Batch-sign local HTLC txn with a well-doc'd API, returning sigs

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

diff --git a/lightning/src/chain/keysinterface.rs b/lightning/src/chain/keysinterface.rs
index 03774884400a7e3492b282f6c1362daf34c4de95..44f347abc12e133ec8d735daf1e9de6a3ce15f87 100644 (file)
--- a/lightning/src/chain/keysinterface.rs
+++ b/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;
@@ -231,10 +230,21 @@ pub trait ChannelKeys : Send+Clone {
        #[cfg(test)]
        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!
-       /// 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 each HTLC transaction spending a local commitment transaction.
+       ///
+       /// 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>>, ()>;
+
        /// Create a signature for a (proposed) closing transaction.
        ///
        /// Note that, due to rounding, there may be one "missing" satoshi, and either party may have
@@ -379,8 +389,8 @@ impl ChannelKeys for InMemoryChannelKeys {
                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, ()> {