swaps: make the zeroconf option non-persisted

Since we allow swaps with random servers, we should not persist that setting.

electrum/gui/qt/swap_dialog.py

@@ -44,8 +44,8 @@ class SwapDialog(WindowModalDialog, QtEventListener):
         self.is_reverse = is_reverse if is_reverse is not None else True
         vbox = QVBoxLayout(self)
         toolbar, menu = create_toolbar_with_menu(self.config, '')
-        menu.addConfig(
-            self.config.cv.LIGHTNING_ALLOW_INSTANT_SWAPS,
+        menu.addToggle(
+            _('Zeroconf swap'), self.toggle_zeroconf
         ).setEnabled(self.lnworker.can_have_recoverable_channels())
         if not self.config.SWAPSERVER_URL:
             menu.addAction(_('Choose swap server'), lambda: self.window.choose_swapserver_dialog(transport))
@@ -62,6 +62,7 @@ class SwapDialog(WindowModalDialog, QtEventListener):
         # send_follows is used to know whether the send amount field / receive
         # amount field should be adjusted after the fee slider was moved
         self.send_follows = False
+        self.zeroconf = False
         self.send_amount_e.follows = False
         self.recv_amount_e.follows = False
         self.toggle_button.clicked.connect(self.toggle_direction)
@@ -108,6 +109,15 @@ class SwapDialog(WindowModalDialog, QtEventListener):
         self.window.gui_object.timer.timeout.connect(self.timer_actions)
         self.register_callbacks()
 
+    def toggle_zeroconf(self):
+        self.zeroconf = not self.zeroconf
+        if self.zeroconf:
+            msg = "\n\n".join([
+                "Zero-confirmation swap: Your wallet will not wait until the funding transaction is confirmed.",
+                "Note that this option is risky: the server can steal your funds if they double-spend the funding transaction."
+            ])
+            self.window.show_warning(msg)
+
     def closeEvent(self, event):
         self.unregister_callbacks()
         event.accept()
@@ -255,10 +265,11 @@ class SwapDialog(WindowModalDialog, QtEventListener):
                 return
             sm = self.swap_manager
             coro = sm.reverse_swap(
-                    transport,
-                    lightning_amount_sat=lightning_amount,
-                    expected_onchain_amount_sat=onchain_amount + self.swap_manager.get_claim_fee(),
-                )
+                transport,
+                lightning_amount_sat=lightning_amount,
+                expected_onchain_amount_sat=onchain_amount + self.swap_manager.get_claim_fee(),
+                zeroconf=self.zeroconf,
+            )
             # we must not leave the context, so we use run_couroutine_dialog
             funding_txid = self.window.run_coroutine_dialog(coro, _('Initiating swap...'))
             self.window.on_swap_result(funding_txid, is_reverse=True)

electrum/simple_config.py

@@ -1016,13 +1016,6 @@ Downloading the network gossip uses quite some bandwidth and storage, and is not
 Note that static backups only allow you to request a force-close with the remote node. This assumes that the remote node is still online, did not lose its data, and accepts to force close the channel.
 
 If this is enabled, other nodes cannot open a channel to you. Channel recovery data is encrypted, so that only your wallet can decrypt it. However, blockchain analysis will be able to tell that the transaction was probably created by Electrum."""),
-    )
-    LIGHTNING_ALLOW_INSTANT_SWAPS = ConfigVar(
-        'allow_instant_swaps', default=False, type_=bool,
-        short_desc=lambda: _("Allow instant swaps"),
-        long_desc=lambda: _("""If this option is checked, your client will complete reverse swaps before the funding transaction is confirmed.
-
-Note you are at risk of losing the funds in the swap, if the funding transaction never confirms."""),
     )
     LIGHTNING_TO_SELF_DELAY_CSV = ConfigVar('lightning_to_self_delay', default=7 * 144, type_=int)
     LIGHTNING_MAX_FUNDING_SAT = ConfigVar('lightning_max_funding_sat', default=LN_MAX_FUNDING_SAT_LEGACY, type_=int)

electrum/submarine_swaps.py

@@ -152,6 +152,7 @@ class SwapData(StoredObject):
 
     _funding_prevout = None  # type: Optional[TxOutpoint]  # for RBF
     _payment_hash = None
+    _zeroconf = False
 
     @property
     def payment_hash(self) -> bytes:
@@ -351,7 +352,7 @@ class SwapManager(Logger):
                         self.lnwatcher.remove_callback(swap.lockup_address)
                         swap.is_redeemed = True
                 elif spent_height == TX_HEIGHT_LOCAL:
-                    if funding_height.conf > 0 or (swap.is_reverse and self.wallet.config.LIGHTNING_ALLOW_INSTANT_SWAPS):
+                    if funding_height.conf > 0 or (swap.is_reverse and swap._zeroconf):
                         tx = self.lnwatcher.adb.get_transaction(txin.spent_txid)
                         try:
                             await self.network.broadcast_transaction(tx)
@@ -428,7 +429,7 @@ class SwapManager(Logger):
             self.logger.info(f'adding claim tx {tx.txid()}')
             self.wallet.adb.add_transaction(tx)
             swap.spending_txid = tx.txid()
-            if funding_height.conf > 0 or (swap.is_reverse and self.wallet.config.LIGHTNING_ALLOW_INSTANT_SWAPS):
+            if funding_height.conf > 0 or (swap.is_reverse and swap._zeroconf):
                 try:
                     await self.network.broadcast_transaction(tx)
                 except TxBroadcastError:
@@ -823,6 +824,7 @@ class SwapManager(Logger):
             *,
             lightning_amount_sat: int,
             expected_onchain_amount_sat: int,
+            zeroconf: bool=False,
             channels: Optional[Sequence['Channel']] = None,
     ) -> Optional[str]:
         """send on Lightning, receive on-chain
@@ -903,6 +905,7 @@ class SwapManager(Logger):
             prepay_hash=prepay_hash,
             onchain_amount_sat=onchain_amount,
             lightning_amount_sat=lightning_amount_sat)
+        swap._zeroconf = zeroconf
         # initiate fee payment.
         if fee_invoice:
             asyncio.ensure_future(self.lnworker.pay_invoice(fee_invoice))