Initial checkin.
[people/stevee/guardian.git] / guardian
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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
22use strict;
23use threads;
24use threads::shared;
25use Thread::Queue;
26use Linux::Inotify2;
27
28require Guardian::Parser;
29
30# Array to store the monitored logfiles.
31my @monitored_files = (
32 "/var/log/snort/alert",
33);
34
35# Create the main queue. It is used to store and process all events which are
36# reported and enqueued by the worker threads.
37my $queue :shared = new Thread::Queue or die "Could not create new, empty queue. $!\n";;
38
39# Call Init function to initzialize guardian.
40&Init();
41
42# Infinite main loop, which processes all queued events.
43while(1) {
44 # Get the amount of elements in our queue.
45 # "undef" will be returned if it is empty.
46 my $current_events = $queue->pending();
47
48 # If there is at least one element enqued
49 if($current_events > 0) {
50 # Grab the data of the top enqueued event.
51 my $event = $queue->peek();
52
53 print "Got event: $event\n";
54
55 # Drop processed event from queue.
56 $queue->dequeue();
57 }
58
59 # XXX
60 # Temporary workaround to reduce the load of the main process.
61 sleep(1);
62}
63
64#
65## Init function.
66#
67## This function contains code which has to be executed while guardian
68## is starting.
69#
70sub Init () {
71 # Loop through the array of which files should be monitored and
72 # create a worker thread for each single one.
73 foreach my $monitored_file (@monitored_files) {
74 # Check if the file exists and is readable.
75 if (-r "$monitored_file") {
76 # Create worker thread for the file.
77 threads->create(\&Worker,$monitored_file);
78 }
79 }
80}
81
82#
83## Worker function.
84#
85## This function is responsible for monitoring modifications of the given logfile,
86## read them and pass them to the message parser.
87#
88## To get file modifications the inotify subsystem of the linux kernel is used.
89#
90## In order to prevent from permanently read and keep files opened, or dealing
91## with huge logfiles, at initialization time of the worker process, the file will
92## be opened once and the cursor position of the end of file (EOF) get stored. When
93## reading any newly added lines from the file, we directly can jump to the last
94## known position and get these lines. Afterwards, we store the current curser position
95## again, so we can do it in this way over and over again.
96#
97## All read lines get stored in an array, which will be passed to the Parser.
98#
99## If any response (action) from the parser get recieved, it will be put into the
100## shared event queue.
101#
102sub Worker ($) {
103 my $file = @_[0];
104
105 # Get the fileposition.
106 my $fileposition = &Init_fileposition("$file");
107
108 # Create inotify watcher.
109 my $watcher = new Linux::Inotify2 or die "Could not use inotify. $!\n";
110
111 # Monitor the specified file.
112 $watcher->watch("$file", IN_MODIFY) or die "Could not monitor $file. $!\n";
113
114 # Get all notifications.
115 while ($watcher->read) {
116 my @message = ();
117
118 # Open the file.
119 open (FILE, $file) or die "Could not open $file. $!\n";
120
121 # Seek to the last known position.
122 seek (FILE, $fileposition, 0);
123
124 # Get the log message.
125 while (my $line = <FILE>) {
126 # Remove any newlines.
127 chomp $line;
128
129 # Add all lines to the message array.
130 push (@message, $line);
131 }
132
133 # Update fileposition.
134 $fileposition = tell(FILE);
135
136 # Close file.
137 close(FILE);
138
139 # Send filename and message to the parser,
140 # which will return if an action has to be performed.
141 my @action = &Guardian::Parser::Parser("$file", @message);
142
143 # Send the action to the main process and put it into
144 # the queue.
145 if (@action) {
146 # Lock the queue.
147 lock($queue);
148
149 # Put the required action into the queue.
150 $queue->enqueue(@action);
151 }
152 }
153}
154
155#
156## Function for fileposition initialization.
157#
158## This function is used to get the cursor position of the end of file (EOF) of
159## a specified file.
160#
161## In order to prevent from permanently read and keep files opened, or dealing
162## with huge logfiles, at initialization time of the worker processes, the file will
163## be opened once and the cursor position of the end of file (EOF) get stored.
164#
165sub Init_fileposition ($) {
166 my $file = $_[0];
167
168 # Open the file.
169 open(FILE, $file) or die "Could not open $file. $!\n";
170
171 # Just seek to the end of the file (EOF).
172 seek(FILE, 0, 2);
173
174 # Get and store the position.
175 my $position = tell(FILE),
176
177 # Close the file again.
178 close(FILE);
179
180 # Return the position.
181 return $position;
182}