Expose counterparty forwarding info in ChannelDetails.

Useful for constructing route hints for private channels in invoices.

Co-authored-by: Valentine Wallace <[email protected]>
Co-authored-by: Antoine Riard <[email protected]>

Author: valentinewallace

fuzz/src/router.rs

@@ -212,6 +212,7 @@ pub fn do_test<Out: test_logger::Output>(data: &[u8], out: Out) {
 								inbound_capacity_msat: 0,
 								is_live: true,
 								outbound_capacity_msat: 0,
+								counterparty_forwarding_info: None,
 							});
 						}
 						Some(&first_hops_vec[..])

lightning/src/ln/channel.rs

@@ -281,6 +281,7 @@ impl HTLCCandidate {
 	}
 }
 
+#[derive(Clone)]
 pub struct CounterpartyForwardingInfo {
 	pub fee_base_msat: u32,
 	pub fee_proportional_millionths: u32,
@@ -4126,6 +4127,11 @@ impl<Signer: Sign> Channel<Signer> {
 		}
 	}
 
+	/// Get forwarding information for the counterparty.
+	pub fn get_counterparty_forwarding_info(&self) -> Option<CounterpartyForwardingInfo> {
+		self.counterparty_forwarding_info.clone()
+	}
+
 	pub fn channel_update(&mut self, msg: &msgs::ChannelUpdate) -> Result<(), ChannelError> {
 		let usable_channel_value_msat = (self.channel_value_satoshis - self.counterparty_selected_channel_reserve_satoshis) * 1000;
 		if msg.contents.htlc_minimum_msat >  usable_channel_value_msat {

lightning/src/ln/channelmanager.rs

@@ -39,7 +39,7 @@ use chain::Watch;
 use chain::chaininterface::{BroadcasterInterface, FeeEstimator};
 use chain::channelmonitor::{ChannelMonitor, ChannelMonitorUpdate, ChannelMonitorUpdateStep, ChannelMonitorUpdateErr, HTLC_FAIL_BACK_BUFFER, CLTV_CLAIM_BUFFER, LATENCY_GRACE_PERIOD_BLOCKS, ANTI_REORG_DELAY, MonitorEvent, CLOSED_CHANNEL_UPDATE_ID};
 use chain::transaction::{OutPoint, TransactionData};
-use ln::channel::{Channel, ChannelError};
+use ln::channel::{Channel, ChannelError, CounterpartyForwardingInfo};
 use ln::features::{InitFeatures, NodeFeatures};
 use routing::router::{Route, RouteHop};
 use ln::msgs;
@@ -574,6 +574,9 @@ pub struct ChannelDetails {
 	/// True if the channel is (a) confirmed and funding_locked messages have been exchanged, (b)
 	/// the peer is connected, and (c) no monitor update failure is pending resolution.
 	pub is_live: bool,
+
+	/// Counterparty forwarding information.
+	pub counterparty_forwarding_info: Option<CounterpartyForwardingInfo>,
 }
 
 /// If a payment fails to send, it can be in one of several states. This enum is returned as the
@@ -892,6 +895,7 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
 					outbound_capacity_msat,
 					user_id: channel.get_user_id(),
 					is_live: channel.is_live(),
+					counterparty_forwarding_info: channel.get_counterparty_forwarding_info(),
 				});
 			}
 		}

lightning/src/routing/router.rs

@@ -1473,6 +1473,7 @@ mod tests {
 			outbound_capacity_msat: 100000,
 			inbound_capacity_msat: 100000,
 			is_live: true,
+			counterparty_forwarding_info: None,
 		}];
 
 		if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 100, 42, Arc::clone(&logger)) {
@@ -1790,6 +1791,7 @@ mod tests {
 			outbound_capacity_msat: 250_000_000,
 			inbound_capacity_msat: 0,
 			is_live: true,
+			counterparty_forwarding_info: None,
 		}];
 		let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, Some(&our_chans.iter().collect::<Vec<_>>()),  &Vec::new(), 100, 42, Arc::clone(&logger)).unwrap();
 		assert_eq!(route.paths[0].len(), 2);
@@ -1837,6 +1839,7 @@ mod tests {
 			outbound_capacity_msat: 250_000_000,
 			inbound_capacity_msat: 0,
 			is_live: true,
+			counterparty_forwarding_info: None,
 		}];
 		let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 100, 42, Arc::clone(&logger)).unwrap();
 		assert_eq!(route.paths[0].len(), 2);
@@ -1901,6 +1904,7 @@ mod tests {
 			outbound_capacity_msat: 250_000_000,
 			inbound_capacity_msat: 0,
 			is_live: true,
+			counterparty_forwarding_info: None,
 		}];
 		let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 100, 42, Arc::clone(&logger)).unwrap();
 		assert_eq!(route.paths[0].len(), 2);
@@ -2037,6 +2041,7 @@ mod tests {
 			outbound_capacity_msat: 250_000_000,
 			inbound_capacity_msat: 0,
 			is_live: true,
+			counterparty_forwarding_info: None,
 		}];
 		let mut last_hops = last_hops(&nodes);
 		let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[6], None, Some(&our_chans.iter().collect::<Vec<_>>()), &last_hops.iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger)).unwrap();
@@ -2165,6 +2170,7 @@ mod tests {
 			outbound_capacity_msat: 100000,
 			inbound_capacity_msat: 100000,
 			is_live: true,
+			counterparty_forwarding_info: None,
 		}];
 		let route = get_route(&source_node_id, &NetworkGraph::new(genesis_block(Network::Testnet).header.block_hash()), &target_node_id, None, Some(&our_chans.iter().collect::<Vec<_>>()), &last_hops.iter().collect::<Vec<_>>(), 100, 42, Arc::new(test_utils::TestLogger::new())).unwrap();
 
@@ -2296,6 +2302,7 @@ mod tests {
 			outbound_capacity_msat: 200_000_000,
 			inbound_capacity_msat: 0,
 			is_live: true,
+			counterparty_forwarding_info: None,
 		}];
 
 		{