AaronFiore/electrum
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check dust limits

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* on channel opening we verify that the peer's dust limit is above 354
  sat, the limit for unknown segwit versions
* we constrain the allowed scriptpubkey types for channel closing
* we check that the remote's output is above the relay dust limit for
  the collaborative close case
This commit is contained in:
bitromortac
2021-10-22 12:58:04 +02:00
parent f2f8c4533b
commit 947693c90d
4 changed files with 40 additions and 16 deletions
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26
electrum/lnpeer.py
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@@ -534,7 +534,7 @@ class Peer(Logger):
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 @@ class Peer(Logger):
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 @@ class Peer(Logger):
# 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 @@ class Peer(Logger):
# 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