addr;
	for (i=0; i<HostPkt_NumTypes; i++) entry->pkts[i] = 0;
	entry->totalops = 0;
	for (i=0; i<OP_NumTypes;      i++) entry->stat[i] = 0;
	entry->hostname.c[0] = 0;
	entry->revname.c[0] = 0;
	entry->HIHardware.c[0] = 0;
	entry->HISoftware.c[0] = 0;
	entry->NumQueries = 0;

	if (entry->addr.type == mDNSAddrType_IPv4)
		{
		mDNSv4Addr ip = entry->addr.ip.v4;
		char buffer[32];
		// Note: This is reverse order compared to a normal dotted-decimal IP address, so we can't use our customary "%.4a" format code
		mDNS_snprintf(buffer, sizeof(buffer), "%d.%d.%d.%d.in-addr.arpa.", ip.b[3], ip.b[2], ip.b[1], ip.b[0]);
		MakeDomainNameFromDNSNameString(&entry->revname, buffer);
		}

	return(entry);
	}

mDNSlocal HostEntry *GotPacketFromHost(const mDNSAddr *addr, HostPkt_Type t, mDNSOpaque16 id)
	{
	if (ExactlyOneFilter) return(NULL);
	else
		{
		HostList *list = (addr->type == mDNSAddrType_IPv4) ? &IPv4HostList : &IPv6HostList;
		HostEntry *entry = FindHost(addr, list);
		if (!entry) entry = AddHost(addr, list);
		if (!entry) return(NULL);
		// Don't count our own interrogation packets
		if (id.NotAnInteger != 0xFFFF) entry->pkts[t]++;
		return(entry);
		}
	}

mDNSlocal void RecordHostInfo(HostEntry *entry, const ResourceRecord *const pktrr)
	{
	if (!entry->hostname.c[0])
		{
		if (pktrr->rrtype == kDNSType_A || pktrr->rrtype == kDNSType_AAAA)
			{
			// Should really check that the rdata in the address record matches the source address of this packet
			entry->NumQueries = 0;
			AssignDomainName(&entry->hostname, pktrr->name);
			}

		if (pktrr->rrtype == kDNSType_PTR)
			if (SameDomainName(&entry->revname, pktrr->name))
				{
				entry->NumQueries = 0;
				AssignDomainName(&entry->hostname, &pktrr->rdata->u.name);
				}
		}
	else if (pktrr->rrtype == kDNSType_HINFO)
		{
		RDataBody *rd = &pktrr->rdata->u;
		mDNSu8 *rdend = (mDNSu8 *)rd + pktrr->rdlength;
		mDNSu8 *hw = rd->txt.c;
		mDNSu8 *sw = hw + 1 + (mDNSu32)hw[0];
		if (sw + 1 + sw[0] <= rdend)
			{
			AssignDomainName(&entry->hostname, pktrr->name);
			mDNSPlatformMemCopy(entry->HIHardware.c, hw, 1 + (mDNSu32)hw[0]);
			mDNSPlatformMemCopy(entry->HISoftware.c, sw, 1 + (mDNSu32)sw[0]);
			}
		}
	}

mDNSlocal void SendUnicastQuery(mDNS *const m, HostEntry *entry, domainname *name, mDNSu16 rrtype, mDNSInterfaceID InterfaceID)
	{
	const mDNSOpaque16 id = { { 0xFF, 0xFF } };
	DNSMessage query;
	mDNSu8       *qptr        = query.data;
	const mDNSu8 *const limit = query.data + sizeof(query.data);
	const mDNSAddr *target    = &entry->addr;
	InitializeDNSMessage(&query.h, id, QueryFlags);
	qptr = putQuestion(&query, qptr, limit, name, rrtype, kDNSClass_IN);
	entry->LastQuery = m->timenow;
	entry->NumQueries++;

	// Note: When there are multiple mDNSResponder agents running on a single machine
	// (e.g. Apple mDNSResponder plus a SliMP3 server with embedded mDNSResponder)
	// it is possible that unicast queries may not go to the primary system responder.
	// We try the first query using unicast, but if that doesn't work we try again via multicast.
	if (entry->NumQueries > 2)
		{
		target = &AllDNSLinkGroup_v4;
		}
	else
		{
		//mprintf("%#a Q\n", target);
		InterfaceID = mDNSInterface_Any;	// Send query from our unicast reply socket
		}

	mDNSSendDNSMessage(&mDNSStorage, &query, qptr, InterfaceID, mDNSNULL, target, MulticastDNSPort, mDNSNULL, mDNSNULL);
	}

mDNSlocal void AnalyseHost(mDNS *const m, HostEntry *entry, const mDNSInterfaceID InterfaceID)
	{
	// If we've done four queries without answer, give up
	if (entry->NumQueries >= 4) return;

	// If we've done a query in the last second, give the host a chance to reply before trying again
	if (entry->NumQueries && m->timenow - entry->LastQuery < mDNSPlatformOneSecond) return;

	// If we don't know the host name, try to find that first
	if (!entry->hostname.c[0])
		{
		if (entry->revname.c[0])
			{
			SendUnicastQuery(m, entry, &entry->revname, kDNSType_PTR, InterfaceID);
			//mprintf("%##s PTR %d\n", entry->revname.c, entry->NumQueries);
			}
		}
	// If we have the host name but no HINFO, now ask for that
	else if (!entry->HIHardware.c[0])
		{
		SendUnicastQuery(m, entry, &entry->hostname, kDNSType_HINFO, InterfaceID);
		//mprintf("%##s HINFO %d\n", entry->hostname.c, entry->NumQueries);
		}
	}

mDNSlocal int CompareHosts(const void *p1, const void *p2)
	{
	return (int)(HostEntryTotalPackets((HostEntry *)p2) - HostEntryTotalPackets((HostEntry *)p1));
	}

mDNSlocal void ShowSortedHostList(HostList *list, int max)
	{
	HostEntry *e, *end = &list->hosts[(max < list->num) ? max : list->num];
	qsort(list->hosts, list->num, sizeof(HostEntry), CompareHosts);
	if (list->num) mprintf("\n%-25s%s%s\n", "Source Address", OPBanner, "    Pkts    Query   LegacyQ Response");
	for (e = &list->hosts[0]; e < end; e++)
		{
		int len = mprintf("%#-25a", &e->addr);
		if (len > 25) mprintf("\n%25s", "");
		mprintf("%8lu %8lu %8lu %8lu %8lu %8lu %8lu", e->totalops,
			e->stat[OP_probe], e->stat[OP_goodbye],
			e->stat[OP_browseq], e->stat[OP_browsea],
			e->stat[OP_resolveq], e->stat[OP_resolvea]);
		mprintf(" %8lu %8lu %8lu %8lu",
			HostEntryTotalPackets(e), e->pkts[HostPkt_Q], e->pkts[HostPkt_L], e->pkts[HostPkt_R]);
		if (e->pkts[HostPkt_B]) mprintf("Bad: %8lu", e->pkts[HostPkt_B]);
		mprintf("\n");
		if (!e->HISoftware.c[0] && e->NumQueries > 2)
			mDNSPlatformMemCopy(&e->HISoftware, "\x27*** Unknown (Jaguar, Windows, etc.) ***", 0x28);
		if (e->hostname.c[0] || e->HIHardware.c[0] || e->HISoftware.c[0])
			mprintf("%##-45s %#-14s %#s\n", e->hostname.c, e->HIHardware.c, e->HISoftware.c);
		}
	}

//*************************************************************************************************************
// Receive and process packets

mDNSexport mDNSBool ExtractServiceType(const domainname *const fqdn, domainname *const srvtype)
	{
	int i, len;
	const mDNSu8 *src = fqdn->c;
	mDNSu8 *dst = srvtype->c;

	len = *src;
	if (len == 0 || len >= 0x40) return(mDNSfalse);
	if (src[1] != '_') src += 1 + len;

	len = *src;
	if (len == 0 || len >= 0x40 || src[1] != '_') return(mDNSfalse);
	for (i=0; i<=len; i++) *dst++ = *src++;

	len = *src;
	if (len == 0 || len >= 0x40 || src[1] != '_') return(mDNSfalse);
	for (i=0; i<=len; i++) *dst++ = *src++;

	*dst++ = 0;		// Put the null root label on the end of the service type

	return(mDNStrue);
	}

mDNSlocal void recordstat(HostEntry *entry, const domainname *fqdn, int op, mDNSu16 rrtype)
	{
	ActivityStat **s = &stats;
	domainname srvtype;

	if (op != OP_probe)
		{
		if (rrtype == kDNSType_SRV || rrtype == kDNSType_TXT) op = op - OP_browsegroup + OP_resolvegroup;
		else if (rrtype != kDNSType_PTR) return;
		}

	if (!ExtractServiceType(fqdn, &srvtype)) return;

	while (*s && !SameDomainName(&(*s)->srvtype, &srvtype)) s = &(*s)->next;
	if (!*s)
		{
		int i;
		*s = malloc(sizeof(ActivityStat));
		if (!*s) exit(-1);
		(*s)->next     = NULL;
		(*s)->srvtype  = srvtype;
		(*s)->printed  = 0;
		(*s)->totalops = 0;
		for (i=0; i<OP_NumTypes; i++) (*s)->stat[i] = 0;
		}

	(*s)->totalops++;
	(*s)->stat[op]++;
	if (entry)
		{
		entry->totalops++;
		entry->stat[op]++;
		}
	}

mDNSlocal void printstats(int max)
	{
	int i;
	if (!stats) return;
	for (i=0; i<max; i++)
		{
		int max = 0;
		ActivityStat *s, *m = NULL;
		for (s = stats; s; s=s->next)
			if (!s->printed && max < s->totalops)
				{ m = s; max = s->totalops; }
		if (!m) return;
		m->printed = mDNStrue;
		if (i==0) mprintf("%-25s%s\n", "Service Type", OPBanner);
		mprintf("%##-25s%8d %8d %8d %8d %8d %8d %8d\n", m->srvtype.c, m->totalops, m->stat[OP_probe],
			m->stat[OP_goodbye], m->stat[OP_browseq], m->stat[OP_browsea], m->stat[OP_resolveq], m->stat[OP_resolvea]);
		}
	}

mDNSlocal const mDNSu8 *FindUpdate(mDNS *const m, const DNSMessage *const query, const mDNSu8 *ptr, const mDNSu8 *const end,
	DNSQuestion *q, LargeCacheRecord *pkt)
	{
	int i;
	for (i = 0; i < query->h.numAuthorities; i++)
		{
		const mDNSu8 *p2 = ptr;
		ptr = GetLargeResourceRecord(m, query, ptr, end, q->InterfaceID, kDNSRecordTypePacketAuth, pkt);
		if (!ptr) break;
		if (m->rec.r.resrec.RecordType != kDNSRecordTypePacketNegative && ResourceRecordAnswersQuestion(&pkt->r.resrec, q)) return(p2);
		}
	return(mDNSNULL);
	}

mDNSlocal void DisplayPacketHeader(mDNS *const m, const DNSMessage *const msg, const mDNSu8 *const end, const mDNSAddr *srcaddr, mDNSIPPort srcport, const mDNSAddr *dstaddr, const mDNSInterfaceID InterfaceID)
	{
	const char *const ptype =   (msg->h.flags.b[0] & kDNSFlag0_QR_Response)             ? "-R- " :
								(srcport.NotAnInteger == MulticastDNSPort.NotAnInteger) ? "-Q- " : "-LQ-";

	struct timeval tv;
	struct tm tm;
	const mDNSu32 index = mDNSPlatformInterfaceIndexfromInterfaceID(m, InterfaceID, mDNSfalse);
	char if_name[IFNAMSIZ];		// Older Linux distributions don't define IF_NAMESIZE
	if_indextoname(index, if_name);
	gettimeofday(&tv, NULL);
	localtime_r((time_t*)&tv.tv_sec, &tm);
	mprintf("\n%d:%02d:%02d.%06d Interface %d/%s\n", tm.tm_hour, tm.tm_min, tm.tm_sec, tv.tv_usec, index, if_name);

	mprintf("%#-16a %s             Q:%3d  Ans:%3d  Auth:%3d  Add:%3d  Size:%5d bytes",
		srcaddr, ptype, msg->h.numQuestions, msg->h.numAnswers, msg->h.numAuthorities, msg->h.numAdditionals, end - (mDNSu8 *)msg);

	if (msg->h.id.NotAnInteger) mprintf("  ID:%u", mDNSVal16(msg->h.id));

	if (!mDNSAddrIsDNSMulticast(dstaddr)) mprintf("   To: %#a", dstaddr);

	if (msg->h.flags.b[0] & kDNSFlag0_TC)
		{
		if (msg->h.flags.b[0] & kDNSFlag0_QR_Response) mprintf("   Truncated");
		else                                           mprintf("   Truncated (KA list continues in next packet)");
		}
	mprintf("\n");
	}

mDNSlocal void DisplayResourceRecord(const mDNSAddr *const srcaddr, const char *const op, const ResourceRecord *const pktrr)
	{
	static const char hexchars[16] = "0123456789ABCDEF";
	#define MaxWidth 132
	char buffer[MaxWidth+8];
	char *p = buffer;

	RDataBody *rd = &pktrr->rdata->u;
	mDNSu8 *rdend = (mDNSu8 *)rd + pktrr->rdlength;
	int n = mprintf("%#-16a %-5s %-5s%5lu %##s -> ", srcaddr, op, DNSTypeName(pktrr->rrtype), pktrr->rroriginalttl, pktrr->name->c);

	if (pktrr->RecordType == kDNSRecordTypePacketNegative) { mprintf("**** ERROR: FAILED TO READ RDATA ****\n"); return; }

	// The kDNSType_OPT case below just calls GetRRDisplayString_rdb
	// Perhaps more (or all?) of the cases should do that?
	switch(pktrr->rrtype)
		{
		case kDNSType_A:	n += mprintf("%.4a", &rd->ipv4); break;
		case kDNSType_PTR:	n += mprintf("%##.*s", MaxWidth - n, rd->name.c); break;
		case kDNSType_HINFO:// same as kDNSType_TXT below
		case kDNSType_TXT:	{
							mDNSu8 *t = rd->txt.c;
							while (t < rdend && t[0] && p < buffer+MaxWidth)
								{
								int i;
								for (i=1; i<=t[0] && p < buffer+MaxWidth; i++)
									{
									if (t[i] == '\\') *p++ = '\\';
									if (t[i] >= ' ') *p++ = t[i];
									else
										{
										*p++ = '\\';
										*p++ = '0';
										*p++ = 'x';
										*p++ = hexchars[t[i] >> 4];
										*p++ = hexchars[t[i] & 0xF];
										}
									}
								t += 1+t[0];
								if (t < rdend && t[0]) { *p++ = '\\'; *p++ = ' '; }
								}
							*p++ = 0;
							n += mprintf("%.*s", MaxWidth - n, buffer);
							} break;
		case kDNSType_AAAA:	n += mprintf("%.16a", &rd->ipv6); break;
		case kDNSType_SRV:	n += mprintf("%##s:%d", rd->srv.target.c, mDNSVal16(rd->srv.port)); break;
		case kDNSType_OPT:	{
							char b[MaxMsg];
							// Quick hack: we don't want the prefix that GetRRDisplayString_rdb puts at the start of its
							// string, because it duplicates the name and rrtype we already display, so we compute the
							// length of that prefix and strip that many bytes off the beginning of the string we display.
							mDNSu32 striplen = mDNS_snprintf(b, MaxMsg-1, "%4d %##s %s ", pktrr->rdlength, pktrr->name->c, DNSTypeName(pktrr->rrtype));
							GetRRDisplayString_rdb(pktrr, &pktrr->rdata->u, b);
							n += mprintf("%.*s", MaxWidth - n, b + striplen);
							} break;
		case kDNSType_NSEC:	{
							int i;
							for (i=0; i<255; i++)
								if (rd->nsec.bitmap[i>>3] & (128 >> (i&7)))
									n += mprintf("%s ", DNSTypeName(i));
							} break;
		default:			{
							mDNSu8 *s = rd->data;
							while (s < rdend && p < buffer+MaxWidth)
								{
								if (*s == '\\') *p++ = '\\';
								if (*s >= ' ') *p++ = *s;
								else
									{
									*p++ = '\\';
									*p++ = '0';
									*p++ = 'x';
									*p++ = hexchars[*s >> 4];
									*p++ = hexchars[*s & 0xF];
									}
								s++;
								}
							*p++ = 0;
							n += mprintf("%.*s", MaxWidth - n, buffer);
							} break;
		}

	mprintf("\n");
	}

mDNSlocal void HexDump(const mDNSu8 *ptr, const mDNSu8 *const end)
	{
	while (ptr < end)
		{
		int i;
		for (i=0; i<16; i++)
			if (&ptr[i] < end) mprintf("%02X ", ptr[i]);
			else mprintf("   ");
		for (i=0; i<16; i++)
			if (&ptr[i] < end) mprintf("%c", ptr[i] <= ' ' || ptr[i] >= 126 ? '.' : ptr[i]);
		ptr += 16;
		mprintf("\n");
		}
	}

mDNSlocal void DisplayError(const mDNSAddr *srcaddr, const mDNSu8 *ptr, const mDNSu8 *const end, char *msg)
	{
	mprintf("%#-16a **** ERROR: FAILED TO READ %s **** \n", srcaddr, msg);
	HexDump(ptr, end);
	}

mDNSlocal void DisplayQuery(mDNS *const m, const DNSMessage *const msg, const mDNSu8 *const end,
	const mDNSAddr *srcaddr, mDNSIPPort srcport, const mDNSAddr *dstaddr, const mDNSInterfaceID InterfaceID)
	{
	int i;
	const mDNSu8 *ptr = msg->data;
	const mDNSu8 *auth = LocateAuthorities(msg, end);
	mDNSBool MQ = (srcport.NotAnInteger == MulticastDNSPort.NotAnInteger);
	HostEntry *entry = GotPacketFromHost(srcaddr, MQ ? HostPkt_Q : HostPkt_L, msg->h.id);
	LargeCacheRecord pkt;

	DisplayPacketHeader(m, msg, end, srcaddr, srcport, dstaddr, InterfaceID);
	if (msg->h.id.NotAnInteger != 0xFFFF)
		{
		if (MQ) NumPktQ++; else NumPktL++;
		}

	for (i=0; i<msg->h.numQuestions; i++)
		{
		DNSQuestion q;
		mDNSu8 *p2 = (mDNSu8 *)getQuestion(msg, ptr, end, InterfaceID, &q);
		mDNSu16 ucbit = q.qclass & kDNSQClass_UnicastResponse;
		q.qclass &= ~kDNSQClass_UnicastResponse;
		if (!p2) { DisplayError(srcaddr, ptr, end, "QUESTION"); return; }
		ptr = p2;
		p2 = (mDNSu8 *)FindUpdate(m, msg, auth, end, &q, &pkt);
		if (p2)
			{
			NumProbes++;
			DisplayResourceRecord(srcaddr, ucbit ? "(PU)" : "(PM)", &pkt.r.resrec);
			recordstat(entry, &q.qname, OP_probe, q.qtype);
			p2 = (mDNSu8 *)skipDomainName(msg, p2, end);
			// Having displayed this update record, clear type and class so we don't display the same one again.
			p2[0] = p2[1] = p2[2] = p2[3] = 0;
			}
		else
			{
			const char *ptype = ucbit ? "(QU)" : "(QM)";
			if (srcport.NotAnInteger == MulticastDNSPort.NotAnInteger) NumQuestions++;
			else { NumLegacy++; ptype = "(LQ)"; }
			mprintf("%#-16a %-5s %-5s      %##s\n", srcaddr, ptype, DNSTypeName(q.qtype), q.qname.c);
			if (msg->h.id.NotAnInteger != 0xFFFF) recordstat(entry, &q.qname, OP_query, q.qtype);
			}
		}

	for (i=0; i<msg->h.numAnswers; i++)
		{
		const mDNSu8 *ep = ptr;
		ptr = GetLargeResourceRecord(m, msg, ptr, end, InterfaceID, kDNSRecordTypePacketAns, &pkt);
		if (!ptr) { DisplayError(srcaddr, ep, end, "KNOWN ANSWER"); return; }
		DisplayResourceRecord(srcaddr, "(KA)", &pkt.r.resrec);

		// In the case of queries with long multi-packet KA lists, we count each subsequent KA packet
		// the same as a single query, to more accurately reflect the burden on the network
		// (A query with a six-packet KA list is *at least* six times the burden on the network as a single-packet query.)
		if (msg->h.numQuestions == 0 && i == 0)
			recordstat(entry, pkt.r.resrec.name, OP_query, pkt.r.resrec.rrtype);
		}

	for (i=0; i<msg->h.numAuthorities; i++)
		{
		const mDNSu8 *ep = ptr;
		ptr = GetLargeResourceRecord(m, msg, ptr, end, InterfaceID, kDNSRecordTypePacketAuth, &pkt);
		if (!ptr) { DisplayError(srcaddr, ep, end, "AUTHORITY"); return; }
		// After we display an Update record with its matching question (above) we zero out its type and class
		// If any remain that haven't been zero'd out, display them here
		if (pkt.r.resrec.rrtype || pkt.r.resrec.rrclass) DisplayResourceRecord(srcaddr, "(AU)", &pkt.r.resrec);
		}

	for (i=0; i<msg->h.numAdditionals; i++)
		{
		const mDNSu8 *ep = ptr;
		ptr = GetLargeResourceRecord(m, msg, ptr, end, InterfaceID, kDNSRecordTypePacketAdd, &pkt);
		if (!ptr) { DisplayError(srcaddr, ep, end, "ADDITIONAL"); return; }
		DisplayResourceRecord(srcaddr, pkt.r.resrec.rrtype == kDNSType_OPT ? "(OP)" : "(AD)", &pkt.r.resrec);
		}

	if (entry) AnalyseHost(m, entry, InterfaceID);
	}

mDNSlocal void DisplayResponse(mDNS *const m, const DNSMessage *const msg, const mDNSu8 *end,
	const mDNSAddr *srcaddr, mDNSIPPort srcport, const mDNSAddr *dstaddr, const mDNSInterfaceID InterfaceID)
	{
	int i;
	const mDNSu8 *ptr = msg->data;
	HostEntry *entry = GotPacketFromHost(srcaddr, HostPkt_R, msg->h.id);
	LargeCacheRecord pkt;

	DisplayPacketHeader(m, msg, end, srcaddr, srcport, dstaddr, InterfaceID);
	if (msg->h.id.NotAnInteger != 0xFFFF) NumPktR++;

	for (i=0; i<msg->h.numQuestions; i++)
		{
		DNSQuestion q;
		const mDNSu8 *ep = ptr;
		ptr = getQuestion(msg, ptr, end, InterfaceID, &q);
		if (!ptr) { DisplayError(srcaddr, ep, end, "QUESTION"); return; }
		if (mDNSAddrIsDNSMulticast(dstaddr))
			mprintf("%#-16a (?)   **** ERROR: SHOULD NOT HAVE Q IN mDNS RESPONSE **** %-5s %##s\n", srcaddr, DNSTypeName(q.qtype), q.qname.c);
		else
			mprintf("%#-16a (Q)   %-5s      %##s\n", srcaddr, DNSTypeName(q.qtype), q.qname.c);
		}

	for (i=0; i<msg->h.numAnswers; i++)
		{
		const mDNSu8 *ep = ptr;
		ptr = GetLargeResourceRecord(m, msg, ptr, end, InterfaceID, kDNSRecordTypePacketAns, &pkt);
		if (!ptr) { DisplayError(srcaddr, ep, end, "ANSWER"); return; }
		if (pkt.r.resrec.rroriginalttl)
			{
			NumAnswers++;
			DisplayResourceRecord(srcaddr, (pkt.r.resrec.RecordType & kDNSRecordTypePacketUniqueMask) ? "(AN)" : "(AN+)", &pkt.r.resrec);
			if (msg->h.id.NotAnInteger != 0xFFFF) recordstat(entry, pkt.r.resrec.name, OP_answer, pkt.r.resrec.rrtype);
			if (entry) RecordHostInfo(entry, &pkt.r.resrec);
			}
		else
			{
			NumGoodbyes++;
			DisplayResourceRecord(srcaddr, "(DE)", &pkt.r.resrec);
			recordstat(entry, pkt.r.resrec.name, OP_goodbye, pkt.r.resrec.rrtype);
			}
		}

	for (i=0; i<msg->h.numAuthorities; i++)
		{
		const mDNSu8 *ep = ptr;
		ptr = GetLargeResourceRecord(m, msg, ptr, end, InterfaceID, kDNSRecordTypePacketAuth, &pkt);
		if (!ptr) { DisplayError(srcaddr, ep, end, "AUTHORITY"); return; }
		mprintf("%#-16a (?)  **** ERROR: SHOULD NOT HAVE AUTHORITY IN mDNS RESPONSE **** %-5s %##s\n",
			srcaddr, DNSTypeName(pkt.r.resrec.rrtype), pkt.r.resrec.name->c);
		}

	for (i=0; i<msg->h.numAdditionals; i++)
		{
		const mDNSu8 *ep = ptr;
		ptr = GetLargeResourceRecord(m, msg, ptr, end, InterfaceID, kDNSRecordTypePacketAdd, &pkt);
		if (!ptr) { DisplayError(srcaddr, ep, end, "ADDITIONAL"); return; }
		NumAdditionals++;
		DisplayResourceRecord(srcaddr,
			pkt.r.resrec.rrtype == kDNSType_OPT ? "(OP)" : (pkt.r.resrec.RecordType & kDNSRecordTypePacketUniqueMask) ? "(AD)" : "(AD+)",
			&pkt.r.resrec);
		if (entry) RecordHostInfo(entry, &pkt.r.resrec);
		}

	if (entry) AnalyseHost(m, entry, InterfaceID);
	}

mDNSlocal void ProcessUnicastResponse(mDNS *const m, const DNSMessage *const msg, const mDNSu8 *end, const mDNSAddr *srcaddr, const mDNSInterfaceID InterfaceID)
	{
	int i;
	const mDNSu8 *ptr = LocateAnswers(msg, end);
	HostEntry *entry = GotPacketFromHost(srcaddr, HostPkt_R, msg->h.id);
	//mprintf("%#a R\n", srcaddr);

	for (i=0; i<msg->h.numAnswers + msg->h.numAuthorities + msg->h.numAdditionals; i++)
		{
		LargeCacheRecord pkt;
		ptr = GetLargeResourceRecord(m, msg, ptr, end, InterfaceID, kDNSRecordTypePacketAns, &pkt);
		if (ptr && pkt.r.resrec.rroriginalttl && entry) RecordHostInfo(entry, &pkt.r.resrec);
		}
	}

mDNSlocal mDNSBool AddressMatchesFilterList(const mDNSAddr *srcaddr)
	{
	FilterList *f;
	if (!Filters) return(srcaddr->type == mDNSAddrType_IPv4);
	for (f=Filters; f; f=f->next) if (mDNSSameAddress(srcaddr, &f->FilterAddr)) return(mDNStrue);
	return(mDNSfalse);
	}

mDNSexport void mDNSCoreReceive(mDNS *const m, DNSMessage *const msg, const mDNSu8 *const end,
	const mDNSAddr *srcaddr, mDNSIPPort srcport, const mDNSAddr *dstaddr, mDNSIPPort dstport, const mDNSInterfaceID InterfaceID)
	{
	const mDNSu8 StdQ = kDNSFlag0_QR_Query    | kDNSFlag0_OP_StdQuery;
	const mDNSu8 StdR = kDNSFlag0_QR_Response | kDNSFlag0_OP_StdQuery;
	const mDNSu8 QR_OP = (mDNSu8)(msg->h.flags.b[0] & kDNSFlag0_QROP_Mask);
	mDNSu8 *ptr = (mDNSu8 *)&msg->h.numQuestions;
	int goodinterface = (FilterInterface == 0);

	(void)dstaddr;	// Unused
	(void)dstport;	// Unused

	// Read the integer parts which are in IETF byte-order (MSB first, LSB second)
	msg->h.numQuestions   = (mDNSu16)((mDNSu16)ptr[0] <<  8 | ptr[1]);
	msg->h.numAnswers     = (mDNSu16)((mDNSu16)ptr[2] <<  8 | ptr[3]);
	msg->h.numAuthorities = (mDNSu16)((mDNSu16)ptr[4] <<  8 | ptr[5]);
	msg->h.numAdditionals = (mDNSu16)((mDNSu16)ptr[6] <<  8 | ptr[7]);

	// For now we're only interested in monitoring IPv4 traffic.
	// All IPv6 packets should just be duplicates of the v4 packets.
	if (!goodinterface) goodinterface = (FilterInterface == (int)mDNSPlatformInterfaceIndexfromInterfaceID(m, InterfaceID, mDNSfalse));
	if (goodinterface && AddressMatchesFilterList(srcaddr))
		{
		mDNS_Lock(m);
		if (!mDNSAddrIsDNSMulticast(dstaddr))
			{
			if      (QR_OP == StdQ) mprintf("Unicast query from %#a\n", srcaddr);
			else if (QR_OP == StdR) ProcessUnicastResponse(m, msg, end, srcaddr,                   InterfaceID);
			}
		else
			{
			if      (QR_OP == StdQ) DisplayQuery          (m, msg, end, srcaddr, srcport, dstaddr, InterfaceID);
			else if (QR_OP == StdR) DisplayResponse       (m, msg, end, srcaddr, srcport, dstaddr, InterfaceID);
			else
				{
				debugf("Unknown DNS packet type %02X%02X (ignored)", msg->h.flags.b[0], msg->h.flags.b[1]);
				GotPacketFromHost(srcaddr, HostPkt_B, msg->h.id);
				NumPktB++;
				}
			}
		mDNS_Unlock(m);
		}
	}

mDNSlocal mStatus mDNSNetMonitor(void)
	{
	struct tm tm;
	int h, m, s, mul, div, TotPkt;
#if !defined(WIN32)
	sigset_t signals;
#endif

	mStatus status = mDNS_Init(&mDNSStorage, &PlatformStorage,
		mDNS_Init_NoCache, mDNS_Init_ZeroCacheSize,
		mDNS_Init_DontAdvertiseLocalAddresses,
		mDNS_Init_NoInitCallback, mDNS_Init_NoInitCallbackContext);
	if (status) return(status);

	gettimeofday(&tv_start, NULL);

#if defined( WIN32 )
	status = SetupInterfaceList(&mDNSStorage);
	if (status) return(status);
	gStopEvent = CreateEvent(NULL, FALSE, FALSE, NULL);
	if (gStopEvent == INVALID_HANDLE_VALUE) return mStatus_UnknownErr;
	if (!SetConsoleCtrlHandler(ConsoleControlHandler, TRUE)) return mStatus_UnknownErr;
	while (WaitForSingleObjectEx(gStopEvent, INFINITE, TRUE) == WAIT_IO_COMPLETION)
		DispatchSocketEvents(&mDNSStorage);
	if (!SetConsoleCtrlHandler(ConsoleControlHandler, FALSE)) return mStatus_UnknownErr;
	CloseHandle(gStopEvent);
#else
	mDNSPosixListenForSignalInEventLoop(SIGINT);
	mDNSPosixListenForSignalInEventLoop(SIGTERM);

	do
		{
		struct timeval	timeout = { 0x3FFFFFFF, 0 };	// wait until SIGINT or SIGTERM
		mDNSBool		gotSomething;
		mDNSPosixRunEventLoopOnce(&mDNSStorage, &timeout, &signals, &gotSomething);
		}
	while ( !( sigismember( &signals, SIGINT) || sigismember( &signals, SIGTERM)));
#endif

	// Now display final summary
	TotPkt = NumPktQ + NumPktL + NumPktR;
	gettimeofday(&tv_end, NULL);
	tv_interval = tv_end;
	if (tv_start.tv_usec > tv_interval.tv_usec)
		{ tv_interval.tv_usec += 1000000; tv_interval.tv_sec--; }
	tv_interval.tv_sec  -= tv_start.tv_sec;
	tv_interval.tv_usec -= tv_start.tv_usec;
	h = (tv_interval.tv_sec / 3600);
	m = (tv_interval.tv_sec % 3600) / 60;
	s = (tv_interval.tv_sec % 60);
	if (tv_interval.tv_sec > 10)
		{
		mul = 60;
		div = tv_interval.tv_sec;
		}
	else
		{
		mul = 60000;
		div = tv_interval.tv_sec * 1000 + tv_interval.tv_usec / 1000;
		if (div == 0) div=1;
		}

	mprintf("\n\n");
	localtime_r((time_t*)&tv_start.tv_sec, &tm);
	mprintf("Started      %3d:%02d:%02d.%06d\n", tm.tm_hour, tm.tm_min, tm.tm_sec, tv_start.tv_usec);
	localtime_r((time_t*)&tv_end.tv_sec, &tm);
	mprintf("End          %3d:%02d:%02d.%06d\n", tm.tm_hour, tm.tm_min, tm.tm_sec, tv_end.tv_usec);
	mprintf("Captured for %3d:%02d:%02d.%06d\n", h, m, s, tv_interval.tv_usec);
	if (!Filters)
		{
		mprintf("Unique source addresses seen on network:");
		if (IPv4HostList.num) mprintf(" %ld (IPv4)", IPv4HostList.num);
		if (IPv6HostList.num) mprintf(" %ld (IPv6)", IPv6HostList.num);
		if (!IPv4HostList.num && !IPv6HostList.num) mprintf(" None");
		mprintf("\n");
		}
	mprintf("\n");
	mprintf("Modern Query        Packets:      %7d   (avg%5d/min)\n", NumPktQ,        NumPktQ        * mul / div);
	mprintf("Legacy Query        Packets:      %7d   (avg%5d/min)\n", NumPktL,        NumPktL        * mul / div);
	mprintf("Multicast Response  Packets:      %7d   (avg%5d/min)\n", NumPktR,        NumPktR        * mul / div);
	mprintf("Total     Multicast Packets:      %7d   (avg%5d/min)\n", TotPkt,         TotPkt         * mul / div);
	mprintf("\n");
	mprintf("Total New Service Probes:         %7d   (avg%5d/min)\n", NumProbes,      NumProbes      * mul / div);
	mprintf("Total Goodbye Announcements:      %7d   (avg%5d/min)\n", NumGoodbyes,    NumGoodbyes    * mul / div);
	mprintf("Total Query Questions:            %7d   (avg%5d/min)\n", NumQuestions,   NumQuestions   * mul / div);
	mprintf("Total Queries from Legacy Clients:%7d   (avg%5d/min)\n", NumLegacy,      NumLegacy      * mul / div);
	mprintf("Total Answers/Announcements:      %7d   (avg%5d/min)\n", NumAnswers,     NumAnswers     * mul / div);
	mprintf("Total Additional Records:         %7d   (avg%5d/min)\n", NumAdditionals, NumAdditionals * mul / div);
	mprintf("\n");
	printstats(kReportTopServices);

	if (!ExactlyOneFilter)
		{
		ShowSortedHostList(&IPv4HostList, kReportTopHosts);
		ShowSortedHostList(&IPv6HostList, kReportTopHosts);
		}

	mDNS_Close(&mDNSStorage);
	return(0);
	}

mDNSexport int main(int argc, char **argv)
	{
	const char *progname = strrchr(argv[0], '/') ? strrchr(argv[0], '/') + 1 : argv[0];
	int i;
	mStatus status;

#if defined(WIN32)
	HeapSetInformation(NULL, HeapEnableTerminationOnCorruption, NULL, 0);
#endif

	setlinebuf(stdout);				// Want to see lines as they appear, not block buffered

	for (i=1; i<argc; i++)
		{
		if (i+1 < argc && !strcmp(argv[i], "-i") && atoi(argv[i+1]))
			{
			FilterInterface = atoi(argv[i+1]);
			i += 2;
			printf("Monitoring interface %d\n", FilterInterface);
			}
		else
			{
			struct in_addr s4;
			struct in6_addr s6;
			FilterList *f;
			mDNSAddr a;
			a.type = mDNSAddrType_IPv4;

			if (inet_pton(AF_INET, argv[i], &s4) == 1)
				a.ip.v4.NotAnInteger = s4.s_addr;
			else if (inet_pton(AF_INET6, argv[i], &s6) == 1)
				{
				a.type = mDNSAddrType_IPv6;
				mDNSPlatformMemCopy(&a.ip.v6, &s6, sizeof(a.ip.v6));
				}
			else
				{
				struct hostent *h = gethostbyname(argv[i]);
				if (h) a.ip.v4.NotAnInteger = *(long*)h->h_addr;
				else goto usage;
				}

			f = malloc(sizeof(*f));
			f->FilterAddr = a;
			f->next = Filters;
			Filters = f;
			}
		}

	status = mDNSNetMonitor();
	if (status) { fprintf(stderr, "%s: mDNSNetMonitor failed %d\n", progname, (int)status); return(status); }
	return(0);

usage:
	fprintf(stderr, "\nmDNS traffic monitor\n");
	fprintf(stderr, "Usage: %s [-i index] [host]\n", progname);
	fprintf(stderr, "Optional [-i index] parameter displays only packets from that interface index\n");
	fprintf(stderr, "Optional [host] parameter displays only packets from that host\n");

	fprintf(stderr, "\nPer-packet header output:\n");
	fprintf(stderr, "-Q-            Multicast Query from mDNS client that accepts multicast responses\n");
	fprintf(stderr, "-R-            Multicast Response packet containing answers/announcements\n");
	fprintf(stderr, "-LQ-           Multicast Query from legacy client that does *not* listen for multicast responses\n");
	fprintf(stderr, "Q/Ans/Auth/Add Number of questions, answers, authority records and additional records in packet\n");

	fprintf(stderr, "\nPer-record display:\n");
	fprintf(stderr, "(PM)           Probe Question (new service starting), requesting multicast response\n");
	fprintf(stderr, "(PU)           Probe Question (new service starting), requesting unicast response\n");
	fprintf(stderr, "(DE)           Deletion/Goodbye (service going away)\n");
	fprintf(stderr, "(LQ)           Legacy Query Question\n");
	fprintf(stderr, "(QM)           Query Question, requesting multicast response\n");
	fprintf(stderr, "(QU)           Query Question, requesting unicast response\n");
	fprintf(stderr, "(KA)           Known Answer (information querier already knows)\n");
	fprintf(stderr, "(AN)           Unique Answer to question (or periodic announcment) (entire RR Set)\n");
	fprintf(stderr, "(AN+)          Answer to question (or periodic announcment) (add to existing RR Set members)\n");
	fprintf(stderr, "(AD)           Unique Additional Record Set (entire RR Set)\n");
	fprintf(stderr, "(AD+)          Additional records (add to existing RR Set members)\n");

	fprintf(stderr, "\nFinal summary, sorted by service type:\n");
	fprintf(stderr, "Probe          Probes for this service type starting up\n");
	fprintf(stderr, "Goodbye        Goodbye (deletion) packets for this service type shutting down\n");
	fprintf(stderr, "BrowseQ        Browse questions from clients browsing to find a list of instances of this service\n");
	fprintf(stderr, "BrowseA        Browse answers/announcments advertising instances of this service\n");
	fprintf(stderr, "ResolveQ       Resolve questions from clients actively connecting to an instance of this service\n");
	fprintf(stderr, "ResolveA       Resolve answers/announcments giving connection information for an instance of this service\n");
	fprintf(stderr, "\n");
	return(-1);
	}