modules/Socket.pm

   1 package Guardian::Socket;
   2 use strict;
   3 use warnings;
   4
   5 use Exporter qw(import);
   6
   7 our @EXPORT_OK = qw(Server Client Message_Parser RemoveSocketFile);
   8
   9 use IO::Socket::UNIX qw( SOCK_STREAM SOMAXCONN );
  10
  11 # The path and filename to the UNIX socket.
  12 my $socketpath = "/run/guardian";
  13 my $socketfile = "/run/guardian/guardian.sock";
  14
  15 # Hash with all supported socket commands and events which should
  16 # be returned by the parser.
  17 my %supported_commands = (
  18         'block' => 'block',
  19         'unblock' => 'unblock',
  20         'flush' => 'flush',
  21         'reload' => 'reload',
  22         'logrotate' => 'logrotate',
  23 );
  24
  25 #
  26 ## Socket server function.
  27 #
  28 ## It is used to create the server component to provide an IPC
  29 ## mechanism for guardian.  The server function creates an UNIX
  30 ## socket.
  31 #
  32 sub Server () {
  33         # If the path for the socketfile does not exist, try to
  34         # create it.
  35         unless (-d "$socketpath") {
  36                 mkdir("$socketpath") or die "Could not create $socketpath: $!";
  37         }
  38
  39         # Delete an existing socket file.
  40         if (-e "$socketfile") {
  41                 unlink $socketfile
  42                 or die "Could not release existing socket file: $!";
  43         }
  44
  45         # Create a new UNIX socket.
  46         my $server = IO::Socket::UNIX->new(
  47                 Local => $socketfile,
  48                 Listen => SOMAXCONN,
  49                 Type => SOCK_STREAM,
  50         ) or die "Could not create socket: $!";
  51
  52         # Return the server object.
  53         return $server;
  54 }
  55
  56 #
  57 ## A client for the socket server.
  58 #
  59 ## This function provides a simple client to connect to the server socket
  60 ## and send messages through it to a running guardian process.
  61 #
  62 sub Client($) {
  63         my ($message) = @_;
  64
  65         # Create the client and connect to the server socket.
  66         my $client = IO::Socket::UNIX->new(
  67                 Type => SOCK_STREAM,
  68                 Peer => $socketfile,
  69         ) or die "Could not connect to socketfile: $!\n";
  70
  71         # Remove any newline.
  72         chomp($message);
  73
  74         # Send the message through the socket.
  75         print $client "$message\n";
  76 }
  77
  78 #
  79 ## The Socket message parser.
  80 #
  81 ## This subfunction is responsible for parsing any data or messages
  82 ## which have been recieved through the server socket.
  83 #
  84 sub Message_Parser ($) {
  85         # Splitt the message into single parts.
  86         # The first part contains the command, the second
  87         # one an optional argument.
  88         my @message = split(/ /, $_[0]);
  89         my ($command, $optarg, $unsupported) = @message;
  90
  91         # Currently only socket messages with two arguments (command and
  92         # the additional argument which is required for some commands)
  93         # are supported. If a third argument is passed, the message
  94         # is invalid and the parser returns false.
  95         if ($unsupported) {
  96                 return undef;
  97         }
  98
  99         # Check if we got a supported command.
 100         if (exists $supported_commands{$command}) {
 101                 # Check an optional argument has been given.
 102                 if ($optarg) {
 103                         # The message is valid, return the event and
 104                         # the optional argument.
 105                         return "$supported_commands{$command} $optarg";
 106                 } else {
 107                         # Only return the event for the recieved command.
 108                         return "$supported_commands{$command}";
 109                 }
 110         }
 111
 112         # If we got here, the command was not supported or something different
 113         # went wrong. In such cases the function will return undef (False).
 114         return undef;
 115 }
 116
 117 #
 118 ## RemoveSocketFile function.
 119 #
 120 ## A tiny function which just removes an existing Socket file.
 121 #
 122 sub RemoveSocketFile () {
 123         # Check if a socketfile exists.
 124         if (-e $socketfile) {
 125                 # Delete the socket file.
 126                 unlink($socketfile);
 127         }
 128 }
 129
 130 1;