[people/stevee/guardian.git] / guardian

#!/usr/bin/perl
###############################################################################
#                                                                             #
# IPFire.org - A linux based firewall                                         #
# Copyright (C) 2015  IPFire Development Team                                 #
#                                                                             #
# 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 3 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           #
# along with this program.  If not, see <http://www.gnu.org/licenses/>.       #
#                                                                             #
###############################################################################

use strict;
use threads;
use threads::shared;
use Getopt::Long;
use Thread::Queue;
use Linux::Inotify2;
use Time::HiRes qw[ time sleep ];

require Guardian::Base;
require Guardian::Config;
require Guardian::Daemon;
require Guardian::Events;
require Guardian::Logger;
require Guardian::Parser;
require Guardian::Socket;

use warnings;

# Disable warnings of unjoinded threads when stopping guardian.
no warnings 'threads';

# Define version.
my $version ="2.0";

# Get and store the given command line arguments in a hash.
my %cmdargs = ();

&GetOptions (\%cmdargs,
	'foreground|f',
	'config|c=s',
	'help|h',
	'version|v',
);

# Show help / version information.
if (defined($cmdargs{"help"})) {
	print "Guardian $version \n";
	print "Usage: guardian <optional arguments>\n";
	print " -c, --config\t\tspecifiy a configuration file other than the default (/etc/guardian/guardian.conf)\n";
	print " -f, --foreground\trun in the foreground (doesn't fork, any output goes to STDOUT)\n";
	print " -h, --help\t\tshows this help\n";
	print " -v, --version\t\tdisplay programm version and exit.\n";
	exit;
} elsif (defined($cmdargs{"version"})) {
	print "Guardian $version \n";
	exit;
}

# Check if another instance of guardian is allready running.
if (&Guardian::Daemon::IsRunning()) {
	die "Another instance of Guardian is allready running...\n";
}

# Read-in the configuration file and store the settings.
# Push the may be given config file argument.
my %mainsettings = &Guardian::Config::UseConfig($cmdargs{"config"});

# Initialize Logger.
my $logger = Guardian::Logger->Init(%mainsettings);
$logger->Log("debug", "Logger successfully initialized...");

# Add the logger object to the mainsettings for passing
# it to the modules.
$mainsettings{Logger} = $logger;

# Redirect perls "die" messages to the logger before exiting.
$SIG{__DIE__} = sub { $logger->Log("err", "@_"); };

# Initialize the event handler.
my $events = Guardian::Events->Init(%mainsettings);

# Hash to store the currently monitored files and their configured
# parsers.
my %monitored_files = ();

# Shared hash between the main process and all threads. It will store the
# monitored files and their current file position.
my %file_positions :shared = ();

# Create the main queue. It is used to store and process all events which are
# reported and enqueued by the worker threads.
my $queue :shared = new Thread::Queue or die "Could not create new, empty queue. $!";;

# Array to store all currently running worker objects.
# (Does not include the socket thread)
my @running_workers;

# Check if guardian should be daemonized or keep in the foreground.
unless (defined($cmdargs{"foreground"})) {
	# Fork into background.
	&Guardian::Daemon::Daemonize();
} else {
	# Write PID (process-id).
	&Guardian::Daemon::WritePID();
}

# Call Init function to initzialize guardian.
&Init();

# Infinite main loop, which processes all queued events.
while(1) {
	# Get the amount of elements in our queue.
	# "undef" will be returned if it is empty.
	my $current_events = $queue->pending();

	# If there is at least one element enqued
	if($current_events > 0) {
		# Grab the data of the top enqueued event.
		my $event = $queue->peek();

		# Log processed event.
		$logger->Log("debug", "QUEUE - Processed event: $event");

		# Send event data to the events parser to determine
		# if any action is required.
		$events->CheckAction($event);

		# Drop processed event from queue.
		$queue->dequeue();
	}

	# Call RemoveBlocks routine from the Events module to check
	# if items from the block list can be dropped.
	$events->RemoveBlocks();

	# Sleep 10ms to reduce the load of the main process.
	sleep(0.01);
}

#
## Init function.
#
## This function contains code which has to be executed while guardian
## is starting.
#
sub Init () {
	# Setup signal handler.
	&SignalHandler();

	# Setup IPC mechanism via Socket in an own thread.
	threads->create(\&Socket);

	# Generate hash of monitored files.
	%monitored_files = &Guardian::Base::GenerateMonitoredFiles(\%mainsettings, \%monitored_files);

	# Start worker threads.
	&StartWorkers();
}

#
## Worker function.
#
## This function is responsible for monitoring modifications of the given logfile,
## read them and pass them to the message parser.
#
## To get file modifications the inotify subsystem of the linux kernel is used.
#
## In order to prevent from permanently read and keep files opened, or dealing
## with huge logfiles, at initialization time of the worker process, the file will
## be opened once and the cursor position of the end of file (EOF) get stored. When
## reading any newly added lines from the file, we directly can jump to the last
## known position and get these lines. Afterwards, we store the current curser position
## again, so we can do it in this way over and over again.
#
## All read lines get stored in an array, which will be passed to the Parser.
#
## If any response (action) from the parser get recieved, it will be put into the
## shared event queue.
#
sub Worker ($) {
	my $file = $_[0];

	# Obtain the parser name which should be used to parser any
	# messages of this file.
	my $parser = $monitored_files{$file};

	# Signal handler to kill worker.
	$SIG{'KILL'} = sub { threads->exit(); };

	# Create inotify watcher.
	my $watcher = new Linux::Inotify2 or die "Could not use inotify. $!";

	# Monitor the specified file.
	$watcher->watch("$file", IN_MODIFY) or die "Could not monitor $file. $!";

	# Switch watcher into non-blocking mode.
	$watcher->blocking(0);

	# Log successfully spawned worker.
	$logger->Log("debug", "Spawned worker thread for: $file");

	# Infinite loop.
	while(1) {
		# Check for any events and perform them, if there
		# is a least one.
		if ($watcher->read) {
			my @message = ();

			# Obtain fileposition from hash.
			my $fileposition = $file_positions{$file};

			# Open the file.
			open (FILE, $file) or die "Could not open $file. $!";

			# Seek to the last known position.
			seek (FILE, $fileposition, 0);

			# Get the log message.
			while (my $line = <FILE>) {
				# Remove any newlines.
				chomp $line;

				# Add all lines to the message array.
				push (@message, $line);
			}

			{
				# Lock shared hash.
				lock(%file_positions);

				# Update fileposition.
				$file_positions{$file} = tell(FILE);
			}

			# Close file.
			close(FILE);

			# Send filename and message to the parser,
			# which will return if an action has to be performed.
			my @action = &Guardian::Parser::Parser("$parser", @message);

			# Send the action to the main process and put it into
			# the queue.
			if (@action) {
				# Lock the queue.
				lock($queue);

				# Put the required action into the queue.
				$queue->enqueue(@action);
			}
		} else {
			# Sleep for 10ms until the next round of the loop will start.
			sleep(0.01);
		}
	}
}

#
## Socket function.
#
## This function uses the Socket module to create and listen to an UNIX socket.
## It automatically accepts all incomming connections and pass the recieved
## data messages to the the Message_Parser function which is also part of the
## socket module.
#
## If a valid command has been sent through the socket, the corresponding event
## will be enqueued into the shared event queue.
#
sub Socket () {
	# Create the Server socket by calling the responsible function.
	my $server = &Guardian::Socket::Server();

	# Log successfull creation of socket.
	$logger->Log("debug", "Listening to Socket...");

        # Accept incomming connections from the socket.
        while (my $connection = $server->accept()) {
		# Autoflush the socket after the data
		# has been recieved.
		$connection->autoflush(1);

		# Gather all data from the connection.
		while (my $message = <$connection>) {
			# Remove any newlines.
			chomp($message);

			# Log recieved socket command.
			$logger->Log("debug", "Socket - Recieved message: $message");

			# Send the recieved data message to the
			# socket parser.
			my $action = &Guardian::Socket::Message_Parser($message);

			# If the parser returns to perform an action,
			# add it to the main event queue.
			if ($action) {
				# Lock the queue.
				lock($queue);

				# Enqueue the returned action.
				$queue->enqueue($action);
			}
		}
	}
}

#
## Function for capturing process signals.
#
## This function captures any sent process signals and will call various
## actions, basend on the captured signal.
#
sub SignalHandler {
	$SIG{INT} = \&Shutdown;
	$SIG{TERM} = \&Shutdown;
	$SIG{QUIT} = \&Shutdown;
	$SIG{HUP} = \&Reload;
}

#
## Function to start the workers (threads) for all monitored files.
#
## This function will loop through the hash of monitored files and will
## spawn an own thread based worker for each file. Every created worker will
## be added to the array of running workers.
#
sub StartWorkers () {
	# Init/Update hash which contains the cursor position of EOF.
	%file_positions = &Guardian::Base::FilePositions(\%monitored_files, \%file_positions);

	# Loop through the hash which contains the monitored files and start
	# a worker thread for each single one.
	foreach my $file (keys %monitored_files) {
		$logger->Log("debug", "Starting worker thread for $file");
		# Create worker thread for the file.
		push @running_workers, threads->create(\&Worker,$file);
	}
}

#
## Function to stop all running workers.
#
## This function is used to stop all currently running workers and will be
## called when reloading or shutting down guardian.
#
sub StopWorkers () {
	# Loop through all running workers.
	foreach my $worker (@running_workers) {
		# Send the worker the "KILL" signal and detach the
		# thread so perl can do an automatically clean-up.
		$worker->kill('KILL');
	}
	$logger->Log("debug", "All workers are stopped now...");
}

#
## Reload function.
#
## This function will get called if the signal handler recieves a "SIGHUP" signal,
## or the reload command will be sent via socket connection. It is responsible for
## reloading all configure options and stopping/starting the worker threads.
#
sub Reload () {
	# Log reload.
	$logger->Log("info", "Reload configuration...");

	# Stop all running workers.
	&StopWorkers();

	# Re-read configuration file.
	%mainsettings = &Guardian::Config::UseConfig($cmdargs{"config"});

	# Update Logger settings.
	$logger = Guardian::Logger->Init(%mainsettings);

	# Update logger object in mainsettings hash.
	$mainsettings{Logger} = $logger;

	# Re-generate hash of monitored files.
	%monitored_files = &Guardian::Base::GenerateMonitoredFiles(\%mainsettings, \%monitored_files);

	# Restart the worker threads.
	&StartWorkers();
}

#
## Shutdown function.
#
## This function is used to do a clean shutdown of guardian. It will be called
## by the signal handler when recieving INT (2), QUIT (3) and TERM (15) signals.
#
sub Shutdown () {
	# Log shutdown.
	$logger->Log("info", "Shutting down...");

	# Stop all workers.
	&StopWorkers();

	# Remove socket file on exit.
	&Guardian::Socket::RemoveSocketFile();

	# Remove pid file on exit.
	&Guardian::Daemon::RemovePIDFile();

	# Sleep for one second to give perl some
	# time to proper clean up everything before
	# exiting.
	sleep(1);

	# Log good bye message.
	$logger->Log("debug", "Good Bye!");

	# Exit guardian.
	exit;
}
Commit	Line	Data
	1	#!/usr/bin/perl
	2	###############################################################################
	3	# #
	4	# IPFire.org - A linux based firewall #
	5	# Copyright (C) 2015 IPFire Development Team #
	6	# #
	7	# This program is free software: you can redistribute it and/or modify #
	8	# it under the terms of the GNU General Public License as published by #
	9	# the Free Software Foundation, either version 3 of the License, or #
	10	# (at your option) any later version. #
	11	# #
	12	# This program is distributed in the hope that it will be useful, #
	13	# but WITHOUT ANY WARRANTY; without even the implied warranty of #
	14	# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the #
	15	# GNU General Public License for more details. #
	16	# #
	17	# You should have received a copy of the GNU General Public License #
	18	# along with this program. If not, see <http://www.gnu.org/licenses/>. #
	19	# #
	20	###############################################################################
	21
	22	use strict;
	23	use threads;
	24	use threads::shared;
	25	use Getopt::Long;
	26	use Thread::Queue;
	27	use Linux::Inotify2;
	28	use Time::HiRes qw[ time sleep ];
	29
	30	require Guardian::Base;
	31	require Guardian::Config;
	32	require Guardian::Daemon;
	33	require Guardian::Events;
	34	require Guardian::Logger;
	35	require Guardian::Parser;
	36	require Guardian::Socket;
	37
	38	use warnings;
	39
	40	# Disable warnings of unjoinded threads when stopping guardian.
	41	no warnings 'threads';
	42
	43	# Define version.
	44	my $version ="2.0";
	45
	46	# Get and store the given command line arguments in a hash.
	47	my %cmdargs = ();
	48
	49	&GetOptions (\%cmdargs,
	50	'foreground\|f',
	51	'config\|c=s',
	52	'help\|h',
	53	'version\|v',
	54	);
	55
	56	# Show help / version information.
	57	if (defined($cmdargs{"help"})) {
	58	print "Guardian $version \n";
	59	print "Usage: guardian <optional arguments>\n";
	60	print " -c, --config\t\tspecifiy a configuration file other than the default (/etc/guardian/guardian.conf)\n";
	61	print " -f, --foreground\trun in the foreground (doesn't fork, any output goes to STDOUT)\n";
	62	print " -h, --help\t\tshows this help\n";
	63	print " -v, --version\t\tdisplay programm version and exit.\n";
	64	exit;
	65	} elsif (defined($cmdargs{"version"})) {
	66	print "Guardian $version \n";
	67	exit;
	68	}
	69
	70	# Check if another instance of guardian is allready running.
	71	if (&Guardian::Daemon::IsRunning()) {
	72	die "Another instance of Guardian is allready running...\n";
	73	}
	74
	75	# Read-in the configuration file and store the settings.
	76	# Push the may be given config file argument.
	77	my %mainsettings = &Guardian::Config::UseConfig($cmdargs{"config"});
	78
	79	# Initialize Logger.
	80	my $logger = Guardian::Logger->Init(%mainsettings);
	81	$logger->Log("debug", "Logger successfully initialized...");
	82
	83	# Add the logger object to the mainsettings for passing
	84	# it to the modules.
	85	$mainsettings{Logger} = $logger;
	86
	87	# Redirect perls "die" messages to the logger before exiting.
	88	$SIG{__DIE__} = sub { $logger->Log("err", "@_"); };
	89
	90	# Initialize the event handler.
	91	my $events = Guardian::Events->Init(%mainsettings);
	92
	93	# Hash to store the currently monitored files and their configured
	94	# parsers.
	95	my %monitored_files = ();
	96
	97	# Shared hash between the main process and all threads. It will store the
	98	# monitored files and their current file position.
	99	my %file_positions :shared = ();
	100
	101	# Create the main queue. It is used to store and process all events which are
	102	# reported and enqueued by the worker threads.
	103	my $queue :shared = new Thread::Queue or die "Could not create new, empty queue. $!";;
	104
	105	# Array to store all currently running worker objects.
	106	# (Does not include the socket thread)
	107	my @running_workers;
	108
	109	# Check if guardian should be daemonized or keep in the foreground.
	110	unless (defined($cmdargs{"foreground"})) {
	111	# Fork into background.
	112	&Guardian::Daemon::Daemonize();
	113	} else {
	114	# Write PID (process-id).
	115	&Guardian::Daemon::WritePID();
	116	}
	117
	118	# Call Init function to initzialize guardian.
	119	&Init();
	120
	121	# Infinite main loop, which processes all queued events.
	122	while(1) {
	123	# Get the amount of elements in our queue.
	124	# "undef" will be returned if it is empty.
	125	my $current_events = $queue->pending();
	126
	127	# If there is at least one element enqued
	128	if($current_events > 0) {
	129	# Grab the data of the top enqueued event.
	130	my $event = $queue->peek();
	131
	132	# Log processed event.
	133	$logger->Log("debug", "QUEUE - Processed event: $event");
	134
	135	# Send event data to the events parser to determine
	136	# if any action is required.
	137	$events->CheckAction($event);
	138
	139	# Drop processed event from queue.
	140	$queue->dequeue();
	141	}
	142
	143	# Call RemoveBlocks routine from the Events module to check
	144	# if items from the block list can be dropped.
	145	$events->RemoveBlocks();
	146
	147	# Sleep 10ms to reduce the load of the main process.
	148	sleep(0.01);
	149	}
	150
	151	#
	152	## Init function.
	153	#
	154	## This function contains code which has to be executed while guardian
	155	## is starting.
	156	#
	157	sub Init () {
	158	# Setup signal handler.
	159	&SignalHandler();
	160
	161	# Setup IPC mechanism via Socket in an own thread.
	162	threads->create(\&Socket);
	163
	164	# Generate hash of monitored files.
	165	%monitored_files = &Guardian::Base::GenerateMonitoredFiles(\%mainsettings, \%monitored_files);
	166
	167	# Start worker threads.
	168	&StartWorkers();
	169	}
	170
	171	#
	172	## Worker function.
	173	#
	174	## This function is responsible for monitoring modifications of the given logfile,
	175	## read them and pass them to the message parser.
	176	#
	177	## To get file modifications the inotify subsystem of the linux kernel is used.
	178	#
	179	## In order to prevent from permanently read and keep files opened, or dealing
	180	## with huge logfiles, at initialization time of the worker process, the file will
	181	## be opened once and the cursor position of the end of file (EOF) get stored. When
	182	## reading any newly added lines from the file, we directly can jump to the last
	183	## known position and get these lines. Afterwards, we store the current curser position
	184	## again, so we can do it in this way over and over again.
	185	#
	186	## All read lines get stored in an array, which will be passed to the Parser.
	187	#
	188	## If any response (action) from the parser get recieved, it will be put into the
	189	## shared event queue.
	190	#
	191	sub Worker ($) {
	192	my $file = $_[0];
	193
	194	# Obtain the parser name which should be used to parser any
	195	# messages of this file.
	196	my $parser = $monitored_files{$file};
	197
	198	# Signal handler to kill worker.
	199	$SIG{'KILL'} = sub { threads->exit(); };
	200
	201	# Create inotify watcher.
	202	my $watcher = new Linux::Inotify2 or die "Could not use inotify. $!";
	203
	204	# Monitor the specified file.
	205	$watcher->watch("$file", IN_MODIFY) or die "Could not monitor $file. $!";
	206
	207	# Switch watcher into non-blocking mode.
	208	$watcher->blocking(0);
	209
	210	# Log successfully spawned worker.
	211	$logger->Log("debug", "Spawned worker thread for: $file");
	212
	213	# Infinite loop.
	214	while(1) {
	215	# Check for any events and perform them, if there
	216	# is a least one.
	217	if ($watcher->read) {
	218	my @message = ();
	219
	220	# Obtain fileposition from hash.
	221	my $fileposition = $file_positions{$file};
	222
	223	# Open the file.
	224	open (FILE, $file) or die "Could not open $file. $!";
	225
	226	# Seek to the last known position.
	227	seek (FILE, $fileposition, 0);
	228
	229	# Get the log message.
	230	while (my $line = <FILE>) {
	231	# Remove any newlines.
	232	chomp $line;
	233
	234	# Add all lines to the message array.
	235	push (@message, $line);
	236	}
	237
	238	{
	239	# Lock shared hash.
	240	lock(%file_positions);
	241
	242	# Update fileposition.
	243	$file_positions{$file} = tell(FILE);
	244	}
	245
	246	# Close file.
	247	close(FILE);
	248
	249	# Send filename and message to the parser,
	250	# which will return if an action has to be performed.
	251	my @action = &Guardian::Parser::Parser("$parser", @message);
	252
	253	# Send the action to the main process and put it into
	254	# the queue.
	255	if (@action) {
	256	# Lock the queue.
	257	lock($queue);
	258
	259	# Put the required action into the queue.
	260	$queue->enqueue(@action);
	261	}
	262	} else {
	263	# Sleep for 10ms until the next round of the loop will start.
	264	sleep(0.01);
	265	}
	266	}
	267	}
	268
	269	#
	270	## Socket function.
	271	#
	272	## This function uses the Socket module to create and listen to an UNIX socket.
	273	## It automatically accepts all incomming connections and pass the recieved
	274	## data messages to the the Message_Parser function which is also part of the
	275	## socket module.
	276	#
	277	## If a valid command has been sent through the socket, the corresponding event
	278	## will be enqueued into the shared event queue.
	279	#
	280	sub Socket () {
	281	# Create the Server socket by calling the responsible function.
	282	my $server = &Guardian::Socket::Server();
	283
	284	# Log successfull creation of socket.
	285	$logger->Log("debug", "Listening to Socket...");
	286
	287	# Accept incomming connections from the socket.
	288	while (my $connection = $server->accept()) {
	289	# Autoflush the socket after the data
	290	# has been recieved.
	291	$connection->autoflush(1);
	292
	293	# Gather all data from the connection.
	294	while (my $message = <$connection>) {
	295	# Remove any newlines.
	296	chomp($message);
	297
	298	# Log recieved socket command.
	299	$logger->Log("debug", "Socket - Recieved message: $message");
	300
	301	# Send the recieved data message to the
	302	# socket parser.
	303	my $action = &Guardian::Socket::Message_Parser($message);
	304
	305	# If the parser returns to perform an action,
	306	# add it to the main event queue.
	307	if ($action) {
	308	# Lock the queue.
	309	lock($queue);
	310
	311	# Enqueue the returned action.
	312	$queue->enqueue($action);
	313	}
	314	}
	315	}
	316	}
	317
	318	#
	319	## Function for capturing process signals.
	320	#
	321	## This function captures any sent process signals and will call various
	322	## actions, basend on the captured signal.
	323	#
	324	sub SignalHandler {
	325	$SIG{INT} = \&Shutdown;
	326	$SIG{TERM} = \&Shutdown;
	327	$SIG{QUIT} = \&Shutdown;
	328	$SIG{HUP} = \&Reload;
	329	}
	330
	331	#
	332	## Function to start the workers (threads) for all monitored files.
	333	#
	334	## This function will loop through the hash of monitored files and will
	335	## spawn an own thread based worker for each file. Every created worker will
	336	## be added to the array of running workers.
	337	#
	338	sub StartWorkers () {
	339	# Init/Update hash which contains the cursor position of EOF.
	340	%file_positions = &Guardian::Base::FilePositions(\%monitored_files, \%file_positions);
	341
	342	# Loop through the hash which contains the monitored files and start
	343	# a worker thread for each single one.
	344	foreach my $file (keys %monitored_files) {
	345	$logger->Log("debug", "Starting worker thread for $file");
	346	# Create worker thread for the file.
	347	push @running_workers, threads->create(\&Worker,$file);
	348	}
	349	}
	350
	351	#
	352	## Function to stop all running workers.
	353	#
	354	## This function is used to stop all currently running workers and will be
	355	## called when reloading or shutting down guardian.
	356	#
	357	sub StopWorkers () {
	358	# Loop through all running workers.
	359	foreach my $worker (@running_workers) {
	360	# Send the worker the "KILL" signal and detach the
	361	# thread so perl can do an automatically clean-up.
	362	$worker->kill('KILL');
	363	}
	364	$logger->Log("debug", "All workers are stopped now...");
	365	}
	366
	367	#
	368	## Reload function.
	369	#
	370	## This function will get called if the signal handler recieves a "SIGHUP" signal,
	371	## or the reload command will be sent via socket connection. It is responsible for
	372	## reloading all configure options and stopping/starting the worker threads.
	373	#
	374	sub Reload () {
	375	# Log reload.
	376	$logger->Log("info", "Reload configuration...");
	377
	378	# Stop all running workers.
	379	&StopWorkers();
	380
	381	# Re-read configuration file.
	382	%mainsettings = &Guardian::Config::UseConfig($cmdargs{"config"});
	383
	384	# Update Logger settings.
	385	$logger = Guardian::Logger->Init(%mainsettings);
	386
	387	# Update logger object in mainsettings hash.
	388	$mainsettings{Logger} = $logger;
	389
	390	# Re-generate hash of monitored files.
	391	%monitored_files = &Guardian::Base::GenerateMonitoredFiles(\%mainsettings, \%monitored_files);
	392
	393	# Restart the worker threads.
	394	&StartWorkers();
	395	}
	396
	397	#
	398	## Shutdown function.
	399	#
	400	## This function is used to do a clean shutdown of guardian. It will be called
	401	## by the signal handler when recieving INT (2), QUIT (3) and TERM (15) signals.
	402	#
	403	sub Shutdown () {
	404	# Log shutdown.
	405	$logger->Log("info", "Shutting down...");
	406
	407	# Stop all workers.
	408	&StopWorkers();
	409
	410	# Remove socket file on exit.
	411	&Guardian::Socket::RemoveSocketFile();
	412
	413	# Remove pid file on exit.
	414	&Guardian::Daemon::RemovePIDFile();
	415
	416	# Sleep for one second to give perl some
	417	# time to proper clean up everything before
	418	# exiting.
	419	sleep(1);
	420
	421	# Log good bye message.
	422	$logger->Log("debug", "Good Bye!");
	423
	424	# Exit guardian.
	425	exit;
	426	}