Implement sending keysend payments (to public nodes)

Author: valentinewallace

lightning/src/ln/channelmanager.rs

@@ -1718,15 +1718,15 @@ 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) -> 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, 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();
 		let session_priv = SecretKey::from_slice(&session_priv_bytes[..]).expect("RNG is busted");
 
 		let onion_keys = onion_utils::construct_onion_keys(&self.secp_ctx, &path, &session_priv)
 			.map_err(|_| APIError::RouteError{err: "Pubkey along hop was maliciously selected"})?;
-		let (onion_payloads, htlc_msat, htlc_cltv) = onion_utils::build_onion_payloads(path, total_value, payment_secret, cur_height)?;
+		let (onion_payloads, htlc_msat, htlc_cltv) = onion_utils::build_onion_payloads(path, total_value, payment_secret, cur_height, keysend_preimage)?;
 		if onion_utils::route_size_insane(&onion_payloads) {
 			return Err(APIError::RouteError{err: "Route size too large considering onion data"});
 		}
@@ -1835,6 +1835,10 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
 	/// bit set (either as required or as available). If multiple paths are present in the Route,
 	/// we assume the invoice had the basic_mpp feature set.
 	pub fn send_payment(&self, route: &Route, payment_hash: PaymentHash, payment_secret: &Option<PaymentSecret>) -> Result<(), PaymentSendFailure> {
+		self.send_payment_internal(route, payment_hash, payment_secret, None)
+	}
+
+	fn send_payment_internal(&self, route: &Route, payment_hash: PaymentHash, payment_secret: &Option<PaymentSecret>, keysend_preimage: Option<PaymentPreimage>) -> Result<(), PaymentSendFailure> {
 		if route.paths.len() < 1 {
 			return Err(PaymentSendFailure::ParameterError(APIError::RouteError{err: "There must be at least one path to send over"}));
 		}
@@ -1868,7 +1872,7 @@ 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));
+			results.push(self.send_payment_along_path(&path, &payment_hash, payment_secret, total_value, cur_height, &keysend_preimage));
 		}
 		let mut has_ok = false;
 		let mut has_err = false;
@@ -1892,6 +1896,28 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
 		}
 	}
 
+	/// Send a spontaneous payment, which is a payment that does not require the recipient to have
+	/// generated an invoice. Optionally, you may specify the preimage. If you do choose to specify
+	/// the preimage, it must be a cryptographically secure random value that no intermediate node
+	/// would be able to guess -- otherwise, an intermediate node may claim the payment and it will
+	/// never reach the recipient.
+	///
+	/// Similar to regular payments, you MUST NOT reuse a `payment_preimage` value. See
+	/// [`send_payment`] for more information about the risks of duplicate preimage usage.
+	///
+	/// [`send_payment`]: Self::send_payment
+	pub fn send_spontaneous_payment(&self, route: &Route, payment_preimage: Option<PaymentPreimage>) -> Result<PaymentHash, PaymentSendFailure> {
+		let preimage = match payment_preimage {
+			Some(p) => p,
+			None => PaymentPreimage(self.keys_manager.get_secure_random_bytes()),
+		};
+		let payment_hash = PaymentHash(Sha256::hash(&preimage.0).into_inner());
+		match self.send_payment_internal(route, payment_hash, &None, Some(preimage)) {
+			Ok(()) => Ok(payment_hash),
+			Err(e) => Err(e)
+		}
+	}
+
 	/// Handles the generation of a funding transaction, optionally (for tests) with a function
 	/// which checks the correctness of the funding transaction given the associated channel.
 	fn funding_transaction_generated_intern<FundingOutput: Fn(&Channel<Signer>, &Transaction) -> Result<OutPoint, APIError>>

lightning/src/ln/functional_tests.rs

@@ -1585,7 +1585,7 @@ fn test_fee_spike_violation_fails_htlc() {
 	let cur_height = nodes[1].node.best_block.read().unwrap().height() + 1;
 
 	let onion_keys = onion_utils::construct_onion_keys(&secp_ctx, &route.paths[0], &session_priv).unwrap();
-	let (onion_payloads, htlc_msat, htlc_cltv) = onion_utils::build_onion_payloads(&route.paths[0], 3460001, &Some(payment_secret), cur_height).unwrap();
+	let (onion_payloads, htlc_msat, htlc_cltv) = onion_utils::build_onion_payloads(&route.paths[0], 3460001, &Some(payment_secret), cur_height, &None).unwrap();
 	let onion_packet = onion_utils::construct_onion_packet(onion_payloads, onion_keys, [0; 32], &payment_hash);
 	let msg = msgs::UpdateAddHTLC {
 		channel_id: chan.2,
@@ -1746,7 +1746,7 @@ fn test_chan_reserve_violation_inbound_htlc_outbound_channel() {
 	let session_priv = SecretKey::from_slice(&[42; 32]).unwrap();
 	let cur_height = nodes[1].node.best_block.read().unwrap().height() + 1;
 	let onion_keys = onion_utils::construct_onion_keys(&secp_ctx, &route.paths[0], &session_priv).unwrap();
-	let (onion_payloads, htlc_msat, htlc_cltv) = onion_utils::build_onion_payloads(&route.paths[0], 1000, &Some(payment_secret), cur_height).unwrap();
+	let (onion_payloads, htlc_msat, htlc_cltv) = onion_utils::build_onion_payloads(&route.paths[0], 1000, &Some(payment_secret), cur_height, &None).unwrap();
 	let onion_packet = onion_utils::construct_onion_packet(onion_payloads, onion_keys, [0; 32], &payment_hash);
 	let msg = msgs::UpdateAddHTLC {
 		channel_id: chan.2,
@@ -1872,7 +1872,7 @@ fn test_chan_reserve_violation_inbound_htlc_inbound_chan() {
 	let session_priv = SecretKey::from_slice(&[42; 32]).unwrap();
 	let cur_height = nodes[0].node.best_block.read().unwrap().height() + 1;
 	let onion_keys = onion_utils::construct_onion_keys(&secp_ctx, &route_2.paths[0], &session_priv).unwrap();
-	let (onion_payloads, htlc_msat, htlc_cltv) = onion_utils::build_onion_payloads(&route_2.paths[0], recv_value_2, &None, cur_height).unwrap();
+	let (onion_payloads, htlc_msat, htlc_cltv) = onion_utils::build_onion_payloads(&route_2.paths[0], recv_value_2, &None, cur_height, &None).unwrap();
 	let onion_packet = onion_utils::construct_onion_packet(onion_payloads, onion_keys, [0; 32], &our_payment_hash_1);
 	let msg = msgs::UpdateAddHTLC {
 		channel_id: chan.2,
@@ -3421,7 +3421,7 @@ fn fail_backward_pending_htlc_upon_channel_failure() {
 		let current_height = nodes[1].node.best_block.read().unwrap().height() + 1;
 		let net_graph_msg_handler = &nodes[1].net_graph_msg_handler;
 		let route = get_route(&nodes[1].node.get_our_node_id(), &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[0].node.get_our_node_id(), Some(InvoiceFeatures::known()), None, &Vec::new(), 50_000, TEST_FINAL_CLTV, &logger).unwrap();
-		let (onion_payloads, _amount_msat, cltv_expiry) = onion_utils::build_onion_payloads(&route.paths[0], 50_000, &Some(payment_secret), current_height).unwrap();
+		let (onion_payloads, _amount_msat, cltv_expiry) = onion_utils::build_onion_payloads(&route.paths[0], 50_000, &Some(payment_secret), current_height, &None).unwrap();
 		let onion_keys = onion_utils::construct_onion_keys(&secp_ctx, &route.paths[0], &session_priv).unwrap();
 		let onion_routing_packet = onion_utils::construct_onion_packet(onion_payloads, onion_keys, [0; 32], &payment_hash);
 
@@ -4191,7 +4191,7 @@ 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).unwrap();
+		nodes[0].node.send_payment_along_path(&route.paths[0], &our_payment_hash, &Some(payment_secret), 200000, cur_height, &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);
@@ -6817,7 +6817,7 @@ fn test_update_add_htlc_bolt2_receiver_check_max_htlc_limit() {
 
 	let cur_height = nodes[0].node.best_block.read().unwrap().height() + 1;
 	let onion_keys = onion_utils::construct_onion_keys(&Secp256k1::signing_only(), &route.paths[0], &session_priv).unwrap();
-	let (onion_payloads, _htlc_msat, htlc_cltv) = onion_utils::build_onion_payloads(&route.paths[0], 3999999, &Some(our_payment_secret), cur_height).unwrap();
+	let (onion_payloads, _htlc_msat, htlc_cltv) = onion_utils::build_onion_payloads(&route.paths[0], 3999999, &Some(our_payment_secret), cur_height, &None).unwrap();
 	let onion_packet = onion_utils::construct_onion_packet(onion_payloads, onion_keys, [0; 32], &our_payment_hash);
 
 	let mut msg = msgs::UpdateAddHTLC {
@@ -9594,8 +9594,35 @@ fn do_test_tx_confirmed_skipping_blocks_immediate_broadcast(test_height_before_t
 		expect_payment_failure_chan_update!(nodes[0], chan_announce.contents.short_channel_id, true);
 	}
 }
+
 #[test]
 fn test_tx_confirmed_skipping_blocks_immediate_broadcast() {
 	do_test_tx_confirmed_skipping_blocks_immediate_broadcast(false);
 	do_test_tx_confirmed_skipping_blocks_immediate_broadcast(true);
 }
+
+#[test]
+fn test_keysend_payments_to_public_node() {
+	let chanmon_cfgs = create_chanmon_cfgs(2);
+	let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
+	let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
+	let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
+
+	let _chan = create_announced_chan_between_nodes_with_value(&nodes, 0, 1, 100000, 10001, InitFeatures::known(), InitFeatures::known());
+	let network_graph = nodes[0].net_graph_msg_handler.network_graph.read().unwrap();
+	let payer_pubkey = nodes[0].node.get_our_node_id();
+	let payee_pubkey = nodes[1].node.get_our_node_id();
+	let route = get_route(&payer_pubkey, &network_graph, &payee_pubkey, None,
+                        None, &vec![], 10000, 40,
+                        nodes[0].logger).unwrap();
+
+	let test_preimage = PaymentPreimage([42; 32]);
+	let payment_hash = nodes[0].node.send_spontaneous_payment(&route, Some(test_preimage)).unwrap();
+	check_added_monitors!(nodes[0], 1);
+	let mut events = nodes[0].node.get_and_clear_pending_msg_events();
+	assert_eq!(events.len(), 1);
+	let event = events.pop().unwrap();
+	let path = vec![&nodes[1]];
+	pass_along_path(&nodes[0], &path, 10000, payment_hash, PaymentSecret([0; 32]), event, true, Some(test_preimage));
+	claim_payment(&nodes[0], &path, test_preimage);
+}

lightning/src/ln/onion_route_tests.rs

@@ -327,7 +327,7 @@ fn test_onion_failure() {
 		let session_priv = SecretKey::from_slice(&[3; 32]).unwrap();
 		let cur_height = nodes[0].best_block_info().1 + 1;
 		let onion_keys = onion_utils::construct_onion_keys(&Secp256k1::new(), &route.paths[0], &session_priv).unwrap();
-		let (mut onion_payloads, _htlc_msat, _htlc_cltv) = onion_utils::build_onion_payloads(&route.paths[0], 40000, &None, cur_height).unwrap();
+		let (mut onion_payloads, _htlc_msat, _htlc_cltv) = onion_utils::build_onion_payloads(&route.paths[0], 40000, &None, cur_height, &None).unwrap();
 		let mut new_payloads = Vec::new();
 		for payload in onion_payloads.drain(..) {
 			new_payloads.push(BogusOnionHopData::new(payload));
@@ -343,7 +343,7 @@ fn test_onion_failure() {
 		let session_priv = SecretKey::from_slice(&[3; 32]).unwrap();
 		let cur_height = nodes[0].best_block_info().1 + 1;
 		let onion_keys = onion_utils::construct_onion_keys(&Secp256k1::new(), &route.paths[0], &session_priv).unwrap();
-		let (mut onion_payloads, _htlc_msat, _htlc_cltv) = onion_utils::build_onion_payloads(&route.paths[0], 40000, &None, cur_height).unwrap();
+		let (mut onion_payloads, _htlc_msat, _htlc_cltv) = onion_utils::build_onion_payloads(&route.paths[0], 40000, &None, cur_height, &None).unwrap();
 		let mut new_payloads = Vec::new();
 		for payload in onion_payloads.drain(..) {
 			new_payloads.push(BogusOnionHopData::new(payload));
@@ -537,7 +537,7 @@ fn test_onion_failure() {
 		let height = nodes[2].best_block_info().1;
 		route.paths[0][1].cltv_expiry_delta += CLTV_FAR_FAR_AWAY + route.paths[0][0].cltv_expiry_delta + 1;
 		let onion_keys = onion_utils::construct_onion_keys(&Secp256k1::new(), &route.paths[0], &session_priv).unwrap();
-		let (onion_payloads, _, htlc_cltv) = onion_utils::build_onion_payloads(&route.paths[0], 40000, &None, height).unwrap();
+		let (onion_payloads, _, htlc_cltv) = onion_utils::build_onion_payloads(&route.paths[0], 40000, &None, height, &None).unwrap();
 		let onion_packet = onion_utils::construct_onion_packet(onion_payloads, onion_keys, [0; 32], &payment_hash);
 		msg.cltv_expiry = htlc_cltv;
 		msg.onion_routing_packet = onion_packet;

lightning/src/ln/onion_utils.rs

@@ -7,7 +7,7 @@
 // You may not use this file except in accordance with one or both of these
 // licenses.
 
-use ln::{PaymentHash, PaymentSecret};
+use ln::{PaymentHash, PaymentPreimage, PaymentSecret};
 use ln::channelmanager::HTLCSource;
 use ln::msgs;
 use routing::router::RouteHop;
@@ -119,7 +119,7 @@ pub(super) fn construct_onion_keys<T: secp256k1::Signing>(secp_ctx: &Secp256k1<T
 }
 
 /// returns the hop data, as well as the first-hop value_msat and CLTV value we should send.
-pub(super) fn build_onion_payloads(path: &Vec<RouteHop>, total_msat: u64, payment_secret_option: &Option<PaymentSecret>, starting_htlc_offset: u32) -> Result<(Vec<msgs::OnionHopData>, u64, u32), APIError> {
+pub(super) fn build_onion_payloads(path: &Vec<RouteHop>, total_msat: u64, payment_secret_option: &Option<PaymentSecret>, starting_htlc_offset: u32, keysend_preimage: &Option<PaymentPreimage>) -> Result<(Vec<msgs::OnionHopData>, u64, u32), APIError> {
 	let mut cur_value_msat = 0u64;
 	let mut cur_cltv = starting_htlc_offset;
 	let mut last_short_channel_id = 0;
@@ -141,7 +141,7 @@ pub(super) fn build_onion_payloads(path: &Vec<RouteHop>, total_msat: u64, paymen
 								total_msat,
 							})
 						} else { None },
-						keysend_preimage: None,
+						keysend_preimage: *keysend_preimage,
 					}
 				} else {
 					msgs::OnionHopDataFormat::NonFinalNode {