diff --git a/util/src/hex.rs b/util/src/hex.rs new file mode 100644 index 0000000..48ebd64 --- /dev/null +++ b/util/src/hex.rs @@ -0,0 +1,80 @@ +// Copyright 2020 The Grin Developers +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +//! Implements hex-encoding from bytes to string and decoding of strings +//! to bytes. Given that rustc-serialize is deprecated and serde doesn't +//! provide easy hex encoding, hex is a bit in limbo right now in Rust- +//! land. It's simple enough that we can just have our own. +use std::fmt::Write; +use std::num; + +/// Encode the provided bytes into a hex string +pub fn to_hex(bytes: Vec) -> String { + let mut s = String::new(); + for byte in bytes { + write!(&mut s, "{:02x}", byte).expect("Unable to write"); + } + s +} + +/// Decode a hex string into bytes. +pub fn from_hex(hex_str: String) -> Result, num::ParseIntError> { + if hex_str.len() % 2 == 1 { + // TODO: other way to instantiate a ParseIntError? + let err = ("QQQ").parse::(); + if let Err(e) = err { + return Err(e); + } + } + let hex_trim = if &hex_str[..2] == "0x" { + hex_str[2..].to_owned() + } else { + hex_str.clone() + }; + split_n(&hex_trim.trim()[..], 2) + .iter() + .map(|b| u8::from_str_radix(b, 16)) + .collect::, _>>() +} + +fn split_n(s: &str, n: usize) -> Vec<&str> { + (0..=(s.len() - n + 1) / 2) + .map(|i| &s[2 * i..2 * i + n]) + .collect() +} + +#[cfg(test)] +mod test { + use super::*; + + #[test] + fn test_to_hex() { + assert_eq!(to_hex(vec![0, 0, 0, 0]), "00000000"); + assert_eq!(to_hex(vec![10, 11, 12, 13]), "0a0b0c0d"); + assert_eq!(to_hex(vec![0, 0, 0, 255]), "000000ff"); + } + + #[test] + fn test_from_hex() { + assert_eq!(from_hex("00000000".to_string()).unwrap(), vec![0, 0, 0, 0]); + assert_eq!( + from_hex("0a0b0c0d".to_string()).unwrap(), + vec![10, 11, 12, 13] + ); + assert_eq!( + from_hex("000000ff".to_string()).unwrap(), + vec![0, 0, 0, 255] + ); + } +}