create_payment_onion returns ApiError and is used in send_payment_along_path

Author: Evanfeenstra

lightning/src/ln/channelmanager.rs

@@ -3420,12 +3420,10 @@ where
 		let prng_seed = self.entropy_source.get_secure_random_bytes();
 		let session_priv = SecretKey::from_slice(&session_priv_bytes[..]).expect("RNG is busted");
 
-		let onion_keys = onion_utils::construct_onion_keys(&self.secp_ctx, &path, &session_priv)
-			.map_err(|_| APIError::InvalidRoute{err: "Pubkey along hop was maliciously selected".to_owned()})?;
-		let (onion_payloads, htlc_msat, htlc_cltv) = onion_utils::build_onion_payloads(path, total_value, recipient_onion, cur_height, keysend_preimage)?;
-
-		let onion_packet = onion_utils::construct_onion_packet(onion_payloads, onion_keys, prng_seed, payment_hash)
-			.map_err(|_| APIError::InvalidRoute { err: "Route size too large considering onion data".to_owned()})?;
+		let (onion_packet, htlc_msat, htlc_cltv) = onion_utils::create_payment_onion(
+			&self.secp_ctx, &path, &session_priv, total_value, recipient_onion, cur_height,
+			payment_hash, keysend_preimage, prng_seed
+		)?;
 
 		let err: Result<(), _> = loop {
 			let (counterparty_node_id, id) = match self.short_to_chan_info.read().unwrap().get(&path.hops.first().unwrap().short_channel_id) {

lightning/src/ln/msgs.rs

@@ -1674,20 +1674,20 @@ pub use self::fuzzy_internal_msgs::*;
 #[cfg(not(fuzzing))]
 pub(crate) use self::fuzzy_internal_msgs::*;
 
-/// Bolt04 OnionPacket including hop data for the next peer
+/// Bolt 4 onion packet including hop data for the next peer.
 #[derive(Clone)]
 pub struct OnionPacket {
-	/// Bolt 04 version number
+	/// Bolt 4 version number.
 	pub version: u8,
 	/// In order to ensure we always return an error on onion decode in compliance with [BOLT
 	/// #4](https://github.com/lightning/bolts/blob/master/04-onion-routing.md), we have to
 	/// deserialize `OnionPacket`s contained in [`UpdateAddHTLC`] messages even if the ephemeral
 	/// public key (here) is bogus, so we hold a [`Result`] instead of a [`PublicKey`] as we'd
 	/// like.
 	pub public_key: Result<PublicKey, secp256k1::Error>,
-	/// 1300 bytes encrypted payload for the next hop
+	/// 1300 bytes encrypted payload for the next hop.
 	pub hop_data: [u8; 20*65],
-	/// HMAC to verify the integrity of hop_data
+	/// HMAC to verify the integrity of hop_data.
 	pub hmac: [u8; 32],
 }
 

lightning/src/ln/onion_utils.rs

@@ -936,26 +936,23 @@ pub(crate) fn decode_next_payment_hop<NS: Deref>(
 }
 
 /// Build a payment onion, returning the first hop msat and cltv values as well.
-pub fn create_payment_onion<T>(
-	secp_ctx: &Secp256k1<T>, path: &Path, session_priv: &SecretKey, total_msat: u64, 
-	recipient_onion: RecipientOnionFields, best_block_height: u32, payment_hash: PaymentHash,
-	keysend_preimage: Option<PaymentPreimage>, prng_seed: [u8; 32]
-) -> Result<(u64, u32, msgs::OnionPacket), ()>
-where
-	T: secp256k1::Signing
-{
-	let onion_keys = construct_onion_keys(&secp_ctx, &path, &session_priv).map_err(|_| ())?;
+pub fn create_payment_onion<T: secp256k1::Signing>(
+	secp_ctx: &Secp256k1<T>, path: &Path, session_priv: &SecretKey, total_msat: u64,
+	recipient_onion: RecipientOnionFields, best_block_height: u32, payment_hash: &PaymentHash,
+	keysend_preimage: &Option<PaymentPreimage>, prng_seed: [u8; 32]
+) -> Result<(msgs::OnionPacket, u64, u32), APIError> {
+	let onion_keys = construct_onion_keys(&secp_ctx, &path, &session_priv)
+		.map_err(|_| APIError::InvalidRoute{
+			err: "Pubkey along hop was maliciously selected".to_owned()
+		})?;
 	let (onion_payloads, htlc_msat, htlc_cltv) = build_onion_payloads(
-		&path,
-		total_msat,
-		recipient_onion,
-		best_block_height + 1,
-		&keysend_preimage,
-	).map_err(|_| ())?;
-	let onion_packet = construct_onion_packet(
-		onion_payloads, onion_keys, prng_seed, &payment_hash
+		&path, total_msat, recipient_onion, best_block_height, keysend_preimage
 	)?;
-	Ok((htlc_msat, htlc_cltv, onion_packet))
+	let onion_packet = construct_onion_packet(onion_payloads, onion_keys, prng_seed, payment_hash)
+		.map_err(|_| APIError::InvalidRoute{
+			err: "Route size too large considering onion data".to_owned()
+		})?;
+	Ok((onion_packet, htlc_msat, htlc_cltv))
 }
 
 pub(crate) fn decode_next_untagged_hop<T, R: ReadableArgs<T>, N: NextPacketBytes>(shared_secret: [u8; 32], hop_data: &[u8], hmac_bytes: [u8; 32], read_args: T) -> Result<(R, Option<([u8; 32], N)>), OnionDecodeErr> {

lightning/src/onion_message/mod.rs

@@ -28,7 +28,6 @@ mod functional_tests;
 
 // Re-export structs so they can be imported with just the `onion_message::` module prefix.
 pub use self::messenger::{CustomOnionMessageHandler, DefaultMessageRouter, Destination, MessageRouter, OnionMessageContents, OnionMessagePath, OnionMessenger, PeeledOnion, PendingOnionMessage, SendError};
-pub use self::messenger::{create_onion_message, peel_onion_message};
 #[cfg(not(c_bindings))]
 pub use self::messenger::{SimpleArcOnionMessenger, SimpleRefOnionMessenger};
 pub use self::offers::{OffersMessage, OffersMessageHandler};