test

diff --git a/lightning/src/routing/router.rs b/lightning/src/routing/router.rs
index 5f6b1261e6708da618876e937f3b076d6c0e1e0c..181ef22ba98fd0067616641f220aa44bc643b248 100644 (file)
--- a/lightning/src/routing/router.rs
+++ b/lightning/src/routing/router.rs
@@ -3523,6 +3523,66 @@ mod tests {
                        assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
                }
        }
+
+       #[test]
+       fn htlc_max_reduction_below_min() {
+               // Test that if, while walking the graph, we reduce the value being sent to meet an
+               // htlc_maximum_msat, we don't end up undershooting a later htlc_minimum_msat. In the
+               // initial version of MPP we'd accept such routes but reject them while recalculating fees,
+               // resulting in us thinking there is no possible path, even if other paths exist.
+               let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
+               let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
+
+               // We modify the graph to set the htlc_minimum of channel 2 and 4 as needed - channel 2
+               // gets an htlc_minimum_msat of 80_000 and channel 4 an htlc_maximum_msat of 90_000. We
+               // then try to send 90_000.
+               update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
+                       chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+                       short_channel_id: 2,
+                       timestamp: 2,
+                       flags: 0,
+                       cltv_expiry_delta: 0,
+                       htlc_minimum_msat: 0,
+                       htlc_maximum_msat: OptionalField::Present(80_000),
+                       fee_base_msat: 0,
+                       fee_proportional_millionths: 0,
+                       excess_data: Vec::new()
+               });
+               update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
+                       chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+                       short_channel_id: 4,
+                       timestamp: 2,
+                       flags: 0,
+                       cltv_expiry_delta: (4 << 8) | 1,
+                       htlc_minimum_msat: 90_000,
+                       htlc_maximum_msat: OptionalField::Absent,
+                       fee_base_msat: 0,
+                       fee_proportional_millionths: 0,
+                       excess_data: Vec::new()
+               });
+
+               {
+                       // Now, attempt to route 125 sats (just a bit below the capacity of 3 channels).
+                       // Our algorithm should provide us with these 3 paths.
+                       let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], Some(InvoiceFeatures::known()), None, &Vec::new(), 90_000, 42, Arc::clone(&logger)).unwrap();
+                       assert_eq!(route.paths.len(), 1);
+                       assert_eq!(route.paths[0].len(), 2);
+
+                       assert_eq!(route.paths[0][0].pubkey, nodes[7]);
+                       assert_eq!(route.paths[0][0].short_channel_id, 12);
+                       assert_eq!(route.paths[0][0].fee_msat, 90_000*2);
+                       assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
+                       assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(8));
+                       assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(12));
+
+                       assert_eq!(route.paths[0][1].pubkey, nodes[2]);
+                       assert_eq!(route.paths[0][1].short_channel_id, 13);
+                       assert_eq!(route.paths[0][1].fee_msat, 90_000);
+                       assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
+                       assert_eq!(route.paths[0][1].node_features.le_flags(), InvoiceFeatures::known().le_flags());
+                       assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
+               }
+       }
 }
 
 #[cfg(all(test, feature = "unstable"))]