f: adjust create_payment_onion for simplified path calculation

Author: arik-so

lightning/src/ln/blinded_payment_tests.rs

@@ -1674,7 +1674,7 @@ fn test_combined_trampoline_onion_creation_vectors() {
 				node_features: NodeFeatures::empty(),
 				short_channel_id: 0,
 				channel_features: ChannelFeatures::empty(),
-				fee_msat: 0,
+				fee_msat: 3_000,
 				cltv_expiry_delta: 0,
 				maybe_announced_channel: false,
 			},
@@ -1686,7 +1686,7 @@ fn test_combined_trampoline_onion_creation_vectors() {
 				short_channel_id: (572330 << 40) + (42 << 16) + 2821,
 				channel_features: ChannelFeatures::empty(),
 				fee_msat: 150_153_000,
-				cltv_expiry_delta: 24,
+				cltv_expiry_delta: 0,
 				maybe_announced_channel: false,
 			},
 		],
@@ -1695,8 +1695,8 @@ fn test_combined_trampoline_onion_creation_vectors() {
 			TrampolineHop {
 				pubkey: pubkey_from_hex("027f31ebc5462c1fdce1b737ecff52d37d75dea43ce11c74d25aa297165faa2007"),
 				node_features: Features::empty(),
-				fee_msat: 0,
-				cltv_expiry_delta: 0,
+				fee_msat: 2_500,
+				cltv_expiry_delta: 24,
 			},
 			// Dave's pubkey (the intro node needs to be duplicated)
 			TrampolineHop {
@@ -1734,10 +1734,10 @@ fn test_combined_trampoline_onion_creation_vectors() {
 	let amt_msat = 150_000_000;
 	let cur_height = 800_000;
 	let recipient_onion_fields = RecipientOnionFields::secret_only(payment_secret);
-	let (bob_onion, htlc_msat, htlc_cltv) = onion_utils::create_payment_onion_internal(&secp_ctx, &path, &session_priv, amt_msat, &recipient_onion_fields, cur_height, &associated_data, &None, None, [0; 32], Some(payment_secret), Some(outer_session_key), Some(outer_onion_prng_seed)).unwrap();
+	let (bob_onion, htlc_msat, htlc_cltv) = onion_utils::create_payment_onion_internal(&secp_ctx, &path, &session_priv, amt_msat, &recipient_onion_fields, cur_height, &associated_data, &None, None, [0; 32], Some(outer_session_key), Some(outer_onion_prng_seed)).unwrap();
 
 	let outer_onion_packet_hex = bob_onion.encode().to_lower_hex_string();
 	assert_eq!(outer_onion_packet_hex, "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");
-	assert_eq!(htlc_msat, 150_153_000);
+	assert_eq!(htlc_msat, 150_156_000);
 	assert_eq!(htlc_cltv, 800_060);
 }

lightning/src/ln/onion_utils.rs

@@ -18,7 +18,7 @@ use crate::routing::gossip::NetworkUpdate;
 use crate::routing::router::{BlindedTail, Path, RouteHop, RouteParameters, TrampolineHop};
 use crate::sign::NodeSigner;
 use crate::types::features::{ChannelFeatures, NodeFeatures};
-use crate::types::payment::{PaymentHash, PaymentPreimage, PaymentSecret};
+use crate::types::payment::{PaymentHash, PaymentPreimage};
 use crate::util::errors::{self, APIError};
 use crate::util::logger::Logger;
 use crate::util::ser::{LengthCalculatingWriter, Readable, ReadableArgs, Writeable, Writer};
@@ -1479,7 +1479,6 @@ pub fn create_payment_onion<T: secp256k1::Signing>(
 		prng_seed,
 		None,
 		None,
-		None,
 	)
 }
 
@@ -1489,8 +1488,8 @@ pub(crate) fn create_payment_onion_internal<T: secp256k1::Signing>(
 	secp_ctx: &Secp256k1<T>, path: &Path, session_priv: &SecretKey, total_msat: u64,
 	recipient_onion: &RecipientOnionFields, cur_block_height: u32, payment_hash: &PaymentHash,
 	keysend_preimage: &Option<PaymentPreimage>, invoice_request: Option<&InvoiceRequest>,
-	prng_seed: [u8; 32], secondary_payment_secret: Option<PaymentSecret>,
-	secondary_session_priv: Option<SecretKey>, secondary_prng_seed: Option<[u8; 32]>,
+	prng_seed: [u8; 32], secondary_session_priv: Option<SecretKey>,
+	secondary_prng_seed: Option<[u8; 32]>,
 ) -> Result<(msgs::OnionPacket, u64, u32), APIError> {
 	let mut outer_total_msat = total_msat;
 	let mut outer_starting_htlc_offset = cur_block_height;
@@ -1527,54 +1526,23 @@ pub(crate) fn create_payment_onion_internal<T: secp256k1::Signing>(
 		})?;
 
 		trampoline_packet_option = Some(trampoline_packet);
+
+		outer_session_priv_override = Some(secondary_session_priv.unwrap_or_else(|| {
+			let session_priv_hash = Sha256::hash(&session_priv.secret_bytes()).to_byte_array();
+			SecretKey::from_slice(&session_priv_hash[..]).expect("You broke SHA-256!")
+		}));
 	}
 
-	let (mut onion_payloads, htlc_msat, htlc_cltv) = build_onion_payloads(
+	let (onion_payloads, htlc_msat, htlc_cltv) = build_onion_payloads(
 		&path,
 		outer_total_msat,
 		recipient_onion,
 		outer_starting_htlc_offset,
 		keysend_preimage,
 		invoice_request,
+		trampoline_packet_option,
 	)?;
 
-	if !path.trampoline_hops.is_empty() {
-		let last_payload = onion_payloads.pop().ok_or(APIError::InvalidRoute {
-			err: "Non-Trampoline path needs at least one hop".to_owned(),
-		})?;
-
-		match last_payload {
-			OutboundOnionPayload::Receive { payment_data, .. } => {
-				let fee_delta = path.hops.last().map_or(0, |h| h.fee_msat);
-				let cltv_delta = path.hops.last().map_or(0, |h| h.cltv_expiry_delta);
-				let multipath_trampoline_data = payment_data.map(|d| {
-					let trampoline_payment_secret = secondary_payment_secret.unwrap_or_else(|| {
-						PaymentSecret(Sha256::hash(&d.payment_secret.0).to_byte_array())
-					});
-					let total_msat = fee_delta;
-					FinalOnionHopData { payment_secret: trampoline_payment_secret, total_msat }
-				});
-				onion_payloads.push(OutboundOnionPayload::TrampolineEntrypoint {
-					amt_to_forward: fee_delta,
-					outgoing_cltv_value: outer_starting_htlc_offset + cltv_delta,
-					multipath_trampoline_data,
-					trampoline_packet: trampoline_packet_option.unwrap(),
-				});
-			},
-			_ => {
-				return Err(APIError::InvalidRoute {
-					err: "Last non-Trampoline hop must be of type OutboundOnionPayload::Receive"
-						.to_owned(),
-				});
-			},
-		};
-
-		outer_session_priv_override = Some(secondary_session_priv.unwrap_or_else(|| {
-			let session_priv_hash = Sha256::hash(&session_priv.secret_bytes()).to_byte_array();
-			SecretKey::from_slice(&session_priv_hash[..]).expect("You broke SHA-256!")
-		}));
-	}
-
 	let outer_session_priv = outer_session_priv_override.as_ref().unwrap_or(session_priv);
 	let onion_keys = construct_onion_keys(&secp_ctx, &path, outer_session_priv).map_err(|_| {
 		APIError::InvalidRoute { err: "Pubkey along hop was maliciously selected".to_owned() }