Make attribution_data optional

we need this for deserializing various old objects, eg if we decided
to fail an htlc on a previous version, stored that that htlc is
pending-failure and then shut down and upgraded.

Author: TheBlueMatt

lightning/src/ln/channel.rs

@@ -4672,7 +4672,7 @@ trait FailHTLCContents {
 impl FailHTLCContents for msgs::OnionErrorPacket {
 	type Message = msgs::UpdateFailHTLC;
 	fn to_message(self, htlc_id: u64, channel_id: ChannelId) -> Self::Message {
-		msgs::UpdateFailHTLC { htlc_id, channel_id, reason: self.data, attribution_data: Some(self.attribution_data) }
+		msgs::UpdateFailHTLC { htlc_id, channel_id, reason: self.data, attribution_data: self.attribution_data }
 	}
 	fn to_inbound_htlc_state(self) -> InboundHTLCState {
 		InboundHTLCState::LocalRemoved(InboundHTLCRemovalReason::FailRelay(self))
@@ -6700,7 +6700,7 @@ impl<SP: Deref> FundedChannel<SP> where
 							channel_id: self.context.channel_id(),
 							htlc_id: htlc.htlc_id,
 							reason: err_packet.data.clone(),
-							attribution_data: Some(err_packet.attribution_data)
+							attribution_data: err_packet.attribution_data,
 						});
 					},
 					&InboundHTLCRemovalReason::FailMalformed((ref sha256_of_onion, ref failure_code)) => {

lightning/src/ln/channelmanager.rs

@@ -4417,7 +4417,7 @@ where
 			channel_id: msg.channel_id,
 			htlc_id: msg.htlc_id,
 			reason: failure.data.clone(),
-			attribution_data: Some(failure.attribution_data)
+			attribution_data: failure.attribution_data,
 		})
 	}
 
@@ -4448,7 +4448,7 @@ where
 						channel_id: msg.channel_id,
 						htlc_id: msg.htlc_id,
 						reason: failure.data,
-						attribution_data: Some(failure.attribution_data)
+						attribution_data: failure.attribution_data,
 					}));
 				}
 			}

lightning/src/ln/msgs.rs

@@ -2039,14 +2039,14 @@ pub(crate) struct OnionErrorPacket {
 	// This really should be a constant size slice, but the spec lets these things be up to 128KB?
 	// (TODO) We limit it in decode to much lower...
 	pub(crate) data: Vec<u8>,
-	pub(crate) attribution_data: [u8; ATTRIBUTION_DATA_LEN]
+	pub(crate) attribution_data: Option<[u8; ATTRIBUTION_DATA_LEN]>,
 }
 
 impl From<&UpdateFailHTLC> for OnionErrorPacket {
 	fn from(msg: &UpdateFailHTLC) -> Self {
 		OnionErrorPacket {
 			data: msg.reason.clone(),
-			attribution_data: msg.attribution_data.unwrap(),	// TODO: Make safe
+			attribution_data: msg.attribution_data,
 		}
 	}
 }

lightning/src/ln/onion_payment.rs

@@ -406,7 +406,7 @@ where
 			channel_id: msg.channel_id,
 			htlc_id: msg.htlc_id,
 			reason: failure.data,
-			attribution_data: Some(failure.attribution_data)
+			attribution_data: failure.attribution_data,
 		}));
 	};
 

lightning/src/ln/onion_utils.rs

@@ -929,7 +929,7 @@ pub(super) fn build_failure_packet(
 
 	OnionErrorPacket {
 		data: data,
-		attribution_data,
+		attribution_data: Some(attribution_data),
 	}
 }
 
@@ -1077,8 +1077,8 @@ where
 		// Check attr error hmacs
 
 		let message = &encrypted_packet.data;
-		let payloads = &encrypted_packet.attribution_data[..MAX_HOPS * PAYLOAD_LEN];
-		let hmacs = &encrypted_packet.attribution_data[MAX_HOPS * PAYLOAD_LEN..];
+		let payloads = &encrypted_packet.attribution_data.as_ref().unwrap()[..MAX_HOPS * PAYLOAD_LEN]; // XXX: This will break if we get an err from an unupgraded node
+		let hmacs = &encrypted_packet.attribution_data.as_ref().unwrap()[MAX_HOPS * PAYLOAD_LEN..]; // XXX: This will break if we get an err from an unupgraded node
 
 		let um = gen_um_from_shared_secret(shared_secret.as_ref());
 		let mut hmac = HmacEngine::<Sha256>::new(&um);
@@ -1108,11 +1108,11 @@ where
 		}
 
 		// Shift payloads left.
-		let payloads = &mut encrypted_packet.attribution_data[..MAX_HOPS * PAYLOAD_LEN];
+		let payloads = &mut encrypted_packet.attribution_data.as_mut().unwrap()[..MAX_HOPS * PAYLOAD_LEN]; // XXX: This will break if we get an err from an unupgraded node
 		payloads.copy_within(PAYLOAD_LEN.., 0);
 
 		// Shift hmacs left.
-		let hmacs = &mut encrypted_packet.attribution_data[MAX_HOPS * PAYLOAD_LEN..];
+		let hmacs = &mut encrypted_packet.attribution_data.as_mut().unwrap()[MAX_HOPS * PAYLOAD_LEN..]; // XXX: This will break if we get an err from an unupgraded node
 		let mut src_idx = MAX_HOPS;
 		let mut dest_idx = 1;
 		let mut copy_len = MAX_HOPS - 1;
@@ -1428,7 +1428,7 @@ impl HTLCFailReason {
 	}
 
 	pub(super) fn from_msg(msg: &msgs::UpdateFailHTLC) -> Self {
-		Self(HTLCFailReasonRepr::LightningError { err: OnionErrorPacket{ data: msg.reason.clone(), attribution_data: msg.attribution_data.unwrap() } }) // TODO: Make safe
+		Self(HTLCFailReasonRepr::LightningError { err: OnionErrorPacket{ data: msg.reason.clone(), attribution_data: msg.attribution_data } })
 	}
 
 	pub(super) fn get_encrypted_failure_packet(
@@ -1922,7 +1922,7 @@ fn process_failure_packet(onion_error: &mut OnionErrorPacket, shared_secret: &[u
 
 	// Shift payloads right.
 	{
-		let payloads = &onion_error.attribution_data[..MAX_HOPS * PAYLOAD_LEN];
+		let payloads = &onion_error.attribution_data.as_ref().unwrap()[..MAX_HOPS * PAYLOAD_LEN]; // XXX: This will break if we get an err from an unupgraded node
 		processed_packet[PAYLOAD_LEN..MAX_HOPS * PAYLOAD_LEN].copy_from_slice(&payloads[..payloads.len()-PAYLOAD_LEN]);
 
 		// Add this node's payload.
@@ -1931,7 +1931,7 @@ fn process_failure_packet(onion_error: &mut OnionErrorPacket, shared_secret: &[u
 
 	// Shift hmacs right.
 	{
-		let hmacs = &onion_error.attribution_data[MAX_HOPS * PAYLOAD_LEN..];
+		let hmacs = &onion_error.attribution_data.as_ref().unwrap()[MAX_HOPS * PAYLOAD_LEN..]; // XXX: This will break if we get an err from an unupgraded node
 		let processed_hmacs = &mut processed_packet[MAX_HOPS * PAYLOAD_LEN..];
 
 		let mut src_idx = HMAC_COUNT - 2;
@@ -1956,7 +1956,7 @@ fn process_failure_packet(onion_error: &mut OnionErrorPacket, shared_secret: &[u
 	// Add this node's hmacs.
 	add_hmacs(&shared_secret, &onion_error.data, &mut processed_packet);
 
-	onion_error.attribution_data = processed_packet;
+	onion_error.attribution_data = Some(processed_packet);
 }