Expose API to update a channel's ChannelConfig
authorWilmer Paulino <wilmer.paulino@gmail.com>
Tue, 14 Jun 2022 23:41:32 +0000 (16:41 -0700)
committerWilmer Paulino <wilmer.paulino@gmail.com>
Mon, 20 Jun 2022 20:12:48 +0000 (13:12 -0700)
A new `update_channel_config` method is exposed on the `ChannelManger`
to update the `ChannelConfig` for a set of channels atomically. New
`ChannelUpdate` events are generated for each eligible channel.

Note that as currently implemented, a buggy and/or
auto-policy-management client could spam the network with updates as
there is no rate-limiting in place. This could already be done with
`broadcast_node_announcement`, though users are less inclined to update
that as frequently as its data is mostly static.

lightning/src/ln/channel.rs
lightning/src/ln/channelmanager.rs
lightning/src/ln/onion_route_tests.rs

index 846bfd01be843c6c60c4cdfd724bfa9e7301f71a..ab26cea33f092187756a72e42d091952ed98ef7b 100644 (file)
@@ -4491,12 +4491,27 @@ impl<Signer: Sign> Channel<Signer> {
                self.config.options.max_dust_htlc_exposure_msat
        }
 
-
        /// Returns the current [`ChannelConfig`] applied to the channel.
        pub fn config(&self) -> ChannelConfig {
                self.config.options
        }
 
+       /// Updates the channel's config. A bool is returned indicating whether the config update
+       /// applied resulted in a new ChannelUpdate message.
+       pub fn update_config(&mut self, config: &ChannelConfig) -> bool {
+               let did_channel_update =
+                       self.config.options.forwarding_fee_proportional_millionths != config.forwarding_fee_proportional_millionths ||
+                       self.config.options.forwarding_fee_base_msat != config.forwarding_fee_base_msat ||
+                       self.config.options.cltv_expiry_delta != config.cltv_expiry_delta;
+               if did_channel_update {
+                       // Update the counter, which backs the ChannelUpdate timestamp, to allow the relay
+                       // policy change to propagate throughout the network.
+                       self.update_time_counter += 1;
+               }
+               self.config.options = *config;
+               did_channel_update
+       }
+
        pub fn get_feerate(&self) -> u32 {
                self.feerate_per_kw
        }
index 6913e1f7ed7ae450ecc463f5374ef3a707cfb26f..58d84eb0dbb078ae5f0ab0d1b11393c7601a7508 100644 (file)
@@ -2919,6 +2919,73 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
                }
        }
 
+       /// Atomically updates the [`ChannelConfig`] for the given channels.
+       ///
+       /// Once the updates are applied, each eligible channel (advertised with a known short channel
+       /// ID and a change in [`forwarding_fee_proportional_millionths`], [`forwarding_fee_base_msat`],
+       /// or [`cltv_expiry_delta`]) has a [`BroadcastChannelUpdate`] event message generated
+       /// containing the new [`ChannelUpdate`] message which should be broadcast to the network.
+       ///
+       /// Returns [`ChannelUnavailable`] when a channel is not found or an incorrect
+       /// `counterparty_node_id` is provided.
+       ///
+       /// Returns [`APIMisuseError`] when a [`cltv_expiry_delta`] update is to be applied with a value
+       /// below [`MIN_CLTV_EXPIRY_DELTA`].
+       ///
+       /// If an error is returned, none of the updates should be considered applied.
+       ///
+       /// [`forwarding_fee_proportional_millionths`]: ChannelConfig::forwarding_fee_proportional_millionths
+       /// [`forwarding_fee_base_msat`]: ChannelConfig::forwarding_fee_base_msat
+       /// [`cltv_expiry_delta`]: ChannelConfig::cltv_expiry_delta
+       /// [`BroadcastChannelUpdate`]: events::MessageSendEvent::BroadcastChannelUpdate
+       /// [`ChannelUpdate`]: msgs::ChannelUpdate
+       /// [`ChannelUnavailable`]: APIError::ChannelUnavailable
+       /// [`APIMisuseError`]: APIError::APIMisuseError
+       pub fn update_channel_config(
+               &self, counterparty_node_id: &PublicKey, channel_ids: &[[u8; 32]], config: &ChannelConfig,
+       ) -> Result<(), APIError> {
+               if config.cltv_expiry_delta < MIN_CLTV_EXPIRY_DELTA {
+                       return Err(APIError::APIMisuseError {
+                               err: format!("The chosen CLTV expiry delta is below the minimum of {}", MIN_CLTV_EXPIRY_DELTA),
+                       });
+               }
+
+               let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(
+                       &self.total_consistency_lock, &self.persistence_notifier,
+               );
+               {
+                       let mut channel_state_lock = self.channel_state.lock().unwrap();
+                       let channel_state = &mut *channel_state_lock;
+                       for channel_id in channel_ids {
+                               let channel_counterparty_node_id = channel_state.by_id.get(channel_id)
+                                       .ok_or(APIError::ChannelUnavailable {
+                                               err: format!("Channel with ID {} was not found", log_bytes!(*channel_id)),
+                                       })?
+                                       .get_counterparty_node_id();
+                               if channel_counterparty_node_id != *counterparty_node_id {
+                                       return Err(APIError::APIMisuseError {
+                                               err: "counterparty node id mismatch".to_owned(),
+                                       });
+                               }
+                       }
+                       for channel_id in channel_ids {
+                               let channel = channel_state.by_id.get_mut(channel_id).unwrap();
+                               if !channel.update_config(config) {
+                                       continue;
+                               }
+                               if let Ok(msg) = self.get_channel_update_for_broadcast(channel) {
+                                       channel_state.pending_msg_events.push(events::MessageSendEvent::BroadcastChannelUpdate { msg });
+                               } else if let Ok(msg) = self.get_channel_update_for_unicast(channel) {
+                                       channel_state.pending_msg_events.push(events::MessageSendEvent::SendChannelUpdate {
+                                               node_id: channel.get_counterparty_node_id(),
+                                               msg,
+                                       });
+                               }
+                       }
+               }
+               Ok(())
+       }
+
        /// Processes HTLCs which are pending waiting on random forward delay.
        ///
        /// Should only really ever be called in response to a PendingHTLCsForwardable event.
index 1e340d4a15e0f06a998c541d949b808e5f5dc672..27c701bcfbd5e755e33e4376ccf104e8fffef14c 100644 (file)
 //! These tests work by standing up full nodes and route payments across the network, checking the
 //! returned errors decode to the correct thing.
 
-use chain::channelmonitor::{CLTV_CLAIM_BUFFER, LATENCY_GRACE_PERIOD_BLOCKS};
+use chain::channelmonitor::{ChannelMonitor, CLTV_CLAIM_BUFFER, LATENCY_GRACE_PERIOD_BLOCKS};
 use chain::keysinterface::{KeysInterface, Recipient};
 use ln::{PaymentHash, PaymentSecret};
-use ln::channelmanager::{HTLCForwardInfo, CLTV_FAR_FAR_AWAY, MIN_CLTV_EXPIRY_DELTA, PendingHTLCInfo, PendingHTLCRouting};
+use ln::channelmanager::{ChannelManager, ChannelManagerReadArgs, HTLCForwardInfo, CLTV_FAR_FAR_AWAY, MIN_CLTV_EXPIRY_DELTA, PendingHTLCInfo, PendingHTLCRouting};
 use ln::onion_utils;
 use routing::gossip::{NetworkUpdate, RoutingFees, NodeId};
 use routing::router::{get_route, PaymentParameters, Route, RouteHint, RouteHintHop};
@@ -23,9 +23,10 @@ use ln::msgs;
 use ln::msgs::{ChannelMessageHandler, ChannelUpdate, OptionalField};
 use ln::wire::Encode;
 use util::events::{Event, MessageSendEvent, MessageSendEventsProvider};
-use util::ser::{Writeable, Writer};
+use util::ser::{ReadableArgs, Writeable, Writer};
 use util::{byte_utils, test_utils};
-use util::config::UserConfig;
+use util::config::{UserConfig, ChannelConfig};
+use util::errors::APIError;
 
 use bitcoin::hash_types::BlockHash;
 
@@ -506,8 +507,6 @@ fn test_onion_failure() {
        let preimage = send_along_route(&nodes[0], bogus_route, &[&nodes[1], &nodes[2]], amt_to_forward+1).0;
        claim_payment(&nodes[0], &[&nodes[1], &nodes[2]], preimage);
 
-       //TODO: with new config API, we will be able to generate both valid and
-       //invalid channel_update cases.
        let short_channel_id = channels[0].0.contents.short_channel_id;
        run_onion_failure_test("fee_insufficient", 0, &nodes, &route, &payment_hash, &payment_secret, |msg| {
                msg.amount_msat -= 1;
@@ -594,6 +593,183 @@ fn test_onion_failure() {
        }, true, Some(23), None, None);
 }
 
+fn do_test_onion_failure_stale_channel_update(announced_channel: bool) {
+       // Create a network of three nodes and two channels connecting them. We'll be updating the
+       // HTLC relay policy of the second channel, causing forwarding failures at the first hop.
+       let mut config = UserConfig::default();
+       config.channel_handshake_config.announced_channel = announced_channel;
+       config.channel_handshake_limits.force_announced_channel_preference = false;
+       config.accept_forwards_to_priv_channels = !announced_channel;
+       let chanmon_cfgs = create_chanmon_cfgs(3);
+       let node_cfgs = create_node_cfgs(3, &chanmon_cfgs);
+       let node_chanmgrs = create_node_chanmgrs(3, &node_cfgs, &[None, Some(config), None]);
+       let mut nodes = create_network(3, &node_cfgs, &node_chanmgrs);
+
+       let other_channel = create_chan_between_nodes(
+               &nodes[0], &nodes[1], InitFeatures::known(), InitFeatures::known(),
+       );
+       let channel_to_update = if announced_channel {
+               let channel = create_announced_chan_between_nodes(
+                       &nodes, 1, 2, InitFeatures::known(), InitFeatures::known(),
+               );
+               (channel.2, channel.0.contents.short_channel_id)
+       } else {
+               let channel = create_unannounced_chan_between_nodes_with_value(
+                       &nodes, 1, 2, 100000, 10001, InitFeatures::known(), InitFeatures::known(),
+               );
+               (channel.0.channel_id, channel.0.short_channel_id_alias.unwrap())
+       };
+       let channel_to_update_counterparty = &nodes[2].node.get_our_node_id();
+
+       let default_config = ChannelConfig::default();
+
+       // A test payment should succeed as the ChannelConfig has not been changed yet.
+       const PAYMENT_AMT: u64 = 40000;
+       let (route, payment_hash, payment_preimage, payment_secret) = if announced_channel {
+               get_route_and_payment_hash!(nodes[0], nodes[2], PAYMENT_AMT)
+       } else {
+               let hop_hints = vec![RouteHint(vec![RouteHintHop {
+                       src_node_id: nodes[1].node.get_our_node_id(),
+                       short_channel_id: channel_to_update.1,
+                       fees: RoutingFees {
+                               base_msat: default_config.forwarding_fee_base_msat,
+                               proportional_millionths: default_config.forwarding_fee_proportional_millionths,
+                       },
+                       cltv_expiry_delta: default_config.cltv_expiry_delta,
+                       htlc_maximum_msat: None,
+                       htlc_minimum_msat: None,
+               }])];
+               let payment_params = PaymentParameters::from_node_id(*channel_to_update_counterparty)
+                       .with_features(InvoiceFeatures::known())
+                       .with_route_hints(hop_hints);
+               get_route_and_payment_hash!(nodes[0], nodes[2], payment_params, PAYMENT_AMT, TEST_FINAL_CLTV)
+       };
+       send_along_route_with_secret(&nodes[0], route.clone(), &[&[&nodes[1], &nodes[2]]], PAYMENT_AMT,
+               payment_hash, payment_secret);
+       claim_payment(&nodes[0], &[&nodes[1], &nodes[2]], payment_preimage);
+
+       // Closure to update and retrieve the latest ChannelUpdate.
+       let update_and_get_channel_update = |config: &ChannelConfig, expect_new_update: bool,
+               prev_update: Option<&msgs::ChannelUpdate>| -> Option<msgs::ChannelUpdate> {
+               nodes[1].node.update_channel_config(
+                       channel_to_update_counterparty, &[channel_to_update.0], config,
+               ).unwrap();
+               let events = nodes[1].node.get_and_clear_pending_msg_events();
+               assert_eq!(events.len(), expect_new_update as usize);
+               if !expect_new_update {
+                       return None;
+               }
+               let new_update = match &events[0] {
+                       MessageSendEvent::BroadcastChannelUpdate { msg } => {
+                               assert!(announced_channel);
+                               msg.clone()
+                       },
+                       MessageSendEvent::SendChannelUpdate { node_id, msg } => {
+                               assert_eq!(node_id, channel_to_update_counterparty);
+                               assert!(!announced_channel);
+                               msg.clone()
+                       },
+                       _ => panic!("expected Broadcast/SendChannelUpdate event"),
+               };
+               if prev_update.is_some() {
+                       assert!(new_update.contents.timestamp > prev_update.unwrap().contents.timestamp)
+               }
+               Some(new_update)
+       };
+
+       // We'll be attempting to route payments using the default ChannelUpdate for channels. This will
+       // lead to onion failures at the first hop once we update the ChannelConfig for the
+       // second hop.
+       let expect_onion_failure = |name: &str, error_code: u16, channel_update: &msgs::ChannelUpdate| {
+               let short_channel_id = channel_to_update.1;
+               let network_update = NetworkUpdate::ChannelUpdateMessage { msg: channel_update.clone() };
+               run_onion_failure_test(
+                       name, 0, &nodes, &route, &payment_hash, &payment_secret, |_| {}, || {}, true,
+                       Some(error_code), Some(network_update), Some(short_channel_id),
+               );
+       };
+
+       // Updates to cltv_expiry_delta below MIN_CLTV_EXPIRY_DELTA should fail with APIMisuseError.
+       let mut invalid_config = default_config.clone();
+       invalid_config.cltv_expiry_delta = 0;
+       match nodes[1].node.update_channel_config(
+               channel_to_update_counterparty, &[channel_to_update.0], &invalid_config,
+       ) {
+               Err(APIError::APIMisuseError{ .. }) => {},
+               _ => panic!("unexpected result applying invalid cltv_expiry_delta"),
+       }
+
+       // Increase the base fee which should trigger a new ChannelUpdate.
+       let mut config = nodes[1].node.list_usable_channels().iter()
+               .find(|channel| channel.channel_id == channel_to_update.0).unwrap()
+               .config.unwrap();
+       config.forwarding_fee_base_msat = u32::max_value();
+       let msg = update_and_get_channel_update(&config, true, None).unwrap();
+       expect_onion_failure("fee_insufficient", UPDATE|12, &msg);
+
+       // Redundant updates should not trigger a new ChannelUpdate.
+       assert!(update_and_get_channel_update(&config, false, None).is_none());
+
+       // Similarly, updates that do not have an affect on ChannelUpdate should not trigger a new one.
+       config.force_close_avoidance_max_fee_satoshis *= 2;
+       assert!(update_and_get_channel_update(&config, false, None).is_none());
+
+       // Reset the base fee to the default and increase the proportional fee which should trigger a
+       // new ChannelUpdate.
+       config.forwarding_fee_base_msat = default_config.forwarding_fee_base_msat;
+       config.cltv_expiry_delta = u16::max_value();
+       let msg = update_and_get_channel_update(&config, true, Some(&msg)).unwrap();
+       expect_onion_failure("incorrect_cltv_expiry", UPDATE|13, &msg);
+
+       // Reset the proportional fee and increase the CLTV expiry delta which should trigger a new
+       // ChannelUpdate.
+       config.cltv_expiry_delta = default_config.cltv_expiry_delta;
+       config.forwarding_fee_proportional_millionths = u32::max_value();
+       let msg = update_and_get_channel_update(&config, true, Some(&msg)).unwrap();
+       expect_onion_failure("fee_insufficient", UPDATE|12, &msg);
+
+       // To test persistence of the updated config, we'll re-initialize the ChannelManager.
+       let config_after_restart = {
+               let persister = test_utils::TestPersister::new();
+               let chain_monitor = test_utils::TestChainMonitor::new(
+                       Some(nodes[1].chain_source), nodes[1].tx_broadcaster.clone(), nodes[1].logger,
+                       node_cfgs[1].fee_estimator, &persister, nodes[1].keys_manager,
+               );
+
+               let mut chanmon_1 = <(_, ChannelMonitor<_>)>::read(
+                       &mut &get_monitor!(nodes[1], other_channel.3).encode()[..], nodes[1].keys_manager,
+               ).unwrap().1;
+               let mut chanmon_2 = <(_, ChannelMonitor<_>)>::read(
+                       &mut &get_monitor!(nodes[1], channel_to_update.0).encode()[..], nodes[1].keys_manager,
+               ).unwrap().1;
+               let mut channel_monitors = HashMap::new();
+               channel_monitors.insert(chanmon_1.get_funding_txo().0, &mut chanmon_1);
+               channel_monitors.insert(chanmon_2.get_funding_txo().0, &mut chanmon_2);
+
+               let chanmgr = <(_, ChannelManager<_, _, _, _, _, _>)>::read(
+                       &mut &nodes[1].node.encode()[..], ChannelManagerReadArgs {
+                               default_config: *nodes[1].node.get_current_default_configuration(),
+                               keys_manager: nodes[1].keys_manager,
+                               fee_estimator: node_cfgs[1].fee_estimator,
+                               chain_monitor: &chain_monitor,
+                               tx_broadcaster: nodes[1].tx_broadcaster.clone(),
+                               logger: nodes[1].logger,
+                               channel_monitors: channel_monitors,
+                       },
+               ).unwrap().1;
+               chanmgr.list_channels().iter()
+                       .find(|channel| channel.channel_id == channel_to_update.0).unwrap()
+                       .config.unwrap()
+       };
+       assert_eq!(config, config_after_restart);
+}
+
+#[test]
+fn test_onion_failure_stale_channel_update() {
+       do_test_onion_failure_stale_channel_update(false);
+       do_test_onion_failure_stale_channel_update(true);
+}
+
 #[test]
 fn test_default_to_onion_payload_tlv_format() {
        // Tests that we default to creating tlv format onion payloads when no `NodeAnnouncementInfo`