Introduce DynSigner, a dynamically dispatched signer

DynSigner provides an abstraction for specifying an external signer
for functional tests.

lightning/src/sign/ecdsa.rs

@@ -84,7 +84,7 @@ pub trait EcdsaChannelSigner: ChannelSigner {
 	/// only ever get called once.
 	///
 	/// This method is *not* async as it is intended only for testing purposes.
-	#[cfg(any(test, feature = "unsafe_revoked_tx_signing"))]
+	#[cfg(any(test, feature = "_test_utils", feature = "unsafe_revoked_tx_signing"))]
 	fn unsafe_sign_holder_commitment(
 		&self, channel_parameters: &ChannelTransactionParameters,
 		commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<secp256k1::All>,

lightning/src/sign/mod.rs

@@ -31,7 +31,6 @@ use bitcoin::hashes::{Hash, HashEngine};
 use bitcoin::secp256k1::ecdh::SharedSecret;
 use bitcoin::secp256k1::ecdsa::{RecoverableSignature, Signature};
 use bitcoin::secp256k1::schnorr;
-#[cfg(taproot)]
 use bitcoin::secp256k1::All;
 use bitcoin::secp256k1::{Keypair, PublicKey, Scalar, Secp256k1, SecretKey, Signing};
 use bitcoin::{secp256k1, Psbt, Sequence, Txid, WPubkeyHash, Witness};
@@ -898,10 +897,10 @@ pub trait OutputSpender {
 	/// Returns `Err(())` if the output value is greater than the input value minus required fee,
 	/// if a descriptor was duplicated, or if an output descriptor `script_pubkey`
 	/// does not match the one we can spend.
-	fn spend_spendable_outputs<C: Signing>(
+	fn spend_spendable_outputs(
 		&self, descriptors: &[&SpendableOutputDescriptor], outputs: Vec<TxOut>,
 		change_destination_script: ScriptBuf, feerate_sat_per_1000_weight: u32,
-		locktime: Option<LockTime>, secp_ctx: &Secp256k1<C>,
+		locktime: Option<LockTime>, secp_ctx: &Secp256k1<All>,
 	) -> Result<Transaction, ()>;
 }
 
@@ -1351,7 +1350,7 @@ impl EcdsaChannelSigner for InMemorySigner {
 		))
 	}
 
-	#[cfg(any(test, feature = "unsafe_revoked_tx_signing"))]
+	#[cfg(any(test, feature = "_test_utils", feature = "unsafe_revoked_tx_signing"))]
 	fn unsafe_sign_holder_commitment(
 		&self, channel_parameters: &ChannelTransactionParameters,
 		commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<secp256k1::All>,
@@ -2044,10 +2043,10 @@ impl OutputSpender for KeysManager {
 	///
 	/// May panic if the [`SpendableOutputDescriptor`]s were not generated by channels which used
 	/// this [`KeysManager`] or one of the [`InMemorySigner`] created by this [`KeysManager`].
-	fn spend_spendable_outputs<C: Signing>(
+	fn spend_spendable_outputs(
 		&self, descriptors: &[&SpendableOutputDescriptor], outputs: Vec<TxOut>,
 		change_destination_script: ScriptBuf, feerate_sat_per_1000_weight: u32,
-		locktime: Option<LockTime>, secp_ctx: &Secp256k1<C>,
+		locktime: Option<LockTime>, secp_ctx: &Secp256k1<All>,
 	) -> Result<Transaction, ()> {
 		let (mut psbt, expected_max_weight) =
 			SpendableOutputDescriptor::create_spendable_outputs_psbt(
@@ -2194,10 +2193,10 @@ impl NodeSigner for PhantomKeysManager {
 impl OutputSpender for PhantomKeysManager {
 	/// See [`OutputSpender::spend_spendable_outputs`] and [`KeysManager::spend_spendable_outputs`]
 	/// for documentation on this method.
-	fn spend_spendable_outputs<C: Signing>(
+	fn spend_spendable_outputs(
 		&self, descriptors: &[&SpendableOutputDescriptor], outputs: Vec<TxOut>,
 		change_destination_script: ScriptBuf, feerate_sat_per_1000_weight: u32,
-		locktime: Option<LockTime>, secp_ctx: &Secp256k1<C>,
+		locktime: Option<LockTime>, secp_ctx: &Secp256k1<All>,
 	) -> Result<Transaction, ()> {
 		self.inner.spend_spendable_outputs(
 			descriptors,

lightning/src/util/dyn_signer.rs

@@ -0,0 +1,330 @@
+//! A dynamically dispatched signer
+
+use crate::prelude::*;
+
+use core::any::Any;
+
+use crate::ln::chan_utils::{
+	ChannelPublicKeys, ChannelTransactionParameters, ClosingTransaction, CommitmentTransaction,
+	HTLCOutputInCommitment, HolderCommitmentTransaction,
+};
+use crate::ln::inbound_payment::ExpandedKey;
+use crate::ln::msgs::{UnsignedChannelAnnouncement, UnsignedGossipMessage};
+use crate::ln::script::ShutdownScript;
+use crate::sign::ecdsa::EcdsaChannelSigner;
+#[cfg(taproot)]
+use crate::sign::taproot::TaprootChannelSigner;
+use crate::sign::ChannelSigner;
+use crate::sign::InMemorySigner;
+use crate::sign::{EntropySource, HTLCDescriptor, OutputSpender, PhantomKeysManager};
+use crate::sign::{NodeSigner, Recipient, SignerProvider, SpendableOutputDescriptor};
+use bitcoin;
+use bitcoin::absolute::LockTime;
+use bitcoin::secp256k1::All;
+use bitcoin::{secp256k1, ScriptBuf, Transaction, TxOut};
+use lightning_invoice::RawBolt11Invoice;
+#[cfg(taproot)]
+use musig2::types::{PartialSignature, PublicNonce};
+use secp256k1::ecdsa::RecoverableSignature;
+use secp256k1::{ecdh::SharedSecret, ecdsa::Signature, PublicKey, Scalar, Secp256k1, SecretKey};
+use types::payment::PaymentPreimage;
+
+#[cfg(not(taproot))]
+/// A super-trait for all the traits that a dyn signer backing implements
+pub trait DynSignerTrait: EcdsaChannelSigner + Send + Sync {}
+
+#[cfg(taproot)]
+/// A super-trait for all the traits that a dyn signer backing implements
+pub trait DynSignerTrait: EcdsaChannelSigner + TaprootChannelSigner + Send + Sync {}
+
+/// Helper to allow DynSigner to clone itself
+pub trait InnerSign: DynSignerTrait {
+	/// Clone into a Box
+	fn box_clone(&self) -> Box<dyn InnerSign>;
+	/// Cast to Any for runtime type checking
+	fn as_any(&self) -> &dyn Any;
+}
+
+/// A ChannelSigner derived struct allowing run-time selection of a signer
+pub struct DynSigner {
+	/// The inner signer
+	pub inner: Box<dyn InnerSign>,
+}
+
+impl DynSigner {
+	/// Create a new DynSigner
+	pub fn new<S: InnerSign + 'static>(inner: S) -> Self {
+		DynSigner { inner: Box::new(inner) }
+	}
+}
+
+#[cfg(taproot)]
+#[allow(unused_variables)]
+impl TaprootChannelSigner for DynSigner {
+	fn generate_local_nonce_pair(
+		&self, commitment_number: u64, secp_ctx: &Secp256k1<All>,
+	) -> PublicNonce {
+		todo!()
+	}
+
+	fn partially_sign_counterparty_commitment(
+		&self, counterparty_nonce: PublicNonce, commitment_tx: &CommitmentTransaction,
+		inbound_htlc_preimages: Vec<PaymentPreimage>,
+		outbound_htlc_preimages: Vec<PaymentPreimage>, secp_ctx: &Secp256k1<All>,
+	) -> Result<(crate::ln::msgs::PartialSignatureWithNonce, Vec<secp256k1::schnorr::Signature>), ()>
+	{
+		todo!();
+	}
+
+	fn finalize_holder_commitment(
+		&self, commitment_tx: &HolderCommitmentTransaction,
+		counterparty_partial_signature: crate::ln::msgs::PartialSignatureWithNonce,
+		secp_ctx: &Secp256k1<All>,
+	) -> Result<PartialSignature, ()> {
+		todo!();
+	}
+
+	fn sign_justice_revoked_output(
+		&self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey,
+		secp_ctx: &Secp256k1<All>,
+	) -> Result<secp256k1::schnorr::Signature, ()> {
+		todo!();
+	}
+
+	fn sign_justice_revoked_htlc(
+		&self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey,
+		htlc: &HTLCOutputInCommitment, secp_ctx: &Secp256k1<All>,
+	) -> Result<secp256k1::schnorr::Signature, ()> {
+		todo!();
+	}
+
+	fn sign_holder_htlc_transaction(
+		&self, htlc_tx: &Transaction, input: usize, htlc_descriptor: &HTLCDescriptor,
+		secp_ctx: &Secp256k1<All>,
+	) -> Result<secp256k1::schnorr::Signature, ()> {
+		todo!();
+	}
+
+	fn sign_counterparty_htlc_transaction(
+		&self, htlc_tx: &Transaction, input: usize, amount: u64, per_commitment_point: &PublicKey,
+		htlc: &HTLCOutputInCommitment, secp_ctx: &Secp256k1<All>,
+	) -> Result<secp256k1::schnorr::Signature, ()> {
+		todo!();
+	}
+
+	fn partially_sign_closing_transaction(
+		&self, closing_tx: &ClosingTransaction, secp_ctx: &Secp256k1<All>,
+	) -> Result<PartialSignature, ()> {
+		todo!();
+	}
+
+	fn sign_holder_anchor_input(
+		&self, anchor_tx: &Transaction, input: usize, secp_ctx: &Secp256k1<All>,
+	) -> Result<secp256k1::schnorr::Signature, ()> {
+		todo!();
+	}
+}
+
+impl Clone for DynSigner {
+	fn clone(&self) -> Self {
+		DynSigner { inner: self.inner.box_clone() }
+	}
+}
+
+delegate!(DynSigner, EcdsaChannelSigner, inner,
+	fn sign_holder_commitment(, channel_parameters: &ChannelTransactionParameters,
+		commitment_tx: &HolderCommitmentTransaction,
+		secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()>,
+	#[cfg(any(test, feature = "_test_utils", feature = "unsafe_revoked_tx_signing"))]
+	fn unsafe_sign_holder_commitment(, channel_parameters: &ChannelTransactionParameters,
+		commitment_tx: &HolderCommitmentTransaction,
+		secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()>,
+	fn sign_counterparty_commitment(, channel_parameters: &ChannelTransactionParameters,
+		commitment_tx: &CommitmentTransaction, inbound_htlc_preimages: Vec<PaymentPreimage>,
+		outbound_htlc_preimages: Vec<PaymentPreimage>,
+		secp_ctx: &Secp256k1<secp256k1::All>) -> Result<(Signature, Vec<Signature>), ()>,
+	fn sign_justice_revoked_output(, channel_parameters: &ChannelTransactionParameters,
+		justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey,
+		secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()>,
+	fn sign_justice_revoked_htlc(, channel_parameters: &ChannelTransactionParameters,
+		justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey,
+		htlc: &HTLCOutputInCommitment, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()>,
+	fn sign_counterparty_htlc_transaction(, channel_parameters: &ChannelTransactionParameters,
+		htlc_tx: &Transaction, input: usize, amount: u64, per_commitment_point: &PublicKey,
+		htlc: &HTLCOutputInCommitment, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()>,
+	fn sign_closing_transaction(, channel_parameters: &ChannelTransactionParameters,
+		closing_tx: &ClosingTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()>,
+	fn sign_channel_announcement_with_funding_key(, msg: &UnsignedChannelAnnouncement,
+		secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()>,
+	fn sign_holder_anchor_input(, channel_parameters: &ChannelTransactionParameters,
+		anchor_tx: &Transaction, input: usize,
+		secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()>,
+	fn sign_holder_htlc_transaction(, htlc_tx: &Transaction, input: usize,
+		htlc_descriptor: &HTLCDescriptor, secp_ctx: &Secp256k1<All>) -> Result<Signature, ()>,
+	fn sign_splicing_funding_input(, channel_parameters: &ChannelTransactionParameters,
+		tx: &Transaction, input_index: usize, input_value: u64,
+		secp_ctx: &Secp256k1<All>) -> Result<Signature, ()>
+);
+
+delegate!(DynSigner, ChannelSigner,
+	inner,
+	fn get_per_commitment_point(,
+		idx: u64,
+		secp_ctx: &Secp256k1<secp256k1::All>
+	) -> Result<PublicKey, ()>,
+	fn release_commitment_secret(, idx: u64) -> Result<[u8; 32], ()>,
+	fn validate_holder_commitment(,
+		holder_tx: &HolderCommitmentTransaction,
+		preimages: Vec<PaymentPreimage>
+	) -> Result<(), ()>,
+	fn pubkeys(,) -> &ChannelPublicKeys,
+	fn channel_keys_id(,) -> [u8; 32],
+	fn validate_counterparty_revocation(, idx: u64, secret: &SecretKey) -> Result<(), ()>
+);
+
+impl DynSignerTrait for InMemorySigner {}
+
+impl InnerSign for InMemorySigner {
+	fn box_clone(&self) -> Box<dyn InnerSign> {
+		Box::new(self.clone())
+	}
+
+	fn as_any(&self) -> &dyn Any {
+		self
+	}
+}
+
+/// A convenience wrapper for DynKeysInterfaceTrait
+pub struct DynKeysInterface {
+	/// The inner dyn keys interface
+	pub inner: Box<dyn DynKeysInterfaceTrait>,
+}
+
+impl DynKeysInterface {
+	/// Create a new DynKeysInterface
+	pub fn new(inner: Box<dyn DynKeysInterfaceTrait>) -> Self {
+		DynKeysInterface { inner }
+	}
+}
+
+delegate!(DynKeysInterface, NodeSigner,
+inner,
+	fn get_node_id(, recipient: Recipient) -> Result<PublicKey, ()>,
+	fn sign_gossip_message(, msg: UnsignedGossipMessage) -> Result<Signature, ()>,
+	fn ecdh(, recipient: Recipient, other_key: &PublicKey, tweak: Option<&Scalar>) -> Result<SharedSecret, ()>,
+	fn sign_invoice(, invoice: &RawBolt11Invoice, recipient: Recipient) -> Result<RecoverableSignature, ()>,
+	fn sign_bolt12_invoice(,
+		invoice: &crate::offers::invoice::UnsignedBolt12Invoice
+	) -> Result<secp256k1::schnorr::Signature, ()>,
+	fn get_inbound_payment_key(,) -> ExpandedKey
+);
+
+delegate!(DynKeysInterface, SignerProvider,
+	inner,
+	fn get_destination_script(, channel_keys_id: [u8; 32]) -> Result<ScriptBuf, ()>,
+	fn get_shutdown_scriptpubkey(,) -> Result<ShutdownScript, ()>,
+	fn generate_channel_keys_id(, _inbound: bool, _user_channel_id: u128) -> [u8; 32],
+	fn derive_channel_signer(, _channel_keys_id: [u8; 32]) -> Self::EcdsaSigner;
+	type EcdsaSigner = DynSigner,
+	#[cfg(taproot)]
+	type TaprootSigner = DynSigner
+);
+
+delegate!(DynKeysInterface, EntropySource, inner,
+	fn get_secure_random_bytes(,) -> [u8; 32]
+);
+
+delegate!(DynKeysInterface, OutputSpender, inner,
+	fn spend_spendable_outputs(,
+		descriptors: &[&SpendableOutputDescriptor], outputs: Vec<TxOut>,
+		change_destination_script: ScriptBuf, feerate_sat_per_1000_weight: u32,
+		locktime: Option<LockTime>, secp_ctx: &Secp256k1<All>
+	) -> Result<Transaction, ()>
+);
+#[cfg(not(taproot))]
+/// A supertrait for all the traits that a keys interface implements
+pub trait DynKeysInterfaceTrait:
+	NodeSigner + OutputSpender + SignerProvider<EcdsaSigner = DynSigner> + EntropySource + Send + Sync
+{
+	#[cfg(test)]
+	fn set_counter(&self, _count: u64) {}
+}
+
+#[cfg(taproot)]
+/// A supertrait for all the traits that a keys interface implements
+pub trait DynKeysInterfaceTrait:
+	NodeSigner
+	+ OutputSpender
+	+ SignerProvider<EcdsaSigner = DynSigner, TaprootSigner = DynSigner>
+	+ EntropySource
+	+ Send
+	+ Sync
+{
+	#[cfg(test)]
+	fn set_counter(&self, _count: u64) {}
+}
+
+/// A dyn wrapper for PhantomKeysManager
+pub struct DynPhantomKeysInterface {
+	inner: Box<PhantomKeysManager>,
+}
+
+impl DynPhantomKeysInterface {
+	/// Create a new DynPhantomKeysInterface
+	pub fn new(inner: PhantomKeysManager) -> Self {
+		DynPhantomKeysInterface { inner: Box::new(inner) }
+	}
+}
+
+delegate!(DynPhantomKeysInterface, NodeSigner,
+	inner,
+	fn get_node_id(, recipient: Recipient) -> Result<PublicKey, ()>,
+	fn sign_gossip_message(, msg: UnsignedGossipMessage) -> Result<Signature, ()>,
+	fn ecdh(, recipient: Recipient, other_key: &PublicKey, tweak: Option<&Scalar>) -> Result<SharedSecret, ()>,
+	fn sign_invoice(, invoice: &RawBolt11Invoice, recipient: Recipient) -> Result<RecoverableSignature, ()>,
+	fn sign_bolt12_invoice(, invoice: &crate::offers::invoice::UnsignedBolt12Invoice
+	) -> Result<secp256k1::schnorr::Signature, ()>,
+	fn get_inbound_payment_key(,) -> ExpandedKey
+);
+
+impl SignerProvider for DynPhantomKeysInterface {
+	type EcdsaSigner = DynSigner;
+	#[cfg(taproot)]
+	type TaprootSigner = DynSigner;
+
+	fn get_destination_script(&self, channel_keys_id: [u8; 32]) -> Result<ScriptBuf, ()> {
+		self.inner.get_destination_script(channel_keys_id)
+	}
+
+	fn get_shutdown_scriptpubkey(&self) -> Result<ShutdownScript, ()> {
+		self.inner.get_shutdown_scriptpubkey()
+	}
+
+	fn generate_channel_keys_id(&self, _inbound: bool, _user_channel_id: u128) -> [u8; 32] {
+		self.inner.generate_channel_keys_id(_inbound, _user_channel_id)
+	}
+
+	fn derive_channel_signer(&self, channel_keys_id: [u8; 32]) -> Self::EcdsaSigner {
+		let inner = self.inner.derive_channel_signer(channel_keys_id);
+		DynSigner::new(inner)
+	}
+}
+
+delegate!(DynPhantomKeysInterface, EntropySource, inner,
+	fn get_secure_random_bytes(,) -> [u8; 32]
+);
+
+delegate!(DynPhantomKeysInterface, OutputSpender, inner,
+	fn spend_spendable_outputs(,
+		descriptors: &[&SpendableOutputDescriptor], outputs: Vec<TxOut>,
+		change_destination_script: ScriptBuf, feerate_sat_per_1000_weight: u32,
+		locktime: Option<LockTime>, secp_ctx: &Secp256k1<All>
+	) -> Result<Transaction, ()>
+);
+
+impl DynKeysInterfaceTrait for DynPhantomKeysInterface {
+	#[cfg(test)]
+	fn set_counter(&self, count: u64) {
+		self.inner.inner.entropy_source.set_counter(count);
+	}
+}