Support including invreqs when building payment onions

Add a new invoice request parameter to onion_utils::create_payment_onion. As of
this commit it will always be passed in as None, to be updated in future
commits.

Per <lightning/bolts#1149>, when paying a static
invoice we need to include our original invoice request in the HTLC onion since
the recipient wouldn't have received it previously.

Author: valentinewallace

lightning/src/ln/blinded_payment_tests.rs

@@ -1447,7 +1447,7 @@ fn route_blinding_spec_test_vector() {
 		}),
 	};
 	let cur_height = 747_000;
-	let (bob_onion, _, _) = onion_utils::create_payment_onion(&secp_ctx, &path, &session_priv, amt_msat, &RecipientOnionFields::spontaneous_empty(), cur_height, &PaymentHash([0; 32]), &None, [0; 32]).unwrap();
+	let (bob_onion, _, _) = onion_utils::create_payment_onion(&secp_ctx, &path, &session_priv, amt_msat, &RecipientOnionFields::spontaneous_empty(), cur_height, &PaymentHash([0; 32]), &None, None, [0; 32]).unwrap();
 
 	struct TestEcdhSigner {
 		node_secret: SecretKey,

lightning/src/ln/channelmanager.rs

@@ -4188,7 +4188,7 @@ where
 
 		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
+			payment_hash, keysend_preimage, None, prng_seed
 		).map_err(|e| {
 			let logger = WithContext::from(&self.logger, Some(path.hops.first().unwrap().pubkey), None, Some(*payment_hash));
 			log_error!(logger, "Failed to build an onion for path for payment hash {}", payment_hash);

lightning/src/ln/max_payment_path_len_tests.rs

@@ -110,7 +110,7 @@ fn large_payment_metadata() {
 	let secp_ctx = Secp256k1::signing_only();
 	route_0_1.paths[0].hops[0].fee_msat = MIN_FINAL_VALUE_ESTIMATE_WITH_OVERPAY;
 	route_0_1.paths[0].hops[0].cltv_expiry_delta = DEFAULT_MAX_TOTAL_CLTV_EXPIRY_DELTA;
-	let err = onion_utils::create_payment_onion(&secp_ctx, &route_0_1.paths[0], &test_utils::privkey(42), MIN_FINAL_VALUE_ESTIMATE_WITH_OVERPAY, &recipient_onion_too_large_md, nodes[0].best_block_info().1 + DEFAULT_MAX_TOTAL_CLTV_EXPIRY_DELTA, &payment_hash, &None, [0; 32]).unwrap_err();
+	let err = onion_utils::create_payment_onion(&secp_ctx, &route_0_1.paths[0], &test_utils::privkey(42), MIN_FINAL_VALUE_ESTIMATE_WITH_OVERPAY, &recipient_onion_too_large_md, nodes[0].best_block_info().1 + DEFAULT_MAX_TOTAL_CLTV_EXPIRY_DELTA, &payment_hash, &None, None, [0; 32]).unwrap_err();
 	match err {
 		APIError::InvalidRoute { err } => {
 			assert_eq!(err, "Route size too large considering onion data");
@@ -318,7 +318,7 @@ fn blinded_path_with_custom_tlv() {
 	let secp_ctx = Secp256k1::signing_only();
 	route.paths[0].hops[0].fee_msat = MIN_FINAL_VALUE_ESTIMATE_WITH_OVERPAY;
 	route.paths[0].hops[0].cltv_expiry_delta = DEFAULT_MAX_TOTAL_CLTV_EXPIRY_DELTA;
-	let err = onion_utils::create_payment_onion(&secp_ctx, &route.paths[0], &test_utils::privkey(42), MIN_FINAL_VALUE_ESTIMATE_WITH_OVERPAY, &recipient_onion_too_large_custom_tlv, nodes[0].best_block_info().1 + DEFAULT_MAX_TOTAL_CLTV_EXPIRY_DELTA, &payment_hash, &None, [0; 32]).unwrap_err();
+	let err = onion_utils::create_payment_onion(&secp_ctx, &route.paths[0], &test_utils::privkey(42), MIN_FINAL_VALUE_ESTIMATE_WITH_OVERPAY, &recipient_onion_too_large_custom_tlv, nodes[0].best_block_info().1 + DEFAULT_MAX_TOTAL_CLTV_EXPIRY_DELTA, &payment_hash, &None, None, [0; 32]).unwrap_err();
 	match err {
 		APIError::InvalidRoute { err } => {
 			assert_eq!(err, "Route size too large considering onion data");

lightning/src/ln/onion_payment.rs

@@ -569,7 +569,7 @@ mod tests {
 
 		let (onion, amount_msat, cltv_expiry) = create_payment_onion(
 			&secp_ctx, &path, &session_priv, total_amt_msat, &recipient_onion,
-			cur_height, &payment_hash, &Some(preimage), prng_seed
+			cur_height, &payment_hash, &Some(preimage), None, prng_seed
 		).unwrap();
 
 		let msg = make_update_add_msg(amount_msat, cltv_expiry, payment_hash, onion);

lightning/src/ln/onion_utils.rs

@@ -1163,7 +1163,8 @@ where
 pub fn create_payment_onion<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>, prng_seed: [u8; 32],
+	keysend_preimage: &Option<PaymentPreimage>, invoice_request: Option<&InvoiceRequest>,
+	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() }
@@ -1174,7 +1175,7 @@ pub fn create_payment_onion<T: secp256k1::Signing>(
 		recipient_onion,
 		cur_block_height,
 		keysend_preimage,
-		None,
+		invoice_request,
 	)?;
 	let onion_packet = construct_onion_packet(onion_payloads, onion_keys, prng_seed, payment_hash)
 		.map_err(|_| APIError::InvalidRoute {

lightning/src/ln/payment_tests.rs

@@ -4271,7 +4271,7 @@ fn peel_payment_onion_custom_tlvs() {
 
 	let (onion_routing_packet, first_hop_msat, cltv_expiry) = onion_utils::create_payment_onion(
 		&secp_ctx, &route.paths[0], &session_priv, amt_msat, &recipient_onion,
-		nodes[0].best_block_info().1, &payment_hash, &Some(keysend_preimage), prng_seed
+		nodes[0].best_block_info().1, &payment_hash, &Some(keysend_preimage), None, prng_seed
 	).unwrap();
 
 	let update_add = msgs::UpdateAddHTLC {