From 795aff8da5b79dee1bea8234479cdf0ff5c98118 Mon Sep 17 00:00:00 2001 From: Antoine Riard Date: Thu, 9 Apr 2020 21:22:16 -0400 Subject: [PATCH] Document exactly our CLTV sanitization policy for incoming HTLCs --- lightning/src/ln/channelmanager.rs | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/lightning/src/ln/channelmanager.rs b/lightning/src/ln/channelmanager.rs index cbcccb82..8086fe3a 100644 --- a/lightning/src/ln/channelmanager.rs +++ b/lightning/src/ln/channelmanager.rs @@ -28,7 +28,7 @@ use secp256k1; use chain::chaininterface::{BroadcasterInterface,ChainListener,FeeEstimator}; use chain::transaction::OutPoint; use ln::channel::{Channel, ChannelError}; -use ln::channelmonitor::{ChannelMonitor, ChannelMonitorUpdate, ChannelMonitorUpdateErr, ManyChannelMonitor, CLTV_CLAIM_BUFFER, LATENCY_GRACE_PERIOD_BLOCKS, ANTI_REORG_DELAY, HTLC_FAIL_BACK_BUFFER}; +use ln::channelmonitor::{ChannelMonitor, ChannelMonitorUpdate, ChannelMonitorUpdateErr, ManyChannelMonitor, HTLC_FAIL_BACK_BUFFER, CLTV_CLAIM_BUFFER, LATENCY_GRACE_PERIOD_BLOCKS, ANTI_REORG_DELAY}; use ln::features::{InitFeatures, NodeFeatures}; use ln::router::{Route, RouteHop}; use ln::msgs; @@ -1163,8 +1163,9 @@ impl ChannelMan break Some(("Forwarding node has tampered with the intended HTLC values or origin node has an obsolete cltv_expiry_delta", 0x1000 | 13, Some(self.get_channel_update(chan).unwrap()))); } let cur_height = self.latest_block_height.load(Ordering::Acquire) as u32 + 1; - // We want to have at least LATENCY_GRACE_PERIOD_BLOCKS to fail prior to going on chain CLAIM_BUFFER blocks before expiration - if msg.cltv_expiry <= cur_height + CLTV_CLAIM_BUFFER + LATENCY_GRACE_PERIOD_BLOCKS as u32 { // expiry_too_soon + // Theoretically, channel counterparty shouldn't send us a HTLC expiring now, but we want to be robust wrt to counterparty + // packet sanitization (see HTLC_FAIL_BACK_BUFFER rational) + if msg.cltv_expiry <= cur_height + HTLC_FAIL_BACK_BUFFER as u32 { // expiry_too_soon break Some(("CLTV expiry is too close", 0x1000 | 14, Some(self.get_channel_update(chan).unwrap()))); } if msg.cltv_expiry > cur_height + CLTV_FAR_FAR_AWAY as u32 { // expiry_too_far -- 2.30.2