Fix #5975: Forget or redeem channels that are never funded.

- initiator: wait until double spent
 - non-initiator: wait until timeout

electrum/gui/qt/channels_list.py

@@ -120,10 +120,12 @@ class ChannelsList(MyTreeView):
                 menu.addAction(_("Close channel"), lambda: self.close_channel(channel_id))
             menu.addAction(_("Force-close channel"), lambda: self.force_close(channel_id))
         else:
-            txid, height, timestamp = chan.get_closing_height()
-            closing_tx = self.lnworker.lnwatcher.db.get_transaction(txid)
-            if closing_tx:
-                menu.addAction(_("View closing transaction"), lambda: self.parent.show_transaction(closing_tx))
+            item = chan.get_closing_height()
+            if item:
+                txid, height, timestamp = item
+                closing_tx = self.lnworker.lnwatcher.db.get_transaction(txid)
+                if closing_tx:
+                    menu.addAction(_("View closing transaction"), lambda: self.parent.show_transaction(closing_tx))
         if chan.is_redeemed():
             menu.addAction(_("Remove"), lambda: self.remove_channel(channel_id))
         menu.exec_(self.viewport().mapToGlobal(position))

electrum/lnchannel.py

@@ -97,6 +97,7 @@ state_transitions = [
     (cs.CLOSING, cs.CLOSED),
     (cs.FORCE_CLOSING, cs.CLOSED),
     (cs.CLOSED, cs.REDEEMED),
+    (cs.PREOPENING, cs.REDEEMED), # channel never funded
 ]
 del cs  # delete as name is ambiguous without context
 

electrum/lnpeer.py

@@ -590,6 +590,7 @@ class Peer(Logger):
                        sweep_address=self.lnworker.sweep_address,
                        lnworker=self.lnworker,
                        initial_feerate=feerate)
+        chan.storage['funding_inputs'] = [txin.prevout for txin in funding_tx.inputs()]
         sig_64, _ = chan.sign_next_commitment()
         self.temp_id_to_id[temp_channel_id] = channel_id
         self.send_message("funding_created",
@@ -684,6 +685,7 @@ class Peer(Logger):
                        sweep_address=self.lnworker.sweep_address,
                        lnworker=self.lnworker,
                        initial_feerate=feerate)
+        chan.storage['init_timestamp'] = int(time.time())
         remote_sig = funding_created['signature']
         chan.receive_new_commitment(remote_sig, [])
         sig_64, _ = chan.sign_next_commitment()

electrum/lnwatcher.py

@@ -322,6 +322,9 @@ class WatchTower(LNWatcher):
         pass
 
 
+
+CHANNEL_OPENING_TIMEOUT = 24*60*60
+
 class LNWalletWatcher(LNWatcher):
 
     def __init__(self, lnworker, network):
@@ -337,7 +340,7 @@ class LNWalletWatcher(LNWatcher):
             return
         if funding_height.height == TX_HEIGHT_LOCAL:
             chan.delete_funding_height()
-            return
+            await self.lnworker.update_unfunded_channel(chan, funding_txid)
         elif closing_height.height == TX_HEIGHT_LOCAL:
             chan.save_funding_height(funding_txid, funding_height.height, funding_height.timestamp)
             await self.lnworker.update_open_channel(chan, funding_txid, funding_height)

electrum/lnworker.py

@@ -654,6 +654,29 @@ class LNWallet(LNWorker):
             if chan.funding_outpoint.to_str() == txo:
                 return chan
 
+    async def update_unfunded_channel(self, chan, funding_txid):
+        if chan.get_state() in [channel_states.PREOPENING, channel_states.OPENING]:
+            if chan.constraints.is_initiator:
+                inputs = chan.storage.get('funding_inputs', [])
+                if not inputs:
+                    self.logger.info(f'channel funding inputs are not provided')
+                    chan.set_state(channel_states.REDEEMED)
+                for i in inputs:
+                    spender_txid = self.wallet.db.get_spent_outpoint(*i)
+                    if spender_txid is None:
+                        continue
+                    if spender_txid != funding_txid:
+                        tx_mined_height = self.wallet.get_tx_height(spender_txid)
+                        if tx_mined_height.conf > 6:
+                            self.logger.info(f'channel is double spent {inputs}, {ds}')
+                            # set to REDEEMED so that it can be removed manually
+                            chan.set_state(channel_states.REDEEMED)
+                            break
+            else:
+                now = int(time.time())
+                if now - chan.storage.get('init_timestamp', 0) > CHANNEL_INIT_TIMEOUT:
+                    self.remove_channel(chan.channel_id)
+
     async def update_open_channel(self, chan, funding_txid, funding_height):
 
         if chan.get_state() == channel_states.OPEN and self.should_channel_be_closed_due_to_expiring_htlcs(chan):