Handle invalid UTF8 data in hostblock lists

Fixes #2301

CHANGELOG.asciidoc

@@ -42,6 +42,7 @@ Fixed
 - Download suffixes like (1) are now correctly stripped with QtWebEngine
 - Crash when trying to print a tab which was closed in the meantime
 - Crash when trying to open a file twice on Windows
+- Crash when updating adblock lists with invalid UTF8-chars in them
 
 v0.10.0
 -------

qutebrowser/browser/adblock.py

@@ -58,7 +58,7 @@ def get_fileobj(byte_io):
         byte_io = zf.open(filename, mode='r')
     else:
         byte_io.seek(0)  # rewind what zipfile.is_zipfile did
-    return io.TextIOWrapper(byte_io, encoding='utf-8')
+    return byte_io
 
 
 def is_whitelisted_host(host):
@@ -147,7 +147,7 @@ class HostBlocker:
             with open(filename, 'r', encoding='utf-8') as f:
                 for line in f:
                     target.add(line.strip())
-        except OSError:
+        except (OSError, UnicodeDecodeError):
             log.misc.exception("Failed to read host blocklist!")
 
         return True
@@ -219,13 +219,27 @@ class HostBlocker:
         line_count = 0
         try:
             f = get_fileobj(byte_io)
-        except (OSError, UnicodeDecodeError, zipfile.BadZipFile,
-                zipfile.LargeZipFile, LookupError) as e:
+        except (OSError, zipfile.BadZipFile, zipfile.LargeZipFile,
+                LookupError) as e:
             message.error("adblock: Error while reading {}: {} - {}".format(
                 byte_io.name, e.__class__.__name__, e))
             return
+
         for line in f:
+            if line.startswith(b'#'):
+                # Ignoring comments early so we don't have to care about
+                # encoding errors in them.
+                continue
+
             line_count += 1
+
+            try:
+                line = line.decode('utf-8')
+            except UnicodeDecodeError:
+                log.misc.error("Failed to decode: {!r}".format(line))
+                error_count += 1
+                continue
+
             # Remove comments
             try:
                 hash_idx = line.index('#')
@@ -245,9 +259,11 @@ class HostBlocker:
                 host = parts[1]
             else:
                 error_count += 1
+                log.misc.error("Failed to parse: {!r}".format(line))
                 continue
             if host not in self.WHITELISTED:
                 self._blocked_hosts.add(host)
+
         log.misc.debug("{}: read {} lines".format(byte_io.name, line_count))
         if error_count > 0:
             message.error("adblock: {} read errors for {}".format(

tests/unit/browser/test_adblock.py

@@ -312,6 +312,68 @@ def test_failed_dl_update(config_stub, basedir, download_stub,
     assert_urls(host_blocker, whitelisted=[])
 
 
+@pytest.mark.parametrize('location', ['content', 'comment'])
+def test_invalid_utf8(config_stub, download_stub, tmpdir, caplog, location):
+    """Make sure invalid UTF-8 is handled correctly.
+
+    See https://github.com/qutebrowser/qutebrowser/issues/2301
+    """
+    blocklist = tmpdir / 'blocklist'
+    if location == 'comment':
+        blocklist.write_binary(b'# nbsp: \xa0\n')
+    else:
+        assert location == 'content'
+        blocklist.write_binary(b'https://www.example.org/\xa0')
+    for url in BLOCKLIST_HOSTS:
+        blocklist.write(url + '\n', mode='a')
+
+    config_stub.data = {
+        'content': {
+            'host-block-lists': [QUrl(str(blocklist))],
+            'host-blocking-enabled': True,
+            'host-blocking-whitelist': None,
+        }
+    }
+    host_blocker = adblock.HostBlocker()
+    host_blocker.adblock_update()
+    finished_signal = host_blocker._in_progress[0].finished
+
+    if location == 'content':
+        with caplog.at_level(logging.ERROR):
+            finished_signal.emit()
+        expected = (r"Failed to decode: "
+                    r"b'https://www.example.org/\xa0localhost\n'")
+        assert caplog.records[-2].message == expected
+    else:
+        finished_signal.emit()
+
+    host_blocker.read_hosts()
+    assert_urls(host_blocker, whitelisted=[])
+
+
+def test_invalid_utf8_compiled(config_stub, tmpdir, monkeypatch, caplog):
+    """Make sure invalid UTF-8 in the compiled file is handled."""
+    data_dir = tmpdir / 'data'
+    config_dir = tmpdir / 'config'
+    monkeypatch.setattr(adblock.standarddir, 'data', lambda: data_dir)
+    monkeypatch.setattr(adblock.standarddir, 'config', lambda: config_dir)
+
+    config_stub.data = {
+        'content': {
+            'host-block-lists': [],
+        }
+    }
+
+    (config_dir / 'blocked-hosts').write_binary(
+        b'https://www.example.org/\xa0')
+    (data_dir / 'blocked-hosts').ensure()
+
+    host_blocker = adblock.HostBlocker()
+    with caplog.at_level(logging.ERROR):
+        host_blocker.read_hosts()
+    assert caplog.records[-1].message == "Failed to read host blocklist!"
+
+
 def test_blocking_with_whitelist(config_stub, basedir, download_stub,
                                  data_tmpdir, tmpdir):
     """Ensure hosts in host-blocking-whitelist are never blocked."""