fixup! Limit phantom invoice hints to 3

Author: freddiekrugerrand

lightning-invoice/src/utils.rs

@@ -274,13 +274,17 @@ where
 		let mut remaining_hints = false;
 
 		for hints in phantom_hints.iter() {
+			if invoice_hints.len() == 3 {
+				return invoice_hints
+			}
+
 			if hint_idx < hints.len() {
 				invoice_hints.push(hints[hint_idx].clone());
 				remaining_hints = true
 			}
 		}
 
-		if !remaining_hints || invoice_hints.len() == 3 {
+		if !remaining_hints {
 			return invoice_hints
 		}
 
@@ -1751,38 +1755,58 @@ mod test {
 
 	#[test]
 	fn test_multi_node_hints_limited_to_3() {
-		let mut chanmon_cfgs = create_chanmon_cfgs(5);
+		let mut chanmon_cfgs = create_chanmon_cfgs(6);
 		let seed_1 = [42 as u8; 32];
 		let seed_2 = [43 as u8; 32];
 		let seed_3 = [44 as u8; 32];
+		let seed_4 = [45 as u8; 32];
 		let cross_node_seed = [44 as u8; 32];
 		chanmon_cfgs[2].keys_manager.backing = PhantomKeysManager::new(&seed_1, 43, 44, &cross_node_seed);
 		chanmon_cfgs[3].keys_manager.backing = PhantomKeysManager::new(&seed_2, 43, 44, &cross_node_seed);
 		chanmon_cfgs[4].keys_manager.backing = PhantomKeysManager::new(&seed_3, 43, 44, &cross_node_seed);
-		let node_cfgs = create_node_cfgs(5, &chanmon_cfgs);
-		let node_chanmgrs = create_node_chanmgrs(5, &node_cfgs, &[None, None, None, None, None]);
-		let nodes = create_network(5, &node_cfgs, &node_chanmgrs);
+		chanmon_cfgs[5].keys_manager.backing = PhantomKeysManager::new(&seed_4, 43, 44, &cross_node_seed);
+		let node_cfgs = create_node_cfgs(6, &chanmon_cfgs);
+		let node_chanmgrs = create_node_chanmgrs(6, &node_cfgs, &[None, None, None, None, None, None]);
+		let nodes = create_network(6, &node_cfgs, &node_chanmgrs);
 
 		// Setup each phantom node with two channels from distinct peers.
-		let _chan_0_2 = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 2, 10_000, 0);
+		let chan_0_2 = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 2, 10_000, 0);
 		let chan_1_2 = create_unannounced_chan_between_nodes_with_value(&nodes, 1, 2, 20_000, 0);
 		let chan_0_3 = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 3, 20_000, 0);
 		let _chan_1_3 = create_unannounced_chan_between_nodes_with_value(&nodes, 1, 3, 10_000, 0);
 		let chan_0_4 = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 4, 20_000, 0);
 		let _chan_1_4 = create_unannounced_chan_between_nodes_with_value(&nodes, 1, 4, 10_000, 0);
+		let _chan_0_5 = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 5, 20_000, 0);
+		let _chan_1_5 = create_unannounced_chan_between_nodes_with_value(&nodes, 1, 5, 10_000, 0);
+
+		// Set invoice amount > all channels inbound so that every one is eligible for inclusion
+		// and hints will be sorted by largest inbound capacity.
+		let invoice_amt = Some(100_000_000);
 
+		// With 4 phantom nodes, assert that we include 1 hint per node, up to 3 nodes.
 		let mut scid_aliases = HashSet::new();
 		scid_aliases.insert(chan_1_2.0.short_channel_id_alias.unwrap());
 		scid_aliases.insert(chan_0_3.0.short_channel_id_alias.unwrap());
 		scid_aliases.insert(chan_0_4.0.short_channel_id_alias.unwrap());
 
-		// Since the invoice amount is above all channels inbound, every one is eligible and we'll
-		// sort by largest inbound capacity. Test that we include one channel from each of our
-		// three nodes.
 		match_multi_node_invoice_routes(
-			Some(100_000_000),
+			invoice_amt,
+			&nodes[3],
+			vec![&nodes[2], &nodes[3], &nodes[4], &nodes[5]],
+			scid_aliases,
+			false,
+		);
+
+		// With 2 phantom nodes, assert that we include no more than 3 hints.
+		let mut scid_aliases = HashSet::new();
+		scid_aliases.insert(chan_1_2.0.short_channel_id_alias.unwrap());
+		scid_aliases.insert(chan_0_3.0.short_channel_id_alias.unwrap());
+		scid_aliases.insert(chan_0_2.0.short_channel_id_alias.unwrap());
+
+		match_multi_node_invoice_routes(
+			invoice_amt,
 			&nodes[3],
-			vec![&nodes[2], &nodes[3], &nodes[4],],
+			vec![&nodes[2], &nodes[3],],
 			scid_aliases,
 			false,
 		);