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Add OutboundV2Channel struct
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@dunxen
dunxen committed Feb 15, 2024
1 parent b54396e commit 7fbca89
Showing 1 changed file with 162 additions and 35 deletions.
197 changes: 162 additions & 35 deletions lightning/src/ln/channel.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1848,7 +1848,10 @@ impl<SP: Deref> ChannelContext<SP> where SP::Target: SignerProvider {
current_chain_height: u32,
outbound_scid_alias: u64,
temporary_channel_id: Option<ChannelId>,
channel_type: ChannelTypeFeatures,
holder_selected_channel_reserve_satoshis: u64,
channel_keys_id: [u8; 32],
holder_signer: <SP::Target as SignerProvider>::EcdsaSigner,
pubkeys: ChannelPublicKeys,
) -> Result<ChannelContext<SP>, APIError>
where
ES::Target: EntropySource,
Expand All @@ -1859,9 +1862,6 @@ impl<SP: Deref> ChannelContext<SP> where SP::Target: SignerProvider {
let channel_value_satoshis = funding_satoshis;

let holder_selected_contest_delay = config.channel_handshake_config.our_to_self_delay;
let channel_keys_id = signer_provider.generate_channel_keys_id(false, channel_value_satoshis, user_id);
let holder_signer = signer_provider.derive_channel_signer(channel_value_satoshis, channel_keys_id);
let pubkeys = holder_signer.pubkeys().clone();

if !their_features.supports_wumbo() && channel_value_satoshis > MAX_FUNDING_SATOSHIS_NO_WUMBO {
return Err(APIError::APIMisuseError{err: format!("funding_value must not exceed {}, it was {}", MAX_FUNDING_SATOSHIS_NO_WUMBO, channel_value_satoshis)});
Expand All @@ -1876,13 +1876,8 @@ impl<SP: Deref> ChannelContext<SP> where SP::Target: SignerProvider {
if holder_selected_contest_delay < BREAKDOWN_TIMEOUT {
return Err(APIError::APIMisuseError {err: format!("Configured with an unreasonable our_to_self_delay ({}) putting user funds at risks", holder_selected_contest_delay)});
}
let holder_selected_channel_reserve_satoshis = get_holder_selected_channel_reserve_satoshis(channel_value_satoshis, config);
if holder_selected_channel_reserve_satoshis < MIN_CHAN_DUST_LIMIT_SATOSHIS {
// Protocol level safety check in place, although it should never happen because
// of `MIN_THEIR_CHAN_RESERVE_SATOSHIS`
return Err(APIError::APIMisuseError { err: format!("Holder selected channel reserve below implemention limit dust_limit_satoshis {}", holder_selected_channel_reserve_satoshis) });
}

let channel_type = get_initial_channel_type(&config, their_features);
debug_assert!(channel_type.is_subset(&channelmanager::provided_channel_type_features(&config)));

let (commitment_conf_target, anchor_outputs_value_msat) = if channel_type.supports_anchors_zero_fee_htlc_tx() {
Expand Down Expand Up @@ -1939,6 +1934,7 @@ impl<SP: Deref> ChannelContext<SP> where SP::Target: SignerProvider {
channel_state: ChannelState::NegotiatingFunding(NegotiatingFundingFlags::OUR_INIT_SENT),
announcement_sigs_state: AnnouncementSigsState::NotSent,
secp_ctx,
// We'll add our counterparty's `funding_satoshis` when we receive `accept_channel2`.
channel_value_satoshis,

latest_monitor_update_id: 0,
Expand Down Expand Up @@ -1972,6 +1968,8 @@ impl<SP: Deref> ChannelContext<SP> where SP::Target: SignerProvider {
signer_pending_commitment_update: false,
signer_pending_funding: false,

// We'll add our counterparty's `funding_satoshis` to these max commitment output assertions
// when we receive `accept_channel2`.
#[cfg(debug_assertions)]
holder_max_commitment_tx_output: Mutex::new((channel_value_satoshis * 1000 - push_msat, push_msat)),
#[cfg(debug_assertions)]
Expand All @@ -1992,6 +1990,8 @@ impl<SP: Deref> ChannelContext<SP> where SP::Target: SignerProvider {
counterparty_dust_limit_satoshis: 0,
holder_dust_limit_satoshis: MIN_CHAN_DUST_LIMIT_SATOSHIS,
counterparty_max_htlc_value_in_flight_msat: 0,
// We'll adjust this to include our counterparty's `funding_satoshis` when we
// receive `accept_channel2`.
holder_max_htlc_value_in_flight_msat: get_holder_max_htlc_value_in_flight_msat(channel_value_satoshis, &config.channel_handshake_config),
counterparty_selected_channel_reserve_satoshis: None, // Filled in in accept_channel
holder_selected_channel_reserve_satoshis,
Expand Down Expand Up @@ -3415,6 +3415,7 @@ pub(crate) fn get_legacy_default_holder_selected_channel_reserve_satoshis(channe
///
/// This is used both for outbound and inbound channels and has lower bound
/// of `dust_limit_satoshis`.
#[cfg(dual_funding)]
fn get_v2_channel_reserve_satoshis(channel_value_satoshis: u64, dust_limit_satoshis: u64) -> u64 {
// Fixed at 1% of channel value by spec.
let (q, _) = channel_value_satoshis.overflowing_div(100);
Expand Down Expand Up @@ -7165,7 +7166,17 @@ impl<SP: Deref> OutboundV1Channel<SP> where SP::Target: SignerProvider {
where ES::Target: EntropySource,
F::Target: FeeEstimator
{
let channel_type = Self::get_initial_channel_type(&config, their_features);
let holder_selected_channel_reserve_satoshis = get_holder_selected_channel_reserve_satoshis(channel_value_satoshis, config);
if holder_selected_channel_reserve_satoshis < MIN_CHAN_DUST_LIMIT_SATOSHIS {
// Protocol level safety check in place, although it should never happen because
// of `MIN_THEIR_CHAN_RESERVE_SATOSHIS`
return Err(APIError::APIMisuseError { err: format!("Holder selected channel reserve below \
implemention limit dust_limit_satoshis {}", holder_selected_channel_reserve_satoshis) });
}

let channel_keys_id = signer_provider.generate_channel_keys_id(false, channel_value_satoshis, user_id);
let holder_signer = signer_provider.derive_channel_signer(channel_value_satoshis, channel_keys_id);
let pubkeys = holder_signer.pubkeys().clone();

let chan = Self {
context: ChannelContext::new_for_outbound_channel(
Expand All @@ -7181,7 +7192,10 @@ impl<SP: Deref> OutboundV1Channel<SP> where SP::Target: SignerProvider {
current_chain_height,
outbound_scid_alias,
temporary_channel_id,
channel_type,
holder_selected_channel_reserve_satoshis,
channel_keys_id,
holder_signer,
pubkeys,
)?,
unfunded_context: UnfundedChannelContext { unfunded_channel_age_ticks: 0 }
};
Expand Down Expand Up @@ -7279,29 +7293,6 @@ impl<SP: Deref> OutboundV1Channel<SP> where SP::Target: SignerProvider {
Ok(funding_created)
}

fn get_initial_channel_type(config: &UserConfig, their_features: &InitFeatures) -> ChannelTypeFeatures {
// The default channel type (ie the first one we try) depends on whether the channel is
// public - if it is, we just go with `only_static_remotekey` as it's the only option
// available. If it's private, we first try `scid_privacy` as it provides better privacy
// with no other changes, and fall back to `only_static_remotekey`.
let mut ret = ChannelTypeFeatures::only_static_remote_key();
if !config.channel_handshake_config.announced_channel &&
config.channel_handshake_config.negotiate_scid_privacy &&
their_features.supports_scid_privacy() {
ret.set_scid_privacy_required();
}

// Optionally, if the user would like to negotiate the `anchors_zero_fee_htlc_tx` option, we
// set it now. If they don't understand it, we'll fall back to our default of
// `only_static_remotekey`.
if config.channel_handshake_config.negotiate_anchors_zero_fee_htlc_tx &&
their_features.supports_anchors_zero_fee_htlc_tx() {
ret.set_anchors_zero_fee_htlc_tx_required();
}

ret
}

/// If we receive an error message, it may only be a rejection of the channel type we tried,
/// not of our ability to open any channel at all. Thus, on error, we should first call this
/// and see if we get a new `OpenChannel` message, otherwise the channel is failed.
Expand Down Expand Up @@ -7913,6 +7904,117 @@ impl<SP: Deref> InboundV1Channel<SP> where SP::Target: SignerProvider {
}
}

// A not-yet-funded outbound (from holder) channel using V2 channel establishment.
#[cfg(dual_funding)]
pub(super) struct OutboundV2Channel<SP: Deref> where SP::Target: SignerProvider {
pub context: ChannelContext<SP>,
pub unfunded_context: UnfundedChannelContext,
#[cfg(dual_funding)]
pub dual_funding_context: DualFundingChannelContext,
}

#[cfg(dual_funding)]
impl<SP: Deref> OutboundV2Channel<SP> where SP::Target: SignerProvider {
pub fn new<ES: Deref, F: Deref>(
fee_estimator: &LowerBoundedFeeEstimator<F>, entropy_source: &ES, signer_provider: &SP,
counterparty_node_id: PublicKey, their_features: &InitFeatures, funding_satoshis: u64,
user_id: u128, config: &UserConfig, current_chain_height: u32, outbound_scid_alias: u64,
funding_confirmation_target: ConfirmationTarget,
) -> Result<OutboundV2Channel<SP>, APIError>
where ES::Target: EntropySource,
F::Target: FeeEstimator,
{
let channel_keys_id = signer_provider.generate_channel_keys_id(false, funding_satoshis, user_id);
let holder_signer = signer_provider.derive_channel_signer(funding_satoshis, channel_keys_id);
let pubkeys = holder_signer.pubkeys().clone();

let temporary_channel_id = Some(ChannelId::temporary_v2_from_revocation_basepoint(&pubkeys.revocation_basepoint));

let holder_selected_channel_reserve_satoshis = get_v2_channel_reserve_satoshis(
funding_satoshis, MIN_CHAN_DUST_LIMIT_SATOSHIS);

let funding_feerate_sat_per_1000_weight = fee_estimator.bounded_sat_per_1000_weight(funding_confirmation_target);
let funding_tx_locktime = current_chain_height;

let chan = Self {
context: ChannelContext::new_for_outbound_channel(
fee_estimator,
entropy_source,
signer_provider,
counterparty_node_id,
their_features,
funding_satoshis,
0,
user_id,
config,
current_chain_height,
outbound_scid_alias,
temporary_channel_id,
holder_selected_channel_reserve_satoshis,
channel_keys_id,
holder_signer,
pubkeys,
)?,
unfunded_context: UnfundedChannelContext { unfunded_channel_age_ticks: 0 },
dual_funding_context: DualFundingChannelContext {
our_funding_satoshis: funding_satoshis,
their_funding_satoshis: 0,
funding_tx_locktime,
funding_feerate_sat_per_1000_weight,
}
};
Ok(chan)
}

pub fn get_open_channel_v2(&self, chain_hash: ChainHash) -> msgs::OpenChannelV2 {
if self.context.have_received_message() {
debug_assert!(false, "Cannot generate an open_channel2 after we've moved forward");
}

if self.context.cur_holder_commitment_transaction_number != INITIAL_COMMITMENT_NUMBER {
debug_assert!(false, "Tried to send an open_channel2 for a channel that has already advanced");
}

let first_per_commitment_point = self.context.holder_signer.as_ref()
.get_per_commitment_point(self.context.cur_holder_commitment_transaction_number,
&self.context.secp_ctx);
let second_per_commitment_point = self.context.holder_signer.as_ref()
.get_per_commitment_point(self.context.cur_holder_commitment_transaction_number - 1,
&self.context.secp_ctx);
let keys = self.context.get_holder_pubkeys();

msgs::OpenChannelV2 {
common_fields: msgs::CommonOpenChannelFields {
chain_hash,
temporary_channel_id: self.context.temporary_channel_id.unwrap(),
funding_satoshis: self.context.channel_value_satoshis,
dust_limit_satoshis: self.context.holder_dust_limit_satoshis,
max_htlc_value_in_flight_msat: self.context.holder_max_htlc_value_in_flight_msat,
htlc_minimum_msat: self.context.holder_htlc_minimum_msat,
commitment_feerate_sat_per_1000_weight: self.context.feerate_per_kw,
to_self_delay: self.context.get_holder_selected_contest_delay(),
max_accepted_htlcs: self.context.holder_max_accepted_htlcs,
funding_pubkey: keys.funding_pubkey,
revocation_basepoint: keys.revocation_basepoint.to_public_key(),
payment_basepoint: keys.payment_point,
delayed_payment_basepoint: keys.delayed_payment_basepoint.to_public_key(),
htlc_basepoint: keys.htlc_basepoint.to_public_key(),
first_per_commitment_point,
channel_flags: if self.context.config.announced_channel {1} else {0},
shutdown_scriptpubkey: Some(match &self.context.shutdown_scriptpubkey {
Some(script) => script.clone().into_inner(),
None => Builder::new().into_script(),
}),
channel_type: Some(self.context.channel_type.clone()),
},
funding_feerate_sat_per_1000_weight: self.context.feerate_per_kw,
second_per_commitment_point,
locktime: self.dual_funding_context.funding_tx_locktime,
require_confirmed_inputs: None,
}
}
}

// A not-yet-funded inbound (from counterparty) channel using V2 channel establishment.
#[cfg(dual_funding)]
pub(super) struct InboundV2Channel<SP: Deref> where SP::Target: SignerProvider {
Expand Down Expand Up @@ -8067,6 +8169,31 @@ impl<SP: Deref> InboundV2Channel<SP> where SP::Target: SignerProvider {
}
}

// Unfunded channel utilities

fn get_initial_channel_type(config: &UserConfig, their_features: &InitFeatures) -> ChannelTypeFeatures {
// The default channel type (ie the first one we try) depends on whether the channel is
// public - if it is, we just go with `only_static_remotekey` as it's the only option
// available. If it's private, we first try `scid_privacy` as it provides better privacy
// with no other changes, and fall back to `only_static_remotekey`.
let mut ret = ChannelTypeFeatures::only_static_remote_key();
if !config.channel_handshake_config.announced_channel &&
config.channel_handshake_config.negotiate_scid_privacy &&
their_features.supports_scid_privacy() {
ret.set_scid_privacy_required();
}

// Optionally, if the user would like to negotiate the `anchors_zero_fee_htlc_tx` option, we
// set it now. If they don't understand it, we'll fall back to our default of
// `only_static_remotekey`.
if config.channel_handshake_config.negotiate_anchors_zero_fee_htlc_tx &&
their_features.supports_anchors_zero_fee_htlc_tx() {
ret.set_anchors_zero_fee_htlc_tx_required();
}

ret
}

const SERIALIZATION_VERSION: u8 = 3;
const MIN_SERIALIZATION_VERSION: u8 = 3;

Expand Down

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