Merge pull request #598 from TheBlueMatt/2020-04-559-cleanups

Clean up ChannelKeys API

Author: TheBlueMatt

lightning/src/chain/keysinterface.rs

@@ -25,7 +25,6 @@ use util::ser::{Writeable, Writer, Readable};
 
 use ln::chan_utils;
 use ln::chan_utils::{TxCreationKeys, HTLCOutputInCommitment, make_funding_redeemscript, ChannelPublicKeys, LocalCommitmentTransaction};
-use ln::channelmanager::PaymentPreimage;
 use ln::msgs;
 
 use std::sync::Arc;
@@ -185,11 +184,11 @@ pub trait KeysInterface: Send + Sync {
 /// Readable/Writable to serialize out a unique reference to this set of keys so
 /// that you can serialize the full ChannelManager object.
 ///
-/// (TODO: We shouldn't require that, and should have an API to get them at deser time, due mostly
-/// to the possibility of reentrancy issues by calling the user's code during our deserialization
-/// routine).
-/// TODO: We should remove Clone by instead requesting a new ChannelKeys copy when we create
-/// ChannelMonitors instead of expecting to clone the one out of the Channel into the monitors.
+// (TODO: We shouldn't require that, and should have an API to get them at deser time, due mostly
+// to the possibility of reentrancy issues by calling the user's code during our deserialization
+// routine).
+// TODO: We should remove Clone by instead requesting a new ChannelKeys copy when we create
+// ChannelMonitors instead of expecting to clone the one out of the Channel into the monitors.
 pub trait ChannelKeys : Send+Clone {
 	/// Gets the private key for the anchor tx
 	fn funding_key<'a>(&'a self) -> &'a SecretKey;
@@ -210,32 +209,42 @@ pub trait ChannelKeys : Send+Clone {
 	/// Create a signature for a remote commitment transaction and associated HTLC transactions.
 	///
 	/// Note that if signing fails or is rejected, the channel will be force-closed.
-	///
-	/// TODO: Document the things someone using this interface should enforce before signing.
-	/// TODO: Add more input vars to enable better checking (preferably removing commitment_tx and
-	/// making the callee generate it via some util function we expose)!
+	//
+	// TODO: Document the things someone using this interface should enforce before signing.
+	// TODO: Add more input vars to enable better checking (preferably removing commitment_tx and
+	// making the callee generate it via some util function we expose)!
 	fn sign_remote_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, feerate_per_kw: u64, commitment_tx: &Transaction, keys: &TxCreationKeys, htlcs: &[&HTLCOutputInCommitment], to_self_delay: u16, secp_ctx: &Secp256k1<T>) -> Result<(Signature, Vec<Signature>), ()>;
 
-	/// Create a signature for a local commitment transaction
-	///
-	/// TODO: Document the things someone using this interface should enforce before signing.
-	/// TODO: Add more input vars to enable better checking (preferably removing commitment_tx and
-	/// TODO: Ensure test-only version doesn't enforce uniqueness of signature when it's enforced in this method
-	/// making the callee generate it via some util function we expose)!
-	fn sign_local_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, local_commitment_tx: &mut LocalCommitmentTransaction, secp_ctx: &Secp256k1<T>);
+	/// Create a signature for a local commitment transaction. This will only ever be called with
+	/// the same local_commitment_tx (or a copy thereof), though there are currently no guarantees
+	/// that it will not be called multiple times.
+	//
+	// TODO: Document the things someone using this interface should enforce before signing.
+	// TODO: Add more input vars to enable better checking (preferably removing commitment_tx and
+	fn sign_local_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, local_commitment_tx: &LocalCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
+
+	/// Same as sign_local_commitment, but exists only for tests to get access to local commitment
+	/// transactions which will be broadcasted later, after the channel has moved on to a newer
+	/// state. Thus, needs its own method as sign_local_commitment may enforce that we only ever
+	/// get called once.
+	#[cfg(test)]
+	fn unsafe_sign_local_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, local_commitment_tx: &LocalCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
 
-	/// Create a signature for a local commitment transaction without enforcing one-time signing.
+	/// Create a signature for each HTLC transaction spending a local commitment transaction.
 	///
-	/// Testing revocation logic by our test framework needs to sign multiple local commitment
-	/// transactions. This unsafe test-only version doesn't enforce one-time signing security
-	/// requirement.
-	#[cfg(test)]
-	fn unsafe_sign_local_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, local_commitment_tx: &mut LocalCommitmentTransaction, secp_ctx: &Secp256k1<T>);
+	/// Unlike sign_local_commitment, this may be called multiple times with *different*
+	/// local_commitment_tx values. While this will never be called with a revoked
+	/// local_commitment_tx, it is possible that it is called with the second-latest
+	/// local_commitment_tx (only if we haven't yet revoked it) if some watchtower/secondary
+	/// ChannelMonitor decided to broadcast before it had been updated to the latest.
+	///
+	/// Either an Err should be returned, or a Vec with one entry for each HTLC which exists in
+	/// local_commitment_tx. For those HTLCs which have transaction_output_index set to None
+	/// (implying they were considered dust at the time the commitment transaction was negotiated),
+	/// a corresponding None should be included in the return value. All other positions in the
+	/// return value must contain a signature.
+	fn sign_local_commitment_htlc_transactions<T: secp256k1::Signing + secp256k1::Verification>(&self, local_commitment_tx: &LocalCommitmentTransaction, local_csv: u16, secp_ctx: &Secp256k1<T>) -> Result<Vec<Option<Signature>>, ()>;
 
-	/// Signs a transaction created by build_htlc_transaction. If the transaction is an
-	/// HTLC-Success transaction, preimage must be set!
-	/// TODO: should be merged with sign_local_commitment as a slice of HTLC transactions to sign
-	fn sign_htlc_transaction<T: secp256k1::Signing>(&self, local_commitment_tx: &mut LocalCommitmentTransaction, htlc_index: u32, preimage: Option<PaymentPreimage>, local_csv: u16, secp_ctx: &Secp256k1<T>);
 	/// Create a signature for a (proposed) closing transaction.
 	///
 	/// Note that, due to rounding, there may be one "missing" satoshi, and either party may have
@@ -363,25 +372,25 @@ impl ChannelKeys for InMemoryChannelKeys {
 		Ok((commitment_sig, htlc_sigs))
 	}
 
-	fn sign_local_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, local_commitment_tx: &mut LocalCommitmentTransaction, secp_ctx: &Secp256k1<T>) {
+	fn sign_local_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, local_commitment_tx: &LocalCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
 		let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
 		let remote_channel_pubkeys = self.remote_channel_pubkeys.as_ref().expect("must set remote channel pubkeys before signing");
 		let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &remote_channel_pubkeys.funding_pubkey);
 
-		local_commitment_tx.add_local_sig(&self.funding_key, &channel_funding_redeemscript, self.channel_value_satoshis, secp_ctx);
+		Ok(local_commitment_tx.get_local_sig(&self.funding_key, &channel_funding_redeemscript, self.channel_value_satoshis, secp_ctx))
 	}
 
 	#[cfg(test)]
-	fn unsafe_sign_local_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, local_commitment_tx: &mut LocalCommitmentTransaction, secp_ctx: &Secp256k1<T>) {
+	fn unsafe_sign_local_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, local_commitment_tx: &LocalCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
 		let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
 		let remote_channel_pubkeys = self.remote_channel_pubkeys.as_ref().expect("must set remote channel pubkeys before signing");
 		let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &remote_channel_pubkeys.funding_pubkey);
 
-		local_commitment_tx.add_local_sig(&self.funding_key, &channel_funding_redeemscript, self.channel_value_satoshis, secp_ctx);
+		Ok(local_commitment_tx.get_local_sig(&self.funding_key, &channel_funding_redeemscript, self.channel_value_satoshis, secp_ctx))
 	}
 
-	fn sign_htlc_transaction<T: secp256k1::Signing>(&self, local_commitment_tx: &mut LocalCommitmentTransaction, htlc_index: u32, preimage: Option<PaymentPreimage>, local_csv: u16, secp_ctx: &Secp256k1<T>) {
-		local_commitment_tx.add_htlc_sig(&self.htlc_base_key, htlc_index, preimage, local_csv, secp_ctx);
+	fn sign_local_commitment_htlc_transactions<T: secp256k1::Signing + secp256k1::Verification>(&self, local_commitment_tx: &LocalCommitmentTransaction, local_csv: u16, secp_ctx: &Secp256k1<T>) -> Result<Vec<Option<Signature>>, ()> {
+		local_commitment_tx.get_htlc_sigs(&self.htlc_base_key, local_csv, secp_ctx)
 	}
 
 	fn sign_closing_transaction<T: secp256k1::Signing>(&self, closing_tx: &Transaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {