Implement ZeroConf channel type.

Author: tnull

lightning/src/ln/channel.rs

@@ -1081,16 +1081,23 @@ impl<Signer: Sign> Channel<Signer> {
 			if channel_type.supports_any_optional_bits() {
 				return Err(ChannelError::Close("Channel Type field contained optional bits - this is not allowed".to_owned()));
 			}
-			// We currently only allow two channel types, so write it all out here - we allow
+			// We currently only allow three channel types, so write it all out here - we allow
 			// `only_static_remote_key` in all contexts, and further allow
-			// `static_remote_key|scid_privacy` if the channel is not publicly announced.
-			let mut allowed_type = ChannelTypeFeatures::only_static_remote_key();
-			if *channel_type != allowed_type {
-				allowed_type.set_scid_privacy_required();
-				if *channel_type != allowed_type {
+			// `static_remote_key | scid_privacy` or `static_remote_key | zero_conf`, if the channel
+			// is not publicly announced.
+			if *channel_type != ChannelTypeFeatures::only_static_remote_key() {
+				let mut static_remote_key_with_privacy_type = ChannelTypeFeatures::only_static_remote_key();
+				static_remote_key_with_privacy_type.set_scid_privacy_required();
+
+				let mut static_remote_key_with_zero_conf_type = ChannelTypeFeatures::only_static_remote_key();
+				static_remote_key_with_zero_conf_type.set_zero_conf_required();
+			
+				if *channel_type != static_remote_key_with_privacy_type &&
+					*channel_type != static_remote_key_with_zero_conf_type {
 					return Err(ChannelError::Close("Channel Type was not understood".to_owned()));
 				}
-				if announced_channel {
+
+				if *channel_type == static_remote_key_with_privacy_type && announced_channel {
 					return Err(ChannelError::Close("SCID Alias/Privacy Channel Type cannot be set on a public channel".to_owned()));
 				}
 			}
@@ -6407,7 +6414,7 @@ mod tests {
 	use ln::channelmanager::{HTLCSource, PaymentId};
 	use ln::channel::{Channel, InboundHTLCOutput, OutboundHTLCOutput, InboundHTLCState, OutboundHTLCState, HTLCCandidate, HTLCInitiator};
 	use ln::channel::{MAX_FUNDING_SATOSHIS_NO_WUMBO, TOTAL_BITCOIN_SUPPLY_SATOSHIS};
-	use ln::features::InitFeatures;
+	use ln::features::{InitFeatures, ChannelTypeFeatures};
 	use ln::msgs::{ChannelUpdate, DataLossProtect, DecodeError, OptionalField, UnsignedChannelUpdate};
 	use ln::script::ShutdownScript;
 	use ln::chan_utils;
@@ -7722,4 +7729,27 @@ mod tests {
 		assert_eq!(chan_utils::derive_private_revocation_key(&secp_ctx, &per_commitment_secret, &base_secret).unwrap(),
 				SecretKey::from_slice(&hex::decode("d09ffff62ddb2297ab000cc85bcb4283fdeb6aa052affbc9dddcf33b61078110").unwrap()[..]).unwrap());
 	}
+
+	#[test]
+	fn test_zero_conf_channel_type_support() {
+		let feeest = TestFeeEstimator{fee_est: 15000};
+		let secp_ctx = Secp256k1::new();
+		let seed = [42; 32];
+		let network = Network::Testnet;
+		let keys_provider = test_utils::TestKeysInterface::new(&seed, network);
+		let logger = test_utils::TestLogger::new();
+
+		let node_b_node_id = PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[42; 32]).unwrap());
+		let config = UserConfig::default();
+		let node_a_chan = Channel::<EnforcingSigner>::new_outbound(&&feeest, &&keys_provider, node_b_node_id, &InitFeatures::known(), 10000000, 100000, 42, &config, 0, 42).unwrap();
+
+		let mut channel_type_features = ChannelTypeFeatures::only_static_remote_key();
+		channel_type_features.set_zero_conf_required();
+
+		let mut open_channel_msg = node_a_chan.get_open_channel(genesis_block(network).header.block_hash());
+		open_channel_msg.channel_type = Some(channel_type_features);
+		let node_b_node_id = PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[7; 32]).unwrap());
+		let res = Channel::<EnforcingSigner>::new_from_req(&&feeest, &&keys_provider, node_b_node_id, &InitFeatures::known(), &open_channel_msg, 7, &config, 0, &&logger, 42);
+		assert!(res.is_ok());
+	}
 }

lightning/src/ln/channelmanager.rs

@@ -4200,7 +4200,11 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
 				if *counterparty_node_id != channel.get().get_counterparty_node_id() {
 					return Err(APIError::APIMisuseError { err: "The passed counterparty_node_id doesn't match the channel's counterparty node_id".to_owned() });
 				}
-				if accept_0conf { channel.get_mut().set_0conf(); }
+				if accept_0conf {
+					channel.get_mut().set_0conf();
+				} else if channel.get().get_channel_type().requires_zero_conf() {
+					return Err(APIError::APIMisuseError { err: "This channel requires 0conf. Please use accept_inbound_channel_from_trusted_peer_0conf to accept.".to_owned() });
+				}
 				channel_state.pending_msg_events.push(events::MessageSendEvent::SendAcceptChannel {
 					node_id: channel.get().get_counterparty_node_id(),
 					msg: channel.get_mut().accept_inbound_channel(user_channel_id),
@@ -4242,6 +4246,9 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
 			},
 			hash_map::Entry::Vacant(entry) => {
 				if !self.default_configuration.manually_accept_inbound_channels {
+					if channel.get_channel_type().requires_zero_conf() {
+						return Err(MsgHandleErrInternal::send_err_msg_no_close("No zero confirmation channels accepted".to_owned(), msg.temporary_channel_id.clone()));
+					}
 					channel_state.pending_msg_events.push(events::MessageSendEvent::SendAcceptChannel {
 						node_id: counterparty_node_id.clone(),
 						msg: channel.accept_inbound_channel(0),

lightning/src/ln/features.rs

@@ -217,7 +217,7 @@ mod sealed {
 			// Byte 4
 			,
 			// Byte 5
-			SCIDPrivacy,
+			SCIDPrivacy | ZeroConf,
 		],
 		optional_features: [
 			// Byte 0
@@ -402,7 +402,9 @@ mod sealed {
 	define_feature!(47, SCIDPrivacy, [InitContext, NodeContext, ChannelTypeContext],
 		"Feature flags for only forwarding with SCID aliasing. Called `option_scid_alias` in the BOLTs",
 		set_scid_privacy_optional, set_scid_privacy_required, supports_scid_privacy, requires_scid_privacy);
-
+	define_feature!(51, ZeroConf, [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!(55, Keysend, [NodeContext],
 		"Feature flags for keysend payments.", set_keysend_optional, set_keysend_required,
 		supports_keysend, requires_keysend);
@@ -852,14 +854,19 @@ mod tests {
 
 		assert!(InitFeatures::known().supports_scid_privacy());
 		assert!(NodeFeatures::known().supports_scid_privacy());
+		assert!(ChannelTypeFeatures::known().supports_scid_privacy());
 		assert!(!InitFeatures::known().requires_scid_privacy());
 		assert!(!NodeFeatures::known().requires_scid_privacy());
+		assert!(ChannelTypeFeatures::known().requires_scid_privacy());
 
 		assert!(InitFeatures::known().supports_wumbo());
 		assert!(NodeFeatures::known().supports_wumbo());
 		assert!(!InitFeatures::known().requires_wumbo());
 		assert!(!NodeFeatures::known().requires_wumbo());
 
+		assert!(!ChannelTypeFeatures::known().supports_zero_conf());
+		assert!(!ChannelTypeFeatures::known().requires_zero_conf());
+
 		let mut init_features = InitFeatures::known();
 		assert!(init_features.initial_routing_sync());
 		init_features.clear_initial_routing_sync();

lightning/src/util/events.rs

@@ -466,6 +466,12 @@ pub enum Event {
 		/// the resulting [`ChannelManager`] will not be readable by versions of LDK prior to
 		/// 0.0.106.
 		///
+		/// Furthermore, note that if [`ChannelTypeFeatures::supports_zero_conf`] returns true on this type,
+		/// the resulting [`ChannelManager`] will not be readable by versions of LDK prior to
+		/// 0.0.107. Channels setting this type also need to get manually accepted via
+		/// [`crate::ln::channelmanager::ChannelManager::accept_inbound_channel_from_trusted_peer_0conf`],
+		/// or will be rejected otherwise.
+		///
 		/// [`ChannelManager`]: crate::ln::channelmanager::ChannelManager
 		channel_type: ChannelTypeFeatures,
 	},