server_modules/dnsbl.js

   1 /**
   2  * DNS Blacklist support
   3  *
   4  * Check the client against a blacklist before connection to an IRC server
   5  */
   6
   7 var dns = require('dns'),
   8     kiwiModules = require('../server/modules');
   9
  10
  11 // The available DNS zones to check against
  12 var bl_zones = {
  13     dronebl: '.dnsbl.dronebl.org'
  14 };
  15
  16 // The DNS zone we should use
  17 var current_bl = 'dronebl';
  18
  19
  20 var module = new kiwiModules.Module('DNSBL');
  21
  22 module.on('irc connecting', function (event, event_data) {
  23     event.wait = true;
  24
  25     var client_addr = event_data.connection.state.client.websocket.handshake.real_address;
  26
  27     isBlacklisted(client_addr, function(is_blocked) {
  28         if (is_blocked) {
  29             var err = new Error('DNSBL blocked (' + client_addr + ')');
  30             err.code = 'Blacklisted';
  31
  32             event_data.connection.emit('error', err);
  33             event.preventDefault();
  34             event.callback();
  35
  36         } else {
  37             event.callback();
  38         }
  39     });
  40 });
  41
  42
  43
  44 // The actual checking against the DNS blacklist
  45 function isBlacklisted(ip, callback) {
  46     var host_lookup = reverseIp(ip) + bl_zones[current_bl];
  47
  48     dns.resolve4(host_lookup, function(err, domain) {
  49         if (err) {
  50             // Not blacklisted
  51             callback(false);
  52         } else {
  53             // It is blacklisted
  54             callback(true);
  55         }
  56     });
  57 }
  58
  59
  60 function reverseIp(ip) {
  61     return ip.split('.').reverse().join('.');
  62 }