Automatically fail intercepts back on timeout

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

diff --git a/lightning/src/ln/channelmanager.rs b/lightning/src/ln/channelmanager.rs
index 3b1bf7432fbf42b69ba4934993f48d4593c4972e..f27ca53bcf07a3c42334ee0b8cec05e681cdfc34 100644 (file)
--- a/lightning/src/ln/channelmanager.rs
+++ b/lightning/src/ln/channelmanager.rs
@@ -3067,6 +3067,9 @@ impl<M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelManager<M, T, K, F
        /// Note that LDK does not enforce fee requirements in `amt_to_forward_msat`, and will not stop
        /// you from forwarding more than you received.
        ///
+       /// Errors if the event was not handled in time, in which case the HTLC was automatically failed
+       /// backwards.
+       ///
        /// [`UserConfig::accept_intercept_htlcs`]: crate::util::config::UserConfig::accept_intercept_htlcs
        /// [`HTLCIntercepted`]: events::Event::HTLCIntercepted
        // TODO: when we move to deciding the best outbound channel at forward time, only take
@@ -3109,6 +3112,9 @@ impl<M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelManager<M, T, K, F
        /// Fails the intercepted HTLC indicated by intercept_id. Should only be called in response to
        /// an [`HTLCIntercepted`] event. See [`ChannelManager::forward_intercepted_htlc`].
        ///
+       /// Errors if the event was not handled in time, in which case the HTLC was automatically failed
+       /// backwards.
+       ///
        /// [`HTLCIntercepted`]: events::Event::HTLCIntercepted
        pub fn fail_intercepted_htlc(&self, intercept_id: InterceptId) -> Result<(), APIError> {
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(&self.total_consistency_lock, &self.persistence_notifier);
@@ -6256,7 +6262,6 @@ where
                                        if height >= htlc.cltv_expiry - HTLC_FAIL_BACK_BUFFER {
                                                let mut htlc_msat_height_data = byte_utils::be64_to_array(htlc.value).to_vec();
                                                htlc_msat_height_data.extend_from_slice(&byte_utils::be32_to_array(height));
-
                                                timed_out_htlcs.push((HTLCSource::PreviousHopData(htlc.prev_hop.clone()), payment_hash.clone(), HTLCFailReason::Reason {
                                                        failure_code: 0x4000 | 15,
                                                        data: htlc_msat_height_data
@@ -6266,6 +6271,29 @@ where
                                });
                                !htlcs.is_empty() // Only retain this entry if htlcs has at least one entry.
                        });
+
+                       let mut intercepted_htlcs = self.pending_intercepted_htlcs.lock().unwrap();
+                       intercepted_htlcs.retain(|_, htlc| {
+                               if height >= htlc.forward_info.outgoing_cltv_value - HTLC_FAIL_BACK_BUFFER {
+                                       let prev_hop_data = HTLCSource::PreviousHopData(HTLCPreviousHopData {
+                                               short_channel_id: htlc.prev_short_channel_id,
+                                               htlc_id: htlc.prev_htlc_id,
+                                               incoming_packet_shared_secret: htlc.forward_info.incoming_shared_secret,
+                                               phantom_shared_secret: None,
+                                               outpoint: htlc.prev_funding_outpoint,
+                                       });
+
+                                       let requested_forward_scid /* intercept scid */ = match htlc.forward_info.routing {
+                                               PendingHTLCRouting::Forward { short_channel_id, .. } => short_channel_id,
+                                               _ => unreachable!(),
+                                       };
+                                       timed_out_htlcs.push((prev_hop_data, htlc.forward_info.payment_hash,
+                                                       HTLCFailReason::Reason { failure_code: 0x2000 | 2, data: Vec::new() },
+                                                       HTLCDestination::InvalidForward { requested_forward_scid }));
+                                       log_trace!(self.logger, "Timing out intercepted HTLC with requested forward scid {}", requested_forward_scid);
+                                       false
+                               } else { true }
+                       });
                }
 
                self.handle_init_event_channel_failures(failed_channels);