Avoid writing `ChannelManager` when hitting lnd bug 6039
[rust-lightning] / lightning / src / ln / channelmanager.rs
index e405c3a672abe6fc2359da3cac35fdc71259ca4f..0506a81c5192e945bed3f4418b0a9e6efe97cb86 100644 (file)
@@ -202,15 +202,16 @@ pub struct BlindedForward {
        /// onion payload if we're the introduction node. Useful for calculating the next hop's
        /// [`msgs::UpdateAddHTLC::blinding_point`].
        pub inbound_blinding_point: PublicKey,
-       // Another field will be added here when we support forwarding as a non-intro node.
+       /// If needed, this determines how this HTLC should be failed backwards, based on whether we are
+       /// the introduction node.
+       pub failure: BlindedFailure,
 }
 
 impl PendingHTLCRouting {
        // Used to override the onion failure code and data if the HTLC is blinded.
        fn blinded_failure(&self) -> Option<BlindedFailure> {
-               // TODO: needs update when we support forwarding blinded HTLCs as non-intro node
                match self {
-                       Self::Forward { blinded: Some(_), .. } => Some(BlindedFailure::FromIntroductionNode),
+                       Self::Forward { blinded: Some(BlindedForward { failure, .. }), .. } => Some(*failure),
                        Self::Receive { requires_blinded_error: true, .. } => Some(BlindedFailure::FromBlindedNode),
                        _ => None,
                }
@@ -305,10 +306,15 @@ pub(super) enum HTLCForwardInfo {
        },
 }
 
-// Used for failing blinded HTLCs backwards correctly.
+/// Whether this blinded HTLC is being failed backwards by the introduction node or a blinded node,
+/// which determines the failure message that should be used.
 #[derive(Clone, Copy, Debug, Hash, PartialEq, Eq)]
-enum BlindedFailure {
+pub enum BlindedFailure {
+       /// This HTLC is being failed backwards by the introduction node, and thus should be failed with
+       /// [`msgs::UpdateFailHTLC`] and error code `0x8000|0x4000|24`.
        FromIntroductionNode,
+       /// This HTLC is being failed backwards by a blinded node within the path, and thus should be
+       /// failed with [`msgs::UpdateFailMalformedHTLC`] and error code `0x8000|0x4000|24`.
        FromBlindedNode,
 }
 
@@ -3025,8 +3031,9 @@ where
 
                let is_intro_node_forward = match next_hop {
                        onion_utils::Hop::Forward {
-                               // TODO: update this when we support blinded forwarding as non-intro node
-                               next_hop_data: msgs::InboundOnionPayload::BlindedForward { .. }, ..
+                               next_hop_data: msgs::InboundOnionPayload::BlindedForward {
+                                       intro_node_blinding_point: Some(_), ..
+                               }, ..
                        } => true,
                        _ => false,
                };
@@ -3977,6 +3984,7 @@ where
                                                });
                                }
                        }
+                       mem::drop(funding_batch_states);
                        for shutdown_result in shutdown_results.drain(..) {
                                self.finish_close_channel(shutdown_result);
                        }
@@ -4371,7 +4379,7 @@ where
                                                                                incoming_packet_shared_secret: incoming_shared_secret,
                                                                                // Phantom payments are only PendingHTLCRouting::Receive.
                                                                                phantom_shared_secret: None,
-                                                                               blinded_failure: blinded.map(|_| BlindedFailure::FromIntroductionNode),
+                                                                               blinded_failure: blinded.map(|b| b.failure),
                                                                        });
                                                                        let next_blinding_point = blinded.and_then(|b| {
                                                                                let encrypted_tlvs_ss = self.node_signer.ecdh(
@@ -9022,8 +9030,6 @@ where
        }
 
        fn handle_error(&self, counterparty_node_id: &PublicKey, msg: &msgs::ErrorMessage) {
-               let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self);
-
                match &msg.data as &str {
                        "cannot co-op close channel w/ active htlcs"|
                        "link failed to shutdown" =>
@@ -9036,34 +9042,45 @@ where
                                // We're not going to bother handling this in a sensible way, instead simply
                                // repeating the Shutdown message on repeat until morale improves.
                                if !msg.channel_id.is_zero() {
-                                       let per_peer_state = self.per_peer_state.read().unwrap();
-                                       let peer_state_mutex_opt = per_peer_state.get(counterparty_node_id);
-                                       if peer_state_mutex_opt.is_none() { return; }
-                                       let mut peer_state = peer_state_mutex_opt.unwrap().lock().unwrap();
-                                       if let Some(ChannelPhase::Funded(chan)) = peer_state.channel_by_id.get(&msg.channel_id) {
-                                               if let Some(msg) = chan.get_outbound_shutdown() {
-                                                       peer_state.pending_msg_events.push(events::MessageSendEvent::SendShutdown {
-                                                               node_id: *counterparty_node_id,
-                                                               msg,
-                                                       });
-                                               }
-                                               peer_state.pending_msg_events.push(events::MessageSendEvent::HandleError {
-                                                       node_id: *counterparty_node_id,
-                                                       action: msgs::ErrorAction::SendWarningMessage {
-                                                               msg: msgs::WarningMessage {
-                                                                       channel_id: msg.channel_id,
-                                                                       data: "You appear to be exhibiting LND bug 6039, we'll keep sending you shutdown messages until you handle them correctly".to_owned()
-                                                               },
-                                                               log_level: Level::Trace,
+                                       PersistenceNotifierGuard::optionally_notify(
+                                               self,
+                                               || -> NotifyOption {
+                                                       let per_peer_state = self.per_peer_state.read().unwrap();
+                                                       let peer_state_mutex_opt = per_peer_state.get(counterparty_node_id);
+                                                       if peer_state_mutex_opt.is_none() { return NotifyOption::SkipPersistNoEvents; }
+                                                       let mut peer_state = peer_state_mutex_opt.unwrap().lock().unwrap();
+                                                       if let Some(ChannelPhase::Funded(chan)) = peer_state.channel_by_id.get(&msg.channel_id) {
+                                                               if let Some(msg) = chan.get_outbound_shutdown() {
+                                                                       peer_state.pending_msg_events.push(events::MessageSendEvent::SendShutdown {
+                                                                               node_id: *counterparty_node_id,
+                                                                               msg,
+                                                                       });
+                                                               }
+                                                               peer_state.pending_msg_events.push(events::MessageSendEvent::HandleError {
+                                                                       node_id: *counterparty_node_id,
+                                                                       action: msgs::ErrorAction::SendWarningMessage {
+                                                                               msg: msgs::WarningMessage {
+                                                                                       channel_id: msg.channel_id,
+                                                                                       data: "You appear to be exhibiting LND bug 6039, we'll keep sending you shutdown messages until you handle them correctly".to_owned()
+                                                                               },
+                                                                               log_level: Level::Trace,
+                                                                       }
+                                                               });
+                                                               // This can happen in a fairly tight loop, so we absolutely cannot trigger
+                                                               // a `ChannelManager` write here.
+                                                               return NotifyOption::SkipPersistHandleEvents;
                                                        }
-                                               });
-                                       }
+                                                       NotifyOption::SkipPersistNoEvents
+                                               }
+                                       );
                                }
                                return;
                        }
                        _ => {}
                }
 
+               let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self);
+
                if msg.channel_id.is_zero() {
                        let channel_ids: Vec<ChannelId> = {
                                let per_peer_state = self.per_peer_state.read().unwrap();
@@ -9351,6 +9368,7 @@ pub fn provided_init_features(config: &UserConfig) -> InitFeatures {
        features.set_channel_type_optional();
        features.set_scid_privacy_optional();
        features.set_zero_conf_optional();
+       features.set_route_blinding_optional();
        if config.channel_handshake_config.negotiate_anchors_zero_fee_htlc_tx {
                features.set_anchors_zero_fee_htlc_tx_optional();
        }
@@ -9496,6 +9514,7 @@ impl_writeable_tlv_based!(PhantomRouteHints, {
 
 impl_writeable_tlv_based!(BlindedForward, {
        (0, inbound_blinding_point, required),
+       (1, failure, (default_value, BlindedFailure::FromIntroductionNode)),
 });
 
 impl_writeable_tlv_based_enum!(PendingHTLCRouting,