Async send always-online counterparty side

lightning-dns-resolver/src/lib.rs

@@ -239,8 +239,7 @@ mod test {
 				context,
 				&keys,
 				secp_ctx,
-			)
-			.unwrap()])
+			)])
 		}
 	}
 	impl Deref for DirectlyConnectedRouter {
@@ -349,8 +348,7 @@ mod test {
 			query_context,
 			&*payer_keys,
 			&secp_ctx,
-		)
-		.unwrap();
+		);
 		payer.pending_messages.lock().unwrap().push((
 			DNSResolverMessage::DNSSECQuery(msg),
 			MessageSendInstructions::WithSpecifiedReplyPath {

lightning-types/src/features.rs

@@ -80,6 +80,8 @@
 //!   (see [BOLT-2](https://github.com/lightning/bolts/blob/master/02-peer-protocol.md#channel-quiescence) for more information).
 //! - `ZeroFeeCommitments` - A channel type which always uses zero transaction fee on commitment transactions.
 //!   (see [BOLT PR #1228](https://github.com/lightning/bolts/pull/1228) for more info).
+//! - `HtlcHold` - requires/supports holding HTLCs and forwarding on receipt of an onion message
+//!   (see [BOLT-2](https://github.com/lightning/bolts/pull/989/files) for more information).
 //!
 //! LDK knows about the following features, but does not support them:
 //! - `AnchorsNonzeroFeeHtlcTx` - the initial version of anchor outputs, which was later found to be
@@ -161,7 +163,7 @@ mod sealed {
 			// Byte 5
 			ProvideStorage | ChannelType | SCIDPrivacy | AnchorZeroFeeCommitments,
 			// Byte 6
-			ZeroConf,
+			ZeroConf | HtlcHold,
 			// Byte 7
 			Trampoline | SimpleClose,
 		]
@@ -182,7 +184,7 @@ mod sealed {
 			// Byte 5
 			ProvideStorage | ChannelType | SCIDPrivacy | AnchorZeroFeeCommitments,
 			// Byte 6
-			ZeroConf | Keysend,
+			ZeroConf | HtlcHold | Keysend,
 			// Byte 7
 			Trampoline | SimpleClose,
 			// Byte 8 - 31
@@ -640,6 +642,17 @@ mod sealed {
 	define_feature!(51, ZeroConf, [InitContext, NodeContext, ChannelTypeContext],
 		"Feature flags for accepting channels with zero confirmations. Called `option_zeroconf` in the BOLTs",
 		set_zero_conf_optional, set_zero_conf_required, supports_zero_conf, requires_zero_conf);
+	define_feature!(
+		53,
+		HtlcHold,
+		[InitContext, NodeContext],
+		"Feature flags for holding HTLCs and forwarding on receipt of an onion message",
+		set_htlc_hold_optional,
+		set_htlc_hold_required,
+		clear_htlc_hold,
+		supports_htlc_hold,
+		requires_htlc_hold
+	);
 	define_feature!(
 		55,
 		Keysend,

lightning/src/blinded_path/message.rs

@@ -19,7 +19,7 @@ use crate::blinded_path::{BlindedHop, BlindedPath, Direction, IntroductionNode,
 use crate::crypto::streams::ChaChaPolyReadAdapter;
 use crate::io;
 use crate::io::Cursor;
-use crate::ln::channelmanager::PaymentId;
+use crate::ln::channelmanager::{InterceptId, PaymentId};
 use crate::ln::msgs::DecodeError;
 use crate::ln::onion_utils;
 use crate::offers::nonce::Nonce;
@@ -57,23 +57,19 @@ impl BlindedMessagePath {
 	pub fn one_hop<ES: Deref, T: secp256k1::Signing + secp256k1::Verification>(
 		recipient_node_id: PublicKey, local_node_receive_key: ReceiveAuthKey,
 		context: MessageContext, entropy_source: ES, secp_ctx: &Secp256k1<T>,
-	) -> Result<Self, ()>
+	) -> Self
 	where
 		ES::Target: EntropySource,
 	{
 		Self::new(&[], recipient_node_id, local_node_receive_key, context, entropy_source, secp_ctx)
 	}
 
-	/// Create a path for an onion message, to be forwarded along `node_pks`. The last node
-	/// pubkey in `node_pks` will be the destination node.
-	///
-	/// Errors if no hops are provided or if `node_pk`(s) are invalid.
-	//  TODO: make all payloads the same size with padding + add dummy hops
+	/// Create a path for an onion message, to be forwarded along `node_pks`.
 	pub fn new<ES: Deref, T: secp256k1::Signing + secp256k1::Verification>(
 		intermediate_nodes: &[MessageForwardNode], recipient_node_id: PublicKey,
 		local_node_receive_key: ReceiveAuthKey, context: MessageContext, entropy_source: ES,
 		secp_ctx: &Secp256k1<T>,
-	) -> Result<Self, ()>
+	) -> Self
 	where
 		ES::Target: EntropySource,
 	{
@@ -96,7 +92,7 @@ impl BlindedMessagePath {
 		intermediate_nodes: &[MessageForwardNode], recipient_node_id: PublicKey,
 		dummy_hop_count: usize, local_node_receive_key: ReceiveAuthKey, context: MessageContext,
 		entropy_source: ES, secp_ctx: &Secp256k1<T>,
-	) -> Result<Self, ()>
+	) -> Self
 	where
 		ES::Target: EntropySource,
 	{
@@ -107,7 +103,7 @@ impl BlindedMessagePath {
 		let blinding_secret =
 			SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
 
-		Ok(Self(BlindedPath {
+		Self(BlindedPath {
 			introduction_node,
 			blinding_point: PublicKey::from_secret_key(secp_ctx, &blinding_secret),
 			blinded_hops: blinded_hops(
@@ -118,9 +114,8 @@ impl BlindedMessagePath {
 				context,
 				&blinding_secret,
 				local_node_receive_key,
-			)
-			.map_err(|_| ())?,
-		}))
+			),
+		})
 	}
 
 	/// Attempts to a use a compact representation for the [`IntroductionNode`] by using a directed
@@ -561,7 +556,7 @@ pub enum AsyncPaymentsContext {
 	},
 	/// Context contained within the reply [`BlindedMessagePath`] we put in outbound
 	/// [`HeldHtlcAvailable`] messages, provided back to us in corresponding [`ReleaseHeldHtlc`]
-	/// messages.
+	/// messages if we are an always-online sender paying an async recipient.
 	///
 	/// [`HeldHtlcAvailable`]: crate::onion_message::async_payments::HeldHtlcAvailable
 	/// [`ReleaseHeldHtlc`]: crate::onion_message::async_payments::ReleaseHeldHtlc
@@ -582,6 +577,17 @@ pub enum AsyncPaymentsContext {
 		/// able to trivially ask if we're online forever.
 		path_absolute_expiry: core::time::Duration,
 	},
+	/// Context contained within the reply [`BlindedMessagePath`] put in outbound
+	/// [`HeldHtlcAvailable`] messages, provided back to the async sender's always-online counterparty
+	/// in corresponding [`ReleaseHeldHtlc`] messages.
+	///
+	/// [`HeldHtlcAvailable`]: crate::onion_message::async_payments::HeldHtlcAvailable
+	/// [`ReleaseHeldHtlc`]: crate::onion_message::async_payments::ReleaseHeldHtlc
+	ReleaseHeldHtlc {
+		/// An identifier for the HTLC that should be released by us as the sender's always-online
+		/// channel counterparty to the often-offline recipient.
+		intercept_id: InterceptId,
+	},
 }
 
 impl_writeable_tlv_based_enum!(MessageContext,
@@ -637,6 +643,9 @@ impl_writeable_tlv_based_enum!(AsyncPaymentsContext,
 		(2, invoice_slot, required),
 		(4, path_absolute_expiry, required),
 	},
+	(6, ReleaseHeldHtlc) => {
+		(0, intercept_id, required),
+	},
 );
 
 /// Contains a simple nonce for use in a blinded path's context.
@@ -669,7 +678,7 @@ pub(super) fn blinded_hops<T: secp256k1::Signing + secp256k1::Verification>(
 	secp_ctx: &Secp256k1<T>, intermediate_nodes: &[MessageForwardNode],
 	recipient_node_id: PublicKey, dummy_hop_count: usize, context: MessageContext,
 	session_priv: &SecretKey, local_node_receive_key: ReceiveAuthKey,
-) -> Result<Vec<BlindedHop>, secp256k1::Error> {
+) -> Vec<BlindedHop> {
 	let dummy_count = cmp::min(dummy_hop_count, MAX_DUMMY_HOPS_COUNT);
 	let pks = intermediate_nodes
 		.iter()

lightning/src/blinded_path/payment.rs

@@ -116,7 +116,6 @@ impl BlindedPaymentPath {
 	/// Create a blinded path for a payment, to be forwarded along `intermediate_nodes`.
 	///
 	/// Errors if:
-	/// * a provided node id is invalid
 	/// * [`BlindedPayInfo`] calculation results in an integer overflow
 	/// * any unknown features are required in the provided [`ForwardTlvs`]
 	//  TODO: make all payloads the same size with padding + add dummy hops
@@ -151,8 +150,7 @@ impl BlindedPaymentPath {
 					payee_node_id,
 					payee_tlvs,
 					&blinding_secret,
-				)
-				.map_err(|_| ())?,
+				),
 			},
 			payinfo: blinded_payinfo,
 		})
@@ -663,7 +661,7 @@ pub(crate) const PAYMENT_PADDING_ROUND_OFF: usize = 30;
 pub(super) fn blinded_hops<T: secp256k1::Signing + secp256k1::Verification>(
 	secp_ctx: &Secp256k1<T>, intermediate_nodes: &[PaymentForwardNode], payee_node_id: PublicKey,
 	payee_tlvs: ReceiveTlvs, session_priv: &SecretKey,
-) -> Result<Vec<BlindedHop>, secp256k1::Error> {
+) -> Vec<BlindedHop> {
 	let pks = intermediate_nodes
 		.iter()
 		.map(|node| (node.node_id, None))

lightning/src/blinded_path/utils.rs

@@ -51,10 +51,8 @@ macro_rules! build_keys_helper {
 						hmac.input(encrypted_data_ss.as_ref());
 						Hmac::from_engine(hmac).to_byte_array()
 					};
-					pk.mul_tweak(
-						$secp_ctx,
-						&Scalar::from_be_bytes(hop_pk_blinding_factor).unwrap(),
-					)?
+					pk.mul_tweak($secp_ctx, &Scalar::from_be_bytes(hop_pk_blinding_factor).unwrap())
+						.expect("RNG is busted")
 				};
 				let onion_packet_ss = SharedSecret::new(&blinded_hop_pk, &onion_packet_pubkey_priv);
 
@@ -84,9 +82,9 @@ macro_rules! build_keys_helper {
 					Sha256::from_engine(sha).to_byte_array()
 				};
 
-				msg_blinding_point_priv = msg_blinding_point_priv.mul_tweak(
-					&Scalar::from_be_bytes(msg_blinding_point_blinding_factor).unwrap(),
-				)?;
+				msg_blinding_point_priv = msg_blinding_point_priv
+					.mul_tweak(&Scalar::from_be_bytes(msg_blinding_point_blinding_factor).unwrap())
+					.expect("RNG is busted");
 				msg_blinding_point =
 					PublicKey::from_secret_key($secp_ctx, &msg_blinding_point_priv);
 
@@ -96,9 +94,9 @@ macro_rules! build_keys_helper {
 					sha.input(onion_packet_ss.as_ref());
 					Sha256::from_engine(sha).to_byte_array()
 				};
-				onion_packet_pubkey_priv = onion_packet_pubkey_priv.mul_tweak(
-					&Scalar::from_be_bytes(onion_packet_pubkey_blinding_factor).unwrap(),
-				)?;
+				onion_packet_pubkey_priv = onion_packet_pubkey_priv
+					.mul_tweak(&Scalar::from_be_bytes(onion_packet_pubkey_blinding_factor).unwrap())
+					.expect("RNG is busted");
 				onion_packet_pubkey =
 					PublicKey::from_secret_key($secp_ctx, &onion_packet_pubkey_priv);
 			};
@@ -109,8 +107,7 @@ macro_rules! build_keys_helper {
 pub(crate) fn construct_keys_for_onion_message<'a, T, I, F>(
 	secp_ctx: &Secp256k1<T>, unblinded_path: I, destination: Destination, session_priv: &SecretKey,
 	mut callback: F,
-) -> Result<(), secp256k1::Error>
-where
+) where
 	T: secp256k1::Signing + secp256k1::Verification,
 	I: Iterator<Item = PublicKey>,
 	F: FnMut(SharedSecret, PublicKey, [u8; 32], Option<PublicKey>, Option<Vec<u8>>),
@@ -134,13 +131,11 @@ where
 			}
 		},
 	}
-	Ok(())
 }
 
 fn construct_keys_for_blinded_path<'a, T, I, F, H>(
 	secp_ctx: &Secp256k1<T>, unblinded_path: I, session_priv: &SecretKey, mut callback: F,
-) -> Result<(), secp256k1::Error>
-where
+) where
 	T: secp256k1::Signing + secp256k1::Verification,
 	H: Borrow<PublicKey>,
 	I: Iterator<Item = H>,
@@ -151,7 +146,6 @@ where
 	for pk in unblinded_path {
 		build_keys_in_loop!(pk, false, None);
 	}
-	Ok(())
 }
 
 struct PublicKeyWithTlvs<W: Writeable> {
@@ -168,7 +162,7 @@ impl<W: Writeable> Borrow<PublicKey> for PublicKeyWithTlvs<W> {
 
 pub(crate) fn construct_blinded_hops<'a, T, I, W>(
 	secp_ctx: &Secp256k1<T>, unblinded_path: I, session_priv: &SecretKey,
-) -> Result<Vec<BlindedHop>, secp256k1::Error>
+) -> Vec<BlindedHop>
 where
 	T: secp256k1::Signing + secp256k1::Verification,
 	I: Iterator<Item = ((PublicKey, Option<ReceiveAuthKey>), W)>,
@@ -194,8 +188,8 @@ where
 				),
 			});
 		},
-	)?;
-	Ok(blinded_hops)
+	);
+	blinded_hops
 }
 
 /// Encrypt TLV payload to be used as a [`crate::blinded_path::BlindedHop::encrypted_payload`].

lightning/src/ln/blinded_payment_tests.rs

@@ -1522,6 +1522,7 @@ fn update_add_msg(
 		onion_routing_packet,
 		skimmed_fee_msat: None,
 		blinding_point,
+		hold_htlc: None,
 	}
 }
 
@@ -1552,7 +1553,7 @@ fn route_blinding_spec_test_vector() {
 	];
 	let mut dave_eve_blinded_hops = blinded_path::utils::construct_blinded_hops(
 		&secp_ctx, path.into_iter(), &dave_eve_session_priv,
-	).unwrap();
+	);
 
 	// Concatenate an additional Bob -> Carol blinded path to the Eve -> Dave blinded path.
 	let bob_carol_session_priv = secret_from_hex("0202020202020202020202020202020202020202020202020202020202020202");
@@ -1563,7 +1564,7 @@ fn route_blinding_spec_test_vector() {
 	];
 	let bob_carol_blinded_hops = blinded_path::utils::construct_blinded_hops(
 		&secp_ctx, path.into_iter(), &bob_carol_session_priv,
-	).unwrap();
+	);
 
 	let mut blinded_hops = bob_carol_blinded_hops;
 	blinded_hops.append(&mut dave_eve_blinded_hops);
@@ -2030,7 +2031,7 @@ fn do_test_trampoline_single_hop_receive(success: bool) {
 		let path = [((carol_node_id, None), WithoutLength(&carol_unblinded_tlvs))];
 		blinded_path::utils::construct_blinded_hops(
 			&secp_ctx, path.into_iter(), &carol_alice_trampoline_session_priv,
-		).unwrap()
+		)
 	} else {
 		let payee_tlvs = blinded_path::payment::TrampolineForwardTlvs {
 			next_trampoline: alice_node_id,
@@ -2051,7 +2052,7 @@ fn do_test_trampoline_single_hop_receive(success: bool) {
 		let path = [((carol_node_id, None), WithoutLength(&carol_unblinded_tlvs))];
 		blinded_path::utils::construct_blinded_hops(
 			&secp_ctx, path.into_iter(), &carol_alice_trampoline_session_priv,
-		).unwrap()
+		)
 	};
 
 	let route = Route {
@@ -2255,7 +2256,7 @@ fn test_trampoline_unblinded_receive() {
 	let carol_blinding_point = PublicKey::from_secret_key(&secp_ctx, &carol_alice_trampoline_session_priv);
 	let carol_blinded_hops = blinded_path::utils::construct_blinded_hops(
 		&secp_ctx, path.into_iter(), &carol_alice_trampoline_session_priv,
-	).unwrap();
+	);
 
 	let route = Route {
 		paths: vec![Path {