From f8a36e5af40a79b58395aa05ec8c242c9250b01c Mon Sep 17 00:00:00 2001
From: Valentine Wallace <vwallace@protonmail.com>
Date: Thu, 13 May 2021 15:38:31 -0400
Subject: [PATCH] Parse keysend TLV field in onion.

This doesn't yet use the field, but it will be used in upcoming commits.
---
 lightning/src/ln/channelmanager.rs |  2 +-
 lightning/src/ln/msgs.rs           | 21 +++++++++++++++------
 lightning/src/ln/onion_utils.rs    |  1 +
 3 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/lightning/src/ln/channelmanager.rs b/lightning/src/ln/channelmanager.rs
index e7b1ff487..52ac049ab 100644
--- a/lightning/src/ln/channelmanager.rs
+++ b/lightning/src/ln/channelmanager.rs
@@ -1436,7 +1436,7 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
 				let payment_data = match next_hop_data.format {
 					msgs::OnionHopDataFormat::Legacy { .. } => None,
 					msgs::OnionHopDataFormat::NonFinalNode { .. } => return_err!("Got non final data with an HMAC of 0", 0x4000 | 22, &[0;0]),
-					msgs::OnionHopDataFormat::FinalNode { payment_data } => payment_data,
+					msgs::OnionHopDataFormat::FinalNode { payment_data, .. } => payment_data,
 				};
 
 				if payment_data.is_none() {
diff --git a/lightning/src/ln/msgs.rs b/lightning/src/ln/msgs.rs
index a64bbc01c..c1404db2f 100644
--- a/lightning/src/ln/msgs.rs
+++ b/lightning/src/ln/msgs.rs
@@ -880,7 +880,7 @@ pub trait RoutingMessageHandler : MessageSendEventsProvider {
 
 mod fuzzy_internal_msgs {
 	use prelude::*;
-	use ln::PaymentSecret;
+	use ln::{PaymentPreimage, PaymentSecret};
 
 	// These types aren't intended to be pub, but are exposed for direct fuzzing (as we deserialize
 	// them from untrusted input):
@@ -901,6 +901,7 @@ mod fuzzy_internal_msgs {
 		},
 		FinalNode {
 			payment_data: Option<FinalOnionHopData>,
+			keysend_preimage: Option<PaymentPreimage>
 		},
 	}
 
@@ -1300,14 +1301,15 @@ impl Writeable for OnionHopData {
 					(6, short_channel_id, required)
 				});
 			},
-			OnionHopDataFormat::FinalNode { ref payment_data } => {
+			OnionHopDataFormat::FinalNode { ref payment_data, ref keysend_preimage } => {
 				if let Some(final_data) = payment_data {
 					if final_data.total_msat > MAX_VALUE_MSAT { panic!("We should never be sending infinite/overflow onion payments"); }
 				}
 				encode_varint_length_prefixed_tlv!(w, {
 					(2, HighZeroBytesDroppedVarInt(self.amt_to_forward), required),
 					(4, HighZeroBytesDroppedVarInt(self.outgoing_cltv_value), required),
-					(8, payment_data, option)
+					(8, payment_data, option),
+					(5482373484, keysend_preimage, option)
 				});
 			},
 		}
@@ -1330,11 +1332,14 @@ impl Readable for OnionHopData {
 			let mut cltv_value = HighZeroBytesDroppedVarInt(0u32);
 			let mut short_id: Option<u64> = None;
 			let mut payment_data: Option<FinalOnionHopData> = None;
+			let mut keysend_preimage: Option<PaymentPreimage> = None;
+			// The TLV type is chosen to be compatible with lnd and c-lightning.
 			decode_tlv_stream!(&mut rd, {
 				(2, amt, required),
 				(4, cltv_value, required),
 				(6, short_id, option),
 				(8, payment_data, option),
+				(5482373484, keysend_preimage, option)
 			});
 			rd.eat_remaining().map_err(|_| DecodeError::ShortRead)?;
 			let format = if let Some(short_channel_id) = short_id {
@@ -1349,7 +1354,8 @@ impl Readable for OnionHopData {
 					}
 				}
 				OnionHopDataFormat::FinalNode {
-					payment_data
+					payment_data,
+					keysend_preimage,
 				}
 			};
 			(format, amt.0, cltv_value.0)
@@ -2529,6 +2535,7 @@ mod tests {
 		let mut msg = msgs::OnionHopData {
 			format: OnionHopDataFormat::FinalNode {
 				payment_data: None,
+				keysend_preimage: None,
 			},
 			amt_to_forward: 0x0badf00d01020304,
 			outgoing_cltv_value: 0xffffffff,
@@ -2537,7 +2544,7 @@ mod tests {
 		let target_value = hex::decode("1002080badf00d010203040404ffffffff").unwrap();
 		assert_eq!(encoded_value, target_value);
 		msg = Readable::read(&mut Cursor::new(&target_value[..])).unwrap();
-		if let OnionHopDataFormat::FinalNode { payment_data: None } = msg.format { } else { panic!(); }
+		if let OnionHopDataFormat::FinalNode { payment_data: None, .. } = msg.format { } else { panic!(); }
 		assert_eq!(msg.amt_to_forward, 0x0badf00d01020304);
 		assert_eq!(msg.outgoing_cltv_value, 0xffffffff);
 	}
@@ -2551,6 +2558,7 @@ mod tests {
 					payment_secret: expected_payment_secret,
 					total_msat: 0x1badca1f
 				}),
+				keysend_preimage: None,
 			},
 			amt_to_forward: 0x0badf00d01020304,
 			outgoing_cltv_value: 0xffffffff,
@@ -2563,7 +2571,8 @@ mod tests {
 			payment_data: Some(FinalOnionHopData {
 				payment_secret,
 				total_msat: 0x1badca1f
-			})
+			}),
+			keysend_preimage: None,
 		} = msg.format {
 			assert_eq!(payment_secret, expected_payment_secret);
 		} else { panic!(); }
diff --git a/lightning/src/ln/onion_utils.rs b/lightning/src/ln/onion_utils.rs
index 0deb8b74f..bd739d86e 100644
--- a/lightning/src/ln/onion_utils.rs
+++ b/lightning/src/ln/onion_utils.rs
@@ -141,6 +141,7 @@ pub(super) fn build_onion_payloads(path: &Vec<RouteHop>, total_msat: u64, paymen
 								total_msat,
 							})
 						} else { None },
+						keysend_preimage: None,
 					}
 				} else {
 					msgs::OnionHopDataFormat::NonFinalNode {
-- 
2.39.5