adds seeders retrieval from magnetlink

lib/torrent.js

@@ -1,13 +1,37 @@
 const torrentStream = require('torrent-stream');
 const needle = require('needle');
 const parseTorrent = require('parse-torrent');
+const async = require('async');
+const decode = require('magnet-uri');
 const { retrieveTorrentFiles } = require('./cache');
 
 const MAX_PEER_CONNECTIONS = process.env.MAX_PEER_CONNECTIONS || 20;
+const SEEDS_CHECK_TIMEOUT = process.env.SEEDS_CHECK_TIMEOUT || 10 * 1000; // 10 secs
 const EXTENSIONS = ["3g2", "3gp", "avi", "flv", "mkv", "mov", "mp2", "mp4", "mpe", "mpeg", "mpg", "mpv", "webm", "wmv"];
 
 module.exports.updateCurrentSeeders = function (torrent) {
-  return Promise.resolve({ ...torrent, seeders: torrent.seeders || 0 });
+  return new Promise((resolve) => {
+    if (!torrent.magnetLink) {
+      return resolve(0);
+    }
+    const Tracker = require("peer-search/tracker");
+
+    const seeders = {};
+    const decodedMagnetLink = decode(torrent.magnetLink);
+    const trackers = decodedMagnetLink && decodedMagnetLink.tr;
+    const callback = () => resolve(Math.max(...Object.values(seeders).map(values => values[0]).concat(0)));
+    setTimeout(callback, SEEDS_CHECK_TIMEOUT);
+
+    async.each(trackers, function (tracker, ready) {
+      const t = new Tracker(tracker, {}, torrent.infoHash);
+      console.error = () => 0; // do nothing
+      t.run();
+      t.on("info", function (inf) {
+        seeders[tracker] = [inf.seeders, inf.leechers];
+        ready();
+      });
+    }, callback);
+  }).then((seeders) => ({ ...torrent, seeders: torrent.seeders || seeders }));
 };
 
 module.exports.torrentFiles = function (torrent) {

package.json

@@ -33,6 +33,7 @@
     "parse-torrent": "^6.1.2",
     "parse-torrent-title": "git://github.com/TheBeastLT/parse-torrent-title.git#master",
     "peer-search": "^0.6.x",
+    "async": "0.9.2",
     "pg": "^7.8.2",
     "pg-hstore": "^2.3.2",
     "sequelize": "^4.43.0",