lnurl: implement LNURL-withdraw

adds handling of lnurl-withdraw payment identifiers which allow users to
withdraw bitcoin from a service by scanning a qr code or pasting the
lnurl-w code as "sending" address.

electrum/gui/qml/components/LnurlWithdrawRequestDialog.qml

@@ -0,0 +1,161 @@
+import QtQuick
+import QtQuick.Layouts
+import QtQuick.Controls
+import QtQuick.Controls.Material
+
+import org.electrum 1.0
+
+import "controls"
+
+ElDialog {
+    id: dialog
+
+    title: qsTr('LNURL Withdraw request')
+    iconSource: '../../../icons/link.png'
+
+    property InvoiceParser invoiceParser
+
+    padding: 0
+
+    property int walletCanReceive: invoiceParser.wallet.lightningCanReceive.satsInt
+    property int providerMinWithdrawable: parseInt(invoiceParser.lnurlData['min_withdrawable_sat'])
+    property int providerMaxWithdrawable: parseInt(invoiceParser.lnurlData['max_withdrawable_sat'])
+    property int effectiveMinWithdrawable: Math.max(providerMinWithdrawable, 1)
+    property int effectiveMaxWithdrawable: Math.min(providerMaxWithdrawable, walletCanReceive)
+    property bool insufficientLiquidity: effectiveMinWithdrawable > walletCanReceive
+    property bool liquidityWarning: providerMaxWithdrawable > walletCanReceive
+
+    property bool amountValid: !dialog.insufficientLiquidity &&
+        amountBtc.textAsSats.satsInt >= dialog.effectiveMinWithdrawable &&
+        amountBtc.textAsSats.satsInt <= dialog.effectiveMaxWithdrawable
+    property bool valid: amountValid
+
+    ColumnLayout {
+        width: parent.width
+
+        GridLayout {
+            id: rootLayout
+            columns: 2
+
+            Layout.fillWidth: true
+            Layout.leftMargin: constants.paddingLarge
+            Layout.rightMargin: constants.paddingLarge
+            Layout.bottomMargin: constants.paddingLarge
+
+            InfoTextArea {
+                Layout.columnSpan: 2
+                Layout.fillWidth: true
+                compact: true
+                visible: dialog.insufficientLiquidity
+                text: qsTr('Too little incoming liquidity to satisfy this withdrawal request.')
+                          + '\n\n'
+                          + qsTr('Can receive: %1')
+                            .arg(Config.formatSats(dialog.walletCanReceive) + ' ' + Config.baseUnit)
+                          + '\n'
+                          + qsTr('Minimum withdrawal amount: %1')
+                            .arg(Config.formatSats(dialog.providerMinWithdrawable) + ' ' + Config.baseUnit)
+                          + '\n\n'
+                          + qsTr('Do a submarine swap in the \'Channels\' tab to get more incoming liquidity.')
+                iconStyle: InfoTextArea.IconStyle.Error
+            }
+
+            InfoTextArea {
+                Layout.columnSpan: 2
+                Layout.fillWidth: true
+                compact: true
+                visible: !dialog.insufficientLiquidity && dialog.providerMinWithdrawable != dialog.providerMaxWithdrawable
+                text: qsTr('Amount must be between %1 and %2 %3')
+                .arg(Config.formatSats(dialog.effectiveMinWithdrawable))
+                .arg(Config.formatSats(dialog.effectiveMaxWithdrawable))
+                .arg(Config.baseUnit)
+            }
+
+            InfoTextArea {
+                Layout.columnSpan: 2
+                Layout.fillWidth: true
+                compact: true
+                visible: dialog.liquidityWarning && !dialog.insufficientLiquidity
+                text: qsTr('The maximum withdrawable amount (%1) is larger than what your channels can receive (%2).')
+                            .arg(Config.formatSats(dialog.providerMaxWithdrawable) + ' ' + Config.baseUnit)
+                            .arg(Config.formatSats(dialog.walletCanReceive) + ' ' + Config.baseUnit)
+                        + ' '
+                        + qsTr('You may need to do a submarine swap to increase your incoming liquidity.')
+                iconStyle: InfoTextArea.IconStyle.Warn
+            }
+
+            Label {
+                text: qsTr('Provider')
+                color: Material.accentColor
+            }
+            Label {
+                Layout.fillWidth: true
+                text: invoiceParser.lnurlData['domain']
+            }
+            Label {
+                text: qsTr('Description')
+                color: Material.accentColor
+                visible: invoiceParser.lnurlData['default_description']
+            }
+            Label {
+                Layout.fillWidth: true
+                text: invoiceParser.lnurlData['default_description']
+                visible: invoiceParser.lnurlData['default_description']
+                wrapMode: Text.Wrap
+            }
+
+            Label {
+                text: qsTr('Amount')
+                color: Material.accentColor
+            }
+
+            RowLayout {
+                Layout.fillWidth: true
+                BtcField {
+                    id: amountBtc
+                    Layout.preferredWidth: rootLayout.width / 3
+                    text: Config.formatSatsForEditing(dialog.effectiveMaxWithdrawable)
+                    enabled: !dialog.insufficientLiquidity && (dialog.providerMinWithdrawable != dialog.providerMaxWithdrawable)
+                    color: Material.foreground // override gray-out on disabled
+                    fiatfield: amountFiat
+                    onTextAsSatsChanged: {
+                        invoiceParser.amountOverride = textAsSats
+                    }
+                }
+                Label {
+                    text: Config.baseUnit
+                    color: Material.accentColor
+                }
+            }
+
+            Item { visible: Daemon.fx.enabled; Layout.preferredWidth: 1; Layout.preferredHeight: 1 }
+
+            RowLayout {
+                visible: Daemon.fx.enabled
+                FiatField {
+                    id: amountFiat
+                    Layout.preferredWidth: rootLayout.width / 3
+                    btcfield: amountBtc
+                    enabled: !dialog.insufficientLiquidity && (dialog.providerMinWithdrawable != dialog.providerMaxWithdrawable)
+                    color: Material.foreground
+                }
+                Label {
+                    text: Daemon.fx.fiatCurrency
+                    color: Material.accentColor
+                }
+            }
+        }
+
+        FlatButton {
+            Layout.topMargin: constants.paddingLarge
+            Layout.fillWidth: true
+            text: qsTr('Withdraw...')
+            icon.source: '../../icons/confirmed.png'
+            enabled: valid
+            onClicked: {
+                invoiceParser.lnurlRequestWithdrawal()
+                dialog.close()
+            }
+        }
+    }
+
+}

electrum/gui/qml/components/SendDialog.qml

@@ -57,8 +57,8 @@ ElDialog {
             Layout.fillHeight: true
 
             hint: Daemon.currentWallet.isLightning
-                ? qsTr('Scan an Invoice, an Address, an LNURL-pay, a PSBT or a Channel Backup')
-                : qsTr('Scan an Invoice, an Address, an LNURL-pay or a PSBT')
+                ? qsTr('Scan an Invoice, an Address, an LNURL, a PSBT or a Channel Backup')
+                : qsTr('Scan an Invoice, an Address, an LNURL or a PSBT')
 
             onFoundText: (data) => {
                 dialog.dispatch(data)

electrum/gui/qml/components/WalletMainView.qml

@@ -44,8 +44,8 @@ Item {
         // Android based send dialog if on android
         var scanner = app.scanDialog.createObject(mainView, {
             hint: Daemon.currentWallet.isLightning
-                ? qsTr('Scan an Invoice, an Address, an LNURL-pay, a PSBT or a Channel Backup')
-                : qsTr('Scan an Invoice, an Address, an LNURL-pay or a PSBT')
+                ? qsTr('Scan an Invoice, an Address, an LNURL, a PSBT or a Channel Backup')
+                : qsTr('Scan an Invoice, an Address, an LNURL or a PSBT')
         })
         scanner.onFoundText.connect(function(data) {
             data = data.trim()
@@ -423,9 +423,18 @@ Item {
 
         onLnurlRetrieved: {
             closeSendDialog()
-            var dialog = lnurlPayDialog.createObject(app, {
-                invoiceParser: invoiceParser
-            })
+            if (invoiceParser.invoiceType === Invoice.Type.LNURLPayRequest) {
+                var dialog = lnurlPayDialog.createObject(app, {
+                    invoiceParser: invoiceParser
+                })
+            } else if (invoiceParser.invoiceType === Invoice.Type.LNURLWithdrawRequest) {
+                var dialog = lnurlWithdrawDialog.createObject(app, {
+                    invoiceParser: invoiceParser
+                })
+            } else {
+                console.log("Unsupported LNURL type:", invoiceParser.invoiceType)
+                return
+            }
             dialog.open()
         }
         onLnurlError: (code, message) => {
@@ -739,6 +748,16 @@ Item {
         }
     }
 
+    Component {
+        id: lnurlWithdrawDialog
+        LnurlWithdrawRequestDialog {
+            width: parent.width * 0.9
+            anchors.centerIn: parent
+
+            onClosed: destroy()
+        }
+    }
+
     Component {
         id: otpDialog
         OtpDialog {

electrum/gui/qml/qeinvoice.py

@@ -14,6 +14,7 @@ from electrum.invoices import (
 )
 from electrum.transaction import PartialTxOutput, TxOutput
 from electrum.lnutil import format_short_channel_id
+from electrum.lnurl import LNURLData, LNURL3Data, LNURL6Data, request_lnurl_withdraw_callback, LNURLError
 from electrum.bitcoin import COIN, address_to_script
 from electrum.paymentrequest import PaymentRequest
 from electrum.payment_identifier import PaymentIdentifier, PaymentIdentifierState, PaymentIdentifierType
@@ -33,6 +34,7 @@ class QEInvoice(QObject, QtEventListener):
         OnchainInvoice = 0
         LightningInvoice = 1
         LNURLPayRequest = 2
+        LNURLWithdrawRequest = 3
 
     @pyqtEnum
     class Status(IntEnum):
@@ -478,7 +480,7 @@ class QEInvoiceParser(QEInvoice):
 
     @pyqtProperty(bool, notify=lnurlRetrieved)
     def isLnurlPay(self):
-        return self._lnurlData is not None
+        return self._lnurlData is not None and self.invoiceType == QEInvoice.Type.LNURLPayRequest
 
     @pyqtProperty(bool, notify=busyChanged)
     def busy(self):
@@ -513,6 +515,12 @@ class QEInvoiceParser(QEInvoice):
         self._effectiveInvoice = None
         self.invoiceChanged.emit()
 
+    def setValidLNURLWithdrawRequest(self):
+        self._logger.debug('setValidLNURLWithdrawRequest')
+        self.setInvoiceType(QEInvoice.Type.LNURLWithdrawRequest)
+        self._effectiveInvoice = None
+        self.invoiceChanged.emit()
+
     def create_onchain_invoice(self, outputs, message, payment_request, uri):
         return self._wallet.wallet.create_invoice(
             outputs=outputs,
@@ -543,7 +551,7 @@ class QEInvoiceParser(QEInvoice):
         self._pi = PaymentIdentifier(self._wallet.wallet, recipient)
         if not self._pi.is_valid() or self._pi.type not in [PaymentIdentifierType.SPK, PaymentIdentifierType.BIP21,
                                                             PaymentIdentifierType.BIP70, PaymentIdentifierType.BOLT11,
-                                                            PaymentIdentifierType.LNURLP,
+                                                            PaymentIdentifierType.LNURL,
                                                             PaymentIdentifierType.EMAILLIKE,
                                                             PaymentIdentifierType.DOMAINLIKE]:
             self.validationError.emit('unknown', _('Unknown invoice'))
@@ -562,7 +570,11 @@ class QEInvoiceParser(QEInvoice):
             self.resolve_pi()
             return
 
-        if self._pi.type in [PaymentIdentifierType.LNURLP, PaymentIdentifierType.LNADDR]:
+        if self._pi.type in [
+            PaymentIdentifierType.LNURLP,
+            PaymentIdentifierType.LNURLW,
+            PaymentIdentifierType.LNADDR,
+        ]:
             self.on_lnurl(self._pi.lnurl_data)
             return
 
@@ -622,7 +634,7 @@ class QEInvoiceParser(QEInvoice):
             if pi.is_error():
                 if pi.type in [PaymentIdentifierType.EMAILLIKE, PaymentIdentifierType.DOMAINLIKE]:
                     msg = _('Could not resolve address')
-                elif pi.type == PaymentIdentifierType.LNURLP:
+                elif pi.type == PaymentIdentifierType.LNURL:
                     msg = _('Could not resolve LNURL') + "\n\n" + pi.get_error()
                 elif pi.type == PaymentIdentifierType.BIP70:
                     msg = _('Could not resolve BIP70 payment request: {}').format(pi.error)
@@ -637,19 +649,32 @@ class QEInvoiceParser(QEInvoice):
 
         self._pi.resolve(on_finished=on_finished)
 
-    def on_lnurl(self, lnurldata):
+    def on_lnurl(self, lnurldata: LNURLData):
         self._logger.debug('on_lnurl')
         self._logger.debug(f'{repr(lnurldata)}')
 
-        self._lnurlData = {
-            'domain': urlparse(lnurldata.callback_url).netloc,
-            'callback_url': lnurldata.callback_url,
-            'min_sendable_sat': lnurldata.min_sendable_sat,
-            'max_sendable_sat': lnurldata.max_sendable_sat,
-            'metadata_plaintext': lnurldata.metadata_plaintext,
-            'comment_allowed': lnurldata.comment_allowed
-        }
-        self.setValidLNURLPayRequest()
+        if isinstance(lnurldata, LNURL6Data):
+            self._lnurlData = {
+                'domain': urlparse(lnurldata.callback_url).netloc,
+                'callback_url': lnurldata.callback_url,
+                'min_sendable_sat': lnurldata.min_sendable_sat,
+                'max_sendable_sat': lnurldata.max_sendable_sat,
+                'metadata_plaintext': lnurldata.metadata_plaintext,
+                'comment_allowed': lnurldata.comment_allowed,
+            }
+            self.setValidLNURLPayRequest()
+        elif isinstance(lnurldata, LNURL3Data):
+            self._lnurlData = {
+                'domain': urlparse(lnurldata.callback_url).netloc,
+                'callback_url': lnurldata.callback_url,
+                'min_withdrawable_sat': lnurldata.min_withdrawable_sat,
+                'max_withdrawable_sat': lnurldata.max_withdrawable_sat,
+                'default_description': lnurldata.default_description,
+                'k1': lnurldata.k1,
+            }
+            self.setValidLNURLWithdrawRequest()
+        else:
+            raise NotImplementedError(f"Invalid lnurl type in on_lnurl {lnurldata=}")
         self.lnurlRetrieved.emit()
 
     @pyqtSlot()
@@ -657,6 +682,7 @@ class QEInvoiceParser(QEInvoice):
     def lnurlGetInvoice(self, comment=None):
         assert self._lnurlData
         assert self._pi.need_finalize()
+        assert self.invoiceType == QEInvoice.Type.LNURLPayRequest
         self._logger.debug(f'{repr(self._lnurlData)}')
 
         amount = self.amountOverride.satsInt
@@ -681,6 +707,54 @@ class QEInvoiceParser(QEInvoice):
 
         self._pi.finalize(amount_sat=amount, comment=comment, on_finished=on_finished)
 
+    @pyqtSlot()
+    def lnurlRequestWithdrawal(self):
+        assert self._lnurlData
+        assert self.invoiceType == QEInvoice.Type.LNURLWithdrawRequest
+        self._logger.debug(f'{repr(self._lnurlData)}')
+
+        amount_sat = self.amountOverride.satsInt
+
+        try:
+            key = self.wallet.wallet.create_request(
+                amount_sat=amount_sat,
+                message=self._lnurlData.get('default_description', ''),
+                exp_delay=120,
+                address=None,
+            )
+            req = self.wallet.wallet.get_request(key)
+            _lnaddr, b11_invoice = self.wallet.wallet.lnworker.get_bolt11_invoice(
+                payment_hash=req.payment_hash,
+                amount_msat=req.get_amount_msat(),
+                message=req.get_message(),
+                expiry=req.exp,
+                fallback_address=None
+            )
+        except Exception as e:
+            self._logger.exception('')
+            self.lnurlError.emit(
+                'lnurl',
+                _("Failed to create payment request for withdrawal: {}").format(str(e))
+            )
+            return
+
+        self._busy = True
+        self.busyChanged.emit()
+
+        coro = request_lnurl_withdraw_callback(
+            callback_url=self._lnurlData['callback_url'],
+            k1=self._lnurlData['k1'],
+            bolt_11=b11_invoice,
+        )
+        try:
+            Network.run_from_another_thread(coro)
+        except LNURLError as e:
+            self.lnurlError.emit('lnurl', str(e))
+
+        self._busy = False
+        self.busyChanged.emit()
+
+
     def on_lnurl_invoice(self, orig_amount, invoice):
         self._logger.debug('on_lnurl_invoice')
         self._logger.debug(f'{repr(invoice)}')

electrum/gui/qt/send_tab.py

@@ -4,6 +4,7 @@
 
 from decimal import Decimal
 from typing import Optional, TYPE_CHECKING, Sequence, List, Callable, Union, Mapping
+import urllib.parse
 
 from PyQt6.QtCore import pyqtSignal, QPoint, Qt
 from PyQt6.QtWidgets import (QLabel, QVBoxLayout, QGridLayout, QHBoxLayout,
@@ -20,15 +21,18 @@ from electrum.util import (
 from electrum.invoices import PR_PAID, Invoice, PR_BROADCASTING, PR_BROADCAST
 from electrum.transaction import Transaction, PartialTxInput, PartialTxOutput
 from electrum.network import TxBroadcastError, BestEffortRequestFailed
-from electrum.payment_identifier import (PaymentIdentifierType, PaymentIdentifier, invoice_from_payment_identifier,
-                                         payment_identifier_from_invoice)
+from electrum.payment_identifier import (PaymentIdentifierType, PaymentIdentifier,
+                                         invoice_from_payment_identifier,
+                                         payment_identifier_from_invoice, PaymentIdentifierState)
 from electrum.submarine_swaps import SwapServerError
 from electrum.fee_policy import FeePolicy, FixedFeePolicy
+from electrum.lnurl import LNURL3Data, request_lnurl_withdraw_callback, LNURLError
 
 from .amountedit import AmountEdit, BTCAmountEdit, SizedFreezableLineEdit
 from .paytoedit import InvalidPaymentIdentifier
 from .util import (WaitingDialog, HelpLabel, MessageBoxMixin, EnterButton, char_width_in_lineedit,
-                   get_icon_camera, read_QIcon, ColorScheme, IconLabel, Spinner, add_input_actions_to_context_menu)
+                   get_icon_camera, read_QIcon, ColorScheme, IconLabel, Spinner, Buttons, WWLabel,
+                   add_input_actions_to_context_menu, WindowModalDialog, OkButton, CancelButton)
 from .invoice_list import InvoiceList
 
 if TYPE_CHECKING:
@@ -435,7 +439,8 @@ class SendTab(QWidget, MessageBoxMixin, Logger):
             self.send_button.setEnabled(False)
             return
 
-        lock_recipient = pi.type in [PaymentIdentifierType.LNURLP, PaymentIdentifierType.LNADDR,
+        lock_recipient = pi.type in [PaymentIdentifierType.LNURL, PaymentIdentifierType.LNURLW,
+                                     PaymentIdentifierType.LNURLP, PaymentIdentifierType.LNADDR,
                                      PaymentIdentifierType.OPENALIAS, PaymentIdentifierType.BIP70,
                                      PaymentIdentifierType.BIP21, PaymentIdentifierType.BOLT11] and not pi.need_resolve()
         lock_amount = pi.is_amount_locked()
@@ -504,6 +509,13 @@ class SendTab(QWidget, MessageBoxMixin, Logger):
             self.show_error(pi.error)
             self.do_clear()
             return
+        if pi.type == PaymentIdentifierType.LNURLW:
+            assert pi.state == PaymentIdentifierState.LNURLW_FINALIZE, \
+                f"Detected LNURLW but not ready to finalize? {pi=}"
+            self.do_clear()
+            self.request_lnurl_withdraw_dialog(pi.lnurl_data)
+            return
+
         # if openalias add openalias to contacts
         if pi.type == PaymentIdentifierType.OPENALIAS:
             key = pi.emaillike if pi.emaillike else pi.domainlike
@@ -830,3 +842,145 @@ class SendTab(QWidget, MessageBoxMixin, Logger):
             else:
                 total += output.value
         self.amount_e.setAmount(total if outputs else None)
+
+    def request_lnurl_withdraw_dialog(self, lnurl_data: LNURL3Data):
+        if not self.wallet.has_lightning():
+            self.show_error(
+                _("Cannot request lightning withdrawal, wallet has no lightning channels.")
+            )
+            return
+
+        dialog = WindowModalDialog(self, _("Lightning Withdrawal"))
+        dialog.setMinimumWidth(400)
+
+        vbox = QVBoxLayout()
+        dialog.setLayout(vbox)
+        grid = QGridLayout()
+        grid.setSpacing(8)
+        grid.setColumnStretch(3, 1)  # Make the last column stretch
+
+        row = 0
+
+        # provider url
+        domain_label = QLabel(_("Provider") + ":")
+        domain_text = WWLabel(urllib.parse.urlparse(lnurl_data.callback_url).netloc)
+        grid.addWidget(domain_label, row, 0)
+        grid.addWidget(domain_text, row, 1, 1, 3)
+        row += 1
+
+        if lnurl_data.default_description:
+            desc_label = QLabel(_("Description") + ":")
+            desc_text = WWLabel(lnurl_data.default_description)
+            grid.addWidget(desc_label, row, 0)
+            grid.addWidget(desc_text, row, 1, 1, 3)
+            row += 1
+
+        min_amount = max(lnurl_data.min_withdrawable_sat, 1)
+        max_amount = min(
+            lnurl_data.max_withdrawable_sat,
+            int(self.wallet.lnworker.num_sats_can_receive())
+        )
+        min_text = self.format_amount_and_units(lnurl_data.min_withdrawable_sat)
+        if min_amount > int(self.wallet.lnworker.num_sats_can_receive()):
+            self.show_error("".join([
+                _("Too little incoming liquidity to satisfy this withdrawal request."), "\n\n",
+                _("Can receive: {}").format(
+                    self.format_amount_and_units(self.wallet.lnworker.num_sats_can_receive()),
+                ), "\n",
+                _("Minimum withdrawal amount: {}").format(min_text), "\n\n",
+                _("Do a submarine swap in the 'Channels' tab to get more incoming liquidity.")
+            ]))
+            return
+
+        is_fixed_amount = lnurl_data.min_withdrawable_sat == lnurl_data.max_withdrawable_sat
+
+        # Range information (only for non-fixed amounts)
+        if not is_fixed_amount:
+            range_label_text = QLabel(_("Range") + ":")
+            range_value = QLabel("{} - {}".format(
+                min_text,
+                self.format_amount_and_units(lnurl_data.max_withdrawable_sat)
+            ))
+            grid.addWidget(range_label_text, row, 0)
+            grid.addWidget(range_value, row, 1, 1, 2)
+            row += 1
+
+        # Amount section
+        amount_label = QLabel(_("Amount") + ":")
+        amount_edit = BTCAmountEdit(self.window.get_decimal_point, max_amount=max_amount)
+        amount_edit.setAmount(max_amount)
+        grid.addWidget(amount_label, row, 0)
+        grid.addWidget(amount_edit, row, 1)
+
+        if is_fixed_amount:
+            # Fixed amount, just show the amount
+            amount_edit.setDisabled(True)
+        else:
+            # Range, show max button
+            max_button = EnterButton(_("Max"), lambda: amount_edit.setAmount(max_amount))
+            btn_width = 10 * char_width_in_lineedit()
+            max_button.setFixedWidth(btn_width)
+            grid.addWidget(max_button, row, 2)
+
+        row += 1
+
+        # Warning for insufficient liquidity
+        if lnurl_data.max_withdrawable_sat > int(self.wallet.lnworker.num_sats_can_receive()):
+            warning_text = WWLabel(
+                _("The maximum withdrawable amount is larger than what your channels can receive. "
+                  "You may need to do a submarine swap to increase your incoming liquidity.")
+            )
+            warning_text.setStyleSheet("color: orange;")
+            grid.addWidget(warning_text, row, 0, 1, 4)
+            row += 1
+
+        vbox.addLayout(grid)
+
+        # Buttons
+        request_button = OkButton(dialog, _("Request Withdrawal"))
+        cancel_button = CancelButton(dialog)
+        vbox.addLayout(Buttons(cancel_button, request_button))
+
+        # Show dialog and handle result
+        if dialog.exec():
+            if is_fixed_amount:
+                amount_sat = lnurl_data.max_withdrawable_sat
+            else:
+                amount_sat = amount_edit.get_amount()
+                if not amount_sat or not (min_amount <= int(amount_sat) <= max_amount):
+                    self.show_error(_("Enter a valid amount. You entered: {}").format(amount_sat))
+                    return
+        else:
+            return
+
+        try:
+            key = self.wallet.create_request(
+                amount_sat=amount_sat,
+                message=lnurl_data.default_description,
+                exp_delay=120,
+                address=None,
+            )
+            req = self.wallet.get_request(key)
+            _lnaddr, b11_invoice = self.wallet.lnworker.get_bolt11_invoice(
+                payment_hash=req.payment_hash,
+                amount_msat=req.get_amount_msat(),
+                message=req.get_message(),
+                expiry=req.exp,
+                fallback_address=None
+            )
+        except Exception as e:
+            self.logger.exception('')
+            self.show_error(
+                f"{_('Failed to create payment request for withdrawal')}: {str(e)}"
+            )
+            return
+
+        coro = request_lnurl_withdraw_callback(
+            callback_url=lnurl_data.callback_url,
+            k1=lnurl_data.k1,
+            bolt_11=b11_invoice
+        )
+        try:
+            self.window.run_coroutine_dialog(coro, _("Requesting lightning withdrawal..."))
+        except LNURLError as e:
+            self.show_error(f"{_('Failed to request withdrawal')}:\n{str(e)}")

electrum/lnurl.py

@@ -9,7 +9,6 @@ import re
 import urllib.parse
 
 import aiohttp.client_exceptions
-from aiohttp import ClientResponse
 
 from electrum import segwit_addr
 from electrum.segwit_addr import bech32_decode, Encoding, convertbits, bech32_encode
@@ -17,15 +16,16 @@ from electrum.lnaddr import LnDecodeException, LnEncodeException
 from electrum.network import Network
 from electrum.logging import get_logger
 
-if TYPE_CHECKING:
-    from collections.abc import Coroutine
-
 
 _logger = get_logger(__name__)
 
 
 class LNURLError(Exception):
-    pass
+    def __init__(self, message="", *args):
+        # error messages are returned by the LNURL server, some services could try to trick
+        # users into doing something by sending a malicious error message
+        modified_message = f"[DO NOT TRUST THIS MESSAGE]:\n{message}"
+        super().__init__(modified_message, *args)
 
 
 def decode_lnurl(lnurl: str) -> str:
@@ -68,6 +68,19 @@ def _is_url_safe_enough_for_lnurl(url: str) -> bool:
     return False
 
 
+def _parse_lnurl_response_callback_url(lnurl_response: dict) -> str:
+    try:
+        callback_url = lnurl_response['callback']
+    except KeyError as e:
+        raise LNURLError(f"Missing 'callback' field in lnurl response.") from e
+    if not _is_url_safe_enough_for_lnurl(callback_url):
+        raise LNURLError(
+            f"This lnurl callback_url looks unsafe. It must use 'https://' or '.onion' (found: {callback_url[:10]}...)")
+    return callback_url
+
+
+# payRequest
+# https://github.com/lnurl/luds/blob/227f850b701e9ba893c080103c683273e2feb521/06.md
 class LNURL6Data(NamedTuple):
     callback_url: str
     max_sendable_sat: int
@@ -76,6 +89,23 @@ class LNURL6Data(NamedTuple):
     comment_allowed: int
     #tag: str = "payRequest"
 
+# withdrawRequest
+# https://github.com/lnurl/luds/blob/227f850b701e9ba893c080103c683273e2feb521/03.md
+class LNURL3Data(NamedTuple):
+    # The URL which LN SERVICE would accept a withdrawal Lightning invoice as query parameter
+    callback_url: str
+    # Random or non-random string to identify the user's LN WALLET when using the callback URL
+    k1: str
+    # A default withdrawal invoice description
+    default_description: str
+    # Min amount the user can withdraw from LN SERVICE, or 0
+    min_withdrawable_sat: int
+    # Max amount the user can withdraw from LN SERVICE,
+    # or equal to minWithdrawable if the user has no choice over the amounts
+    max_withdrawable_sat: int
+
+LNURLData = LNURL6Data | LNURL3Data
+
 
 async def _request_lnurl(url: str) -> dict:
     """Requests payment data from a lnurl."""
@@ -98,37 +128,30 @@ async def _request_lnurl(url: str) -> dict:
     return response
 
 
-async def request_lnurl(url: str) -> LNURL6Data:
-    lnurl_dict = await _request_lnurl(url)
-    tag = lnurl_dict.get('tag')
-    if tag != 'payRequest':  # only LNURL6 is handled atm
-        raise LNURLError(f"Unknown subtype of lnurl. tag={tag}")
+def _parse_lnurl6_response(lnurl_response: dict) -> LNURL6Data:
     # parse lnurl6 "metadata"
     metadata_plaintext = ""
     try:
-        metadata_raw = lnurl_dict["metadata"]
+        metadata_raw = lnurl_response["metadata"]
         metadata = json.loads(metadata_raw)
         for m in metadata:
             if m[0] == 'text/plain':
                 metadata_plaintext = str(m[1])
     except Exception as e:
-        raise LNURLError(f"Missing or malformed 'metadata' field in lnurl6 response. exc: {e!r}") from e
+        raise LNURLError(
+            f"Missing or malformed 'metadata' field in lnurl6 response. exc: {e!r}") from e
     # parse lnurl6 "callback"
-    try:
-        callback_url = lnurl_dict['callback']
-    except KeyError as e:
-        raise LNURLError(f"Missing 'callback' field in lnurl6 response.") from e
-    if not _is_url_safe_enough_for_lnurl(callback_url):
-        raise LNURLError(f"This lnurl callback_url looks unsafe. It must use 'https://' or '.onion' (found: {callback_url[:10]}...)")
+    callback_url = _parse_lnurl_response_callback_url(lnurl_response)
     # parse lnurl6 "minSendable"/"maxSendable"
     try:
-        max_sendable_sat = int(lnurl_dict['maxSendable']) // 1000
-        min_sendable_sat = int(lnurl_dict['minSendable']) // 1000
+        max_sendable_sat = int(lnurl_response['maxSendable']) // 1000
+        min_sendable_sat = int(lnurl_response['minSendable']) // 1000
     except Exception as e:
-        raise LNURLError(f"Missing or malformed 'minSendable'/'maxSendable' field in lnurl6 response. {e=!r}") from e
+        raise LNURLError(
+            f"Missing or malformed 'minSendable'/'maxSendable' field in lnurl6 response. {e=!r}") from e
     # parse lnurl6 "commentAllowed" (optional, described in lnurl-12)
     try:
-        comment_allowed = int(lnurl_dict['commentAllowed']) if 'commentAllowed' in lnurl_dict else 0
+        comment_allowed = int(lnurl_response['commentAllowed']) if 'commentAllowed' in lnurl_response else 0
     except Exception as e:
         raise LNURLError(f"Malformed 'commentAllowed' field in lnurl6 response. {e=!r}") from e
     data = LNURL6Data(
@@ -141,14 +164,59 @@ async def request_lnurl(url: str) -> LNURL6Data:
     return data
 
 
-async def try_resolve_lnurl(lnurl: Optional[str]) -> Optional[LNURL6Data]:
+def _parse_lnurl3_response(lnurl_response: dict) -> LNURL3Data:
+    """Parses the server response received when requesting a LNURL-withdraw (lud3) request"""
+    callback_url = _parse_lnurl_response_callback_url(lnurl_response)
+    if not (k1 := lnurl_response.get('k1')):
+        raise LNURLError(f"Missing k1 value in LNURL3 response: {lnurl_response=}")
+    default_description = lnurl_response.get('defaultDescription', '')
+    try:
+        min_withdrawable_sat = int(lnurl_response['minWithdrawable']) // 1000
+        max_withdrawable_sat = int(lnurl_response['maxWithdrawable']) // 1000
+        assert max_withdrawable_sat >= min_withdrawable_sat, f"Invalid amounts: max < min amount"
+        assert max_withdrawable_sat > 0, f"Invalid max amount: {max_withdrawable_sat} sat"
+    except Exception as e:
+        raise LNURLError(
+            f"Missing or malformed 'minWithdrawable'/'minWithdrawable' field in lnurl3 response. {e=!r}") from e
+    return LNURL3Data(
+        callback_url=callback_url,
+        k1=k1,
+        default_description=default_description,
+        min_withdrawable_sat=min_withdrawable_sat,
+        max_withdrawable_sat=max_withdrawable_sat,
+    )
+
+
+async def request_lnurl(url: str) -> LNURLData:
+    lnurl_dict = await _request_lnurl(url)
+    tag = lnurl_dict.get('tag')
+    if tag == 'payRequest':  # only LNURL6 is handled atm
+        return _parse_lnurl6_response(lnurl_dict)
+    elif tag == 'withdrawRequest':
+        return _parse_lnurl3_response(lnurl_dict)
+    raise LNURLError(f"Unknown subtype of lnurl. tag={tag}")
+
+
+async def try_resolve_lnurlpay(lnurl: Optional[str]) -> Optional[LNURL6Data]:
     if lnurl:
         try:
-            return await request_lnurl(lnurl)
+            result = await request_lnurl(lnurl)
+            assert isinstance(result, LNURL6Data), f"lnurl result is not LNURL-pay response: {result=}"
+            return result
         except Exception as request_error:
             _logger.debug(f"Error resolving lnurl: {request_error!r}")
     return None
 
+async def request_lnurl_withdraw_callback(callback_url: str, k1: str, bolt_11: str) -> None:
+    assert bolt_11
+    params = {
+        "k1": k1,
+        "pr": bolt_11,
+    }
+    await callback_lnurl(
+        url=callback_url,
+        params=params
+    )
 
 async def callback_lnurl(url: str, params: dict) -> dict:
     """Requests an invoice from a lnurl supporting server."""

electrum/lnworker.py

@@ -2258,7 +2258,7 @@ class LNWallet(LNWorker):
         timestamp = int(time.time())
         needs_jit: bool = self.receive_requires_jit_channel(amount_msat)
         routing_hints = self.calc_routing_hints_for_invoice(amount_msat, channels=channels, needs_jit=needs_jit)
-        self.logger.info(f"creating bolt11 invoice with routing_hints: {routing_hints}, jit: {needs_jit}, sat: {amount_msat or 0 // 1000}")
+        self.logger.info(f"creating bolt11 invoice with routing_hints: {routing_hints}, jit: {needs_jit}, sat: {(amount_msat or 0) // 1000}")
         invoice_features = self.features.for_invoice()
         if not self.uses_trampoline():
             invoice_features &= ~ LnFeatures.OPTION_TRAMPOLINE_ROUTING_OPT_ELECTRUM

electrum/payment_identifier.py

@@ -14,8 +14,9 @@ from .logging import Logger
 from .util import parse_max_spend, InvoiceError
 from .util import get_asyncio_loop, log_exceptions
 from .transaction import PartialTxOutput
-from .lnurl import (decode_lnurl, request_lnurl, callback_lnurl, LNURLError, lightning_address_to_url,
-                    try_resolve_lnurl)
+from .lnurl import (decode_lnurl, request_lnurl, callback_lnurl, LNURLError,
+                    lightning_address_to_url, try_resolve_lnurlpay, LNURL6Data,
+                    LNURL3Data, LNURLData)
 from .bitcoin import opcodes, construct_script
 from .lnaddr import LnInvoiceException
 from .lnutil import IncompatibleOrInsaneFeatures
@@ -60,10 +61,11 @@ class PaymentIdentifierState(IntEnum):
                             # of the channels Electrum supports (on-chain, lightning)
     NEED_RESOLVE = 3        # PI contains a recognized destination format, but needs an online resolve step
     LNURLP_FINALIZE = 4     # PI contains a resolved LNURLp, but needs amount and comment to resolve to a bolt11
-    MERCHANT_NOTIFY = 5     # PI contains a valid payment request and on-chain destination. It should notify
+    LNURLW_FINALIZE = 5     # PI contains resolved LNURLw, user needs to enter amount and initiate withdraw
+    MERCHANT_NOTIFY = 6     # PI contains a valid payment request and on-chain destination. It should notify
                             # the merchant payment processor of the tx after on-chain broadcast,
                             # and supply a refund address (bip70)
-    MERCHANT_ACK = 6        # PI notified merchant. nothing to be done.
+    MERCHANT_ACK = 7        # PI notified merchant. nothing to be done.
     ERROR = 50              # generic error
     NOT_FOUND = 51          # PI contains a recognized destination format, but resolve step was unsuccessful
     MERCHANT_ERROR = 52     # PI failed notifying the merchant after broadcasting onchain TX
@@ -77,11 +79,13 @@ class PaymentIdentifierType(IntEnum):
     BIP70 = 3
     MULTILINE = 4
     BOLT11 = 5
-    LNURLP = 6
-    EMAILLIKE = 7
-    OPENALIAS = 8
-    LNADDR = 9
-    DOMAINLIKE = 10
+    LNURL = 6  # before the resolve it's unknown if pi is LNURLP or LNURLW
+    LNURLP = 7
+    LNURLW = 8
+    EMAILLIKE = 9
+    OPENALIAS = 10
+    LNADDR = 11
+    DOMAINLIKE = 12
 
 
 class FieldsForGUI(NamedTuple):
@@ -133,8 +137,8 @@ class PaymentIdentifier(Logger):
         self.merchant_ack_status = None
         self.merchant_ack_message = None
         #
-        self.lnurl = None
-        self.lnurl_data = None
+        self.lnurl = None  # type: Optional[str]
+        self.lnurl_data = None # type: Optional[LNURLData]
 
         self.parse(text)
 
@@ -223,7 +227,7 @@ class PaymentIdentifier(Logger):
                 self.set_state(PaymentIdentifierState.AVAILABLE)
         elif invoice_or_lnurl := maybe_extract_lightning_payment_identifier(text):
             if invoice_or_lnurl.startswith('lnurl'):
-                self._type = PaymentIdentifierType.LNURLP
+                self._type = PaymentIdentifierType.LNURL
                 try:
                     self.lnurl = decode_lnurl(invoice_or_lnurl)
                     self.set_state(PaymentIdentifierState.NEED_RESOLVE)
@@ -317,7 +321,7 @@ class PaymentIdentifier(Logger):
 
                 # prefers lnurl over openalias if both are available
                 lnurl = lightning_address_to_url(self.emaillike) if self.emaillike else None
-                if lnurl is not None and (lnurl_result := await try_resolve_lnurl(lnurl)):
+                if lnurl is not None and (lnurl_result := await try_resolve_lnurlpay(lnurl)):
                     openalias_task.cancel()
                     self._type = PaymentIdentifierType.LNADDR
                     self.lnurl = lnurl
@@ -353,7 +357,14 @@ class PaymentIdentifier(Logger):
             elif self.lnurl:
                 data = await request_lnurl(self.lnurl)
                 self.lnurl_data = data
-                self.set_state(PaymentIdentifierState.LNURLP_FINALIZE)
+                if isinstance(data, LNURL6Data):
+                    self._type = PaymentIdentifierType.LNURLP
+                    self.set_state(PaymentIdentifierState.LNURLP_FINALIZE)
+                elif isinstance(data, LNURL3Data):
+                    self._type = PaymentIdentifierType.LNURLW
+                    self.set_state(PaymentIdentifierState.LNURLW_FINALIZE)
+                else:
+                    raise NotImplementedError(f"Invalid LNURL type? {data=}")
                 self.logger.debug(f'LNURL data: {data!r}')
             else:
                 self.set_state(PaymentIdentifierState.ERROR)
@@ -592,6 +603,7 @@ class PaymentIdentifier(Logger):
             recipient, amount, description = self._get_bolt11_fields()
 
         elif self.lnurl and self.lnurl_data:
+            assert isinstance(self.lnurl_data, LNURL6Data), f"{self.lnurl_data=}"
             domain = urllib.parse.urlparse(self.lnurl).netloc
             recipient = f"{self.lnurl_data.metadata_plaintext} <{domain}>"
             description = self.lnurl_data.metadata_plaintext

tests/test_lnurl.py

@@ -20,3 +20,85 @@ class TestLnurl(TestCase):
     def test_lightning_address_to_url(self):
         url = lnurl.lightning_address_to_url("mempool@jhoenicke.de")
         self.assertEqual("https://jhoenicke.de/.well-known/lnurlp/mempool", url)
+
+    def test_parse_lnurl3_response(self):
+        # Test successful parsing with all fields
+        sample_response = {
+            'callback': 'https://service.io/withdraw?sessionid=123',
+            'k1': 'abcdef1234567890',
+            'defaultDescription': 'Withdraw from service',
+            'minWithdrawable': 10_000_000,
+            'maxWithdrawable': 100_000_000,
+        }
+
+        result = lnurl._parse_lnurl3_response(sample_response)
+
+        self.assertEqual('https://service.io/withdraw?sessionid=123', result.callback_url)
+        self.assertEqual('abcdef1234567890', result.k1)
+        self.assertEqual('Withdraw from service', result.default_description)
+        self.assertEqual(10_000, result.min_withdrawable_sat)
+        self.assertEqual(100_000, result.max_withdrawable_sat)
+
+        # Test with .onion URL
+        onion_response = {
+            'callback': 'http://robosatsy56bwqn56qyadmcxkx767hnabg4mihxlmgyt6if5gnuxvzad.onion/withdraw?sessionid=123',
+            'k1': 'abcdef1234567890',
+            'minWithdrawable': 10_000_000,
+            'maxWithdrawable': 100_000_000
+        }
+
+        result = lnurl._parse_lnurl3_response(onion_response)
+        self.assertEqual('http://robosatsy56bwqn56qyadmcxkx767hnabg4mihxlmgyt6if5gnuxvzad.onion/withdraw?sessionid=123',
+                         result.callback_url)
+        self.assertEqual('', result.default_description)  # Missing defaultDescription uses empty string
+
+        # Test missing callback (should raise error)
+        no_callback_response = {
+            'k1': 'abcdef1234567890',
+            'minWithdrawable': 10_000_000,
+            'maxWithdrawable': 100_000_000
+        }
+
+        with self.assertRaises(lnurl.LNURLError):
+            lnurl._parse_lnurl3_response(no_callback_response)
+
+        # Test unsafe callback URL
+        unsafe_response = {
+            'callback': 'http://service.io/withdraw?sessionid=123',  # HTTP URL
+            'k1': 'abcdef1234567890',
+            'minWithdrawable': 10_000_000,
+            'maxWithdrawable': 100_000_000
+        }
+
+        with self.assertRaises(lnurl.LNURLError):
+            lnurl._parse_lnurl3_response(unsafe_response)
+
+        # Test missing k1 (should raise error)
+        no_k1_response = {
+            'callback': 'https://service.io/withdraw?sessionid=123',
+            'minWithdrawable': 10_000_000,
+            'maxWithdrawable': 100_000_000
+        }
+
+        with self.assertRaises(lnurl.LNURLError):
+            lnurl._parse_lnurl3_response(no_k1_response)
+
+        # Test missing withdrawable amounts (should raise error)
+        no_amounts_response = {
+            'callback': 'https://service.io/withdraw?sessionid=123',
+            'k1': 'abcdef1234567890',
+        }
+
+        with self.assertRaises(lnurl.LNURLError):
+            lnurl._parse_lnurl3_response(no_amounts_response)
+
+        # Test malformed withdrawable amounts (should raise error)
+        bad_amounts_response = {
+            'callback': 'https://service.io/withdraw?sessionid=123',
+            'k1': 'abcdef1234567890',
+            'minWithdrawable': 'this is not a number',
+            'maxWithdrawable': 100_000_000
+        }
+
+        with self.assertRaises(lnurl.LNURLError):
+            lnurl._parse_lnurl3_response(bad_amounts_response)