PosixDaemon.c   [plain text]


/* -*- Mode: C; tab-width: 4 -*-
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 * Copyright (c) 2003-2004 Apple Computer, Inc. All rights reserved.
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	File:		daemon.c

	Contains:	main & associated Application layer for mDNSResponder on Linux.

	Change History (most recent first):

$Log: PosixDaemon.c,v $
Revision 1.25  2005/01/27 20:01:50  cheshire
udsSupportRemoveFDFromEventLoop() needs to close the file descriptor as well

Revision 1.24  2005/01/19 19:20:49  ksekar
<rdar://problem/3960191> Need a way to turn off domain discovery

Revision 1.23  2004/12/16 20:17:11  cheshire
<rdar://problem/3324626> Cache memory management improvements

Revision 1.22  2004/12/10 13:12:08  cheshire
Create no-op function RecordUpdatedNiceLabel(), required by uds_daemon.c

Revision 1.21  2004/12/01 20:57:20  ksekar
<rdar://problem/3873921> Wide Area Rendezvous must be split-DNS aware

Revision 1.20  2004/12/01 04:28:43  cheshire
<rdar://problem/3872803> Darwin patches for Solaris and Suse
Use version of daemon() provided in mDNSUNP.c instead of local copy

Revision 1.19  2004/12/01 03:30:29  cheshire
<rdar://problem/3889346> Add Unicast DNS support to mDNSPosix

Revision 1.18  2004/11/30 22:45:59  cheshire
Minor code tidying

Revision 1.17  2004/11/30 22:18:59  cheshire
<rdar://problem/3889351> Posix needs to read the list of unicast DNS servers and set server list

Revision 1.16  2004/09/21 21:05:12	cheshire
Move duplicate code out of mDNSMacOSX/daemon.c and mDNSPosix/PosixDaemon.c,
into mDNSShared/uds_daemon.c

Revision 1.15  2004/09/17 01:08:53	cheshire
Renamed mDNSClientAPI.h to mDNSEmbeddedAPI.h
  The name "mDNSClientAPI.h" is misleading to new developers looking at this code. The interfaces
  declared in that file are ONLY appropriate to single-address-space embedded applications.
  For clients on general-purpose computers, the interfaces defined in dns_sd.h should be used.

Revision 1.14  2004/09/16 00:24:49	cheshire
<rdar://problem/3803162> Fix unsafe use of mDNSPlatformTimeNow()

Revision 1.13  2004/08/11 01:59:41	cheshire
Remove "mDNS *globalInstance" parameter from udsserver_init()

Revision 1.12  2004/06/28 23:19:19	cheshire
Fix "Daemon_Init declared but never defined" warning on Linux

Revision 1.11  2004/06/25 00:26:27	rpantos
Changes to fix the Posix build on Solaris.

Revision 1.10  2004/06/08 04:59:40	cheshire
Tidy up wording -- log messages are already prefixed with "mDNSResponder", so don't need to repeat it

Revision 1.9  2004/05/29 00:14:20  rpantos
<rdar://problem/3508093> Runtime check to disable prod mdnsd on OS X.

Revision 1.8  2004/04/07 01:19:04  cheshire
Hash slot value should be unsigned

Revision 1.7  2004/02/14 06:34:57  cheshire
Use LogMsg instead of fprintf( stderr

Revision 1.6  2004/02/14 01:10:42  rpantos
Allow daemon to run if 'nobody' is not defined, with a warning. (For Roku HD1000.)

Revision 1.5  2004/02/05 07:45:43  cheshire
Add Log header

Revision 1.4  2004/01/28 21:14:23  cheshire
Reconcile debug_mode and gDebugLogging into a single flag (mDNS_DebugMode)

Revision 1.3  2004/01/19 19:51:46  cheshire
Fix compiler error (mixed declarations and code) on some versions of Linux

Revision 1.2  2003/12/11 03:03:51  rpantos
Clean up mDNSPosix so that it builds on OS X again.

Revision 1.1  2003/12/08 20:47:02  rpantos
Add support for mDNSResponder on Linux.
*/

#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>
#include <signal.h>
#include <errno.h>
#include <fcntl.h>
#include <pwd.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#include "mDNSEmbeddedAPI.h"
#include "mDNSDebug.h"
#include "mDNSPosix.h"
#include "uds_daemon.h"
#include "PlatformCommon.h"

#define uDNS_SERVERS_FILE "/etc/resolv.conf"

#define CONFIG_FILE "/etc/mdnsd.conf"
static domainname DynDNSZone;                // Default wide-area zone for service registration
static domainname DynDNSHostname;

#define RR_CACHE_SIZE 500
static CacheEntity gRRCache[RR_CACHE_SIZE];

extern const char mDNSResponderVersionString[];

static int ParseDNSServers(mDNS *m, const char *filePath)
	{
	char line[256];
	char nameserver[16];
	char keyword[10];
	int  numOfServers = 0;
	FILE *fp = fopen(filePath, "r");
	if (fp == NULL) return -1;
	while (fgets(line,sizeof(line),fp))
		{
		struct in_addr ina;
		line[255]='\0';		// just to be safe
		if (sscanf(line,"%10s %15s", keyword, nameserver) != 2) continue;	// it will skip whitespaces
		if (strncmp(keyword,"nameserver",10)) continue;
		if (inet_aton(nameserver, (struct in_addr *)&ina) != 0)
			{
			mDNSAddr DNSAddr;
			DNSAddr.type = mDNSAddrType_IPv4;
			DNSAddr.ip.v4.NotAnInteger = ina.s_addr;
			mDNS_AddDNSServer(m, &DNSAddr, NULL);
			numOfServers++;
			}
		}  
	return (numOfServers > 0) ? 0 : -1;
	}

static void Reconfigure(mDNS *m)
	{
	mDNSAddr DynDNSIP;
	mDNS_SetPrimaryInterfaceInfo(m, NULL, NULL);
	mDNS_DeleteDNSServers(m);
	if (ParseDNSServers(m, uDNS_SERVERS_FILE) < 0)
		LogMsg("Unable to parse DNS server list. Unicast DNS-SD unavailable");
	ReadDDNSSettingsFromConfFile(m, CONFIG_FILE, &DynDNSHostname, &DynDNSZone, NULL);
	FindDefaultRouteIP(&DynDNSIP);
	if (DynDNSHostname.c[0]) mDNS_AddDynDNSHostName(m, &DynDNSHostname, NULL, NULL);
	if (DynDNSIP.type)       mDNS_SetPrimaryInterfaceInfo(m, &DynDNSIP, NULL);
	}

// Do appropriate things at startup with command line arguments. Calls exit() if unhappy.
static void ParseCmdLinArgs(int argc, char **argv)
	{
	if (argc > 1)
		{
		if (0 == strcmp(argv[1], "-debug")) mDNS_DebugMode = mDNStrue;
		else printf("Usage: mDNSResponder [-debug]\n");
		}

	if (!mDNS_DebugMode)
		{
		int result = daemon(0, 0);
		if (result != 0) { LogMsg("Could not run as daemon - exiting"); exit(result); }
#if __APPLE__
		LogMsg("The POSIX mDNSResponder should only be used on OS X for testing - exiting");
		exit(-1);
#endif
		}
	}

static void		DumpStateLog(mDNS *const m)
// Dump a little log of what we've been up to.
	{
	LogMsgIdent(mDNSResponderVersionString, "---- BEGIN STATE LOG ----");
	udsserver_info(m);
	LogMsgIdent(mDNSResponderVersionString, "----  END STATE LOG  ----");
	}

static mStatus	MainLoop(mDNS *m) // Loop until we quit.
	{
	sigset_t	signals;
	mDNSBool	gotData = mDNSfalse;

	mDNSPosixListenForSignalInEventLoop(SIGINT);
	mDNSPosixListenForSignalInEventLoop(SIGTERM);
	mDNSPosixListenForSignalInEventLoop(SIGUSR1);
	mDNSPosixListenForSignalInEventLoop(SIGPIPE);
	mDNSPosixListenForSignalInEventLoop(SIGHUP) ;

	for (; ;)
		{
		// Work out how long we expect to sleep before the next scheduled task
		struct timeval	timeout;
		mDNSs32			ticks;

		// Only idle if we didn't find any data the last time around
		if (!gotData)
			{
			mDNSs32			nextTimerEvent = mDNS_Execute(m);
			nextTimerEvent = udsserver_idle(nextTimerEvent);
			ticks = nextTimerEvent - mDNS_TimeNow(m);
			if (ticks < 1) ticks = 1;
			}
		else	// otherwise call EventLoop again with 0 timemout
			ticks = 0;

		timeout.tv_sec = ticks / mDNSPlatformOneSecond;
		timeout.tv_usec = (ticks % mDNSPlatformOneSecond) * 1000000 / mDNSPlatformOneSecond;

		(void) mDNSPosixRunEventLoopOnce(m, &timeout, &signals, &gotData);

		if (sigismember(&signals, SIGHUP )) Reconfigure(m);
		if (sigismember(&signals, SIGUSR1)) DumpStateLog(m);
		// SIGPIPE happens when we try to write to a dead client; death should be detected soon in request_callback() and cleaned up.
		if (sigismember(&signals, SIGPIPE)) LogMsg("Received SIGPIPE - ignoring");
		if (sigismember(&signals, SIGINT) || sigismember(&signals, SIGTERM)) break;
		}
	return EINTR;
	}

int		main(int argc, char **argv)
	{
	#define mDNSRecord mDNSStorage
	mDNS_PlatformSupport	platformStorage;
	mStatus					err;

	bzero(&mDNSRecord, sizeof mDNSRecord);
	bzero(&platformStorage, sizeof platformStorage);

	ParseCmdLinArgs(argc, argv);

	err = mDNS_Init(&mDNSRecord, &platformStorage, gRRCache, RR_CACHE_SIZE, mDNS_Init_AdvertiseLocalAddresses, 
					mDNS_Init_NoInitCallback, mDNS_Init_NoInitCallbackContext); 

	if (mStatus_NoError == err)
		err = udsserver_init();
		
	Reconfigure(&mDNSRecord);

	// Now that we're finished with anything privileged, switch over to running as "nobody"
	if (mStatus_NoError == err)
		{
		const struct passwd *pw = getpwnam("nobody");
		if (pw != NULL)
			setuid(pw->pw_uid);
		else
			LogMsg("WARNING: mdnsd continuing as root because user \"nobody\" does not exist");
		}

	if (mStatus_NoError == err)
		err = MainLoop(&mDNSRecord);
 
	mDNS_Close(&mDNSRecord);

	if (udsserver_exit() < 0)
		LogMsg("ExitCallback: udsserver_exit failed");
 
 #if MDNS_DEBUGMSGS > 0
	printf("mDNSResponder exiting normally with %ld\n", err);
 #endif
 
	return err;
	}

//		uds_daemon support		////////////////////////////////////////////////////////////

#if MDNS_MALLOC_DEBUGGING >= 2
#define LogMalloc LogMsg
#else
#define LogMalloc(ARGS...) ((void)0)
#endif

mStatus udsSupportAddFDToEventLoop(int fd, udsEventCallback callback, void *context)
/* Support routine for uds_daemon.c */
	{
	// Depends on the fact that udsEventCallback == mDNSPosixEventCallback
	return mDNSPosixAddFDToEventLoop(fd, callback, context);
	}

mStatus udsSupportRemoveFDFromEventLoop(int fd)		// Note: This also CLOSES the file descriptor
	{
	return mDNSPosixRemoveFDFromEventLoop(fd);
	close(fd);
	}

mDNSexport void RecordUpdatedNiceLabel(mDNS *const m, mDNSs32 delay)
	{
	(void)m;
	(void)delay;
	// No-op, for now
	}

#if MACOSX_MDNS_MALLOC_DEBUGGING >= 1

void *mallocL(char *msg, unsigned int size)
	{
	unsigned long *mem = malloc(size+8);
	if (!mem)
		{
		LogMsg("malloc( %s : %d ) failed", msg, size);
		return(NULL); 
		}
	else
		{
		LogMalloc("malloc( %s : %lu ) = %p", msg, size, &mem[2]);
		mem[0] = 0xDEAD1234;
		mem[1] = size;
		//bzero(&mem[2], size);
		memset(&mem[2], 0xFF, size);
//		validatelists(&mDNSStorage);
		return(&mem[2]);
		}
	}

void freeL(char *msg, void *x)
	{
	if (!x)
		LogMsg("free( %s @ NULL )!", msg);
	else
		{
		unsigned long *mem = ((unsigned long *)x) - 2;
		if (mem[0] != 0xDEAD1234)
			{ LogMsg("free( %s @ %p ) !!!! NOT ALLOCATED !!!!", msg, &mem[2]); return; }
		if (mem[1] > 8000)
			{ LogMsg("free( %s : %ld @ %p) too big!", msg, mem[1], &mem[2]); return; }
		LogMalloc("free( %s : %ld @ %p)", msg, mem[1], &mem[2]);
		//bzero(mem, mem[1]+8);
		memset(mem, 0xDD, mem[1]+8);
//		validatelists(&mDNSStorage);
		free(mem);
		}
	}

#endif // MACOSX_MDNS_MALLOC_DEBUGGING >= 1

// For convenience when using the "strings" command, this is the last thing in the file
#if mDNSResponderVersion > 1
mDNSexport const char mDNSResponderVersionString[] = "mDNSResponder-" STRINGIFY(mDNSResponderVersion) " (" __DATE__ " " __TIME__ ") ";
#else
mDNSexport const char mDNSResponderVersionString[] = "mDNSResponder (Engineering Build) (" __DATE__ " " __TIME__ ") ";
#endif