Introduce "Events" module
[people/stevee/guardian.git] / modules / Events.pm
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1package Guardian::Events;
2use strict;
3use warnings;
4
5use Exporter qw(import);
6
7our @EXPORT_OK = qw(Init CheckAction Update);
8
9# Hash which stores all supported commands from the queue.
10my %commands = (
11 'count' => \&Counter,
12 'block' => \&CallBlock,
13 'unblock' => \&CallUnblock,
14 'flush' => \&CallFlush,
15);
16
17# Hash to store addresses and their current count.
18my %counthash = ();
19
20# Hash to store all currentyl blocked addresses and a timestamp
21# when the block for this address can be released.
22my %blockhash = ();
23
24# This object will contain the reference to the logger object after calling Init.
25my $logger;
26
27#
28## The "Init" (Block) function.
29#
30## This function is responsible to initialize Block as a class based object.
31## It has to be called once before any blocking event can be processed.
32#
33## The following arguments must be passed, during initialization:
34## "BlockCount" and "BlockTime" which both have to be natural numbers.
35#
36sub Init (%) {
37 my ( $class, %args ) = @_;
38 my $self = \%args;
39
40 # Fail, if some critical arguments are missing.
41 unless ((exists($self->{BlockCount})) && (exists($self->{BlockTime}))) {
42 die "Could not initialize Block: Too less arguments are given.\n";
43 }
44
45 # Use bless to make "$self" to an object of class "$class".
46 bless($self, $class);
47
48 # Assign logger object.
49 $logger = $self->{Logger};
50
51 # Log used firewall engine.
52 $logger->Log("debug", "Using firewall engine: $self->{FirewallEngine}");
53
54 # Try to load the specified firewall engine or die.
55 my $module_name = "Guardian::" . $self->{FirewallEngine};
56 eval "use $module_name; 1" or die "Could not load a module for firewall engine: $self->{FirewallEngine}!";
57
58 # Return the class object.
59 return $self;
60}
61
62#
63## The main "CheckAction" function.
64#
65## This function is used to handle each recived event from the main event queue of guardian.
66#
67## It will check if the given command is valid and will pass it to the responsible function.
68#
69sub CheckAction ($$) {
70 my $self = shift;
71 my @event = split(/ /, $_[0], 4);
72 my ($command, $address, $module, $message) = @event;
73
74 # Check if we got an invalid command.
75 unless(exists($commands{$command})) {
76 $logger->Log("err", "The CheckAction function has been called with an unsupported command ($command)!");
77 return;
78 }
79
80 # XXX
81 # Check if the given address is valid.
82
83 # Call required handler.
84 my $error = $commands{$command}->($self, $address, $module, $message);
85
86 # If we got any return code, something went wrong and should be logged.
87 if ($error) {
88 $logger->Log("err", "Got error: $error");
89 return;
90 }
91}
92
93#
94## The main "Counter" function.
95#
96## This function is used to handle each count message + address, which has been sent by the main event
97## loop of guardian.
98#
99## It stores the address and the current count into the counthash and increase the count each time when
100## the same address should be counted again. When the current count reaches the configured BlockCount,
101## the responsible function will be called to block the address.
102#
103sub Counter ($@) {
104 my $self = shift;
105 my ($address, $module, $message) = @_;
106
107 # Log event.
108 $logger->Log("debug", "$module reported $message for address: $address");
109
110 # Increase existing count or start counting for new source addresses.
111 if (exists($counthash{$address})) {
112 # Skip already blocked addresses.
113 if (exists($blockhash{$address})) {
114 return undef;
115 }
116
117 # Increase count of the existing entry.
118 $counthash{$address} = $counthash{$address} + 1;
119
120 # Log altered count of the address.
121 $logger->Log("debug", "Source $address now has count $counthash{$address}/$self->{BlockCount}...");
122 } else {
123 # Log that counting for the address has been started.
124 $logger->Log("debug", "Start counting for $address...");
125
126 # Set count to "1".
127 $counthash{$address} = 1;
128 }
129
130 # Check if the address has reached the configured count limit.
131 if ($counthash{$address} >= $self->{BlockCount}) {
132 # Write out log message.
133 $logger->Log("info", "Blocking $address for $self->{BlockTime} seconds...");
134
135 # Call block subroutine to block the address.
136 my $error = &CallBlock($self, $address, $module, $message);
137
138 # Return the message if an error occurs.
139 return $error;
140 }
141
142 # Everything worked well, return nothing.
143 return undef;
144}
145
146#
147## The RemoveBlocks function.
148#
149## This function periodly will be called and is responsible for releasing the block if the Blocktime
150## on an address has expired.
151#
152## To do this, the code will loop through all entries of the blockhash and check
153## if the estimiated BlockTime of each address has reached and so the block can be released.
154#
155sub RemoveBlocks () {
156 my $self = shift;
157
158 # Get the current time.
159 my $time = time();
160
161 # Loop through the blockhash.
162 foreach my $address (keys %blockhash) {
163 # Check if the blocktime for the address has expired.
164 if ($blockhash{$address} <= $time) {
165 # Call unblock subroutine.
166 my $error = &CallUnblock($self, $address, "BlockTime", "has expired for $address");
167
168 # Log error messages if returned.
169 if ($error) {
170 $logger->Log("err", "$error");
171 }
172 }
173 }
174
175 # Everything okay, return nothing.
176 return undef;
177}
178
179#
180## The CallBlock function.
181#
182## This function is called, if the BlockCount for an address is reached or a direct
183## request for blocking an address has been recieved.
184#
185sub CallBlock ($@) {
186 my $self = shift;
187 my ($address, $module, $message) = @_;
188
189 # Log the call for blocking an address.
190 $logger->Log("info", "$module - $message");
191
192 # Check if an entry for this address exists
193 # in the blockhash. If not, the address has
194 # not been blocked yet, call the responisible
195 # function to do this now.
196 unless (exists($blockhash{$address})) {
197 # XXX
198 # Add posibility to use a configure-able action.
199 my $action;
200
201 # Block the given address.
202 my $error = &DoBlock($address, $action);
203
204 # If we got back an error message something went wrong.
205 if ($error) {
206 # Exit function and return the error message.
207 return $error;
208 } else {
209 # Address has been successfully blocked, print a log message.
210 $logger->Log("debug", "Address $address successfully has been blocked...");
211 }
212 }
213
214 # Generate time when the block will expire.
215 my $expire = time() + $self->{BlockTime};
216
217 # Store the blocked address and the expire time
218 # in the blockhash.
219 $blockhash{$address} = $expire;
220
221 # Return nothing "undef" if everything is okay.
222 return undef;
223}
224
225#
226## CallUnblock function.
227#
228## This function is responsible for unblocking and deleting a given
229## address from the blockhash.
230#
231sub CallUnblock ($) {
232 my $self = shift;
233 my ($address, $module, $message) = @_;
234
235 # Log the call for unblocking an address.
236 $logger->Log("info", "$module - $message");
237
238 # Return an error if no entry for the given address
239 # is present in the blockhash.
240 unless (exists($blockhash{$address})) {
241 return "Address $address was not blocked!";
242 }
243
244 # Unblock the address.
245 my $error = &DoUnblock($address);
246
247 # If an error message is returned, something went wrong.
248 if ($error) {
249 # Exit function and return the error message.
250 return $error;
251 } else {
252 # Address successfully has been unblocked.
253 $logger->Log("debug", "Address $address successfully has been unblocked...");
254 }
255
256 # Drop address from blockhash.
257 delete ($blockhash{$address});
258
259 # Everything worked well, return nothing.
260 return undef;
261}
262
2631;