Combine InboundV2Channel and OutboundV2Channel

Pending v2 channels will need to be broken up into separate phases for
constructing and signing the funding transaction. To avoid increasing
the number of phases, combine the InboundV2Channel and OutboundV2Channel
types so that the can be used in one phase. Whether the channel is
inbound or outbound can be inferred from the ChannelContext.

Author: jkczyz

lightning/src/ln/channel.rs

@@ -1127,9 +1127,9 @@ pub(super) enum ChannelPhase<SP: Deref> where SP::Target: SignerProvider {
 	UnfundedOutboundV1(OutboundV1Channel<SP>),
 	UnfundedInboundV1(InboundV1Channel<SP>),
 	#[allow(dead_code)] // TODO(dual_funding): Remove once creating V2 channels is enabled.
-	UnfundedOutboundV2(OutboundV2Channel<SP>),
+	UnfundedOutboundV2(PendingV2Channel<SP>),
 	#[allow(dead_code)] // TODO(dual_funding): Remove once accepting V2 channels is enabled.
-	UnfundedInboundV2(InboundV2Channel<SP>),
+	UnfundedInboundV2(PendingV2Channel<SP>),
 	Funded(Channel<SP>),
 }
 
@@ -1849,25 +1849,7 @@ pub(super) trait InteractivelyFunded<SP: Deref> where SP::Target: SignerProvider
 	}
 }
 
-impl<SP: Deref> InteractivelyFunded<SP> for OutboundV2Channel<SP> where SP::Target: SignerProvider {
-	fn context(&self) -> &ChannelContext<SP> {
-		&self.context
-	}
-	fn context_mut(&mut self) -> &mut ChannelContext<SP> {
-		&mut self.context
-	}
-	fn dual_funding_context(&self) -> &DualFundingChannelContext {
-		&self.dual_funding_context
-	}
-	fn unfunded_context(&self) -> &UnfundedChannelContext {
-		&self.unfunded_context
-	}
-	fn interactive_tx_constructor_mut(&mut self) -> &mut Option<InteractiveTxConstructor> {
-		&mut self.interactive_tx_constructor
-	}
-}
-
-impl<SP: Deref> InteractivelyFunded<SP> for InboundV2Channel<SP> where SP::Target: SignerProvider {
+impl<SP: Deref> InteractivelyFunded<SP> for PendingV2Channel<SP> where SP::Target: SignerProvider {
 	fn context(&self) -> &ChannelContext<SP> {
 		&self.context
 	}
@@ -8822,24 +8804,24 @@ impl<SP: Deref> InboundV1Channel<SP> where SP::Target: SignerProvider {
 	}
 }
 
-// A not-yet-funded outbound (from holder) channel using V2 channel establishment.
-pub(super) struct OutboundV2Channel<SP: Deref> where SP::Target: SignerProvider {
+// A not-yet-funded channel using V2 channel establishment.
+pub(super) struct PendingV2Channel<SP: Deref> where SP::Target: SignerProvider {
 	pub context: ChannelContext<SP>,
 	pub unfunded_context: UnfundedChannelContext,
 	pub dual_funding_context: DualFundingChannelContext,
 	/// The current interactive transaction construction session under negotiation.
 	interactive_tx_constructor: Option<InteractiveTxConstructor>,
 }
 
-impl<SP: Deref> OutboundV2Channel<SP> where SP::Target: SignerProvider {
+impl<SP: Deref> PendingV2Channel<SP> where SP::Target: SignerProvider {
 	#[allow(dead_code)] // TODO(dual_funding): Remove once creating V2 channels is enabled.
-	pub fn new<ES: Deref, F: Deref, L: Deref>(
+	pub fn new_outbound<ES: Deref, F: Deref, L: Deref>(
 		fee_estimator: &LowerBoundedFeeEstimator<F>, entropy_source: &ES, signer_provider: &SP,
 		counterparty_node_id: PublicKey, their_features: &InitFeatures, funding_satoshis: u64,
 		funding_inputs: Vec<(TxIn, TransactionU16LenLimited)>, user_id: u128, config: &UserConfig,
 		current_chain_height: u32, outbound_scid_alias: u64, funding_confirmation_target: ConfirmationTarget,
 		logger: L,
-	) -> Result<OutboundV2Channel<SP>, APIError>
+	) -> Result<Self, APIError>
 	where ES::Target: EntropySource,
 	      F::Target: FeeEstimator,
 	      L::Target: Logger,
@@ -8911,6 +8893,10 @@ impl<SP: Deref> OutboundV2Channel<SP> where SP::Target: SignerProvider {
 	}
 
 	pub fn get_open_channel_v2(&self, chain_hash: ChainHash) -> msgs::OpenChannelV2 {
+		if !self.context.is_outbound() {
+			debug_assert!(false, "Tried to send open_channel2 for an inbound channel?");
+		}
+
 		if self.context.have_received_message() {
 			debug_assert!(false, "Cannot generate an open_channel2 after we've moved forward");
 		}
@@ -8960,40 +8946,16 @@ impl<SP: Deref> OutboundV2Channel<SP> where SP::Target: SignerProvider {
 		}
 	}
 
-	pub fn into_channel(self, signing_session: InteractiveTxSigningSession) -> Result<Channel<SP>, ChannelError>{
-		let holder_commitment_point = self.unfunded_context.holder_commitment_point.ok_or(ChannelError::close(
-			format!("Expected to have holder commitment points available upon finishing interactive tx construction for channel {}",
-			self.context.channel_id())))?;
-		let channel = Channel {
-			context: self.context,
-			interactive_tx_signing_session: Some(signing_session),
-			holder_commitment_point,
-		};
-
-		Ok(channel)
-	}
-}
-
-// A not-yet-funded inbound (from counterparty) channel using V2 channel establishment.
-pub(super) struct InboundV2Channel<SP: Deref> where SP::Target: SignerProvider {
-	pub context: ChannelContext<SP>,
-	pub unfunded_context: UnfundedChannelContext,
-	pub dual_funding_context: DualFundingChannelContext,
-	/// The current interactive transaction construction session under negotiation.
-	interactive_tx_constructor: Option<InteractiveTxConstructor>,
-}
-
-impl<SP: Deref> InboundV2Channel<SP> where SP::Target: SignerProvider {
 	/// Creates a new dual-funded channel from a remote side's request for one.
 	/// Assumes chain_hash has already been checked and corresponds with what we expect!
 	#[allow(dead_code)] // TODO(dual_funding): Remove once V2 channels is enabled.
-	pub fn new<ES: Deref, F: Deref, L: Deref>(
+	pub fn new_inbound<ES: Deref, F: Deref, L: Deref>(
 		fee_estimator: &LowerBoundedFeeEstimator<F>, entropy_source: &ES, signer_provider: &SP,
 		holder_node_id: PublicKey, counterparty_node_id: PublicKey, our_supported_features: &ChannelTypeFeatures,
 		their_features: &InitFeatures, msg: &msgs::OpenChannelV2,
 		funding_inputs: Vec<(TxIn, TransactionU16LenLimited)>, total_witness_weight: Weight,
 		user_id: u128, config: &UserConfig, current_chain_height: u32, logger: &L,
-	) -> Result<InboundV2Channel<SP>, ChannelError>
+	) -> Result<Self, ChannelError>
 		where ES::Target: EntropySource,
 			  F::Target: FeeEstimator,
 			  L::Target: Logger,

lightning/src/ln/channelmanager.rs

@@ -50,7 +50,7 @@ use crate::ln::types::ChannelId;
 use crate::types::payment::{PaymentHash, PaymentPreimage, PaymentSecret};
 use crate::ln::channel::{self, Channel, ChannelPhase, ChannelError, ChannelUpdateStatus, ShutdownResult, UpdateFulfillCommitFetch, OutboundV1Channel, InboundV1Channel, WithChannelContext, InteractivelyFunded as _};
 #[cfg(any(dual_funding, splicing))]
-use crate::ln::channel::InboundV2Channel;
+use crate::ln::channel::PendingV2Channel;
 use crate::ln::channel_state::ChannelDetails;
 use crate::types::features::{Bolt12InvoiceFeatures, ChannelFeatures, ChannelTypeFeatures, InitFeatures, NodeFeatures};
 #[cfg(any(feature = "_test_utils", test))]
@@ -7702,10 +7702,13 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
 					},
 					#[cfg(dual_funding)]
 					OpenChannelMessage::V2(open_channel_msg) => {
-						InboundV2Channel::new(&self.fee_estimator, &self.entropy_source, &self.signer_provider,
-							self.get_our_node_id(), *counterparty_node_id, &self.channel_type_features(), &peer_state.latest_features,
-							&open_channel_msg, _funding_inputs, _total_witness_weight, user_channel_id,
-							&self.default_configuration, best_block_height, &self.logger
+						PendingV2Channel::new_inbound(
+							&self.fee_estimator, &self.entropy_source, &self.signer_provider,
+							self.get_our_node_id(), *counterparty_node_id,
+							&self.channel_type_features(), &peer_state.latest_features,
+							&open_channel_msg, _funding_inputs, _total_witness_weight,
+							user_channel_id, &self.default_configuration, best_block_height,
+							&self.logger,
 						).map_err(|_| MsgHandleErrInternal::from_chan_no_close(
 							ChannelError::Close(
 								(
@@ -7983,10 +7986,11 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
 			},
 			#[cfg(dual_funding)]
 			OpenChannelMessageRef::V2(msg) => {
-				let channel = InboundV2Channel::new(&self.fee_estimator, &self.entropy_source,
-					&self.signer_provider, self.get_our_node_id(), *counterparty_node_id,
-					&self.channel_type_features(), &peer_state.latest_features, msg, vec![], Weight::from_wu(0),
-					user_channel_id, &self.default_configuration, best_block_height, &self.logger
+				let channel = PendingV2Channel::new_inbound(
+					&self.fee_estimator, &self.entropy_source, &self.signer_provider,
+					self.get_our_node_id(), *counterparty_node_id, &self.channel_type_features(),
+					&peer_state.latest_features, msg, vec![], Weight::from_wu(0), user_channel_id,
+					&self.default_configuration, best_block_height, &self.logger,
 				).map_err(|e| MsgHandleErrInternal::from_chan_no_close(e, msg.common_fields.temporary_channel_id))?;
 				let message_send_event = events::MessageSendEvent::SendAcceptChannelV2 {
 					node_id: *counterparty_node_id,

lightning/src/ln/dual_funding_tests.rs

@@ -18,7 +18,7 @@ use {
 		CounterpartyChannelTransactionParameters,
 	},
 	crate::ln::channel::{
-		calculate_our_funding_satoshis, OutboundV2Channel, MIN_CHAN_DUST_LIMIT_SATOSHIS,
+		calculate_our_funding_satoshis, PendingV2Channel, MIN_CHAN_DUST_LIMIT_SATOSHIS,
 	},
 	crate::ln::channel_keys::{DelayedPaymentBasepoint, HtlcBasepoint, RevocationBasepoint},
 	crate::ln::functional_test_utils::*,
@@ -71,7 +71,7 @@ fn do_test_v2_channel_establishment(
 		MIN_CHAN_DUST_LIMIT_SATOSHIS,
 	)
 	.unwrap();
-	let mut channel = OutboundV2Channel::new(
+	let mut channel = PendingV2Channel::new_outbound(
 		&LowerBoundedFeeEstimator(node_cfgs[0].fee_estimator),
 		&nodes[0].node.entropy_source,
 		&nodes[0].node.signer_provider,