/********************************************************************\
  * BitlBee -- An IRC to other IM-networks gateway                     *
  *                                                                    *
  * Copyright 2002-2004 Wilmer van der Gaast and others                *
  \********************************************************************/

/* Main file (Unix specific part)                                       */

/*
  This program is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation; either version 2 of the License, or
  (at your option) any later version.

  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License with
  the Debian GNU/Linux distribution in /usr/share/common-licenses/GPL;
  if not, write to the Free Software Foundation, Inc., 59 Temple Place,
  Suite 330, Boston, MA  02111-1307  USA
*/

#include "bitlbee.h"
#include "commands.h"
#include "crypting.h"
#include "protocols/nogaim.h"
#include "help.h"
#include "ipc.h"
#include <signal.h>
#include <unistd.h>
#include <sys/time.h>
#include <sys/wait.h>
#include <pwd.h>

global_t global;	/* Against global namespace pollution */

static void sighandler( int signal );

int main( int argc, char *argv[], char **envp )
{
	int i = 0;
	char *old_cwd = NULL;
	struct sigaction sig, old;
	
	log_init();
	global.conf_file = g_strdup( CONF_FILE_DEF );
	global.conf = conf_load( argc, argv );
	if( global.conf == NULL )
		return( 1 );
	
	b_main_init();
	nogaim_init();
	
	srand( time( NULL ) ^ getpid() );
	global.helpfile = g_strdup( HELP_FILE );
	
	if( global.conf->runmode == RUNMODE_INETD )
	{
		i = bitlbee_inetd_init();
		log_message( LOGLVL_INFO, "Bitlbee %s starting in inetd mode.", BITLBEE_VERSION );

	}
	else if( global.conf->runmode == RUNMODE_DAEMON )
	{
		i = bitlbee_daemon_init();
		log_message( LOGLVL_INFO, "Bitlbee %s starting in daemon mode.", BITLBEE_VERSION );
	}
	else if( global.conf->runmode == RUNMODE_FORKDAEMON )
	{
		/* In case the operator requests a restart, we need this. */
		old_cwd = g_malloc( 256 );
		if( getcwd( old_cwd, 255 ) == NULL )
		{
			log_message( LOGLVL_WARNING, "Could not save current directory: %s", strerror( errno ) );
			g_free( old_cwd );
			old_cwd = NULL;
		}
		
		i = bitlbee_daemon_init();
		log_message( LOGLVL_INFO, "Bitlbee %s starting in forking daemon mode.", BITLBEE_VERSION );
	}
	if( i != 0 )
		return( i );
	
	if( ( global.conf->user && *global.conf->user ) &&
	    ( global.conf->runmode == RUNMODE_DAEMON || 
	      global.conf->runmode == RUNMODE_FORKDAEMON ) &&
	    ( !getuid() || !geteuid() ) )
	{
		struct passwd *pw = NULL;
		pw = getpwnam( global.conf->user );
		if( pw )
		{
			setgid( pw->pw_gid );
			setuid( pw->pw_uid );
		}
	}

	global.storage = storage_init( global.conf->primary_storage, global.conf->migrate_storage );
	if( global.storage == NULL )
	{
		log_message( LOGLVL_ERROR, "Unable to load storage backend '%s'", global.conf->primary_storage );
		return( 1 );
	}
 	
	/* Catch some signals to tell the user what's happening before quitting */
	memset( &sig, 0, sizeof( sig ) );
	sig.sa_handler = sighandler;
	sigaction( SIGCHLD, &sig, &old );
	sigaction( SIGPIPE, &sig, &old );
	sig.sa_flags = SA_RESETHAND;
	sigaction( SIGINT,  &sig, &old );
	sigaction( SIGILL,  &sig, &old );
	sigaction( SIGBUS,  &sig, &old );
	sigaction( SIGFPE,  &sig, &old );
	sigaction( SIGSEGV, &sig, &old );
	sigaction( SIGTERM, &sig, &old );
	sigaction( SIGQUIT, &sig, &old );
	sigaction( SIGXCPU, &sig, &old );
	
	if( !getuid() || !geteuid() )
		log_message( LOGLVL_WARNING, "BitlBee is running with root privileges. Why?" );
	if( help_init( &global.help, global.helpfile ) == NULL )
		log_message( LOGLVL_WARNING, "Error opening helpfile %s.", HELP_FILE );
	
	b_main_run();
	
	/* Mainly good for restarting, to make sure we close the help.txt fd. */
	help_free( &global.help );
	
	if( global.restart )
	{
		char *fn = ipc_master_save_state();
		char **args;
		int n, i;
		
		chdir( old_cwd );
		
		n = 0;
		args = g_new0( char *, argc + 3 );
		args[n++] = argv[0];
		if( fn )
		{
			args[n++] = "-R";
			args[n++] = fn;
		}
		for( i = 1; argv[i] && i < argc; i ++ )
		{
			if( strcmp( argv[i], "-R" ) == 0 )
				i += 2;
			
			args[n++] = argv[i];
		}
		
		close( global.listen_socket );
		
		execve( args[0], args, envp );
	}
	
	return( 0 );
}

static void sighandler( int signal )
{
	/* FIXME: Calling log_message() here is not a very good idea! */
	
	if( signal == SIGTERM )
	{
		static int first = 1;
		
		if( first )
		{
			/* We don't know what we were doing when this signal came in. It's not safe to touch
			   the user data now (not to mention writing them to disk), so add a timer. */
			
			log_message( LOGLVL_ERROR, "SIGTERM received, cleaning up process." );
			b_timeout_add( 1, (b_event_handler) bitlbee_shutdown, NULL );
			
			first = 0;
		}
		else
		{
			/* Well, actually, for now we'll never need this part because this signal handler
			   will never be called more than once in a session for a non-SIGPIPE signal...
			   But just in case we decide to change that: */
			
			log_message( LOGLVL_ERROR, "SIGTERM received twice, so long for a clean shutdown." );
			raise( signal );
		}
	}
	else if( signal == SIGCHLD )
	{
		pid_t pid;
		int st;
		
		while( ( pid = waitpid( 0, &st, WNOHANG ) ) > 0 )
		{
			if( WIFSIGNALED( st ) )
				log_message( LOGLVL_INFO, "Client %d terminated normally. (status = %d)", (int) pid, WEXITSTATUS( st ) );
			else if( WIFEXITED( st ) )
				log_message( LOGLVL_INFO, "Client %d killed by signal %d.", (int) pid, WTERMSIG( st ) );
		}
	}
	else if( signal != SIGPIPE )
	{
		log_message( LOGLVL_ERROR, "Fatal signal received: %d. That's probably a bug.", signal );
		raise( signal );
	}
}

double gettime()
{
	struct timeval time[1];

	gettimeofday( time, 0 );
	return( (double) time->tv_sec + (double) time->tv_usec / 1000000 );
}

/* A pretty reliable random number generator. Tries to use the /dev/random
   devices first, and falls back to the random number generator from libc
   when it fails. Opens randomizer devices with O_NONBLOCK to make sure a
   lack of entropy won't halt BitlBee. */
void random_bytes( unsigned char *buf, int count )
{
	static int use_dev = -1;
	
	/* Actually this probing code isn't really necessary, is it? */
	if( use_dev == -1 )
	{
		if( access( "/dev/random", R_OK ) == 0 || access( "/dev/urandom", R_OK ) == 0 )
			use_dev = 1;
		else
		{
			use_dev = 0;
			srand( ( getpid() << 16 ) ^ time( NULL ) );
		}
	}
	
	if( use_dev )
	{
		int fd;
		
		/* At least on Linux, /dev/random can block if there's not
		   enough entropy. We really don't want that, so if it can't
		   give anything, use /dev/urandom instead. */
		if( ( fd = open( "/dev/random", O_RDONLY | O_NONBLOCK ) ) >= 0 )
			if( read( fd, buf, count ) == count )
			{
				close( fd );
				return;
			}
		close( fd );
		
		/* urandom isn't supposed to block at all, but just to be
		   sure. If it blocks, we'll disable use_dev and use the libc
		   randomizer instead. */
		if( ( fd = open( "/dev/urandom", O_RDONLY | O_NONBLOCK ) ) >= 0 )
			if( read( fd, buf, count ) == count )
			{
				close( fd );
				return;
			}
		close( fd );
		
		/* If /dev/random blocks once, we'll still try to use it
		   again next time. If /dev/urandom also fails for some
		   reason, stick with libc during this session. */
		
		use_dev = 0;
		srand( ( getpid() << 16 ) ^ time( NULL ) );
	}
	
	if( !use_dev )
	{
		int i;
		
		/* Possibly the LSB of rand() isn't very random on some
		   platforms. Seems okay on at least Linux and OSX though. */
		for( i = 0; i < count; i ++ )
			buf[i] = rand() & 0xff;
	}
}