solana_sdk/
shred_version.rs

1//! Calculation of [shred] versions.
2//!
3//! [shred]: https://solana.com/docs/terminology#shred
4
5#![cfg(feature = "full")]
6
7use solana_sdk::{
8    hard_forks::HardForks,
9    hash::{extend_and_hash, Hash},
10};
11
12pub fn version_from_hash(hash: &Hash) -> u16 {
13    let hash = hash.as_ref();
14    let mut accum = [0u8; 2];
15    hash.chunks(2).for_each(|seed| {
16        accum
17            .iter_mut()
18            .zip(seed)
19            .for_each(|(accum, seed)| *accum ^= *seed)
20    });
21    // convert accum into a u16
22    // Because accum[0] is a u8, 8bit left shift of the u16 can never overflow
23    #[allow(clippy::arithmetic_side_effects)]
24    let version = ((accum[0] as u16) << 8) | accum[1] as u16;
25
26    // ensure version is never zero, to avoid looking like an uninitialized version
27    version.saturating_add(1)
28}
29
30pub fn compute_shred_version(genesis_hash: &Hash, hard_forks: Option<&HardForks>) -> u16 {
31    use byteorder::{ByteOrder, LittleEndian};
32
33    let mut hash = *genesis_hash;
34    if let Some(hard_forks) = hard_forks {
35        for (slot, count) in hard_forks.iter() {
36            let mut buf = [0u8; 16];
37            LittleEndian::write_u64(&mut buf[..8], *slot);
38            LittleEndian::write_u64(&mut buf[8..], *count as u64);
39            hash = extend_and_hash(&hash, &buf);
40        }
41    }
42
43    version_from_hash(&hash)
44}
45
46#[cfg(test)]
47mod tests {
48    use super::*;
49
50    #[test]
51    fn test_compute_shred_version() {
52        assert_eq!(compute_shred_version(&Hash::default(), None), 1);
53        let mut hard_forks = HardForks::default();
54        assert_eq!(
55            compute_shred_version(&Hash::default(), Some(&hard_forks)),
56            1
57        );
58        hard_forks.register(1);
59        assert_eq!(
60            compute_shred_version(&Hash::default(), Some(&hard_forks)),
61            55551
62        );
63        hard_forks.register(1);
64        assert_eq!(
65            compute_shred_version(&Hash::default(), Some(&hard_forks)),
66            46353
67        );
68    }
69}
solana_sdk/shred_version.rs

solana_sdk/
shred_version.rs
