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tor-hspow: Simplify and optimize Challenge::new 

Challenges are now built using try_extend_from_slice instead of
iterators. There's no CPU benchmark in this crate yet, but I can confirm
that the resulting code is shorter. With this patch, the entirety of
Challenge:new() is automatically inlined at call sites.

Signed-off-by: Micah Elizabeth Scott <beth@torproject.org>
This commit is contained in:
Micah Elizabeth Scott 2023-07-19 17:38:06 -07:00
parent 7579febb46
commit bd48c23a40
1 changed files with 17 additions and 10 deletions
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27
crates/tor-hspow/src/v1/challenge.rs
View File

@ -5,7 +5,7 @@
//! solve and to verify puzzles.
use crate::v1::{Effort, Instance, Nonce, Seed, SolutionError, NONCE_LEN, SEED_LEN};
use arrayvec::ArrayVec;
use arrayvec::{ArrayVec, CapacityError};
use blake2::{digest::consts::U4, Blake2b, Digest};
/// Algorithm personalization string (P)
@ -50,15 +50,22 @@ impl Challenge {
/// a new byte array.
pub(super) fn new(instance: &Instance, effort: Effort, nonce: &Nonce) -> Self {
let mut result = ArrayVec::<u8, CHALLENGE_LEN>::new();
result.extend(P_STRING.iter().copied());
result.extend(instance.service().as_ref().iter().copied());
assert_eq!(result.len(), SEED_OFFSET);
result.extend(instance.seed().as_ref().iter().copied());
assert_eq!(result.len(), NONCE_OFFSET);
result.extend(nonce.as_ref().iter().copied());
assert_eq!(result.len(), EFFORT_OFFSET);
result.extend(effort.as_ref().to_be_bytes().into_iter());
Self(result.into_inner().expect("matching CHALLENGE_LEN"))
(|| -> Result<(), CapacityError> {
result.try_extend_from_slice(P_STRING)?;
result.try_extend_from_slice(instance.service().as_ref())?;
assert_eq!(result.len(), SEED_OFFSET);
result.try_extend_from_slice(instance.seed().as_ref())?;
assert_eq!(result.len(), NONCE_OFFSET);
result.try_extend_from_slice(nonce.as_ref())?;
assert_eq!(result.len(), EFFORT_OFFSET);
result.try_extend_from_slice(&effort.as_ref().to_be_bytes())
})()
.expect("CHALLENGE_LEN holds a full challenge string");
Self(
result
.into_inner()
.expect("challenge buffer is fully written"),
)
}
/// Clone the [`Seed`] portion of this challenge