Qt: add bolt11_fallback and bip21_lightning options to preferences

electrum/gui/qt/main_window.py

@@ -1268,11 +1268,11 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger):
 
     def show_receive_request(self, req):
         addr = req.get_address() or ''
-        URI = req.get_bip21_URI() if addr else ''
-        lnaddr = req.lightning_invoice or ''
         can_receive_lightning = self.wallet.lnworker and req.get_amount_sat() <= self.wallet.lnworker.num_sats_can_receive()
-        if not can_receive_lightning:
+        lnaddr = req.lightning_invoice if can_receive_lightning else None
-            lnaddr = ''
+        bip21_lightning = lnaddr if self.config.get('bip21_lightning', False) else None
+        URI = req.get_bip21_URI(lightning=bip21_lightning)
+        lnaddr = lnaddr or ''
         icon_name = "lightning.png" if can_receive_lightning else "lightning_disconnected.png"
         self.receive_tabs.setTabIcon(2, read_QIcon(icon_name))
         # encode lightning invoices as uppercase so QR encoding can use
@@ -1673,7 +1673,7 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger):
             choices = {}
             if can_pay_onchain:
                 msg = ''.join([
-                    _('Pay this invoice onchain'), '\n',
+                    _('Pay onchain'), '\n',
                     _('Funds will be sent to the invoice fallback address.')
                 ])
                 choices[0] = msg
@@ -1694,7 +1694,6 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger):
             msg = _('You cannot pay that invoice using Lightning.')
             if self.wallet.lnworker.channels:
                 msg += '\n' + _('Your channels can send {}.').format(self.format_amount(num_sats_can_send) + self.base_unit())
-
             r = self.query_choice(msg, choices)
             if r is not None:
                 self.save_pending_invoice()
@@ -2162,6 +2161,10 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger):
         amount = out.get('amount')
         label = out.get('label')
         message = out.get('message')
+        lightning = out.get('lightning')
+        if lightning:
+            self.set_ln_invoice(lightning)
+            return
         # use label as description (not BIP21 compliant)
         if label and not message:
             message = label

electrum/gui/qt/settings_dialog.py

@@ -97,6 +97,21 @@ class SettingsDialog(WindowModalDialog):
                 self.window.refresh_tabs()
         nz.valueChanged.connect(on_nz)
 
+        # invoices
+        bolt11_fallback_cb = QCheckBox(_('Add on-chain fallback to lightning invoices'))
+        bolt11_fallback_cb.setChecked(bool(self.config.get('bolt11_fallback', True)))
+        bolt11_fallback_cb.setToolTip(_('Add fallback addresses to BOLT11 lightning invoices.'))
+        def on_bolt11_fallback(x):
+            self.config.set_key('bolt11_fallback', bool(x))
+        bolt11_fallback_cb.stateChanged.connect(on_bolt11_fallback)
+
+        bip21_lightning_cb = QCheckBox(_('Add lightning invoice to bitcoin URIs'))
+        bip21_lightning_cb.setChecked(bool(self.config.get('bip21_lightning', False)))
+        bip21_lightning_cb.setToolTip(_('This may create larger qr codes.'))
+        def on_bip21_lightning(x):
+            self.config.set_key('bip21_lightning', bool(x))
+        bip21_lightning_cb.stateChanged.connect(on_bip21_lightning)
+
         use_rbf = bool(self.config.get('use_rbf', True))
         use_rbf_cb = QCheckBox(_('Use Replace-By-Fee'))
         use_rbf_cb.setChecked(use_rbf)
@@ -483,6 +498,9 @@ class SettingsDialog(WindowModalDialog):
         gui_widgets.append((nz_label, nz))
         gui_widgets.append((msat_cb, None))
         gui_widgets.append((thousandsep_cb, None))
+        invoices_widgets = []
+        invoices_widgets.append((bolt11_fallback_cb, None))
+        invoices_widgets.append((bip21_lightning_cb, None))
         tx_widgets = []
         tx_widgets.append((usechange_cb, None))
         tx_widgets.append((use_rbf_cb, None))
@@ -513,6 +531,7 @@ class SettingsDialog(WindowModalDialog):
 
         tabs_info = [
             (gui_widgets, _('Appearance')),
+            (invoices_widgets, _('Invoices')),
             (tx_widgets, _('Transactions')),
             (lightning_widgets, _('Lightning')),
             (fiat_widgets, _('Fiat')),

electrum/invoices.py

@@ -157,12 +157,21 @@ class Invoice(StoredObject):
             return None
         return int(amount_msat / 1000)
 
-    def get_bip21_URI(self):
+    def get_bip21_URI(self, lightning=None):
         from electrum.util import create_bip21_uri
         addr = self.get_address()
         amount = int(self.get_amount_sat())
         message = self.message
-        uri = create_bip21_uri(addr, amount, message)
+        extra = {}
+        if self.time and self.exp:
+            extra['time'] = str(self.time)
+            extra['exp'] = str(self.exp)
+        # only if we can receive
+        if lightning:
+            extra['lightning'] = lightning
+        if not addr and lightning:
+            return "bitcoin:?lightning="+lightning
+        uri = create_bip21_uri(addr, amount, message, extra_query_params=extra)
         return str(uri)
 
     @lightning_invoice.validator

electrum/util.py

@@ -942,6 +942,7 @@ def parse_URI(uri: str, on_pr: Callable = None, *, loop=None) -> dict:
     """Raises InvalidBitcoinURI on malformed URI."""
     from . import bitcoin
     from .bitcoin import COIN, TOTAL_COIN_SUPPLY_LIMIT_IN_BTC
+    from .lnaddr import lndecode
 
     if not isinstance(uri, str):
         raise InvalidBitcoinURI(f"expected string, not {repr(uri)}")
@@ -1004,6 +1005,17 @@ def parse_URI(uri: str, on_pr: Callable = None, *, loop=None) -> dict:
             out['sig'] = bh2u(bitcoin.base_decode(out['sig'], base=58))
         except Exception as e:
             raise InvalidBitcoinURI(f"failed to parse 'sig' field: {repr(e)}") from e
+    if 'lightning' in out:
+        try:
+            lnaddr = lndecode(out['lightning'])
+            amount_sat = out.get('amount')
+            if amount:
+                assert int(lnaddr.get_amount_sat()) == amount_sat
+            address = out.get('address')
+            if address:
+                assert lnaddr.get_fallback_address() == address
+        except Exception as e:
+            raise InvalidBitcoinURI(f"Inconsistent lightning field: {repr(e)}") from e
 
     r = out.get('r')
     sig = out.get('sig')

electrum/wallet.py

@@ -2348,7 +2348,8 @@ class Abstract_Wallet(AddressSynchronizer, ABC):
         amount_sat = amount_sat or 0
         exp_delay = exp_delay or 0
         timestamp = int(time.time())
-        lightning_invoice = self.lnworker.add_request(amount_sat, message, exp_delay) if lightning else None
+        fallback_address = address if self.config.get('bolt11_fallback', True) else None
+        lightning_invoice = self.lnworker.add_request(amount_sat, message, exp_delay, fallback_address) if lightning else None
         outputs = [ PartialTxOutput.from_address_and_value(address, amount_sat)] if address else []
         height = self.get_local_height()
         req = Invoice(