deaddrop-core 2.6.0

use crate::Result;
use crate::error::DdError;

pub fn hex_encode(bytes: &[u8]) -> String {
    const HEX: &[u8] = b"0123456789abcdef";
    let mut out = String::with_capacity(bytes.len() * 2);
    for b in bytes {
        out.push(HEX[(b >> 4) as usize] as char);
        out.push(HEX[(b & 0x0f) as usize] as char);
    }
    out
}

pub fn hex_decode(s: &str) -> Result<Vec<u8>> {
    if !s.len().is_multiple_of(2) {
        return Err(DdError::protocol(
            crate::error::ErrorCode::Ddp1005BadIdentifier,
            "odd hex length",
        ));
    }
    let mut out = Vec::with_capacity(s.len() / 2);
    let bytes = s.as_bytes();
    for i in (0..bytes.len()).step_by(2) {
        let hi = hex_val(bytes[i])?;
        let lo = hex_val(bytes[i + 1])?;
        out.push((hi << 4) | lo);
    }
    Ok(out)
}

fn hex_val(c: u8) -> Result<u8> {
    match c {
        b'0'..=b'9' => Ok(c - b'0'),
        b'a'..=b'f' => Ok(c - b'a' + 10),
        b'A'..=b'F' => Ok(c - b'A' + 10),
        _ => Err(DdError::protocol(
            crate::error::ErrorCode::Ddp1005BadIdentifier,
            "invalid hex",
        )),
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn hex_roundtrip() {
        let b = [0x7f, 0x4a, 0x91];
        assert_eq!(hex_decode(&hex_encode(&b)).unwrap(), b);
    }
}