Support http torrent urls with redirects

Fixes #176

1 files changed, 36 insertions, 6 deletions

diff --git a/lib/torrent.js b/lib/torrent.js
index 7659314..28d3603 100644
--- a/lib/torrent.js
+++ b/lib/torrent.js
@@ -8,6 +8,7 @@ var EventEmitter = require('events').EventEmitter
 var fs = require('fs') // browser exclude
 var hh = require('http-https') // browser exclude
 var inherits = require('inherits')
+var once = require('once')
 var parallel = require('run-parallel')
 var parseTorrent = require('parse-torrent')
 var RarityMap = require('./rarity-map')
@@ -15,6 +16,7 @@ var reemit = require('re-emitter')
 var Server = require('./server') // browser exclude
 var Storage = require('./storage')
 var Swarm = require('bittorrent-swarm') // `webtorrent-swarm` in browser
+var url = require('url')
 var ut_metadata = require('ut_metadata')
 var ut_pex = require('ut_pex') // browser exclude
 
@@ -75,12 +77,10 @@ function Torrent (torrentId, opts) {
 
   } else if (typeof hh.get === 'function' && /^https?:/.test(torrentId)) {
     // http or https url to torrent file
-    hh.get(torrentId, function (res) {
-      res.pipe(concat(function (torrent) {
-        onTorrentId(torrent)
-      }))
-    }).on('error', function (err) {
-      self.emit('error', new Error('error downloading torrent: ' + err.message))
+    httpGet(torrentId, function (err, torrent) {
+      if (err)
+        return self.emit('error', new Error('error downloading torrent: ' + err.message))
+      onTorrentId(torrent)
     })
 
   } else if (typeof fs.readFile === 'function') {
@@ -997,3 +997,33 @@ function randomizedForEach (array, cb) {
     cb(array[index], index, array)
   })
 }
+
+/**
+ * Make http or https request, following redirects.
+ * @param {string} u
+ * @param {function}
+ * @param {number=} maxRedirects
+ * @return {http.ClientRequest}
+ */
+function httpGet (u, cb, maxRedirects) {
+  cb = once(cb)
+  if (!maxRedirects) maxRedirects = 5
+  if (maxRedirects === 0) return cb(new Error('too many redirects'))
+
+  hh.get(u, function (res) {
+    // Check for redirect
+    if (res.statusCode >= 300 && res.statusCode < 400 && 'location' in res.headers) {
+      var location = res.headers.location
+      if (!url.parse(location).host) {
+        // If relative redirect, prepend host of current url
+        var parsed = url.parse(u)
+        location = parsed.protocol + '//' + parsed.host + location
+      }
+      res.resume() // discard response
+      return httpGet(location, cb, --maxRedirects)
+    }
+    res.pipe(concat(function (data) {
+      cb(null, data)
+    }))
+  }).on('error', cb)
+}