Batch-sign local HTLC txn with a well-doc'd API, returning sigs
[rust-lightning] / lightning / src / chain / keysinterface.rs
index e2e4403b528997e7a4ce56fb2a4591af85631efa..44f347abc12e133ec8d735daf1e9de6a3ce15f87 100644 (file)
@@ -24,7 +24,7 @@ use util::logger::Logger;
 use util::ser::{Writeable, Writer, Readable};
 
 use ln::chan_utils;
-use ln::chan_utils::{TxCreationKeys, HTLCOutputInCommitment, make_funding_redeemscript, ChannelPublicKeys};
+use ln::chan_utils::{TxCreationKeys, HTLCOutputInCommitment, make_funding_redeemscript, ChannelPublicKeys, LocalCommitmentTransaction};
 use ln::msgs;
 
 use std::sync::Arc;
@@ -37,6 +37,7 @@ use ln::msgs::DecodeError;
 /// spend on-chain. The information needed to do this is provided in this enum, including the
 /// outpoint describing which txid and output index is available, the full output which exists at
 /// that txid/index, and any keys or other information required to sign.
+#[derive(Clone, PartialEq)]
 pub enum SpendableOutputDescriptor {
        /// An output to a script which was provided via KeysInterface, thus you should already know
        /// how to spend it. No keys are provided as rust-lightning was never given any keys - only the
@@ -53,7 +54,7 @@ pub enum SpendableOutputDescriptor {
        /// The private key which should be used to sign the transaction is provided, as well as the
        /// full witness redeemScript which is hashed in the output script_pubkey.
        /// The witness in the spending input should be:
-       /// <BIP 143 signature generated with the given key> <one zero byte aka OP_0>
+       /// <BIP 143 signature generated with the given key> <empty vector> (MINIMALIF standard rule)
        /// <witness_script as provided>
        /// Note that the nSequence field in the input must be set to_self_delay (which corresponds to
        /// the transaction not being broadcastable until at least to_self_delay blocks after the input
@@ -88,6 +89,57 @@ pub enum SpendableOutputDescriptor {
        }
 }
 
+impl Writeable for SpendableOutputDescriptor {
+       fn write<W: Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
+               match self {
+                       &SpendableOutputDescriptor::StaticOutput { ref outpoint, ref output } => {
+                               0u8.write(writer)?;
+                               outpoint.write(writer)?;
+                               output.write(writer)?;
+                       },
+                       &SpendableOutputDescriptor::DynamicOutputP2WSH { ref outpoint, ref key, ref witness_script, ref to_self_delay, ref output } => {
+                               1u8.write(writer)?;
+                               outpoint.write(writer)?;
+                               key.write(writer)?;
+                               witness_script.write(writer)?;
+                               to_self_delay.write(writer)?;
+                               output.write(writer)?;
+                       },
+                       &SpendableOutputDescriptor::DynamicOutputP2WPKH { ref outpoint, ref key, ref output } => {
+                               2u8.write(writer)?;
+                               outpoint.write(writer)?;
+                               key.write(writer)?;
+                               output.write(writer)?;
+                       },
+               }
+               Ok(())
+       }
+}
+
+impl Readable for SpendableOutputDescriptor {
+       fn read<R: ::std::io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
+               match Readable::read(reader)? {
+                       0u8 => Ok(SpendableOutputDescriptor::StaticOutput {
+                               outpoint: Readable::read(reader)?,
+                               output: Readable::read(reader)?,
+                       }),
+                       1u8 => Ok(SpendableOutputDescriptor::DynamicOutputP2WSH {
+                               outpoint: Readable::read(reader)?,
+                               key: Readable::read(reader)?,
+                               witness_script: Readable::read(reader)?,
+                               to_self_delay: Readable::read(reader)?,
+                               output: Readable::read(reader)?,
+                       }),
+                       2u8 => Ok(SpendableOutputDescriptor::DynamicOutputP2WPKH {
+                               outpoint: Readable::read(reader)?,
+                               key: Readable::read(reader)?,
+                               output: Readable::read(reader)?,
+                       }),
+                       _ => Err(DecodeError::InvalidValue),
+               }
+       }
+}
+
 /// A trait to describe an object which can get user secrets and key material.
 pub trait KeysInterface: Send + Sync {
        /// A type which implements ChannelKeys which will be returned by get_channel_keys.
@@ -163,6 +215,36 @@ 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. 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 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
@@ -290,6 +372,27 @@ impl ChannelKeys for InMemoryChannelKeys {
                Ok((commitment_sig, htlc_sigs))
        }
 
+       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);
+
+               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: &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);
+
+               Ok(local_commitment_tx.get_local_sig(&self.funding_key, &channel_funding_redeemscript, self.channel_value_satoshis, 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, ()> {
                if closing_tx.input.len() != 1 { return Err(()); }
                if closing_tx.input[0].witness.len() != 0 { return Err(()); }
@@ -330,8 +433,8 @@ impl Writeable for InMemoryChannelKeys {
        }
 }
 
-impl<R: ::std::io::Read> Readable<R> for InMemoryChannelKeys {
-       fn read(reader: &mut R) -> Result<Self, DecodeError> {
+impl Readable for InMemoryChannelKeys {
+       fn read<R: ::std::io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
                let funding_key = Readable::read(reader)?;
                let revocation_base_key = Readable::read(reader)?;
                let payment_base_key = Readable::read(reader)?;
@@ -534,6 +637,6 @@ impl KeysInterface for KeysManager {
                let child_privkey = self.channel_id_master_key.ckd_priv(&self.secp_ctx, ChildNumber::from_hardened_idx(child_ix as u32).expect("key space exhausted")).expect("Your RNG is busted");
                sha.input(&child_privkey.private_key.key[..]);
 
-               (Sha256::from_engine(sha).into_inner())
+               Sha256::from_engine(sha).into_inner()
        }
 }