summaryrefslogtreecommitdiffstats
path: root/vendor/percent-encoding/src/lib.rs
blob: 46a5d747c95ac3da94a9acdb43aa15f755c03d7c (plain)
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
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
// Copyright 2013-2016 The rust-url developers.
//
// 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.

//! URLs use special characters to indicate the parts of the request.
//! For example, a `?` question mark marks the end of a path and the start of a query string.
//! In order for that character to exist inside a path, it needs to be encoded differently.
//!
//! Percent encoding replaces reserved characters with the `%` escape character
//! followed by a byte value as two hexadecimal digits.
//! For example, an ASCII space is replaced with `%20`.
//!
//! When encoding, the set of characters that can (and should, for readability) be left alone
//! depends on the context.
//! The `?` question mark mentioned above is not a separator when used literally
//! inside of a query string, and therefore does not need to be encoded.
//! The [`AsciiSet`] parameter of [`percent_encode`] and [`utf8_percent_encode`]
//! lets callers configure this.
//!
//! This crate deliberately does not provide many different sets.
//! Users should consider in what context the encoded string will be used,
//! read relevant specifications, and define their own set.
//! This is done by using the `add` method of an existing set.
//!
//! # Examples
//!
//! ```
//! use percent_encoding::{utf8_percent_encode, AsciiSet, CONTROLS};
//!
//! /// https://url.spec.whatwg.org/#fragment-percent-encode-set
//! const FRAGMENT: &AsciiSet = &CONTROLS.add(b' ').add(b'"').add(b'<').add(b'>').add(b'`');
//!
//! assert_eq!(utf8_percent_encode("foo <bar>", FRAGMENT).to_string(), "foo%20%3Cbar%3E");
//! ```

#![no_std]
#[cfg(feature = "alloc")]
extern crate alloc;

#[cfg(feature = "alloc")]
use alloc::{
    borrow::{Cow, ToOwned},
    string::String,
    vec::Vec,
};
use core::{fmt, mem, slice, str};

/// Represents a set of characters or bytes in the ASCII range.
///
/// This is used in [`percent_encode`] and [`utf8_percent_encode`].
/// This is similar to [percent-encode sets](https://url.spec.whatwg.org/#percent-encoded-bytes).
///
/// Use the `add` method of an existing set to define a new set. For example:
///
/// ```
/// use percent_encoding::{AsciiSet, CONTROLS};
///
/// /// https://url.spec.whatwg.org/#fragment-percent-encode-set
/// const FRAGMENT: &AsciiSet = &CONTROLS.add(b' ').add(b'"').add(b'<').add(b'>').add(b'`');
/// ```
pub struct AsciiSet {
    mask: [Chunk; ASCII_RANGE_LEN / BITS_PER_CHUNK],
}

type Chunk = u32;

const ASCII_RANGE_LEN: usize = 0x80;

const BITS_PER_CHUNK: usize = 8 * mem::size_of::<Chunk>();

impl AsciiSet {
    /// Called with UTF-8 bytes rather than code points.
    /// Not used for non-ASCII bytes.
    const fn contains(&self, byte: u8) -> bool {
        let chunk = self.mask[byte as usize / BITS_PER_CHUNK];
        let mask = 1 << (byte as usize % BITS_PER_CHUNK);
        (chunk & mask) != 0
    }

    fn should_percent_encode(&self, byte: u8) -> bool {
        !byte.is_ascii() || self.contains(byte)
    }

    pub const fn add(&self, byte: u8) -> Self {
        let mut mask = self.mask;
        mask[byte as usize / BITS_PER_CHUNK] |= 1 << (byte as usize % BITS_PER_CHUNK);
        AsciiSet { mask }
    }

    pub const fn remove(&self, byte: u8) -> Self {
        let mut mask = self.mask;
        mask[byte as usize / BITS_PER_CHUNK] &= !(1 << (byte as usize % BITS_PER_CHUNK));
        AsciiSet { mask }
    }
}

/// The set of 0x00 to 0x1F (C0 controls), and 0x7F (DEL).
///
/// Note that this includes the newline and tab characters, but not the space 0x20.
///
/// <https://url.spec.whatwg.org/#c0-control-percent-encode-set>
pub const CONTROLS: &AsciiSet = &AsciiSet {
    mask: [
        !0_u32, // C0: 0x00 to 0x1F (32 bits set)
        0,
        0,
        1 << (0x7F_u32 % 32), // DEL: 0x7F (one bit set)
    ],
};

macro_rules! static_assert {
    ($( $bool: expr, )+) => {
        fn _static_assert() {
            $(
                let _ = mem::transmute::<[u8; $bool as usize], u8>;
            )+
        }
    }
}

static_assert! {
    CONTROLS.contains(0x00),
    CONTROLS.contains(0x1F),
    !CONTROLS.contains(0x20),
    !CONTROLS.contains(0x7E),
    CONTROLS.contains(0x7F),
}

/// Everything that is not an ASCII letter or digit.
///
/// This is probably more eager than necessary in any context.
pub const NON_ALPHANUMERIC: &AsciiSet = &CONTROLS
    .add(b' ')
    .add(b'!')
    .add(b'"')
    .add(b'#')
    .add(b'$')
    .add(b'%')
    .add(b'&')
    .add(b'\'')
    .add(b'(')
    .add(b')')
    .add(b'*')
    .add(b'+')
    .add(b',')
    .add(b'-')
    .add(b'.')
    .add(b'/')
    .add(b':')
    .add(b';')
    .add(b'<')
    .add(b'=')
    .add(b'>')
    .add(b'?')
    .add(b'@')
    .add(b'[')
    .add(b'\\')
    .add(b']')
    .add(b'^')
    .add(b'_')
    .add(b'`')
    .add(b'{')
    .add(b'|')
    .add(b'}')
    .add(b'~');

/// Return the percent-encoding of the given byte.
///
/// This is unconditional, unlike `percent_encode()` which has an `AsciiSet` parameter.
///
/// # Examples
///
/// ```
/// use percent_encoding::percent_encode_byte;
///
/// assert_eq!("foo bar".bytes().map(percent_encode_byte).collect::<String>(),
///            "%66%6F%6F%20%62%61%72");
/// ```
pub fn percent_encode_byte(byte: u8) -> &'static str {
    let index = usize::from(byte) * 3;
    &"\
      %00%01%02%03%04%05%06%07%08%09%0A%0B%0C%0D%0E%0F\
      %10%11%12%13%14%15%16%17%18%19%1A%1B%1C%1D%1E%1F\
      %20%21%22%23%24%25%26%27%28%29%2A%2B%2C%2D%2E%2F\
      %30%31%32%33%34%35%36%37%38%39%3A%3B%3C%3D%3E%3F\
      %40%41%42%43%44%45%46%47%48%49%4A%4B%4C%4D%4E%4F\
      %50%51%52%53%54%55%56%57%58%59%5A%5B%5C%5D%5E%5F\
      %60%61%62%63%64%65%66%67%68%69%6A%6B%6C%6D%6E%6F\
      %70%71%72%73%74%75%76%77%78%79%7A%7B%7C%7D%7E%7F\
      %80%81%82%83%84%85%86%87%88%89%8A%8B%8C%8D%8E%8F\
      %90%91%92%93%94%95%96%97%98%99%9A%9B%9C%9D%9E%9F\
      %A0%A1%A2%A3%A4%A5%A6%A7%A8%A9%AA%AB%AC%AD%AE%AF\
      %B0%B1%B2%B3%B4%B5%B6%B7%B8%B9%BA%BB%BC%BD%BE%BF\
      %C0%C1%C2%C3%C4%C5%C6%C7%C8%C9%CA%CB%CC%CD%CE%CF\
      %D0%D1%D2%D3%D4%D5%D6%D7%D8%D9%DA%DB%DC%DD%DE%DF\
      %E0%E1%E2%E3%E4%E5%E6%E7%E8%E9%EA%EB%EC%ED%EE%EF\
      %F0%F1%F2%F3%F4%F5%F6%F7%F8%F9%FA%FB%FC%FD%FE%FF\
      "[index..index + 3]
}

/// Percent-encode the given bytes with the given set.
///
/// Non-ASCII bytes and bytes in `ascii_set` are encoded.
///
/// The return type:
///
/// * Implements `Iterator<Item = &str>` and therefore has a `.collect::<String>()` method,
/// * Implements `Display` and therefore has a `.to_string()` method,
/// * Implements `Into<Cow<str>>` borrowing `input` when none of its bytes are encoded.
///
/// # Examples
///
/// ```
/// use percent_encoding::{percent_encode, NON_ALPHANUMERIC};
///
/// assert_eq!(percent_encode(b"foo bar?", NON_ALPHANUMERIC).to_string(), "foo%20bar%3F");
/// ```
#[inline]
pub fn percent_encode<'a>(input: &'a [u8], ascii_set: &'static AsciiSet) -> PercentEncode<'a> {
    PercentEncode {
        bytes: input,
        ascii_set,
    }
}

/// Percent-encode the UTF-8 encoding of the given string.
///
/// See [`percent_encode`] regarding the return type.
///
/// # Examples
///
/// ```
/// use percent_encoding::{utf8_percent_encode, NON_ALPHANUMERIC};
///
/// assert_eq!(utf8_percent_encode("foo bar?", NON_ALPHANUMERIC).to_string(), "foo%20bar%3F");
/// ```
#[inline]
pub fn utf8_percent_encode<'a>(input: &'a str, ascii_set: &'static AsciiSet) -> PercentEncode<'a> {
    percent_encode(input.as_bytes(), ascii_set)
}

/// The return type of [`percent_encode`] and [`utf8_percent_encode`].
#[derive(Clone)]
pub struct PercentEncode<'a> {
    bytes: &'a [u8],
    ascii_set: &'static AsciiSet,
}

impl<'a> Iterator for PercentEncode<'a> {
    type Item = &'a str;

    fn next(&mut self) -> Option<&'a str> {
        if let Some((&first_byte, remaining)) = self.bytes.split_first() {
            if self.ascii_set.should_percent_encode(first_byte) {
                self.bytes = remaining;
                Some(percent_encode_byte(first_byte))
            } else {
                // The unsafe blocks here are appropriate because the bytes are
                // confirmed as a subset of UTF-8 in should_percent_encode.
                for (i, &byte) in remaining.iter().enumerate() {
                    if self.ascii_set.should_percent_encode(byte) {
                        // 1 for first_byte + i for previous iterations of this loop
                        let (unchanged_slice, remaining) = self.bytes.split_at(1 + i);
                        self.bytes = remaining;
                        return Some(unsafe { str::from_utf8_unchecked(unchanged_slice) });
                    }
                }
                let unchanged_slice = self.bytes;
                self.bytes = &[][..];
                Some(unsafe { str::from_utf8_unchecked(unchanged_slice) })
            }
        } else {
            None
        }
    }

    fn size_hint(&self) -> (usize, Option<usize>) {
        if self.bytes.is_empty() {
            (0, Some(0))
        } else {
            (1, Some(self.bytes.len()))
        }
    }
}

impl<'a> fmt::Display for PercentEncode<'a> {
    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
        for c in (*self).clone() {
            formatter.write_str(c)?
        }
        Ok(())
    }
}

#[cfg(feature = "alloc")]
impl<'a> From<PercentEncode<'a>> for Cow<'a, str> {
    fn from(mut iter: PercentEncode<'a>) -> Self {
        match iter.next() {
            None => "".into(),
            Some(first) => match iter.next() {
                None => first.into(),
                Some(second) => {
                    let mut string = first.to_owned();
                    string.push_str(second);
                    string.extend(iter);
                    string.into()
                }
            },
        }
    }
}

/// Percent-decode the given string.
///
/// <https://url.spec.whatwg.org/#string-percent-decode>
///
/// See [`percent_decode`] regarding the return type.
#[inline]
pub fn percent_decode_str(input: &str) -> PercentDecode<'_> {
    percent_decode(input.as_bytes())
}

/// Percent-decode the given bytes.
///
/// <https://url.spec.whatwg.org/#percent-decode>
///
/// Any sequence of `%` followed by two hexadecimal digits is decoded.
/// The return type:
///
/// * Implements `Into<Cow<u8>>` borrowing `input` when it contains no percent-encoded sequence,
/// * Implements `Iterator<Item = u8>` and therefore has a `.collect::<Vec<u8>>()` method,
/// * Has `decode_utf8()` and `decode_utf8_lossy()` methods.
///
/// # Examples
///
/// ```
/// use percent_encoding::percent_decode;
///
/// assert_eq!(percent_decode(b"foo%20bar%3f").decode_utf8().unwrap(), "foo bar?");
/// ```
#[inline]
pub fn percent_decode(input: &[u8]) -> PercentDecode<'_> {
    PercentDecode {
        bytes: input.iter(),
    }
}

/// The return type of [`percent_decode`].
#[derive(Clone, Debug)]
pub struct PercentDecode<'a> {
    bytes: slice::Iter<'a, u8>,
}

fn after_percent_sign(iter: &mut slice::Iter<'_, u8>) -> Option<u8> {
    let mut cloned_iter = iter.clone();
    let h = char::from(*cloned_iter.next()?).to_digit(16)?;
    let l = char::from(*cloned_iter.next()?).to_digit(16)?;
    *iter = cloned_iter;
    Some(h as u8 * 0x10 + l as u8)
}

impl<'a> Iterator for PercentDecode<'a> {
    type Item = u8;

    fn next(&mut self) -> Option<u8> {
        self.bytes.next().map(|&byte| {
            if byte == b'%' {
                after_percent_sign(&mut self.bytes).unwrap_or(byte)
            } else {
                byte
            }
        })
    }

    fn size_hint(&self) -> (usize, Option<usize>) {
        let bytes = self.bytes.len();
        ((bytes + 2) / 3, Some(bytes))
    }
}

#[cfg(feature = "alloc")]
impl<'a> From<PercentDecode<'a>> for Cow<'a, [u8]> {
    fn from(iter: PercentDecode<'a>) -> Self {
        match iter.if_any() {
            Some(vec) => Cow::Owned(vec),
            None => Cow::Borrowed(iter.bytes.as_slice()),
        }
    }
}

impl<'a> PercentDecode<'a> {
    /// If the percent-decoding is different from the input, return it as a new bytes vector.
    #[cfg(feature = "alloc")]
    fn if_any(&self) -> Option<Vec<u8>> {
        let mut bytes_iter = self.bytes.clone();
        while bytes_iter.any(|&b| b == b'%') {
            if let Some(decoded_byte) = after_percent_sign(&mut bytes_iter) {
                let initial_bytes = self.bytes.as_slice();
                let unchanged_bytes_len = initial_bytes.len() - bytes_iter.len() - 3;
                let mut decoded = initial_bytes[..unchanged_bytes_len].to_owned();
                decoded.push(decoded_byte);
                decoded.extend(PercentDecode { bytes: bytes_iter });
                return Some(decoded);
            }
        }
        // Nothing to decode
        None
    }

    /// Decode the result of percent-decoding as UTF-8.
    ///
    /// This is return `Err` when the percent-decoded bytes are not well-formed in UTF-8.
    #[cfg(feature = "alloc")]
    pub fn decode_utf8(self) -> Result<Cow<'a, str>, str::Utf8Error> {
        match self.clone().into() {
            Cow::Borrowed(bytes) => match str::from_utf8(bytes) {
                Ok(s) => Ok(s.into()),
                Err(e) => Err(e),
            },
            Cow::Owned(bytes) => match String::from_utf8(bytes) {
                Ok(s) => Ok(s.into()),
                Err(e) => Err(e.utf8_error()),
            },
        }
    }

    /// Decode the result of percent-decoding as UTF-8, lossily.
    ///
    /// Invalid UTF-8 percent-encoded byte sequences will be replaced � U+FFFD,
    /// the replacement character.
    #[cfg(feature = "alloc")]
    pub fn decode_utf8_lossy(self) -> Cow<'a, str> {
        decode_utf8_lossy(self.clone().into())
    }
}

#[cfg(feature = "alloc")]
fn decode_utf8_lossy(input: Cow<'_, [u8]>) -> Cow<'_, str> {
    // Note: This function is duplicated in `form_urlencoded/src/query_encoding.rs`.
    match input {
        Cow::Borrowed(bytes) => String::from_utf8_lossy(bytes),
        Cow::Owned(bytes) => {
            match String::from_utf8_lossy(&bytes) {
                Cow::Borrowed(utf8) => {
                    // If from_utf8_lossy returns a Cow::Borrowed, then we can
                    // be sure our original bytes were valid UTF-8. This is because
                    // if the bytes were invalid UTF-8 from_utf8_lossy would have
                    // to allocate a new owned string to back the Cow so it could
                    // replace invalid bytes with a placeholder.

                    // First we do a debug_assert to confirm our description above.
                    let raw_utf8: *const [u8] = utf8.as_bytes();
                    debug_assert!(raw_utf8 == &*bytes as *const [u8]);

                    // Given we know the original input bytes are valid UTF-8,
                    // and we have ownership of those bytes, we re-use them and
                    // return a Cow::Owned here.
                    Cow::Owned(unsafe { String::from_utf8_unchecked(bytes) })
                }
                Cow::Owned(s) => Cow::Owned(s),
            }
        }
    }
}