lightning qr codes: more robust parsing

kivy qr code handling did not accept "lightning:" prefix or uppercase

electrum/gui/kivy/main_window.py

@@ -11,10 +11,10 @@ from typing import TYPE_CHECKING, Optional
 
 from electrum.storage import WalletStorage, StorageReadWriteError
 from electrum.wallet import Wallet, InternalAddressCorruption
-from electrum.util import profiler, InvalidPassword, send_exception_to_crash_reporter
 from electrum.plugin import run_hook
-from electrum.util import format_satoshis, format_satoshis_plain, format_fee_satoshis
-from electrum.util import PR_UNPAID, PR_PAID, PR_EXPIRED, PR_FAILED, PR_INFLIGHT
+from electrum.util import (profiler, InvalidPassword, send_exception_to_crash_reporter,
+                           format_satoshis, format_satoshis_plain, format_fee_satoshis,
+                           PR_PAID, PR_FAILED, maybe_extract_bolt11_invoice)
 from electrum import blockchain
 from electrum.network import Network, TxBroadcastError, BestEffortRequestFailed
 from .i18n import _
@@ -385,7 +385,7 @@ class ElectrumWindow(App):
             self.send_screen.do_clear()
 
     def on_qr(self, data):
-        from electrum.bitcoin import base_decode, is_address
+        from electrum.bitcoin import is_address
         data = data.strip()
         if is_address(data):
             self.set_URI(data)
@@ -393,8 +393,9 @@ class ElectrumWindow(App):
         if data.startswith('bitcoin:'):
             self.set_URI(data)
             return
-        if data.startswith('ln'):
-            self.set_ln_invoice(data)
+        bolt11_invoice = maybe_extract_bolt11_invoice(data)
+        if bolt11_invoice is not None:
+            self.set_ln_invoice(bolt11_invoice)
             return
         # try to decode transaction
         from electrum.transaction import tx_from_any

electrum/gui/kivy/uix/screens.py

@@ -26,8 +26,9 @@ from electrum.util import profiler, parse_URI, format_time, InvalidPassword, Not
 from electrum.util import PR_TYPE_ONCHAIN, PR_TYPE_LN
 from electrum import bitcoin, constants
 from electrum.transaction import Transaction, tx_from_any, PartialTransaction, PartialTxOutput
-from electrum.util import send_exception_to_crash_reporter, parse_URI, InvalidBitcoinURI
-from electrum.util import PR_UNPAID, PR_PAID, PR_UNKNOWN, PR_EXPIRED, PR_INFLIGHT, TxMinedInfo, get_request_status, pr_expiration_values
+from electrum.util import (parse_URI, InvalidBitcoinURI, PR_PAID, PR_UNKNOWN, PR_EXPIRED,
+                           PR_INFLIGHT, TxMinedInfo, get_request_status, pr_expiration_values,
+                           maybe_extract_bolt11_invoice)
 from electrum.plugin import run_hook
 from electrum.wallet import InternalAddressCorruption
 from electrum import simple_config
@@ -204,6 +205,7 @@ class SendScreen(CScreen):
 
     def set_ln_invoice(self, invoice):
         try:
+            invoice = str(invoice).lower()
             lnaddr = lndecode(invoice, expected_hrp=constants.net.SEGWIT_HRP)
         except Exception as e:
             self.app.show_info(invoice + _(" is not a valid Lightning invoice: ") + repr(e)) # repr because str(Exception()) == ''
@@ -282,12 +284,10 @@ class SendScreen(CScreen):
         if tx:
             self.app.tx_dialog(tx)
             return
-        lower = data.lower()
-        if lower.startswith('lightning:ln'):
-            lower = lower[10:]
         # try to decode as URI/address
-        if lower.startswith('ln'):
-            self.set_ln_invoice(lower)
+        bolt11_invoice = maybe_extract_bolt11_invoice(data)
+        if bolt11_invoice is not None:
+            self.set_ln_invoice(bolt11_invoice)
         else:
             self.set_URI(data)
 

electrum/gui/qt/paytoedit.py

@@ -25,12 +25,12 @@
 
 import re
 from decimal import Decimal
-from typing import NamedTuple, Sequence, Optional, List
+from typing import NamedTuple, Sequence, Optional, List, TYPE_CHECKING
 
 from PyQt5.QtGui import QFontMetrics
 
 from electrum import bitcoin
-from electrum.util import bfh
+from electrum.util import bfh, maybe_extract_bolt11_invoice
 from electrum.transaction import push_script, PartialTxOutput
 from electrum.bitcoin import opcodes
 from electrum.logging import Logger
@@ -40,6 +40,10 @@ from .qrtextedit import ScanQRTextEdit
 from .completion_text_edit import CompletionTextEdit
 from . import util
 
+if TYPE_CHECKING:
+    from .main_window import ElectrumWindow
+
+
 RE_ALIAS = r'(.*?)\s*\<([0-9A-Za-z]{1,})\>'
 
 frozen_style = "QWidget {border:none;}"
@@ -54,7 +58,7 @@ class PayToLineError(NamedTuple):
 
 class PayToEdit(CompletionTextEdit, ScanQRTextEdit, Logger):
 
-    def __init__(self, win):
+    def __init__(self, win: 'ElectrumWindow'):
         CompletionTextEdit.__init__(self)
         ScanQRTextEdit.__init__(self)
         Logger.__init__(self)
@@ -140,16 +144,14 @@ class PayToEdit(CompletionTextEdit, ScanQRTextEdit, Logger):
             if data.startswith("bitcoin:"):
                 self.win.pay_to_URI(data)
                 return
-            lower = data.lower()
-            if lower.startswith("lightning:ln"):
-                lower = lower[10:]
-            if lower.startswith("ln"):
+            bolt11_invoice = maybe_extract_bolt11_invoice(data)
+            if bolt11_invoice is not None:
                 try:
-                    self.win.parse_lightning_invoice(lower)
+                    self.win.parse_lightning_invoice(bolt11_invoice)
                 except LnDecodeException as e:
                     self.errors.append(PayToLineError(idx=0, line_content=data, exc=e))
                 else:
-                    self.lightning_invoice = lower
+                    self.lightning_invoice = bolt11_invoice
                 return
             try:
                 self.payto_scriptpubkey = self.parse_output(data)

electrum/util.py

@@ -889,6 +889,15 @@ 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]:
+    lower = data.lower()
+    if lower.startswith('lightning:ln'):
+        lower = lower[10:]
+    if lower.startswith('ln'):
+        return lower
+    return None
+
+
 # Python bug (http://bugs.python.org/issue1927) causes raw_input
 # to be redirected improperly between stdin/stderr on Unix systems
 #TODO: py3