Bubble up invreq from htlc onion to forwarding flow

As part of receiving an async payment, we need to verify the sender's original
invoice request. Therefore, add support for parsing the invreq contained in the
onion and storing it in PendingHTLCForwards to prepare for when we add this
verification in an upcoming commit. The invreq also needs to be bubbled up for
inclusion in the PaymentClaimable event's PaymentPurpose.

Author: valentinewallace

lightning/src/ln/channelmanager.rs

@@ -240,6 +240,8 @@ pub enum PendingHTLCRouting {
 		/// [`PaymentSecret`] and should verify it using our
 		/// [`NodeSigner::get_inbound_payment_key`].
 		has_recipient_created_payment_secret: bool,
+		/// The [`InvoiceRequest`] associated with the [`Offer`] corresponding to this payment.
+		invoice_request: Option<InvoiceRequest>,
 		/// The context of the payment included by the recipient in a blinded path, or `None` if a
 		/// blinded path was not used.
 		///
@@ -6011,7 +6013,7 @@ where
 								let blinded_failure = routing.blinded_failure();
 								let (
 									cltv_expiry, onion_payload, payment_data, payment_context, phantom_shared_secret,
-									mut onion_fields, has_recipient_created_payment_secret
+									mut onion_fields, has_recipient_created_payment_secret, _invoice_request_opt
 								) = match routing {
 									PendingHTLCRouting::Receive {
 										payment_data, payment_metadata, payment_context,
@@ -6023,12 +6025,12 @@ where
 												payment_metadata, custom_tlvs };
 										(incoming_cltv_expiry, OnionPayload::Invoice { _legacy_hop_data },
 											Some(payment_data), payment_context, phantom_shared_secret, onion_fields,
-											true)
+											true, None)
 									},
 									PendingHTLCRouting::ReceiveKeysend {
 										payment_data, payment_preimage, payment_metadata,
 										incoming_cltv_expiry, custom_tlvs, requires_blinded_error: _,
-										has_recipient_created_payment_secret, payment_context,
+										has_recipient_created_payment_secret, payment_context, invoice_request,
 									} => {
 										let onion_fields = RecipientOnionFields {
 											payment_secret: payment_data.as_ref().map(|data| data.payment_secret),
@@ -6037,7 +6039,7 @@ where
 										};
 										(incoming_cltv_expiry, OnionPayload::Spontaneous(payment_preimage),
 											payment_data, payment_context, None, onion_fields,
-											has_recipient_created_payment_secret)
+											has_recipient_created_payment_secret, invoice_request)
 									},
 									_ => {
 										panic!("short_channel_id == 0 should imply any pending_forward entries are of type Receive");
@@ -12429,6 +12431,7 @@ impl_writeable_tlv_based_enum!(PendingHTLCRouting,
 		(5, custom_tlvs, optional_vec),
 		(7, has_recipient_created_payment_secret, (default_value, false)),
 		(9, payment_context, option),
+		(11, invoice_request, option),
 	},
 );
 

lightning/src/ln/msgs.rs

@@ -37,6 +37,7 @@ use crate::ln::types::ChannelId;
 use crate::types::payment::{PaymentPreimage, PaymentHash, PaymentSecret};
 use crate::types::features::{ChannelFeatures, ChannelTypeFeatures, InitFeatures, NodeFeatures};
 use crate::ln::onion_utils;
+use crate::offers::invoice_request::InvoiceRequest;
 use crate::onion_message;
 use crate::sign::{NodeSigner, Recipient};
 
@@ -1791,6 +1792,7 @@ mod fuzzy_internal_msgs {
 			payment_context: PaymentContext,
 			intro_node_blinding_point: Option<PublicKey>,
 			keysend_preimage: Option<PaymentPreimage>,
+			invoice_request: Option<InvoiceRequest>,
 			custom_tlvs: Vec<(u64, Vec<u8>)>,
 		}
 	}
@@ -2852,6 +2854,7 @@ impl<NS: Deref> ReadableArgs<(Option<PublicKey>, NS)> for InboundOnionPayload wh
 		let mut payment_metadata: Option<WithoutLength<Vec<u8>>> = None;
 		let mut total_msat = None;
 		let mut keysend_preimage: Option<PaymentPreimage> = None;
+		let mut invoice_request: Option<InvoiceRequest> = None;
 		let mut custom_tlvs = Vec::new();
 
 		let tlv_len = BigSize::read(r)?;
@@ -2865,6 +2868,7 @@ impl<NS: Deref> ReadableArgs<(Option<PublicKey>, NS)> for InboundOnionPayload wh
 			(12, intro_node_blinding_point, option),
 			(16, payment_metadata, option),
 			(18, total_msat, (option, encoding: (u64, HighZeroBytesDroppedBigSize))),
+			(77_777, invoice_request, option),
 			// See https://github.com/lightning/blips/blob/master/blip-0003.md
 			(5482373484, keysend_preimage, option)
 		}, |msg_type: u64, msg_reader: &mut FixedLengthReader<_>| -> Result<bool, DecodeError> {
@@ -2895,7 +2899,7 @@ impl<NS: Deref> ReadableArgs<(Option<PublicKey>, NS)> for InboundOnionPayload wh
 					short_channel_id, payment_relay, payment_constraints, features, next_blinding_override
 				})} => {
 					if amt.is_some() || cltv_value.is_some() || total_msat.is_some() ||
-						keysend_preimage.is_some()
+						keysend_preimage.is_some() || invoice_request.is_some()
 					{
 						return Err(DecodeError::InvalidValue)
 					}
@@ -2928,21 +2932,22 @@ impl<NS: Deref> ReadableArgs<(Option<PublicKey>, NS)> for InboundOnionPayload wh
 						payment_context,
 						intro_node_blinding_point,
 						keysend_preimage,
+						invoice_request,
 						custom_tlvs,
 					})
 				},
 			}
 		} else if let Some(short_channel_id) = short_id {
 			if payment_data.is_some() || payment_metadata.is_some() || encrypted_tlvs_opt.is_some() ||
-				total_msat.is_some()
+				total_msat.is_some() || invoice_request.is_some()
 			{ return Err(DecodeError::InvalidValue) }
 			Ok(Self::Forward {
 				short_channel_id,
 				amt_to_forward: amt.ok_or(DecodeError::InvalidValue)?,
 				outgoing_cltv_value: cltv_value.ok_or(DecodeError::InvalidValue)?,
 			})
 		} else {
-			if encrypted_tlvs_opt.is_some() || total_msat.is_some() {
+			if encrypted_tlvs_opt.is_some() || total_msat.is_some() || invoice_request.is_some() {
 				return Err(DecodeError::InvalidValue)
 			}
 			if let Some(data) = &payment_data {

lightning/src/ln/onion_payment.rs

@@ -135,18 +135,19 @@ pub(super) fn create_recv_pending_htlc_info(
 ) -> Result<PendingHTLCInfo, InboundHTLCErr> {
 	let (
 		payment_data, keysend_preimage, custom_tlvs, onion_amt_msat, onion_cltv_expiry,
-		payment_metadata, payment_context, requires_blinded_error, has_recipient_created_payment_secret
+		payment_metadata, payment_context, requires_blinded_error, has_recipient_created_payment_secret,
+		invoice_request
 	) = match hop_data {
 		msgs::InboundOnionPayload::Receive {
 			payment_data, keysend_preimage, custom_tlvs, sender_intended_htlc_amt_msat,
 			cltv_expiry_height, payment_metadata, ..
 		} =>
 			(payment_data, keysend_preimage, custom_tlvs, sender_intended_htlc_amt_msat,
-			 cltv_expiry_height, payment_metadata, None, false, keysend_preimage.is_none()),
+			 cltv_expiry_height, payment_metadata, None, false, keysend_preimage.is_none(), None),
 		msgs::InboundOnionPayload::BlindedReceive {
 			sender_intended_htlc_amt_msat, total_msat, cltv_expiry_height, payment_secret,
 			intro_node_blinding_point, payment_constraints, payment_context, keysend_preimage,
-			custom_tlvs
+			custom_tlvs, invoice_request
 		} => {
 			check_blinded_payment_constraints(
 				sender_intended_htlc_amt_msat, cltv_expiry, &payment_constraints
@@ -161,7 +162,7 @@ pub(super) fn create_recv_pending_htlc_info(
 			let payment_data = msgs::FinalOnionHopData { payment_secret, total_msat };
 			(Some(payment_data), keysend_preimage, custom_tlvs,
 			 sender_intended_htlc_amt_msat, cltv_expiry_height, None, Some(payment_context),
-			 intro_node_blinding_point.is_none(), true)
+			 intro_node_blinding_point.is_none(), true, invoice_request)
 		}
 		msgs::InboundOnionPayload::Forward { .. } => {
 			return Err(InboundHTLCErr {
@@ -236,6 +237,7 @@ pub(super) fn create_recv_pending_htlc_info(
 			requires_blinded_error,
 			has_recipient_created_payment_secret,
 			payment_context,
+			invoice_request,
 		}
 	} else if let Some(data) = payment_data {
 		PendingHTLCRouting::Receive {