allow transition from FORCE_CLOSING to REDEEMED. define REDEEM_AFTER_DOUBLE_SPENT_DELAY

electrum/lnchannel.py

@@ -99,6 +99,7 @@ state_transitions = [
     (cs.CLOSING, cs.CLOSING), # if we reestablish
     (cs.CLOSING, cs.CLOSED),
     (cs.FORCE_CLOSING, cs.CLOSED),
+    (cs.FORCE_CLOSING, cs.REDEEMED),
     (cs.CLOSED, cs.REDEEMED),
     (cs.OPENING, cs.REDEEMED), # channel never funded (dropped from mempool)
     (cs.PREOPENING, cs.REDEEMED), # channel never funded

electrum/lnutil.py

@@ -135,6 +135,7 @@ class PaymentFailure(UserFacingException): pass
 # TODO make some of these values configurable?
 DEFAULT_TO_SELF_DELAY = 144
 
+REDEEM_AFTER_DOUBLE_SPENT_DELAY = 30
 
 ##### CLTV-expiry-delta-related values
 # see https://github.com/lightningnetwork/lightning-rfc/blob/master/02-peer-protocol.md#cltv_expiry_delta-selection

electrum/lnworker.py

@@ -704,8 +704,11 @@ class LNWallet(LNWorker):
                 return chan
 
     async def update_unfunded_channel(self, chan, funding_txid):
-        if chan.get_state() in [channel_states.PREOPENING, channel_states.OPENING]:
+        if chan.get_state() in [channel_states.PREOPENING, channel_states.OPENING, channel_states.FORCE_CLOSING]:
             if chan.constraints.is_initiator:
+                # set channel state to REDEEMED so that it can be removed manually
+                # to protect ourselves against a server lying by omission,
+                # we check that funding_inputs have been double spent and deeply mined
                 inputs = chan.storage.get('funding_inputs', [])
                 if not inputs:
                     self.logger.info(f'channel funding inputs are not provided')
@@ -716,9 +719,8 @@ class LNWallet(LNWorker):
                         continue
                     if spender_txid != funding_txid:
                         tx_mined_height = self.wallet.get_tx_height(spender_txid)
-                        if tx_mined_height.conf > 6:
+                        if tx_mined_height.conf > lnutil.REDEEM_AFTER_DOUBLE_SPENT_DELAY:
                             self.logger.info(f'channel is double spent {inputs}')
-                            # set to REDEEMED so that it can be removed manually
                             chan.set_state(channel_states.REDEEMED)
                             break
             else: