modules/Parser.pm

   1 package Guardian::Parser;
   2 use strict;
   3 use warnings;
   4
   5 use Exporter qw(import);
   6
   7 our @EXPORT_OK = qw(IsSupportedParser Parser);
   8
   9 # This hash contains all supported parsers and which function
  10 # has to be called to parse messages in the right way.
  11 my %logfile_parsers = (
  12         "snort" => \&message_parser_snort,
  13 );
  14
  15 #
  16 ## The main parsing function.
  17 #
  18 ## It is used to determine which sub-parser has to be used to
  19 ## parse the given message in the right way and to return if
  20 ## any action should be performed.
  21 #
  22 sub Parser ($$) {
  23         my ($parser, @message) = @_;
  24
  25         # If no responsible message parser could be found, just return nothing.
  26         unless (exists($logfile_parsers{$parser})) {
  27                 return;
  28         }
  29
  30         # Call responsible message parser.
  31         my $action = $logfile_parsers{$parser}->(@message);
  32
  33         # Return which action should be performed.
  34         return "count $action";
  35 }
  36
  37 #
  38 ## IsSupportedParser function.
  39 #
  40 ## This very tiny function checks if a given parser name is available and
  41 ## therefore a supported parser.
  42 #
  43 ## To perform these check, the function is going to lookup if a key in the
  44 ## hash of supported parsers is available
  45 #
  46 sub IsSupportedParser ($) {
  47         my $parser = $_[0];
  48
  49         # Check if a key for the given parser exists in the hash of logfile_parsers.
  50         if(exists($logfile_parsers{$parser})) {
  51                 # Found a valid parser, so return nothing.
  52                 return 1;
  53         }
  54
  55         # Return "False" if we got here, and therefore no parser
  56         # is available.
  57         return;
  58 }
  59
  60 #
  61 ## The Snort message parser.
  62 #
  63 ## This subfunction is responsible for parsing sort alerts and determine if
  64 ## an action should be performed.
  65 #
  66 sub message_parser_snort($) {
  67         my @message = @_;
  68
  69         # XXX
  70         # Currently this parser just returns a simple message.
  71         return "$message[0] SNORT A simple Snort Message";
  72 }
  73
  74 1;