use util::ser::{Readable, ReadableArgs, Writeable, Writer, VecWriter};
use util::logger::Logger;
use util::errors::APIError;
-use util::config::{UserConfig, LegacyChannelConfig, ChannelHandshakeConfig, ChannelHandshakeLimits};
+use util::config::{UserConfig, ChannelConfig, LegacyChannelConfig, ChannelHandshakeConfig, ChannelHandshakeLimits};
use util::scid_utils::scid_from_parts;
use io;
/// transaction (not counting the value of the HTLCs themselves).
pub(crate) const MIN_AFFORDABLE_HTLC_COUNT: usize = 4;
+/// When a [`Channel`] has its [`ChannelConfig`] updated, its existing one is stashed for up to this
+/// number of ticks to allow forwarding HTLCs by nodes that have yet to receive the new
+/// ChannelUpdate prompted by the config update. This value was determined as follows:
+///
+/// * The expected interval between ticks (1 minute).
+/// * The average convergence delay of updates across the network, i.e., ~300 seconds on average
+/// for a node to see an update as seen on `<https://arxiv.org/pdf/2205.12737.pdf>`.
+/// * `EXPIRE_PREV_CONFIG_TICKS` = convergence_delay / tick_interval
+pub(crate) const EXPIRE_PREV_CONFIG_TICKS: usize = 5;
+
// TODO: We should refactor this to be an Inbound/OutboundChannel until initial setup handshaking
// has been completed, and then turn into a Channel to get compiler-time enforcement of things like
// calling channel_id() before we're set up or things like get_outbound_funding_signed on an
// Holder designates channel data owned for the benefice of the user client.
// Counterparty designates channel data owned by the another channel participant entity.
pub(super) struct Channel<Signer: Sign> {
- #[cfg(any(test, feature = "_test_utils"))]
- pub(crate) config: LegacyChannelConfig,
- #[cfg(not(any(test, feature = "_test_utils")))]
config: LegacyChannelConfig,
+ // Track the previous `ChannelConfig` so that we can continue forwarding HTLCs that were
+ // constructed using it. The second element in the tuple corresponds to the number of ticks that
+ // have elapsed since the update occurred.
+ prev_config: Option<(ChannelConfig, usize)>,
+
inbound_handshake_limits_override: Option<ChannelHandshakeLimits>,
user_id: u64,
commit_upfront_shutdown_pubkey: config.channel_handshake_config.commit_upfront_shutdown_pubkey,
},
+ prev_config: None,
+
inbound_handshake_limits_override: Some(config.channel_handshake_limits.clone()),
channel_id: keys_provider.get_secure_random_bytes(),
commit_upfront_shutdown_pubkey: config.channel_handshake_config.commit_upfront_shutdown_pubkey,
},
+ prev_config: None,
+
inbound_handshake_limits_override: None,
channel_id: msg.temporary_channel_id,
self.config.options.max_dust_htlc_exposure_msat
}
+ /// Returns the previous [`ChannelConfig`] applied to this channel, if any.
+ pub fn prev_config(&self) -> Option<ChannelConfig> {
+ self.prev_config.map(|prev_config| prev_config.0)
+ }
+
+ /// Tracks the number of ticks elapsed since the previous [`ChannelConfig`] was updated. Once
+ /// [`EXPIRE_PREV_CONFIG_TICKS`] is reached, the previous config is considered expired and will
+ /// no longer be considered when forwarding HTLCs.
+ pub fn maybe_expire_prev_config(&mut self) {
+ if self.prev_config.is_none() {
+ return;
+ }
+ let prev_config = self.prev_config.as_mut().unwrap();
+ prev_config.1 += 1;
+ if prev_config.1 == EXPIRE_PREV_CONFIG_TICKS {
+ self.prev_config = None;
+ }
+ }
+
+ /// Returns the current [`ChannelConfig`] applied to the channel.
+ pub fn config(&self) -> ChannelConfig {
+ self.config.options
+ }
+
+ /// Updates the channel's config. A bool is returned indicating whether the config update
+ /// applied resulted in a new ChannelUpdate message.
+ pub fn update_config(&mut self, config: &ChannelConfig) -> bool {
+ let did_channel_update =
+ self.config.options.forwarding_fee_proportional_millionths != config.forwarding_fee_proportional_millionths ||
+ self.config.options.forwarding_fee_base_msat != config.forwarding_fee_base_msat ||
+ self.config.options.cltv_expiry_delta != config.cltv_expiry_delta;
+ if did_channel_update {
+ self.prev_config = Some((self.config.options, 0));
+ // Update the counter, which backs the ChannelUpdate timestamp, to allow the relay
+ // policy change to propagate throughout the network.
+ self.update_time_counter += 1;
+ }
+ self.config.options = *config;
+ did_channel_update
+ }
+
+ fn internal_htlc_satisfies_config(
+ &self, htlc: &msgs::UpdateAddHTLC, amt_to_forward: u64, outgoing_cltv_value: u32, config: &ChannelConfig,
+ ) -> Result<(), (&'static str, u16)> {
+ let fee = amt_to_forward.checked_mul(config.forwarding_fee_proportional_millionths as u64)
+ .and_then(|prop_fee| (prop_fee / 1000000).checked_add(config.forwarding_fee_base_msat as u64));
+ if fee.is_none() || htlc.amount_msat < fee.unwrap() ||
+ (htlc.amount_msat - fee.unwrap()) < amt_to_forward {
+ return Err((
+ "Prior hop has deviated from specified fees parameters or origin node has obsolete ones",
+ 0x1000 | 12, // fee_insufficient
+ ));
+ }
+ if (htlc.cltv_expiry as u64) < outgoing_cltv_value as u64 + config.cltv_expiry_delta as u64 {
+ return Err((
+ "Forwarding node has tampered with the intended HTLC values or origin node has an obsolete cltv_expiry_delta",
+ 0x1000 | 13, // incorrect_cltv_expiry
+ ));
+ }
+ Ok(())
+ }
+
+ /// Determines whether the parameters of an incoming HTLC to be forwarded satisfy the channel's
+ /// [`ChannelConfig`]. This first looks at the channel's current [`ChannelConfig`], and if
+ /// unsuccessful, falls back to the previous one if one exists.
+ pub fn htlc_satisfies_config(
+ &self, htlc: &msgs::UpdateAddHTLC, amt_to_forward: u64, outgoing_cltv_value: u32,
+ ) -> Result<(), (&'static str, u16)> {
+ self.internal_htlc_satisfies_config(&htlc, amt_to_forward, outgoing_cltv_value, &self.config())
+ .or_else(|err| {
+ if let Some(prev_config) = self.prev_config() {
+ self.internal_htlc_satisfies_config(htlc, amt_to_forward, outgoing_cltv_value, &prev_config)
+ } else {
+ Err(err)
+ }
+ })
+ }
+
pub fn get_feerate(&self) -> u32 {
self.feerate_per_kw
}
config: config.unwrap(),
+ prev_config: None,
+
// Note that we don't care about serializing handshake limits as we only ever serialize
// channel data after the handshake has completed.
inbound_handshake_limits_override: None,
projects / rust-lightning / blobdiff