[Core] Fix prefetch magnets missing trackers

When adding magnets that have been prefetched the tracker details were
lost. A result of returning only the lt.torrent_info.metadata which
does not contain full torrent details, such as trackers.

- Modified torrentmanager prefetch_metadata to return dict instead of
  base64 encoded bencoded metadata dict...
  - Used a namedtuple to ease identifying tuple contents.
  - Updated tests to reflect changes with mock trackers added to
    test_torrent.file.torrent.

- Refactor TorrentInfo to accept dict instead of bytes and add
  a class method to accept metadata dict with lists of trackers.
  - Rename class arg from metainfo to torrent_file, matching
    lt.torrent_info.
  - Rename metadata property to correct name; metainfo.
  - Simplify class variable naming with _filedata and _metainfo for
    torrent file contents encoded and decoded respectively.

- Update GTK Add torrent dialog to pass trackers to TorrentInfo.

6 files changed, 107 insertions, 90 deletions

diff --git a/deluge/core/core.py b/deluge/core/core.py
index 91f9b8a38..9a19e3057 100644
--- a/deluge/core/core.py
+++ b/deluge/core/core.py
@@ -437,22 +437,22 @@ class Core(component.Component):
 
     @export
     def prefetch_magnet_metadata(self, magnet, timeout=30):
-        """Download the metadata for the magnet uri without adding torrent to deluge session.
+        """Download magnet metadata without adding to Deluge session.
+
+        Used by UIs to get magnet files for selection before adding to session.
 
         Args:
             magnet (str): The magnet uri.
-            timeout (int): Time to wait to recieve metadata from peers.
+            timeout (int): Number of seconds to wait before cancelling request.
 
         Returns:
-            Deferred: A tuple of (torrent_id (str), metadata (bytes)) for the magnet.
-
-            The metadata is base64 encoded.
+            Deferred: A tuple of (torrent_id (str), metadata (dict)) for the magnet.
 
         """
 
         def on_metadata(result, result_d):
-            torrent_id, metadata = result
-            result_d.callback((torrent_id, b64encode(metadata)))
+            """Return result of torrent_id and metadata"""
+            result_d.callback(result)
             return result
 
         d = self.torrentmanager.prefetch_metadata(magnet, timeout)
diff --git a/deluge/core/torrentmanager.py b/deluge/core/torrentmanager.py
index c92939c06..a7df5012b 100644
--- a/deluge/core/torrentmanager.py
+++ b/deluge/core/torrentmanager.py
@@ -15,6 +15,7 @@ import logging
 import operator
 import os
 import time
+from collections import namedtuple
 from tempfile import gettempdir
 
 import six.moves.cPickle as pickle  # noqa: N813
@@ -339,21 +340,20 @@ class TorrentManager(component.Component):
             return torrent_info
 
     def prefetch_metadata(self, magnet, timeout):
-        """Download metadata for a magnet uri.
+        """Download the metadata for a magnet uri.
 
         Args:
             magnet (str): A magnet uri to download the metadata for.
-            timeout (int): How long
+            timeout (int): Number of seconds to wait before cancelling.
 
         Returns:
-            Deferred: A tuple of (torrent_id (str), bencoded metadata (bytes))
+            Deferred: A tuple of (torrent_id (str), metadata (dict))
 
         """
 
         torrent_id = get_magnet_info(magnet)['info_hash']
         if torrent_id in self.prefetching_metadata:
-            d = self.prefetching_metadata[torrent_id][0]
-            return d
+            return self.prefetching_metadata[torrent_id].defer
 
         add_torrent_params = {}
         add_torrent_params['save_path'] = gettempdir()
@@ -374,7 +374,8 @@ class TorrentManager(component.Component):
         # Cancel the defer if timeout reached.
         defer_timeout = self.callLater(timeout, d.cancel)
         d.addBoth(self.on_prefetch_metadata, torrent_id, defer_timeout)
-        self.prefetching_metadata[torrent_id] = (d, torrent_handle)
+        Prefetch = namedtuple('Prefetch', 'defer handle')
+        self.prefetching_metadata[torrent_id] = Prefetch(defer=d, handle=torrent_handle)
         return d
 
     def on_prefetch_metadata(self, torrent_info, torrent_id, defer_timeout):
@@ -384,18 +385,18 @@ class TorrentManager(component.Component):
         except error.AlreadyCalled:
             pass
 
-        log.debug('remove magnet from session')
+        log.debug('remove prefetch magnet from session')
         try:
-            torrent_handle = self.prefetching_metadata.pop(torrent_id)[1]
+            torrent_handle = self.prefetching_metadata.pop(torrent_id).handle
         except KeyError:
             pass
         else:
             self.session.remove_torrent(torrent_handle, 1)
 
-        metadata = b''
+        metadata = None
         if isinstance(torrent_info, lt.torrent_info):
-            log.debug('metadata received')
-            metadata = torrent_info.metadata()
+            log.debug('prefetch metadata received')
+            metadata = lt.bdecode(torrent_info.metadata())
 
         return torrent_id, metadata
 
@@ -447,8 +448,7 @@ class TorrentManager(component.Component):
             raise AddTorrentError('Torrent already being added (%s).' % torrent_id)
         elif torrent_id in self.prefetching_metadata:
             # Cancel and remove metadata fetching torrent.
-            d = self.prefetching_metadata[torrent_id][0]
-            d.cancel()
+            self.prefetching_metadata[torrent_id].defer.cancel()
 
         # Check for renamed files and if so, rename them in the torrent_info before adding.
         if options['mapped_files'] and torrent_info:
@@ -1545,7 +1545,7 @@ class TorrentManager(component.Component):
 
         # Try callback to prefetch_metadata method.
         try:
-            d = self.prefetching_metadata[torrent_id][0]
+            d = self.prefetching_metadata[torrent_id].defer
         except KeyError:
             pass
         else:
diff --git a/deluge/tests/test_core.py b/deluge/tests/test_core.py
index c0da54da5..4f64c73e6 100644
--- a/deluge/tests/test_core.py
+++ b/deluge/tests/test_core.py
@@ -314,7 +314,7 @@ class CoreTestCase(BaseTestCase):
     def test_prefetch_metadata_existing(self):
         """Check another call with same magnet returns existing deferred."""
         magnet = 'magnet:?xt=urn:btih:ab570cdd5a17ea1b61e970bb72047de141bce173'
-        expected = ('ab570cdd5a17ea1b61e970bb72047de141bce173', b'')
+        expected = ('ab570cdd5a17ea1b61e970bb72047de141bce173', None)
 
         def on_result(result):
             self.assertEqual(result, expected)
diff --git a/deluge/tests/test_torrentmanager.py b/deluge/tests/test_torrentmanager.py
index 84ad5a5e9..bf84f451b 100644
--- a/deluge/tests/test_torrentmanager.py
+++ b/deluge/tests/test_torrentmanager.py
@@ -15,7 +15,6 @@ import pytest
 from twisted.internet import defer, task
 
 from deluge import component
-from deluge.bencode import bencode
 from deluge.core.core import Core
 from deluge.core.rpcserver import RPCServer
 from deluge.error import InvalidTorrentError
@@ -72,36 +71,34 @@ class TorrentmanagerTestCase(BaseTestCase):
 
         expected = (
             'ab570cdd5a17ea1b61e970bb72047de141bce173',
-            bencode(
-                {
-                    'piece length': 32768,
-                    'sha1': (
-                        b'2\xce\xb6\xa8"\xd7\xf0\xd4\xbf\xdc^K\xba\x1bh'
-                        b'\x9d\xc5\xb7\xac\xdd'
-                    ),
-                    'name': 'azcvsupdater_2.6.2.jar',
-                    'private': 0,
-                    'pieces': (
-                        b'\xdb\x04B\x05\xc3\'\xdab\xb8su97\xa9u'
-                        b'\xca<w\\\x1ef\xd4\x9b\x16\xa9}\xc0\x9f:\xfd'
-                        b'\x97qv\x83\xa2"\xef\x9d7\x0by!\rl\xe5v\xb7'
-                        b'\x18{\xf7/"P\xe9\x8d\x01D\x9e8\xbd\x16\xe3'
-                        b'\xfb-\x9d\xaa\xbcM\x11\xba\x92\xfc\x13F\xf0'
-                        b'\x1c\x86x+\xc8\xd0S\xa9\x90`\xa1\xe4\x82\xe8'
-                        b'\xfc\x08\xf7\xe3\xe5\xf6\x85\x1c%\xe7%\n\xed'
-                        b'\xc0\x1f\xa1;\x9a\xea\xcf\x90\x0c/F>\xdf\xdagA'
-                        b'\xc42|\xda\x82\xf5\xa6b\xa1\xb8#\x80wI\xd8f'
-                        b'\xf8\xbd\xacW\xab\xc3s\xe0\xbbw\xf2K\xbe\xee'
-                        b'\xa8rG\xe1W\xe8\xb7\xc2i\xf3\xd8\xaf\x9d\xdc'
-                        b'\xd0#\xf4\xc1\x12u\xcd\x0bE?:\xe8\x9c\x1cu'
-                        b'\xabb(oj\r^\xd5\xd5A\x83\x88\x9a\xa1J\x1c?'
-                        b'\xa1\xd6\x8c\x83\x9e&'
-                    ),
-                    'length': 307949,
-                    'name.utf-8': b'azcvsupdater_2.6.2.jar',
-                    'ed2k': b'>p\xefl\xfa]\x95K\x1b^\xc2\\;;e\xb7',
-                }
-            ),
+            {
+                b'piece length': 32768,
+                b'sha1': (
+                    b'2\xce\xb6\xa8"\xd7\xf0\xd4\xbf\xdc^K\xba\x1bh'
+                    b'\x9d\xc5\xb7\xac\xdd'
+                ),
+                b'name': b'azcvsupdater_2.6.2.jar',
+                b'private': 0,
+                b'pieces': (
+                    b'\xdb\x04B\x05\xc3\'\xdab\xb8su97\xa9u'
+                    b'\xca<w\\\x1ef\xd4\x9b\x16\xa9}\xc0\x9f:\xfd'
+                    b'\x97qv\x83\xa2"\xef\x9d7\x0by!\rl\xe5v\xb7'
+                    b'\x18{\xf7/"P\xe9\x8d\x01D\x9e8\xbd\x16\xe3'
+                    b'\xfb-\x9d\xaa\xbcM\x11\xba\x92\xfc\x13F\xf0'
+                    b'\x1c\x86x+\xc8\xd0S\xa9\x90`\xa1\xe4\x82\xe8'
+                    b'\xfc\x08\xf7\xe3\xe5\xf6\x85\x1c%\xe7%\n\xed'
+                    b'\xc0\x1f\xa1;\x9a\xea\xcf\x90\x0c/F>\xdf\xdagA'
+                    b'\xc42|\xda\x82\xf5\xa6b\xa1\xb8#\x80wI\xd8f'
+                    b'\xf8\xbd\xacW\xab\xc3s\xe0\xbbw\xf2K\xbe\xee'
+                    b'\xa8rG\xe1W\xe8\xb7\xc2i\xf3\xd8\xaf\x9d\xdc'
+                    b'\xd0#\xf4\xc1\x12u\xcd\x0bE?:\xe8\x9c\x1cu'
+                    b'\xabb(oj\r^\xd5\xd5A\x83\x88\x9a\xa1J\x1c?'
+                    b'\xa1\xd6\x8c\x83\x9e&'
+                ),
+                b'length': 307949,
+                b'name.utf-8': b'azcvsupdater_2.6.2.jar',
+                b'ed2k': b'>p\xefl\xfa]\x95K\x1b^\xc2\\;;e\xb7',
+            },
         )
         self.assertEqual(expected, self.successResultOf(d))
 
@@ -109,7 +106,7 @@ class TorrentmanagerTestCase(BaseTestCase):
         magnet = 'magnet:?xt=urn:btih:ab570cdd5a17ea1b61e970bb72047de141bce173'
         d = self.tm.prefetch_metadata(magnet, 30)
         self.clock.advance(30)
-        expected = ('ab570cdd5a17ea1b61e970bb72047de141bce173', b'')
+        expected = ('ab570cdd5a17ea1b61e970bb72047de141bce173', None)
         return d.addCallback(self.assertEqual, expected)
 
     @pytest.mark.todo
diff --git a/deluge/ui/common.py b/deluge/ui/common.py
index 38c27d8cf..21bcafd5f 100644
--- a/deluge/ui/common.py
+++ b/deluge/ui/common.py
@@ -173,38 +173,36 @@ class TorrentInfo(object):
     """Collects information about a torrent file.
 
     Args:
-        filename (str): The path to the .torrent file.
+        filename (str, optional): The path to the .torrent file.
         filetree (int, optional): The version of filetree to create (defaults to 1).
-        metainfo (bytes, optional): A bencoded filedump from a .torrent file.
-        metadata (bytes, optional): A bencoded metadata info_dict.
+        torrent_file (dict, optional): A bdecoded .torrent file contents.
 
     """
 
-    def __init__(self, filename='', filetree=1, metainfo=None, metadata=None):
-        # Get the torrent metainfo from the torrent file
-        if metadata:
-            self._metainfo_dict = {b'info': bencode.bdecode(metadata)}
-
-            self._metainfo = bencode.bencode(self._metainfo_dict)
-        else:
-            self._metainfo = metainfo
-            if filename and not self._metainfo:
-                log.debug('Attempting to open %s.', filename)
-                try:
-                    with open(filename, 'rb') as _file:
-                        self._metainfo = _file.read()
-                except IOError as ex:
-                    log.warning('Unable to open %s: %s', filename, ex)
-                    return
+    def __init__(self, filename='', filetree=1, torrent_file=None):
+        self._filedata = None
+        if torrent_file:
+            self._metainfo = torrent_file
+        elif filename:
+            log.debug('Attempting to open %s.', filename)
+            try:
+                with open(filename, 'rb') as _file:
+                    self._filedata = _file.read()
+            except IOError as ex:
+                log.warning('Unable to open %s: %s', filename, ex)
+                return
 
             try:
-                self._metainfo_dict = bencode.bdecode(self._metainfo)
+                self._metainfo = bencode.bdecode(self._filedata)
             except bencode.BTFailure as ex:
                 log.warning('Failed to decode %s: %s', filename, ex)
                 return
+        else:
+            log.warning('Requires valid arguments.')
+            return
 
-        # info_dict with keys decoded.
-        info_dict = {k.decode(): v for k, v in self._metainfo_dict[b'info'].items()}
+        # info_dict with keys decoded to unicode.
+        info_dict = {k.decode(): v for k, v in self._metainfo[b'info'].items()}
         self._info_hash = sha(bencode.bencode(info_dict)).hexdigest()
 
         # Get encoding from torrent file if available
@@ -299,6 +297,25 @@ class TorrentInfo(object):
             else:
                 self._files_tree = {self._name: (0, info_dict['length'], True)}
 
+    @classmethod
+    def from_metadata(cls, metadata, trackers=None):
+        """Create a TorrentInfo from metadata and trackers
+
+        Args:
+            metadata (dict): A bdecoded info section of torrent file.
+            trackers (list of lists, optional): The trackers to include.
+
+        """
+        if not isinstance(metadata, dict):
+            return
+
+        metainfo = {b'info': metadata}
+        if trackers:
+            metainfo[b'announce'] = trackers[0][0].encode('utf-8')
+            trackers_utf8 = [[t.encode('utf-8') for t in tier] for tier in trackers]
+            metainfo[b'announce-list'] = trackers_utf8
+        return cls(torrent_file=metainfo)
+
     def as_dict(self, *keys):
         """The torrent info as a dictionary, filtered by keys.
 
@@ -358,24 +375,28 @@ class TorrentInfo(object):
         return self._files_tree
 
     @property
-    def metadata(self):
-        """The torrents metainfo dictionary.
+    def metainfo(self):
+        """Returns the torrent metainfo dictionary.
+
+        This is the bdecoded torrent file contents.
 
         Returns:
-            dict: The bdecoded metainfo dictionary.
+            dict: The metainfo dictionary.
 
         """
-        return self._metainfo_dict
+        return self._metainfo
 
     @property
     def filedata(self):
         """The contents of the .torrent file.
 
         Returns:
-            str: The metainfo bencoded dictionary from a torrent file.
+            bytes: The bencoded metainfo.
 
         """
-        return self._metainfo
+        if not self._filedata:
+            self._filedata = bencode.bencode(self._metainfo)
+        return self._filedata
 
 
 class FileTree2(object):
diff --git a/deluge/ui/gtk3/addtorrentdialog.py b/deluge/ui/gtk3/addtorrentdialog.py
index d164c2cc5..e7066f9ba 100644
--- a/deluge/ui/gtk3/addtorrentdialog.py
+++ b/deluge/ui/gtk3/addtorrentdialog.py
@@ -11,7 +11,7 @@ from __future__ import division, unicode_literals
 
 import logging
 import os
-from base64 import b64decode, b64encode
+from base64 import b64encode
 from xml.sax.saxutils import escape as xml_escape
 from xml.sax.saxutils import unescape as xml_unescape
 
@@ -251,16 +251,15 @@ class AddTorrentDialog(component.Component):
         if already_added:
             self.show_already_added_dialog(already_added)
 
-    def _on_uri_metadata(self, result, uri):
+    def _on_uri_metadata(self, result, uri, trackers):
         """Process prefetched metadata to allow file priority selection."""
-        info_hash, b64_metadata = result
-        log.debug('on_uri_metadata for %s (%s)', uri, info_hash)
+        info_hash, metadata = result
+        log.debug('magnet metadata for %s (%s)', uri, info_hash)
         if info_hash not in self.prefetching_magnets:
             return
 
-        if b64_metadata:
-            metadata = b64decode(b64_metadata)
-            info = TorrentInfo(metadata=metadata)
+        if metadata:
+            info = TorrentInfo.from_metadata(metadata, [[t] for t in trackers])
             self.files[info_hash] = info.files
             self.infos[info_hash] = info.filedata
         else:
@@ -313,7 +312,7 @@ class AddTorrentDialog(component.Component):
             self.prefetching_magnets.append(torrent_id)
             self.prefetch_waiting_message(torrent_id, None)
             d = client.core.prefetch_magnet_metadata(uri)
-            d.addCallback(self._on_uri_metadata, uri)
+            d.addCallback(self._on_uri_metadata, uri, magnet['trackers'])
             d.addErrback(self._on_uri_metadata_fail, torrent_id)
 
         if already_added: