Trampoline onion construction.

diff --git a/lightning/src/ln/msgs.rs b/lightning/src/ln/msgs.rs
index e454be89b33edb4cb7c1d2c1af0325c2862afb74..19c92e5746e51696f658d220cb2ab4fa4964cbfd 100644 (file)
--- a/lightning/src/ln/msgs.rs
+++ b/lightning/src/ln/msgs.rs
@@ -1740,6 +1740,17 @@ mod fuzzy_internal_msgs {
                }
        }
 
+       pub(crate) enum OutboundTrampolinePayload {
+               #[allow(unused)]
+               Forward {
+                       /// The value, in msat, of the payment after this hop's fee is deducted.
+                       amt_to_forward: u64,
+                       outgoing_cltv_value: u32,
+                       /// The node id to which the trampoline node must find a route
+                       outgoing_node_id: PublicKey,
+               }
+       }
+
        pub struct DecodedOnionErrorPacket {
                pub(crate) hmac: [u8; 32],
                pub(crate) failuremsg: Vec<u8>,
@@ -2597,6 +2608,22 @@ impl Writeable for OutboundOnionPayload {
        }
 }
 
+impl Writeable for OutboundTrampolinePayload {
+       fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
+               match self {
+                       Self::Forward { amt_to_forward, outgoing_cltv_value, outgoing_node_id } => {
+                               _encode_varint_length_prefixed_tlv!(w, {
+                                       (2, HighZeroBytesDroppedBigSize(*amt_to_forward), required),
+                                       (4, HighZeroBytesDroppedBigSize(*outgoing_cltv_value), required),
+                                       (14, outgoing_node_id, required)
+                               });
+                       }
+               }
+               Ok(())
+       }
+}
+
+
 impl<NS: Deref> ReadableArgs<(Option<PublicKey>, &NS)> for InboundOnionPayload where NS::Target: NodeSigner {
        fn read<R: Read>(r: &mut R, args: (Option<PublicKey>, &NS)) -> Result<Self, DecodeError> {
                let (update_add_blinding_point, node_signer) = args;

diff --git a/lightning/src/ln/onion_utils.rs b/lightning/src/ln/onion_utils.rs
index 53ef0729aa171ba56ff33ba73a55cb4ed922df83..74de4a923577269bedce2a4dccb1821d307f76b6 100644 (file)
--- a/lightning/src/ln/onion_utils.rs
+++ b/lightning/src/ln/onion_utils.rs
@@ -291,6 +291,24 @@ pub(super) fn construct_onion_packet(
        )
 }
 
+#[allow(unused)]
+pub(super) fn construct_trampoline_onion_packet(
+       payloads: Vec<msgs::OutboundTrampolinePayload>, onion_keys: Vec<OnionKeys>,
+       prng_seed: [u8; 32], associated_data: &PaymentHash, length: u16,
+) -> Result<msgs::TrampolineOnionPacket, ()> {
+       let mut packet_data = vec![0u8; length as usize];
+
+       let mut chacha = ChaCha20::new(&prng_seed, &[0; 8]);
+       chacha.process(&vec![0u8; length as usize], &mut packet_data);
+
+       construct_onion_packet_with_init_noise::<_, _>(
+               payloads,
+               onion_keys,
+               packet_data,
+               Some(associated_data),
+       )
+}
+
 #[cfg(test)]
 /// Used in testing to write bogus `BogusOnionHopData` as well as `RawOnionHopData`, which is
 /// otherwise not representable in `msgs::OnionHopData`.