Protect cache_exitnodes_to_disk from raising OSErrors

src/tribler/core/components/tunnel/community/tunnel_community.py

@@ -6,10 +6,9 @@
 from binascii import unhexlify
 from collections import Counter
 from distutils.version import LooseVersion
-from typing import List
+from typing import List, Optional
 
 import async_timeout
-
 from ipv8.messaging.anonymization.caches import CreateRequestCache
 from ipv8.messaging.anonymization.community import unpack_cell
 from ipv8.messaging.anonymization.hidden_services import HiddenTunnelCommunity
@@ -48,6 +47,7 @@
     RelayBalanceResponsePayload,
 )
 from tribler.core.utilities.bencodecheck import is_bencoded
+from tribler.core.utilities.path_util import Path
 from tribler.core.utilities.simpledefs import (
     DLSTATUS_DOWNLOADING,
     DLSTATUS_METADATA,
@@ -72,7 +72,7 @@ class TriblerTunnelCommunity(HiddenTunnelCommunity):
 
     def __init__(self, *args, **kwargs):
         self.bandwidth_community = kwargs.pop('bandwidth_community', None)
-        self.exitnode_cache = kwargs.pop('exitnode_cache', None)
+        self.exitnode_cache: Optional[Path] = kwargs.pop('exitnode_cache', None)
         self.config = kwargs.pop('config', None)
         self.notifier = kwargs.pop('notifier', None)
         self.dlmgr = kwargs.pop('dlmgr', None)
@@ -140,9 +140,12 @@ def cache_exitnodes_to_disk(self):
         exit_nodes = Network()
         for peer in self.get_candidates(PEER_FLAG_EXIT_BT):
             exit_nodes.add_verified_peer(peer)
-        self.logger.debug('Writing exit nodes to cache: %s', self.exitnode_cache)
-        with open(self.exitnode_cache, 'wb') as cache:
-            cache.write(exit_nodes.snapshot())
+        snapshot = exit_nodes.snapshot()
+        self.logger.info(f'Writing exit nodes to cache file: {self.exitnode_cache}')
+        try:
+            self.exitnode_cache.write_bytes(snapshot)
+        except OSError as e:
+            self.logger.warning(f'{e.__class__.__name__}: {e}')
 
     def restore_exitnodes_from_disk(self):
         """
@@ -601,7 +604,7 @@ async def on_http_request(self, source_address, payload, circuit_id):
                     response += line
                     if not line.strip():
                         # Read HTTP response body (1MB max)
-                        response += await reader.read(1024**2)
+                        response += await reader.read(1024 ** 2)
                         break
         except OSError:
             self.logger.warning('Tunnel HTTP request failed')
@@ -624,7 +627,7 @@ async def on_http_request(self, source_address, payload, circuit_id):
         for i in range(num_cells):
             self.send_cell(source_address,
                            HTTPResponsePayload(circuit_id, payload.identifier, i, num_cells,
-                                               response[i*MAX_HTTP_PACKET_SIZE:(i+1)*MAX_HTTP_PACKET_SIZE]))
+                                               response[i * MAX_HTTP_PACKET_SIZE:(i + 1) * MAX_HTTP_PACKET_SIZE]))
 
     @unpack_cell(HTTPResponsePayload)
     def on_http_response(self, source_address, payload, circuit_id):

src/tribler/core/components/tunnel/tests/test_triblertunnel_community.py

@@ -2,8 +2,9 @@
 from asyncio import Future, TimeoutError as AsyncTimeoutError, sleep, wait_for
 from collections import defaultdict
 from random import random
-from unittest.mock import Mock
+from unittest.mock import MagicMock, Mock, patch
 
+import pytest
 from ipv8.messaging.anonymization.payload import EstablishIntroPayload
 from ipv8.messaging.anonymization.tunnel import (
     CIRCUIT_STATE_READY,
@@ -12,6 +13,7 @@
     PEER_FLAG_EXIT_BT,
 )
 from ipv8.peer import Peer
+from ipv8.peerdiscovery.network import Network
 from ipv8.test.base import TestBase
 from ipv8.test.messaging.anonymization import test_community
 from ipv8.test.messaging.anonymization.test_community import MockDHTProvider
@@ -34,6 +36,24 @@
 from tribler.core.utilities.utilities import MEMORY_DB
 
 
+# pylint: disable=redefined-outer-name
+
+@pytest.fixture()
+def tunnel_community():
+    community = TriblerTunnelCommunity(MagicMock(),
+                                       MagicMock(),
+                                       MagicMock(),
+                                       socks_servers=MagicMock(),
+                                       config=MagicMock(),
+                                       notifier=MagicMock(),
+                                       dlmgr=MagicMock(),
+                                       bandwidth_community=MagicMock(),
+                                       dht_provider=MagicMock(),
+                                       exitnode_cache=MagicMock(),
+                                       settings=MagicMock())
+    return community
+
+
 class TestTriblerTunnelCommunity(TestBase):  # pylint: disable=too-many-public-methods
 
     def setUp(self):
@@ -180,6 +200,7 @@ def test_monitor_downloads_recreate_ip(self):
 
         def mock_create_ip(*_, **__):
             mock_create_ip.called = True
+
         mock_create_ip.called = False
         self.nodes[0].overlay.create_introduction_point = mock_create_ip
 
@@ -200,8 +221,10 @@ def test_monitor_downloads_intro(self):
         """
         Test whether rendezvous points are removed when a download is stopped
         """
+
         def mocked_remove_circuit(circuit_id, *_, **__):
             mocked_remove_circuit.circuit_id = circuit_id
+
         mocked_remove_circuit.circuit_id = -1
 
         mock_circuit = MockObject()
@@ -224,8 +247,10 @@ def test_monitor_downloads_stop_all(self):
         """
         Test whether circuits are removed when all downloads are stopped
         """
+
         def mocked_remove_circuit(circuit_id, *_, **__):
             mocked_remove_circuit.circuit_id = circuit_id
+
         mocked_remove_circuit.circuit_id = -1
 
         mock_circuit = MockObject()
@@ -644,3 +669,21 @@ async def test_perform_http_request_failed(self):
             await wait_for(self.nodes[0].overlay.perform_http_request(('127.0.0.1', 1234),
                                                                       b'GET /scrape?info_hash=0 HTTP/1.1\r\n\r\n'),
                            timeout=.3)
+
+
+@patch.object(Network, 'snapshot', Mock(return_value=b'snapshot'))
+def test_cache_exitnodes_to_disk(tunnel_community: TriblerTunnelCommunity, tmp_path):
+    """ Test whether we can cache exit nodes to disk """
+    tunnel_community.exitnode_cache = tmp_path / 'exitnode_cache.dat'
+    tunnel_community.cache_exitnodes_to_disk()
+
+    assert tunnel_community.exitnode_cache.read_bytes() == b'snapshot'
+
+
+@patch.object(Network, 'snapshot', Mock(return_value=b'snapshot'))
+def test_cache_exitnodes_to_disk_os_error(tunnel_community: TriblerTunnelCommunity):
+    """ Test whether we can handle an OSError when caching exit nodes to disk and raise no errors """
+    tunnel_community.exitnode_cache = Mock(write_bytes=Mock(side_effect=FileNotFoundError))
+    tunnel_community.cache_exitnodes_to_disk()
+
+    assert tunnel_community.exitnode_cache.write_bytes.called