1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
// Copyright 2013-2014 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

//! Hex binary-to-text encoding

#![cfg_attr(not(feature = "std"), no_std)]
#![warn(missing_docs)]

use core::fmt;
use core::iter::{self, FromIterator};

pub use self::FromHexError::*;

/// A trait for converting a value to hexadecimal encoding
pub trait ToHex {
    /// Converts the value of `self` to a hex value, constructed from
    /// an iterator of characters.
    fn to_hex<T: FromIterator<char>>(&self) -> T;
}

static CHARS: &'static [u8] = b"0123456789abcdef";

impl ToHex for [u8] {
    /// Turn a slice of `u8` bytes into a hexadecimal string.
    ///
    /// # Example
    ///
    /// ```rust
    /// use rustc_hex::ToHex;
    ///
    /// fn main () {
    ///     let str: String = [52,32].to_hex();
    ///     println!("{}", str);
    /// }
    /// ```
    fn to_hex<T: FromIterator<char>>(&self) -> T {
        ToHexIter::new(self.iter()).collect()
    }
}

impl<'a, T: ?Sized + ToHex> ToHex for &'a T {
    fn to_hex<U: FromIterator<char>>(&self) -> U {
        (**self).to_hex()
    }
}

/// An iterator converting byte slice to a set of hex characters.
pub struct ToHexIter<T> {
    live: Option<char>,
    inner: T,
}

impl<T> ToHexIter<T> {
    /// Create new hex-converting iterator.
    ///
    /// # Example
    ///
    /// ```rust
    /// fn main () {
    ///     let bytes = vec![1, 2, 3, 4];
    ///     let iter = rustc_hex::ToHexIter::new(bytes.iter());
    ///     println!("{}", iter.collect::<String>());
    /// }
    /// ```
    pub fn new(inner: T) -> Self {
        Self {
            live: None,
            inner,
        }
    }
}

impl<'a, T: Iterator<Item = &'a u8>> Iterator for ToHexIter<T> {
    type Item = char;

    fn next(&mut self) -> Option<char> {
        if let Some(live) = self.live.take() {
            return Some(live);
        }

        self.inner.next().map(|&byte| {
            let current = CHARS[(byte >> 4) as usize] as char;
            self.live = Some(CHARS[(byte & 0xf) as usize] as char);
            current
        })
    }

    fn size_hint(&self) -> (usize, Option<usize>) {
        let (a, b) = self.inner.size_hint();
        (a.saturating_mul(2), b.map(|b| b.saturating_mul(2)))
    }
}

impl<'a, T: iter::ExactSizeIterator + Iterator<Item = &'a u8>> iter::ExactSizeIterator for ToHexIter<T> {
    fn len(&self) -> usize {
        let mut len = self.inner.len() * 2;
        if self.live.is_some() {
            len += 1;
        }
        len
    }
}

/// A from-hex conversion trait.
pub trait FromHex {
    /// Converts the value of `self`, interpreted as hexadecimal encoded data,
    /// into an owned value constructed from an iterator of bytes.
    fn from_hex<T: FromIterator<u8>>(&self) -> Result<T, FromHexError>;
}

/// Errors that can occur when decoding a hex encoded string
#[derive(Clone, Copy)]
pub enum FromHexError {
    /// The input contained a character not part of the hex format
    InvalidHexCharacter(char, usize),
    /// The input had an invalid length
    InvalidHexLength,
}

impl fmt::Debug for FromHexError {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match *self {
            InvalidHexCharacter(ch, idx) =>
                write!(f, "Invalid character '{}' at position {}", ch, idx),
            InvalidHexLength => write!(f, "Invalid input length"),
        }
    }
}

#[cfg(feature = "std")]
impl ::std::error::Error for FromHexError {
    fn description(&self) -> &str {
        match *self {
            InvalidHexCharacter(_, _) => "invalid character",
            InvalidHexLength => "invalid length",
        }
    }
}

#[cfg(feature = "std")]
impl fmt::Display for FromHexError {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        fmt::Debug::fmt(&self, f)
    }
}

#[cfg(not(feature = "std"))]
impl fmt::Display for FromHexError {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match *self {
            InvalidHexCharacter(ch, idx) => {
                f.write_str("invalid character: ")?;
                ch.fmt(f)?;
                f.write_str(" at index ")?;
                idx.fmt(f)
            }
            InvalidHexLength => f.write_str("invalid length"),
        }
    }
}

impl FromHex for str {
    /// Convert any hexadecimal encoded string (literal, `@`, `&`, or `~`)
    /// to the byte values it encodes.
    ///
    /// You can use the `String::from_utf8` function to turn a
    /// `Vec<u8>` into a string with characters corresponding to those values.
    ///
    /// # Example
    ///
    /// This converts a string literal to hexadecimal and back.
    ///
    /// ```rust
    /// extern crate rustc_hex;
    /// use rustc_hex::{FromHex, ToHex};
    ///
    /// fn main () {
    ///     let hello_str: String = "Hello, World".as_bytes().to_hex();
    ///     println!("{}", hello_str);
    ///     let bytes: Vec<u8> = hello_str.from_hex().unwrap();
    ///     println!("{:?}", bytes);
    ///     let result_str = String::from_utf8(bytes).unwrap();
    ///     println!("{}", result_str);
    /// }
    /// ```
    fn from_hex<T: FromIterator<u8>>(&self) -> Result<T, FromHexError> {
        FromHexIter::new(self).collect()
    }
}

impl<'a, T: ?Sized + FromHex> FromHex for &'a T {
    fn from_hex<U: FromIterator<u8>>(&self) -> Result<U, FromHexError> {
        (**self).from_hex()
    }
}

/// An iterator decoding hex-encoded characters into bytes.
pub struct FromHexIter<'a> {
    err: bool,
    inner: &'a str,
    iter: iter::Enumerate<core::str::Bytes<'a>>,
}

impl<'a> FromHexIter<'a> {
    /// Create new hex-decoding iterator.
    /// # Example
    ///
    /// ```rust
    /// fn main () {
    ///     let s = "ff0102";
    ///     let iter = rustc_hex::FromHexIter::new(s);
    ///     println!("{:?}", iter.collect::<Vec<_>>());
    /// }
    /// ```
    pub fn new(inner: &'a str) -> Self {
        let iter = inner.bytes().enumerate();
        Self {
            err: false,
            inner,
            iter,
        }
    }
}

impl<'a> Iterator for FromHexIter<'a> {
    type Item = Result<u8, FromHexError>;

    fn next(&mut self) -> Option<Result<u8, FromHexError>> {
        if self.err {
            return None;
        }

        let mut modulus = 0;
        let mut buf = 0;
        for (idx, byte) in &mut self.iter {
            buf <<= 4;

            match byte {
                b'A'..=b'F' => buf |= byte - b'A' + 10,
                b'a'..=b'f' => buf |= byte - b'a' + 10,
                b'0'..=b'9' => buf |= byte - b'0',
                b' '|b'\r'|b'\n'|b'\t' => {
                    buf >>= 4;
                    continue
                }
                _ => {
                    let ch = self.inner[idx..].chars().next().unwrap();
                    self.err = true;
                    return Some(Err(InvalidHexCharacter(ch, idx)));
                }
            }

            modulus += 1;
            if modulus == 2 {
                return Some(Ok(buf));
            }
        }

        if modulus != 0 {
            self.err = true;
            return Some(Err(InvalidHexLength));
        }

        None
    }

    fn size_hint(&self) -> (usize, Option<usize>) {
        let (a, b) = self.iter.size_hint();
        (a / 2, b.map(|b| b / 2))
    }
}

#[cfg(test)]
mod tests {
    use super::{FromHex, ToHex};
    #[cfg(not(feature = "std"))]
    extern crate alloc;
    #[cfg(not(feature = "std"))]
    use alloc::{string::String, vec::Vec, format};

    #[test]
    pub fn test_to_hex() {
        assert_eq!("foobar".as_bytes().to_hex::<String>(), "666f6f626172");
    }

    #[test]
    pub fn test_from_hex_okay() {
        assert_eq!("666f6f626172".from_hex::<Vec<_>>().unwrap(),
                   b"foobar");
        assert_eq!("666F6F626172".from_hex::<Vec<_>>().unwrap(),
                   b"foobar");
    }

    #[test]
    pub fn test_from_hex_odd_len() {
        assert!("666".from_hex::<Vec<_>>().is_err());
        assert!("66 6".from_hex::<Vec<_>>().is_err());
    }

    #[test]
    pub fn test_from_hex_invalid_char() {
        assert!("66y6".from_hex::<Vec<_>>().is_err());
    }

    #[test]
    pub fn test_from_hex_ignores_whitespace() {
        assert_eq!("666f 6f6\r\n26172 ".from_hex::<Vec<_>>().unwrap(),
                   b"foobar");
    }

    #[test]
    pub fn test_to_hex_all_bytes() {
        for i in 0..256 {
            assert_eq!([i as u8].to_hex::<String>(), format!("{:02x}", i));
        }
    }

    #[test]
    pub fn test_from_hex_all_bytes() {
        for i in 0..256 {
            let ii: &[u8] = &[i as u8];
            assert_eq!(format!("{:02x}", i).from_hex::<Vec<_>>().unwrap(),
                       ii);
            assert_eq!(format!("{:02X}", i).from_hex::<Vec<_>>().unwrap(),
                       ii);
        }
    }
}