lnpeer: forbid creating Peer with ourselves (self-connect)

related: #6583

electrum/lnpeer.py

@@ -82,6 +82,7 @@ class Peer(Logger):
         self.features = self.lnworker.features
         self.their_features = 0
         self.node_ids = [self.pubkey, privkey_to_pubkey(self.privkey)]
+        assert self.node_ids[0] != self.node_ids[1]
         self.network = lnworker.network
         self.channel_db = lnworker.network.channel_db
         self.ping_time = 0

electrum/lnworker.py

@@ -144,6 +144,9 @@ class NoPathFound(PaymentFailure):
         return _('No path found')
 
 
+class ErrorAddingPeer(Exception): pass
+
+
 class LNWorker(Logger, NetworkRetryManager[LNPeerAddr]):
 
     def __init__(self, xprv):
@@ -226,17 +229,22 @@ class LNWorker(Logger, NetworkRetryManager[LNPeerAddr]):
             peers = await self._get_next_peers_to_try()
             for peer in peers:
                 if self._can_retry_addr(peer, now=now):
-                    await self._add_peer(peer.host, peer.port, peer.pubkey)
+                    try:
+                        await self._add_peer(peer.host, peer.port, peer.pubkey)
+                    except ErrorAddingPeer as e:
+                        self.logger.info(f"failed to add peer: {peer}. exc: {e!r}")
 
     async def _add_peer(self, host: str, port: int, node_id: bytes) -> Peer:
         if node_id in self._peers:
             return self._peers[node_id]
         port = int(port)
         peer_addr = LNPeerAddr(host, port, node_id)
-        transport = LNTransport(self.node_keypair.privkey, peer_addr,
-                                proxy=self.network.proxy)
         self._trying_addr_now(peer_addr)
         self.logger.info(f"adding peer {peer_addr}")
+        if node_id == self.node_keypair.pubkey:
+            raise ErrorAddingPeer("cannot connect to self")
+        transport = LNTransport(self.node_keypair.privkey, peer_addr,
+                                proxy=self.network.proxy)
         peer = Peer(self, node_id, transport)
         await self.taskgroup.spawn(peer.main_loop())
         with self.lock: