f: use total_msat as err data when is multipath

Author: a-mpch

lightning/src/ln/onion_payment.rs

@@ -78,16 +78,20 @@ fn check_blinded_forward(
 fn check_trampoline_onion_constraints(
 	outer_hop_data: &msgs::InboundTrampolineEntrypointPayload, trampoline_cltv_value: u32,
 	trampoline_amount: u64,
-) -> Result<(), LocalHTLCFailureReason> {
+) -> Result<(), (LocalHTLCFailureReason, Vec<u8>)> {
 	if outer_hop_data.outgoing_cltv_value < trampoline_cltv_value {
-		return Err(LocalHTLCFailureReason::FinalIncorrectCLTVExpiry);
+		let mut err_data = Vec::new();
+		outer_hop_data.outgoing_cltv_value.write(&mut err_data).unwrap();
+		return Err((LocalHTLCFailureReason::FinalIncorrectCLTVExpiry, err_data));
 	}
 	let outgoing_amount = outer_hop_data
 		.multipath_trampoline_data
 		.as_ref()
 		.map_or(outer_hop_data.amt_to_forward, |mtd| mtd.total_msat);
 	if outgoing_amount < trampoline_amount {
-		return Err(LocalHTLCFailureReason::FinalIncorrectHTLCAmount);
+		let mut err_data = Vec::new();
+		outgoing_amount.write(&mut err_data).unwrap();
+		return Err((LocalHTLCFailureReason::FinalIncorrectHTLCAmount, err_data));
 	}
 
 	Ok(())
@@ -155,17 +159,8 @@ pub(super) fn create_fwd_pending_htlc_info(
 				err_data: Vec::new(),
 			}),
 		onion_utils::Hop::TrampolineForward { ref outer_hop_data, next_trampoline_hop_data, next_trampoline_hop_hmac, new_trampoline_packet_bytes, trampoline_shared_secret, .. } => {
-			check_trampoline_onion_constraints(outer_hop_data, next_trampoline_hop_data.outgoing_cltv_value, next_trampoline_hop_data.amt_to_forward).map_err(|reason| {
-				let mut err_data = Vec::new();
-				match reason {
-					LocalHTLCFailureReason::FinalIncorrectCLTVExpiry => {
-						outer_hop_data.outgoing_cltv_value.write(&mut err_data).unwrap();
-					}
-					LocalHTLCFailureReason::FinalIncorrectHTLCAmount => {
-						outer_hop_data.amt_to_forward.write(&mut err_data).unwrap();
-					}
-					_ => unreachable!()
-				}
+			check_trampoline_onion_constraints(outer_hop_data, next_trampoline_hop_data.outgoing_cltv_value, next_trampoline_hop_data.amt_to_forward).map_err(|(reason, err_data)| {
+				//TODO: return reason as forward issue, not as receiving issue.
 				// The Trampoline onion's amt and CLTV values cannot exceed the outer onion's
 				InboundHTLCErr {
 					reason,
@@ -333,17 +328,7 @@ pub(super) fn create_recv_pending_htlc_info(
 				cltv_expiry_height, payment_metadata, ..
 			}, ..
 		} => {
-			check_trampoline_onion_constraints(outer_hop_data, cltv_expiry_height, sender_intended_htlc_amt_msat).map_err(|reason| {
-				let mut err_data = Vec::new();
-				match reason {
-					LocalHTLCFailureReason::FinalIncorrectCLTVExpiry => {
-						outer_hop_data.outgoing_cltv_value.write(&mut err_data).unwrap();
-					}
-					LocalHTLCFailureReason::FinalIncorrectHTLCAmount => {
-						outer_hop_data.amt_to_forward.write(&mut err_data).unwrap();
-					}
-					_ => unreachable!()
-				}
+			check_trampoline_onion_constraints(outer_hop_data, cltv_expiry_height, sender_intended_htlc_amt_msat).map_err(|(reason, err_data)| {
 				// The Trampoline onion's amt and CLTV values cannot exceed the outer onion's
 				InboundHTLCErr {
 					reason,