Trampoline onion construction vectors

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>,
@@ -1798,7 +1809,7 @@ pub struct TrampolineOnionPacket {
 	// Unlike the onion packets used for payments, Trampoline onion packets have to be shorter than
 	// 1300 bytes. The expected default is 650 bytes.
 	// TODO: if 650 ends up being the most common size, optimize this to be:
-	// enum { ThirteenHundred([u8; 650]), VarLen(Vec<u8>) }
+	// enum { SixFifty([u8; 650]), VarLen(Vec<u8>) }
 	pub hop_data: Vec<u8>,
 	/// HMAC to verify the integrity of hop_data
 	pub hmac: [u8; 32],
@@ -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;

lightning/src/ln/onion_route_tests.rs

@@ -22,7 +22,7 @@ use crate::routing::gossip::{NetworkUpdate, RoutingFees};
 use crate::routing::router::{get_route, PaymentParameters, Route, RouteParameters, RouteHint, RouteHintHop};
 use crate::ln::features::{InitFeatures, Bolt11InvoiceFeatures};
 use crate::ln::msgs;
-use crate::ln::msgs::{ChannelMessageHandler, ChannelUpdate};
+use crate::ln::msgs::{ChannelMessageHandler, ChannelUpdate, OutboundTrampolinePayload};
 use crate::ln::wire::Encode;
 use crate::util::ser::{Writeable, Writer, BigSize};
 use crate::util::test_utils;
@@ -35,11 +35,12 @@ use bitcoin::hashes::hmac::{Hmac, HmacEngine};
 use bitcoin::hashes::sha256::Hash as Sha256;
 
 use bitcoin::secp256k1;
-use bitcoin::secp256k1::{Secp256k1, SecretKey};
+use bitcoin::secp256k1::{PublicKey, Secp256k1, SecretKey};
 
 use crate::io;
 use crate::prelude::*;
 use core::default::Default;
+use bitcoin::hashes::hex::FromHex;
 
 use crate::ln::functional_test_utils::*;
 
@@ -966,6 +967,25 @@ fn test_always_create_tlv_format_onion_payloads() {
 	}
 }
 
+#[test]
+fn test_trampoline_onion_payload_serialization() {
+	// As per https://github.com/lightning/bolts/blob/c01d2e6267d4a8d1095f0f1188970055a9a22d29/bolt04/trampoline-payment-onion-test.json#L3
+	let trampoline_payload = OutboundTrampolinePayload::Forward {
+		amt_to_forward: 100000000,
+		outgoing_cltv_value: 800000,
+		outgoing_node_id: PublicKey::from_slice(&<Vec<u8>>::from_hex("02edabbd16b41c8371b92ef2f04c1185b4f03b6dcd52ba9b78d9d7c89c8f221145").unwrap()).unwrap(),
+	};
+
+	let slice_to_hex = |slice: &[u8]| {
+		slice.iter()
+			.map(|b| format!("{:02x}", b).to_string())
+			.collect::<String>()
+	};
+
+	let carol_payload_hex = slice_to_hex(&trampoline_payload.encode());
+	assert_eq!(carol_payload_hex, "2e020405f5e10004030c35000e2102edabbd16b41c8371b92ef2f04c1185b4f03b6dcd52ba9b78d9d7c89c8f221145");
+}
+
 fn do_test_fail_htlc_backwards_with_reason(failure_code: FailureCode) {
 
 	let chanmon_cfgs = create_chanmon_cfgs(2);

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`.