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lnutil: update ctx fee calculation for anchors

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This commit is contained in:
bitromortac
2021-09-13 11:42:55 +02:00
committed by ThomasV
parent 22f5ff0d0e
commit c8bf515953
4 changed files with 21 additions and 7 deletions
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14
electrum/lnutil.py
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@@ -48,6 +48,7 @@ _logger = get_logger(__name__)
HTLC_TIMEOUT_WEIGHT = 663
HTLC_SUCCESS_WEIGHT = 703
COMMITMENT_TX_WEIGHT = 724
COMMITMENT_TX_WEIGHT_ANCHORS = 1124
HTLC_OUTPUT_WEIGHT = 172
LN_MAX_FUNDING_SAT_LEGACY = pow(2, 24) - 1
@@ -158,6 +159,7 @@ class ChannelConfig(StoredObject):
initial_feerate_per_kw: int,
config: 'SimpleConfig',
peer_features: 'LnFeatures',
has_anchors: bool,
) -> None:
# first we validate the configs separately
local_config.validate_params(funding_sat=funding_sat, config=config, peer_features=peer_features)
@@ -183,7 +185,9 @@ class ChannelConfig(StoredObject):
if funder_config.initial_msat < calc_fees_for_commitment_tx(
num_htlcs=0,
feerate=initial_feerate_per_kw,
is_local_initiator=is_local_initiator)[funder]:
is_local_initiator=is_local_initiator,
has_anchors=has_anchors,
)[funder]:
raise Exception(
"the funder's amount for the initial commitment transaction "
"is not sufficient for full fee payment")
@@ -1004,13 +1008,17 @@ def fee_for_htlc_output(*, feerate: int) -> int:
def calc_fees_for_commitment_tx(*, num_htlcs: int, feerate: int,
is_local_initiator: bool, round_to_sat: bool = True) -> Dict['HTLCOwner', int]:
is_local_initiator: bool, round_to_sat: bool = True, has_anchors: bool) -> Dict['HTLCOwner', int]:
# feerate is in sat/kw
# returns fees in msats
# note: BOLT-02 specifies that msat fees need to be rounded down to sat.
# However, the rounding needs to happen for the total fees, so if the return value
# is to be used as part of additional fee calculation then rounding should be done after that.
overall_weight = COMMITMENT_TX_WEIGHT + num_htlcs * HTLC_OUTPUT_WEIGHT
if has_anchors:
commitment_tx_weight = COMMITMENT_TX_WEIGHT_ANCHORS
else:
commitment_tx_weight = COMMITMENT_TX_WEIGHT
overall_weight = commitment_tx_weight + num_htlcs * HTLC_OUTPUT_WEIGHT
fee = feerate * overall_weight
if round_to_sat:
fee = fee // 1000 * 1000