Add methods to count total fees and total amount in a Route #999

* Added `get_total_fees` method to route,
to calculate all the fees paid accross each path.
* Added `get_total_amount` method to route,
to calculate the total of actual amounts paid in each path.

diff --git a/lightning/src/routing/router.rs b/lightning/src/routing/router.rs
index 13356cc1c74334193fed69be42a05b718d2ab89d..2cd937e347c07c43c5abaefa96f3725cf0b4b445 100644 (file)
--- a/lightning/src/routing/router.rs
+++ b/lightning/src/routing/router.rs
@@ -71,6 +71,26 @@ pub struct Route {
        pub paths: Vec<Vec<RouteHop>>,
 }
 
+impl Route {
+       /// Returns the total amount of fees paid on this Route.
+       /// This doesn't include any extra payment made to the recipient,
+       /// which can happen in excess of the amount passed to `get_route`'s `final_value_msat`.
+       pub fn get_total_fees(&self) -> u64 {
+               // Do not count last hop of each path since that's the full value of the payment
+               return self.paths.iter()
+                       .flat_map(|path| path.split_last().unwrap().1)
+                       .map(|hop| &hop.fee_msat)
+                       .sum();
+       }
+       /// Returns the total amount paid on this Route, excluding the fees.
+       pub fn get_total_amount(&self) -> u64 {
+               return self.paths.iter()
+                       .map(|path| path.split_last().unwrap().0)
+                       .map(|hop| &hop.fee_msat)
+                       .sum();
+       }
+}
+
 const SERIALIZATION_VERSION: u8 = 1;
 const MIN_SERIALIZATION_VERSION: u8 = 1;
 
@@ -1191,7 +1211,7 @@ pub fn get_route<L: Deref>(our_node_id: &PublicKey, network: &NetworkGraph, paye
 
 #[cfg(test)]
 mod tests {
-       use routing::router::{get_route, Route, RouteHint, RouteHintHop, RoutingFees};
+       use routing::router::{get_route, Route, RouteHint, RouteHintHop, RouteHop, RoutingFees};
        use routing::network_graph::{NetworkGraph, NetGraphMsgHandler};
        use chain::transaction::OutPoint;
        use ln::features::{ChannelFeatures, InitFeatures, InvoiceFeatures, NodeFeatures};
@@ -3425,6 +3445,7 @@ mod tests {
                                total_amount_paid_msat += path.last().unwrap().fee_msat;
                        }
                        assert_eq!(total_amount_paid_msat, 200_000);
+                       assert_eq!(route.get_total_fees(), 150_000);
                }
 
        }
@@ -3831,6 +3852,64 @@ mod tests {
                }
        }
 
+       #[test]
+       fn total_fees_single_path() {
+               let route = Route {
+                       paths: vec![vec![
+                               RouteHop {
+                                       pubkey: PublicKey::from_slice(&hex::decode("02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619").unwrap()[..]).unwrap(),
+                                       channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
+                                       short_channel_id: 0, fee_msat: 100, cltv_expiry_delta: 0 // Test vectors are garbage and not generateble from a RouteHop, we fill in payloads manually
+                               },
+                               RouteHop {
+                                       pubkey: PublicKey::from_slice(&hex::decode("0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c").unwrap()[..]).unwrap(),
+                                       channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
+                                       short_channel_id: 0, fee_msat: 150, cltv_expiry_delta: 0 // Test vectors are garbage and not generateble from a RouteHop, we fill in payloads manually
+                               },
+                               RouteHop {
+                                       pubkey: PublicKey::from_slice(&hex::decode("027f31ebc5462c1fdce1b737ecff52d37d75dea43ce11c74d25aa297165faa2007").unwrap()[..]).unwrap(),
+                                       channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
+                                       short_channel_id: 0, fee_msat: 225, cltv_expiry_delta: 0 // Test vectors are garbage and not generateble from a RouteHop, we fill in payloads manually
+                               },
+                       ]],
+               };
+
+               assert_eq!(route.get_total_fees(), 250);
+               assert_eq!(route.get_total_amount(), 225);
+       }
+
+       #[test]
+       fn total_fees_multi_path() {
+               let route = Route {
+                       paths: vec![vec![
+                               RouteHop {
+                                       pubkey: PublicKey::from_slice(&hex::decode("02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619").unwrap()[..]).unwrap(),
+                                       channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
+                                       short_channel_id: 0, fee_msat: 100, cltv_expiry_delta: 0 // Test vectors are garbage and not generateble from a RouteHop, we fill in payloads manually
+                               },
+                               RouteHop {
+                                       pubkey: PublicKey::from_slice(&hex::decode("0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c").unwrap()[..]).unwrap(),
+                                       channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
+                                       short_channel_id: 0, fee_msat: 150, cltv_expiry_delta: 0 // Test vectors are garbage and not generateble from a RouteHop, we fill in payloads manually
+                               },
+                       ],vec![
+                               RouteHop {
+                                       pubkey: PublicKey::from_slice(&hex::decode("02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619").unwrap()[..]).unwrap(),
+                                       channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
+                                       short_channel_id: 0, fee_msat: 100, cltv_expiry_delta: 0 // Test vectors are garbage and not generateble from a RouteHop, we fill in payloads manually
+                               },
+                               RouteHop {
+                                       pubkey: PublicKey::from_slice(&hex::decode("0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c").unwrap()[..]).unwrap(),
+                                       channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
+                                       short_channel_id: 0, fee_msat: 150, cltv_expiry_delta: 0 // Test vectors are garbage and not generateble from a RouteHop, we fill in payloads manually
+                               },
+                       ]],
+               };
+
+               assert_eq!(route.get_total_fees(), 200);
+               assert_eq!(route.get_total_amount(), 300);
+       }
+
        #[cfg(not(feature = "no-std"))]
        pub(super) fn random_init_seed() -> u64 {
                // Because the default HashMap in std pulls OS randomness, we can use it as a (bad) RNG.