Add option for support_large_channels.

max_funding_sats is a config variable and defaults to the old value.

electrum/gui/qml/qechannelopener.py

@@ -141,7 +141,7 @@ class QEChannelOpener(QObject, AuthMixin):
             return False
         return True
 
-    # FIXME "max" button in amount_dialog should enforce LN_MAX_FUNDING_SAT
+    # FIXME "max" button in amount_dialog should enforce LIGHTNING_MAX_FUNDING_SAT
     @pyqtSlot()
     @pyqtSlot(bool)
     def openChannel(self, confirm_backup_conflict=False):

electrum/gui/qt/new_channel_dialog.py

@@ -4,7 +4,7 @@ from PyQt5.QtWidgets import QLabel, QVBoxLayout, QGridLayout, QPushButton, QComb
 
 from electrum.i18n import _
 from electrum.transaction import PartialTxOutput, PartialTransaction
-from electrum.lnutil import LN_MAX_FUNDING_SAT, MIN_FUNDING_SAT
+from electrum.lnutil import MIN_FUNDING_SAT
 from electrum.lnworker import hardcoded_trampoline_nodes
 from electrum import ecc
 from electrum.util import NotEnoughFunds, NoDynamicFeeEstimates
@@ -131,13 +131,13 @@ class NewChannelDialog(WindowModalDialog):
             self.window.show_error(str(e))
             return
         amount = tx.output_value()
-        amount = min(amount, LN_MAX_FUNDING_SAT)
+        amount = min(amount, self.config.LIGHTNING_MAX_FUNDING_SAT)
         self.amount_e.setAmount(amount)
 
     def run(self):
         if not self.exec_():
             return
-        if self.max_button.isChecked() and self.amount_e.get_amount() < LN_MAX_FUNDING_SAT:
+        if self.max_button.isChecked() and self.amount_e.get_amount() < self.config.LIGHTNING_MAX_FUNDING_SAT:
             # if 'max' enabled and amount is strictly less than max allowed,
             # that means we have fewer coins than max allowed, and hence we can
             # spend all coins

electrum/gui/qt/utxo_list.py

@@ -34,7 +34,7 @@ from PyQt5.QtWidgets import QAbstractItemView, QMenu, QLabel, QHBoxLayout
 from electrum.i18n import _
 from electrum.bitcoin import is_address
 from electrum.transaction import PartialTxInput, PartialTxOutput
-from electrum.lnutil import LN_MAX_FUNDING_SAT, MIN_FUNDING_SAT
+from electrum.lnutil import MIN_FUNDING_SAT
 from electrum.util import profiler
 
 from .util import ColorScheme, MONOSPACE_FONT, EnterButton
@@ -243,7 +243,7 @@ class UTXOList(MyTreeView):
         if self.wallet.lnworker is None:
             return False
         value = sum(x.value_sats() for x in coins)
-        return value >= MIN_FUNDING_SAT and value <= LN_MAX_FUNDING_SAT
+        return value >= MIN_FUNDING_SAT and value <= self.config.LIGHTNING_MAX_FUNDING_SAT
 
     def open_channel_with_coins(self, coins):
         # todo : use a single dialog in new flow

electrum/lnpeer.py

@@ -603,6 +603,9 @@ class Peer(Logger):
     def is_shutdown_anysegwit(self):
         return self.features.supports(LnFeatures.OPTION_SHUTDOWN_ANYSEGWIT_OPT)
 
+    def supports_large_channels(self):
+        return self.features.supports(LnFeatures.OPTION_SUPPORT_LARGE_CHANNELS)
+
     def is_channel_type(self):
         return self.features.supports(LnFeatures.OPTION_CHANNEL_TYPE_OPT)
 

electrum/lnutil.py

@@ -49,7 +49,6 @@ HTLC_SUCCESS_WEIGHT = 703
 COMMITMENT_TX_WEIGHT = 724
 HTLC_OUTPUT_WEIGHT = 172
 
-LN_MAX_FUNDING_SAT = pow(2, 24) - 1
 DUST_LIMIT_MAX = 1000
 
 # dummy address for fee estimation of funding tx
@@ -106,9 +105,6 @@ class ChannelConfig(StoredObject):
                 raise Exception(f"{conf_name}. invalid pubkey in channel config")
         if funding_sat < MIN_FUNDING_SAT:
             raise Exception(f"funding_sat too low: {funding_sat} sat < {MIN_FUNDING_SAT}")
-        # MUST set funding_satoshis to less than 2^24 satoshi
-        if funding_sat > LN_MAX_FUNDING_SAT:
-            raise Exception(f"funding_sat too high: {funding_sat} sat > {LN_MAX_FUNDING_SAT}")
         # MUST set push_msat to equal or less than 1000 * funding_satoshis
         if not (0 <= self.initial_msat <= 1000 * funding_sat):
             raise Exception(f"{conf_name}. insane initial_msat={self.initial_msat}. (funding_sat={funding_sat})")

electrum/lnworker.py

@@ -34,7 +34,6 @@ from .invoices import Invoice, PR_UNPAID, PR_EXPIRED, PR_PAID, PR_INFLIGHT, PR_F
 from .invoices import BaseInvoice
 from .util import NetworkRetryManager, JsonRPCClient, NotEnoughFunds
 from .util import EventListener, event_listener
-from .lnutil import LN_MAX_FUNDING_SAT
 from .keystore import BIP32_KeyStore
 from .bitcoin import COIN
 from .bitcoin import opcodes, make_op_return, address_to_scripthash
@@ -222,6 +221,7 @@ LNWALLET_FEATURES = (
     | LnFeatures.OPTION_SHUTDOWN_ANYSEGWIT_OPT
     | LnFeatures.OPTION_CHANNEL_TYPE_OPT
     | LnFeatures.OPTION_SCID_ALIAS_OPT
+    | LnFeatures.OPTION_SUPPORT_LARGE_CHANNEL_OPT
 )
 
 LNGOSSIP_FEATURES = (
@@ -1156,7 +1156,7 @@ class LNWallet(LNWorker):
         assert lightning_needed > 0
         min_funding_sat = lightning_needed + (lightning_needed // 20) + 1000 # safety margin
         min_funding_sat = max(min_funding_sat, 100_000) # at least 1mBTC
-        if min_funding_sat > LN_MAX_FUNDING_SAT:
+        if min_funding_sat > self.config.LIGHTNING_MAX_FUNDING_SAT:
             return
         fee_est = partial(self.config.estimate_fee, allow_fallback_to_static_rates=True)  # to avoid NoDynamicFeeEstimates
         try:
@@ -1165,7 +1165,7 @@ class LNWallet(LNWorker):
         except NotEnoughFunds:
             return
         # if available, suggest twice that amount:
-        if 2 * min_funding_sat <= LN_MAX_FUNDING_SAT:
+        if 2 * min_funding_sat <= self.config.LIGHTNING_MAX_FUNDING_SAT:
             try:
                 self.mktx_for_open_channel(coins=coins, funding_sat=2*min_funding_sat, node_id=bytes(32), fee_est=fee_est)
                 funding_sat = 2 * min_funding_sat
@@ -1175,8 +1175,8 @@ class LNWallet(LNWorker):
 
     def open_channel(self, *, connect_str: str, funding_tx: PartialTransaction,
                      funding_sat: int, push_amt_sat: int, password: str = None) -> Tuple[Channel, PartialTransaction]:
-        if funding_sat > LN_MAX_FUNDING_SAT:
-            raise Exception(_("Requested channel capacity is over protocol allowed maximum."))
+        if funding_sat > self.config.LIGHTNING_MAX_FUNDING_SAT:
+            raise Exception(_("Requested channel capacity is over maximum."))
         coro = self._open_channel_coroutine(
             connect_str=connect_str, funding_tx=funding_tx, funding_sat=funding_sat,
             push_sat=push_amt_sat, password=password)

electrum/simple_config.py

@@ -888,6 +888,7 @@ class SimpleConfig(Logger):
     LIGHTNING_USE_RECOVERABLE_CHANNELS = ConfigVar('use_recoverable_channels', default=True, type_=bool)
     LIGHTNING_ALLOW_INSTANT_SWAPS = ConfigVar('allow_instant_swaps', default=False, type_=bool)
     LIGHTNING_TO_SELF_DELAY_CSV = ConfigVar('lightning_to_self_delay', default=7 * 144, type_=int)
+    LIGHTNING_MAX_FUNDING_SAT = ConfigVar('lightning_max_funding_sat', default=pow(2, 24) - 1, type_=int)
 
     EXPERIMENTAL_LN_FORWARD_PAYMENTS = ConfigVar('lightning_forward_payments', default=False, type_=bool)
     EXPERIMENTAL_LN_FORWARD_TRAMPOLINE_PAYMENTS = ConfigVar('lightning_forward_trampoline_payments', default=False, type_=bool)