From b55f9e9e6a2a578c9bd642baeef108e998bb379e Mon Sep 17 00:00:00 2001
From: ThomasV <thomasv@electrum.org>
Date: Sat, 13 Jul 2019 08:46:17 +0200
Subject: [PATCH] Do not route through channels for which we did not receive
 both updates, because this often means one of the nodes is offline.

---
 electrum/channel_db.py | 10 ++++++++++
 electrum/lnpeer.py     |  3 +--
 electrum/lnrouter.py   | 10 +++++++++-
 3 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/electrum/channel_db.py b/electrum/channel_db.py
index fef988454..79aa9a159 100644
--- a/electrum/channel_db.py
+++ b/electrum/channel_db.py
@@ -527,6 +527,16 @@ class ChannelDB(SqlDB):
             self._channels_for_node[channel_info.node2_id].add(channel_info.short_channel_id)
         self.logger.info(f'load data {len(self._channels)} {len(self._policies)} {len(self._channels_for_node)}')
         self.update_counts()
+        self.count_incomplete_channels()
+
+    def count_incomplete_channels(self):
+        out = set()
+        for short_channel_id, ci in self._channels.items():
+            p1 = self.get_policy_for_node(short_channel_id, ci.node1_id)
+            p2 = self.get_policy_for_node(short_channel_id, ci.node2_id)
+            if p1 is None or p2 is not None:
+                out.add(short_channel_id)
+        self.logger.info(f'semi-orphaned: {len(out)}')
 
     def get_policy_for_node(self, short_channel_id: bytes, node_id: bytes) -> Optional['Policy']:
         return self._policies.get((node_id, short_channel_id))
diff --git a/electrum/lnpeer.py b/electrum/lnpeer.py
index 9ddbd9492..04b2c398a 100644
--- a/electrum/lnpeer.py
+++ b/electrum/lnpeer.py
@@ -1019,8 +1019,7 @@ class Peer(Logger):
             except IndexError:
                 self.logger.info("payment destination reported error")
             else:
-                self.logger.info(f'blacklisting channel {bh2u(short_chan_id)}')
-                self.network.path_finder.blacklist.add(short_chan_id)
+                self.network.path_finder.add_to_blacklist(short_chan_id)
 
     def maybe_send_commitment(self, chan: Channel):
         ctn_to_sign = chan.get_current_ctn(REMOTE) + 1
diff --git a/electrum/lnrouter.py b/electrum/lnrouter.py
index 4a8354746..7fe67e354 100644
--- a/electrum/lnrouter.py
+++ b/electrum/lnrouter.py
@@ -129,6 +129,10 @@ class LNPathFinder(Logger):
         self.channel_db = channel_db
         self.blacklist = set()
 
+    def add_to_blacklist(self, short_channel_id):
+        self.logger.info(f'blacklisting channel {bh2u(short_channel_id)}')
+        self.blacklist.add(short_channel_id)
+
     def _edge_cost(self, short_channel_id: bytes, start_node: bytes, end_node: bytes,
                    payment_amt_msat: int, ignore_costs=False) -> Tuple[float, int]:
         """Heuristic cost of going through a channel.
@@ -140,7 +144,11 @@ class LNPathFinder(Logger):
         channel_policy = self.channel_db.get_policy_for_node(short_channel_id, start_node)
         if channel_policy is None:
             return float('inf'), 0
-        if channel_policy.is_disabled(): return float('inf'), 0
+        # channels that did not publish both policies often return temporary channel failure
+        if self.channel_db.get_policy_for_node(short_channel_id, end_node) is None:
+            return float('inf'), 0
+        if channel_policy.is_disabled():
+            return float('inf'), 0
         route_edge = RouteEdge.from_channel_policy(channel_policy, short_channel_id, end_node)
         if payment_amt_msat < channel_policy.htlc_minimum_msat:
             return float('inf'), 0  # payment amount too little