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Implement support for creating V2 channels
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@dunxen
dunxen committed Sep 26, 2023
1 parent 1177318 commit 3a73d2a
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285 changes: 158 additions & 127 deletions lightning/src/ln/channel.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1057,6 +1057,143 @@ impl<SP: Deref> ChannelContext<SP> where SP::Target: SignerProvider {
self.channel_transaction_parameters.funding_outpoint
}

fn do_accept_channel_checks(&mut self, default_limits: &ChannelHandshakeLimits,
their_features: &InitFeatures, msg_dust_limit_satoshis: u64, msg_channel_reserve_satoshis: u64,
msg_to_self_delay: u16, msg_max_accepted_htlcs: u16, msg_htlc_minimum_msat: u64,
msg_max_htlc_value_in_flight_msat: u64, msg_minimum_depth: u32, msg_channel_type: &Option<ChannelTypeFeatures>,
msg_shutdown_scriptpubkey: &Option<Script>, msg_funding_pubkey: PublicKey, msg_revocation_basepoint: PublicKey,
msg_payment_point: PublicKey, msg_delayed_payment_basepoint: PublicKey, msg_htlc_basepoint: PublicKey,
msg_first_per_commitment_point: PublicKey,
) -> Result<(), ChannelError> {
let peer_limits = if let Some(ref limits) = self.inbound_handshake_limits_override { limits } else { default_limits };

// Check sanity of message fields:
if !self.is_outbound() {
return Err(ChannelError::Close("Got an accept_channel message from an inbound peer".to_owned()));
}
if self.channel_state != ChannelState::OurInitSent as u32 {
return Err(ChannelError::Close("Got an accept_channel message at a strange time".to_owned()));
}
if msg_dust_limit_satoshis > 21000000 * 100000000 {
return Err(ChannelError::Close(format!("Peer never wants payout outputs? dust_limit_satoshis was {}", msg_dust_limit_satoshis)));
}
if msg_channel_reserve_satoshis > self.channel_value_satoshis {
return Err(ChannelError::Close(format!("Bogus channel_reserve_satoshis ({}). Must not be greater than ({})", msg_channel_reserve_satoshis, self.channel_value_satoshis)));
}
if msg_dust_limit_satoshis > self.holder_selected_channel_reserve_satoshis {
return Err(ChannelError::Close(format!("Dust limit ({}) is bigger than our channel reserve ({})", msg_dust_limit_satoshis, self.holder_selected_channel_reserve_satoshis)));
}
if msg_channel_reserve_satoshis > self.channel_value_satoshis - self.holder_selected_channel_reserve_satoshis {
return Err(ChannelError::Close(format!("Bogus channel_reserve_satoshis ({}). Must not be greater than channel value minus our reserve ({})",
msg_channel_reserve_satoshis, self.channel_value_satoshis - self.holder_selected_channel_reserve_satoshis)));
}
let full_channel_value_msat = (self.channel_value_satoshis - msg_channel_reserve_satoshis) * 1000;
if msg_htlc_minimum_msat >= full_channel_value_msat {
return Err(ChannelError::Close(format!("Minimum htlc value ({}) is full channel value ({})", msg_htlc_minimum_msat, full_channel_value_msat)));
}
let max_delay_acceptable = u16::min(peer_limits.their_to_self_delay, MAX_LOCAL_BREAKDOWN_TIMEOUT);
if msg_to_self_delay > max_delay_acceptable {
return Err(ChannelError::Close(format!("They wanted our payments to be delayed by a needlessly long period. Upper limit: {}. Actual: {}", max_delay_acceptable, msg_to_self_delay)));
}
if msg_max_accepted_htlcs < 1 {
return Err(ChannelError::Close("0 max_accepted_htlcs makes for a useless channel".to_owned()));
}
if msg_max_accepted_htlcs > MAX_HTLCS {
return Err(ChannelError::Close(format!("max_accepted_htlcs was {}. It must not be larger than {}", msg_max_accepted_htlcs, MAX_HTLCS)));
}

// Now check against optional parameters as set by config...
if msg_htlc_minimum_msat > peer_limits.max_htlc_minimum_msat {
return Err(ChannelError::Close(format!("htlc_minimum_msat ({}) is higher than the user specified limit ({})", msg_htlc_minimum_msat, peer_limits.max_htlc_minimum_msat)));
}
if msg_max_htlc_value_in_flight_msat < peer_limits.min_max_htlc_value_in_flight_msat {
return Err(ChannelError::Close(format!("max_htlc_value_in_flight_msat ({}) is less than the user specified limit ({})", msg_max_htlc_value_in_flight_msat, peer_limits.min_max_htlc_value_in_flight_msat)));
}
if msg_channel_reserve_satoshis > peer_limits.max_channel_reserve_satoshis {
return Err(ChannelError::Close(format!("channel_reserve_satoshis ({}) is higher than the user specified limit ({})", msg_channel_reserve_satoshis, peer_limits.max_channel_reserve_satoshis)));
}
if msg_max_accepted_htlcs < peer_limits.min_max_accepted_htlcs {
return Err(ChannelError::Close(format!("max_accepted_htlcs ({}) is less than the user specified limit ({})", msg_max_accepted_htlcs, peer_limits.min_max_accepted_htlcs)));
}
if msg_dust_limit_satoshis < MIN_CHAN_DUST_LIMIT_SATOSHIS {
return Err(ChannelError::Close(format!("dust_limit_satoshis ({}) is less than the implementation limit ({})", msg_dust_limit_satoshis, MIN_CHAN_DUST_LIMIT_SATOSHIS)));
}
if msg_dust_limit_satoshis > MAX_CHAN_DUST_LIMIT_SATOSHIS {
return Err(ChannelError::Close(format!("dust_limit_satoshis ({}) is greater than the implementation limit ({})", msg_dust_limit_satoshis, MAX_CHAN_DUST_LIMIT_SATOSHIS)));
}
if msg_minimum_depth > peer_limits.max_minimum_depth {
return Err(ChannelError::Close(format!("We consider the minimum depth to be unreasonably large. Expected minimum: ({}). Actual: ({})", peer_limits.max_minimum_depth, msg_minimum_depth)));
}

if let Some(ty) = &msg_channel_type {
if *ty != self.channel_type {
return Err(ChannelError::Close("Channel Type in accept_channel didn't match the one sent in open_channel.".to_owned()));
}
} else if their_features.supports_channel_type() {
// Assume they've accepted the channel type as they said they understand it.
} else {
let channel_type = ChannelTypeFeatures::from_init(&their_features);
if channel_type != ChannelTypeFeatures::only_static_remote_key() {
return Err(ChannelError::Close("Only static_remote_key is supported for non-negotiated channel types".to_owned()));
}
self.channel_type = channel_type.clone();
self.channel_transaction_parameters.channel_type_features = channel_type;
}

let counterparty_shutdown_scriptpubkey = if their_features.supports_upfront_shutdown_script() {
match &msg_shutdown_scriptpubkey {
&Some(ref script) => {
// Peer is signaling upfront_shutdown and has opt-out with a 0-length script. We don't enforce anything
if script.len() == 0 {
None
} else {
if !script::is_bolt2_compliant(&script, their_features) {
return Err(ChannelError::Close(format!("Peer is signaling upfront_shutdown but has provided an unacceptable scriptpubkey format: {}", script)));
}
Some(script.clone())
}
},
// Peer is signaling upfront shutdown but don't opt-out with correct mechanism (a.k.a 0-length script). Peer looks buggy, we fail the channel
&None => {
return Err(ChannelError::Close("Peer is signaling upfront_shutdown but we don't get any script. Use 0-length script to opt-out".to_owned()));
}
}
} else { None };

self.counterparty_dust_limit_satoshis = msg_dust_limit_satoshis;
self.counterparty_max_htlc_value_in_flight_msat = cmp::min(msg_max_htlc_value_in_flight_msat, self.channel_value_satoshis * 1000);
self.counterparty_selected_channel_reserve_satoshis = Some(msg_channel_reserve_satoshis);
self.counterparty_htlc_minimum_msat = msg_htlc_minimum_msat;
self.counterparty_max_accepted_htlcs = msg_max_accepted_htlcs;

if peer_limits.trust_own_funding_0conf {
self.minimum_depth = Some(msg_minimum_depth);
} else {
self.minimum_depth = Some(cmp::max(1, msg_minimum_depth));
}

let counterparty_pubkeys = ChannelPublicKeys {
funding_pubkey: msg_funding_pubkey,
revocation_basepoint: msg_revocation_basepoint,
payment_point: msg_payment_point,
delayed_payment_basepoint: msg_delayed_payment_basepoint,
htlc_basepoint: msg_htlc_basepoint
};

self.channel_transaction_parameters.counterparty_parameters = Some(CounterpartyChannelTransactionParameters {
selected_contest_delay: msg_to_self_delay,
pubkeys: counterparty_pubkeys,
});

self.counterparty_cur_commitment_point = Some(msg_first_per_commitment_point);
self.counterparty_shutdown_scriptpubkey = counterparty_shutdown_scriptpubkey;

self.channel_state = ChannelState::OurInitSent as u32 | ChannelState::TheirInitSent as u32;
self.inbound_handshake_limits_override = None; // We're done enforcing limits on our peer's handshake now.

Ok(())
}

/// Returns the block hash in which our funding transaction was confirmed.
pub fn get_funding_tx_confirmed_in(&self) -> Option<BlockHash> {
self.funding_tx_confirmed_in
Expand Down Expand Up @@ -6008,133 +6145,12 @@ impl<SP: Deref> OutboundV1Channel<SP> where SP::Target: SignerProvider {

// Message handlers
pub fn accept_channel(&mut self, msg: &msgs::AcceptChannel, default_limits: &ChannelHandshakeLimits, their_features: &InitFeatures) -> Result<(), ChannelError> {
let peer_limits = if let Some(ref limits) = self.context.inbound_handshake_limits_override { limits } else { default_limits };

// Check sanity of message fields:
if !self.context.is_outbound() {
return Err(ChannelError::Close("Got an accept_channel message from an inbound peer".to_owned()));
}
if self.context.channel_state != ChannelState::OurInitSent as u32 {
return Err(ChannelError::Close("Got an accept_channel message at a strange time".to_owned()));
}
if msg.dust_limit_satoshis > 21000000 * 100000000 {
return Err(ChannelError::Close(format!("Peer never wants payout outputs? dust_limit_satoshis was {}", msg.dust_limit_satoshis)));
}
if msg.channel_reserve_satoshis > self.context.channel_value_satoshis {
return Err(ChannelError::Close(format!("Bogus channel_reserve_satoshis ({}). Must not be greater than ({})", msg.channel_reserve_satoshis, self.context.channel_value_satoshis)));
}
if msg.dust_limit_satoshis > self.context.holder_selected_channel_reserve_satoshis {
return Err(ChannelError::Close(format!("Dust limit ({}) is bigger than our channel reserve ({})", msg.dust_limit_satoshis, self.context.holder_selected_channel_reserve_satoshis)));
}
if msg.channel_reserve_satoshis > self.context.channel_value_satoshis - self.context.holder_selected_channel_reserve_satoshis {
return Err(ChannelError::Close(format!("Bogus channel_reserve_satoshis ({}). Must not be greater than channel value minus our reserve ({})",
msg.channel_reserve_satoshis, self.context.channel_value_satoshis - self.context.holder_selected_channel_reserve_satoshis)));
}
let full_channel_value_msat = (self.context.channel_value_satoshis - msg.channel_reserve_satoshis) * 1000;
if msg.htlc_minimum_msat >= full_channel_value_msat {
return Err(ChannelError::Close(format!("Minimum htlc value ({}) is full channel value ({})", msg.htlc_minimum_msat, full_channel_value_msat)));
}
let max_delay_acceptable = u16::min(peer_limits.their_to_self_delay, MAX_LOCAL_BREAKDOWN_TIMEOUT);
if msg.to_self_delay > max_delay_acceptable {
return Err(ChannelError::Close(format!("They wanted our payments to be delayed by a needlessly long period. Upper limit: {}. Actual: {}", max_delay_acceptable, msg.to_self_delay)));
}
if msg.max_accepted_htlcs < 1 {
return Err(ChannelError::Close("0 max_accepted_htlcs makes for a useless channel".to_owned()));
}
if msg.max_accepted_htlcs > MAX_HTLCS {
return Err(ChannelError::Close(format!("max_accepted_htlcs was {}. It must not be larger than {}", msg.max_accepted_htlcs, MAX_HTLCS)));
}

// Now check against optional parameters as set by config...
if msg.htlc_minimum_msat > peer_limits.max_htlc_minimum_msat {
return Err(ChannelError::Close(format!("htlc_minimum_msat ({}) is higher than the user specified limit ({})", msg.htlc_minimum_msat, peer_limits.max_htlc_minimum_msat)));
}
if msg.max_htlc_value_in_flight_msat < peer_limits.min_max_htlc_value_in_flight_msat {
return Err(ChannelError::Close(format!("max_htlc_value_in_flight_msat ({}) is less than the user specified limit ({})", msg.max_htlc_value_in_flight_msat, peer_limits.min_max_htlc_value_in_flight_msat)));
}
if msg.channel_reserve_satoshis > peer_limits.max_channel_reserve_satoshis {
return Err(ChannelError::Close(format!("channel_reserve_satoshis ({}) is higher than the user specified limit ({})", msg.channel_reserve_satoshis, peer_limits.max_channel_reserve_satoshis)));
}
if msg.max_accepted_htlcs < peer_limits.min_max_accepted_htlcs {
return Err(ChannelError::Close(format!("max_accepted_htlcs ({}) is less than the user specified limit ({})", msg.max_accepted_htlcs, peer_limits.min_max_accepted_htlcs)));
}
if msg.dust_limit_satoshis < MIN_CHAN_DUST_LIMIT_SATOSHIS {
return Err(ChannelError::Close(format!("dust_limit_satoshis ({}) is less than the implementation limit ({})", msg.dust_limit_satoshis, MIN_CHAN_DUST_LIMIT_SATOSHIS)));
}
if msg.dust_limit_satoshis > MAX_CHAN_DUST_LIMIT_SATOSHIS {
return Err(ChannelError::Close(format!("dust_limit_satoshis ({}) is greater than the implementation limit ({})", msg.dust_limit_satoshis, MAX_CHAN_DUST_LIMIT_SATOSHIS)));
}
if msg.minimum_depth > peer_limits.max_minimum_depth {
return Err(ChannelError::Close(format!("We consider the minimum depth to be unreasonably large. Expected minimum: ({}). Actual: ({})", peer_limits.max_minimum_depth, msg.minimum_depth)));
}

if let Some(ty) = &msg.channel_type {
if *ty != self.context.channel_type {
return Err(ChannelError::Close("Channel Type in accept_channel didn't match the one sent in open_channel.".to_owned()));
}
} else if their_features.supports_channel_type() {
// Assume they've accepted the channel type as they said they understand it.
} else {
let channel_type = ChannelTypeFeatures::from_init(&their_features);
if channel_type != ChannelTypeFeatures::only_static_remote_key() {
return Err(ChannelError::Close("Only static_remote_key is supported for non-negotiated channel types".to_owned()));
}
self.context.channel_type = channel_type.clone();
self.context.channel_transaction_parameters.channel_type_features = channel_type;
}

let counterparty_shutdown_scriptpubkey = if their_features.supports_upfront_shutdown_script() {
match &msg.shutdown_scriptpubkey {
&Some(ref script) => {
// Peer is signaling upfront_shutdown and has opt-out with a 0-length script. We don't enforce anything
if script.len() == 0 {
None
} else {
if !script::is_bolt2_compliant(&script, their_features) {
return Err(ChannelError::Close(format!("Peer is signaling upfront_shutdown but has provided an unacceptable scriptpubkey format: {}", script)));
}
Some(script.clone())
}
},
// Peer is signaling upfront shutdown but don't opt-out with correct mechanism (a.k.a 0-length script). Peer looks buggy, we fail the channel
&None => {
return Err(ChannelError::Close("Peer is signaling upfront_shutdown but we don't get any script. Use 0-length script to opt-out".to_owned()));
}
}
} else { None };

self.context.counterparty_dust_limit_satoshis = msg.dust_limit_satoshis;
self.context.counterparty_max_htlc_value_in_flight_msat = cmp::min(msg.max_htlc_value_in_flight_msat, self.context.channel_value_satoshis * 1000);
self.context.counterparty_selected_channel_reserve_satoshis = Some(msg.channel_reserve_satoshis);
self.context.counterparty_htlc_minimum_msat = msg.htlc_minimum_msat;
self.context.counterparty_max_accepted_htlcs = msg.max_accepted_htlcs;

if peer_limits.trust_own_funding_0conf {
self.context.minimum_depth = Some(msg.minimum_depth);
} else {
self.context.minimum_depth = Some(cmp::max(1, msg.minimum_depth));
}

let counterparty_pubkeys = ChannelPublicKeys {
funding_pubkey: msg.funding_pubkey,
revocation_basepoint: msg.revocation_basepoint,
payment_point: msg.payment_point,
delayed_payment_basepoint: msg.delayed_payment_basepoint,
htlc_basepoint: msg.htlc_basepoint
};

self.context.channel_transaction_parameters.counterparty_parameters = Some(CounterpartyChannelTransactionParameters {
selected_contest_delay: msg.to_self_delay,
pubkeys: counterparty_pubkeys,
});

self.context.counterparty_cur_commitment_point = Some(msg.first_per_commitment_point);
self.context.counterparty_shutdown_scriptpubkey = counterparty_shutdown_scriptpubkey;

self.context.channel_state = ChannelState::OurInitSent as u32 | ChannelState::TheirInitSent as u32;
self.context.inbound_handshake_limits_override = None; // We're done enforcing limits on our peer's handshake now.

Ok(())
self.context.do_accept_channel_checks(
default_limits, their_features, msg.dust_limit_satoshis, msg.channel_reserve_satoshis,
msg.to_self_delay, msg.max_accepted_htlcs, msg.htlc_minimum_msat,
msg.max_htlc_value_in_flight_msat, msg.minimum_depth, &msg.channel_type,
&msg.shutdown_scriptpubkey, msg.funding_pubkey, msg.revocation_basepoint, msg.payment_point,
msg.delayed_payment_basepoint, msg.htlc_basepoint, msg.first_per_commitment_point)
}
}

Expand Down Expand Up @@ -6935,6 +6951,21 @@ impl<SP: Deref> OutboundV2Channel<SP> where SP::Target: SignerProvider {
require_confirmed_inputs: None,
}
}

pub fn accept_channel_v2(&mut self, msg: &msgs::AcceptChannelV2, default_limits: &ChannelHandshakeLimits,
their_features: &InitFeatures) -> Result<(), ChannelError> {
self.context.do_accept_channel_checks(
default_limits, their_features, msg.dust_limit_satoshis, get_v2_channel_reserve_satoshis(
msg.funding_satoshis + self.dual_funding_context.our_funding_satoshis, msg.dust_limit_satoshis),
msg.to_self_delay, msg.max_accepted_htlcs, msg.htlc_minimum_msat,
msg.max_htlc_value_in_flight_msat, msg.minimum_depth, &msg.channel_type,
&msg.shutdown_scriptpubkey, msg.funding_pubkey, msg.revocation_basepoint, msg.payment_basepoint,
msg.delayed_payment_basepoint, msg.htlc_basepoint, msg.first_per_commitment_point)?;

// TODO(dual_funding): V2 Establishment Checks

Ok(())
}
}

// A not-yet-funded inbound (from counterparty) channel using V2 channel establishment.
Expand Down
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