Introduce interactive signing state flags for funded states.

fuzz/src/full_stack.rs

@@ -1090,7 +1090,7 @@ fn two_peer_forwarding_seed() -> Vec<u8> {
 	// our network key
 	ext_from_hex("0100000000000000000000000000000000000000000000000000000000000000", &mut test);
 	// config
-	ext_from_hex("0000000000900000000000000000640001000000000001ffff0000000000000000ffffffffffffffffffffffffffffffff0000000000000000ffffffffffffffff000000ffffffff00ffff1a000400010000020400000000040200000a08ffffffffffffffff0001000000", &mut test);
+	ext_from_hex("0000000000900000000000000000640001000000000001ffff0000000000000000ffffffffffffffffffffffffffffffff0000000000000000ffffffffffffffff000000ffffffff00ffff1a000400010000020400000000040200000a08ffffffffffffffff000100000000", &mut test);
 
 	// new outbound connection with id 0
 	ext_from_hex("00", &mut test);
@@ -1606,7 +1606,7 @@ fn gossip_exchange_seed() -> Vec<u8> {
 	// our network key
 	ext_from_hex("0100000000000000000000000000000000000000000000000000000000000000", &mut test);
 	// config
-	ext_from_hex("0000000000900000000000000000640001000000000001ffff0000000000000000ffffffffffffffffffffffffffffffff0000000000000000ffffffffffffffff000000ffffffff00ffff1a000400010000020400000000040200000a08ffffffffffffffff0001000000", &mut test);
+	ext_from_hex("0000000000900000000000000000640001000000000001ffff0000000000000000ffffffffffffffffffffffffffffffff0000000000000000ffffffffffffffff000000ffffffff00ffff1a000400010000020400000000040200000a08ffffffffffffffff000100000000", &mut test);
 
 	// new outbound connection with id 0
 	ext_from_hex("00", &mut test);

lightning/src/ln/channelmanager.rs

@@ -3253,7 +3253,7 @@ macro_rules! handle_monitor_update_completion {
 			&mut $peer_state.pending_msg_events, $chan, updates.raa,
 			updates.commitment_update, updates.order, updates.accepted_htlcs, updates.pending_update_adds,
 			updates.funding_broadcastable, updates.channel_ready,
-			updates.announcement_sigs, updates.tx_signatures);
+			updates.announcement_sigs, updates.tx_signatures, None);
 		if let Some(upd) = channel_update {
 			$peer_state.pending_msg_events.push(upd);
 		}
@@ -7665,10 +7665,10 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
 		pending_forwards: Vec<(PendingHTLCInfo, u64)>, pending_update_adds: Vec<msgs::UpdateAddHTLC>,
 		funding_broadcastable: Option<Transaction>,
 		channel_ready: Option<msgs::ChannelReady>, announcement_sigs: Option<msgs::AnnouncementSignatures>,
-		tx_signatures: Option<msgs::TxSignatures>
+		tx_signatures: Option<msgs::TxSignatures>, tx_abort: Option<msgs::TxAbort>,
 	) -> (Option<(u64, Option<PublicKey>, OutPoint, ChannelId, u128, Vec<(PendingHTLCInfo, u64)>)>, Option<(u64, Vec<msgs::UpdateAddHTLC>)>) {
 		let logger = WithChannelContext::from(&self.logger, &channel.context, None);
-		log_trace!(logger, "Handling channel resumption for channel {} with {} RAA, {} commitment update, {} pending forwards, {} pending update_add_htlcs, {}broadcasting funding, {} channel ready, {} announcement, {} tx_signatures",
+		log_trace!(logger, "Handling channel resumption for channel {} with {} RAA, {} commitment update, {} pending forwards, {} pending update_add_htlcs, {}broadcasting funding, {} channel ready, {} announcement, {} tx_signatures, {} tx_abort",
 			&channel.context.channel_id(),
 			if raa.is_some() { "an" } else { "no" },
 			if commitment_update.is_some() { "a" } else { "no" },
@@ -7677,6 +7677,7 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
 			if channel_ready.is_some() { "sending" } else { "without" },
 			if announcement_sigs.is_some() { "sending" } else { "without" },
 			if tx_signatures.is_some() { "sending" } else { "without" },
+			if tx_abort.is_some() { "sending" } else { "without" },
 		);
 
 		let counterparty_node_id = channel.context.get_counterparty_node_id();
@@ -7710,6 +7711,12 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
 				msg,
 			});
 		}
+		if let Some(msg) = tx_abort {
+			pending_msg_events.push(MessageSendEvent::SendTxAbort {
+				node_id: counterparty_node_id,
+				msg,
+			});
+		}
 
 		macro_rules! handle_cs { () => {
 			if let Some(update) = commitment_update {
@@ -8583,14 +8590,14 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
 				match chan_entry.get_mut().as_funded_mut() {
 					Some(chan) => {
 						let logger = WithChannelContext::from(&self.logger, &chan.context, None);
-						let tx_signatures_opt = try_channel_entry!(self, peer_state, chan.tx_signatures(msg, &&logger), chan_entry);
+						let (funding_tx_opt, tx_signatures_opt) = try_channel_entry!(self, peer_state, chan.tx_signatures(msg, &&logger), chan_entry);
 						if let Some(tx_signatures) = tx_signatures_opt {
 							peer_state.pending_msg_events.push(MessageSendEvent::SendTxSignatures {
 								node_id: *counterparty_node_id,
 								msg: tx_signatures,
 							});
 						}
-						if let Some(ref funding_tx) = chan.context.unbroadcasted_funding(&chan.funding) {
+						if let Some(ref funding_tx) = funding_tx_opt {
 							self.tx_broadcaster.broadcast_transactions(&[funding_tx]);
 							{
 								let mut pending_events = self.pending_events.lock().unwrap();
@@ -9491,7 +9498,8 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
 						let need_lnd_workaround = chan.context.workaround_lnd_bug_4006.take();
 						let (htlc_forwards, decode_update_add_htlcs) = self.handle_channel_resumption(
 							&mut peer_state.pending_msg_events, chan, responses.raa, responses.commitment_update, responses.order,
-							Vec::new(), Vec::new(), None, responses.channel_ready, responses.announcement_sigs, None);
+							Vec::new(), Vec::new(), None, responses.channel_ready, responses.announcement_sigs,
+							responses.tx_signatures, responses.tx_abort);
 						debug_assert!(htlc_forwards.is_none());
 						debug_assert!(decode_update_add_htlcs.is_none());
 						if let Some(upd) = channel_update {
@@ -12006,6 +12014,12 @@ where
 	}
 
 	fn handle_open_channel_v2(&self, counterparty_node_id: PublicKey, msg: &msgs::OpenChannelV2) {
+		if !self.init_features().supports_dual_fund() {
+			let _: Result<(), _> = handle_error!(self, Err(MsgHandleErrInternal::send_err_msg_no_close(
+				"Dual-funded channels not supported".to_owned(),
+				msg.common_fields.temporary_channel_id.clone())), counterparty_node_id);
+			return;
+		}
 		// Note that we never need to persist the updated ChannelManager for an inbound
 		// open_channel message - pre-funded channels are never written so there should be no
 		// change to the contents.
@@ -12926,7 +12940,9 @@ pub fn provided_init_features(config: &UserConfig) -> InitFeatures {
 	if config.channel_handshake_config.negotiate_anchors_zero_fee_htlc_tx {
 		features.set_anchors_zero_fee_htlc_tx_optional();
 	}
-	features.set_dual_fund_optional();
+	if config.enable_dual_funded_channels {
+		features.set_dual_fund_optional();
+	}
 	// Only signal quiescence support in tests for now, as we don't yet support any
 	// quiescent-dependent protocols (e.g., splicing).
 	#[cfg(any(test, fuzzing))]

lightning/src/ln/dual_funding_tests.rs

@@ -39,7 +39,9 @@ struct V2ChannelEstablishmentTestSession {
 fn do_test_v2_channel_establishment(session: V2ChannelEstablishmentTestSession) {
 	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 mut node_1_user_config = test_default_channel_config();
+	node_1_user_config.enable_dual_funded_channels = true;
+	let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, Some(node_1_user_config)]);
 	let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
 	let logger_a = test_utils::TestLogger::with_id("node a".to_owned());
 
@@ -206,13 +208,6 @@ fn do_test_v2_channel_establishment(session: V2ChannelEstablishmentTestSession)
 	assert!(events.is_empty());
 	nodes[1].chain_monitor.complete_sole_pending_chan_update(&channel_id);
 
-	let events = nodes[1].node.get_and_clear_pending_events();
-	assert_eq!(events.len(), 1);
-	match events[0] {
-		Event::ChannelPending { channel_id: chan_id, .. } => assert_eq!(chan_id, channel_id),
-		_ => panic!("Unexpected event"),
-	};
-
 	let tx_signatures_msg = get_event_msg!(
 		nodes[1],
 		MessageSendEvent::SendTxSignatures,
@@ -234,6 +229,13 @@ fn do_test_v2_channel_establishment(session: V2ChannelEstablishmentTestSession)
 		},
 	);
 
+	let events = nodes[1].node.get_and_clear_pending_events();
+	assert_eq!(events.len(), 1);
+	match events[0] {
+		Event::ChannelPending { channel_id: chan_id, .. } => assert_eq!(chan_id, channel_id),
+		_ => panic!("Unexpected event"),
+	};
+
 	// For an inbound channel V2 channel the transaction should be broadcast once receiving a
 	// tx_signature and applying local tx_signatures:
 	let broadcasted_txs = nodes[1].tx_broadcaster.txn_broadcast();

lightning/src/ln/interactivetxs.rs

@@ -189,6 +189,18 @@ pub(crate) struct ConstructedTransaction {
 	holder_sends_tx_signatures_first: bool,
 }
 
+impl_writeable_tlv_based!(ConstructedTransaction, {
+	(1, holder_is_initiator, required),
+	(3, inputs, required),
+	(5, outputs, required),
+	(7, local_inputs_value_satoshis, required),
+	(9, local_outputs_value_satoshis, required),
+	(11, remote_inputs_value_satoshis, required),
+	(13, remote_outputs_value_satoshis, required),
+	(15, lock_time, required),
+	(17, holder_sends_tx_signatures_first, required),
+});
+
 impl ConstructedTransaction {
 	fn new(context: NegotiationContext) -> Self {
 		let local_inputs_value_satoshis = context
@@ -309,25 +321,32 @@ impl ConstructedTransaction {
 /// https://github.com/lightning/bolts/blob/master/02-peer-protocol.md#sharing-funding-signatures-tx_signatures
 #[derive(Debug, Clone, PartialEq)]
 pub(crate) struct InteractiveTxSigningSession {
-	pub unsigned_tx: ConstructedTransaction,
+	unsigned_tx: ConstructedTransaction,
 	holder_sends_tx_signatures_first: bool,
-	received_commitment_signed: bool,
+	has_received_commitment_signed: bool,
 	holder_tx_signatures: Option<TxSignatures>,
-	counterparty_sent_tx_signatures: bool,
 }
 
 impl InteractiveTxSigningSession {
-	pub fn received_commitment_signed(&mut self) -> Option<TxSignatures> {
-		self.received_commitment_signed = true;
-		if self.holder_sends_tx_signatures_first {
-			self.holder_tx_signatures.clone()
-		} else {
-			None
-		}
+	pub fn unsigned_tx(&self) -> &ConstructedTransaction {
+		&self.unsigned_tx
+	}
+
+	pub fn holder_sends_tx_signatures_first(&self) -> bool {
+		self.holder_sends_tx_signatures_first
+	}
+
+	pub fn has_received_commitment_signed(&self) -> bool {
+		self.has_received_commitment_signed
+	}
+
+	pub fn holder_tx_signatures(&self) -> &Option<TxSignatures> {
+		&self.holder_tx_signatures
 	}
 
-	pub fn get_tx_signatures(&self) -> Option<TxSignatures> {
-		if self.received_commitment_signed {
+	pub fn received_commitment_signed(&mut self) -> Option<TxSignatures> {
+		self.has_received_commitment_signed = true;
+		if self.holder_sends_tx_signatures_first {
 			self.holder_tx_signatures.clone()
 		} else {
 			None
@@ -352,7 +371,6 @@ impl InteractiveTxSigningSession {
 			return Err(());
 		}
 		self.unsigned_tx.add_remote_witnesses(tx_signatures.witnesses.clone());
-		self.counterparty_sent_tx_signatures = true;
 
 		let holder_tx_signatures = if !self.holder_sends_tx_signatures_first {
 			self.holder_tx_signatures.clone()
@@ -433,6 +451,13 @@ impl InteractiveTxSigningSession {
 	}
 }
 
+impl_writeable_tlv_based!(InteractiveTxSigningSession, {
+	(1, unsigned_tx, required),
+	(3, holder_sends_tx_signatures_first, required),
+	(5, has_received_commitment_signed, required),
+	(7, holder_tx_signatures, required),
+});
+
 #[derive(Debug)]
 struct NegotiationContext {
 	holder_node_id: PublicKey,
@@ -1008,9 +1033,8 @@ macro_rules! define_state_transitions {
 				let signing_session = InteractiveTxSigningSession {
 					holder_sends_tx_signatures_first: tx.holder_sends_tx_signatures_first,
 					unsigned_tx: tx,
-					received_commitment_signed: false,
+					has_received_commitment_signed: false,
 					holder_tx_signatures: None,
-					counterparty_sent_tx_signatures: false,
 				};
 				Ok(NegotiationComplete(signing_session))
 			}
@@ -1157,6 +1181,11 @@ enum AddingRole {
 	Remote,
 }
 
+impl_writeable_tlv_based_enum!(AddingRole,
+	(1, Local) => {},
+	(3, Remote) => {},
+);
+
 /// Represents an input -- local or remote (both have the same fields)
 #[derive(Clone, Debug, Eq, PartialEq)]
 pub struct LocalOrRemoteInput {
@@ -1165,19 +1194,35 @@ pub struct LocalOrRemoteInput {
 	prev_output: TxOut,
 }
 
+impl_writeable_tlv_based!(LocalOrRemoteInput, {
+	(1, serial_id, required),
+	(3, input, required),
+	(5, prev_output, required),
+});
+
 #[derive(Clone, Debug, Eq, PartialEq)]
 pub(crate) enum InteractiveTxInput {
 	Local(LocalOrRemoteInput),
 	Remote(LocalOrRemoteInput),
 	// TODO(splicing) SharedInput should be added
 }
 
+impl_writeable_tlv_based_enum!(InteractiveTxInput,
+	{1, Local} => (),
+	{3, Remote} => (),
+);
+
 #[derive(Clone, Debug, Eq, PartialEq)]
 pub(super) struct SharedOwnedOutput {
 	tx_out: TxOut,
 	local_owned: u64,
 }
 
+impl_writeable_tlv_based!(SharedOwnedOutput, {
+	(1, tx_out, required),
+	(3, local_owned, required),
+});
+
 impl SharedOwnedOutput {
 	pub fn new(tx_out: TxOut, local_owned: u64) -> SharedOwnedOutput {
 		debug_assert!(
@@ -1205,6 +1250,11 @@ pub(super) enum OutputOwned {
 	Shared(SharedOwnedOutput),
 }
 
+impl_writeable_tlv_based_enum!(OutputOwned,
+	{1, Single} => (),
+	{3, Shared} => (),
+);
+
 impl OutputOwned {
 	pub fn tx_out(&self) -> &TxOut {
 		match self {
@@ -1259,6 +1309,12 @@ pub(crate) struct InteractiveTxOutput {
 	output: OutputOwned,
 }
 
+impl_writeable_tlv_based!(InteractiveTxOutput, {
+	(1, serial_id, required),
+	(3, added_by, required),
+	(5, output, required),
+});
+
 impl InteractiveTxOutput {
 	pub fn tx_out(&self) -> &TxOut {
 		self.output.tx_out()

lightning/src/ln/msgs.rs

@@ -866,6 +866,18 @@ pub struct ChannelReestablish {
 	/// The sender's per-commitment point for their current commitment transaction
 	pub my_current_per_commitment_point: PublicKey,
 	/// The next funding transaction ID
+	///
+	/// Allows peers to finalize the signing steps of an interactive transaction construction, or
+	/// safely abort that transaction if it was not signed by one of the peers, who has thus already
+	/// removed it from its state.
+	///
+	/// If we've sent `commtiment_signed` for an interactively constructed transaction
+	/// during a signing session, but have not received `tx_signatures` we MUST set `next_funding_txid`
+	/// to the txid of that interactive transaction, else we MUST NOT set it.
+	///
+	/// See the spec for further details on this:
+	///   * `channel_reestablish`-sending node: https:///github.com/lightning/bolts/blob/247e83d/02-peer-protocol.md?plain=1#L2466-L2470
+	///   * `channel_reestablish`-receiving node: https:///github.com/lightning/bolts/blob/247e83d/02-peer-protocol.md?plain=1#L2520-L2531
 	pub next_funding_txid: Option<Txid>,
 }
 

lightning/src/util/config.rs

@@ -875,6 +875,10 @@ pub struct UserConfig {
 	/// [`ChannelManager::send_payment_for_bolt12_invoice`]: crate::ln::channelmanager::ChannelManager::send_payment_for_bolt12_invoice
 	/// [`ChannelManager::abandon_payment`]: crate::ln::channelmanager::ChannelManager::abandon_payment
 	pub manually_handle_bolt12_invoices: bool,
+	/// If this is set to `true`, dual-funded channels will be enabled.
+	///
+	/// Default value: `false`
+	pub enable_dual_funded_channels: bool,
 }
 
 impl Default for UserConfig {
@@ -888,6 +892,7 @@ impl Default for UserConfig {
 			manually_accept_inbound_channels: false,
 			accept_intercept_htlcs: false,
 			manually_handle_bolt12_invoices: false,
+			enable_dual_funded_channels: false,
 		}
 	}
 }
@@ -907,6 +912,7 @@ impl Readable for UserConfig {
 			manually_accept_inbound_channels: Readable::read(reader)?,
 			accept_intercept_htlcs: Readable::read(reader)?,
 			manually_handle_bolt12_invoices: Readable::read(reader)?,
+			enable_dual_funded_channels: Readable::read(reader)?,
 		})
 	}
 }