Merge pull request #7839 from SomberNight/202202_lnurl_2

add lnurl-pay (`LUD-06`) support

electrum/contacts.py

@@ -21,6 +21,8 @@
 # CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 # SOFTWARE.
 import re
+from typing import Optional, Tuple
+
 import dns
 import threading
 from dns.exception import DNSException
@@ -106,7 +108,7 @@ class Contacts(dict, Logger):
             t.daemon = True
             t.start()
 
-    def resolve_openalias(self, url):
+    def resolve_openalias(self, url: str) -> Optional[Tuple[str, str, bool]]:
         # support email-style addresses, per the OA standard
         url = url.replace('@', '.')
         try:

electrum/gui/kivy/main_window.py

@@ -18,7 +18,7 @@ from electrum.plugin import run_hook
 from electrum import util
 from electrum.util import (profiler, InvalidPassword, send_exception_to_crash_reporter,
                            format_satoshis, format_satoshis_plain, format_fee_satoshis,
-                           maybe_extract_bolt11_invoice, parse_max_spend)
+                           parse_max_spend)
 from electrum.util import EventListener, event_listener
 from electrum.invoices import PR_PAID, PR_FAILED, Invoice
 from electrum import blockchain
@@ -235,10 +235,6 @@ class ElectrumWindow(App, Logger, EventListener):
     def set_URI(self, uri):
         self.send_screen.set_URI(uri)
 
-    @switch_to_send_screen
-    def set_ln_invoice(self, invoice):
-        self.send_screen.set_ln_invoice(invoice)
-
     def on_new_intent(self, intent):
         data = str(intent.getDataString())
         scheme = str(intent.getScheme()).lower()
@@ -481,22 +477,15 @@ class ElectrumWindow(App, Logger, EventListener):
             self.send_screen.do_clear()
 
     def on_qr(self, data: str):
-        from electrum.bitcoin import is_address
+        self.on_data_input(data)
+
+    def on_data_input(self, data: str) -> None:
+        """on_qr / on_paste shared logic"""
         data = data.strip()
-        if is_address(data):
-            self.set_URI(data)
-            return
-        if data.lower().startswith(BITCOIN_BIP21_URI_SCHEME + ':'):
-            self.set_URI(data)
-            return
         if data.lower().startswith('channel_backup:'):
             self.import_channel_backup(data)
             return
-        bolt11_invoice = maybe_extract_bolt11_invoice(data)
-        if bolt11_invoice is not None:
-            self.set_ln_invoice(bolt11_invoice)
-            return
-        # try to decode transaction
+        # try to decode as transaction
         from electrum.transaction import tx_from_any
         try:
             tx = tx_from_any(data)
@@ -505,8 +494,8 @@ class ElectrumWindow(App, Logger, EventListener):
         if tx:
             self.tx_dialog(tx)
             return
-        # show error
-        self.show_error("Unable to decode QR data")
+        # try to decode as URI/address
+        self.set_URI(data)
 
     def update_tab(self, name):
         s = getattr(self, name + '_screen', None)

electrum/gui/kivy/uix/screens.py

@@ -2,6 +2,7 @@ import asyncio
 from decimal import Decimal
 import threading
 from typing import TYPE_CHECKING, List, Optional, Dict, Any
+from urllib.parse import urlparse
 
 from kivy.app import App
 from kivy.clock import Clock
@@ -16,10 +17,12 @@ from electrum.invoices import (PR_DEFAULT_EXPIRATION_WHEN_CREATING,
                                pr_expiration_values, Invoice)
 from electrum import bitcoin, constants
 from electrum.transaction import tx_from_any, PartialTxOutput
-from electrum.util import (parse_URI, InvalidBitcoinURI, TxMinedInfo, maybe_extract_bolt11_invoice,
-                           InvoiceError, format_time, parse_max_spend)
+from electrum.util import (parse_URI, InvalidBitcoinURI, TxMinedInfo, maybe_extract_lightning_payment_identifier,
+                           InvoiceError, format_time, parse_max_spend, BITCOIN_BIP21_URI_SCHEME)
 from electrum.lnaddr import lndecode, LnInvoiceException
+from electrum.lnurl import decode_lnurl, request_lnurl, callback_lnurl, LNURLError, LNURL6Data
 from electrum.logging import Logger
+from electrum.network import Network
 
 from .dialogs.confirm_tx_dialog import ConfirmTxDialog
 
@@ -162,22 +165,42 @@ class SendScreen(CScreen, Logger):
     kvname = 'send'
     payment_request = None  # type: Optional[PaymentRequest]
     parsed_URI = None
+    lnurl_data = None  # type: Optional[LNURL6Data]
 
     def __init__(self, **kwargs):
         CScreen.__init__(self, **kwargs)
         Logger.__init__(self)
         self.is_max = False
+        # note: most the fields get declared in send.kv, this way they are kivy Properties
 
     def set_URI(self, text: str):
+        """Takes
+        Lightning identifiers:
+        * lightning-URI (containing bolt11 or lnurl)
+        * bolt11 invoice
+        * lnurl
+        Bitcoin identifiers:
+        * bitcoin-URI
+        * bitcoin address
+        and sets the sending screen.
+
+        TODO maybe rename method...
+        """
         if not self.app.wallet:
             return
-        # interpret as lighting URI
-        bolt11_invoice = maybe_extract_bolt11_invoice(text)
-        if bolt11_invoice:
-            self.set_ln_invoice(bolt11_invoice)
-        # interpret as BIP21 URI
-        else:
+        text = text.strip()
+        if not text:
+            return
+        if invoice_or_lnurl := maybe_extract_lightning_payment_identifier(text):
+            if invoice_or_lnurl.startswith('lnurl'):
+                self.set_lnurl6(invoice_or_lnurl)
+            else:
+                self.set_bolt11(invoice_or_lnurl)
+        elif text.lower().startswith(BITCOIN_BIP21_URI_SCHEME + ':') or bitcoin.is_address(text):
             self.set_bip21(text)
+        else:
+            self.app.show_error(f"Failed to parse text: {text[:10]}...")
+            return
 
     def set_bip21(self, text: str):
         try:
@@ -194,7 +217,7 @@ class SendScreen(CScreen, Logger):
         self.payment_request = None
         self.is_lightning = False
 
-    def set_ln_invoice(self, invoice: str):
+    def set_bolt11(self, invoice: str):
         try:
             invoice = str(invoice).lower()
             lnaddr = lndecode(invoice)
@@ -207,6 +230,20 @@ class SendScreen(CScreen, Logger):
         self.payment_request = None
         self.is_lightning = True
 
+    def set_lnurl6(self, lnurl: str):
+        url = decode_lnurl(lnurl)
+        domain = urlparse(url).netloc
+        # FIXME network request blocking GUI thread:
+        lnurl_data = Network.run_from_another_thread(request_lnurl(url))
+        if not lnurl_data:
+            return
+        self.lnurl_data = lnurl_data
+        self.address = "invoice from lnurl"
+        self.message = f"lnurl: {domain}: {lnurl_data.metadata_plaintext}"
+        self.amount = self.app.format_amount_and_units(lnurl_data.min_sendable_sat)
+        self.is_lightning = True
+        self.is_lnurl = True  # `bool(self.lnurl_data)` should be equivalent, this is only here as it is a kivy Property
+
     def update(self):
         if self.app.wallet is None:
             return
@@ -263,6 +300,8 @@ class SendScreen(CScreen, Logger):
         self.is_bip70 = False
         self.parsed_URI = None
         self.is_max = False
+        self.lnurl_data = None
+        self.is_lnurl = False
 
     def set_request(self, pr: 'PaymentRequest'):
         self.address = pr.get_requestor()
@@ -277,21 +316,7 @@ class SendScreen(CScreen, Logger):
         if not data:
             self.app.show_info(_("Clipboard is empty"))
             return
-        # try to decode as transaction
-        try:
-            tx = tx_from_any(data)
-            tx.deserialize()
-        except:
-            tx = None
-        if tx:
-            self.app.tx_dialog(tx)
-            return
-        # try to decode as URI/address
-        bolt11_invoice = maybe_extract_bolt11_invoice(data)
-        if bolt11_invoice is not None:
-            self.set_ln_invoice(bolt11_invoice)
-        else:
-            self.set_URI(data)
+        self.app.on_data_input(data)
 
     def read_invoice(self):
         address = str(self.address)
@@ -340,7 +365,35 @@ class SendScreen(CScreen, Logger):
         self.do_clear()
         self.update()
 
+    def _lnurl_get_invoice(self) -> None:
+        assert self.lnurl_data
+        try:
+            amount = self.app.get_amount(self.amount)
+        except:
+            self.app.show_error(_('Invalid amount') + ':\n' + self.amount)
+            return
+        if not (self.lnurl_data.min_sendable_sat <= amount <= self.lnurl_data.max_sendable_sat):
+            self.app.show_error(f'Amount must be between {self.lnurl_data.min_sendable_sat} and {self.lnurl_data.max_sendable_sat} sat.')
+            return
+        try:
+            # FIXME network request blocking GUI thread:
+            invoice_data = Network.run_from_another_thread(callback_lnurl(
+                self.lnurl_data.callback_url,
+                params={'amount': amount * 1000},
+            ))
+        except LNURLError as e:
+            self.app.show_error(f"LNURL request encountered error: {e}")
+            self.do_clear()
+            return
+        invoice = invoice_data.get('pr')
+        self.set_bolt11(invoice)
+        self.lnurl_data = None
+        self.is_lnurl = False
+
     def do_pay(self):
+        if self.lnurl_data:
+            self._lnurl_get_invoice()
+            return
         invoice = self.read_invoice()
         if not invoice:
             return

electrum/gui/kivy/uix/ui_screens/send.kv

@@ -69,6 +69,7 @@
     message: ''
     is_bip70: False
     is_lightning: False
+    is_lnurl: False
     is_locked: self.is_lightning or self.is_bip70
     BoxLayout
         padding: '12dp', '12dp', '12dp', '12dp'
@@ -109,7 +110,7 @@
                     id: amount_e
                     default_text: _('Amount')
                     text: s.amount if s.amount else _('Amount')
-                    disabled: root.is_bip70 or (root.is_lightning and s.amount)
+                    disabled: root.is_bip70 or (root.is_lightning and s.amount and not root.is_lnurl)
                     on_release: Clock.schedule_once(lambda dt: app.amount_dialog(s, not root.is_lightning))
             CardSeparator:
                 color: blue_bottom.foreground_color
@@ -135,6 +136,7 @@
                 size_hint: 0.5, 1
                 on_release: s.do_save()
                 icon: f'atlas://{KIVY_GUI_PATH}/theming/atlas/light/save'
+                disabled: root.is_lnurl
             IconButton:
                 size_hint: 0.5, 1
                 on_release: s.do_clear()
@@ -149,7 +151,7 @@
                 size_hint: 1, 1
                 on_release: Clock.schedule_once(lambda dt: app.scan_qr(on_complete=app.on_qr))
             Button:
-                text: _('Pay')
+                text: _('Pay') if not root.is_lnurl else _('Get Invoice')
                 size_hint: 1, 1
                 on_release: s.do_pay()
         Widget:

electrum/gui/qt/__init__.py

@@ -87,7 +87,7 @@ class OpenFileEventFilter(QObject):
     def eventFilter(self, obj, event):
         if event.type() == QtCore.QEvent.FileOpen:
             if len(self.windows) >= 1:
-                self.windows[0].pay_to_URI(event.url().toString())
+                self.windows[0].handle_payment_identifier(event.url().toString())
                 return True
         return False
 
@@ -383,7 +383,7 @@ class ElectrumGui(BaseElectrumGui, Logger):
                 self.start_new_window(path, uri=None, force_wizard=True)
             return
         if uri:
-            window.pay_to_URI(uri)
+            window.handle_payment_identifier(uri)
         window.bring_to_top()
         window.setWindowState(window.windowState() & ~QtCore.Qt.WindowMinimized | QtCore.Qt.WindowActive)
 

electrum/gui/qt/completion_text_edit.py

@@ -81,6 +81,8 @@ class CompletionTextEdit(ButtonsTextEdit):
             return
 
         QPlainTextEdit.keyPressEvent(self, e)
+        if self.isReadOnly():  # if field became read-only *after* keyPress, exit now
+            return
 
         ctrlOrShift = bool(e.modifiers() & (Qt.ControlModifier | Qt.ShiftModifier))
         if self.completer is None or (ctrlOrShift and not e.text()):

electrum/gui/qt/main_window.py

@@ -38,6 +38,7 @@ import queue
 import asyncio
 from typing import Optional, TYPE_CHECKING, Sequence, List, Union, Dict, Set
 import concurrent.futures
+from urllib.parse import urlparse
 
 from PyQt5.QtGui import QPixmap, QKeySequence, QIcon, QCursor, QFont
 from PyQt5.QtCore import Qt, QRect, QStringListModel, QSize, pyqtSignal, QPoint
@@ -57,12 +58,12 @@ from electrum import (keystore, ecc, constants, util, bitcoin, commands,
 from electrum.bitcoin import COIN, is_address
 from electrum.plugin import run_hook, BasePlugin
 from electrum.i18n import _
-from electrum.util import (format_time,
+from electrum.util import (format_time, get_asyncio_loop,
                            UserCancelled, profiler,
                            bh2u, bfh, InvalidPassword,
                            UserFacingException,
                            get_new_wallet_name, send_exception_to_crash_reporter,
-                           InvalidBitcoinURI, maybe_extract_bolt11_invoice, NotEnoughFunds,
+                           InvalidBitcoinURI, maybe_extract_lightning_payment_identifier, NotEnoughFunds,
                            NoDynamicFeeEstimates,
                            AddTransactionException, BITCOIN_BIP21_URI_SCHEME,
                            InvoiceError, parse_max_spend)
@@ -81,6 +82,7 @@ from electrum.simple_config import SimpleConfig
 from electrum.logging import Logger
 from electrum.lnutil import ln_dummy_address, extract_nodeid, ConnStringFormatError
 from electrum.lnaddr import lndecode, LnInvoiceException
+from electrum.lnurl import decode_lnurl, request_lnurl, callback_lnurl, LNURLError, LNURL6Data
 
 from .exception_window import Exception_Hook
 from .amountedit import AmountEdit, BTCAmountEdit, FreezableLineEdit, FeerateEdit, SizedFreezableLineEdit
@@ -199,12 +201,16 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger, QtEventListener):
 
     payment_request_ok_signal = pyqtSignal()
     payment_request_error_signal = pyqtSignal()
+    lnurl6_round1_signal = pyqtSignal(object, object)
+    lnurl6_round2_signal = pyqtSignal(object)
+    clear_send_tab_signal = pyqtSignal()
     #ln_payment_attempt_signal = pyqtSignal(str)
     computing_privkeys_signal = pyqtSignal()
     show_privkeys_signal = pyqtSignal()
     show_error_signal = pyqtSignal(str)
 
     payment_request: Optional[paymentrequest.PaymentRequest]
+    _lnurl_data: Optional[LNURL6Data] = None
 
     def __init__(self, gui_object: 'ElectrumGui', wallet: Abstract_Wallet):
         QMainWindow.__init__(self)
@@ -309,6 +315,10 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger, QtEventListener):
 
         self.payment_request_ok_signal.connect(self.payment_request_ok)
         self.payment_request_error_signal.connect(self.payment_request_error)
+        self.lnurl6_round1_signal.connect(self.on_lnurl6_round1)
+        self.lnurl6_round2_signal.connect(self.on_lnurl6_round2)
+        self.clear_send_tab_signal.connect(self.do_clear)
+
         self.show_error_signal.connect(self.show_error)
         self.history_list.setFocus(True)
 
@@ -820,7 +830,7 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger, QtEventListener):
         d = self.network.get_donation_address()
         if d:
             host = self.network.get_parameters().server.host
-            self.pay_to_URI('bitcoin:%s?message=donation for %s'%(d, host))
+            self.handle_payment_identifier('bitcoin:%s?message=donation for %s' % (d, host))
         else:
             self.show_error(_('No donation address for this server'))
 
@@ -912,8 +922,8 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger, QtEventListener):
             # this updates "synchronizing" progress
             self.update_status()
         # resolve aliases
-        # FIXME this is a blocking network call that has a timeout of 5 sec
-        self.payto_e.resolve()
+        # FIXME this might do blocking network calls that has a timeout of several seconds
+        self.payto_e.on_timer_check_text()
         self.notify_transactions()
 
     def format_amount(self, amount_sat, is_diff=False, whitespaces=False) -> str:
@@ -1524,7 +1534,6 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger, QtEventListener):
         from .paytoedit import PayToEdit
         self.amount_e = BTCAmountEdit(self.get_decimal_point)
         self.payto_e = PayToEdit(self)
-        self.payto_e.addPasteButton()
         msg = (_("Recipient of the funds.") + "\n\n"
                + _("You may enter a Bitcoin address, a label from your list of contacts "
                    "(a list of completions will be proposed), "
@@ -1573,7 +1582,7 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger, QtEventListener):
         grid.addWidget(self.max_button, 3, 3)
 
         self.save_button = EnterButton(_("Save"), self.do_save_invoice)
-        self.send_button = EnterButton(_("Pay") + "...", self.do_pay)
+        self.send_button = EnterButton(_("Pay") + "...", self.do_pay_or_get_invoice)
         self.clear_button = EnterButton(_("Clear"), self.do_clear)
 
         buttons = QHBoxLayout()
@@ -1910,7 +1919,43 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger, QtEventListener):
         self.invoice_list.update()
         self.pending_invoice = None
 
-    def do_pay(self):
+    def _lnurl_get_invoice(self) -> None:
+        assert self._lnurl_data
+        amount = self.amount_e.get_amount()
+        if not (self._lnurl_data.min_sendable_sat <= amount <= self._lnurl_data.max_sendable_sat):
+            self.show_error(f'Amount must be between {self._lnurl_data.min_sendable_sat} and {self._lnurl_data.max_sendable_sat} sat.')
+            return
+
+        async def f():
+            try:
+                invoice_data = await callback_lnurl(
+                    self._lnurl_data.callback_url,
+                    params={'amount': self.amount_e.get_amount() * 1000},
+                )
+            except LNURLError as e:
+                self.show_error_signal.emit(f"LNURL request encountered error: {e}")
+                self.clear_send_tab_signal.emit()
+                return
+            invoice = invoice_data.get('pr')
+            self.lnurl6_round2_signal.emit(invoice)
+
+        asyncio.run_coroutine_threadsafe(f(), get_asyncio_loop())  # TODO should be cancellable
+        self.prepare_for_send_tab_network_lookup()
+
+    def on_lnurl6_round2(self, bolt11_invoice: str):
+        self.set_bolt11(bolt11_invoice)
+        self.payto_e.setFrozen(True)
+        self.amount_e.setEnabled(False)
+        self.fiat_send_e.setEnabled(False)
+        for btn in [self.send_button, self.clear_button, self.save_button]:
+            btn.setEnabled(True)
+        self.send_button.restore_original_text()
+        self._lnurl_data = None
+
+    def do_pay_or_get_invoice(self):
+        if self._lnurl_data:
+            self._lnurl_get_invoice()
+            return
         self.pending_invoice = self.read_invoice()
         if not self.pending_invoice:
             return
@@ -2171,14 +2216,15 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger, QtEventListener):
         self.amount_e.setFrozen(b)
         self.max_button.setEnabled(not b)
 
-    def prepare_for_payment_request(self):
+    def prepare_for_send_tab_network_lookup(self):
         self.show_send_tab()
-        self.payto_e.is_pr = True
+        self.payto_e.disable_checks = True
         for e in [self.payto_e, self.message_e]:
             e.setFrozen(True)
         self.lock_amount(True)
-        self.payto_e.setText(_("please wait..."))
-        return True
+        for btn in [self.save_button, self.send_button, self.clear_button]:
+            btn.setEnabled(False)
+        self.payto_e.setTextNoCheck(_("please wait..."))
 
     def delete_invoices(self, keys):
         for key in keys:
@@ -2195,14 +2241,18 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger, QtEventListener):
             self.do_clear()
             self.payment_request = None
             return
-        self.payto_e.is_pr = True
+        self.payto_e.disable_checks = True
         if not pr.has_expired():
             self.payto_e.setGreen()
         else:
             self.payto_e.setExpired()
-        self.payto_e.setText(pr.get_requestor())
+        self.payto_e.setTextNoCheck(pr.get_requestor())
         self.amount_e.setAmount(pr.get_amount())
         self.message_e.setText(pr.get_memo())
+        self.set_onchain(True)
+        self.max_button.setEnabled(False)
+        for btn in [self.send_button, self.clear_button]:
+            btn.setEnabled(True)
         # signal to set fee
         self.amount_e.textEdited.emit("")
 
@@ -2215,14 +2265,46 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger, QtEventListener):
         self.do_clear()
 
     def on_pr(self, request: 'paymentrequest.PaymentRequest'):
-        self.set_onchain(True)
         self.payment_request = request
         if self.payment_request.verify(self.contacts):
             self.payment_request_ok_signal.emit()
         else:
             self.payment_request_error_signal.emit()
 
-    def set_ln_invoice(self, invoice: str):
+    def set_lnurl6(self, lnurl: str, *, can_use_network: bool = True):
+        try:
+            url = decode_lnurl(lnurl)
+        except LnInvoiceException as e:
+            self.show_error(_("Error parsing Lightning invoice") + f":\n{e}")
+            return
+        if not can_use_network:
+            return
+
+        async def f():
+            try:
+                lnurl_data = await request_lnurl(url)
+            except LNURLError as e:
+                self.show_error_signal.emit(f"LNURL request encountered error: {e}")
+                self.clear_send_tab_signal.emit()
+                return
+            self.lnurl6_round1_signal.emit(lnurl_data, url)
+
+        asyncio.run_coroutine_threadsafe(f(), get_asyncio_loop())  # TODO should be cancellable
+        self.prepare_for_send_tab_network_lookup()
+
+    def on_lnurl6_round1(self, lnurl_data: LNURL6Data, url: str):
+        self._lnurl_data = lnurl_data
+        domain = urlparse(url).netloc
+        self.payto_e.setTextNoCheck(f"invoice from lnurl")
+        self.message_e.setText(f"lnurl: {domain}: {lnurl_data.metadata_plaintext}")
+        self.amount_e.setAmount(lnurl_data.min_sendable_sat)
+        self.amount_e.setFrozen(False)
+        self.send_button.setText(_('Get Invoice'))
+        for btn in [self.send_button, self.clear_button]:
+            btn.setEnabled(True)
+        self.set_onchain(False)
+
+    def set_bolt11(self, invoice: str):
         """Parse ln invoice, and prepare the send tab for it."""
         try:
             lnaddr = lndecode(invoice)
@@ -2238,9 +2320,10 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger, QtEventListener):
         else:
              description = ''
         self.payto_e.setFrozen(True)
-        self.payto_e.setText(pubkey)
+        self.payto_e.setTextNoCheck(pubkey)
         self.payto_e.lightning_invoice = invoice
-        self.message_e.setText(description)
+        if not self.message_e.text():
+            self.message_e.setText(description)
         if lnaddr.get_amount_sat() is not None:
             self.amount_e.setAmount(lnaddr.get_amount_sat())
         self.set_onchain(False)
@@ -2249,9 +2332,10 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger, QtEventListener):
         self._is_onchain = b
         self.max_button.setEnabled(b)
 
-    def set_bip21(self, text: str):
+    def set_bip21(self, text: str, *, can_use_network: bool = True):
+        on_bip70_pr = self.on_pr if can_use_network else None
         try:
-            out = util.parse_URI(text, self.on_pr)
+            out = util.parse_URI(text, on_bip70_pr)
         except InvalidBitcoinURI as e:
             self.show_error(_("Error parsing URI") + f":\n{e}")
             return
@@ -2259,8 +2343,8 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger, QtEventListener):
         r = out.get('r')
         sig = out.get('sig')
         name = out.get('name')
-        if r or (name and sig):
-            self.prepare_for_payment_request()
+        if (r or (name and sig)) and can_use_network:
+            self.prepare_for_send_tab_network_lookup()
             return
         address = out.get('address')
         amount = out.get('amount')
@@ -2268,7 +2352,7 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger, QtEventListener):
         message = out.get('message')
         lightning = out.get('lightning')
         if lightning:
-            self.set_ln_invoice(lightning)
+            self.handle_payment_identifier(lightning, can_use_network=can_use_network)
             return
         # use label as description (not BIP21 compliant)
         if label and not message:
@@ -2280,28 +2364,45 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger, QtEventListener):
         if amount:
             self.amount_e.setAmount(amount)
 
-    def pay_to_URI(self, text: str):
+    def handle_payment_identifier(self, text: str, *, can_use_network: bool = True):
+        """Takes
+        Lightning identifiers:
+        * lightning-URI (containing bolt11 or lnurl)
+        * bolt11 invoice
+        * lnurl
+        Bitcoin identifiers:
+        * bitcoin-URI
+        and sets the sending screen.
+        """
+        text = text.strip()
         if not text:
             return
-        # first interpret as lightning invoice
-        bolt11_invoice = maybe_extract_bolt11_invoice(text)
-        if bolt11_invoice:
-            self.set_ln_invoice(bolt11_invoice)
+        if invoice_or_lnurl := maybe_extract_lightning_payment_identifier(text):
+            if invoice_or_lnurl.startswith('lnurl'):
+                self.set_lnurl6(invoice_or_lnurl, can_use_network=can_use_network)
+            else:
+                self.set_bolt11(invoice_or_lnurl)
+        elif text.lower().startswith(util.BITCOIN_BIP21_URI_SCHEME + ':'):
+            self.set_bip21(text, can_use_network=can_use_network)
         else:
-            self.set_bip21(text)
+            raise ValueError("Could not handle payment identifier.")
         # update fiat amount
         self.amount_e.textEdited.emit("")
         self.show_send_tab()
 
     def do_clear(self):
+        self._lnurl_data = None
+        self.send_button.restore_original_text()
         self.max_button.setChecked(False)
         self.payment_request = None
         self.payto_URI = None
-        self.payto_e.is_pr = False
+        self.payto_e.do_clear()
         self.set_onchain(False)
-        for e in [self.payto_e, self.message_e, self.amount_e]:
+        for e in [self.message_e, self.amount_e]:
             e.setText('')
             e.setFrozen(False)
+        for e in [self.send_button, self.save_button, self.clear_button, self.amount_e, self.fiat_send_e]:
+            e.setEnabled(True)
         self.update_status()
         run_hook('do_clear', self)
 
@@ -3121,7 +3222,7 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger, QtEventListener):
                 return
             # if the user scanned a bitcoin URI
             if data.lower().startswith(BITCOIN_BIP21_URI_SCHEME + ':'):
-                self.pay_to_URI(data)
+                self.handle_payment_identifier(data)
                 return
             if data.lower().startswith('channel_backup:'):
                 self.import_channel_backup(data)

electrum/gui/qt/paytoedit.py

@@ -31,11 +31,11 @@ from typing import NamedTuple, Sequence, Optional, List, TYPE_CHECKING
 from PyQt5.QtGui import QFontMetrics, QFont
 
 from electrum import bitcoin
-from electrum.util import bfh, maybe_extract_bolt11_invoice, BITCOIN_BIP21_URI_SCHEME, parse_max_spend
+from electrum.util import bfh, parse_max_spend
 from electrum.transaction import PartialTxOutput
 from electrum.bitcoin import opcodes, construct_script
 from electrum.logging import Logger
-from electrum.lnaddr import LnDecodeException
+from electrum.lnurl import LNURLError
 
 from .qrtextedit import ScanQRTextEdit
 from .completion_text_edit import CompletionTextEdit
@@ -63,9 +63,10 @@ class PayToEdit(CompletionTextEdit, ScanQRTextEdit, Logger):
 
     def __init__(self, win: 'ElectrumWindow'):
         CompletionTextEdit.__init__(self)
-        ScanQRTextEdit.__init__(self, config=win.config)
+        ScanQRTextEdit.__init__(self, config=win.config, setText=self._on_input_btn)
         Logger.__init__(self)
         self.win = win
+        self.app = win.app
         self.amount_edit = win.amount_e
         self.setFont(QFont(MONOSPACE_FONT))
         document = self.document()
@@ -84,10 +85,11 @@ class PayToEdit(CompletionTextEdit, ScanQRTextEdit, Logger):
         self.heightMax = (self.fontSpacing * 10) + self.verticalMargins
 
         self.c = None
-        self.textChanged.connect(self.check_text)
+        self.addPasteButton(setText=self._on_input_btn)
+        self.textChanged.connect(self._on_text_changed)
         self.outputs = []  # type: List[PartialTxOutput]
         self.errors = []  # type: List[PayToLineError]
-        self.is_pr = False
+        self.disable_checks = False
         self.is_alias = False
         self.update_size()
         self.payto_scriptpubkey = None  # type: Optional[bytes]
@@ -99,6 +101,18 @@ class PayToEdit(CompletionTextEdit, ScanQRTextEdit, Logger):
         self.setStyleSheet(frozen_style if b else normal_style)
         self.overlay_widget.setHidden(b)
 
+    def setTextNoCheck(self, text: str):
+        """Sets the text, while also ensuring the new value will not be resolved/checked."""
+        self.previous_payto = text
+        self.setText(text)
+
+    def do_clear(self):
+        self.disable_checks = False
+        self.is_alias = False
+        self.setText('')
+        self.setFrozen(False)
+        self.setEnabled(True)
+
     def setGreen(self):
         self.setStyleSheet(util.ColorScheme.GREEN.as_stylesheet(True))
 
@@ -157,9 +171,29 @@ class PayToEdit(CompletionTextEdit, ScanQRTextEdit, Logger):
         assert bitcoin.is_address(address)
         return address
 
-    def check_text(self):
+    def _on_input_btn(self, text: str):
+        self.setText(text)
+        self._check_text(full_check=True)
+
+    def _on_text_changed(self):
+        if self.app.clipboard().text() == self.toPlainText():
+            # user likely pasted from clipboard
+            self._check_text(full_check=True)
+        else:
+            self._check_text(full_check=False)
+
+    def on_timer_check_text(self):
+        if self.hasFocus():
+            return
+        self._check_text(full_check=True)
+
+    def _check_text(self, *, full_check: bool):
+        if self.previous_payto == str(self.toPlainText()).strip():
+            return
+        if full_check:
+            self.previous_payto = str(self.toPlainText()).strip()
         self.errors = []
-        if self.is_pr:
+        if self.disable_checks:
             return
         # filter out empty lines
         lines = [i for i in self.lines() if i]
@@ -170,14 +204,14 @@ class PayToEdit(CompletionTextEdit, ScanQRTextEdit, Logger):
 
         if len(lines) == 1:
             data = lines[0]
-            # try bip21 URI
-            if data.lower().startswith(BITCOIN_BIP21_URI_SCHEME + ':'):
-                self.win.pay_to_URI(data)
-                return
-            # try LN invoice
-            bolt11_invoice = maybe_extract_bolt11_invoice(data)
-            if bolt11_invoice is not None:
-                self.win.set_ln_invoice(bolt11_invoice)
+            try:
+                self.win.handle_payment_identifier(data, can_use_network=full_check)
+            except LNURLError as e:
+                self.logger.exception("")
+                self.win.show_error(e)
+            except ValueError:
+                pass
+            else:
                 return
             # try "address, amount" on-chain format
             try:
@@ -195,6 +229,12 @@ class PayToEdit(CompletionTextEdit, ScanQRTextEdit, Logger):
                 self.win.set_onchain(True)
                 self.win.lock_amount(False)
                 return
+            if full_check:  # network requests  # FIXME blocking GUI thread
+                # try openalias
+                oa_data = self._resolve_openalias(data)
+                if oa_data:
+                    self._set_openalias(key=data, data=oa_data)
+                    return
         else:
             # there are multiple lines
             self._parse_as_multiline(lines, raise_errors=False)
@@ -256,7 +296,7 @@ class PayToEdit(CompletionTextEdit, ScanQRTextEdit, Logger):
         return len(self.lines()) > 1
 
     def paytomany(self):
-        self.setText("\n\n\n")
+        self.setTextNoCheck("\n\n\n")
         self.update_size()
 
     def update_size(self):
@@ -276,44 +316,34 @@ class PayToEdit(CompletionTextEdit, ScanQRTextEdit, Logger):
         # The scrollbar visibility can have changed so we update the overlay position here
         self._updateOverlayPos()
 
-    def resolve(self):
-        self.is_alias = False
-        if self.hasFocus():
-            return
-        if self.is_multiline():  # only supports single line entries atm
-            return
-        if self.is_pr:
-            return
-        key = str(self.toPlainText())
+    def _resolve_openalias(self, text: str) -> Optional[dict]:
+        key = text
         key = key.strip()  # strip whitespaces
-        if key == self.previous_payto:
-            return
-        self.previous_payto = key
-        if not (('.' in key) and (not '<' in key) and (not ' ' in key)):
-            return
+        if not (('.' in key) and ('<' not in key) and (' ' not in key)):
+            return None
         parts = key.split(sep=',')  # assuming single line
         if parts and len(parts) > 0 and bitcoin.is_address(parts[0]):
-            return
+            return None
         try:
             data = self.win.contacts.resolve(key)
         except Exception as e:
             self.logger.info(f'error resolving address/alias: {repr(e)}')
-            return
-        if not data:
-            return
-        self.is_alias = True
+            return None
+        return data or None
 
+    def _set_openalias(self, *, key: str, data: dict) -> bool:
+        self.is_alias = True
+        self.setFrozen(True)
+        key = key.strip()  # strip whitespaces
         address = data.get('address')
         name = data.get('name')
         new_url = key + ' <' + address + '>'
-        self.setText(new_url)
-        self.previous_payto = new_url
+        self.setTextNoCheck(new_url)
 
         #if self.win.config.get('openalias_autoadd') == 'checked':
         self.win.contacts[key] = ('openalias', name)
         self.win.contact_list.update()
 
-        self.setFrozen(True)
         if data.get('type') == 'openalias':
             self.validated = data.get('validated')
             if self.validated:
@@ -322,3 +352,4 @@ class PayToEdit(CompletionTextEdit, ScanQRTextEdit, Logger):
                 self.setExpired()
         else:
             self.validated = None
+        return True

electrum/gui/qt/qrtextedit.py

@@ -1,3 +1,5 @@
+from typing import Callable
+
 from electrum.i18n import _
 from electrum.plugin import run_hook
 from electrum.simple_config import SimpleConfig
@@ -21,11 +23,16 @@ class ShowQRTextEdit(ButtonsTextEdit):
 
 class ScanQRTextEdit(ButtonsTextEdit, MessageBoxMixin):
 
-    def __init__(self, text="", allow_multi: bool = False, *, config: SimpleConfig):
+    def __init__(
+            self, text="", allow_multi: bool = False,
+            *,
+            config: SimpleConfig,
+            setText: Callable[[str], None] = None,
+    ):
         ButtonsTextEdit.__init__(self, text)
         self.setReadOnly(False)
-        self.add_file_input_button(config=config, show_error=self.show_error)
-        self.add_qr_input_button(config=config, show_error=self.show_error, allow_multi=allow_multi)
+        self.add_file_input_button(config=config, show_error=self.show_error, setText=setText)
+        self.add_qr_input_button(config=config, show_error=self.show_error, allow_multi=allow_multi, setText=setText)
         run_hook('scan_text_edit', self)
 
     def contextMenuEvent(self, e):

electrum/gui/qt/util.py

@@ -75,11 +75,15 @@ class EnterButton(QPushButton):
         QPushButton.__init__(self, text)
         self.func = func
         self.clicked.connect(func)
+        self._orig_text = text
 
     def keyPressEvent(self, e):
         if e.key() in [Qt.Key_Return, Qt.Key_Enter]:
             self.func()
 
+    def restore_original_text(self):
+        self.setText(self._orig_text)
+
 
 class ThreadedButton(QPushButton):
     def __init__(self, text, task, on_success=None, on_error=None):

electrum/lnurl.py

@@ -0,0 +1,108 @@
+"""Module for lnurl-related functionality."""
+# https://github.com/sipa/bech32/tree/master/ref/python
+# https://github.com/lnbits/lnurl
+
+import asyncio
+import json
+from typing import Callable, Optional, NamedTuple, Any, TYPE_CHECKING
+import re
+
+import aiohttp.client_exceptions
+from aiohttp import ClientResponse
+
+from electrum.segwit_addr import bech32_decode, Encoding, convertbits
+from electrum.lnaddr import LnDecodeException
+from electrum.network import Network
+
+if TYPE_CHECKING:
+    from collections.abc import Coroutine
+
+
+class LNURLError(Exception):
+    pass
+
+
+def decode_lnurl(lnurl: str) -> str:
+    """Converts bech32 encoded lnurl to url."""
+    decoded_bech32 = bech32_decode(
+        lnurl, ignore_long_length=True
+    )
+    hrp = decoded_bech32.hrp
+    data = decoded_bech32.data
+    if decoded_bech32.encoding is None:
+        raise LnDecodeException("Bad bech32 checksum")
+    if decoded_bech32.encoding != Encoding.BECH32:
+        raise LnDecodeException("Bad bech32 encoding: must be using vanilla BECH32")
+    if not hrp.startswith("lnurl"):
+        raise LnDecodeException("Does not start with lnurl")
+    data = convertbits(data, 5, 8, False)
+    url = bytes(data).decode("utf-8")
+    return url
+
+
+class LNURL6Data(NamedTuple):
+    callback_url: str
+    max_sendable_sat: int
+    min_sendable_sat: int
+    metadata_plaintext: str
+    #tag: str = "payRequest"
+
+
+async def _request_lnurl(url: str) -> dict:
+    """Requests payment data from a lnurl."""
+    try:
+        response = await Network.async_send_http_on_proxy("get", url, timeout=10)
+    except asyncio.TimeoutError as e:
+        raise LNURLError("Server did not reply in time.") from e
+    except aiohttp.client_exceptions.ClientError as e:
+        raise LNURLError(f"Client error: {e}") from e
+    # TODO: handling of specific client errors
+    response = json.loads(response)
+    if "metadata" in response:
+        response["metadata"] = json.loads(response["metadata"])
+    status = response.get("status")
+    if status and status == "ERROR":
+        raise LNURLError(f"LNURL request encountered an error: {response['reason']}")
+    return response
+
+
+async def request_lnurl(url: str) -> Optional[LNURL6Data]:
+    lnurl_dict = await _request_lnurl(url)
+    tag = lnurl_dict.get('tag')
+    if tag != 'payRequest':  # only LNURL6 is handled atm
+        return None
+    metadata = lnurl_dict.get('metadata')
+    metadata_plaintext = ""
+    for m in metadata:
+        if m[0] == 'text/plain':
+            metadata_plaintext = str(m[1])
+    data = LNURL6Data(
+        callback_url=lnurl_dict['callback'],
+        max_sendable_sat=int(lnurl_dict['maxSendable']) // 1000,
+        min_sendable_sat=int(lnurl_dict['minSendable']) // 1000,
+        metadata_plaintext=metadata_plaintext,
+    )
+    return data
+
+
+async def callback_lnurl(url: str, params: dict) -> dict:
+    """Requests an invoice from a lnurl supporting server."""
+    try:
+        response = await Network.async_send_http_on_proxy("get", url, params=params)
+    except aiohttp.client_exceptions.ClientError as e:
+        raise LNURLError(f"Client error: {e}") from e
+    # TODO: handling of specific errors
+    response = json.loads(response)
+    status = response.get("status")
+    if status and status == "ERROR":
+        raise LNURLError(f"LNURL request encountered an error: {response['reason']}")
+    return response
+
+
+def lightning_address_to_url(address: str) -> Optional[str]:
+    """Converts an email-type lightning address to a decoded lnurl.
+    see https://github.com/fiatjaf/lnurl-rfc/blob/luds/16.md
+    """
+    if re.match(r"[^@]+@[^@]+\.[^@]+", address):
+        username, domain = address.split("@")
+        return f"https://{domain}/.well-known/lnurlp/{username}"

electrum/network.py

@@ -1297,7 +1297,7 @@ class Network(Logger, NetworkRetryManager[ServerAddr]):
     @classmethod
     async def async_send_http_on_proxy(
             cls, method: str, url: str, *,
-            params: str = None,
+            params: dict = None,
             body: bytes = None,
             json: dict = None,
             headers=None,

electrum/tests/test_lnurl.py

@@ -0,0 +1,12 @@
+from unittest import TestCase
+
+from electrum import lnurl
+
+
+class TestLnurl(TestCase):
+    def test_decode(self):
+        LNURL = (
+            "LNURL1DP68GURN8GHJ7UM9WFMXJCM99E5K7TELWY7NXENRXVMRGDTZXSENJCM98PJNWXQ96S9"
+        )
+        url = lnurl.decode_lnurl(LNURL)
+        self.assertTrue("https://service.io/?q=3fc3645b439ce8e7", url)

electrum/util.py

@@ -1065,7 +1065,7 @@ def create_bip21_uri(addr, amount_sat: Optional[int], message: Optional[str],
     return str(urllib.parse.urlunparse(p))
 
 
-def maybe_extract_bolt11_invoice(data: str) -> Optional[str]:
+def maybe_extract_lightning_payment_identifier(data: str) -> Optional[str]:
     data = data.strip()  # whitespaces
     data = data.lower()
     if data.startswith(LIGHTNING_URI_SCHEME + ':ln'):
@@ -1076,6 +1076,14 @@ def maybe_extract_bolt11_invoice(data: str) -> Optional[str]:
     return None
 
 
+def is_uri(data: str) -> bool:
+    data = data.lower()
+    if (data.startswith(LIGHTNING_URI_SCHEME + ":") or
+            data.startswith(BITCOIN_BIP21_URI_SCHEME + ':')):
+        return True
+    return False
+
+
 # Python bug (http://bugs.python.org/issue1927) causes raw_input
 # to be redirected improperly between stdin/stderr on Unix systems
 #TODO: py3