Open lightning channels with partially signed tx.

Fixes #5379.

electrum/commands.py

@@ -929,7 +929,7 @@ class Commands:
         push_sat = satoshis(push_amount)
         dummy_output = PartialTxOutput.from_address_and_value(ln_dummy_address(), funding_sat)
         funding_tx = wallet.mktx(outputs = [dummy_output], rbf=False, sign=False, nonlocal_only=True)
-        chan = await wallet.lnworker._open_channel_coroutine(connection_string, funding_tx, funding_sat, push_sat, password)
+        chan, funding_tx = await wallet.lnworker._open_channel_coroutine(connection_string, funding_tx, funding_sat, push_sat, password)
         return chan.funding_outpoint.to_str()
 
     @command('wn')

electrum/gui/kivy/uix/dialogs/lightning_open_channel.py

@@ -138,7 +138,7 @@ class LightningOpenChannelDialog(Factory.Popup):
 
     def do_open_channel(self, conn_str, amount, password):
         try:
-            chan = self.app.wallet.lnworker.open_channel(conn_str, amount, 0, password=password)
+            chan, funding_tx = self.app.wallet.lnworker.open_channel(conn_str, amount, 0, password=password)
         except Exception as e:
             self.app.show_error(_('Problem opening channel: ') + '\n' + repr(e))
             return
@@ -148,4 +148,8 @@ class LightningOpenChannelDialog(Factory.Popup):
             _('Remote peer ID') + ':' + chan.node_id.hex(),
             _('This channel will be usable after {} confirmations').format(n)
         ])
+        if not funding_tx.is_complete():
+            message += '\n\n' + _('Please sign and broadcast the funding transaction')
         self.app.show_info(message)
+        if not funding_tx.is_complete():
+            self.app.tx_dialog(funding_tx)

electrum/gui/qt/main_window.py

@@ -1636,14 +1636,20 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger):
         funding_sat = funding_tx.output_value_for_address(ln_dummy_address())
         def task():
             return self.wallet.lnworker.open_channel(connect_str, funding_tx, funding_sat, push_amt, password)
-        def on_success(chan):
+        def on_success(args):
+            chan, funding_tx = args
             n = chan.constraints.funding_txn_minimum_depth
             message = '\n'.join([
                 _('Channel established.'),
                 _('Remote peer ID') + ':' + chan.node_id.hex(),
                 _('This channel will be usable after {} confirmations').format(n)
             ])
+            if not funding_tx.is_complete():
+                message += '\n\n' + _('Please sign and broadcast the funding transaction')
             self.show_message(message)
+            if not funding_tx.is_complete():
+                self.show_transaction(funding_tx)
+
         def on_failure(exc_info):
             type_, e, traceback = exc_info
             self.show_error(_('Could not open channel: {}').format(e))

electrum/lnpeer.py

@@ -575,6 +575,8 @@ class Peer(Logger):
         funding_tx.add_outputs([funding_output])
         funding_tx.set_rbf(False)
         self.lnworker.wallet.sign_transaction(funding_tx, password)
+        if not funding_tx.is_complete() and not funding_tx.is_segwit():
+            raise Exception(_('Funding transaction is not complete'))
         funding_txid = funding_tx.txid()
         funding_index = funding_tx.outputs().index(funding_output)
         # remote commitment transaction
@@ -605,10 +607,7 @@ class Peer(Logger):
         remote_sig = payload['signature']
         chan.receive_new_commitment(remote_sig, [])
         chan.open_with_first_pcp(remote_per_commitment_point, remote_sig)
-        # broadcast funding tx
-        # TODO make more robust (timeout low? server returns error?)
-        await asyncio.wait_for(self.network.broadcast_transaction(funding_tx), LN_P2P_NETWORK_TIMEOUT)
-        return chan
+        return chan, funding_tx
 
     async def on_open_channel(self, payload):
         # payload['channel_flags']

electrum/lnworker.py

@@ -812,7 +812,7 @@ class LNWallet(LNWorker):
         peer = await self.add_peer(connect_str)
         # peer might just have been connected to
         await asyncio.wait_for(peer.initialized.wait(), LN_P2P_NETWORK_TIMEOUT)
-        chan = await peer.channel_establishment_flow(
+        chan, funding_tx = await peer.channel_establishment_flow(
             password,
             funding_tx=funding_tx,
             funding_sat=funding_sat,
@@ -821,7 +821,10 @@ class LNWallet(LNWorker):
         self.save_channel(chan)
         self.lnwatcher.add_channel(chan.funding_outpoint.to_str(), chan.get_funding_address())
         self.network.trigger_callback('channels_updated', self.wallet)
-        return chan
+        if funding_tx.is_complete():
+            # TODO make more robust (timeout low? server returns error?)
+            await asyncio.wait_for(self.network.broadcast_transaction(funding_tx), LN_P2P_NETWORK_TIMEOUT)
+        return chan, funding_tx
 
     @log_exceptions
     async def add_peer(self, connect_str: str) -> Peer:
@@ -858,10 +861,10 @@ class LNWallet(LNWorker):
         coro = self._open_channel_coroutine(connect_str, funding_tx, funding_sat, push_amt_sat, password)
         fut = asyncio.run_coroutine_threadsafe(coro, self.network.asyncio_loop)
         try:
-            chan = fut.result(timeout=timeout)
+            chan, funding_tx = fut.result(timeout=timeout)
         except concurrent.futures.TimeoutError:
             raise Exception(_("open_channel timed out"))
-        return chan
+        return chan, funding_tx
 
     def pay(self, invoice, amount_sat=None, attempts=1):
         """