Return Result<Signature> instead of modifying args in ChannelKeys

[rust-lightning] / lightning / src / chain / keysinterface.rs

diff --git a/lightning/src/chain/keysinterface.rs b/lightning/src/chain/keysinterface.rs
index ec76262b15ad026d9d2d6a6a42d85b91554f82db..03774884400a7e3492b282f6c1362daf34c4de95 100644 (file)
--- a/lightning/src/chain/keysinterface.rs
+++ b/lightning/src/chain/keysinterface.rs
@@ -216,21 +216,20 @@ pub trait ChannelKeys : Send+Clone {
        /// 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
+       /// 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
-       /// 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>);
+       fn 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.
-       ///
-       /// 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.
+       /// 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: &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, ()>;
 
        /// Signs a transaction created by build_htlc_transaction. If the transaction is an
        /// HTLC-Success transaction, preimage must be set!
@@ -363,21 +362,21 @@ 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>) {