56 lines
2.1 KiB
Rust
56 lines
2.1 KiB
Rust
//! Transaction ID computation. Contains code for generating the Transaction ID
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//! from the transaction.
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use std::{convert::TryInto, io};
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use super::{Hash, Transaction};
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use crate::serialization::{sha256d, ZcashSerialize};
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/// A Transaction ID builder. It computes the transaction ID by hashing
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/// different parts of the transaction, depending on the transaction version.
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/// For V5 transactions, it follows [ZIP-244] and [ZIP-225].
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///
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/// [ZIP-244]: https://zips.z.cash/zip-0244
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/// [ZIP-225]: https://zips.z.cash/zip-0225
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pub(super) struct TxIdBuilder<'a> {
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trans: &'a Transaction,
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}
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impl<'a> TxIdBuilder<'a> {
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/// Return a new TxIdBuilder for the given transaction.
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pub fn new(trans: &'a Transaction) -> Self {
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TxIdBuilder { trans }
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}
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/// Compute the Transaction ID for the previously specified transaction.
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pub(super) fn txid(self) -> Result<Hash, io::Error> {
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match self.trans {
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Transaction::V1 { .. }
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| Transaction::V2 { .. }
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| Transaction::V3 { .. }
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| Transaction::V4 { .. } => self.txid_v1_to_v4(),
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Transaction::V5 { .. } => self.txid_v5(),
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}
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}
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/// Compute the Transaction ID for transactions V1 to V4.
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/// In these cases it's simply the hash of the serialized transaction.
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#[allow(clippy::unwrap_in_result)]
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fn txid_v1_to_v4(self) -> Result<Hash, io::Error> {
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let mut hash_writer = sha256d::Writer::default();
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self.trans
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.zcash_serialize(&mut hash_writer)
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.expect("Transactions must serialize into the hash.");
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Ok(Hash(hash_writer.finish()))
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}
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/// Compute the Transaction ID for a V5 transaction in the given network upgrade.
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/// In this case it's the hash of a tree of hashes of specific parts of the
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/// transaction, as specified in ZIP-244 and ZIP-225.
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fn txid_v5(self) -> Result<Hash, io::Error> {
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// The v5 txid (from ZIP-244) is computed using librustzcash. Convert the zebra
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// transaction to a librustzcash transaction.
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let alt_tx: zcash_primitives::transaction::Transaction = self.trans.try_into()?;
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Ok(Hash(*alt_tx.txid().as_ref()))
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}
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}
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