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/* -*- 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
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* 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 <>,
* 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 the functionality provided by "mDNS.c",
// except we'll sneak a peek at the packets before forwarding them to the normal mDNSCoreReceive() routine
#define mDNSCoreReceive __MDNS__mDNSCoreReceive
#include "mDNS.c"
#undef mDNSCoreReceive
// Headers
#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netinet/in_systm.h> // For n_long, required by <netinet/ip.h> below
#include <netinet/ip.h> // For IPTOS_LOWDELAY etc.
#include <arpa/inet.h>
#include <signal.h>
#include "mDNSEmbeddedAPI.h"// Defines the interface to the mDNS core code
#include "mDNSPosix.h" // Defines the specific types needed to run mDNS on this platform
#include "ExampleClientApp.h"
// Globals
static mDNS mDNSStorage; // mDNS core uses this to store its globals
static mDNS_PlatformSupport PlatformStorage; // Stores this platform's globals
#define RR_CACHE_SIZE 500
static CacheEntity gRRCache[RR_CACHE_SIZE];
mDNSexport const char ProgramName[] = "mDNSIdentify";
static volatile int StopNow; // 0 means running, 1 means stop because we got an answer, 2 means stop because of Ctrl-C
static volatile int NumAnswers, NumAddr, NumAAAA, NumHINFO;
static char hostname[MAX_ESCAPED_DOMAIN_NAME], hardware[256], software[256];
static mDNSAddr lastsrc, hostaddr, target;
static mDNSOpaque16 lastid, id;
// 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;
length = mDNS_vsnprintf((char *)buffer, sizeof(buffer), format, ptr);
printf("%s", buffer);
// Main code
mDNSexport void mDNSCoreReceive(mDNS *const m, DNSMessage *const msg, const mDNSu8 *const end,
const mDNSAddr *const srcaddr, const mDNSIPPort srcport, const mDNSAddr *const dstaddr, const mDNSIPPort dstport,
const mDNSInterfaceID InterfaceID)
(void)dstaddr; // Unused
// Snag copy of header ID, then call through
lastid = msg->;
lastsrc = *srcaddr;
// We *want* to allow off-net unicast responses here.
// For now, the simplest way to allow that is to pretend it was received via multicast so that mDNSCore doesn't reject the packet
__MDNS__mDNSCoreReceive(m, msg, end, srcaddr, srcport, &AllDNSLinkGroup_v4, dstport, InterfaceID);
mDNSlocal void NameCallback(mDNS *const m, DNSQuestion *question, const ResourceRecord *const answer, QC_result AddRecord)
(void)m; // Unused
(void)question; // Unused
(void)AddRecord;// Unused
if (!id.NotAnInteger) id = lastid;
if (answer->rrtype == kDNSType_PTR || answer->rrtype == kDNSType_CNAME)
ConvertDomainNameToCString(&answer->rdata->, hostname);
StopNow = 1;
mprintf("%##s %s %##s\n", answer->name->c, DNSTypeName(answer->rrtype), answer->rdata->;
mDNSlocal void InfoCallback(mDNS *const m, DNSQuestion *question, const ResourceRecord *const answer, QC_result AddRecord)
(void)m; // Unused
(void)question; // Unused
(void)AddRecord;// Unused
if (answer->rrtype == kDNSType_A)
if (!id.NotAnInteger) id = lastid;
mprintf("%##s %s %.4a\n", answer->name->c, DNSTypeName(answer->rrtype), &answer->rdata->u.ipv4);
hostaddr.type = mDNSAddrType_IPv4; // Prefer v4 target to v6 target, for now
hostaddr.ip.v4 = answer->rdata->u.ipv4;
else if (answer->rrtype == kDNSType_AAAA)
if (!id.NotAnInteger) id = lastid;
mprintf("%##s %s %.16a\n", answer->name->c, DNSTypeName(answer->rrtype), &answer->rdata->u.ipv6);
if (!hostaddr.type) // Prefer v4 target to v6 target, for now
hostaddr.type = mDNSAddrType_IPv6;
hostaddr.ip.v6 = answer->rdata->u.ipv6;
else if (answer->rrtype == kDNSType_HINFO)
mDNSu8 *p = answer->rdata->;
strncpy(hardware, (char*)(p+1), p[0]);
hardware[p[0]] = 0;
p += 1 + p[0];
strncpy(software, (char*)(p+1), p[0]);
software[p[0]] = 0;
// If we've got everything we're looking for, don't need to wait any more
if (/*NumHINFO && */ (NumAddr || NumAAAA)) StopNow = 1;
mDNSlocal void ServicesCallback(mDNS *const m, DNSQuestion *question, const ResourceRecord *const answer, QC_result AddRecord)
(void)m; // Unused
(void)question; // Unused
(void)AddRecord;// Unused
// Right now the mDNSCore targeted-query code is incomplete --
// it issues targeted queries, but accepts answers from anywhere
// For now, we'll just filter responses here so we don't get confused by responses from someone else
if (answer->rrtype == kDNSType_PTR && mDNSSameAddress(&lastsrc, &target))
mprintf("%##s %s %##s\n", answer->name->c, DNSTypeName(answer->rrtype), answer->rdata->;
mDNSlocal void WaitForAnswer(mDNS *const m, int seconds)
struct timeval end;
gettimeofday(&end, NULL);
end.tv_sec += seconds;
StopNow = 0;
NumAnswers = 0;
while (!StopNow)
int nfds = 0;
fd_set readfds;
struct timeval now, remain = end;
int result;
gettimeofday(&now, NULL);
if (remain.tv_usec < now.tv_usec) { remain.tv_usec += 1000000; remain.tv_sec--; }
if (remain.tv_sec < now.tv_sec)
if (!NumAnswers) printf("No response after %d seconds\n", seconds);
remain.tv_usec -= now.tv_usec;
remain.tv_sec -= now.tv_sec;
mDNSPosixGetFDSet(m, &nfds, &readfds, &remain);
result = select(nfds, &readfds, NULL, NULL, &remain);
if (result >= 0) mDNSPosixProcessFDSet(m, &readfds);
else if (errno != EINTR) StopNow = 2;
mDNSlocal mStatus StartQuery(DNSQuestion *q, char *qname, mDNSu16 qtype, const mDNSAddr *target, mDNSQuestionCallback callback)
lastsrc = zeroAddr;
if (qname) MakeDomainNameFromDNSNameString(&q->qname, qname);
q->InterfaceID = mDNSInterface_Any;
q->Target = target ? *target : zeroAddr;
q->TargetPort = MulticastDNSPort;
q->TargetQID = zeroID;
q->qtype = qtype;
q->qclass = kDNSClass_IN;
q->LongLived = mDNSfalse;
q->ExpectUnique = mDNSfalse; // Don't want to stop after the first response packet
q->ForceMCast = mDNStrue; // Query via multicast, even for apparently uDNS names like
q->ReturnIntermed = mDNStrue;
q->SuppressUnusable = mDNSfalse;
q->SearchListIndex = 0;
q->AppendSearchDomains = 0;
q->RetryWithSearchDomains = mDNSfalse;
q->TimeoutQuestion = 0;
q->WakeOnResolve = 0;
q->qnameOrig = mDNSNULL;
q->QuestionCallback = callback;
q->QuestionContext = NULL;
//mprintf("%##s %s ?\n", q->qname.c, DNSTypeName(qtype));
return(mDNS_StartQuery(&mDNSStorage, q));
mDNSlocal void DoOneQuery(DNSQuestion *q, char *qname, mDNSu16 qtype, const mDNSAddr *target, mDNSQuestionCallback callback)
mStatus status = StartQuery(q, qname, qtype, target, callback);
if (status != mStatus_NoError)
StopNow = 2;
WaitForAnswer(&mDNSStorage, 4);
mDNS_StopQuery(&mDNSStorage, q);
mDNSlocal int DoQuery(DNSQuestion *q, char *qname, mDNSu16 qtype, const mDNSAddr *target, mDNSQuestionCallback callback)
DoOneQuery(q, qname, qtype, target, callback);
if (StopNow == 0 && NumAnswers == 0 && target && target->type)
mprintf("%##s %s Trying multicast\n", q->qname.c, DNSTypeName(q->qtype));
DoOneQuery(q, qname, qtype, NULL, callback);
if (StopNow == 0 && NumAnswers == 0)
mprintf("%##s %s *** No Answer ***\n", q->qname.c, DNSTypeName(q->qtype));
mDNSlocal void HandleSIG(int signal)
(void)signal; // Unused
StopNow = 2;
mDNSexport int main(int argc, char **argv)
const char *progname = strrchr(argv[0], '/') ? strrchr(argv[0], '/') + 1 : argv[0];
int this_arg = 1;
mStatus status;
struct in_addr s4;
struct in6_addr s6;
char buffer[256];
DNSQuestion q;
if (argc < 2) goto usage;
// Since this is a special command-line tool, we want LogMsg() errors to go to stderr, not syslog
mDNS_DebugMode = mDNStrue;
// Initialise the mDNS core.
status = mDNS_Init(&mDNSStorage, &PlatformStorage,
mDNS_Init_NoInitCallback, mDNS_Init_NoInitCallbackContext);
if (status) { fprintf(stderr, "Daemon start: mDNS_Init failed %d\n", (int)status); return(status); }
signal(SIGINT, HandleSIG); // SIGINT is what you get for a Ctrl-C
signal(SIGTERM, HandleSIG);
while (this_arg < argc)
char *arg = argv[this_arg++];
if (this_arg > 2) printf("\n");
lastid = id = zeroID;
hostaddr = target = zeroAddr;
hostname[0] = hardware[0] = software[0] = 0;
NumAddr = NumAAAA = NumHINFO = 0;
if (inet_pton(AF_INET, arg, &s4) == 1)
mDNSu8 *p = (mDNSu8 *)&s4;
// 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), "", p[3], p[2], p[1], p[0]);
printf("%s\n", buffer);
target.type = mDNSAddrType_IPv4;
target.ip.v4.NotAnInteger = s4.s_addr;
DoQuery(&q, buffer, kDNSType_PTR, &target, NameCallback);
if (StopNow == 2) break;
else if (inet_pton(AF_INET6, arg, &s6) == 1)
int i;
mDNSu8 *p = (mDNSu8 *)&s6;
for (i = 0; i < 16; i++)
static const char hexValues[] = "0123456789ABCDEF";
buffer[i * 4 ] = hexValues[p[15-i] & 0x0F];
buffer[i * 4 + 1] = '.';
buffer[i * 4 + 2] = hexValues[p[15-i] >> 4];
buffer[i * 4 + 3] = '.';
mDNS_snprintf(&buffer[64], sizeof(buffer)-64, "");
target.type = mDNSAddrType_IPv6;
mDNSPlatformMemCopy(&target.ip.v6, &s6, sizeof(target.ip.v6));
DoQuery(&q, buffer, kDNSType_PTR, &target, NameCallback);
if (StopNow == 2) break;
else {
if (strlen(arg) >= sizeof(hostname)) {
fprintf(stderr, "hostname must be < %d characters\n", (int)sizeof(hostname));
goto usage;
strcpy(hostname, arg);
// Now we have the host name; get its A, AAAA, and HINFO
if (hostname[0]) DoQuery(&q, hostname, kDNSQType_ANY, &target, InfoCallback);
if (StopNow == 2) break;
if (hardware[0] || software[0])
printf("HINFO Hardware: %s\n", hardware);
printf("HINFO Software: %s\n", software);
else if (NumAnswers) printf("%s has no HINFO record\n", hostname);
else printf("Incorrect dot-local hostname, address, or no mDNSResponder running on that machine\n");
if (NumAnswers)
// Because of the way we use lastsrc in ServicesCallback, we need to clear the cache to make sure we're getting fresh answers
mDNS *const m = &mDNSStorage;
mDNSu32 slot;
CacheGroup *cg;
CacheRecord *rr;
FORALL_CACHERECORDS(slot, cg, rr) mDNS_PurgeCacheResourceRecord(m, rr);
if (target.type == 0) target = hostaddr; // Make sure the services query is targeted
DoQuery(&q, "_services._dns-sd._udp.local.", kDNSType_PTR, &target, ServicesCallback);
if (StopNow == 2) break;
fprintf(stderr, "Usage: %s <dot-local hostname> or <IPv4 address> or <IPv6 address> ...\n", progname);