From: Valentine Wallace Date: Wed, 20 Dec 2023 00:16:37 +0000 (-0500) Subject: Fix final blinded hop CLTV expiry on send. X-Git-Tag: v0.0.120~5^2~7 X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=commitdiff_plain;h=f1e4645edffe1c65b8ac5224ec2750d3c7fae6d6;p=rust-lightning Fix final blinded hop CLTV expiry on send. Previously, we were setting the final blinded hop's CLTV expiry height to best_block_height + total_blinded_path_cltv_delta + shadow_cltv_offset. This is incorrect, it should instead be set to best_block_height + shadow_cltv_offset only -- it doesn't make sense to include the delta for the other blinded hops in the final hop's expiry. The reason this too-high final cltv value didn't cause test failures previously is because of a 2nd bug that is fixed in an upcoming commit where the sender adds the shadow offset twice to the total path CLTV expiry. This 2nd offset meant that intermediate nodes had some buffer CLTV to subtract their delta from while still (usually) have enough leftover to meet the expiry in the final hop's onion. --- diff --git a/lightning/src/ln/onion_utils.rs b/lightning/src/ln/onion_utils.rs index ac0bb6189..2d75edd30 100644 --- a/lightning/src/ln/onion_utils.rs +++ b/lightning/src/ln/onion_utils.rs @@ -192,7 +192,7 @@ pub(super) fn build_onion_payloads(path: &Path, total_msat: u64, mut recipient_o res.push(msgs::OutboundOnionPayload::BlindedReceive { sender_intended_htlc_amt_msat: *final_value_msat, total_msat, - cltv_expiry_height: cltv, + cltv_expiry_height: cur_cltv, encrypted_tlvs: blinded_hop.encrypted_payload.clone(), intro_node_blinding_point: blinding_point.take(), });