modules/Events.pm

   1 package Guardian::Events;
   2 use strict;
   3 use warnings;
   4
   5 use Exporter qw(import);
   6
   7 our @EXPORT_OK = qw(Init CheckAction Update);
   8
   9 # Hash which stores all supported commands from the queue.
  10 my %commands = (
  11         'count' => \&Counter,
  12         'block' => \&CallBlock,
  13         'unblock' => \&CallUnblock,
  14         'flush' => \&CallFlush,
  15 );
  16
  17 # Hash to store addresses and their current count.
  18 my %counthash = ();
  19
  20 # Hash to store all currentyl blocked addresses and a timestamp
  21 # when the block for this address can be released.
  22 my %blockhash = ();
  23
  24 # This object will contain the reference to the logger object after calling Init.
  25 my $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 #
  36 sub 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 #
  69 sub 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: $error");
  89                 return;
  90         }
  91 }
  92
  93 #
  94 ## The main "Counter" function.
  95 #
  96 ## This function is used to handle each count message + address, which has been sent by the main event
  97 ## loop of guardian.
  98 #
  99 ## It stores the address and the current count into the counthash and increase the count each time when
 100 ## the same address should be counted again. When the current count reaches the configured BlockCount,
 101 ## the responsible function will be called to block the address.
 102 #
 103 sub Counter ($@) {
 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 #
 155 sub 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 #
 185 sub 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                 # Obtain the configured FirewallAction.
 198                 my $action = $self->{FirewallAction};
 199
 200                 # Block the given address.
 201                 my $error = &DoBlock($address, $action);
 202
 203                 # If we got back an error message something went wrong.
 204                 if ($error) {
 205                         # Exit function and return the used FirewallEngine and the error message.
 206                         return "$self->{FirewallEngine} - $error";
 207                 } else {
 208                         # Address has been successfully blocked, print a log message.
 209                         $logger->Log("debug", "Address $address successfully has been blocked...");
 210                 }
 211         }
 212
 213         # Generate time when the block will expire.
 214         my $expire = time() + $self->{BlockTime};
 215
 216         # Store the blocked address and the expire time
 217         # in the blockhash.
 218         $blockhash{$address} = $expire;
 219
 220         # Return nothing "undef" if everything is okay.
 221         return undef;
 222 }
 223
 224 #
 225 ## CallUnblock function.
 226 #
 227 ## This function is responsible for unblocking and deleting a given
 228 ## address from the blockhash.
 229 #
 230 sub CallUnblock ($) {
 231         my $self = shift;
 232         my ($address, $module, $message) = @_;
 233
 234         # Log the call for unblocking an address.
 235         $logger->Log("info", "$module - $message");
 236
 237         # Return an error if no entry for the given address
 238         # is present in the blockhash.
 239         unless (exists($blockhash{$address})) {
 240                 return "Address $address was not blocked!";
 241         }
 242
 243         # Unblock the address.
 244         my $error = &DoUnblock($address);
 245
 246         # If an error message is returned, something went wrong.
 247         if ($error) {
 248                 # Exit function and return the error message.
 249                 return $error;
 250         } else {
 251                 # Address successfully has been unblocked.
 252                 $logger->Log("debug", "Address $address successfully has been unblocked...");
 253         }
 254
 255         # Drop address from blockhash.
 256         delete ($blockhash{$address});
 257
 258         # Everything worked well, return nothing.
 259         return undef;
 260 }
 261
 262 1;