Struct zaino_fetch::chain::block::BlockHeaderData

pub struct BlockHeaderData {
    pub version: i32,
    pub hash_prev_block: Vec<u8>,
    pub hash_merkle_root: Vec<u8>,
    pub hash_final_sapling_root: Vec<u8>,
    pub time: u32,
    pub n_bits_bytes: Vec<u8>,
    pub nonce: Vec<u8>,
    pub solution: Vec<u8>,
}

A block header, containing metadata about a block.

How are blocks chained together? They are chained together via the backwards reference (previous header hash) present in the block header. Each block points backwards to its parent, all the way back to the genesis block (the first block in the blockchain).

Fields

version: i32

The block’s version field. This is supposed to be 4:

The current and only defined block version number for Zcash is 4.

but this was not enforced by the consensus rules, and defective mining software created blocks with other versions, so instead it’s effectively a free field. The only constraint is that it must be at least 4 when interpreted as an i32.

Size [bytes]: 4

hash_prev_block: Vec<u8>

The hash of the previous block, used to create a chain of blocks back to the genesis block.

This ensures no previous block can be changed without also changing this block’s header.

Size [bytes]: 32

hash_merkle_root: Vec<u8>

The root of the Bitcoin-inherited transaction Merkle tree, binding the block header to the transactions in the block.

Note that because of a flaw in Bitcoin’s design, the merkle_root does not always precisely bind the contents of the block (CVE-2012-2459). It is sometimes possible for an attacker to create multiple distinct sets of transactions with the same Merkle root, although only one set will be valid.

Size [bytes]: 32

hash_final_sapling_root: Vec<u8>

[Pre-Sapling] A reserved field which should be ignored. [Sapling onward] The root LEBS2OSP_256(rt) of the Sapling note commitment tree corresponding to the final Sapling treestate of this block.

Size [bytes]: 32

time: u32

The block timestamp is a Unix epoch time (UTC) when the miner started hashing the header (according to the miner).

Size [bytes]: 4

n_bits_bytes: Vec<u8>

An encoded version of the target threshold this block’s header hash must be less than or equal to, in the same nBits format used by Bitcoin.

For a block at block height height, bits MUST be equal to ThresholdBits(height).

Bitcoin-nBits

Size [bytes]: 4

nonce: Vec<u8>

An arbitrary field that miners can change to modify the header hash in order to produce a hash less than or equal to the target threshold.

Size [bytes]: 32

solution: Vec<u8>

The Equihash solution.

Size [bytes]: CompactLength

Implementations

impl BlockHeaderData

pub fn to_binary(&self) -> Result<Vec<u8>, ParseError>

Serializes the block header into a byte vector.

pub fn get_hash(&self) -> Result<Vec<u8>, ParseError>

Extracts the block hash from the block header.

Trait Implementations

impl Debug for BlockHeaderData

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl ParseFromSlice for BlockHeaderData

fn parse_from_slice( data: &[u8], txid: Option<Vec<Vec<u8>>>, tx_version: Option<u32>, ) -> Result<(&[u8], Self), ParseError>

Reads data from a bytestring, consuming data read, and returns an instance of self along with the remaining data in the bytestring given.