[bug]: routerClient.BuildRoute does not consider inbound fees #8814
Description
Background
Using routerClient.BuildRoute to create a route does not produce routes that use any fee discounts.
Your environment
- LND 0.18.0-beta commit=v0.18.0-beta (commit: fed7609)
Steps to reproduce
Find a route via lnClient.QueryRoutes until one is found with a hop that has negative inbound fees. Reconstruct same route using the pubkeys from the original route that QueryRoutes returned:
for _, hop := range originalRoute.Hops {
pk, _ := hex.DecodeString(hop.PubKey)
pks = append(pks, pk)
}
sameRoute, err := satty.routerClient.BuildRoute(ctx, &routerrpc.BuildRouteRequest{
AmtMsat: sats * 1000,
HopPubkeys: pks,
FinalCltvDelta: final,
})
Expected behaviour
routerClient.BuildRoute should return the same route as the lnClient.QueryRoutes one with the same discounted fees.
Actual behaviour
Code:
fmt.Printf("via lnClient.QueryRoutes\n")
for n, hop := range originalRoute.Hops {
fmt.Printf("%d - %s | Hop fee: %d\n", n, hop.PubKey, hop.FeeMsat)
}
fmt.Printf("Total fee: %d\n", originalRoute.TotalFeesMsat)
fmt.Printf("\n----\n\n")
fmt.Printf("via routerClient.BuildRoute, same pubkeys\n")
for n, hop := range sameRoute.Route.Hops {
fmt.Printf("%d - %s | Hop fee: %d\n", n, hop.PubKey, hop.FeeMsat)
}
fmt.Printf("Total fee: %d\n", sameRoute.Route.TotalFeesMsat)
Debug output:
via lnClient.QueryRoutes
0 - 02e46fce29587e4a8d39da2cf21f032536c1ced45e82e4ba04f127ee7337783b38 | Hop fee: 0
1 - 03423790614f023e3c0cdaa654a3578e919947e4c3a14bf5044e7c787ebd11af1a | Hop fee: 0
2 - 033b63e4a9931dc151037acbce12f4f8968c86f5655cf102bbfa85a26bd4adc6d9 | Hop fee: 240771
3 - 037f990e61acee8a7697966afd29dd88f3b1f8a7b14d625c4f8742bd952003a590 | Hop fee: 1185
4 - 027ce055380348d7812d2ae7745701c9f93e70c1adeb2657f053f91df4f2843c71 | Hop fee: 51340
5 - 021c97a90a411ff2b10dc2a8e32de2f29d2fa49d41bfbb52bd416e460db0747d0d | Hop fee: 1000
6 - 03a93b87bf9f052b8e862d51ebbac4ce5e97b5f4137563cd5128548d7f5978dda9 | Hop fee: 0
Total fee: 294296
----
via routerClient.BuildRoute, same pubkeys
0 - 02e46fce29587e4a8d39da2cf21f032536c1ced45e82e4ba04f127ee7337783b38 | Hop fee: 0
1 - 03423790614f023e3c0cdaa654a3578e919947e4c3a14bf5044e7c787ebd11af1a | Hop fee: 0
2 - 033b63e4a9931dc151037acbce12f4f8968c86f5655cf102bbfa85a26bd4adc6d9 | Hop fee: 240945
3 - 037f990e61acee8a7697966afd29dd88f3b1f8a7b14d625c4f8742bd952003a590 | Hop fee: 1185
4 - 027ce055380348d7812d2ae7745701c9f93e70c1adeb2657f053f91df4f2843c71 | Hop fee: 185156
5 - 021c97a90a411ff2b10dc2a8e32de2f29d2fa49d41bfbb52bd416e460db0747d0d | Hop fee: 1000
6 - 03a93b87bf9f052b8e862d51ebbac4ce5e97b5f4137563cd5128548d7f5978dda9 | Hop fee: 0
Total fee: 428286