Merge pull request #461 from TheBlueMatt/2020-08-mut-sighash
Expose the witnesses of the tx being hashed in SigHashCache
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commit
4e737f708a
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@ -25,6 +25,8 @@ use blockdata::script::Script;
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use blockdata::transaction::{Transaction, TxIn, SigHashType};
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use blockdata::transaction::{Transaction, TxIn, SigHashType};
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use consensus::encode::Encodable;
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use consensus::encode::Encodable;
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use std::ops::{Deref, DerefMut};
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/// Parts of a sighash which are common across inputs or signatures, and which are
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/// Parts of a sighash which are common across inputs or signatures, and which are
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/// sufficient (in conjunction with a private key) to sign the transaction
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/// sufficient (in conjunction with a private key) to sign the transaction
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#[derive(Clone, PartialEq, Eq, Debug)]
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#[derive(Clone, PartialEq, Eq, Debug)]
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@ -102,9 +104,9 @@ impl SighashComponents {
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}
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}
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/// A replacement for SigHashComponents which supports all sighash modes
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/// A replacement for SigHashComponents which supports all sighash modes
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pub struct SigHashCache<'a> {
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pub struct SigHashCache<R: Deref<Target=Transaction>> {
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/// Access to transaction required for various introspection
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/// Access to transaction required for various introspection
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tx: &'a Transaction,
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tx: R,
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/// Hash of all the previous outputs, computed as required
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/// Hash of all the previous outputs, computed as required
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hash_prevouts: Option<sha256d::Hash>,
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hash_prevouts: Option<sha256d::Hash>,
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/// Hash of all the input sequence nos, computed as required
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/// Hash of all the input sequence nos, computed as required
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@ -113,12 +115,12 @@ pub struct SigHashCache<'a> {
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hash_outputs: Option<sha256d::Hash>,
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hash_outputs: Option<sha256d::Hash>,
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}
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}
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impl<'a> SigHashCache<'a> {
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impl<R: Deref<Target=Transaction>> SigHashCache<R> {
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/// Compute the sighash components from an unsigned transaction and auxiliary
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/// Compute the sighash components from an unsigned transaction and auxiliary
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/// in a lazy manner when required.
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/// in a lazy manner when required.
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/// For the generated sighashes to be valid, no fields in the transaction may change except for
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/// For the generated sighashes to be valid, no fields in the transaction may change except for
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/// script_sig and witnesses.
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/// script_sig and witnesses.
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pub fn new(tx: &Transaction) -> SigHashCache {
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pub fn new(tx: R) -> Self {
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SigHashCache {
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SigHashCache {
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tx: tx,
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tx: tx,
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hash_prevouts: None,
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hash_prevouts: None,
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@ -189,6 +191,7 @@ impl<'a> SigHashCache<'a> {
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zero_hash.consensus_encode(&mut enc).unwrap();
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zero_hash.consensus_encode(&mut enc).unwrap();
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}
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}
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{
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let txin = &self.tx.input[input_index];
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let txin = &self.tx.input[input_index];
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txin
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txin
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@ -198,6 +201,7 @@ impl<'a> SigHashCache<'a> {
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script_code.consensus_encode(&mut enc).unwrap();
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script_code.consensus_encode(&mut enc).unwrap();
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value.consensus_encode(&mut enc).unwrap();
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value.consensus_encode(&mut enc).unwrap();
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txin.sequence.consensus_encode(&mut enc).unwrap();
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txin.sequence.consensus_encode(&mut enc).unwrap();
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}
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if sighash != SigHashType::Single && sighash != SigHashType::None {
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if sighash != SigHashType::Single && sighash != SigHashType::None {
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self.hash_outputs().consensus_encode(&mut enc).unwrap();
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self.hash_outputs().consensus_encode(&mut enc).unwrap();
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@ -215,6 +219,32 @@ impl<'a> SigHashCache<'a> {
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}
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}
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}
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}
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impl<R: DerefMut<Target=Transaction>> SigHashCache<R> {
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/// When the SigHashCache is initialized with a mutable reference to a transaction instead of a
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/// regular reference, this method is available to allow modification to the witnesses.
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///
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/// This allows in-line signing such as
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/// ```
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/// use bitcoin::blockdata::transaction::{Transaction, SigHashType};
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/// use bitcoin::util::bip143::SigHashCache;
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/// use bitcoin::Script;
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///
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/// let mut tx_to_sign = Transaction { version: 2, lock_time: 0, input: Vec::new(), output: Vec::new() };
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/// let input_count = tx_to_sign.input.len();
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///
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/// let mut sig_hasher = SigHashCache::new(&mut tx_to_sign);
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/// for inp in 0..input_count {
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/// let prevout_script = Script::new();
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/// let _sighash = sig_hasher.signature_hash(inp, &prevout_script, 42, SigHashType::All);
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/// // ... sign the sighash
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/// sig_hasher.access_witness(inp).push(Vec::new());
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/// }
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/// ```
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pub fn access_witness(&mut self, input_index: usize) -> &mut Vec<Vec<u8>> {
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&mut self.tx.input[input_index].witness
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}
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}
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#[cfg(test)]
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#[cfg(test)]
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#[allow(deprecated)]
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#[allow(deprecated)]
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mod tests {
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mod tests {
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