modules/spam-detection/lib/duplicate-chat-detector.js

   1 'use strict';
   2
   3 var env = require('gitter-web-env');
   4 var config = env.config;
   5 var fs = require('fs');
   6 var path = require('path');
   7 var Promise = require('bluebird');
   8 var crypto = require('crypto');
   9 var logger = env.logger.get('spam-detection');
  10
  11 var redisClient = env.ioredis.createClient(config.get('redis_nopersist'), {
  12   keyPrefix: 'spam:'
  13 });
  14
  15 var TTL = 12 * 60 * 60;
  16
  17 function defineCommand(name, script, keys) {
  18   redisClient.defineCommand(name, {
  19     lua: fs.readFileSync(path.join(__dirname, '..', 'redis-lua', script + '.lua')),
  20     numberOfKeys: keys
  21   });
  22 }
  23
  24 defineCommand('spamDetectionCountChatForUser', 'count-chat-for-user', 1);
  25
  26 function getWarnAndBanThresholds(text) {
  27   // This should catch emojis etc
  28   if (text.length < 10) {
  29     return {
  30       warn: 80,
  31       ban: 100
  32     };
  33   }
  34
  35   if (text.length < 20) {
  36     return {
  37       warn: 16,
  38       ban: 20
  39     };
  40   }
  41
  42   return {
  43     warn: 8,
  44     ban: 10
  45   };
  46 }
  47
  48 function addHash(userId, hash, text) {
  49   var thresholds = getWarnAndBanThresholds(text);
  50
  51   return redisClient
  52     .spamDetectionCountChatForUser('dup:' + String(userId), hash, TTL)
  53     .bind({
  54       thresholds: thresholds,
  55       text: text,
  56       userId: userId
  57     })
  58     .then(function(count) {
  59       var thresholds = this.thresholds;
  60       var userId = this.userId;
  61       var text = this.text;
  62
  63       if (count > thresholds.warn) {
  64         logger.warn('User sending duplicate messages', {
  65           count: count,
  66           text: text,
  67           userId: userId
  68         });
  69       }
  70
  71       return count > thresholds.ban;
  72     });
  73 }
  74 /**
  75  * Super basic spam detection
  76  */
  77 function detect(userId, text) {
  78   var hash = crypto
  79     .createHash('md5')
  80     .update(text)
  81     .digest('hex');
  82   return addHash(userId, hash, text);
  83 }
  84
  85 module.exports = Promise.method(detect);