lnworker._pay: allow specifying path as argument

not exposed to CLI/etc yet but will be used in tests soon

electrum/channel_db.py

@@ -119,7 +119,7 @@ class Policy(NamedTuple):
         return ShortChannelID.normalize(self.key[0:8])
 
     @property
-    def start_node(self):
+    def start_node(self) -> bytes:
         return self.key[8:]
 
 
@@ -732,5 +732,18 @@ class ChannelDB(SqlDB):
                 relevant_channels.add(chan.short_channel_id)
         return relevant_channels
 
+    def get_endnodes_for_chan(self, short_channel_id: ShortChannelID, *,
+                              my_channels: Dict[ShortChannelID, 'Channel'] = None) -> Optional[Tuple[bytes, bytes]]:
+        channel_info = self.get_channel_info(short_channel_id)
+        if channel_info is not None:  # publicly announced channel
+            return channel_info.node1_id, channel_info.node2_id
+        # check if it's one of our own channels
+        if not my_channels:
+            return
+        chan = my_channels.get(short_channel_id)  # type: Optional[Channel]
+        if not chan:
+            return
+        return chan.get_local_pubkey(), chan.node_id
+
     def get_node_info_for_node_id(self, node_id: bytes) -> Optional['NodeInfo']:
         return self._nodes.get(node_id)