From 0b0ec9b4ecb7c599b17579bc98ef44e4dbf4771f Mon Sep 17 00:00:00 2001
From: Stefan Schantl <stefan.schantl@ipfire.org>
Date: Fri, 20 Nov 2015 22:37:29 +0100
Subject: [PATCH] Add "Socket" module.

The Socket module provides an IPC mechanism for guardian, based
on a UNIX socket. It contains a server, a client and a message parser
function which easily can be re-used.

Signed-off-by: Stefan Schantl <stefan.schantl@ipfire.org>
---
 modules/Socket.pm | 117 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 117 insertions(+)
 create mode 100644 modules/Socket.pm

diff --git a/modules/Socket.pm b/modules/Socket.pm
new file mode 100644
index 0000000..c8a17c9
--- /dev/null
+++ b/modules/Socket.pm
@@ -0,0 +1,117 @@
+package Guardian::Socket;
+use strict;
+use warnings;
+
+use Exporter qw(import);
+
+our @EXPORT_OK = qw(Server Client Message_Parser);
+
+use IO::Socket::UNIX qw( SOCK_STREAM SOMAXCONN );
+
+# The path and filename to the UNIX socket.
+my $socketpath = "/run/guardian";
+my $socketfile = "/run/guardian/guardian.sock";
+
+# Hash with all supported socket commands and events which should
+# be returned by the parser.
+my %supported_commands = (
+	'block' => 'block',
+	'unblock' => 'unblock',
+	'flush' => 'flush',
+	'reload' => 'reload',
+	'logrotate' => 'logrotate',
+);
+
+#
+## Socket server function.
+#
+## It is used to create the server component to provide an IPC
+## mechanism for guardian.  The server function creates an UNIX
+## socket.
+#
+sub Server () {
+	# If the path for the socketfile does not exist, try to
+	# create it.
+	unless (-d "$socketpath") {
+		mkdir("$socketpath") or die "Could not create $socketpath: $@\n";
+	}
+
+	# Delete an existing socket file.
+	if (-s "$socketfile") {
+		unlink "$socketfile" 
+		or die "Could not release existing socket file: $@\n";
+	}
+
+	# Create a new UNIX socket.
+	my $server = IO::Socket::UNIX->new(
+		Local => $socketfile,
+		Listen => SOMAXCONN,
+		Type => SOCK_STREAM,
+	) or die "Could not create socket: $@\n";
+
+	# Return the server object.
+	return $server;
+}
+
+#
+## A client for the socket server.
+#
+## This function provides a simple client to connect to the server socket
+## and send messages through it to a running guardian process.
+#
+sub Client($) {
+	my ($message) = @_;
+
+	# Create the client and connect to the server socket.
+	my $client = IO::Socket::UNIX->new(
+		Type => SOCK_STREAM,
+		Peer => $socketfile,
+	) or die "Could not connect to socketfile: $!\n";
+
+	# Remove any newline.
+	chomp($message);
+
+	# Send the message through the socket.
+	print $client "$message\n";
+}
+
+#
+## The Socket message parser.
+#
+## This subfunction is responsible for parsing any data or messages
+## which have been recieved through the server socket.
+#
+sub Message_Parser ($) {
+	# Splitt the message into single parts.
+	# The first part contains the command, the second
+	# one an optional argument.
+	my @message = split(/ /, $_[0]);
+	my ($command, $optarg, $unsupported) = @message;
+
+	# Currently only socket messages with two arguments (command and
+	# the additional argument which is required for some commands)
+	# are supported. If a third argument is passed, the message
+	# is invalid and the parser returns false.
+	if ($unsupported) {
+		return undef;
+	}
+
+	# Check if we got a supported command.
+	if (exists $supported_commands{$command}) {
+		# Check an optional argument has been given.
+		if ($optarg) {
+			# The message is valid, return the event and
+			# the optional argument.
+			return "$supported_commands{$command} $optarg";
+		} else {
+			# Only return the event for the recieved command.
+			return "$supported_commands{$command}";
+		}
+	}
+
+	# If we got here, the command was not supported or something different
+	# went wrong. In such cases the function will return undef (False).
+	return undef;
+}
+
+1;
-- 
2.39.2