create_trampoline_route: check that we can pay the amount and the fees, and that the route is sane

electrum/lnworker.py

@@ -1281,6 +1281,7 @@ class LNWallet(LNWorker):
 
     def create_trampoline_route(
             self, amount_msat:int,
+            min_cltv_expiry:int,
             invoice_pubkey:bytes,
             invoice_features:int,
             channels: List[Channel],
@@ -1304,16 +1305,17 @@ class LNWallet(LNWorker):
         else:
             is_legacy = True
 
+        # fee level. the same fee is used for all trampolines
+        if self.trampoline_fee_level < len(TRAMPOLINE_FEES):
+            params = TRAMPOLINE_FEES[self.trampoline_fee_level]
+        else:
+            raise NoPathFound()
         # Find a trampoline. We assume we have a direct channel to trampoline
         for chan in channels:
             if not self.is_trampoline_peer(chan.node_id):
                 continue
-            if chan.is_active() and chan.can_pay(amount_msat, check_frozen=True):
             trampoline_short_channel_id = chan.short_channel_id
             trampoline_node_id = chan.node_id
-                break
-        else:
-            raise NoPathFound()
             # use attempt number to decide fee and second trampoline
             # we need a state with the list of nodes we have not tried
             # add optional second trampoline
@@ -1323,15 +1325,6 @@ class LNWallet(LNWorker):
                     if node_id != trampoline_node_id:
                         trampoline2 = node_id
                         break
-        # fee level. the same fee is used for all trampolines
-        if self.trampoline_fee_level < len(TRAMPOLINE_FEES):
-            params = TRAMPOLINE_FEES[self.trampoline_fee_level]
-        else:
-            raise NoPathFound()
-        self.logger.info(f'create route with trampoline: fee_level={self.trampoline_fee_level}, is legacy: {is_legacy}')
-        self.logger.info(f'first trampoline: {trampoline_node_id.hex()}')
-        self.logger.info(f'second trampoline: {trampoline2.hex() if trampoline2 else None}')
-        self.logger.info(f'params: {params}')
             # node_features is only used to determine is_tlv
             trampoline_features = LnFeatures.VAR_ONION_OPT
             # hop to trampoline
@@ -1384,6 +1377,20 @@ class LNWallet(LNWorker):
                     fee_proportional_millionths=0,
                     cltv_expiry_delta=0,
                     node_features=trampoline_features))
+            # check that we can pay amount and fees
+            for edge in route[::-1]:
+                amount_msat += edge.fee_for_edge(amount_msat)
+            if not chan.can_pay(amount_msat, check_frozen=True):
+                continue
+            if not is_route_sane_to_use(route, amount_msat, min_cltv_expiry):
+                continue
+            break
+        else:
+            raise NoPathFound()
+        self.logger.info(f'created route with trampoline: fee_level={self.trampoline_fee_level}, is legacy: {is_legacy}')
+        self.logger.info(f'first trampoline: {trampoline_node_id.hex()}')
+        self.logger.info(f'second trampoline: {trampoline2.hex() if trampoline2 else None}')
+        self.logger.info(f'params: {params}')
         return route
 
     @profiler
@@ -1422,7 +1429,6 @@ class LNWallet(LNWorker):
             # preference -funds = (low rating=high preference).
             split_configurations = suggest_splits(amount_msat, channels_with_funds)
             for s in split_configurations:
-                self.logger.info(f"trying split configuration: {s[0]} rating: {s[1]}")
                 routes = []
                 try:
                     for chanid, part_amount_msat in s[0].items():
@@ -1441,11 +1447,12 @@ class LNWallet(LNWorker):
                                 channel,
                                 full_path=None)
                             routes.append((route, amt))
+                    self.logger.info(f"found acceptable split configuration: {list(s[0].values())} rating: {s[1]}")
                     break
                 except NoPathFound:
                     continue
             else:
-                raise NoPathFound
+                raise NoPathFound()
         return routes
 
     def create_route_for_payment(
@@ -1461,7 +1468,7 @@ class LNWallet(LNWorker):
         channels = [outgoing_channel] if outgoing_channel else list(self.channels.values())
         if not self.channel_db:
             route = self.create_trampoline_route(
-                amount_msat, invoice_pubkey, invoice_features, channels, r_tags, t_tags)
+                amount_msat, min_cltv_expiry, invoice_pubkey, invoice_features, channels, r_tags, t_tags)
             return route, amount_msat
 
         route = None