pass blacklist to lnrouter.find_route, so that lnrouter is stateless (see #6778)

electrum/lnrouter.py

@@ -135,24 +135,12 @@ def is_fee_sane(fee_msat: int, *, payment_amount_msat: int) -> bool:
     return False
 
 
-BLACKLIST_DURATION = 3600
 
 class LNPathFinder(Logger):
 
     def __init__(self, channel_db: ChannelDB):
         Logger.__init__(self)
         self.channel_db = channel_db
-        self.blacklist = dict() # short_chan_id -> timestamp
-
-    def add_to_blacklist(self, short_channel_id: ShortChannelID):
-        self.logger.info(f'blacklisting channel {short_channel_id}')
-        now = int(time.time())
-        self.blacklist[short_channel_id] = now
-
-    def is_blacklisted(self, short_channel_id: ShortChannelID) -> bool:
-        now = int(time.time())
-        t = self.blacklist.get(short_channel_id, 0)
-        return now - t < BLACKLIST_DURATION
 
     def _edge_cost(self, short_channel_id: bytes, start_node: bytes, end_node: bytes,
                    payment_amt_msat: int, ignore_costs=False, is_mine=False, *,
@@ -200,10 +188,9 @@ class LNPathFinder(Logger):
         overall_cost = base_cost + fee_msat + cltv_cost
         return overall_cost, fee_msat
 
-    def get_distances(self, nodeA: bytes, nodeB: bytes,
+    def get_distances(self, nodeA: bytes, nodeB: bytes, invoice_amount_msat: int, *,
-                      invoice_amount_msat: int, *,
+                      my_channels: Dict[ShortChannelID, 'Channel'] = None,
-                      my_channels: Dict[ShortChannelID, 'Channel'] = None
+                      blacklist: Set[ShortChannelID] = None) -> Dict[bytes, PathEdge]:
-                      ) -> Dict[bytes, PathEdge]:
         # note: we don't lock self.channel_db, so while the path finding runs,
         #       the underlying graph could potentially change... (not good but maybe ~OK?)
 
@@ -216,7 +203,6 @@ class LNPathFinder(Logger):
         nodes_to_explore = queue.PriorityQueue()
         nodes_to_explore.put((0, invoice_amount_msat, nodeB))  # order of fields (in tuple) matters!
 
-
         # main loop of search
         while nodes_to_explore.qsize() > 0:
             dist_to_edge_endnode, amount_msat, edge_endnode = nodes_to_explore.get()
@@ -229,7 +215,7 @@ class LNPathFinder(Logger):
                 continue
             for edge_channel_id in self.channel_db.get_channels_for_node(edge_endnode, my_channels=my_channels):
                 assert isinstance(edge_channel_id, bytes)
-                if self.is_blacklisted(edge_channel_id):
+                if blacklist and edge_channel_id in blacklist:
                     continue
                 channel_info = self.channel_db.get_channel_info(edge_channel_id, my_channels=my_channels)
                 edge_startnode = channel_info.node2_id if channel_info.node1_id == edge_endnode else channel_info.node1_id
@@ -263,7 +249,8 @@ class LNPathFinder(Logger):
     @profiler
     def find_path_for_payment(self, nodeA: bytes, nodeB: bytes,
                               invoice_amount_msat: int, *,
-                              my_channels: Dict[ShortChannelID, 'Channel'] = None) \
+                              my_channels: Dict[ShortChannelID, 'Channel'] = None,
+                              blacklist: Set[ShortChannelID] = None) \
             -> Optional[LNPaymentPath]:
         """Return a path from nodeA to nodeB."""
         assert type(nodeA) is bytes
@@ -272,7 +259,7 @@ class LNPathFinder(Logger):
         if my_channels is None:
             my_channels = {}
 
-        prev_node = self.get_distances(nodeA, nodeB, invoice_amount_msat, my_channels=my_channels)
+        prev_node = self.get_distances(nodeA, nodeB, invoice_amount_msat, my_channels=my_channels, blacklist=blacklist)
 
         if nodeA not in prev_node:
             return None  # no path found
@@ -312,8 +299,9 @@ class LNPathFinder(Logger):
         return route
 
     def find_route(self, nodeA: bytes, nodeB: bytes, invoice_amount_msat: int, *,
-                   path = None, my_channels: Dict[ShortChannelID, 'Channel'] = None) -> Optional[LNPaymentRoute]:
+                   path = None, my_channels: Dict[ShortChannelID, 'Channel'] = None,
+                   blacklist: Set[ShortChannelID] = None) -> Optional[LNPaymentRoute]:
         if not path:
-            path = self.find_path_for_payment(nodeA, nodeB, invoice_amount_msat, my_channels=my_channels)
+            path = self.find_path_for_payment(nodeA, nodeB, invoice_amount_msat, my_channels=my_channels, blacklist=blacklist)
         if path:
             return self.create_route_from_path(path, nodeA, my_channels=my_channels)

electrum/lnutil.py

@@ -8,7 +8,7 @@ import json
 from collections import namedtuple, defaultdict
 from typing import NamedTuple, List, Tuple, Mapping, Optional, TYPE_CHECKING, Union, Dict, Set, Sequence
 import re
-
+import time
 import attr
 from aiorpcx import NetAddress
 
@@ -1313,3 +1313,17 @@ class OnionFailureCodeMetaFlag(IntFlag):
     NODE     = 0x2000
     UPDATE   = 0x1000
 
+
+class ChannelBlackList:
+
+    def __init__(self):
+        self.blacklist = dict() # short_chan_id -> timestamp
+
+    def add(self, short_channel_id: ShortChannelID):
+        now = int(time.time())
+        self.blacklist[short_channel_id] = now
+
+    def get_current_list(self) -> Set[ShortChannelID]:
+        BLACKLIST_DURATION = 3600
+        now = int(time.time())
+        return set(k for k, t in self.blacklist.items() if now - t < BLACKLIST_DURATION)

electrum/lnworker.py

@@ -7,7 +7,7 @@ import os
 from decimal import Decimal
 import random
 import time
-from typing import Optional, Sequence, Tuple, List, Dict, TYPE_CHECKING, NamedTuple, Union, Mapping, Any
+from typing import Optional, Sequence, Tuple, List, Set, Dict, TYPE_CHECKING, NamedTuple, Union, Mapping, Any
 import threading
 import socket
 import aiohttp
@@ -540,6 +540,7 @@ class LNGossip(LNWorker):
             if categorized_chan_upds.good:
                 self.logger.debug(f'on_channel_update: {len(categorized_chan_upds.good)}/{len(chan_upds_chunk)}')
 
+
 class LNWallet(LNWorker):
 
     lnwatcher: Optional['LNWalletWatcher']
@@ -1014,7 +1015,8 @@ class LNWallet(LNWorker):
                     except IndexError:
                         self.logger.info("payment destination reported error")
                     else:
-                        self.network.path_finder.add_to_blacklist(short_chan_id)
+                        self.logger.info(f'blacklisting channel {short_channel_id}')
+                        self.network.channel_blacklist.add(short_chan_id)
             else:
                 # probably got "update_fail_malformed_htlc". well... who to penalise now?
                 assert payment_attempt.failure_message is not None
@@ -1127,6 +1129,7 @@ class LNWallet(LNWorker):
         channels = list(self.channels.values())
         scid_to_my_channels = {chan.short_channel_id: chan for chan in channels
                                if chan.short_channel_id is not None}
+        blacklist = self.network.channel_blacklist.get_current_list()
         for private_route in r_tags:
             if len(private_route) == 0:
                 continue
@@ -1144,7 +1147,7 @@ class LNWallet(LNWorker):
             try:
                 route = self.network.path_finder.find_route(
                     self.node_keypair.pubkey, border_node_pubkey, amount_msat,
-                    path=path, my_channels=scid_to_my_channels)
+                    path=path, my_channels=scid_to_my_channels, blacklist=blacklist)
             except NoChannelPolicy:
                 continue
             if not route:
@@ -1186,7 +1189,7 @@ class LNWallet(LNWorker):
         if route is None:
             route = self.network.path_finder.find_route(
                 self.node_keypair.pubkey, invoice_pubkey, amount_msat,
-                path=full_path, my_channels=scid_to_my_channels)
+                path=full_path, my_channels=scid_to_my_channels, blacklist=blacklist)
             if not route:
                 raise NoPathFound()
             if not is_route_sane_to_use(route, amount_msat, decoded_invoice.get_min_final_cltv_expiry()):

electrum/network.py

@@ -45,7 +45,6 @@ from . import util
 from .util import (log_exceptions, ignore_exceptions,
                    bfh, SilentTaskGroup, make_aiohttp_session, send_exception_to_crash_reporter,
                    is_hash256_str, is_non_negative_integer, MyEncoder, NetworkRetryManager)
-
 from .bitcoin import COIN
 from . import constants
 from . import blockchain
@@ -60,6 +59,7 @@ from .version import PROTOCOL_VERSION
 from .simple_config import SimpleConfig
 from .i18n import _
 from .logging import get_logger, Logger
+from .lnutil import ChannelBlackList
 
 if TYPE_CHECKING:
     from .channel_db import ChannelDB
@@ -335,6 +335,7 @@ class Network(Logger, NetworkRetryManager[ServerAddr]):
         self._has_ever_managed_to_connect_to_server = False
 
         # lightning network
+        self.channel_blacklist = ChannelBlackList()
         self.channel_db = None  # type: Optional[ChannelDB]
         self.lngossip = None  # type: Optional[LNGossip]
         self.local_watchtower = None  # type: Optional[WatchTower]

electrum/tests/test_lnpeer.py

@@ -32,6 +32,7 @@ from electrum.lnmsg import encode_msg, decode_msg
 from electrum.logging import console_stderr_handler, Logger
 from electrum.lnworker import PaymentInfo, RECEIVED, PR_UNPAID
 from electrum.lnonion import OnionFailureCode
+from electrum.lnutil import ChannelBlackList
 
 from .test_lnchannel import create_test_channels
 from .test_bitcoin import needs_test_with_all_chacha20_implementations
@@ -62,6 +63,7 @@ class MockNetwork:
         self.path_finder = LNPathFinder(self.channel_db)
         self.tx_queue = tx_queue
         self._blockchain = MockBlockchain()
+        self.channel_blacklist = ChannelBlackList()
 
     @property
     def callback_lock(self):