diff --git a/electrum/bitcoin.py b/electrum/bitcoin.py index 64682dd4a49d..8a79dbca9684 100644 --- a/electrum/bitcoin.py +++ b/electrum/bitcoin.py @@ -349,8 +349,12 @@ def relayfee(network: 'Network' = None) -> int: # see https://github.com/bitcoin/bitcoin/blob/a62f0ed64f8bbbdfe6467ac5ce92ef5b5222d1bd/src/policy/policy.cpp#L14 -DUST_LIMIT_DEFAULT_SAT_LEGACY = 546 -DUST_LIMIT_DEFAULT_SAT_SEGWIT = 294 +# and https://github.com/lightningnetwork/lightning-rfc/blob/7e3dce42cbe4fa4592320db6a4e06c26bb99122b/03-transactions.md#dust-limits +DUST_LIMIT_P2PKH = 546 +DUST_LIMIT_P2SH = 540 +DUST_LIMIT_UNKNOWN_SEGWIT = 354 +DUST_LIMIT_P2WSH = 330 +DUST_LIMIT_P2WPKH = 294 def dust_threshold(network: 'Network' = None) -> int: diff --git a/electrum/lnpeer.py b/electrum/lnpeer.py index 8d8309937f24..c42fc7a1ebc6 100644 --- a/electrum/lnpeer.py +++ b/electrum/lnpeer.py @@ -534,7 +534,7 @@ def make_local_config(self, funding_sat: int, push_msat: int, initiator: HTLCOwn static_remotekey = bfh(wallet.get_public_key(addr)) else: static_remotekey = None - dust_limit_sat = bitcoin.DUST_LIMIT_DEFAULT_SAT_LEGACY + dust_limit_sat = bitcoin.DUST_LIMIT_P2PKH reserve_sat = max(funding_sat // 100, dust_limit_sat) # for comparison of defaults, see # https://github.com/ACINQ/eclair/blob/afa378fbb73c265da44856b4ad0f2128a88ae6c6/eclair-core/src/main/resources/reference.conf#L66 @@ -1697,12 +1697,7 @@ async def on_shutdown(self, chan: Channel, payload): raise UpfrontShutdownScriptViolation("remote didn't use upfront shutdown script it commited to in channel opening") else: # BOLT-02 restrict the scriptpubkey to some templates: - # order by decreasing dust limit - if match_script_against_template(their_scriptpubkey, transaction.SCRIPTPUBKEY_TEMPLATE_P2PKH): - pass - elif match_script_against_template(their_scriptpubkey, transaction.SCRIPTPUBKEY_TEMPLATE_P2SH): - pass - elif self.is_shutdown_anysegwit() and match_script_against_template(their_scriptpubkey, transaction.SCRIPTPUBKEY_TEMPLATE_ANYSEGWIT): + if self.is_shutdown_anysegwit() and match_script_against_template(their_scriptpubkey, transaction.SCRIPTPUBKEY_TEMPLATE_ANYSEGWIT): pass elif match_script_against_template(their_scriptpubkey, transaction.SCRIPTPUBKEY_TEMPLATE_WITNESS_V0): pass @@ -1765,9 +1760,9 @@ async def _shutdown(self, chan: Channel, payload, *, is_local: bool): # BOLT2: The sending node MUST set fee less than or equal to the base fee of the final ctx max_fee = chan.get_latest_fee(LOCAL if is_local else REMOTE) our_fee = min(our_fee, max_fee) - drop_remote = False + drop_to_remote = False def send_closing_signed(): - our_sig, closing_tx = chan.make_closing_tx(our_scriptpubkey, their_scriptpubkey, fee_sat=our_fee, drop_remote=drop_remote) + our_sig, closing_tx = chan.make_closing_tx(our_scriptpubkey, their_scriptpubkey, fee_sat=our_fee, drop_remote=drop_to_remote) self.send_message('closing_signed', channel_id=chan.channel_id, fee_satoshis=our_fee, signature=our_sig) def verify_signature(tx, sig): their_pubkey = chan.config[REMOTE].multisig_key.pubkey @@ -1788,13 +1783,22 @@ def verify_signature(tx, sig): # verify their sig: they might have dropped their output our_sig, closing_tx = chan.make_closing_tx(our_scriptpubkey, their_scriptpubkey, fee_sat=their_fee, drop_remote=False) if verify_signature(closing_tx, their_sig): - drop_remote = False + drop_to_remote = False else: our_sig, closing_tx = chan.make_closing_tx(our_scriptpubkey, their_scriptpubkey, fee_sat=their_fee, drop_remote=True) if verify_signature(closing_tx, their_sig): - drop_remote = True + drop_to_remote = True else: + # this can happen if we consider our output too valuable to drop, + # but the remote drops it because it violates their dust limit raise Exception('failed to verify their signature') + # at this point we know how the closing tx looks like + # check that their output is above their scriptpubkey's network dust limit + if not drop_to_remote: + to_remote_idx = closing_tx.get_output_idxs_from_scriptpubkey(their_scriptpubkey.hex()).pop() + to_remote_amount = closing_tx.outputs()[to_remote_idx].value + transaction.check_scriptpubkey_template_and_dust(their_scriptpubkey, to_remote_amount) + # Agree if difference is lower or equal to one (see below) if abs(our_fee - their_fee) < 2: our_fee = their_fee diff --git a/electrum/lnutil.py b/electrum/lnutil.py index 6971de53d9e5..b6ef77cc0c2a 100644 --- a/electrum/lnutil.py +++ b/electrum/lnutil.py @@ -40,6 +40,7 @@ HTLC_OUTPUT_WEIGHT = 172 LN_MAX_FUNDING_SAT = pow(2, 24) - 1 +DUST_LIMIT_MAX = 1000 # dummy address for fee estimation of funding tx def ln_dummy_address(): @@ -103,10 +104,10 @@ def validate_params(self, *, funding_sat: int) -> None: raise Exception(f"{conf_name}. insane initial_msat={self.initial_msat}. (funding_sat={funding_sat})") if self.reserve_sat < self.dust_limit_sat: raise Exception(f"{conf_name}. MUST set channel_reserve_satoshis greater than or equal to dust_limit_satoshis") - # technically this could be using the lower DUST_LIMIT_DEFAULT_SAT_SEGWIT - # but other implementations are checking against this value too; also let's be conservative - if self.dust_limit_sat < bitcoin.DUST_LIMIT_DEFAULT_SAT_LEGACY: + if self.dust_limit_sat < bitcoin.DUST_LIMIT_UNKNOWN_SEGWIT: raise Exception(f"{conf_name}. dust limit too low: {self.dust_limit_sat} sat") + if self.dust_limit_sat > DUST_LIMIT_MAX: + raise Exception(f"{conf_name}. dust limit too high: {self.dust_limit_sat} sat") if self.reserve_sat > funding_sat // 100: raise Exception(f"{conf_name}. reserve too high: {self.reserve_sat}, funding_sat: {funding_sat}") if self.htlc_minimum_msat > 1_000: diff --git a/electrum/transaction.py b/electrum/transaction.py index bd65802404e0..ba78f80a21b3 100644 --- a/electrum/transaction.py +++ b/electrum/transaction.py @@ -459,6 +459,21 @@ def is_instance(cls, item): SCRIPTPUBKEY_TEMPLATE_ANYSEGWIT = [OP_ANYSEGWIT_VERSION, OPPushDataGeneric(lambda x: x in list(range(2, 40 + 1)))] +def check_scriptpubkey_template_and_dust(scriptpubkey, amount: Optional[int]): + if match_script_against_template(scriptpubkey, SCRIPTPUBKEY_TEMPLATE_P2PKH): + dust_limit = bitcoin.DUST_LIMIT_P2PKH + elif match_script_against_template(scriptpubkey, SCRIPTPUBKEY_TEMPLATE_P2SH): + dust_limit = bitcoin.DUST_LIMIT_P2SH + elif match_script_against_template(scriptpubkey, SCRIPTPUBKEY_TEMPLATE_P2WSH): + dust_limit = bitcoin.DUST_LIMIT_P2WSH + elif match_script_against_template(scriptpubkey, SCRIPTPUBKEY_TEMPLATE_P2WPKH): + dust_limit = bitcoin.DUST_LIMIT_P2WPKH + else: + raise Exception(f'scriptpubkey does not conform to any template: {scriptpubkey.hex()}') + if amount < dust_limit: + raise Exception(f'amount ({amount}) is below dust limit for scriptpubkey type ({dust_limit})') + + def match_script_against_template(script, template) -> bool: """Returns whether 'script' matches 'template'.""" if script is None: