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 # Hash to store user-defined IP addresses and/or subnets which should be
  25 # ignored in case any events should be repored for them.
  26 my %ignorehash = ();
  27
  28 # This object will contain the reference to the logger object after calling Init.
  29 my $logger;
  30
  31 #
  32 ## The "Init" (Block) function.
  33 #
  34 ## This function is responsible to initialize Block as a class based object.
  35 ## It has to be called once before any blocking event can be processed.
  36 #
  37 ## The following arguments must be passed, during initialization:
  38 ## "BlockCount" and "BlockTime" which both have to be natural numbers.
  39 #
  40 sub Init (%) {
  41         my ( $class, %args ) = @_;
  42         my $self = \%args;
  43
  44         # Fail, if some critical arguments are missing.
  45         unless ((exists($self->{BlockCount})) && (exists($self->{BlockTime}))) {
  46                 die "Could not initialize Block: Too less arguments are given.\n";
  47         }
  48
  49         # Use bless to make "$self" to an object of class "$class".
  50         bless($self, $class);
  51
  52         # Assign logger object.
  53         $logger = $self->{Logger};
  54
  55         # Log used firewall engine.
  56         $logger->Log("debug", "Using firewall engine: $self->{FirewallEngine}");
  57
  58         # Try to load the specified firewall engine or die.
  59         my $module_name = "Guardian::" . $self->{FirewallEngine};
  60         eval "use $module_name; 1" or die "Could not load a module for firewall engine: $self->{FirewallEngine}!";
  61
  62         # Check if an IgnoreFile has been configured.
  63         if (exists($self->{IgnoreFile})) {
  64                 # Call function to handle the ignore mechanism.
  65                 &GenerateIgnoreList($self->{IgnoreFile});
  66         }
  67
  68         # Return the class object.
  69         return $self;
  70 }
  71
  72 #
  73 ## The main "CheckAction" function.
  74 #
  75 ## This function is used to handle each recived event from the main event queue of guardian.
  76 #
  77 ## It will check if the given command is valid and will pass it to the responsible function.
  78 #
  79 sub CheckAction ($$) {
  80         my $self = shift;
  81         my @event = split(/ /, $_[0], 4);
  82         my ($command, $address, $module, $message) = @event;
  83
  84         # Check if we got an invalid command.
  85         unless(exists($commands{$command})) {
  86                 $logger->Log("err", "The CheckAction function has been called with an unsupported command ($command)!");
  87                 return;
  88         }
  89
  90         # Convert and validate the given address.
  91         my $bin_address = &Guardian::Base::IPOrNet2Int($address);
  92
  93         # Abort if the given address could not be converted because it is not valid.
  94         unless ($bin_address) {
  95                 $logger->Log("err", "Invalid IP address: $address");
  96                 return;
  97         }
  98
  99         # Check if address should be ignored.
 100         if(&_IsOnIgnoreList($bin_address)) {
 101                 # Log message.
 102                 $logger->Log("info", "Ignoring event for $address, because it is part of the ignore list.");
 103                 return;
 104         }
 105
 106         # Call required handler.
 107         my $error = $commands{$command}->($self, $address, $module, $message);
 108
 109         # If we got any return code, something went wrong and should be logged.
 110         if ($error) {
 111                 $logger->Log("err", "Got error: $error");
 112                 return;
 113         }
 114 }
 115
 116 #
 117 ## The main "Counter" function.
 118 #
 119 ## This function is used to handle each count message + address, which has been sent by the main event
 120 ## loop of guardian.
 121 #
 122 ## It stores the address and the current count into the counthash and increase the count each time when
 123 ## the same address should be counted again. When the current count reaches the configured BlockCount,
 124 ## the responsible function will be called to block the address.
 125 #
 126 sub Counter ($@) {
 127         my $self = shift;
 128         my ($address, $module, $message) = @_;
 129
 130         # Log event.
 131         $logger->Log("debug", "$module reported $message for address: $address");
 132
 133         # Increase existing count or start counting for new source addresses.
 134         if (exists($counthash{$address})) {
 135                 # Skip already blocked addresses.
 136                 if (exists($blockhash{$address})) {
 137                         return undef;
 138                 }
 139
 140                 # Increase count of the existing entry.
 141                 $counthash{$address} = $counthash{$address} + 1;
 142
 143                 # Log altered count of the address.
 144                 $logger->Log("debug", "Source $address now has count $counthash{$address}/$self->{BlockCount}...");
 145         } else {
 146                 # Log that counting for the address has been started.
 147                 $logger->Log("debug", "Start counting for $address...");
 148
 149                 # Set count to "1".
 150                 $counthash{$address} = 1;
 151         }
 152
 153         # Check if the address has reached the configured count limit.
 154         if ($counthash{$address} >= $self->{BlockCount}) {
 155                 # Write out log message.
 156                 $logger->Log("info", "Blocking $address for $self->{BlockTime} seconds...");
 157
 158                 # Call block subroutine to block the address.
 159                 my $error = &CallBlock($self, $address, $module, $message);
 160
 161                 # Return the message if an error occurs.
 162                 return $error;
 163         }
 164
 165         # Everything worked well, return nothing.
 166         return undef;
 167 }
 168
 169 #
 170 ## The RemoveBlocks function.
 171 #
 172 ## This function periodly will be called and is responsible for releasing the block if the Blocktime
 173 ## on an address has expired.
 174 #
 175 ## To do this, the code will loop through all entries of the blockhash and check
 176 ## if the estimiated BlockTime of each address has reached and so the block can be released.
 177 #
 178 sub RemoveBlocks () {
 179         my $self = shift;
 180
 181         # Get the current time.
 182         my $time = time();
 183
 184         # Loop through the blockhash.
 185         foreach my $address (keys %blockhash) {
 186                 # Check if the blocktime for the address has expired.
 187                 if ($blockhash{$address} <= $time) {
 188                         # Call unblock subroutine.
 189                         my $error = &CallUnblock($self, $address, "BlockTime", "has expired for $address");
 190
 191                         # Log error messages if returned.
 192                         if ($error) {
 193                                 $logger->Log("err", "$error");
 194                         }
 195                 }
 196         }
 197
 198         # Everything okay, return nothing.
 199         return undef;
 200 }
 201
 202 #
 203 ## The CallBlock function.
 204 #
 205 ## This function is called, if the BlockCount for an address is reached or a direct
 206 ## request for blocking an address has been recieved.
 207 #
 208 sub CallBlock ($@) {
 209         my $self = shift;
 210         my ($address, $module, $message) = @_;
 211
 212         # Log the call for blocking an address.
 213         $logger->Log("info", "$module - $message");
 214
 215         # Check if an entry for this address exists
 216         # in the blockhash. If not, the address has
 217         # not been blocked yet, call the responisible
 218         # function to do this now.
 219         unless (exists($blockhash{$address})) {
 220                 # Obtain the configured FirewallAction.
 221                 my $action = $self->{FirewallAction};
 222
 223                 # Block the given address.
 224                 my $error = &DoBlock($address, $action);
 225
 226                 # If we got back an error message something went wrong.
 227                 if ($error) {
 228                         # Exit function and return the used FirewallEngine and the error message.
 229                         return "$self->{FirewallEngine} - $error";
 230                 } else {
 231                         # Address has been successfully blocked, print a log message.
 232                         $logger->Log("debug", "Address $address successfully has been blocked...");
 233                 }
 234         }
 235
 236         # Generate time when the block will expire.
 237         my $expire = time() + $self->{BlockTime};
 238
 239         # Store the blocked address and the expire time
 240         # in the blockhash.
 241         $blockhash{$address} = $expire;
 242
 243         # Return nothing "undef" if everything is okay.
 244         return undef;
 245 }
 246
 247 #
 248 ## CallUnblock function.
 249 #
 250 ## This function is responsible for unblocking and deleting a given
 251 ## address from the blockhash.
 252 #
 253 sub CallUnblock ($) {
 254         my $self = shift;
 255         my ($address, $module, $message) = @_;
 256
 257         # Log the call for unblocking an address.
 258         $logger->Log("info", "$module - $message");
 259
 260         # Return an error if no entry for the given address
 261         # is present in the blockhash.
 262         unless (exists($blockhash{$address})) {
 263                 return "Address $address was not blocked!";
 264         }
 265
 266         # Unblock the address.
 267         my $error = &DoUnblock($address);
 268
 269         # If an error message is returned, something went wrong.
 270         if ($error) {
 271                 # Exit function and return the error message.
 272                 return $error;
 273         } else {
 274                 # Address successfully has been unblocked.
 275                 $logger->Log("debug", "Address $address successfully has been unblocked...");
 276         }
 277
 278         # Drop address from blockhash.
 279         delete ($blockhash{$address});
 280
 281         # Everything worked well, return nothing.
 282         return undef;
 283 }
 284
 285 #
 286 ## GenerateIgnoreList function.
 287 #
 288 ## This function is responsible for generating/updating the
 289 ## IgnoreHash which contains all ignored IP addresses and
 290 ## networks.
 291 #
 292 sub GenerateIgnoreList($) {
 293         my $file = shift;
 294
 295         # Check if the given IgnoreFile could be opened.
 296         unless(-e $file) {
 297                 $logger->Log("err", "The configured IgnoreFile \($file\) could not be opened. Skipped!");
 298                 return;
 299         }
 300
 301         # Open the given IgnoreFile.
 302         open (IGNORE, $file);
 303
 304         # Read-in the file line by line.
 305         while (<IGNORE>) {
 306                 # Skip comments.
 307                 next if (/\#/);
 308
 309                 # Skip blank lines.
 310                 next if (/^\s*$/);
 311
 312                 # Remove any newlines.
 313                 chomp;
 314
 315                 # Check if the line contains a valid single address or network and
 316                 # convert it into binary format. Store the result/start and
 317                 # end values in a temporary array.
 318                 my @values = &Guardian::Base::IPOrNet2Int($_);
 319
 320                 # If the function returned any values, the line contained a valid
 321                 # single address or network which successfully has been converted into
 322                 # binary format.
 323                 if (@values) {
 324                         # Assign the array as value to the ignorehash.
 325                         $ignorehash{$_} = [@values];
 326                 } else {
 327                         # Log invalid entry.
 328                         $logger->Log("err", "IgnoreFile contains an invalid address/network: $_");
 329
 330                         # Skip line.
 331                         next;
 332                 }
 333         }
 334
 335         # Close filehandle for the IgnoreFile.
 336         close (IGNORE);
 337 }
 338
 339 #
 340 ## Private function to check if an address is part of the Ignore Hash.
 341 #
 342 ## This function requires
 343 #
 344 sub _IsOnIgnoreList ($) {
 345         my $bin_address = shift;
 346
 347         # Loop through the ignore hash and grab the stored values.
 348         foreach my $key ( keys %ignorehash ) {
 349                 # Dereference values array.
 350                 my @values = @{$ignorehash{$key}};
 351
 352                 # Obtain amount of items for the current value array.
 353                 my $items = scalar @values;
 354
 355                 # Whether the amount equals one, the given binary address just
 356                 # needs to be compared against a single address.
 357                 if ($items eq "1") {
 358                         my ($ignored_address) = @values;
 359
 360                         # Simple check if the stored and the given binary address
 361                         # are the same.
 362                         if ($bin_address eq $ignored_address) {
 363                                 # The given address is part of the ignore list.
 364                                 $logger->Log("debug", "Address $key found on the ignore list.");
 365
 366                                 # Return "1" (True).
 367                                 return 1;
 368                         }
 369                 }
 370
 371                 # If the amount equals two, for passed binary address needs to
 372                 # be checked if it is part of the ignored network range.
 373                 elsif ($items eq "2") {
 374                         my ($first_address, $last_address) = @values;
 375
 376                         # Check if the passed binary address is bigger than
 377                         # the first address and smaler than the last address
 378                         # (between) the stored network range.
 379                         if (($bin_address >= $first_address) && ($bin_address <= $last_address)) {
 380                                 # The address is part of an ignored network.
 381                                 $logger->Log("debug", "Address is found inside the ignored network $key.");
 382
 383                                 # Return "1" (True).
 384                                 return 1;
 385                         }
 386
 387                 # If the amount is not eighter one or two, the current entry of the ignorehash seems
 388                 # to be corrupted. Skip and log it.
 389                 } else {
 390                         # Write log message about this corruped item in the ignore hash.
 391                         $logger->Log("err", "Invalid item in the Ignore Hash: $key - @values");
 392
 393                         # Skip this element of the ignore hash.
 394                         next;
 395                 }
 396         }
 397
 398         # If we got here, the given address is not part of the ignore hash.
 399         # Return nothing (False).
 400         return;
 401 }
 402
 403 1;