lnurl: make requests async, don't block Qt GUI, rm LUD-16 support

- in lnurl.py, make request methods async
- in Qt GUI, lnurl network requests no longer block the GUI thread
  - but they still do in the kivy GUI
- "lightning address" (LUD-16) support is removed for now as the
  email addresses are indistinguishable from openalias email addresses
  (both protocols should have added and enforced a prefix, or similar,
   to remove this kind of ambiguity -- now we would need to make a
   network request just to identify what kind of ID we were given)

electrum/gui/kivy/uix/screens.py

@@ -20,8 +20,9 @@ from electrum.transaction import tx_from_any, PartialTxOutput
 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, lightning_address_to_url, LNURLError, LNURL6Data
+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
 
@@ -178,7 +179,6 @@ class SendScreen(CScreen, Logger):
         * lightning-URI (containing bolt11 or lnurl)
         * bolt11 invoice
         * lnurl
-        * lightning address
         Bitcoin identifiers:
         * bitcoin-URI
         * bitcoin address
@@ -191,10 +191,7 @@ class SendScreen(CScreen, Logger):
         text = text.strip()
         if not text:
             return
-        invoice_or_lnurl = maybe_extract_lightning_payment_identifier(text)
+        if invoice_or_lnurl := maybe_extract_lightning_payment_identifier(text):
-        if lightning_address_to_url(text):
-            self.set_lnurl6(text)
-        elif invoice_or_lnurl:
             if invoice_or_lnurl.startswith('lnurl'):
                 self.set_lnurl6(invoice_or_lnurl)
             else:
@@ -234,11 +231,10 @@ class SendScreen(CScreen, Logger):
         self.is_lightning = True
 
     def set_lnurl6(self, lnurl: str):
-        url = lightning_address_to_url(lnurl)
+        url = decode_lnurl(lnurl)
-        if not url:
-            url = decode_lnurl(lnurl)
         domain = urlparse(url).netloc
-        lnurl_data = request_lnurl(url, self.app.network.send_http_on_proxy)
+        # 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
@@ -380,11 +376,11 @@ class SendScreen(CScreen, Logger):
             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:
-            invoice_data = callback_lnurl(
+            # FIXME network request blocking GUI thread:
+            invoice_data = Network.run_from_another_thread(callback_lnurl(
                 self.lnurl_data.callback_url,
                 params={'amount': amount * 1000},
-                request_over_proxy=self.app.network.send_http_on_proxy,
+            ))
-            )
         except LNURLError as e:
             self.app.show_error(f"LNURL request encountered error: {e}")
             self.do_clear()

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

@@ -58,7 +58,7 @@ 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,
@@ -82,7 +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, lightning_address_to_url, LNURLError, LNURL6Data
+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
@@ -201,6 +201,9 @@ 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()
@@ -312,6 +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)
 
@@ -1917,22 +1924,30 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger, QtEventListener):
         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
-        try:
+
-            invoice_data = callback_lnurl(
+        async def f():
-                self._lnurl_data.callback_url,
+            try:
-                params={'amount': self.amount_e.get_amount() * 1000},
+                invoice_data = await callback_lnurl(
-                request_over_proxy=self.network.send_http_on_proxy,
+                    self._lnurl_data.callback_url,
-            )
+                    params={'amount': self.amount_e.get_amount() * 1000},
-        except LNURLError as e:
+                )
-            self.show_error(f"LNURL request encountered error: {e}")
+            except LNURLError as e:
-            self.do_clear()
+                self.show_error_signal.emit(f"LNURL request encountered error: {e}")
-            return
+                self.clear_send_tab_signal.emit()
-        invoice = invoice_data.get('pr')
+                return
-        self.set_bolt11(invoice)
+            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.setDisabled(True)
+        self.amount_e.setEnabled(False)
-        self.fiat_send_e.setDisabled(True)
+        self.fiat_send_e.setEnabled(False)
-        self.save_button.setEnabled(True)
+        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
 
@@ -2200,14 +2215,15 @@ 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)
+        for btn in [self.save_button, self.send_button, self.clear_button]:
+            btn.setEnabled(False)
         self.payto_e.setTextNoCheck(_("please wait..."))
-        return True
 
     def delete_invoices(self, keys):
         for key in keys:
@@ -2224,7 +2240,7 @@ 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:
@@ -2232,6 +2248,10 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger, QtEventListener):
         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("")
 
@@ -2244,34 +2264,43 @@ 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_lnurl6_bech32(self, lnurl: str, *, can_use_network: bool = True):
+    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
-        self.set_lnurl6_url(url, can_use_network=can_use_network)
+        if not can_use_network:
-
-    def set_lnurl6_url(self, url: str, *, lnurl_data: LNURL6Data = None, can_use_network: bool = True):
-        domain = urlparse(url).netloc
-        if lnurl_data is None and can_use_network:
-            lnurl_data = request_lnurl(url, self.network.send_http_on_proxy)
-        if not lnurl_data:
             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
-        self.payto_e.setFrozen(True)
+        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.save_button.setDisabled(True)
+        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):
@@ -2314,7 +2343,7 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger, QtEventListener):
         sig = out.get('sig')
         name = out.get('name')
         if (r or (name and sig)) and can_use_network:
-            self.prepare_for_payment_request()
+            self.prepare_for_send_tab_network_lookup()
             return
         address = out.get('address')
         amount = out.get('amount')
@@ -2347,14 +2376,13 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger, QtEventListener):
         text = text.strip()
         if not text:
             return
-        invoice_or_lnurl = maybe_extract_lightning_payment_identifier(text)
+        if invoice_or_lnurl := maybe_extract_lightning_payment_identifier(text):
-        if invoice_or_lnurl:
             if invoice_or_lnurl.startswith('lnurl'):
-                self.set_lnurl6_bech32(invoice_or_lnurl, can_use_network=can_use_network)
+                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)
+            self.set_bip21(text, can_use_network=can_use_network)
         else:
             raise ValueError("Could not handle payment identifier.")
         # update fiat amount
@@ -2372,7 +2400,7 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger, QtEventListener):
         for e in [self.message_e, self.amount_e]:
             e.setText('')
             e.setFrozen(False)
-        for e in [self.send_button, self.save_button, self.amount_e, self.fiat_send_e]:
+        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)

electrum/gui/qt/paytoedit.py

@@ -35,7 +35,7 @@ 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.lnurl import LNURLError, lightning_address_to_url, request_lnurl, LNURL6Data
+from electrum.lnurl import LNURLError
 
 from .qrtextedit import ScanQRTextEdit
 from .completion_text_edit import CompletionTextEdit
@@ -89,7 +89,7 @@ class PayToEdit(CompletionTextEdit, ScanQRTextEdit, Logger):
         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]
@@ -107,7 +107,7 @@ class PayToEdit(CompletionTextEdit, ScanQRTextEdit, Logger):
         self.setText(text)
 
     def do_clear(self):
-        self.is_pr = False
+        self.disable_checks = False
         self.is_alias = False
         self.setText('')
         self.setFrozen(False)
@@ -193,7 +193,7 @@ class PayToEdit(CompletionTextEdit, ScanQRTextEdit, Logger):
         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]
@@ -229,13 +229,7 @@ class PayToEdit(CompletionTextEdit, ScanQRTextEdit, Logger):
                 self.win.set_onchain(True)
                 self.win.lock_amount(False)
                 return
-            if full_check:  # network requests
+            if full_check:  # network requests  # FIXME blocking GUI thread
-                # try lightning address lnurl-16 (note: names can collide with openalias, so order matters)
-                lnurl_data = self._resolve_lightning_address_lnurl16(data)
-                if lnurl_data:
-                    url = lightning_address_to_url(data)
-                    self.win.set_lnurl6_url(url, lnurl_data=lnurl_data)
-                    return
                 # try openalias
                 oa_data = self._resolve_openalias(data)
                 if oa_data:
@@ -339,6 +333,7 @@ class PayToEdit(CompletionTextEdit, ScanQRTextEdit, Logger):
 
     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')
@@ -349,7 +344,6 @@ class PayToEdit(CompletionTextEdit, ScanQRTextEdit, Logger):
         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:
@@ -359,14 +353,3 @@ class PayToEdit(CompletionTextEdit, ScanQRTextEdit, Logger):
         else:
             self.validated = None
         return True
-
-    def _resolve_lightning_address_lnurl16(self, text: str) -> Optional[LNURL6Data]:
-        url = lightning_address_to_url(text)
-        if not url:
-            return None
-        try:
-            lnurl_data = request_lnurl(url, self.win.network.send_http_on_proxy)
-            return lnurl_data
-        except LNURLError as e:
-            self.logger.info(f"failed to resolve {text} as lnurl16 lightning address. got exc: {e!r}")
-            return None

electrum/lnurl.py

@@ -4,7 +4,7 @@
 
 import asyncio
 import json
-from typing import Callable, Optional, NamedTuple, Any
+from typing import Callable, Optional, NamedTuple, Any, TYPE_CHECKING
 import re
 
 import aiohttp.client_exceptions
@@ -12,6 +12,10 @@ 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):
@@ -44,10 +48,10 @@ class LNURL6Data(NamedTuple):
     #tag: str = "payRequest"
 
 
-def _request_lnurl(url: str, request_over_proxy: Callable) -> dict:
+async def _request_lnurl(url: str) -> dict:
     """Requests payment data from a lnurl."""
     try:
-        response = request_over_proxy("get", url, timeout=10)
+        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:
@@ -62,8 +66,8 @@ def _request_lnurl(url: str, request_over_proxy: Callable) -> dict:
     return response
 
 
-def request_lnurl(url: str, request_over_proxy: Callable) -> Optional[LNURL6Data]:
+async def request_lnurl(url: str) -> Optional[LNURL6Data]:
-    lnurl_dict = _request_lnurl(url, request_over_proxy)
+    lnurl_dict = await _request_lnurl(url)
     tag = lnurl_dict.get('tag')
     if tag != 'payRequest':  # only LNURL6 is handled atm
         return None
@@ -81,10 +85,10 @@ def request_lnurl(url: str, request_over_proxy: Callable) -> Optional[LNURL6Data
     return data
 
 
-def callback_lnurl(url: str, params: dict, request_over_proxy: Callable) -> dict:
+async def callback_lnurl(url: str, params: dict) -> dict:
     """Requests an invoice from a lnurl supporting server."""
     try:
-        response = request_over_proxy("get", url, params=params)
+        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

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,