Contribute funding inputs on accepting dual-funded channel

lightning/src/ln/channel.rs

@@ -6314,6 +6314,19 @@ where
  }
 	}
 
+	#[cfg(all(test))]
+	pub fn get_initial_counterparty_commitment_signatures_for_test<L: Deref>(
+ &mut self, funding: &mut FundingScope, logger: &L,
+ counterparty_next_commitment_point_override: PublicKey,
+	) -> Option<(Signature, Vec<Signature>)>
+	where
+ SP::Target: SignerProvider,
+ L::Target: Logger,
+	{
+ self.counterparty_next_commitment_point = Some(counterparty_next_commitment_point_override);
+ self.get_initial_counterparty_commitment_signatures(funding, logger)
+	}
+
 	fn check_funding_meets_minimum_depth(&self, funding: &FundingScope, height: u32) -> bool {
  let minimum_depth = self
  .minimum_depth(funding)
@@ -13946,7 +13959,9 @@ where
 	pub funding: FundingScope,
 	pub context: ChannelContext<SP>,
 	pub unfunded_context: UnfundedChannelContext,
-	pub funding_negotiation_context: FundingNegotiationContext,
+	funding_tx_locktime: LockTime,
+	#[allow(unused)] // TODO(dual_funding): Remove once initiating V2 channels is enabled.
+	pub funding_negotiation_context: Option<FundingNegotiationContext>,
 	/// The current interactive transaction construction session under negotiation.
 	pub interactive_tx_constructor: Option<InteractiveTxConstructor>,
 }
@@ -14021,7 +14036,8 @@ where
  funding,
  context,
  unfunded_context,
- funding_negotiation_context,
+ funding_tx_locktime,
+ funding_negotiation_context: Some(funding_negotiation_context),
  interactive_tx_constructor: None,
  };
  Ok(chan)
@@ -14096,29 +14112,28 @@ where
  },
  funding_feerate_sat_per_1000_weight: self.context.feerate_per_kw,
  second_per_commitment_point,
- locktime: self.funding_negotiation_context.funding_tx_locktime.to_consensus_u32(),
+ locktime: self.funding_tx_locktime.to_consensus_u32(),
  require_confirmed_inputs: None,
  }
 	}
 
 	/// 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!
-	/// TODO(dual_funding): Allow contributions, pass intended amount and inputs
 	#[allow(dead_code)] // TODO(dual_funding): Remove once V2 channels is enabled.
 	#[rustfmt::skip]
 	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,
- user_id: u128, config: &UserConfig, current_chain_height: u32, logger: &L,
+ their_features: &InitFeatures, msg: &msgs::OpenChannelV2, user_id: u128, config: &UserConfig,
+ current_chain_height: u32, logger: &L, our_funding_contribution: Amount,
+ our_funding_inputs: Vec<FundingTxInput>, change_script: Option<ScriptBuf>,
 	) -> Result<Self, ChannelError>
  where ES::Target: EntropySource,
  F::Target: FeeEstimator,
  L::Target: Logger,
 	{
- // TODO(dual_funding): Take these as input once supported
- let (our_funding_contribution, our_funding_contribution_sats) = (SignedAmount::ZERO, 0u64);
- let our_funding_inputs = Vec::new();
+ debug_assert!(our_funding_contribution <= Amount::MAX_MONEY);
+ let our_funding_contribution_sats = our_funding_contribution.to_sat();
 
  let channel_value_satoshis =
  our_funding_contribution_sats.saturating_add(msg.common_fields.funding_satoshis);
@@ -14161,39 +14176,33 @@ where
  &funding.get_counterparty_pubkeys().revocation_basepoint);
  context.channel_id = channel_id;
 
+ let funding_tx_locktime = LockTime::from_consensus(msg.locktime);
  let funding_negotiation_context = FundingNegotiationContext {
  is_initiator: false,
- our_funding_contribution,
- funding_tx_locktime: LockTime::from_consensus(msg.locktime),
+ our_funding_contribution: our_funding_contribution
+ .to_signed()
+ .expect("our_funding_contribution should not be greater than Amount::MAX_MONEY"),
+ funding_tx_locktime,
  funding_feerate_sat_per_1000_weight: msg.funding_feerate_sat_per_1000_weight,
  shared_funding_input: None,
  our_funding_inputs: our_funding_inputs.clone(),
  our_funding_outputs: Vec::new(),
- change_script: None,
- };
- let shared_funding_output = TxOut {
- value: Amount::from_sat(funding.get_value_satoshis()),
- script_pubkey: funding.get_funding_redeemscript().to_p2wsh(),
+ change_script,
  };
 
- let interactive_tx_constructor = Some(InteractiveTxConstructor::new(
- InteractiveTxConstructorArgs {
+ let mut interactive_tx_constructor = funding_negotiation_context
+ .into_interactive_tx_constructor(
+ &context,
+ &funding,
+ signer_provider,
  entropy_source,
  holder_node_id,
- counterparty_node_id,
- channel_id: context.channel_id,
- feerate_sat_per_kw: funding_negotiation_context.funding_feerate_sat_per_1000_weight,
- funding_tx_locktime: funding_negotiation_context.funding_tx_locktime,
- is_initiator: false,
- inputs_to_contribute: our_funding_inputs,
- shared_funding_input: None,
- shared_funding_output: SharedOwnedOutput::new(shared_funding_output, our_funding_contribution_sats),
- outputs_to_contribute: funding_negotiation_context.our_funding_outputs.clone(),
- }
- ).map_err(|err| {
- let reason = ClosureReason::ProcessingError { err: err.reason.to_string() };
- ChannelError::Close((err.reason.to_string(), reason))
- })?);
+ )
+ .map_err(|err| {
+ let reason = ClosureReason::ProcessingError { err: err.reason.to_string() };
+ ChannelError::Close((err.reason.to_string(), reason))
+ })?;
+ debug_assert!(interactive_tx_constructor.take_initiator_first_message().is_none());
 
  let unfunded_context = UnfundedChannelContext {
  unfunded_channel_age_ticks: 0,
@@ -14202,9 +14211,10 @@ where
  Ok(Self {
  funding,
  context,
- funding_negotiation_context,
- interactive_tx_constructor,
  unfunded_context,
+ funding_tx_locktime,
+ funding_negotiation_context: None,
+ interactive_tx_constructor: Some(interactive_tx_constructor),
  })
 	}
 
@@ -14267,8 +14277,7 @@ where
  }),
  channel_type: Some(self.funding.get_channel_type().clone()),
  },
- funding_satoshis: self.funding_negotiation_context.our_funding_contribution.to_sat()
- as u64,
+ funding_satoshis: self.our_funding_contribution().to_sat(),
  second_per_commitment_point,
  require_confirmed_inputs: None,
  }
@@ -14283,6 +14292,10 @@ where
 	pub fn get_accept_channel_v2_message(&self) -> msgs::AcceptChannelV2 {
  self.generate_accept_channel_v2_message()
 	}
+
+	pub fn our_funding_contribution(&self) -> Amount {
+ Amount::from_sat(self.funding.value_to_self_msat / 1000)
+	}
 }
 
 // Unfunded channel utilities

lightning/src/ln/channelmanager.rs

@@ -30,7 +30,7 @@ use bitcoin::hashes::{Hash, HashEngine, HmacEngine};
 
 use bitcoin::secp256k1::Secp256k1;
 use bitcoin::secp256k1::{PublicKey, SecretKey};
-use bitcoin::{secp256k1, Sequence, SignedAmount};
+use bitcoin::{secp256k1, Amount, ScriptBuf, Sequence};
 
 use crate::blinded_path::message::{
 	AsyncPaymentsContext, BlindedMessagePath, MessageForwardNode, OffersContext,
@@ -65,7 +65,7 @@ use crate::ln::channel::{
 	WithChannelContext,
 };
 use crate::ln::channel_state::ChannelDetails;
-use crate::ln::funding::SpliceContribution;
+use crate::ln::funding::{FundingTxInput, SpliceContribution};
 use crate::ln::inbound_payment;
 use crate::ln::interactivetxs::InteractiveTxMessageSend;
 use crate::ln::msgs;
@@ -9814,6 +9814,9 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
  false,
  user_channel_id,
  config_overrides,
+ Amount::ZERO,
+ vec![],
+ None,
  )
 	}
 
@@ -9845,15 +9848,73 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
  true,
  user_channel_id,
  config_overrides,
+ Amount::ZERO,
+ vec![],
+ None,
+ )
+	}
+
+	/// Accepts a request to open a dual-funded channel with a contribution provided after an
+	/// [`Event::OpenChannelRequest`].
+	///
+	/// The [`Event::OpenChannelRequest::channel_negotiation_type`] field will indicate the open channel
+	/// request is for a dual-funded channel when the variant is [`InboundChannelFunds::DualFunded`].
+	///
+	/// The `temporary_channel_id` parameter indicates which inbound channel should be accepted,
+	/// and the `counterparty_node_id` parameter is the id of the peer that has requested to open
+	/// the channel.
+	///
+	/// The `user_channel_id` parameter will be provided back in
+	/// [`Event::ChannelClosed::user_channel_id`] to allow tracking of which events correspond
+	/// with which `accept_inbound_channel_*` call.
+	///
+	/// The `funding_inputs` parameter provides which UTXOs to use for `our_funding_contribution`
+	/// along with the corresponding satisfaction weight. They must be able to cover any fees needed
+	/// to pay for the contributed weight to the funding transaction. This includes the witnesses
+	/// provided through calling [`ChannelManager::funding_transaction_signed`] after receiving
+	/// [`Event::FundingTransactionReadyForSigning`].
+	///
+	/// Note that this method will return an error and reject the channel if it requires support for
+	/// zero confirmations.
+	// TODO(dual_funding): Discussion on complications with 0conf dual-funded channels where "locking"
+	// of UTXOs used for funding would be required and other issues.
+	// See https://diyhpl.us/~bryan/irc/bitcoin/bitcoin-dev/linuxfoundation-pipermail/lightning-dev/2023-May/003922.txt
+	///
+	/// [`Event::OpenChannelRequest`]: events::Event::OpenChannelRequest
+	/// [`Event::OpenChannelRequest::channel_negotiation_type`]: events::Event::OpenChannelRequest::channel_negotiation_type
+	/// [`Event::ChannelClosed::user_channel_id`]: events::Event::ChannelClosed::user_channel_id
+	/// [`Event::FundingTransactionReadyForSigning`]: events::Event::FundingTransactionReadyForSigning
+	/// [`ChannelManager::funding_transaction_signed`]: ChannelManager::funding_transaction_signed
+	pub fn accept_inbound_channel_with_contribution(
+ &self, temporary_channel_id: &ChannelId, counterparty_node_id: &PublicKey,
+ user_channel_id: u128, config_overrides: Option<ChannelConfigOverrides>,
+ our_funding_contribution: Amount, funding_inputs: Vec<FundingTxInput>,
+ change_script: Option<ScriptBuf>,
+	) -> Result<(), APIError> {
+ self.do_accept_inbound_channel(
+ temporary_channel_id,
+ counterparty_node_id,
+ false,
+ user_channel_id,
+ config_overrides,
+ our_funding_contribution,
+ funding_inputs,
+ change_script,
  )
 	}
 
-	/// TODO(dual_funding): Allow contributions, pass intended amount and inputs
 	#[rustfmt::skip]
 	fn do_accept_inbound_channel(
- &self, temporary_channel_id: &ChannelId, counterparty_node_id: &PublicKey, accept_0conf: bool,
- user_channel_id: u128, config_overrides: Option<ChannelConfigOverrides>
+ &self, temporary_channel_id: &ChannelId, counterparty_node_id: &PublicKey,
+ accept_0conf: bool, user_channel_id: u128, config_overrides: Option<ChannelConfigOverrides>,
+ our_funding_contribution: Amount, funding_inputs: Vec<FundingTxInput>,
+ change_script: Option<ScriptBuf>,
 	) -> Result<(), APIError> {
+ if our_funding_contribution > Amount::MAX_MONEY {
+ return Err(APIError::APIMisuseError {
+ err: format!("the funding contribution must be smaller than the total bitcoin supply, it was {}", our_funding_contribution)
+ });
+ }
 
  let mut config = self.config.read().unwrap().clone();
 
@@ -9911,7 +9972,7 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
  &self.channel_type_features(), &peer_state.latest_features,
  &open_channel_msg,
  user_channel_id, &config, best_block_height,
- &self.logger,
+ &self.logger, our_funding_contribution, funding_inputs, change_script,
  ).map_err(|e| {
  let channel_id = open_channel_msg.common_fields.temporary_channel_id;
  MsgHandleErrInternal::from_chan_no_close(e, channel_id)
@@ -10055,7 +10116,7 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
 
  // Inbound V2 channels with contributed inputs are not considered unfunded.
  if let Some(unfunded_chan) = chan.as_unfunded_v2() {
- if unfunded_chan.funding_negotiation_context.our_funding_contribution > SignedAmount::ZERO {
+ if unfunded_chan.our_funding_contribution() > Amount::ZERO {
  continue;
  }
  }
@@ -10197,7 +10258,7 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
  &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, user_channel_id,
- &self.config.read().unwrap(), best_block_height, &self.logger,
+ &self.config.read().unwrap(), best_block_height, &self.logger, Amount::ZERO, vec![], None,
  ).map_err(|e| MsgHandleErrInternal::from_chan_no_close(e, msg.common_fields.temporary_channel_id))?;
  let message_send_event = MessageSendEvent::SendAcceptChannelV2 {
  node_id: *counterparty_node_id,

lightning/src/ln/channel.rs

@@ -6314,6 +6314,19 @@ where
  }
 	}
 
+	#[cfg(all(test))]
+	pub fn get_initial_counterparty_commitment_signatures_for_test<L: Deref>(
+ &mut self, funding: &mut FundingScope, logger: &L,
+ counterparty_next_commitment_point_override: PublicKey,
+	) -> Option<(Signature, Vec<Signature>)>
+	where
+ SP::Target: SignerProvider,
+ L::Target: Logger,
+	{
+ self.counterparty_next_commitment_point = Some(counterparty_next_commitment_point_override);
+ self.get_initial_counterparty_commitment_signatures(funding, logger)
+	}
+
 	fn check_funding_meets_minimum_depth(&self, funding: &FundingScope, height: u32) -> bool {
  let minimum_depth = self
  .minimum_depth(funding)
@@ -13946,7 +13959,9 @@ where
 	pub funding: FundingScope,
 	pub context: ChannelContext<SP>,
 	pub unfunded_context: UnfundedChannelContext,
-	pub funding_negotiation_context: FundingNegotiationContext,
+	funding_tx_locktime: LockTime,
+	#[allow(unused)] // TODO(dual_funding): Remove once initiating V2 channels is enabled.
+	pub funding_negotiation_context: Option<FundingNegotiationContext>,
 	/// The current interactive transaction construction session under negotiation.
 	pub interactive_tx_constructor: Option<InteractiveTxConstructor>,
 }
@@ -14021,7 +14036,8 @@ where
  funding,
  context,
  unfunded_context,
- funding_negotiation_context,
+ funding_tx_locktime,
+ funding_negotiation_context: Some(funding_negotiation_context),
  interactive_tx_constructor: None,
  };
  Ok(chan)
@@ -14096,29 +14112,28 @@ where
  },
  funding_feerate_sat_per_1000_weight: self.context.feerate_per_kw,
  second_per_commitment_point,
- locktime: self.funding_negotiation_context.funding_tx_locktime.to_consensus_u32(),
+ locktime: self.funding_tx_locktime.to_consensus_u32(),
  require_confirmed_inputs: None,
  }
 	}
 
 	/// 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!
-	/// TODO(dual_funding): Allow contributions, pass intended amount and inputs
 	#[allow(dead_code)] // TODO(dual_funding): Remove once V2 channels is enabled.
 	#[rustfmt::skip]
 	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,
- user_id: u128, config: &UserConfig, current_chain_height: u32, logger: &L,
+ their_features: &InitFeatures, msg: &msgs::OpenChannelV2, user_id: u128, config: &UserConfig,
+ current_chain_height: u32, logger: &L, our_funding_contribution: Amount,
+ our_funding_inputs: Vec<FundingTxInput>, change_script: Option<ScriptBuf>,
 	) -> Result<Self, ChannelError>
  where ES::Target: EntropySource,
  F::Target: FeeEstimator,
  L::Target: Logger,
 	{
- // TODO(dual_funding): Take these as input once supported
- let (our_funding_contribution, our_funding_contribution_sats) = (SignedAmount::ZERO, 0u64);
- let our_funding_inputs = Vec::new();
+ debug_assert!(our_funding_contribution <= Amount::MAX_MONEY);
+ let our_funding_contribution_sats = our_funding_contribution.to_sat();
 
  let channel_value_satoshis =
  our_funding_contribution_sats.saturating_add(msg.common_fields.funding_satoshis);
@@ -14161,39 +14176,33 @@ where
  &funding.get_counterparty_pubkeys().revocation_basepoint);
  context.channel_id = channel_id;
 
+ let funding_tx_locktime = LockTime::from_consensus(msg.locktime);
  let funding_negotiation_context = FundingNegotiationContext {
  is_initiator: false,
- our_funding_contribution,
- funding_tx_locktime: LockTime::from_consensus(msg.locktime),
+ our_funding_contribution: our_funding_contribution
+ .to_signed()
+ .expect("our_funding_contribution should not be greater than Amount::MAX_MONEY"),
+ funding_tx_locktime,
  funding_feerate_sat_per_1000_weight: msg.funding_feerate_sat_per_1000_weight,
  shared_funding_input: None,
  our_funding_inputs: our_funding_inputs.clone(),
  our_funding_outputs: Vec::new(),
- change_script: None,
- };
- let shared_funding_output = TxOut {
- value: Amount::from_sat(funding.get_value_satoshis()),
- script_pubkey: funding.get_funding_redeemscript().to_p2wsh(),
+ change_script,
  };
 
- let interactive_tx_constructor = Some(InteractiveTxConstructor::new(
- InteractiveTxConstructorArgs {
+ let mut interactive_tx_constructor = funding_negotiation_context
+ .into_interactive_tx_constructor(
+ &context,
+ &funding,
+ signer_provider,
  entropy_source,
  holder_node_id,
- counterparty_node_id,
- channel_id: context.channel_id,
- feerate_sat_per_kw: funding_negotiation_context.funding_feerate_sat_per_1000_weight,
- funding_tx_locktime: funding_negotiation_context.funding_tx_locktime,
- is_initiator: false,
- inputs_to_contribute: our_funding_inputs,
- shared_funding_input: None,
- shared_funding_output: SharedOwnedOutput::new(shared_funding_output, our_funding_contribution_sats),
- outputs_to_contribute: funding_negotiation_context.our_funding_outputs.clone(),
- }
- ).map_err(|err| {
- let reason = ClosureReason::ProcessingError { err: err.reason.to_string() };
- ChannelError::Close((err.reason.to_string(), reason))
- })?);
+ )
+ .map_err(|err| {
+ let reason = ClosureReason::ProcessingError { err: err.reason.to_string() };
+ ChannelError::Close((err.reason.to_string(), reason))
+ })?;
+ debug_assert!(interactive_tx_constructor.take_initiator_first_message().is_none());
 
  let unfunded_context = UnfundedChannelContext {
  unfunded_channel_age_ticks: 0,
@@ -14202,9 +14211,10 @@ where
  Ok(Self {
  funding,
  context,
- funding_negotiation_context,
- interactive_tx_constructor,
  unfunded_context,
+ funding_tx_locktime,
+ funding_negotiation_context: None,
+ interactive_tx_constructor: Some(interactive_tx_constructor),
  })
 	}
 
@@ -14267,8 +14277,7 @@ where
  }),
  channel_type: Some(self.funding.get_channel_type().clone()),
  },
- funding_satoshis: self.funding_negotiation_context.our_funding_contribution.to_sat()
- as u64,
+ funding_satoshis: self.our_funding_contribution().to_sat(),
  second_per_commitment_point,
  require_confirmed_inputs: None,
  }
@@ -14283,6 +14292,10 @@ where
 	pub fn get_accept_channel_v2_message(&self) -> msgs::AcceptChannelV2 {
  self.generate_accept_channel_v2_message()
 	}
+
+	pub fn our_funding_contribution(&self) -> Amount {
+ Amount::from_sat(self.funding.value_to_self_msat / 1000)
+	}
 }
 
 // Unfunded channel utilities

lightning/src/ln/channelmanager.rs

@@ -30,7 +30,7 @@ use bitcoin::hashes::{Hash, HashEngine, HmacEngine};
 
 use bitcoin::secp256k1::Secp256k1;
 use bitcoin::secp256k1::{PublicKey, SecretKey};
-use bitcoin::{secp256k1, Sequence, SignedAmount};
+use bitcoin::{secp256k1, Amount, ScriptBuf, Sequence};
 
 use crate::blinded_path::message::{
 	AsyncPaymentsContext, BlindedMessagePath, MessageForwardNode, OffersContext,
@@ -65,7 +65,7 @@ use crate::ln::channel::{
 	WithChannelContext,
 };
 use crate::ln::channel_state::ChannelDetails;
-use crate::ln::funding::SpliceContribution;
+use crate::ln::funding::{FundingTxInput, SpliceContribution};
 use crate::ln::inbound_payment;
 use crate::ln::interactivetxs::InteractiveTxMessageSend;
 use crate::ln::msgs;
@@ -9814,6 +9814,9 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
  false,
  user_channel_id,
  config_overrides,
+ Amount::ZERO,
+ vec![],
+ None,
  )
 	}
 
@@ -9845,15 +9848,73 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
  true,
  user_channel_id,
  config_overrides,
+ Amount::ZERO,
+ vec![],
+ None,
+ )
+	}
+
+	/// Accepts a request to open a dual-funded channel with a contribution provided after an
+	/// [`Event::OpenChannelRequest`].
+	///
+	/// The [`Event::OpenChannelRequest::channel_negotiation_type`] field will indicate the open channel
+	/// request is for a dual-funded channel when the variant is [`InboundChannelFunds::DualFunded`].
+	///
+	/// The `temporary_channel_id` parameter indicates which inbound channel should be accepted,
+	/// and the `counterparty_node_id` parameter is the id of the peer that has requested to open
+	/// the channel.
+	///
+	/// The `user_channel_id` parameter will be provided back in
+	/// [`Event::ChannelClosed::user_channel_id`] to allow tracking of which events correspond
+	/// with which `accept_inbound_channel_*` call.
+	///
+	/// The `funding_inputs` parameter provides which UTXOs to use for `our_funding_contribution`
+	/// along with the corresponding satisfaction weight. They must be able to cover any fees needed
+	/// to pay for the contributed weight to the funding transaction. This includes the witnesses
+	/// provided through calling [`ChannelManager::funding_transaction_signed`] after receiving
+	/// [`Event::FundingTransactionReadyForSigning`].
+	///
+	/// Note that this method will return an error and reject the channel if it requires support for
+	/// zero confirmations.
+	// TODO(dual_funding): Discussion on complications with 0conf dual-funded channels where "locking"
+	// of UTXOs used for funding would be required and other issues.
+	// See https://diyhpl.us/~bryan/irc/bitcoin/bitcoin-dev/linuxfoundation-pipermail/lightning-dev/2023-May/003922.txt
+	///
+	/// [`Event::OpenChannelRequest`]: events::Event::OpenChannelRequest
+	/// [`Event::OpenChannelRequest::channel_negotiation_type`]: events::Event::OpenChannelRequest::channel_negotiation_type
+	/// [`Event::ChannelClosed::user_channel_id`]: events::Event::ChannelClosed::user_channel_id
+	/// [`Event::FundingTransactionReadyForSigning`]: events::Event::FundingTransactionReadyForSigning
+	/// [`ChannelManager::funding_transaction_signed`]: ChannelManager::funding_transaction_signed
+	pub fn accept_inbound_channel_with_contribution(
+ &self, temporary_channel_id: &ChannelId, counterparty_node_id: &PublicKey,
+ user_channel_id: u128, config_overrides: Option<ChannelConfigOverrides>,
+ our_funding_contribution: Amount, funding_inputs: Vec<FundingTxInput>,
+ change_script: Option<ScriptBuf>,
+	) -> Result<(), APIError> {
+ self.do_accept_inbound_channel(
+ temporary_channel_id,
+ counterparty_node_id,
+ false,
+ user_channel_id,
+ config_overrides,
+ our_funding_contribution,
+ funding_inputs,
+ change_script,
  )
 	}
 
-	/// TODO(dual_funding): Allow contributions, pass intended amount and inputs
 	#[rustfmt::skip]
 	fn do_accept_inbound_channel(
- &self, temporary_channel_id: &ChannelId, counterparty_node_id: &PublicKey, accept_0conf: bool,
- user_channel_id: u128, config_overrides: Option<ChannelConfigOverrides>
+ &self, temporary_channel_id: &ChannelId, counterparty_node_id: &PublicKey,
+ accept_0conf: bool, user_channel_id: u128, config_overrides: Option<ChannelConfigOverrides>,
+ our_funding_contribution: Amount, funding_inputs: Vec<FundingTxInput>,
+ change_script: Option<ScriptBuf>,
 	) -> Result<(), APIError> {
+ if our_funding_contribution > Amount::MAX_MONEY {
+ return Err(APIError::APIMisuseError {
+ err: format!("the funding contribution must be smaller than the total bitcoin supply, it was {}", our_funding_contribution)
+ });
+ }
 
  let mut config = self.config.read().unwrap().clone();
 
@@ -9911,7 +9972,7 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
  &self.channel_type_features(), &peer_state.latest_features,
  &open_channel_msg,
  user_channel_id, &config, best_block_height,
- &self.logger,
+ &self.logger, our_funding_contribution, funding_inputs, change_script,
  ).map_err(|e| {
  let channel_id = open_channel_msg.common_fields.temporary_channel_id;
  MsgHandleErrInternal::from_chan_no_close(e, channel_id)
@@ -10055,7 +10116,7 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
 
  // Inbound V2 channels with contributed inputs are not considered unfunded.
  if let Some(unfunded_chan) = chan.as_unfunded_v2() {
- if unfunded_chan.funding_negotiation_context.our_funding_contribution > SignedAmount::ZERO {
+ if unfunded_chan.our_funding_contribution() > Amount::ZERO {
  continue;
  }
  }
@@ -10197,7 +10258,7 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
  &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, user_channel_id,
- &self.config.read().unwrap(), best_block_height, &self.logger,
+ &self.config.read().unwrap(), best_block_height, &self.logger, Amount::ZERO, vec![], None,
  ).map_err(|e| MsgHandleErrInternal::from_chan_no_close(e, msg.common_fields.temporary_channel_id))?;
  let message_send_event = MessageSendEvent::SendAcceptChannelV2 {
  node_id: *counterparty_node_id,

lightning/src/ln/channel.rs

@@ -6314,6 +6314,19 @@ where
  }
 	}
 
+	#[cfg(all(test))]
+	pub fn get_initial_counterparty_commitment_signatures_for_test<L: Deref>(
+ &mut self, funding: &mut FundingScope, logger: &L,
+ counterparty_next_commitment_point_override: PublicKey,
+	) -> Option<(Signature, Vec<Signature>)>
+	where
+ SP::Target: SignerProvider,
+ L::Target: Logger,
+	{
+ self.counterparty_next_commitment_point = Some(counterparty_next_commitment_point_override);
+ self.get_initial_counterparty_commitment_signatures(funding, logger)
+	}
+
 	fn check_funding_meets_minimum_depth(&self, funding: &FundingScope, height: u32) -> bool {
  let minimum_depth = self
  .minimum_depth(funding)
@@ -13946,7 +13959,9 @@ where
 	pub funding: FundingScope,
 	pub context: ChannelContext<SP>,
 	pub unfunded_context: UnfundedChannelContext,
-	pub funding_negotiation_context: FundingNegotiationContext,
+	funding_tx_locktime: LockTime,
+	#[allow(unused)] // TODO(dual_funding): Remove once initiating V2 channels is enabled.
+	pub funding_negotiation_context: Option<FundingNegotiationContext>,
 	/// The current interactive transaction construction session under negotiation.
 	pub interactive_tx_constructor: Option<InteractiveTxConstructor>,
 }
@@ -14021,7 +14036,8 @@ where
  funding,
  context,
  unfunded_context,
- funding_negotiation_context,
+ funding_tx_locktime,
+ funding_negotiation_context: Some(funding_negotiation_context),
  interactive_tx_constructor: None,
  };
  Ok(chan)
@@ -14096,29 +14112,28 @@ where
  },
  funding_feerate_sat_per_1000_weight: self.context.feerate_per_kw,
  second_per_commitment_point,
- locktime: self.funding_negotiation_context.funding_tx_locktime.to_consensus_u32(),
+ locktime: self.funding_tx_locktime.to_consensus_u32(),
  require_confirmed_inputs: None,
  }
 	}
 
 	/// 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!
-	/// TODO(dual_funding): Allow contributions, pass intended amount and inputs
 	#[allow(dead_code)] // TODO(dual_funding): Remove once V2 channels is enabled.
 	#[rustfmt::skip]
 	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,
- user_id: u128, config: &UserConfig, current_chain_height: u32, logger: &L,
+ their_features: &InitFeatures, msg: &msgs::OpenChannelV2, user_id: u128, config: &UserConfig,
+ current_chain_height: u32, logger: &L, our_funding_contribution: Amount,
+ our_funding_inputs: Vec<FundingTxInput>, change_script: Option<ScriptBuf>,
 	) -> Result<Self, ChannelError>
  where ES::Target: EntropySource,
  F::Target: FeeEstimator,
  L::Target: Logger,
 	{
- // TODO(dual_funding): Take these as input once supported
- let (our_funding_contribution, our_funding_contribution_sats) = (SignedAmount::ZERO, 0u64);
- let our_funding_inputs = Vec::new();
+ debug_assert!(our_funding_contribution <= Amount::MAX_MONEY);
+ let our_funding_contribution_sats = our_funding_contribution.to_sat();
 
  let channel_value_satoshis =
  our_funding_contribution_sats.saturating_add(msg.common_fields.funding_satoshis);
@@ -14161,39 +14176,33 @@ where
  &funding.get_counterparty_pubkeys().revocation_basepoint);
  context.channel_id = channel_id;
 
+ let funding_tx_locktime = LockTime::from_consensus(msg.locktime);
  let funding_negotiation_context = FundingNegotiationContext {
  is_initiator: false,
- our_funding_contribution,
- funding_tx_locktime: LockTime::from_consensus(msg.locktime),
+ our_funding_contribution: our_funding_contribution
+ .to_signed()
+ .expect("our_funding_contribution should not be greater than Amount::MAX_MONEY"),
+ funding_tx_locktime,
  funding_feerate_sat_per_1000_weight: msg.funding_feerate_sat_per_1000_weight,
  shared_funding_input: None,
  our_funding_inputs: our_funding_inputs.clone(),
  our_funding_outputs: Vec::new(),
- change_script: None,
- };
- let shared_funding_output = TxOut {
- value: Amount::from_sat(funding.get_value_satoshis()),
- script_pubkey: funding.get_funding_redeemscript().to_p2wsh(),
+ change_script,
  };
 
- let interactive_tx_constructor = Some(InteractiveTxConstructor::new(
- InteractiveTxConstructorArgs {
+ let mut interactive_tx_constructor = funding_negotiation_context
+ .into_interactive_tx_constructor(
+ &context,
+ &funding,
+ signer_provider,
  entropy_source,
  holder_node_id,
- counterparty_node_id,
- channel_id: context.channel_id,
- feerate_sat_per_kw: funding_negotiation_context.funding_feerate_sat_per_1000_weight,
- funding_tx_locktime: funding_negotiation_context.funding_tx_locktime,
- is_initiator: false,
- inputs_to_contribute: our_funding_inputs,
- shared_funding_input: None,
- shared_funding_output: SharedOwnedOutput::new(shared_funding_output, our_funding_contribution_sats),
- outputs_to_contribute: funding_negotiation_context.our_funding_outputs.clone(),
- }
- ).map_err(|err| {
- let reason = ClosureReason::ProcessingError { err: err.reason.to_string() };
- ChannelError::Close((err.reason.to_string(), reason))
- })?);
+ )
+ .map_err(|err| {
+ let reason = ClosureReason::ProcessingError { err: err.reason.to_string() };
+ ChannelError::Close((err.reason.to_string(), reason))
+ })?;
+ debug_assert!(interactive_tx_constructor.take_initiator_first_message().is_none());
 
  let unfunded_context = UnfundedChannelContext {
  unfunded_channel_age_ticks: 0,
@@ -14202,9 +14211,10 @@ where
  Ok(Self {
  funding,
  context,
- funding_negotiation_context,
- interactive_tx_constructor,
  unfunded_context,
+ funding_tx_locktime,
+ funding_negotiation_context: None,
+ interactive_tx_constructor: Some(interactive_tx_constructor),
  })
 	}
 
@@ -14267,8 +14277,7 @@ where
  }),
  channel_type: Some(self.funding.get_channel_type().clone()),
  },
- funding_satoshis: self.funding_negotiation_context.our_funding_contribution.to_sat()
- as u64,
+ funding_satoshis: self.our_funding_contribution().to_sat(),
  second_per_commitment_point,
  require_confirmed_inputs: None,
  }
@@ -14283,6 +14292,10 @@ where
 	pub fn get_accept_channel_v2_message(&self) -> msgs::AcceptChannelV2 {
  self.generate_accept_channel_v2_message()
 	}
+
+	pub fn our_funding_contribution(&self) -> Amount {
+ Amount::from_sat(self.funding.value_to_self_msat / 1000)
+	}
 }
 
 // Unfunded channel utilities

lightning/src/ln/channelmanager.rs

@@ -30,7 +30,7 @@ use bitcoin::hashes::{Hash, HashEngine, HmacEngine};
 
 use bitcoin::secp256k1::Secp256k1;
 use bitcoin::secp256k1::{PublicKey, SecretKey};
-use bitcoin::{secp256k1, Sequence, SignedAmount};
+use bitcoin::{secp256k1, Amount, ScriptBuf, Sequence};
 
 use crate::blinded_path::message::{
 	AsyncPaymentsContext, BlindedMessagePath, MessageForwardNode, OffersContext,
@@ -65,7 +65,7 @@ use crate::ln::channel::{
 	WithChannelContext,
 };
 use crate::ln::channel_state::ChannelDetails;
-use crate::ln::funding::SpliceContribution;
+use crate::ln::funding::{FundingTxInput, SpliceContribution};
 use crate::ln::inbound_payment;
 use crate::ln::interactivetxs::InteractiveTxMessageSend;
 use crate::ln::msgs;
@@ -9814,6 +9814,9 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
  false,
  user_channel_id,
  config_overrides,
+ Amount::ZERO,
+ vec![],
+ None,
  )
 	}
 
@@ -9845,15 +9848,73 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
  true,
  user_channel_id,
  config_overrides,
+ Amount::ZERO,
+ vec![],
+ None,
+ )
+	}
+
+	/// Accepts a request to open a dual-funded channel with a contribution provided after an
+	/// [`Event::OpenChannelRequest`].
+	///
+	/// The [`Event::OpenChannelRequest::channel_negotiation_type`] field will indicate the open channel
+	/// request is for a dual-funded channel when the variant is [`InboundChannelFunds::DualFunded`].
+	///
+	/// The `temporary_channel_id` parameter indicates which inbound channel should be accepted,
+	/// and the `counterparty_node_id` parameter is the id of the peer that has requested to open
+	/// the channel.
+	///
+	/// The `user_channel_id` parameter will be provided back in
+	/// [`Event::ChannelClosed::user_channel_id`] to allow tracking of which events correspond
+	/// with which `accept_inbound_channel_*` call.
+	///
+	/// The `funding_inputs` parameter provides which UTXOs to use for `our_funding_contribution`
+	/// along with the corresponding satisfaction weight. They must be able to cover any fees needed
+	/// to pay for the contributed weight to the funding transaction. This includes the witnesses
+	/// provided through calling [`ChannelManager::funding_transaction_signed`] after receiving
+	/// [`Event::FundingTransactionReadyForSigning`].
+	///
+	/// Note that this method will return an error and reject the channel if it requires support for
+	/// zero confirmations.
+	// TODO(dual_funding): Discussion on complications with 0conf dual-funded channels where "locking"
+	// of UTXOs used for funding would be required and other issues.
+	// See https://diyhpl.us/~bryan/irc/bitcoin/bitcoin-dev/linuxfoundation-pipermail/lightning-dev/2023-May/003922.txt
+	///
+	/// [`Event::OpenChannelRequest`]: events::Event::OpenChannelRequest
+	/// [`Event::OpenChannelRequest::channel_negotiation_type`]: events::Event::OpenChannelRequest::channel_negotiation_type
+	/// [`Event::ChannelClosed::user_channel_id`]: events::Event::ChannelClosed::user_channel_id
+	/// [`Event::FundingTransactionReadyForSigning`]: events::Event::FundingTransactionReadyForSigning
+	/// [`ChannelManager::funding_transaction_signed`]: ChannelManager::funding_transaction_signed
+	pub fn accept_inbound_channel_with_contribution(
+ &self, temporary_channel_id: &ChannelId, counterparty_node_id: &PublicKey,
+ user_channel_id: u128, config_overrides: Option<ChannelConfigOverrides>,
+ our_funding_contribution: Amount, funding_inputs: Vec<FundingTxInput>,
+ change_script: Option<ScriptBuf>,
+	) -> Result<(), APIError> {
+ self.do_accept_inbound_channel(
+ temporary_channel_id,
+ counterparty_node_id,
+ false,
+ user_channel_id,
+ config_overrides,
+ our_funding_contribution,
+ funding_inputs,
+ change_script,
  )
 	}
 
-	/// TODO(dual_funding): Allow contributions, pass intended amount and inputs
 	#[rustfmt::skip]
 	fn do_accept_inbound_channel(
- &self, temporary_channel_id: &ChannelId, counterparty_node_id: &PublicKey, accept_0conf: bool,
- user_channel_id: u128, config_overrides: Option<ChannelConfigOverrides>
+ &self, temporary_channel_id: &ChannelId, counterparty_node_id: &PublicKey,
+ accept_0conf: bool, user_channel_id: u128, config_overrides: Option<ChannelConfigOverrides>,
+ our_funding_contribution: Amount, funding_inputs: Vec<FundingTxInput>,
+ change_script: Option<ScriptBuf>,
 	) -> Result<(), APIError> {
+ if our_funding_contribution > Amount::MAX_MONEY {
+ return Err(APIError::APIMisuseError {
+ err: format!("the funding contribution must be smaller than the total bitcoin supply, it was {}", our_funding_contribution)
+ });
+ }
 
  let mut config = self.config.read().unwrap().clone();
 
@@ -9911,7 +9972,7 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
  &self.channel_type_features(), &peer_state.latest_features,
  &open_channel_msg,
  user_channel_id, &config, best_block_height,
- &self.logger,
+ &self.logger, our_funding_contribution, funding_inputs, change_script,
  ).map_err(|e| {
  let channel_id = open_channel_msg.common_fields.temporary_channel_id;
  MsgHandleErrInternal::from_chan_no_close(e, channel_id)
@@ -10055,7 +10116,7 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
 
  // Inbound V2 channels with contributed inputs are not considered unfunded.
  if let Some(unfunded_chan) = chan.as_unfunded_v2() {
- if unfunded_chan.funding_negotiation_context.our_funding_contribution > SignedAmount::ZERO {
+ if unfunded_chan.our_funding_contribution() > Amount::ZERO {
  continue;
  }
  }
@@ -10197,7 +10258,7 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
  &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, user_channel_id,
- &self.config.read().unwrap(), best_block_height, &self.logger,
+ &self.config.read().unwrap(), best_block_height, &self.logger, Amount::ZERO, vec![], None,
  ).map_err(|e| MsgHandleErrInternal::from_chan_no_close(e, msg.common_fields.temporary_channel_id))?;
  let message_send_event = MessageSendEvent::SendAcceptChannelV2 {
  node_id: *counterparty_node_id,

lightning/src/ln/channel.rs

@@ -6314,6 +6314,19 @@ where
  }
 	}
 
+	#[cfg(all(test))]
+	pub fn get_initial_counterparty_commitment_signatures_for_test<L: Deref>(
+ &mut self, funding: &mut FundingScope, logger: &L,
+ counterparty_next_commitment_point_override: PublicKey,
+	) -> Option<(Signature, Vec<Signature>)>
+	where
+ SP::Target: SignerProvider,
+ L::Target: Logger,
+	{
+ self.counterparty_next_commitment_point = Some(counterparty_next_commitment_point_override);
+ self.get_initial_counterparty_commitment_signatures(funding, logger)
+	}
+
 	fn check_funding_meets_minimum_depth(&self, funding: &FundingScope, height: u32) -> bool {
  let minimum_depth = self
  .minimum_depth(funding)
@@ -13946,7 +13959,9 @@ where
 	pub funding: FundingScope,
 	pub context: ChannelContext<SP>,
 	pub unfunded_context: UnfundedChannelContext,
-	pub funding_negotiation_context: FundingNegotiationContext,
+	funding_tx_locktime: LockTime,
+	#[allow(unused)] // TODO(dual_funding): Remove once initiating V2 channels is enabled.
+	pub funding_negotiation_context: Option<FundingNegotiationContext>,
 	/// The current interactive transaction construction session under negotiation.
 	pub interactive_tx_constructor: Option<InteractiveTxConstructor>,
 }
@@ -14021,7 +14036,8 @@ where
  funding,
  context,
  unfunded_context,
- funding_negotiation_context,
+ funding_tx_locktime,
+ funding_negotiation_context: Some(funding_negotiation_context),
  interactive_tx_constructor: None,
  };
  Ok(chan)
@@ -14096,29 +14112,28 @@ where
  },
  funding_feerate_sat_per_1000_weight: self.context.feerate_per_kw,
  second_per_commitment_point,
- locktime: self.funding_negotiation_context.funding_tx_locktime.to_consensus_u32(),
+ locktime: self.funding_tx_locktime.to_consensus_u32(),
  require_confirmed_inputs: None,
  }
 	}
 
 	/// 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!
-	/// TODO(dual_funding): Allow contributions, pass intended amount and inputs
 	#[allow(dead_code)] // TODO(dual_funding): Remove once V2 channels is enabled.
 	#[rustfmt::skip]
 	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,
- user_id: u128, config: &UserConfig, current_chain_height: u32, logger: &L,
+ their_features: &InitFeatures, msg: &msgs::OpenChannelV2, user_id: u128, config: &UserConfig,
+ current_chain_height: u32, logger: &L, our_funding_contribution: Amount,
+ our_funding_inputs: Vec<FundingTxInput>, change_script: Option<ScriptBuf>,
 	) -> Result<Self, ChannelError>
  where ES::Target: EntropySource,
  F::Target: FeeEstimator,
  L::Target: Logger,
 	{
- // TODO(dual_funding): Take these as input once supported
- let (our_funding_contribution, our_funding_contribution_sats) = (SignedAmount::ZERO, 0u64);
- let our_funding_inputs = Vec::new();
+ debug_assert!(our_funding_contribution <= Amount::MAX_MONEY);
+ let our_funding_contribution_sats = our_funding_contribution.to_sat();
 
  let channel_value_satoshis =
  our_funding_contribution_sats.saturating_add(msg.common_fields.funding_satoshis);
@@ -14161,39 +14176,33 @@ where
  &funding.get_counterparty_pubkeys().revocation_basepoint);
  context.channel_id = channel_id;
 
+ let funding_tx_locktime = LockTime::from_consensus(msg.locktime);
  let funding_negotiation_context = FundingNegotiationContext {
  is_initiator: false,
- our_funding_contribution,
- funding_tx_locktime: LockTime::from_consensus(msg.locktime),
+ our_funding_contribution: our_funding_contribution
+ .to_signed()
+ .expect("our_funding_contribution should not be greater than Amount::MAX_MONEY"),
+ funding_tx_locktime,
  funding_feerate_sat_per_1000_weight: msg.funding_feerate_sat_per_1000_weight,
  shared_funding_input: None,
  our_funding_inputs: our_funding_inputs.clone(),
  our_funding_outputs: Vec::new(),
- change_script: None,
- };
- let shared_funding_output = TxOut {
- value: Amount::from_sat(funding.get_value_satoshis()),
- script_pubkey: funding.get_funding_redeemscript().to_p2wsh(),
+ change_script,
  };
 
- let interactive_tx_constructor = Some(InteractiveTxConstructor::new(
- InteractiveTxConstructorArgs {
+ let mut interactive_tx_constructor = funding_negotiation_context
+ .into_interactive_tx_constructor(
+ &context,
+ &funding,
+ signer_provider,
  entropy_source,
  holder_node_id,
- counterparty_node_id,
- channel_id: context.channel_id,
- feerate_sat_per_kw: funding_negotiation_context.funding_feerate_sat_per_1000_weight,
- funding_tx_locktime: funding_negotiation_context.funding_tx_locktime,
- is_initiator: false,
- inputs_to_contribute: our_funding_inputs,
- shared_funding_input: None,
- shared_funding_output: SharedOwnedOutput::new(shared_funding_output, our_funding_contribution_sats),
- outputs_to_contribute: funding_negotiation_context.our_funding_outputs.clone(),
- }
- ).map_err(|err| {
- let reason = ClosureReason::ProcessingError { err: err.reason.to_string() };
- ChannelError::Close((err.reason.to_string(), reason))
- })?);
+ )
+ .map_err(|err| {
+ let reason = ClosureReason::ProcessingError { err: err.reason.to_string() };
+ ChannelError::Close((err.reason.to_string(), reason))
+ })?;
+ debug_assert!(interactive_tx_constructor.take_initiator_first_message().is_none());
 
  let unfunded_context = UnfundedChannelContext {
  unfunded_channel_age_ticks: 0,
@@ -14202,9 +14211,10 @@ where
  Ok(Self {
  funding,
  context,
- funding_negotiation_context,
- interactive_tx_constructor,
  unfunded_context,
+ funding_tx_locktime,
+ funding_negotiation_context: None,
+ interactive_tx_constructor: Some(interactive_tx_constructor),
  })
 	}
 
@@ -14267,8 +14277,7 @@ where
  }),
  channel_type: Some(self.funding.get_channel_type().clone()),
  },
- funding_satoshis: self.funding_negotiation_context.our_funding_contribution.to_sat()
- as u64,
+ funding_satoshis: self.our_funding_contribution().to_sat(),
  second_per_commitment_point,
  require_confirmed_inputs: None,
  }
@@ -14283,6 +14292,10 @@ where
 	pub fn get_accept_channel_v2_message(&self) -> msgs::AcceptChannelV2 {
  self.generate_accept_channel_v2_message()
 	}
+
+	pub fn our_funding_contribution(&self) -> Amount {
+ Amount::from_sat(self.funding.value_to_self_msat / 1000)
+	}
 }
 
 // Unfunded channel utilities

lightning/src/ln/channelmanager.rs

@@ -30,7 +30,7 @@ use bitcoin::hashes::{Hash, HashEngine, HmacEngine};
 
 use bitcoin::secp256k1::Secp256k1;
 use bitcoin::secp256k1::{PublicKey, SecretKey};
-use bitcoin::{secp256k1, Sequence, SignedAmount};
+use bitcoin::{secp256k1, Amount, ScriptBuf, Sequence};
 
 use crate::blinded_path::message::{
 	AsyncPaymentsContext, BlindedMessagePath, MessageForwardNode, OffersContext,
@@ -65,7 +65,7 @@ use crate::ln::channel::{
 	WithChannelContext,
 };
 use crate::ln::channel_state::ChannelDetails;
-use crate::ln::funding::SpliceContribution;
+use crate::ln::funding::{FundingTxInput, SpliceContribution};
 use crate::ln::inbound_payment;
 use crate::ln::interactivetxs::InteractiveTxMessageSend;
 use crate::ln::msgs;
@@ -9814,6 +9814,9 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
  false,
  user_channel_id,
  config_overrides,
+ Amount::ZERO,
+ vec![],
+ None,
  )
 	}
 
@@ -9845,15 +9848,73 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
  true,
  user_channel_id,
  config_overrides,
+ Amount::ZERO,
+ vec![],
+ None,
+ )
+	}
+
+	/// Accepts a request to open a dual-funded channel with a contribution provided after an
+	/// [`Event::OpenChannelRequest`].
+	///
+	/// The [`Event::OpenChannelRequest::channel_negotiation_type`] field will indicate the open channel
+	/// request is for a dual-funded channel when the variant is [`InboundChannelFunds::DualFunded`].
+	///
+	/// The `temporary_channel_id` parameter indicates which inbound channel should be accepted,
+	/// and the `counterparty_node_id` parameter is the id of the peer that has requested to open
+	/// the channel.
+	///
+	/// The `user_channel_id` parameter will be provided back in
+	/// [`Event::ChannelClosed::user_channel_id`] to allow tracking of which events correspond
+	/// with which `accept_inbound_channel_*` call.
+	///
+	/// The `funding_inputs` parameter provides which UTXOs to use for `our_funding_contribution`
+	/// along with the corresponding satisfaction weight. They must be able to cover any fees needed
+	/// to pay for the contributed weight to the funding transaction. This includes the witnesses
+	/// provided through calling [`ChannelManager::funding_transaction_signed`] after receiving
+	/// [`Event::FundingTransactionReadyForSigning`].
+	///
+	/// Note that this method will return an error and reject the channel if it requires support for
+	/// zero confirmations.
+	// TODO(dual_funding): Discussion on complications with 0conf dual-funded channels where "locking"
+	// of UTXOs used for funding would be required and other issues.
+	// See https://diyhpl.us/~bryan/irc/bitcoin/bitcoin-dev/linuxfoundation-pipermail/lightning-dev/2023-May/003922.txt
+	///
+	/// [`Event::OpenChannelRequest`]: events::Event::OpenChannelRequest
+	/// [`Event::OpenChannelRequest::channel_negotiation_type`]: events::Event::OpenChannelRequest::channel_negotiation_type
+	/// [`Event::ChannelClosed::user_channel_id`]: events::Event::ChannelClosed::user_channel_id
+	/// [`Event::FundingTransactionReadyForSigning`]: events::Event::FundingTransactionReadyForSigning
+	/// [`ChannelManager::funding_transaction_signed`]: ChannelManager::funding_transaction_signed
+	pub fn accept_inbound_channel_with_contribution(
+ &self, temporary_channel_id: &ChannelId, counterparty_node_id: &PublicKey,
+ user_channel_id: u128, config_overrides: Option<ChannelConfigOverrides>,
+ our_funding_contribution: Amount, funding_inputs: Vec<FundingTxInput>,
+ change_script: Option<ScriptBuf>,
+	) -> Result<(), APIError> {
+ self.do_accept_inbound_channel(
+ temporary_channel_id,
+ counterparty_node_id,
+ false,
+ user_channel_id,
+ config_overrides,
+ our_funding_contribution,
+ funding_inputs,
+ change_script,
  )
 	}
 
-	/// TODO(dual_funding): Allow contributions, pass intended amount and inputs
 	#[rustfmt::skip]
 	fn do_accept_inbound_channel(
- &self, temporary_channel_id: &ChannelId, counterparty_node_id: &PublicKey, accept_0conf: bool,
- user_channel_id: u128, config_overrides: Option<ChannelConfigOverrides>
+ &self, temporary_channel_id: &ChannelId, counterparty_node_id: &PublicKey,
+ accept_0conf: bool, user_channel_id: u128, config_overrides: Option<ChannelConfigOverrides>,
+ our_funding_contribution: Amount, funding_inputs: Vec<FundingTxInput>,
+ change_script: Option<ScriptBuf>,
 	) -> Result<(), APIError> {
+ if our_funding_contribution > Amount::MAX_MONEY {
+ return Err(APIError::APIMisuseError {
+ err: format!("the funding contribution must be smaller than the total bitcoin supply, it was {}", our_funding_contribution)
+ });
+ }
 
  let mut config = self.config.read().unwrap().clone();
 
@@ -9911,7 +9972,7 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
  &self.channel_type_features(), &peer_state.latest_features,
  &open_channel_msg,
  user_channel_id, &config, best_block_height,
- &self.logger,
+ &self.logger, our_funding_contribution, funding_inputs, change_script,
  ).map_err(|e| {
  let channel_id = open_channel_msg.common_fields.temporary_channel_id;
  MsgHandleErrInternal::from_chan_no_close(e, channel_id)
@@ -10055,7 +10116,7 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
 
  // Inbound V2 channels with contributed inputs are not considered unfunded.
  if let Some(unfunded_chan) = chan.as_unfunded_v2() {
- if unfunded_chan.funding_negotiation_context.our_funding_contribution > SignedAmount::ZERO {
+ if unfunded_chan.our_funding_contribution() > Amount::ZERO {
  continue;
  }
  }
@@ -10197,7 +10258,7 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
  &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, user_channel_id,
- &self.config.read().unwrap(), best_block_height, &self.logger,
+ &self.config.read().unwrap(), best_block_height, &self.logger, Amount::ZERO, vec![], None,
  ).map_err(|e| MsgHandleErrInternal::from_chan_no_close(e, msg.common_fields.temporary_channel_id))?;
  let message_send_event = MessageSendEvent::SendAcceptChannelV2 {
  node_id: *counterparty_node_id,

lightning/src/ln/channel.rs

@@ -6314,6 +6314,19 @@ where
  }
 	}
 
+	#[cfg(all(test))]
+	pub fn get_initial_counterparty_commitment_signatures_for_test<L: Deref>(
+ &mut self, funding: &mut FundingScope, logger: &L,
+ counterparty_next_commitment_point_override: PublicKey,
+	) -> Option<(Signature, Vec<Signature>)>
+	where
+ SP::Target: SignerProvider,
+ L::Target: Logger,
+	{
+ self.counterparty_next_commitment_point = Some(counterparty_next_commitment_point_override);
+ self.get_initial_counterparty_commitment_signatures(funding, logger)
+	}
+
 	fn check_funding_meets_minimum_depth(&self, funding: &FundingScope, height: u32) -> bool {
  let minimum_depth = self
  .minimum_depth(funding)
@@ -13946,7 +13959,9 @@ where
 	pub funding: FundingScope,
 	pub context: ChannelContext<SP>,
 	pub unfunded_context: UnfundedChannelContext,
-	pub funding_negotiation_context: FundingNegotiationContext,
+	funding_tx_locktime: LockTime,
+	#[allow(unused)] // TODO(dual_funding): Remove once initiating V2 channels is enabled.
+	pub funding_negotiation_context: Option<FundingNegotiationContext>,
 	/// The current interactive transaction construction session under negotiation.
 	pub interactive_tx_constructor: Option<InteractiveTxConstructor>,
 }
@@ -14021,7 +14036,8 @@ where
  funding,
  context,
  unfunded_context,
- funding_negotiation_context,
+ funding_tx_locktime,
+ funding_negotiation_context: Some(funding_negotiation_context),
  interactive_tx_constructor: None,
  };
  Ok(chan)
@@ -14096,29 +14112,28 @@ where
  },
  funding_feerate_sat_per_1000_weight: self.context.feerate_per_kw,
  second_per_commitment_point,
- locktime: self.funding_negotiation_context.funding_tx_locktime.to_consensus_u32(),
+ locktime: self.funding_tx_locktime.to_consensus_u32(),
  require_confirmed_inputs: None,
  }
 	}
 
 	/// 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!
-	/// TODO(dual_funding): Allow contributions, pass intended amount and inputs
 	#[allow(dead_code)] // TODO(dual_funding): Remove once V2 channels is enabled.
 	#[rustfmt::skip]
 	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,
- user_id: u128, config: &UserConfig, current_chain_height: u32, logger: &L,
+ their_features: &InitFeatures, msg: &msgs::OpenChannelV2, user_id: u128, config: &UserConfig,
+ current_chain_height: u32, logger: &L, our_funding_contribution: Amount,
+ our_funding_inputs: Vec<FundingTxInput>, change_script: Option<ScriptBuf>,
 	) -> Result<Self, ChannelError>
  where ES::Target: EntropySource,
  F::Target: FeeEstimator,
  L::Target: Logger,
 	{
- // TODO(dual_funding): Take these as input once supported
- let (our_funding_contribution, our_funding_contribution_sats) = (SignedAmount::ZERO, 0u64);
- let our_funding_inputs = Vec::new();
+ debug_assert!(our_funding_contribution <= Amount::MAX_MONEY);
+ let our_funding_contribution_sats = our_funding_contribution.to_sat();
 
  let channel_value_satoshis =
  our_funding_contribution_sats.saturating_add(msg.common_fields.funding_satoshis);
@@ -14161,39 +14176,33 @@ where
  &funding.get_counterparty_pubkeys().revocation_basepoint);
  context.channel_id = channel_id;
 
+ let funding_tx_locktime = LockTime::from_consensus(msg.locktime);
  let funding_negotiation_context = FundingNegotiationContext {
  is_initiator: false,
- our_funding_contribution,
- funding_tx_locktime: LockTime::from_consensus(msg.locktime),
+ our_funding_contribution: our_funding_contribution
+ .to_signed()
+ .expect("our_funding_contribution should not be greater than Amount::MAX_MONEY"),
+ funding_tx_locktime,
  funding_feerate_sat_per_1000_weight: msg.funding_feerate_sat_per_1000_weight,
  shared_funding_input: None,
  our_funding_inputs: our_funding_inputs.clone(),
  our_funding_outputs: Vec::new(),
- change_script: None,
- };
- let shared_funding_output = TxOut {
- value: Amount::from_sat(funding.get_value_satoshis()),
- script_pubkey: funding.get_funding_redeemscript().to_p2wsh(),
+ change_script,
  };
 
- let interactive_tx_constructor = Some(InteractiveTxConstructor::new(
- InteractiveTxConstructorArgs {
+ let mut interactive_tx_constructor = funding_negotiation_context
+ .into_interactive_tx_constructor(
+ &context,
+ &funding,
+ signer_provider,
  entropy_source,
  holder_node_id,
- counterparty_node_id,
- channel_id: context.channel_id,
- feerate_sat_per_kw: funding_negotiation_context.funding_feerate_sat_per_1000_weight,
- funding_tx_locktime: funding_negotiation_context.funding_tx_locktime,
- is_initiator: false,
- inputs_to_contribute: our_funding_inputs,
- shared_funding_input: None,
- shared_funding_output: SharedOwnedOutput::new(shared_funding_output, our_funding_contribution_sats),
- outputs_to_contribute: funding_negotiation_context.our_funding_outputs.clone(),
- }
- ).map_err(|err| {
- let reason = ClosureReason::ProcessingError { err: err.reason.to_string() };
- ChannelError::Close((err.reason.to_string(), reason))
- })?);
+ )
+ .map_err(|err| {
+ let reason = ClosureReason::ProcessingError { err: err.reason.to_string() };
+ ChannelError::Close((err.reason.to_string(), reason))
+ })?;
+ debug_assert!(interactive_tx_constructor.take_initiator_first_message().is_none());
 
  let unfunded_context = UnfundedChannelContext {
  unfunded_channel_age_ticks: 0,
@@ -14202,9 +14211,10 @@ where
  Ok(Self {
  funding,
  context,
- funding_negotiation_context,
- interactive_tx_constructor,
  unfunded_context,
+ funding_tx_locktime,
+ funding_negotiation_context: None,
+ interactive_tx_constructor: Some(interactive_tx_constructor),
  })
 	}
 
@@ -14267,8 +14277,7 @@ where
  }),
  channel_type: Some(self.funding.get_channel_type().clone()),
  },
- funding_satoshis: self.funding_negotiation_context.our_funding_contribution.to_sat()
- as u64,
+ funding_satoshis: self.our_funding_contribution().to_sat(),
  second_per_commitment_point,
  require_confirmed_inputs: None,
  }
@@ -14283,6 +14292,10 @@ where
 	pub fn get_accept_channel_v2_message(&self) -> msgs::AcceptChannelV2 {
  self.generate_accept_channel_v2_message()
 	}
+
+	pub fn our_funding_contribution(&self) -> Amount {
+ Amount::from_sat(self.funding.value_to_self_msat / 1000)
+	}
 }
 
 // Unfunded channel utilities

lightning/src/ln/channelmanager.rs

@@ -30,7 +30,7 @@ use bitcoin::hashes::{Hash, HashEngine, HmacEngine};
 
 use bitcoin::secp256k1::Secp256k1;
 use bitcoin::secp256k1::{PublicKey, SecretKey};
-use bitcoin::{secp256k1, Sequence, SignedAmount};
+use bitcoin::{secp256k1, Amount, ScriptBuf, Sequence};
 
 use crate::blinded_path::message::{
 	AsyncPaymentsContext, BlindedMessagePath, MessageForwardNode, OffersContext,
@@ -65,7 +65,7 @@ use crate::ln::channel::{
 	WithChannelContext,
 };
 use crate::ln::channel_state::ChannelDetails;
-use crate::ln::funding::SpliceContribution;
+use crate::ln::funding::{FundingTxInput, SpliceContribution};
 use crate::ln::inbound_payment;
 use crate::ln::interactivetxs::InteractiveTxMessageSend;
 use crate::ln::msgs;
@@ -9814,6 +9814,9 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
  false,
  user_channel_id,
  config_overrides,
+ Amount::ZERO,
+ vec![],
+ None,
  )
 	}
 
@@ -9845,15 +9848,73 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
  true,
  user_channel_id,
  config_overrides,
+ Amount::ZERO,
+ vec![],
+ None,
+ )
+	}
+
+	/// Accepts a request to open a dual-funded channel with a contribution provided after an
+	/// [`Event::OpenChannelRequest`].
+	///
+	/// The [`Event::OpenChannelRequest::channel_negotiation_type`] field will indicate the open channel
+	/// request is for a dual-funded channel when the variant is [`InboundChannelFunds::DualFunded`].
+	///
+	/// The `temporary_channel_id` parameter indicates which inbound channel should be accepted,
+	/// and the `counterparty_node_id` parameter is the id of the peer that has requested to open
+	/// the channel.
+	///
+	/// The `user_channel_id` parameter will be provided back in
+	/// [`Event::ChannelClosed::user_channel_id`] to allow tracking of which events correspond
+	/// with which `accept_inbound_channel_*` call.
+	///
+	/// The `funding_inputs` parameter provides which UTXOs to use for `our_funding_contribution`
+	/// along with the corresponding satisfaction weight. They must be able to cover any fees needed
+	/// to pay for the contributed weight to the funding transaction. This includes the witnesses
+	/// provided through calling [`ChannelManager::funding_transaction_signed`] after receiving
+	/// [`Event::FundingTransactionReadyForSigning`].
+	///
+	/// Note that this method will return an error and reject the channel if it requires support for
+	/// zero confirmations.
+	// TODO(dual_funding): Discussion on complications with 0conf dual-funded channels where "locking"
+	// of UTXOs used for funding would be required and other issues.
+	// See https://diyhpl.us/~bryan/irc/bitcoin/bitcoin-dev/linuxfoundation-pipermail/lightning-dev/2023-May/003922.txt
+	///
+	/// [`Event::OpenChannelRequest`]: events::Event::OpenChannelRequest
+	/// [`Event::OpenChannelRequest::channel_negotiation_type`]: events::Event::OpenChannelRequest::channel_negotiation_type
+	/// [`Event::ChannelClosed::user_channel_id`]: events::Event::ChannelClosed::user_channel_id
+	/// [`Event::FundingTransactionReadyForSigning`]: events::Event::FundingTransactionReadyForSigning
+	/// [`ChannelManager::funding_transaction_signed`]: ChannelManager::funding_transaction_signed
+	pub fn accept_inbound_channel_with_contribution(
+ &self, temporary_channel_id: &ChannelId, counterparty_node_id: &PublicKey,
+ user_channel_id: u128, config_overrides: Option<ChannelConfigOverrides>,
+ our_funding_contribution: Amount, funding_inputs: Vec<FundingTxInput>,
+ change_script: Option<ScriptBuf>,
+	) -> Result<(), APIError> {
+ self.do_accept_inbound_channel(
+ temporary_channel_id,
+ counterparty_node_id,
+ false,
+ user_channel_id,
+ config_overrides,
+ our_funding_contribution,
+ funding_inputs,
+ change_script,
  )
 	}
 
-	/// TODO(dual_funding): Allow contributions, pass intended amount and inputs
 	#[rustfmt::skip]
 	fn do_accept_inbound_channel(
- &self, temporary_channel_id: &ChannelId, counterparty_node_id: &PublicKey, accept_0conf: bool,
- user_channel_id: u128, config_overrides: Option<ChannelConfigOverrides>
+ &self, temporary_channel_id: &ChannelId, counterparty_node_id: &PublicKey,
+ accept_0conf: bool, user_channel_id: u128, config_overrides: Option<ChannelConfigOverrides>,
+ our_funding_contribution: Amount, funding_inputs: Vec<FundingTxInput>,
+ change_script: Option<ScriptBuf>,
 	) -> Result<(), APIError> {
+ if our_funding_contribution > Amount::MAX_MONEY {
+ return Err(APIError::APIMisuseError {
+ err: format!("the funding contribution must be smaller than the total bitcoin supply, it was {}", our_funding_contribution)
+ });
+ }
 
  let mut config = self.config.read().unwrap().clone();
 
@@ -9911,7 +9972,7 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
  &self.channel_type_features(), &peer_state.latest_features,
  &open_channel_msg,
  user_channel_id, &config, best_block_height,
- &self.logger,
+ &self.logger, our_funding_contribution, funding_inputs, change_script,
  ).map_err(|e| {
  let channel_id = open_channel_msg.common_fields.temporary_channel_id;
  MsgHandleErrInternal::from_chan_no_close(e, channel_id)
@@ -10055,7 +10116,7 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
 
  // Inbound V2 channels with contributed inputs are not considered unfunded.
  if let Some(unfunded_chan) = chan.as_unfunded_v2() {
- if unfunded_chan.funding_negotiation_context.our_funding_contribution > SignedAmount::ZERO {
+ if unfunded_chan.our_funding_contribution() > Amount::ZERO {
  continue;
  }
  }
@@ -10197,7 +10258,7 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
  &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, user_channel_id,
- &self.config.read().unwrap(), best_block_height, &self.logger,
+ &self.config.read().unwrap(), best_block_height, &self.logger, Amount::ZERO, vec![], None,
  ).map_err(|e| MsgHandleErrInternal::from_chan_no_close(e, msg.common_fields.temporary_channel_id))?;
  let message_send_event = MessageSendEvent::SendAcceptChannelV2 {
  node_id: *counterparty_node_id,

lightning/src/ln/channel.rs

@@ -6314,6 +6314,19 @@ where
  }
 	}
 
+	#[cfg(all(test))]
+	pub fn get_initial_counterparty_commitment_signatures_for_test<L: Deref>(
+ &mut self, funding: &mut FundingScope, logger: &L,
+ counterparty_next_commitment_point_override: PublicKey,
+	) -> Option<(Signature, Vec<Signature>)>
+	where
+ SP::Target: SignerProvider,
+ L::Target: Logger,
+	{
+ self.counterparty_next_commitment_point = Some(counterparty_next_commitment_point_override);
+ self.get_initial_counterparty_commitment_signatures(funding, logger)
+	}
+
 	fn check_funding_meets_minimum_depth(&self, funding: &FundingScope, height: u32) -> bool {
  let minimum_depth = self
  .minimum_depth(funding)
@@ -13946,7 +13959,9 @@ where
 	pub funding: FundingScope,
 	pub context: ChannelContext<SP>,
 	pub unfunded_context: UnfundedChannelContext,
-	pub funding_negotiation_context: FundingNegotiationContext,
+	funding_tx_locktime: LockTime,
+	#[allow(unused)] // TODO(dual_funding): Remove once initiating V2 channels is enabled.
+	pub funding_negotiation_context: Option<FundingNegotiationContext>,
 	/// The current interactive transaction construction session under negotiation.
 	pub interactive_tx_constructor: Option<InteractiveTxConstructor>,
 }
@@ -14021,7 +14036,8 @@ where
  funding,
  context,
  unfunded_context,
- funding_negotiation_context,
+ funding_tx_locktime,
+ funding_negotiation_context: Some(funding_negotiation_context),
  interactive_tx_constructor: None,
  };
  Ok(chan)
@@ -14096,29 +14112,28 @@ where
  },
  funding_feerate_sat_per_1000_weight: self.context.feerate_per_kw,
  second_per_commitment_point,
- locktime: self.funding_negotiation_context.funding_tx_locktime.to_consensus_u32(),
+ locktime: self.funding_tx_locktime.to_consensus_u32(),
  require_confirmed_inputs: None,
  }
 	}
 
 	/// 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!
-	/// TODO(dual_funding): Allow contributions, pass intended amount and inputs
 	#[allow(dead_code)] // TODO(dual_funding): Remove once V2 channels is enabled.
 	#[rustfmt::skip]
 	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,
- user_id: u128, config: &UserConfig, current_chain_height: u32, logger: &L,
+ their_features: &InitFeatures, msg: &msgs::OpenChannelV2, user_id: u128, config: &UserConfig,
+ current_chain_height: u32, logger: &L, our_funding_contribution: Amount,
+ our_funding_inputs: Vec<FundingTxInput>, change_script: Option<ScriptBuf>,
 	) -> Result<Self, ChannelError>
  where ES::Target: EntropySource,
  F::Target: FeeEstimator,
  L::Target: Logger,
 	{
- // TODO(dual_funding): Take these as input once supported
- let (our_funding_contribution, our_funding_contribution_sats) = (SignedAmount::ZERO, 0u64);
- let our_funding_inputs = Vec::new();
+ debug_assert!(our_funding_contribution <= Amount::MAX_MONEY);
+ let our_funding_contribution_sats = our_funding_contribution.to_sat();
 
  let channel_value_satoshis =
  our_funding_contribution_sats.saturating_add(msg.common_fields.funding_satoshis);
@@ -14161,39 +14176,33 @@ where
  &funding.get_counterparty_pubkeys().revocation_basepoint);
  context.channel_id = channel_id;
 
+ let funding_tx_locktime = LockTime::from_consensus(msg.locktime);
  let funding_negotiation_context = FundingNegotiationContext {
  is_initiator: false,
- our_funding_contribution,
- funding_tx_locktime: LockTime::from_consensus(msg.locktime),
+ our_funding_contribution: our_funding_contribution
+ .to_signed()
+ .expect("our_funding_contribution should not be greater than Amount::MAX_MONEY"),
+ funding_tx_locktime,
  funding_feerate_sat_per_1000_weight: msg.funding_feerate_sat_per_1000_weight,
  shared_funding_input: None,
  our_funding_inputs: our_funding_inputs.clone(),
  our_funding_outputs: Vec::new(),
- change_script: None,
- };
- let shared_funding_output = TxOut {
- value: Amount::from_sat(funding.get_value_satoshis()),
- script_pubkey: funding.get_funding_redeemscript().to_p2wsh(),
+ change_script,
  };
 
- let interactive_tx_constructor = Some(InteractiveTxConstructor::new(
- InteractiveTxConstructorArgs {
+ let mut interactive_tx_constructor = funding_negotiation_context
+ .into_interactive_tx_constructor(
+ &context,
+ &funding,
+ signer_provider,
  entropy_source,
  holder_node_id,
- counterparty_node_id,
- channel_id: context.channel_id,
- feerate_sat_per_kw: funding_negotiation_context.funding_feerate_sat_per_1000_weight,
- funding_tx_locktime: funding_negotiation_context.funding_tx_locktime,
- is_initiator: false,
- inputs_to_contribute: our_funding_inputs,
- shared_funding_input: None,
- shared_funding_output: SharedOwnedOutput::new(shared_funding_output, our_funding_contribution_sats),
- outputs_to_contribute: funding_negotiation_context.our_funding_outputs.clone(),
- }
- ).map_err(|err| {
- let reason = ClosureReason::ProcessingError { err: err.reason.to_string() };
- ChannelError::Close((err.reason.to_string(), reason))
- })?);
+ )
+ .map_err(|err| {
+ let reason = ClosureReason::ProcessingError { err: err.reason.to_string() };
+ ChannelError::Close((err.reason.to_string(), reason))
+ })?;
+ debug_assert!(interactive_tx_constructor.take_initiator_first_message().is_none());
 
  let unfunded_context = UnfundedChannelContext {
  unfunded_channel_age_ticks: 0,
@@ -14202,9 +14211,10 @@ where
  Ok(Self {
  funding,
  context,
- funding_negotiation_context,
- interactive_tx_constructor,
  unfunded_context,
+ funding_tx_locktime,
+ funding_negotiation_context: None,
+ interactive_tx_constructor: Some(interactive_tx_constructor),
  })
 	}
 
@@ -14267,8 +14277,7 @@ where
  }),
  channel_type: Some(self.funding.get_channel_type().clone()),
  },
- funding_satoshis: self.funding_negotiation_context.our_funding_contribution.to_sat()
- as u64,
+ funding_satoshis: self.our_funding_contribution().to_sat(),
  second_per_commitment_point,
  require_confirmed_inputs: None,
  }
@@ -14283,6 +14292,10 @@ where
 	pub fn get_accept_channel_v2_message(&self) -> msgs::AcceptChannelV2 {
  self.generate_accept_channel_v2_message()
 	}
+
+	pub fn our_funding_contribution(&self) -> Amount {
+ Amount::from_sat(self.funding.value_to_self_msat / 1000)
+	}
 }
 
 // Unfunded channel utilities

lightning/src/ln/channelmanager.rs

@@ -30,7 +30,7 @@ use bitcoin::hashes::{Hash, HashEngine, HmacEngine};
 
 use bitcoin::secp256k1::Secp256k1;
 use bitcoin::secp256k1::{PublicKey, SecretKey};
-use bitcoin::{secp256k1, Sequence, SignedAmount};
+use bitcoin::{secp256k1, Amount, ScriptBuf, Sequence};
 
 use crate::blinded_path::message::{
 	AsyncPaymentsContext, BlindedMessagePath, MessageForwardNode, OffersContext,
@@ -65,7 +65,7 @@ use crate::ln::channel::{
 	WithChannelContext,
 };
 use crate::ln::channel_state::ChannelDetails;
-use crate::ln::funding::SpliceContribution;
+use crate::ln::funding::{FundingTxInput, SpliceContribution};
 use crate::ln::inbound_payment;
 use crate::ln::interactivetxs::InteractiveTxMessageSend;
 use crate::ln::msgs;
@@ -9814,6 +9814,9 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
  false,
  user_channel_id,
  config_overrides,
+ Amount::ZERO,
+ vec![],
+ None,
  )
 	}
 
@@ -9845,15 +9848,73 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
  true,
  user_channel_id,
  config_overrides,
+ Amount::ZERO,
+ vec![],
+ None,
+ )
+	}
+
+	/// Accepts a request to open a dual-funded channel with a contribution provided after an
+	/// [`Event::OpenChannelRequest`].
+	///
+	/// The [`Event::OpenChannelRequest::channel_negotiation_type`] field will indicate the open channel
+	/// request is for a dual-funded channel when the variant is [`InboundChannelFunds::DualFunded`].
+	///
+	/// The `temporary_channel_id` parameter indicates which inbound channel should be accepted,
+	/// and the `counterparty_node_id` parameter is the id of the peer that has requested to open
+	/// the channel.
+	///
+	/// The `user_channel_id` parameter will be provided back in
+	/// [`Event::ChannelClosed::user_channel_id`] to allow tracking of which events correspond
+	/// with which `accept_inbound_channel_*` call.
+	///
+	/// The `funding_inputs` parameter provides which UTXOs to use for `our_funding_contribution`
+	/// along with the corresponding satisfaction weight. They must be able to cover any fees needed
+	/// to pay for the contributed weight to the funding transaction. This includes the witnesses
+	/// provided through calling [`ChannelManager::funding_transaction_signed`] after receiving
+	/// [`Event::FundingTransactionReadyForSigning`].
+	///
+	/// Note that this method will return an error and reject the channel if it requires support for
+	/// zero confirmations.
+	// TODO(dual_funding): Discussion on complications with 0conf dual-funded channels where "locking"
+	// of UTXOs used for funding would be required and other issues.
+	// See https://diyhpl.us/~bryan/irc/bitcoin/bitcoin-dev/linuxfoundation-pipermail/lightning-dev/2023-May/003922.txt
+	///
+	/// [`Event::OpenChannelRequest`]: events::Event::OpenChannelRequest
+	/// [`Event::OpenChannelRequest::channel_negotiation_type`]: events::Event::OpenChannelRequest::channel_negotiation_type
+	/// [`Event::ChannelClosed::user_channel_id`]: events::Event::ChannelClosed::user_channel_id
+	/// [`Event::FundingTransactionReadyForSigning`]: events::Event::FundingTransactionReadyForSigning
+	/// [`ChannelManager::funding_transaction_signed`]: ChannelManager::funding_transaction_signed
+	pub fn accept_inbound_channel_with_contribution(
+ &self, temporary_channel_id: &ChannelId, counterparty_node_id: &PublicKey,
+ user_channel_id: u128, config_overrides: Option<ChannelConfigOverrides>,
+ our_funding_contribution: Amount, funding_inputs: Vec<FundingTxInput>,
+ change_script: Option<ScriptBuf>,
+	) -> Result<(), APIError> {
+ self.do_accept_inbound_channel(
+ temporary_channel_id,
+ counterparty_node_id,
+ false,
+ user_channel_id,
+ config_overrides,
+ our_funding_contribution,
+ funding_inputs,
+ change_script,
  )
 	}
 
-	/// TODO(dual_funding): Allow contributions, pass intended amount and inputs
 	#[rustfmt::skip]
 	fn do_accept_inbound_channel(
- &self, temporary_channel_id: &ChannelId, counterparty_node_id: &PublicKey, accept_0conf: bool,
- user_channel_id: u128, config_overrides: Option<ChannelConfigOverrides>
+ &self, temporary_channel_id: &ChannelId, counterparty_node_id: &PublicKey,
+ accept_0conf: bool, user_channel_id: u128, config_overrides: Option<ChannelConfigOverrides>,
+ our_funding_contribution: Amount, funding_inputs: Vec<FundingTxInput>,
+ change_script: Option<ScriptBuf>,
 	) -> Result<(), APIError> {
+ if our_funding_contribution > Amount::MAX_MONEY {
+ return Err(APIError::APIMisuseError {
+ err: format!("the funding contribution must be smaller than the total bitcoin supply, it was {}", our_funding_contribution)
+ });
+ }
 
  let mut config = self.config.read().unwrap().clone();
 
@@ -9911,7 +9972,7 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
  &self.channel_type_features(), &peer_state.latest_features,
  &open_channel_msg,
  user_channel_id, &config, best_block_height,
- &self.logger,
+ &self.logger, our_funding_contribution, funding_inputs, change_script,
  ).map_err(|e| {
  let channel_id = open_channel_msg.common_fields.temporary_channel_id;
  MsgHandleErrInternal::from_chan_no_close(e, channel_id)
@@ -10055,7 +10116,7 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
 
  // Inbound V2 channels with contributed inputs are not considered unfunded.
  if let Some(unfunded_chan) = chan.as_unfunded_v2() {
- if unfunded_chan.funding_negotiation_context.our_funding_contribution > SignedAmount::ZERO {
+ if unfunded_chan.our_funding_contribution() > Amount::ZERO {
  continue;
  }
  }
@@ -10197,7 +10258,7 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
  &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, user_channel_id,
- &self.config.read().unwrap(), best_block_height, &self.logger,
+ &self.config.read().unwrap(), best_block_height, &self.logger, Amount::ZERO, vec![], None,
  ).map_err(|e| MsgHandleErrInternal::from_chan_no_close(e, msg.common_fields.temporary_channel_id))?;
  let message_send_event = MessageSendEvent::SendAcceptChannelV2 {
  node_id: *counterparty_node_id,

lightning/src/ln/channel.rs

@@ -6314,6 +6314,19 @@ where
  }
 	}
 
+	#[cfg(all(test))]
+	pub fn get_initial_counterparty_commitment_signatures_for_test<L: Deref>(
+ &mut self, funding: &mut FundingScope, logger: &L,
+ counterparty_next_commitment_point_override: PublicKey,
+	) -> Option<(Signature, Vec<Signature>)>
+	where
+ SP::Target: SignerProvider,
+ L::Target: Logger,
+	{
+ self.counterparty_next_commitment_point = Some(counterparty_next_commitment_point_override);
+ self.get_initial_counterparty_commitment_signatures(funding, logger)
+	}
+
 	fn check_funding_meets_minimum_depth(&self, funding: &FundingScope, height: u32) -> bool {
  let minimum_depth = self
  .minimum_depth(funding)
@@ -13946,7 +13959,9 @@ where
 	pub funding: FundingScope,
 	pub context: ChannelContext<SP>,
 	pub unfunded_context: UnfundedChannelContext,
-	pub funding_negotiation_context: FundingNegotiationContext,
+	funding_tx_locktime: LockTime,
+	#[allow(unused)] // TODO(dual_funding): Remove once initiating V2 channels is enabled.
+	pub funding_negotiation_context: Option<FundingNegotiationContext>,
 	/// The current interactive transaction construction session under negotiation.
 	pub interactive_tx_constructor: Option<InteractiveTxConstructor>,
 }
@@ -14021,7 +14036,8 @@ where
  funding,
  context,
  unfunded_context,
- funding_negotiation_context,
+ funding_tx_locktime,
+ funding_negotiation_context: Some(funding_negotiation_context),
  interactive_tx_constructor: None,
  };
  Ok(chan)
@@ -14096,29 +14112,28 @@ where
  },
  funding_feerate_sat_per_1000_weight: self.context.feerate_per_kw,
  second_per_commitment_point,
- locktime: self.funding_negotiation_context.funding_tx_locktime.to_consensus_u32(),
+ locktime: self.funding_tx_locktime.to_consensus_u32(),
  require_confirmed_inputs: None,
  }
 	}
 
 	/// 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!
-	/// TODO(dual_funding): Allow contributions, pass intended amount and inputs
 	#[allow(dead_code)] // TODO(dual_funding): Remove once V2 channels is enabled.
 	#[rustfmt::skip]
 	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,
- user_id: u128, config: &UserConfig, current_chain_height: u32, logger: &L,
+ their_features: &InitFeatures, msg: &msgs::OpenChannelV2, user_id: u128, config: &UserConfig,
+ current_chain_height: u32, logger: &L, our_funding_contribution: Amount,
+ our_funding_inputs: Vec<FundingTxInput>, change_script: Option<ScriptBuf>,
 	) -> Result<Self, ChannelError>
  where ES::Target: EntropySource,
  F::Target: FeeEstimator,
  L::Target: Logger,
 	{
- // TODO(dual_funding): Take these as input once supported
- let (our_funding_contribution, our_funding_contribution_sats) = (SignedAmount::ZERO, 0u64);
- let our_funding_inputs = Vec::new();
+ debug_assert!(our_funding_contribution <= Amount::MAX_MONEY);
+ let our_funding_contribution_sats = our_funding_contribution.to_sat();
 
  let channel_value_satoshis =
  our_funding_contribution_sats.saturating_add(msg.common_fields.funding_satoshis);
@@ -14161,39 +14176,33 @@ where
  &funding.get_counterparty_pubkeys().revocation_basepoint);
  context.channel_id = channel_id;
 
+ let funding_tx_locktime = LockTime::from_consensus(msg.locktime);
  let funding_negotiation_context = FundingNegotiationContext {
  is_initiator: false,
- our_funding_contribution,
- funding_tx_locktime: LockTime::from_consensus(msg.locktime),
+ our_funding_contribution: our_funding_contribution
+ .to_signed()
+ .expect("our_funding_contribution should not be greater than Amount::MAX_MONEY"),
+ funding_tx_locktime,
  funding_feerate_sat_per_1000_weight: msg.funding_feerate_sat_per_1000_weight,
  shared_funding_input: None,
  our_funding_inputs: our_funding_inputs.clone(),
  our_funding_outputs: Vec::new(),
- change_script: None,
- };
- let shared_funding_output = TxOut {
- value: Amount::from_sat(funding.get_value_satoshis()),
- script_pubkey: funding.get_funding_redeemscript().to_p2wsh(),
+ change_script,
  };
 
- let interactive_tx_constructor = Some(InteractiveTxConstructor::new(
- InteractiveTxConstructorArgs {
+ let mut interactive_tx_constructor = funding_negotiation_context
+ .into_interactive_tx_constructor(
+ &context,
+ &funding,
+ signer_provider,
  entropy_source,
  holder_node_id,
- counterparty_node_id,
- channel_id: context.channel_id,
- feerate_sat_per_kw: funding_negotiation_context.funding_feerate_sat_per_1000_weight,
- funding_tx_locktime: funding_negotiation_context.funding_tx_locktime,
- is_initiator: false,
- inputs_to_contribute: our_funding_inputs,
- shared_funding_input: None,
- shared_funding_output: SharedOwnedOutput::new(shared_funding_output, our_funding_contribution_sats),
- outputs_to_contribute: funding_negotiation_context.our_funding_outputs.clone(),
- }
- ).map_err(|err| {
- let reason = ClosureReason::ProcessingError { err: err.reason.to_string() };
- ChannelError::Close((err.reason.to_string(), reason))
- })?);
+ )
+ .map_err(|err| {
+ let reason = ClosureReason::ProcessingError { err: err.reason.to_string() };
+ ChannelError::Close((err.reason.to_string(), reason))
+ })?;
+ debug_assert!(interactive_tx_constructor.take_initiator_first_message().is_none());
 
  let unfunded_context = UnfundedChannelContext {
  unfunded_channel_age_ticks: 0,
@@ -14202,9 +14211,10 @@ where
  Ok(Self {
  funding,
  context,
- funding_negotiation_context,
- interactive_tx_constructor,
  unfunded_context,
+ funding_tx_locktime,
+ funding_negotiation_context: None,
+ interactive_tx_constructor: Some(interactive_tx_constructor),
  })
 	}
 
@@ -14267,8 +14277,7 @@ where
  }),
  channel_type: Some(self.funding.get_channel_type().clone()),
  },
- funding_satoshis: self.funding_negotiation_context.our_funding_contribution.to_sat()
- as u64,
+ funding_satoshis: self.our_funding_contribution().to_sat(),
  second_per_commitment_point,
  require_confirmed_inputs: None,
  }
@@ -14283,6 +14292,10 @@ where
 	pub fn get_accept_channel_v2_message(&self) -> msgs::AcceptChannelV2 {
  self.generate_accept_channel_v2_message()
 	}
+
+	pub fn our_funding_contribution(&self) -> Amount {
+ Amount::from_sat(self.funding.value_to_self_msat / 1000)
+	}
 }
 
 // Unfunded channel utilities

lightning/src/ln/channelmanager.rs

@@ -30,7 +30,7 @@ use bitcoin::hashes::{Hash, HashEngine, HmacEngine};
 
 use bitcoin::secp256k1::Secp256k1;
 use bitcoin::secp256k1::{PublicKey, SecretKey};
-use bitcoin::{secp256k1, Sequence, SignedAmount};
+use bitcoin::{secp256k1, Amount, ScriptBuf, Sequence};
 
 use crate::blinded_path::message::{
 	AsyncPaymentsContext, BlindedMessagePath, MessageForwardNode, OffersContext,
@@ -65,7 +65,7 @@ use crate::ln::channel::{
 	WithChannelContext,
 };
 use crate::ln::channel_state::ChannelDetails;
-use crate::ln::funding::SpliceContribution;
+use crate::ln::funding::{FundingTxInput, SpliceContribution};
 use crate::ln::inbound_payment;
 use crate::ln::interactivetxs::InteractiveTxMessageSend;
 use crate::ln::msgs;
@@ -9814,6 +9814,9 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
  false,
  user_channel_id,
  config_overrides,
+ Amount::ZERO,
+ vec![],
+ None,
  )
 	}
 
@@ -9845,15 +9848,73 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
  true,
  user_channel_id,
  config_overrides,
+ Amount::ZERO,
+ vec![],
+ None,
+ )
+	}
+
+	/// Accepts a request to open a dual-funded channel with a contribution provided after an
+	/// [`Event::OpenChannelRequest`].
+	///
+	/// The [`Event::OpenChannelRequest::channel_negotiation_type`] field will indicate the open channel
+	/// request is for a dual-funded channel when the variant is [`InboundChannelFunds::DualFunded`].
+	///
+	/// The `temporary_channel_id` parameter indicates which inbound channel should be accepted,
+	/// and the `counterparty_node_id` parameter is the id of the peer that has requested to open
+	/// the channel.
+	///
+	/// The `user_channel_id` parameter will be provided back in
+	/// [`Event::ChannelClosed::user_channel_id`] to allow tracking of which events correspond
+	/// with which `accept_inbound_channel_*` call.
+	///
+	/// The `funding_inputs` parameter provides which UTXOs to use for `our_funding_contribution`
+	/// along with the corresponding satisfaction weight. They must be able to cover any fees needed
+	/// to pay for the contributed weight to the funding transaction. This includes the witnesses
+	/// provided through calling [`ChannelManager::funding_transaction_signed`] after receiving
+	/// [`Event::FundingTransactionReadyForSigning`].
+	///
+	/// Note that this method will return an error and reject the channel if it requires support for
+	/// zero confirmations.
+	// TODO(dual_funding): Discussion on complications with 0conf dual-funded channels where "locking"
+	// of UTXOs used for funding would be required and other issues.
+	// See https://diyhpl.us/~bryan/irc/bitcoin/bitcoin-dev/linuxfoundation-pipermail/lightning-dev/2023-May/003922.txt
+	///
+	/// [`Event::OpenChannelRequest`]: events::Event::OpenChannelRequest
+	/// [`Event::OpenChannelRequest::channel_negotiation_type`]: events::Event::OpenChannelRequest::channel_negotiation_type
+	/// [`Event::ChannelClosed::user_channel_id`]: events::Event::ChannelClosed::user_channel_id
+	/// [`Event::FundingTransactionReadyForSigning`]: events::Event::FundingTransactionReadyForSigning
+	/// [`ChannelManager::funding_transaction_signed`]: ChannelManager::funding_transaction_signed
+	pub fn accept_inbound_channel_with_contribution(
+ &self, temporary_channel_id: &ChannelId, counterparty_node_id: &PublicKey,
+ user_channel_id: u128, config_overrides: Option<ChannelConfigOverrides>,
+ our_funding_contribution: Amount, funding_inputs: Vec<FundingTxInput>,
+ change_script: Option<ScriptBuf>,
+	) -> Result<(), APIError> {
+ self.do_accept_inbound_channel(
+ temporary_channel_id,
+ counterparty_node_id,
+ false,
+ user_channel_id,
+ config_overrides,
+ our_funding_contribution,
+ funding_inputs,
+ change_script,
  )
 	}
 
-	/// TODO(dual_funding): Allow contributions, pass intended amount and inputs
 	#[rustfmt::skip]
 	fn do_accept_inbound_channel(
- &self, temporary_channel_id: &ChannelId, counterparty_node_id: &PublicKey, accept_0conf: bool,
- user_channel_id: u128, config_overrides: Option<ChannelConfigOverrides>
+ &self, temporary_channel_id: &ChannelId, counterparty_node_id: &PublicKey,
+ accept_0conf: bool, user_channel_id: u128, config_overrides: Option<ChannelConfigOverrides>,
+ our_funding_contribution: Amount, funding_inputs: Vec<FundingTxInput>,
+ change_script: Option<ScriptBuf>,
 	) -> Result<(), APIError> {
+ if our_funding_contribution > Amount::MAX_MONEY {
+ return Err(APIError::APIMisuseError {
+ err: format!("the funding contribution must be smaller than the total bitcoin supply, it was {}", our_funding_contribution)
+ });
+ }
 
  let mut config = self.config.read().unwrap().clone();
 
@@ -9911,7 +9972,7 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
  &self.channel_type_features(), &peer_state.latest_features,
  &open_channel_msg,
  user_channel_id, &config, best_block_height,
- &self.logger,
+ &self.logger, our_funding_contribution, funding_inputs, change_script,
  ).map_err(|e| {
  let channel_id = open_channel_msg.common_fields.temporary_channel_id;
  MsgHandleErrInternal::from_chan_no_close(e, channel_id)
@@ -10055,7 +10116,7 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
 
  // Inbound V2 channels with contributed inputs are not considered unfunded.
  if let Some(unfunded_chan) = chan.as_unfunded_v2() {
- if unfunded_chan.funding_negotiation_context.our_funding_contribution > SignedAmount::ZERO {
+ if unfunded_chan.our_funding_contribution() > Amount::ZERO {
  continue;
  }
  }
@@ -10197,7 +10258,7 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
  &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, user_channel_id,
- &self.config.read().unwrap(), best_block_height, &self.logger,
+ &self.config.read().unwrap(), best_block_height, &self.logger, Amount::ZERO, vec![], None,
  ).map_err(|e| MsgHandleErrInternal::from_chan_no_close(e, msg.common_fields.temporary_channel_id))?;
  let message_send_event = MessageSendEvent::SendAcceptChannelV2 {
  node_id: *counterparty_node_id,

lightning/src/ln/channel.rs

@@ -6314,6 +6314,19 @@ where
  }
 	}
 
+	#[cfg(all(test))]
+	pub fn get_initial_counterparty_commitment_signatures_for_test<L: Deref>(
+ &mut self, funding: &mut FundingScope, logger: &L,
+ counterparty_next_commitment_point_override: PublicKey,
+	) -> Option<(Signature, Vec<Signature>)>
+	where
+ SP::Target: SignerProvider,
+ L::Target: Logger,
+	{
+ self.counterparty_next_commitment_point = Some(counterparty_next_commitment_point_override);
+ self.get_initial_counterparty_commitment_signatures(funding, logger)
+	}
+
 	fn check_funding_meets_minimum_depth(&self, funding: &FundingScope, height: u32) -> bool {
  let minimum_depth = self
  .minimum_depth(funding)
@@ -13946,7 +13959,9 @@ where
 	pub funding: FundingScope,
 	pub context: ChannelContext<SP>,
 	pub unfunded_context: UnfundedChannelContext,
-	pub funding_negotiation_context: FundingNegotiationContext,
+	funding_tx_locktime: LockTime,
+	#[allow(unused)] // TODO(dual_funding): Remove once initiating V2 channels is enabled.
+	pub funding_negotiation_context: Option<FundingNegotiationContext>,
 	/// The current interactive transaction construction session under negotiation.
 	pub interactive_tx_constructor: Option<InteractiveTxConstructor>,
 }
@@ -14021,7 +14036,8 @@ where
  funding,
  context,
  unfunded_context,
- funding_negotiation_context,
+ funding_tx_locktime,
+ funding_negotiation_context: Some(funding_negotiation_context),
  interactive_tx_constructor: None,
  };
  Ok(chan)
@@ -14096,29 +14112,28 @@ where
  },
  funding_feerate_sat_per_1000_weight: self.context.feerate_per_kw,
  second_per_commitment_point,
- locktime: self.funding_negotiation_context.funding_tx_locktime.to_consensus_u32(),
+ locktime: self.funding_tx_locktime.to_consensus_u32(),
  require_confirmed_inputs: None,
  }
 	}
 
 	/// 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!
-	/// TODO(dual_funding): Allow contributions, pass intended amount and inputs
 	#[allow(dead_code)] // TODO(dual_funding): Remove once V2 channels is enabled.
 	#[rustfmt::skip]
 	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,
- user_id: u128, config: &UserConfig, current_chain_height: u32, logger: &L,
+ their_features: &InitFeatures, msg: &msgs::OpenChannelV2, user_id: u128, config: &UserConfig,
+ current_chain_height: u32, logger: &L, our_funding_contribution: Amount,
+ our_funding_inputs: Vec<FundingTxInput>, change_script: Option<ScriptBuf>,
 	) -> Result<Self, ChannelError>
  where ES::Target: EntropySource,
  F::Target: FeeEstimator,
  L::Target: Logger,
 	{
- // TODO(dual_funding): Take these as input once supported
- let (our_funding_contribution, our_funding_contribution_sats) = (SignedAmount::ZERO, 0u64);
- let our_funding_inputs = Vec::new();
+ debug_assert!(our_funding_contribution <= Amount::MAX_MONEY);
+ let our_funding_contribution_sats = our_funding_contribution.to_sat();
 
  let channel_value_satoshis =
  our_funding_contribution_sats.saturating_add(msg.common_fields.funding_satoshis);
@@ -14161,39 +14176,33 @@ where
  &funding.get_counterparty_pubkeys().revocation_basepoint);
  context.channel_id = channel_id;
 
+ let funding_tx_locktime = LockTime::from_consensus(msg.locktime);
  let funding_negotiation_context = FundingNegotiationContext {
  is_initiator: false,
- our_funding_contribution,
- funding_tx_locktime: LockTime::from_consensus(msg.locktime),
+ our_funding_contribution: our_funding_contribution
+ .to_signed()
+ .expect("our_funding_contribution should not be greater than Amount::MAX_MONEY"),
+ funding_tx_locktime,
  funding_feerate_sat_per_1000_weight: msg.funding_feerate_sat_per_1000_weight,
  shared_funding_input: None,
  our_funding_inputs: our_funding_inputs.clone(),
  our_funding_outputs: Vec::new(),
- change_script: None,
- };
- let shared_funding_output = TxOut {
- value: Amount::from_sat(funding.get_value_satoshis()),
- script_pubkey: funding.get_funding_redeemscript().to_p2wsh(),
+ change_script,
  };
 
- let interactive_tx_constructor = Some(InteractiveTxConstructor::new(
- InteractiveTxConstructorArgs {
+ let mut interactive_tx_constructor = funding_negotiation_context
+ .into_interactive_tx_constructor(
+ &context,
+ &funding,
+ signer_provider,
  entropy_source,
  holder_node_id,
- counterparty_node_id,
- channel_id: context.channel_id,
- feerate_sat_per_kw: funding_negotiation_context.funding_feerate_sat_per_1000_weight,
- funding_tx_locktime: funding_negotiation_context.funding_tx_locktime,
- is_initiator: false,
- inputs_to_contribute: our_funding_inputs,
- shared_funding_input: None,
- shared_funding_output: SharedOwnedOutput::new(shared_funding_output, our_funding_contribution_sats),
- outputs_to_contribute: funding_negotiation_context.our_funding_outputs.clone(),
- }
- ).map_err(|err| {
- let reason = ClosureReason::ProcessingError { err: err.reason.to_string() };
- ChannelError::Close((err.reason.to_string(), reason))
- })?);
+ )
+ .map_err(|err| {
+ let reason = ClosureReason::ProcessingError { err: err.reason.to_string() };
+ ChannelError::Close((err.reason.to_string(), reason))
+ })?;
+ debug_assert!(interactive_tx_constructor.take_initiator_first_message().is_none());
 
  let unfunded_context = UnfundedChannelContext {
  unfunded_channel_age_ticks: 0,
@@ -14202,9 +14211,10 @@ where
  Ok(Self {
  funding,
  context,
- funding_negotiation_context,
- interactive_tx_constructor,
  unfunded_context,
+ funding_tx_locktime,
+ funding_negotiation_context: None,
+ interactive_tx_constructor: Some(interactive_tx_constructor),
  })
 	}
 
@@ -14267,8 +14277,7 @@ where
  }),
  channel_type: Some(self.funding.get_channel_type().clone()),
  },
- funding_satoshis: self.funding_negotiation_context.our_funding_contribution.to_sat()
- as u64,
+ funding_satoshis: self.our_funding_contribution().to_sat(),
  second_per_commitment_point,
  require_confirmed_inputs: None,
  }
@@ -14283,6 +14292,10 @@ where
 	pub fn get_accept_channel_v2_message(&self) -> msgs::AcceptChannelV2 {
  self.generate_accept_channel_v2_message()
 	}
+
+	pub fn our_funding_contribution(&self) -> Amount {
+ Amount::from_sat(self.funding.value_to_self_msat / 1000)
+	}
 }
 
 // Unfunded channel utilities

lightning/src/ln/channelmanager.rs

@@ -30,7 +30,7 @@ use bitcoin::hashes::{Hash, HashEngine, HmacEngine};
 
 use bitcoin::secp256k1::Secp256k1;
 use bitcoin::secp256k1::{PublicKey, SecretKey};
-use bitcoin::{secp256k1, Sequence, SignedAmount};
+use bitcoin::{secp256k1, Amount, ScriptBuf, Sequence};
 
 use crate::blinded_path::message::{
 	AsyncPaymentsContext, BlindedMessagePath, MessageForwardNode, OffersContext,
@@ -65,7 +65,7 @@ use crate::ln::channel::{
 	WithChannelContext,
 };
 use crate::ln::channel_state::ChannelDetails;
-use crate::ln::funding::SpliceContribution;
+use crate::ln::funding::{FundingTxInput, SpliceContribution};
 use crate::ln::inbound_payment;
 use crate::ln::interactivetxs::InteractiveTxMessageSend;
 use crate::ln::msgs;
@@ -9814,6 +9814,9 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
  false,
  user_channel_id,
  config_overrides,
+ Amount::ZERO,
+ vec![],
+ None,
  )
 	}
 
@@ -9845,15 +9848,73 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
  true,
  user_channel_id,
  config_overrides,
+ Amount::ZERO,
+ vec![],
+ None,
+ )
+	}
+
+	/// Accepts a request to open a dual-funded channel with a contribution provided after an
+	/// [`Event::OpenChannelRequest`].
+	///
+	/// The [`Event::OpenChannelRequest::channel_negotiation_type`] field will indicate the open channel
+	/// request is for a dual-funded channel when the variant is [`InboundChannelFunds::DualFunded`].
+	///
+	/// The `temporary_channel_id` parameter indicates which inbound channel should be accepted,
+	/// and the `counterparty_node_id` parameter is the id of the peer that has requested to open
+	/// the channel.
+	///
+	/// The `user_channel_id` parameter will be provided back in
+	/// [`Event::ChannelClosed::user_channel_id`] to allow tracking of which events correspond
+	/// with which `accept_inbound_channel_*` call.
+	///
+	/// The `funding_inputs` parameter provides which UTXOs to use for `our_funding_contribution`
+	/// along with the corresponding satisfaction weight. They must be able to cover any fees needed
+	/// to pay for the contributed weight to the funding transaction. This includes the witnesses
+	/// provided through calling [`ChannelManager::funding_transaction_signed`] after receiving
+	/// [`Event::FundingTransactionReadyForSigning`].
+	///
+	/// Note that this method will return an error and reject the channel if it requires support for
+	/// zero confirmations.
+	// TODO(dual_funding): Discussion on complications with 0conf dual-funded channels where "locking"
+	// of UTXOs used for funding would be required and other issues.
+	// See https://diyhpl.us/~bryan/irc/bitcoin/bitcoin-dev/linuxfoundation-pipermail/lightning-dev/2023-May/003922.txt
+	///
+	/// [`Event::OpenChannelRequest`]: events::Event::OpenChannelRequest
+	/// [`Event::OpenChannelRequest::channel_negotiation_type`]: events::Event::OpenChannelRequest::channel_negotiation_type
+	/// [`Event::ChannelClosed::user_channel_id`]: events::Event::ChannelClosed::user_channel_id
+	/// [`Event::FundingTransactionReadyForSigning`]: events::Event::FundingTransactionReadyForSigning
+	/// [`ChannelManager::funding_transaction_signed`]: ChannelManager::funding_transaction_signed
+	pub fn accept_inbound_channel_with_contribution(
+ &self, temporary_channel_id: &ChannelId, counterparty_node_id: &PublicKey,
+ user_channel_id: u128, config_overrides: Option<ChannelConfigOverrides>,
+ our_funding_contribution: Amount, funding_inputs: Vec<FundingTxInput>,
+ change_script: Option<ScriptBuf>,
+	) -> Result<(), APIError> {
+ self.do_accept_inbound_channel(
+ temporary_channel_id,
+ counterparty_node_id,
+ false,
+ user_channel_id,
+ config_overrides,
+ our_funding_contribution,
+ funding_inputs,
+ change_script,
  )
 	}
 
-	/// TODO(dual_funding): Allow contributions, pass intended amount and inputs
 	#[rustfmt::skip]
 	fn do_accept_inbound_channel(
- &self, temporary_channel_id: &ChannelId, counterparty_node_id: &PublicKey, accept_0conf: bool,
- user_channel_id: u128, config_overrides: Option<ChannelConfigOverrides>
+ &self, temporary_channel_id: &ChannelId, counterparty_node_id: &PublicKey,
+ accept_0conf: bool, user_channel_id: u128, config_overrides: Option<ChannelConfigOverrides>,
+ our_funding_contribution: Amount, funding_inputs: Vec<FundingTxInput>,
+ change_script: Option<ScriptBuf>,
 	) -> Result<(), APIError> {
+ if our_funding_contribution > Amount::MAX_MONEY {
+ return Err(APIError::APIMisuseError {
+ err: format!("the funding contribution must be smaller than the total bitcoin supply, it was {}", our_funding_contribution)
+ });
+ }
 
  let mut config = self.config.read().unwrap().clone();
 
@@ -9911,7 +9972,7 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
  &self.channel_type_features(), &peer_state.latest_features,
  &open_channel_msg,
  user_channel_id, &config, best_block_height,
- &self.logger,
+ &self.logger, our_funding_contribution, funding_inputs, change_script,
  ).map_err(|e| {
  let channel_id = open_channel_msg.common_fields.temporary_channel_id;
  MsgHandleErrInternal::from_chan_no_close(e, channel_id)
@@ -10055,7 +10116,7 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
 
  // Inbound V2 channels with contributed inputs are not considered unfunded.
  if let Some(unfunded_chan) = chan.as_unfunded_v2() {
- if unfunded_chan.funding_negotiation_context.our_funding_contribution > SignedAmount::ZERO {
+ if unfunded_chan.our_funding_contribution() > Amount::ZERO {
  continue;
  }
  }
@@ -10197,7 +10258,7 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
  &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, user_channel_id,
- &self.config.read().unwrap(), best_block_height, &self.logger,
+ &self.config.read().unwrap(), best_block_height, &self.logger, Amount::ZERO, vec![], None,
  ).map_err(|e| MsgHandleErrInternal::from_chan_no_close(e, msg.common_fields.temporary_channel_id))?;
  let message_send_event = MessageSendEvent::SendAcceptChannelV2 {
  node_id: *counterparty_node_id,