Fix parsing magnet with tracker tiers

Magnets with trackers specified with tr.x param were not being unquoted
so unusable raw tracker string was being set.

Fixed by unquoting tracker and adding test

See-also: https://dev.deluge-torrent.org/ticket/2716

deluge/common.py

@@ -734,6 +734,8 @@ MAGNET_SCHEME = 'magnet:?'
 XT_BTIH_PARAM = 'xt=urn:btih:'
 DN_PARAM = 'dn='
 TR_PARAM = 'tr='
+TR_TIER_PARAM = 'tr.'
+TR_TIER_REGEX = re.compile(r'^tr.(\d+)=(\S+)')
 
 
 def is_magnet(uri):
@@ -776,8 +778,6 @@ def get_magnet_info(uri):
 
     """
 
-    tr0_param = 'tr.'
-    tr0_param_regex = re.compile(r'^tr.(\d+)=(\S+)')
     if not uri.startswith(MAGNET_SCHEME):
         return {}
 
@@ -805,12 +805,14 @@ def get_magnet_info(uri):
             tracker = unquote_plus(param[len(TR_PARAM) :])
             trackers[tracker] = tier
             tier += 1
-        elif param.startswith(tr0_param):
-            try:
-                tier, tracker = re.match(tr0_param_regex, param).groups()
-                trackers[tracker] = tier
-            except AttributeError:
-                pass
+        elif param.startswith(TR_TIER_PARAM):
+            tracker_match = re.match(TR_TIER_REGEX, param)
+            if not tracker_match:
+                continue
+
+            tier, tracker = tracker_match.groups()
+            tracker = unquote_plus(tracker)
+            trackers[tracker] = int(tier)
 
     if info_hash:
         if not name:

deluge/tests/test_common.py

@@ -7,6 +7,7 @@
 import os
 import sys
 import tarfile
+from urllib.parse import quote_plus
 
 import pytest
 
@@ -19,6 +20,7 @@ from deluge.common import (
     fsize,
     fspeed,
     ftime,
+    get_magnet_info,
     get_path_size,
     is_infohash,
     is_interface,
@@ -209,3 +211,16 @@ class TestCommon:
                 if tar_info.name == 'archive_message.txt':
                     result = tar.extractfile(tar_info).read().decode()
                     assert result == 'test'
+
+    def test_get_magnet_info_tiers(self):
+        tracker1 = 'udp://tracker1.example.com'
+        tracker2 = 'udp://tracker2.example.com'
+        magnet = (
+            'magnet:?xt=urn:btih:SU5225URMTUEQLDXQWRB2EQWN6KLTYKN'
+            f'&tr.1={quote_plus(tracker1)}'
+            f'&tr.2={quote_plus(tracker2)}'
+        )
+        result = get_magnet_info(magnet)
+        assert result['info_hash'] == '953bad769164e8482c7785a21d12166f94b9e14d'
+        assert result['trackers'][tracker1] == 1
+        assert result['trackers'][tracker2] == 2