Fix off-by-one finalized transaction locktime

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

diff --git a/lightning/src/ln/channelmanager.rs b/lightning/src/ln/channelmanager.rs
index 5074b7cb7d35ec5af04ffd0c93b2fe7f58c2606d..e8261f686264b884b7679185ee1543292c9193b5 100644 (file)
--- a/lightning/src/ln/channelmanager.rs
+++ b/lightning/src/ln/channelmanager.rs
@@ -3006,10 +3006,11 @@ where
                }
                {
                        let height = self.best_block.read().unwrap().height();
-                       // Transactions are evaluated as final by network mempools at the next block. However, the modules
-                       // constituting our Lightning node might not have perfect sync about their blockchain views. Thus, if
-                       // the wallet module is in advance on the LDK view, allow one more block of headroom.
-                       if !funding_transaction.input.iter().all(|input| input.sequence == Sequence::MAX) && LockTime::from(funding_transaction.lock_time).is_block_height() && funding_transaction.lock_time.0 > height + 2 {
+                       // Transactions are evaluated as final by network mempools if their locktime is strictly
+                       // lower than the next block height. However, the modules constituting our Lightning
+                       // node might not have perfect sync about their blockchain views. Thus, if the wallet
+                       // module is ahead of LDK, only allow one more block of headroom.
+                       if !funding_transaction.input.iter().all(|input| input.sequence == Sequence::MAX) && LockTime::from(funding_transaction.lock_time).is_block_height() && funding_transaction.lock_time.0 > height + 1 {
                                return Err(APIError::APIMisuseError {
                                        err: "Funding transaction absolute timelock is non-final".to_owned()
                                });