Merge pull request #1169 from TheBlueMatt/2021-11-fix-update-announcements

[rust-lightning] / lightning / src / ln / channel.rs

diff --git a/lightning/src/ln/channel.rs b/lightning/src/ln/channel.rs
index 3b10cba549823566bd658e143bf1093fba5c62c0..0cdcb0c14c2b0665f45c272e244f714208e29001 100644 (file)
--- a/lightning/src/ln/channel.rs
+++ b/lightning/src/ln/channel.rs
@@ -481,9 +481,14 @@ pub(super) struct Channel<Signer: Sign> {
        holding_cell_update_fee: Option<u32>,
        next_holder_htlc_id: u64,
        next_counterparty_htlc_id: u64,
-       update_time_counter: u32,
        feerate_per_kw: u32,
 
+       /// The timestamp set on our latest `channel_update` message for this channel. It is updated
+       /// when the channel is updated in ways which may impact the `channel_update` message or when a
+       /// new block is received, ensuring it's always at least moderately close to the current real
+       /// time.
+       update_time_counter: u32,
+
        #[cfg(debug_assertions)]
        /// Max to_local and to_remote outputs in a locally-generated commitment transaction
        holder_max_commitment_tx_output: Mutex<(u64, u64)>,
@@ -862,8 +867,12 @@ impl<Signer: Sign> Channel<Signer> {
                where F::Target: FeeEstimator
        {
                let lower_limit = fee_estimator.get_est_sat_per_1000_weight(ConfirmationTarget::Background);
-               if feerate_per_kw < lower_limit {
-                       return Err(ChannelError::Close(format!("Peer's feerate much too low. Actual: {}. Our expected lower limit: {}", feerate_per_kw, lower_limit)));
+               // Some fee estimators round up to the next full sat/vbyte (ie 250 sats per kw), causing
+               // occasional issues with feerate disagreements between an initiator that wants a feerate
+               // of 1.1 sat/vbyte and a receiver that wants 1.1 rounded up to 2. Thus, we always add 250
+               // sat/kw before the comparison here.
+               if feerate_per_kw + 250 < lower_limit {
+                       return Err(ChannelError::Close(format!("Peer's feerate much too low. Actual: {}. Our expected lower limit: {} (- 250)", feerate_per_kw, lower_limit)));
                }
                // We only bound the fee updates on the upper side to prevent completely absurd feerates,
                // always accepting up to 25 sat/vByte or 10x our fee estimator's "High Priority" fee.
@@ -4188,6 +4197,7 @@ impl<Signer: Sign> Channel<Signer> {
        }
 
        pub fn set_channel_update_status(&mut self, status: ChannelUpdateStatus) {
+               self.update_time_counter += 1;
                self.channel_update_status = status;
        }