From fe6564816a6275e45dcd91dd0320c30ebb1f38de Mon Sep 17 00:00:00 2001 From: Wilmer Paulino Date: Sat, 9 Mar 2024 00:53:48 -0800 Subject: [PATCH] Decode update_add_htlc onions before forwarding HTLCs This commit completes all of the groundwork necessary to decode incoming `update_add_htlc` onions once they're fully committed to by both sides. HTLCs are tracked in batches per-channel on the channel they were received on. While this path is unreachable for now, until `InboundHTLCResolution::Resolved` is replaced with `InboundHTLCResolution::Pending`, it will allow us to obtain `HTLCHandlingFailed` events for _any_ failed HTLC that comes across a channel. --- lightning/src/ln/channelmanager.rs | 141 +++++++++++++++++++++++++++++ 1 file changed, 141 insertions(+) diff --git a/lightning/src/ln/channelmanager.rs b/lightning/src/ln/channelmanager.rs index c76ba5d3..28513ebb 100644 --- a/lightning/src/ln/channelmanager.rs +++ b/lightning/src/ln/channelmanager.rs @@ -4304,6 +4304,145 @@ where Ok(()) } + fn process_pending_update_add_htlcs(&self) { + let mut decode_update_add_htlcs = new_hash_map(); + mem::swap(&mut decode_update_add_htlcs, &mut self.decode_update_add_htlcs.lock().unwrap()); + + let get_failed_htlc_destination = |outgoing_scid_opt: Option, payment_hash: PaymentHash| { + if let Some(outgoing_scid) = outgoing_scid_opt { + match self.short_to_chan_info.read().unwrap().get(&outgoing_scid) { + Some((outgoing_counterparty_node_id, outgoing_channel_id)) => + HTLCDestination::NextHopChannel { + node_id: Some(*outgoing_counterparty_node_id), + channel_id: *outgoing_channel_id, + }, + None => HTLCDestination::UnknownNextHop { + requested_forward_scid: outgoing_scid, + }, + } + } else { + HTLCDestination::FailedPayment { payment_hash } + } + }; + + 'outer_loop: for (incoming_scid, update_add_htlcs) in decode_update_add_htlcs { + let incoming_channel_details_opt = self.do_funded_channel_callback(incoming_scid, |chan: &mut Channel| { + let counterparty_node_id = chan.context.get_counterparty_node_id(); + let channel_id = chan.context.channel_id(); + let funding_txo = chan.context.get_funding_txo().unwrap(); + let user_channel_id = chan.context.get_user_id(); + let accept_underpaying_htlcs = chan.context.config().accept_underpaying_htlcs; + (counterparty_node_id, channel_id, funding_txo, user_channel_id, accept_underpaying_htlcs) + }); + let ( + incoming_counterparty_node_id, incoming_channel_id, incoming_funding_txo, + incoming_user_channel_id, incoming_accept_underpaying_htlcs + ) = if let Some(incoming_channel_details) = incoming_channel_details_opt { + incoming_channel_details + } else { + // The incoming channel no longer exists, HTLCs should be resolved onchain instead. + continue; + }; + + let mut htlc_forwards = Vec::new(); + let mut htlc_fails = Vec::new(); + for update_add_htlc in &update_add_htlcs { + let (next_hop, shared_secret, next_packet_details_opt) = match decode_incoming_update_add_htlc_onion( + &update_add_htlc, &self.node_signer, &self.logger, &self.secp_ctx + ) { + Ok(decoded_onion) => decoded_onion, + Err(htlc_fail) => { + htlc_fails.push((htlc_fail, HTLCDestination::InvalidOnion)); + continue; + }, + }; + + let is_intro_node_blinded_forward = next_hop.is_intro_node_blinded_forward(); + let outgoing_scid_opt = next_packet_details_opt.as_ref().map(|d| d.outgoing_scid); + + // Process the HTLC on the incoming channel. + match self.do_funded_channel_callback(incoming_scid, |chan: &mut Channel| { + let logger = WithChannelContext::from(&self.logger, &chan.context); + chan.can_accept_incoming_htlc( + update_add_htlc, &self.fee_estimator, &logger, + ) + }) { + Some(Ok(_)) => {}, + Some(Err((err, code))) => { + let outgoing_chan_update_opt = if let Some(outgoing_scid) = outgoing_scid_opt.as_ref() { + self.do_funded_channel_callback(*outgoing_scid, |chan: &mut Channel| { + self.get_channel_update_for_onion(*outgoing_scid, chan).ok() + }).flatten() + } else { + None + }; + let htlc_fail = self.htlc_failure_from_update_add_err( + &update_add_htlc, &incoming_counterparty_node_id, err, code, + outgoing_chan_update_opt, is_intro_node_blinded_forward, &shared_secret, + ); + let htlc_destination = get_failed_htlc_destination(outgoing_scid_opt, update_add_htlc.payment_hash); + htlc_fails.push((htlc_fail, htlc_destination)); + continue; + }, + // The incoming channel no longer exists, HTLCs should be resolved onchain instead. + None => continue 'outer_loop, + } + + // Now process the HTLC on the outgoing channel if it's a forward. + if let Some(next_packet_details) = next_packet_details_opt.as_ref() { + if let Err((err, code, chan_update_opt)) = self.can_forward_htlc( + &update_add_htlc, next_packet_details + ) { + let htlc_fail = self.htlc_failure_from_update_add_err( + &update_add_htlc, &incoming_counterparty_node_id, err, code, + chan_update_opt, is_intro_node_blinded_forward, &shared_secret, + ); + let htlc_destination = get_failed_htlc_destination(outgoing_scid_opt, update_add_htlc.payment_hash); + htlc_fails.push((htlc_fail, htlc_destination)); + continue; + } + } + + match self.construct_pending_htlc_status( + &update_add_htlc, &incoming_counterparty_node_id, shared_secret, next_hop, + incoming_accept_underpaying_htlcs, next_packet_details_opt.map(|d| d.next_packet_pubkey), + ) { + PendingHTLCStatus::Forward(htlc_forward) => { + htlc_forwards.push((htlc_forward, update_add_htlc.htlc_id)); + }, + PendingHTLCStatus::Fail(htlc_fail) => { + let htlc_destination = get_failed_htlc_destination(outgoing_scid_opt, update_add_htlc.payment_hash); + htlc_fails.push((htlc_fail, htlc_destination)); + }, + } + } + + // Process all of the forwards and failures for the channel in which the HTLCs were + // proposed to as a batch. + let pending_forwards = (incoming_scid, incoming_funding_txo, incoming_channel_id, + incoming_user_channel_id, htlc_forwards.drain(..).collect()); + self.forward_htlcs_without_forward_event(&mut [pending_forwards]); + for (htlc_fail, htlc_destination) in htlc_fails.drain(..) { + let failure = match htlc_fail { + HTLCFailureMsg::Relay(fail_htlc) => HTLCForwardInfo::FailHTLC { + htlc_id: fail_htlc.htlc_id, + err_packet: fail_htlc.reason, + }, + HTLCFailureMsg::Malformed(fail_malformed_htlc) => HTLCForwardInfo::FailMalformedHTLC { + htlc_id: fail_malformed_htlc.htlc_id, + sha256_of_onion: fail_malformed_htlc.sha256_of_onion, + failure_code: fail_malformed_htlc.failure_code, + }, + }; + self.forward_htlcs.lock().unwrap().entry(incoming_scid).or_insert(vec![]).push(failure); + self.pending_events.lock().unwrap().push_back((events::Event::HTLCHandlingFailed { + prev_channel_id: incoming_channel_id, + failed_next_destination: htlc_destination, + }, None)); + } + } + } + /// Processes HTLCs which are pending waiting on random forward delay. /// /// Should only really ever be called in response to a PendingHTLCsForwardable event. @@ -4311,6 +4450,8 @@ where pub fn process_pending_htlc_forwards(&self) { let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self); + self.process_pending_update_add_htlcs(); + let mut new_events = VecDeque::new(); let mut failed_forwards = Vec::new(); let mut phantom_receives: Vec<(u64, OutPoint, ChannelId, u128, Vec<(PendingHTLCInfo, u64)>)> = Vec::new(); -- 2.30.2