From: Matt Corallo <git@bluematt.me>
Date: Tue, 7 Dec 2021 17:23:42 +0000 (+0000)
Subject: Reduce force-closures with user fee estimators which round poorly
X-Git-Tag: v0.0.104~11^2
X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=commitdiff_plain;h=refs%2Fheads%2F2021-12-less-force-close;p=rust-lightning

Reduce force-closures with user fee estimators which round poorly

See comment for more
---

diff --git a/lightning/src/ln/channel.rs b/lightning/src/ln/channel.rs
index ae5df9a15..0ab687521 100644
--- a/lightning/src/ln/channel.rs
+++ b/lightning/src/ln/channel.rs
@@ -862,8 +862,12 @@ 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.