guardian

   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 Thread::Queue;
  26 use Linux::Inotify2;
  27
  28 require Guardian::Parser;
  29 require Guardian::Socket;
  30
  31 # Array to store the monitored logfiles.
  32 my @monitored_files = (
  33         "/var/log/snort/alert",
  34 );
  35
  36 # Create the main queue. It is used to store and process all events which are
  37 # reported and enqueued by the worker threads.
  38 my $queue :shared = new Thread::Queue or die "Could not create new, empty queue. $!\n";;
  39
  40 # Call Init function to initzialize guardian.
  41 &Init();
  42
  43 # Infinite main loop, which processes all queued events.
  44 while(1) {
  45         # Get the amount of elements in our queue.
  46         # "undef" will be returned if it is empty.
  47         my $current_events = $queue->pending();
  48
  49         # If there is at least one element enqued
  50         if($current_events > 0) {
  51                 # Grab the data of the top enqueued event.
  52                 my $event = $queue->peek();
  53
  54                 print "Got event: $event\n";
  55
  56                 # Drop processed event from queue.
  57                 $queue->dequeue();
  58         }
  59
  60         # XXX
  61         # Temporary workaround to reduce the load of the main process.
  62         sleep(1);
  63 }
  64
  65 #
  66 ## Init function.
  67 #
  68 ## This function contains code which has to be executed while guardian
  69 ## is starting.
  70 #
  71 sub Init () {
  72         # Setup IPC mechanism via Socket in an own thread.
  73         threads->create(\&Socket);
  74
  75         # Loop through the array of which files should be monitored and
  76         # create a worker thread for each single one.
  77         foreach my $monitored_file (@monitored_files) {
  78                 # Check if the file exists and is readable.
  79                 if (-r "$monitored_file") {
  80                         # Create worker thread for the file.
  81                         threads->create(\&Worker,$monitored_file);
  82                 }
  83         }
  84 }
  85
  86 #
  87 ## Worker function.
  88 #
  89 ## This function is responsible for monitoring modifications of the given logfile,
  90 ## read them and pass them to the message parser.
  91 #
  92 ## To get file modifications the inotify subsystem of the linux kernel is used.
  93 #
  94 ## In order to prevent from permanently read and keep files opened, or dealing
  95 ## with huge logfiles, at initialization time of the worker process, the file will
  96 ## be opened once and the cursor position of the end of file (EOF) get stored. When
  97 ## reading any newly added lines from the file, we directly can jump to the last
  98 ## known position and get these lines. Afterwards, we store the current curser position
  99 ## again, so we can do it in this way over and over again.
 100 #
 101 ## All read lines get stored in an array, which will be passed to the Parser.
 102 #
 103 ## If any response (action) from the parser get recieved, it will be put into the
 104 ## shared event queue.
 105 #
 106 sub Worker ($) {
 107         my $file = @_[0];
 108
 109         # Get the fileposition.
 110         my $fileposition = &Init_fileposition("$file");
 111
 112         # Create inotify watcher.
 113         my $watcher = new Linux::Inotify2 or die "Could not use inotify. $!\n";
 114
 115         # Monitor the specified file.
 116         $watcher->watch("$file", IN_MODIFY) or die "Could not monitor $file. $!\n";
 117
 118         # Get all notifications.
 119         while ($watcher->read) {
 120                 my @message = ();
 121
 122                 # Open the file.
 123                 open (FILE, $file) or die "Could not open $file. $!\n";
 124
 125                 # Seek to the last known position.
 126                 seek (FILE, $fileposition, 0);
 127
 128                 # Get the log message.
 129                 while (my $line = <FILE>) {
 130                         # Remove any newlines.
 131                         chomp $line;
 132
 133                         # Add all lines to the message array.
 134                         push (@message, $line);
 135                 }
 136
 137                 # Update fileposition.
 138                 $fileposition = tell(FILE);
 139
 140                 # Close file.
 141                 close(FILE);
 142
 143                 # Send filename and message to the parser,
 144                 # which will return if an action has to be performed.
 145                 my @action = &Guardian::Parser::Parser("$file", @message);
 146
 147                 # Send the action to the main process and put it into
 148                 # the queue.
 149                 if (@action) {
 150                         # Lock the queue.
 151                         lock($queue);
 152
 153                         # Put the required action into the queue.
 154                         $queue->enqueue(@action);
 155                 }
 156         }
 157 }
 158
 159 #
 160 ## Socket function.
 161 #
 162 ## This function uses the Socket module to create and listen to an UNIX socket.
 163 ## It automatically accepts all incomming connections and pass the recieved
 164 ## data messages to the the Message_Parser function which is also part of the
 165 ## socket module.
 166 #
 167 ## If a valid command has been sent through the socket, the corresponding event
 168 ## will be enqueued into the shared event queue.
 169 #
 170 sub Socket () {
 171         # Create the Server socket by calling the responsible function.
 172         my $server = &Guardian::Socket::Server();
 173
 174         # Accept incomming connections from the socket.
 175         while (my $connection = $server->accept()) {
 176                 # Autoflush the socket after the data
 177                 # has been recieved.
 178                 $connection->autoflush(1);
 179
 180                 # Gather all data from the connection.
 181                 while (my $message = <$connection>) {
 182                         # Remove any newlines.
 183                         chomp($message);
 184
 185                         # Send the recieved data message to the
 186                         # socket parser.
 187                         my $action = &Guardian::Socket::Message_Parser($message);
 188
 189                         # If the parser returns to perform an action,
 190                         # add it to the main event queue.
 191                         if ($action) {
 192                                 # Lock the queue.
 193                                 lock($queue);
 194
 195                                 # Enqueue the returned action.
 196                                 $queue->enqueue($action);
 197                         }
 198                 }
 199         }
 200 }
 201
 202 #
 203 ## Function for fileposition initialization.
 204 #
 205 ## This function is used to get the cursor position of the end of file (EOF) of
 206 ## a specified file.
 207 #
 208 ## In order to prevent from permanently read and keep files opened, or dealing
 209 ## with huge logfiles, at initialization time of the worker processes, the file will
 210 ## be opened once and the cursor position of the end of file (EOF) get stored.
 211 #
 212 sub Init_fileposition ($) {
 213         my $file = $_[0];
 214
 215         # Open the file.
 216         open(FILE, $file) or die "Could not open $file. $!\n";
 217
 218         # Just seek to the end of the file (EOF).
 219         seek(FILE, 0, 2);
 220
 221         # Get and store the position.
 222         my $position = tell(FILE),
 223
 224         # Close the file again.
 225         close(FILE);
 226
 227         # Return the position.
 228         return $position;
 229 }