Add anchor outputs pair in CommitmentTransaction

The anchor ouputs pair is added if there are pending HTLCs. Or a
a per-party anchor is added if the party has a pending balance.
This commit is contained in:
Devrandom 2021-08-22 11:08:28 +02:00
parent 97c29cfd34
commit 8275698f3a
4 changed files with 160 additions and 14 deletions

View file

@ -36,7 +36,7 @@ use prelude::*;
use core::cmp;
use ln::chan_utils;
use util::transaction_utils::sort_outputs;
use ln::channel::INITIAL_COMMITMENT_NUMBER;
use ln::channel::{INITIAL_COMMITMENT_NUMBER, ANCHOR_OUTPUT_VALUE_SATOSHI};
use core::ops::Deref;
use chain;
@ -569,6 +569,7 @@ pub fn build_htlc_transaction(commitment_txid: &Txid, feerate_per_kw: u32, conte
/// <BIP 143 funding_signature>
/// After 16 blocks of confirmation, an alternative satisfying witness could be:
/// <>
/// (empty vector required to satisfy compliance with MINIMALIF-standard rule)
#[inline]
pub(crate) fn get_anchor_redeemscript(funding_pubkey: &PublicKey) -> Script {
Builder::new().push_slice(&funding_pubkey.serialize()[..])
@ -771,7 +772,7 @@ impl HolderCommitmentTransaction {
funding_outpoint: Some(chain::transaction::OutPoint { txid: Default::default(), index: 0 })
};
let mut htlcs_with_aux: Vec<(_, ())> = Vec::new();
let inner = CommitmentTransaction::new_with_auxiliary_htlc_data(0, 0, 0, keys, 0, &mut htlcs_with_aux, &channel_parameters.as_counterparty_broadcastable());
let inner = CommitmentTransaction::new_with_auxiliary_htlc_data(0, 0, 0, false, dummy_key.clone(), dummy_key.clone(), keys, 0, &mut htlcs_with_aux, &channel_parameters.as_counterparty_broadcastable());
HolderCommitmentTransaction {
inner,
counterparty_sig: dummy_sig,
@ -858,6 +859,8 @@ pub struct CommitmentTransaction {
to_countersignatory_value_sat: u64,
feerate_per_kw: u32,
htlcs: Vec<HTLCOutputInCommitment>,
// A boolean that is serialization backwards-compatible
opt_anchors: Option<()>,
// A cache of the parties' pubkeys required to construct the transaction, see doc for trust()
keys: TxCreationKeys,
// For access to the pre-built transaction, see doc for trust()
@ -871,6 +874,7 @@ impl PartialEq for CommitmentTransaction {
self.to_countersignatory_value_sat == o.to_countersignatory_value_sat &&
self.feerate_per_kw == o.feerate_per_kw &&
self.htlcs == o.htlcs &&
self.opt_anchors == o.opt_anchors &&
self.keys == o.keys;
if eq {
debug_assert_eq!(self.built.transaction, o.built.transaction);
@ -888,6 +892,7 @@ impl_writeable_tlv_based!(CommitmentTransaction, {
(8, keys, required),
(10, built, required),
(12, htlcs, vec_type),
(14, opt_anchors, option),
});
impl CommitmentTransaction {
@ -901,9 +906,9 @@ impl CommitmentTransaction {
/// Only include HTLCs that are above the dust limit for the channel.
///
/// (C-not exported) due to the generic though we likely should expose a version without
pub fn new_with_auxiliary_htlc_data<T>(commitment_number: u64, to_broadcaster_value_sat: u64, to_countersignatory_value_sat: u64, keys: TxCreationKeys, feerate_per_kw: u32, htlcs_with_aux: &mut Vec<(HTLCOutputInCommitment, T)>, channel_parameters: &DirectedChannelTransactionParameters) -> CommitmentTransaction {
pub fn new_with_auxiliary_htlc_data<T>(commitment_number: u64, to_broadcaster_value_sat: u64, to_countersignatory_value_sat: u64, opt_anchors: bool, broadcaster_funding_key: PublicKey, countersignatory_funding_key: PublicKey, keys: TxCreationKeys, feerate_per_kw: u32, htlcs_with_aux: &mut Vec<(HTLCOutputInCommitment, T)>, channel_parameters: &DirectedChannelTransactionParameters) -> CommitmentTransaction {
// Sort outputs and populate output indices while keeping track of the auxiliary data
let (outputs, htlcs) = Self::internal_build_outputs(&keys, to_broadcaster_value_sat, to_countersignatory_value_sat, htlcs_with_aux, channel_parameters).unwrap();
let (outputs, htlcs) = Self::internal_build_outputs(&keys, to_broadcaster_value_sat, to_countersignatory_value_sat, htlcs_with_aux, channel_parameters, opt_anchors, &broadcaster_funding_key, &countersignatory_funding_key).unwrap();
let (obscured_commitment_transaction_number, txins) = Self::internal_build_inputs(commitment_number, channel_parameters);
let transaction = Self::make_transaction(obscured_commitment_transaction_number, txins, outputs);
@ -914,6 +919,7 @@ impl CommitmentTransaction {
to_countersignatory_value_sat,
feerate_per_kw,
htlcs,
opt_anchors: if opt_anchors { Some(()) } else { None },
keys,
built: BuiltCommitmentTransaction {
transaction,
@ -922,11 +928,11 @@ impl CommitmentTransaction {
}
}
fn internal_rebuild_transaction(&self, keys: &TxCreationKeys, channel_parameters: &DirectedChannelTransactionParameters) -> Result<BuiltCommitmentTransaction, ()> {
fn internal_rebuild_transaction(&self, keys: &TxCreationKeys, channel_parameters: &DirectedChannelTransactionParameters, broadcaster_funding_key: &PublicKey, countersignatory_funding_key: &PublicKey) -> Result<BuiltCommitmentTransaction, ()> {
let (obscured_commitment_transaction_number, txins) = Self::internal_build_inputs(self.commitment_number, channel_parameters);
let mut htlcs_with_aux = self.htlcs.iter().map(|h| (h.clone(), ())).collect();
let (outputs, _) = Self::internal_build_outputs(keys, self.to_broadcaster_value_sat, self.to_countersignatory_value_sat, &mut htlcs_with_aux, channel_parameters)?;
let (outputs, _) = Self::internal_build_outputs(keys, self.to_broadcaster_value_sat, self.to_countersignatory_value_sat, &mut htlcs_with_aux, channel_parameters, self.opt_anchors.is_some(), broadcaster_funding_key, countersignatory_funding_key)?;
let transaction = Self::make_transaction(obscured_commitment_transaction_number, txins, outputs);
let txid = transaction.txid();
@ -950,7 +956,7 @@ impl CommitmentTransaction {
// - initial sorting of outputs / HTLCs in the constructor, in which case T is auxiliary data the
// caller needs to have sorted together with the HTLCs so it can keep track of the output index
// - building of a bitcoin transaction during a verify() call, in which case T is just ()
fn internal_build_outputs<T>(keys: &TxCreationKeys, to_broadcaster_value_sat: u64, to_countersignatory_value_sat: u64, htlcs_with_aux: &mut Vec<(HTLCOutputInCommitment, T)>, channel_parameters: &DirectedChannelTransactionParameters) -> Result<(Vec<TxOut>, Vec<HTLCOutputInCommitment>), ()> {
fn internal_build_outputs<T>(keys: &TxCreationKeys, to_broadcaster_value_sat: u64, to_countersignatory_value_sat: u64, htlcs_with_aux: &mut Vec<(HTLCOutputInCommitment, T)>, channel_parameters: &DirectedChannelTransactionParameters, opt_anchors: bool, broadcaster_funding_key: &PublicKey, countersignatory_funding_key: &PublicKey) -> Result<(Vec<TxOut>, Vec<HTLCOutputInCommitment>), ()> {
let countersignatory_pubkeys = channel_parameters.countersignatory_pubkeys();
let contest_delay = channel_parameters.contest_delay();
@ -982,6 +988,30 @@ impl CommitmentTransaction {
));
}
if opt_anchors {
if to_broadcaster_value_sat > 0 || !htlcs_with_aux.is_empty() {
let anchor_script = get_anchor_redeemscript(broadcaster_funding_key);
txouts.push((
TxOut {
script_pubkey: anchor_script.to_v0_p2wsh(),
value: ANCHOR_OUTPUT_VALUE_SATOSHI,
},
None,
));
}
if to_countersignatory_value_sat > 0 || !htlcs_with_aux.is_empty() {
let anchor_script = get_anchor_redeemscript(countersignatory_funding_key);
txouts.push((
TxOut {
script_pubkey: anchor_script.to_v0_p2wsh(),
value: ANCHOR_OUTPUT_VALUE_SATOSHI,
},
None,
));
}
}
let mut htlcs = Vec::with_capacity(htlcs_with_aux.len());
for (htlc, _) in htlcs_with_aux {
let script = chan_utils::get_htlc_redeemscript(&htlc, &keys);
@ -1098,7 +1128,7 @@ impl CommitmentTransaction {
if keys != self.keys {
return Err(());
}
let tx = self.internal_rebuild_transaction(&keys, channel_parameters)?;
let tx = self.internal_rebuild_transaction(&keys, channel_parameters, &broadcaster_keys.funding_pubkey, &countersignatory_keys.funding_pubkey)?;
if self.built.transaction != tx.transaction || self.built.txid != tx.txid {
return Err(());
}
@ -1236,8 +1266,105 @@ fn script_for_p2wpkh(key: &PublicKey) -> Script {
#[cfg(test)]
mod tests {
use super::CounterpartyCommitmentSecrets;
use hex;
use ::{hex, chain};
use prelude::*;
use ln::chan_utils::{CommitmentTransaction, TxCreationKeys, ChannelTransactionParameters, CounterpartyChannelTransactionParameters, HTLCOutputInCommitment};
use bitcoin::secp256k1::{PublicKey, SecretKey, Secp256k1};
use util::test_utils;
use chain::keysinterface::{KeysInterface, BaseSign};
use bitcoin::Network;
use ln::PaymentHash;
#[test]
fn test_anchors() {
let secp_ctx = Secp256k1::new();
let seed = [42; 32];
let network = Network::Testnet;
let keys_provider = test_utils::TestKeysInterface::new(&seed, network);
let signer = keys_provider.get_channel_signer(false, 3000);
let counterparty_signer = keys_provider.get_channel_signer(false, 3000);
let delayed_payment_base = &signer.pubkeys().delayed_payment_basepoint;
let per_commitment_secret = SecretKey::from_slice(&hex::decode("1f1e1d1c1b1a191817161514131211100f0e0d0c0b0a09080706050403020100").unwrap()[..]).unwrap();
let per_commitment_point = PublicKey::from_secret_key(&secp_ctx, &per_commitment_secret);
let htlc_basepoint = &signer.pubkeys().htlc_basepoint;
let holder_pubkeys = signer.pubkeys();
let counterparty_pubkeys = counterparty_signer.pubkeys();
let keys = TxCreationKeys::derive_new(&secp_ctx, &per_commitment_point, delayed_payment_base, htlc_basepoint, &counterparty_pubkeys.revocation_basepoint, &counterparty_pubkeys.htlc_basepoint).unwrap();
let channel_parameters = ChannelTransactionParameters {
holder_pubkeys: holder_pubkeys.clone(),
holder_selected_contest_delay: 0,
is_outbound_from_holder: false,
counterparty_parameters: Some(CounterpartyChannelTransactionParameters { pubkeys: counterparty_pubkeys.clone(), selected_contest_delay: 0 }),
funding_outpoint: Some(chain::transaction::OutPoint { txid: Default::default(), index: 0 })
};
let mut htlcs_with_aux: Vec<(_, ())> = Vec::new();
// Generate broadcaster and counterparty outputs
let tx = CommitmentTransaction::new_with_auxiliary_htlc_data(
0, 1000, 2000,
false,
holder_pubkeys.funding_pubkey,
counterparty_pubkeys.funding_pubkey,
keys.clone(), 1,
&mut htlcs_with_aux, &channel_parameters.as_holder_broadcastable()
);
assert_eq!(tx.built.transaction.output.len(), 2);
// Generate broadcaster and counterparty outputs as well as two anchors
let tx = CommitmentTransaction::new_with_auxiliary_htlc_data(
0, 1000, 2000,
true,
holder_pubkeys.funding_pubkey,
counterparty_pubkeys.funding_pubkey,
keys.clone(), 1,
&mut htlcs_with_aux, &channel_parameters.as_holder_broadcastable()
);
assert_eq!(tx.built.transaction.output.len(), 4);
// Generate broadcaster output and anchor
let tx = CommitmentTransaction::new_with_auxiliary_htlc_data(
0, 3000, 0,
true,
holder_pubkeys.funding_pubkey,
counterparty_pubkeys.funding_pubkey,
keys.clone(), 1,
&mut htlcs_with_aux, &channel_parameters.as_holder_broadcastable()
);
assert_eq!(tx.built.transaction.output.len(), 2);
// Generate counterparty output and anchor
let tx = CommitmentTransaction::new_with_auxiliary_htlc_data(
0, 0, 3000,
true,
holder_pubkeys.funding_pubkey,
counterparty_pubkeys.funding_pubkey,
keys.clone(), 1,
&mut htlcs_with_aux, &channel_parameters.as_holder_broadcastable()
);
assert_eq!(tx.built.transaction.output.len(), 2);
// Generate broadcaster output, an HTLC output and two anchors
let payment_hash = PaymentHash([42; 32]);
let htlc_info = HTLCOutputInCommitment {
offered: false,
amount_msat: 1000000,
cltv_expiry: 100,
payment_hash,
transaction_output_index: None,
};
let tx = CommitmentTransaction::new_with_auxiliary_htlc_data(
0, 3000, 0,
true,
holder_pubkeys.funding_pubkey,
counterparty_pubkeys.funding_pubkey,
keys.clone(), 1,
&mut vec![(htlc_info, ())], &channel_parameters.as_holder_broadcastable()
);
assert_eq!(tx.built.transaction.output.len(), 4);
}
#[test]
fn test_per_commitment_storage() {

View file

@ -567,7 +567,9 @@ const COMMITMENT_TX_WEIGHT_PER_HTLC: u64 = 172;
#[cfg(test)]
pub const COMMITMENT_TX_WEIGHT_PER_HTLC: u64 = 172;
/// Maximmum `funding_satoshis` value, according to the BOLT #2 specification
pub const ANCHOR_OUTPUT_VALUE_SATOSHI: u64 = 330;
/// Maximum `funding_satoshis` value, according to the BOLT #2 specification
/// it's 2^24.
pub const MAX_FUNDING_SATOSHIS: u64 = 1 << 24;
@ -1206,6 +1208,11 @@ impl<Signer: Sign> Channel<Signer> {
let mut value_to_a = if local { value_to_self } else { value_to_remote };
let mut value_to_b = if local { value_to_remote } else { value_to_self };
let (funding_pubkey_a, funding_pubkey_b) = if local {
(self.get_holder_pubkeys().funding_pubkey, self.get_counterparty_pubkeys().funding_pubkey)
} else {
(self.get_counterparty_pubkeys().funding_pubkey, self.get_holder_pubkeys().funding_pubkey)
};
if value_to_a >= (broadcaster_dust_limit_satoshis as i64) {
log_trace!(logger, " ...including {} output with value {}", if local { "to_local" } else { "to_remote" }, value_to_a);
@ -1227,6 +1234,9 @@ impl<Signer: Sign> Channel<Signer> {
let tx = CommitmentTransaction::new_with_auxiliary_htlc_data(commitment_number,
value_to_a as u64,
value_to_b as u64,
false,
funding_pubkey_a,
funding_pubkey_b,
keys.clone(),
feerate_per_kw,
&mut included_non_dust_htlcs,

View file

@ -1297,22 +1297,24 @@ fn test_fee_spike_violation_fails_htlc() {
// Get the EnforcingSigner for each channel, which will be used to (1) get the keys
// needed to sign the new commitment tx and (2) sign the new commitment tx.
let (local_revocation_basepoint, local_htlc_basepoint, local_secret, next_local_point) = {
let (local_revocation_basepoint, local_htlc_basepoint, local_secret, next_local_point, local_funding) = {
let chan_lock = nodes[0].node.channel_state.lock().unwrap();
let local_chan = chan_lock.by_id.get(&chan.2).unwrap();
let chan_signer = local_chan.get_signer();
let pubkeys = chan_signer.pubkeys();
(pubkeys.revocation_basepoint, pubkeys.htlc_basepoint,
chan_signer.release_commitment_secret(INITIAL_COMMITMENT_NUMBER),
chan_signer.get_per_commitment_point(INITIAL_COMMITMENT_NUMBER - 2, &secp_ctx))
chan_signer.get_per_commitment_point(INITIAL_COMMITMENT_NUMBER - 2, &secp_ctx),
chan_signer.pubkeys().funding_pubkey)
};
let (remote_delayed_payment_basepoint, remote_htlc_basepoint,remote_point) = {
let (remote_delayed_payment_basepoint, remote_htlc_basepoint, remote_point, remote_funding) = {
let chan_lock = nodes[1].node.channel_state.lock().unwrap();
let remote_chan = chan_lock.by_id.get(&chan.2).unwrap();
let chan_signer = remote_chan.get_signer();
let pubkeys = chan_signer.pubkeys();
(pubkeys.delayed_payment_basepoint, pubkeys.htlc_basepoint,
chan_signer.get_per_commitment_point(INITIAL_COMMITMENT_NUMBER - 1, &secp_ctx))
chan_signer.get_per_commitment_point(INITIAL_COMMITMENT_NUMBER - 1, &secp_ctx),
chan_signer.pubkeys().funding_pubkey)
};
// Assemble the set of keys we can use for signatures for our commitment_signed message.
@ -1341,6 +1343,7 @@ fn test_fee_spike_violation_fails_htlc() {
commitment_number,
95000,
local_chan_balance,
false, local_funding, remote_funding,
commit_tx_keys.clone(),
feerate_per_kw,
&mut vec![(accepted_htlc_info, ())],

View file

@ -861,3 +861,9 @@ impl<A: Writeable, B: Writeable, C: Writeable> Writeable for (A, B, C) {
self.2.write(w)
}
}
impl Readable for () {
fn read<R: Read>(_r: &mut R) -> Result<Self, DecodeError> {
Ok(())
}
}