aws_lc_rs/
hex.rs

1// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
2// SPDX-License-Identifier: Apache-2.0 OR ISC
3
4/// Converts bytes to a lower-case hex string
5#[allow(clippy::missing_panics_doc)]
6pub fn encode<T: AsRef<[u8]>>(bytes: T) -> String {
7    let bytes = bytes.as_ref();
8    let mut encoding = String::with_capacity(2 * bytes.len());
9    for byte in bytes {
10        let upper_val = byte >> 4u8;
11        let lower_val = byte & 0x0f;
12        // DON'T PANIC: it shouldn't be possible to panic because only bottom 4 bits can be set.
13        encoding.push(char::from_digit(u32::from(upper_val), 16).unwrap());
14        encoding.push(char::from_digit(u32::from(lower_val), 16).unwrap());
15    }
16    encoding
17}
18
19/// Converts bytes to an upper-case hex string
20pub fn encode_upper<T: AsRef<[u8]>>(bytes: T) -> String {
21    encode(bytes).to_ascii_uppercase()
22}
23
24/// Converts a hex string to a vector of bytes
25/// # Errors
26/// Returns an error if `hex_str` contains a non-hex digit.
27#[allow(clippy::missing_panics_doc)]
28pub fn decode(hex_str: &str) -> Result<Vec<u8>, String> {
29    let mut bytes = Vec::<u8>::with_capacity(hex_str.len() / 2 + 1);
30    let mut current_byte = b'\0';
31    let mut index: u32 = 0;
32    for ch in hex_str.chars() {
33        if !ch.is_ascii_hexdigit() {
34            return Err("Invalid hex string".to_string());
35        }
36        #[allow(clippy::cast_possible_truncation)]
37        // DON'T PANIC: it should not be possible to panic because we verify above that the character is a
38        // hex digit.
39        let value = ch.to_digit(16).unwrap() as u8;
40        if index % 2 == 0 {
41            current_byte = value << 4;
42        } else {
43            current_byte |= value;
44            bytes.push(current_byte);
45        }
46
47        if let Some(idx) = index.checked_add(1) {
48            index = idx;
49        } else {
50            break;
51        }
52    }
53    if index % 2 == 1 {
54        bytes.push(current_byte);
55    }
56    Ok(bytes)
57}
58
59/// Converts a hex string to a vector of bytes.
60/// It ignores any characters that are not valid hex digits.
61#[must_use]
62#[allow(clippy::missing_panics_doc)]
63pub fn decode_dirty(hex_str: &str) -> Vec<u8> {
64    let clean: String = hex_str.chars().filter(char::is_ascii_hexdigit).collect();
65    // DON'T PANIC: it should not be possible to panic because we filter out all non-hex digits.
66    decode(clean.as_str()).unwrap()
67}
aws_lc_rs/hex.rs

aws_lc_rs/
hex.rs
