tendermint-p2p 0.28.0

//! Secret Connection nonces

use std::convert::TryInto;

/// Size of a `ChaCha20` (IETF) nonce
pub const SIZE: usize = 12;

/// `SecretConnection` nonces (i.e. `ChaCha20` nonces)
pub struct Nonce(pub [u8; SIZE]);

impl Default for Nonce {
    fn default() -> Self {
        Self([0_u8; SIZE])
    }
}

impl Nonce {
    /// Increment the nonce's counter by 1
    pub fn increment(&mut self) {
        let counter: u64 = u64::from_le_bytes(self.0[4..].try_into().expect("framing failed"));
        self.0[4..].copy_from_slice(
            &counter
                .checked_add(1)
                .expect("overflow in counter addition")
                .to_le_bytes(),
        );
    }

    /// Serialize nonce as bytes (little endian)
    #[inline]
    #[must_use]
    pub fn to_bytes(&self) -> &[u8] {
        &self.0[..]
    }
}