Add MppId field to HTLCSource as a way to correlate mpp payment paths

Author: valentinewallace

lightning/src/ln/channel.rs

@@ -5525,7 +5525,7 @@ mod tests {
 	use bitcoin::hashes::hex::FromHex;
 	use hex;
 	use ln::{PaymentPreimage, PaymentHash};
-	use ln::channelmanager::HTLCSource;
+	use ln::channelmanager::{HTLCSource, MppId};
 	use ln::channel::{Channel,InboundHTLCOutput,OutboundHTLCOutput,InboundHTLCState,OutboundHTLCState,HTLCOutputInCommitment,HTLCCandidate,HTLCInitiator,TxCreationKeys};
 	use ln::channel::MAX_FUNDING_SATOSHIS;
 	use ln::features::InitFeatures;
@@ -5699,6 +5699,7 @@ mod tests {
 				path: Vec::new(),
 				session_priv: SecretKey::from_slice(&hex::decode("0fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff").unwrap()[..]).unwrap(),
 				first_hop_htlc_msat: 548,
+				mpp_id: MppId([42; 32]),
 			}
 		});
 

lightning/src/ln/channelmanager.rs

@@ -173,6 +173,22 @@ struct ClaimableHTLC {
 	onion_payload: OnionPayload,
 }
 
+/// A payment identifier used to correlate an MPP payment's per-path HTLC sources internally.
+#[derive(Hash, Copy, Clone, PartialEq, Eq, Debug)]
+pub(crate) struct MppId(pub [u8; 32]);
+
+impl Writeable for MppId {
+	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
+		self.0.write(w)
+	}
+}
+
+impl Readable for MppId {
+	fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
+		let buf: [u8; 32] = Readable::read(r)?;
+		Ok(MppId(buf))
+	}
+}
 /// Tracks the inbound corresponding to an outbound HTLC
 #[derive(Clone, PartialEq)]
 pub(crate) enum HTLCSource {
@@ -183,6 +199,7 @@ pub(crate) enum HTLCSource {
 		/// Technically we can recalculate this from the route, but we cache it here to avoid
 		/// doing a double-pass on route when we get a failure back
 		first_hop_htlc_msat: u64,
+		mpp_id: MppId,
 	},
 }
 #[cfg(test)]
@@ -192,6 +209,7 @@ impl HTLCSource {
 			path: Vec::new(),
 			session_priv: SecretKey::from_slice(&[1; 32]).unwrap(),
 			first_hop_htlc_msat: 0,
+			mpp_id: MppId([2; 32]),
 		}
 	}
 }
@@ -1820,7 +1838,7 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
 	}
 
 	// Only public for testing, this should otherwise never be called direcly
-	pub(crate) fn send_payment_along_path(&self, path: &Vec<RouteHop>, payment_hash: &PaymentHash, payment_secret: &Option<PaymentSecret>, total_value: u64, cur_height: u32, keysend_preimage: &Option<PaymentPreimage>) -> Result<(), APIError> {
+	pub(crate) fn send_payment_along_path(&self, path: &Vec<RouteHop>, payment_hash: &PaymentHash, payment_secret: &Option<PaymentSecret>, total_value: u64, cur_height: u32, mpp_id: MppId, keysend_preimage: &Option<PaymentPreimage>) -> Result<(), APIError> {
 		log_trace!(self.logger, "Attempting to send payment for path with next hop {}", path.first().unwrap().short_channel_id);
 		let prng_seed = self.keys_manager.get_secure_random_bytes();
 		let session_priv_bytes = self.keys_manager.get_secure_random_bytes();
@@ -1857,6 +1875,7 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
 						path: path.clone(),
 						session_priv: session_priv.clone(),
 						first_hop_htlc_msat: htlc_msat,
+						mpp_id,
 					}, onion_packet, &self.logger), channel_state, chan)
 				} {
 					Some((update_add, commitment_signed, monitor_update)) => {
@@ -1956,6 +1975,7 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
 		let mut total_value = 0;
 		let our_node_id = self.get_our_node_id();
 		let mut path_errs = Vec::with_capacity(route.paths.len());
+		let mpp_id = MppId(self.keys_manager.get_secure_random_bytes());
 		'path_check: for path in route.paths.iter() {
 			if path.len() < 1 || path.len() > 20 {
 				path_errs.push(Err(APIError::RouteError{err: "Path didn't go anywhere/had bogus size"}));
@@ -1977,7 +1997,7 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
 		let cur_height = self.best_block.read().unwrap().height() + 1;
 		let mut results = Vec::new();
 		for path in route.paths.iter() {
-			results.push(self.send_payment_along_path(&path, &payment_hash, payment_secret, total_value, cur_height, &keysend_preimage));
+			results.push(self.send_payment_along_path(&path, &payment_hash, payment_secret, total_value, cur_height, mpp_id, &keysend_preimage));
 		}
 		let mut has_ok = false;
 		let mut has_err = false;
@@ -4911,14 +4931,60 @@ impl Readable for ClaimableHTLC {
 	}
 }
 
-impl_writeable_tlv_based_enum!(HTLCSource,
-	(0, OutboundRoute) => {
-		(0, session_priv, required),
-		(2, first_hop_htlc_msat, required),
-		(4, path, vec_type),
-	}, ;
-	(1, PreviousHopData)
-);
+impl Readable for HTLCSource {
+	fn read<R: Read>(reader: &mut R) -> Result<Self, DecodeError> {
+		let id: u8 = Readable::read(reader)?;
+		match id {
+			0 => {
+				let mut session_priv: ::util::ser::OptionDeserWrapper<SecretKey> = ::util::ser::OptionDeserWrapper(None);
+				let mut first_hop_htlc_msat: u64 = 0;
+				let mut path = Some(Vec::new());
+				let mut mpp_id = None;
+				read_tlv_fields!(reader, {
+					(0, session_priv, required),
+					(1, mpp_id, option),
+					(2, first_hop_htlc_msat, required),
+					(4, path, vec_type),
+				});
+				if mpp_id.is_none() {
+					// For backwards compat, if there was no mpp_id written, use the session_priv bytes
+					// instead.
+					mpp_id = Some(MppId(*session_priv.0.unwrap().as_ref()));
+				}
+				Ok(HTLCSource::OutboundRoute {
+					session_priv: session_priv.0.unwrap(),
+					first_hop_htlc_msat: first_hop_htlc_msat,
+					path: path.unwrap(),
+					mpp_id: mpp_id.unwrap(),
+				})
+			}
+			1 => Ok(HTLCSource::PreviousHopData(Readable::read(reader)?)),
+			_ => Err(DecodeError::UnknownRequiredFeature),
+		}
+	}
+}
+
+impl Writeable for HTLCSource {
+	fn write<W: Writer>(&self, writer: &mut W) -> Result<(), ::io::Error> {
+		match self {
+			HTLCSource::OutboundRoute { ref session_priv, ref first_hop_htlc_msat, ref path, mpp_id } => {
+				0u8.write(writer)?;
+				let mpp_id_opt = Some(mpp_id);
+				write_tlv_fields!(writer, {
+					(0, session_priv, required),
+					(1, mpp_id_opt, option),
+					(2, first_hop_htlc_msat, required),
+					(4, path, vec_type),
+				 });
+			}
+			HTLCSource::PreviousHopData(ref field) => {
+				1u8.write(writer)?;
+				field.write(writer)?;
+			}
+		}
+		Ok(())
+	}
+}
 
 impl_writeable_tlv_based_enum!(HTLCFailReason,
 	(0, LightningError) => {
@@ -5364,7 +5430,7 @@ mod tests {
 	use bitcoin::hashes::sha256::Hash as Sha256;
 	use core::time::Duration;
 	use ln::{PaymentPreimage, PaymentHash, PaymentSecret};
-	use ln::channelmanager::PaymentSendFailure;
+	use ln::channelmanager::{MppId, PaymentSendFailure};
 	use ln::features::{InitFeatures, InvoiceFeatures};
 	use ln::functional_test_utils::*;
 	use ln::msgs;
@@ -5515,10 +5581,11 @@ mod tests {
 		let net_graph_msg_handler = &nodes[0].net_graph_msg_handler;
 		let route = get_route(&nodes[0].node.get_our_node_id(), &net_graph_msg_handler.network_graph, &nodes[1].node.get_our_node_id(), Some(InvoiceFeatures::known()), None, &Vec::new(), 100_000, TEST_FINAL_CLTV, &logger).unwrap();
 		let (payment_preimage, our_payment_hash, payment_secret) = get_payment_preimage_hash!(&nodes[1]);
+		let mpp_id = MppId([42; 32]);
 		// Use the utility function send_payment_along_path to send the payment with MPP data which
 		// indicates there are more HTLCs coming.
 		let cur_height = CHAN_CONFIRM_DEPTH + 1; // route_payment calls send_payment, which adds 1 to the current height. So we do the same here to match.
-		nodes[0].node.send_payment_along_path(&route.paths[0], &our_payment_hash, &Some(payment_secret), 200_000, cur_height, &None).unwrap();
+		nodes[0].node.send_payment_along_path(&route.paths[0], &our_payment_hash, &Some(payment_secret), 200_000, cur_height, mpp_id, &None).unwrap();
 		check_added_monitors!(nodes[0], 1);
 		let mut events = nodes[0].node.get_and_clear_pending_msg_events();
 		assert_eq!(events.len(), 1);
@@ -5548,7 +5615,7 @@ mod tests {
 		expect_payment_failed!(nodes[0], our_payment_hash, true);
 
 		// Send the second half of the original MPP payment.
-		nodes[0].node.send_payment_along_path(&route.paths[0], &our_payment_hash, &Some(payment_secret), 200_000, cur_height, &None).unwrap();
+		nodes[0].node.send_payment_along_path(&route.paths[0], &our_payment_hash, &Some(payment_secret), 200_000, cur_height, mpp_id, &None).unwrap();
 		check_added_monitors!(nodes[0], 1);
 		let mut events = nodes[0].node.get_and_clear_pending_msg_events();
 		assert_eq!(events.len(), 1);

lightning/src/ln/functional_tests.rs

@@ -19,7 +19,7 @@ use chain::transaction::OutPoint;
 use chain::keysinterface::BaseSign;
 use ln::{PaymentPreimage, PaymentSecret, PaymentHash};
 use ln::channel::{COMMITMENT_TX_BASE_WEIGHT, COMMITMENT_TX_WEIGHT_PER_HTLC};
-use ln::channelmanager::{ChannelManager, ChannelManagerReadArgs, RAACommitmentOrder, PaymentSendFailure, BREAKDOWN_TIMEOUT, MIN_CLTV_EXPIRY_DELTA};
+use ln::channelmanager::{ChannelManager, ChannelManagerReadArgs, MppId, RAACommitmentOrder, PaymentSendFailure, BREAKDOWN_TIMEOUT, MIN_CLTV_EXPIRY_DELTA};
 use ln::channel::{Channel, ChannelError};
 use ln::{chan_utils, onion_utils};
 use ln::chan_utils::HTLC_SUCCESS_TX_WEIGHT;
@@ -3886,7 +3886,8 @@ fn do_test_htlc_timeout(send_partial_mpp: bool) {
 		// Use the utility function send_payment_along_path to send the payment with MPP data which
 		// indicates there are more HTLCs coming.
 		let cur_height = CHAN_CONFIRM_DEPTH + 1; // route_payment calls send_payment, which adds 1 to the current height. So we do the same here to match.
-		nodes[0].node.send_payment_along_path(&route.paths[0], &our_payment_hash, &Some(payment_secret), 200000, cur_height, &None).unwrap();
+		let mpp_id = MppId([42; 32]);
+		nodes[0].node.send_payment_along_path(&route.paths[0], &our_payment_hash, &Some(payment_secret), 200000, cur_height, mpp_id, &None).unwrap();
 		check_added_monitors!(nodes[0], 1);
 		let mut events = nodes[0].node.get_and_clear_pending_msg_events();
 		assert_eq!(events.len(), 1);

lightning/src/ln/onion_utils.rs

@@ -332,7 +332,7 @@ pub(super) fn build_first_hop_failure_packet(shared_secret: &[u8], failure_type:
 /// Returns update, a boolean indicating that the payment itself failed, and the error code.
 #[inline]
 pub(super) fn process_onion_failure<T: secp256k1::Signing, L: Deref>(secp_ctx: &Secp256k1<T>, logger: &L, htlc_source: &HTLCSource, mut packet_decrypted: Vec<u8>) -> (Option<NetworkUpdate>, bool, Option<u16>, Option<Vec<u8>>) where L::Target: Logger {
-	if let &HTLCSource::OutboundRoute { ref path, ref session_priv, ref first_hop_htlc_msat } = htlc_source {
+	if let &HTLCSource::OutboundRoute { ref path, ref session_priv, ref first_hop_htlc_msat, .. } = htlc_source {
 		let mut res = None;
 		let mut htlc_msat = *first_hop_htlc_msat;
 		let mut error_code_ret = None;