Support encoding invreqs in outbound onion payloads.

Author: valentinewallace

lightning/src/ln/max_payment_path_len_tests.rs

@@ -184,6 +184,7 @@ fn one_hop_blinded_path_with_custom_tlv() {
 		encrypted_tlvs: &blinded_path.blinded_hops()[0].encrypted_payload,
 		intro_node_blinding_point: Some(blinded_path.blinding_point()),
 		keysend_preimage: None,
+		invoice_request: None,
 		custom_tlvs: &Vec::new()
 	}.serialized_length();
 	let max_custom_tlv_len = 1300

lightning/src/ln/msgs.rs

@@ -1749,6 +1749,7 @@ mod fuzzy_internal_msgs {
 	use crate::blinded_path::payment::{PaymentConstraints, PaymentContext, PaymentRelay};
 	use crate::ln::types::{PaymentPreimage, PaymentSecret};
 	use crate::ln::features::BlindedHopFeatures;
+	use crate::offers::invoice_request::InvoiceRequest;
 	use super::{FinalOnionHopData, TrampolineOnionPacket};
 
 	#[allow(unused_imports)]
@@ -1827,6 +1828,7 @@ mod fuzzy_internal_msgs {
 			intro_node_blinding_point: Option<PublicKey>, // Set if the introduction node of the blinded path is the final node
 			keysend_preimage: Option<PaymentPreimage>,
 			custom_tlvs: &'a Vec<(u64, Vec<u8>)>,
+			invoice_request: Option<&'a InvoiceRequest>,
 		}
 	}
 
@@ -2687,6 +2689,9 @@ impl Readable for FinalOnionHopData {
 	}
 }
 
+// This TLV type isn't stabilized in the BOLTs.
+const ONION_INVREQ_TLV_TYPE: u64 = 77_777;
+
 impl<'a> Writeable for OutboundOnionPayload<'a> {
 	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 		match self {
@@ -2733,13 +2738,17 @@ impl<'a> Writeable for OutboundOnionPayload<'a> {
 			},
 			Self::BlindedReceive {
 				sender_intended_htlc_amt_msat, total_msat, cltv_expiry_height, encrypted_tlvs,
-				intro_node_blinding_point, keysend_preimage, ref custom_tlvs,
+				intro_node_blinding_point, keysend_preimage, ref invoice_request, ref custom_tlvs,
 			} => {
 				// We need to update [`ln::outbound_payment::RecipientOnionFields::with_custom_tlvs`]
 				// to reject any reserved types in the experimental range if new ones are ever
 				// standardized.
+				let invoice_request_tlv = invoice_request.map(|invreq| (ONION_INVREQ_TLV_TYPE, invreq.encode()));
 				let keysend_tlv = keysend_preimage.map(|preimage| (5482373484, preimage.encode()));
-				let mut custom_tlvs: Vec<&(u64, Vec<u8>)> = custom_tlvs.iter().chain(keysend_tlv.iter()).collect();
+				let mut custom_tlvs: Vec<&(u64, Vec<u8>)> = custom_tlvs.iter()
+					.chain(invoice_request_tlv.iter())
+					.chain(keysend_tlv.iter())
+					.collect();
 				custom_tlvs.sort_unstable_by_key(|(typ, _)| *typ);
 				_encode_varint_length_prefixed_tlv!(w, {
 					(2, HighZeroBytesDroppedBigSize(*sender_intended_htlc_amt_msat), required),

lightning/src/ln/onion_utils.rs

@@ -262,6 +262,7 @@ where
 								encrypted_tlvs: &blinded_hop.encrypted_payload,
 								intro_node_blinding_point: blinding_point.take(),
 								keysend_preimage: *keysend_preimage,
+								invoice_request: None,
 								custom_tlvs: &recipient_onion.custom_tlvs,
 							},
 						);