130 lines
4.6 KiB
Rust
130 lines
4.6 KiB
Rust
//! Definitions of block datastructures.
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use chrono::{DateTime, Utc};
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use std::io;
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use crate::merkle_tree::MerkleTreeRootHash;
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use crate::note_commitment_tree::SaplingNoteTreeRootHash;
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use crate::serialization::{SerializationError, ZcashDeserialize, ZcashSerialize};
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use crate::sha256d_writer::Sha256dWriter;
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use crate::transaction::Transaction;
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/// A SHA-256d hash of a BlockHeader.
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///
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/// This is useful when one block header is pointing to its parent
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/// block header in the block chain. ⛓️
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///
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/// This is usually called a 'block hash', as it is frequently used
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/// to identify the entire block, since the hash preimage includes
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/// the merkle root of the transactions in this block. But
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/// _technically_, this is just a hash of the block _header_, not
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/// the direct bytes of the transactions as well as the header. So
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/// for now I want to call it a `BlockHeaderHash` because that's
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/// more explicit.
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#[derive(Clone, Debug, Eq, PartialEq)]
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pub struct BlockHeaderHash([u8; 32]);
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impl From<BlockHeader> for BlockHeaderHash {
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fn from(block_header: BlockHeader) -> Self {
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let mut hash_writer = Sha256dWriter::default();
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block_header
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.zcash_serialize(&mut hash_writer)
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.expect("Block headers must serialize.");
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Self(hash_writer.finish())
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}
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}
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/// Block header.
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///
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/// How are blocks chained together? They are chained together via the
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/// backwards reference (previous header hash) present in the block
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/// header. Each block points backwards to its parent, all the way
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/// back to the genesis block (the first block in the blockchain).
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#[derive(Clone, Debug, Eq, PartialEq)]
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pub struct BlockHeader {
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/// A SHA-256d hash in internal byte order of the previous block’s
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/// header. This ensures no previous block can be changed without
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/// also changing this block’s header.
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previous_block_hash: BlockHeaderHash,
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/// A SHA-256d hash in internal byte order. The merkle root is
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/// derived from the SHA256d hashes of all transactions included
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/// in this block as assembled in a binary tree, ensuring that
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/// none of those transactions can be modied without modifying the
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/// header.
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merkle_root_hash: MerkleTreeRootHash,
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/// [Sapling onward] The root LEBS2OSP256(rt) of the Sapling note
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/// commitment tree corresponding to the finnal Sapling treestate of
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/// this block.
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final_sapling_root_hash: SaplingNoteTreeRootHash,
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/// The block timestamp is a Unix epoch time (UTC) when the miner
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/// started hashing the header (according to the miner).
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time: DateTime<Utc>,
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/// An encoded version of the target threshold this block’s header
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/// hash must be less than or equal to, in the same nBits format
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/// used by Bitcoin.
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///
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/// For a block at block height height, bits MUST be equal to
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/// ThresholdBits(height).
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///
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/// [Bitcoin-nBits](https://bitcoin.org/en/developer-reference#target-nbits)
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// pzec has their own wrapper around u32 for this field:
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// https://github.com/ZcashFoundation/zebra/blob/master/zebra-primitives/src/compact.rs
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bits: u32,
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/// An arbitrary field that miners can change to modify the header
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/// hash in order to produce a hash less than or equal to the
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/// target threshold.
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nonce: [u8; 32],
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/// The Equihash solution.
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// The solution size when serialized should be in bytes ('always
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// 1344'). I first tried this as a [u8; 1344] but until const
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// generics land we'd have to implement all our common traits
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// manually, like in pzec.
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solution: Vec<u8>,
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}
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impl ZcashSerialize for BlockHeader {
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fn zcash_serialize<W: io::Write>(&self, writer: W) -> Result<(), SerializationError> {
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unimplemented!();
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}
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}
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impl ZcashDeserialize for BlockHeader {
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fn zcash_deserialize<R: io::Read>(reader: R) -> Result<Self, SerializationError> {
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unimplemented!();
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}
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}
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/// A block in your blockchain.
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///
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/// A block is a data structure with two fields:
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///
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/// Block header: a data structure containing the block's metadata
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/// Transactions: an array (vector in Rust) of transactions
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#[derive(Clone, Debug, Eq, PartialEq)]
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pub struct Block {
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/// First 80 bytes of the block as defined by the encoding used by
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/// "block" messages.
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pub header: BlockHeader,
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/// The block transactions.
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pub transactions: Vec<Transaction>,
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}
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impl ZcashSerialize for Block {
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fn zcash_serialize<W: io::Write>(&self, writer: W) -> Result<(), SerializationError> {
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unimplemented!();
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}
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}
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impl ZcashDeserialize for Block {
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fn zcash_deserialize<R: io::Read>(reader: R) -> Result<Self, SerializationError> {
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unimplemented!();
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}
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}
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