1// Copyright 2013-2016 The rust-url developers.
2//
3// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
4// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
5// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
6// option. This file may not be copied, modified, or distributed
7// except according to those terms.
8
9//! URLs use special characters to indicate the parts of the request.
10//! For example, a `?` question mark marks the end of a path and the start of a query string.
11//! In order for that character to exist inside a path, it needs to be encoded differently.
12//!
13//! Percent encoding replaces reserved characters with the `%` escape character
14//! followed by a byte value as two hexadecimal digits.
15//! For example, an ASCII space is replaced with `%20`.
16//!
17//! When encoding, the set of characters that can (and should, for readability) be left alone
18//! depends on the context.
19//! The `?` question mark mentioned above is not a separator when used literally
20//! inside of a query string, and therefore does not need to be encoded.
21//! The [`AsciiSet`] parameter of [`percent_encode`] and [`utf8_percent_encode`]
22//! lets callers configure this.
23//!
24//! This crate deliberately does not provide many different sets.
25//! Users should consider in what context the encoded string will be used,
26//! read relevant specifications, and define their own set.
27//! This is done by using the `add` method of an existing set.
28//!
29//! # Examples
30//!
31//! ```
32//! use percent_encoding::{utf8_percent_encode, AsciiSet, CONTROLS};
33//!
34//! /// https://url.spec.whatwg.org/#fragment-percent-encode-set
35//! const FRAGMENT: &AsciiSet = &CONTROLS.add(b' ').add(b'"').add(b'<').add(b'>').add(b'`');
36//!
37//! assert_eq!(utf8_percent_encode("foo <bar>", FRAGMENT).to_string(), "foo%20%3Cbar%3E");
38//! ```
39#![no_std]
40
41// For forwards compatibility
42#[cfg(feature = "std")]
43extern crate std as _;
44
45#[cfg(feature = "alloc")]
46extern crate alloc;
47
48#[cfg(feature = "alloc")]
49use alloc::{
50 borrow::{Cow, ToOwned},
51 string::String,
52 vec::Vec,
53};
54use core::{fmt, mem, slice, str};
55
56/// Represents a set of characters or bytes in the ASCII range.
57///
58/// This is used in [`percent_encode`] and [`utf8_percent_encode`].
59/// This is similar to [percent-encode sets](https://url.spec.whatwg.org/#percent-encoded-bytes).
60///
61/// Use the `add` method of an existing set to define a new set. For example:
62///
63/// ```
64/// use percent_encoding::{AsciiSet, CONTROLS};
65///
66/// /// https://url.spec.whatwg.org/#fragment-percent-encode-set
67/// const FRAGMENT: &AsciiSet = &CONTROLS.add(b' ').add(b'"').add(b'<').add(b'>').add(b'`');
68/// ```
69pub struct AsciiSet {
70 mask: [Chunk; ASCII_RANGE_LEN / BITS_PER_CHUNK],
71}
72
73type Chunk = u32;
74
75const ASCII_RANGE_LEN: usize = 0x80;
76
77const BITS_PER_CHUNK: usize = 8 * mem::size_of::<Chunk>();
78
79impl AsciiSet {
80 /// Called with UTF-8 bytes rather than code points.
81 /// Not used for non-ASCII bytes.
82 const fn contains(&self, byte: u8) -> bool {
83 let chunk = self.mask[byte as usize / BITS_PER_CHUNK];
84 let mask = 1 << (byte as usize % BITS_PER_CHUNK);
85 (chunk & mask) != 0
86 }
87
88 fn should_percent_encode(&self, byte: u8) -> bool {
89 !byte.is_ascii() || self.contains(byte)
90 }
91
92 pub const fn add(&self, byte: u8) -> Self {
93 let mut mask = self.mask;
94 mask[byte as usize / BITS_PER_CHUNK] |= 1 << (byte as usize % BITS_PER_CHUNK);
95 AsciiSet { mask }
96 }
97
98 pub const fn remove(&self, byte: u8) -> Self {
99 let mut mask = self.mask;
100 mask[byte as usize / BITS_PER_CHUNK] &= !(1 << (byte as usize % BITS_PER_CHUNK));
101 AsciiSet { mask }
102 }
103}
104
105/// The set of 0x00 to 0x1F (C0 controls), and 0x7F (DEL).
106///
107/// Note that this includes the newline and tab characters, but not the space 0x20.
108///
109/// <https://url.spec.whatwg.org/#c0-control-percent-encode-set>
110pub const CONTROLS: &AsciiSet = &AsciiSet {
111 mask: [
112 !0_u32, // C0: 0x00 to 0x1F (32 bits set)
113 0,
114 0,
115 1 << (0x7F_u32 % 32), // DEL: 0x7F (one bit set)
116 ],
117};
118
119macro_rules! static_assert {
120 ($( $bool: expr, )+) => {
121 fn _static_assert() {
122 $(
123 let _ = mem::transmute::<[u8; $bool as usize], u8>;
124 )+
125 }
126 }
127}
128
129static_assert! {
130 CONTROLS.contains(0x00),
131 CONTROLS.contains(0x1F),
132 !CONTROLS.contains(0x20),
133 !CONTROLS.contains(0x7E),
134 CONTROLS.contains(0x7F),
135}
136
137/// Everything that is not an ASCII letter or digit.
138///
139/// This is probably more eager than necessary in any context.
140pub const NON_ALPHANUMERIC: &AsciiSet = &CONTROLS
141 .add(b' ')
142 .add(b'!')
143 .add(b'"')
144 .add(b'#')
145 .add(b'$')
146 .add(b'%')
147 .add(b'&')
148 .add(b'\'')
149 .add(b'(')
150 .add(b')')
151 .add(b'*')
152 .add(b'+')
153 .add(b',')
154 .add(b'-')
155 .add(b'.')
156 .add(b'/')
157 .add(b':')
158 .add(b';')
159 .add(b'<')
160 .add(b'=')
161 .add(b'>')
162 .add(b'?')
163 .add(b'@')
164 .add(b'[')
165 .add(b'\\')
166 .add(b']')
167 .add(b'^')
168 .add(b'_')
169 .add(b'`')
170 .add(b'{')
171 .add(b'|')
172 .add(b'}')
173 .add(byte:b'~');
174
175/// Return the percent-encoding of the given byte.
176///
177/// This is unconditional, unlike `percent_encode()` which has an `AsciiSet` parameter.
178///
179/// # Examples
180///
181/// ```
182/// use percent_encoding::percent_encode_byte;
183///
184/// assert_eq!("foo bar".bytes().map(percent_encode_byte).collect::<String>(),
185/// "%66%6F%6F%20%62%61%72");
186/// ```
187#[inline]
188pub fn percent_encode_byte(byte: u8) -> &'static str {
189 static ENC_TABLE: &[u8; 768] = b"\
190 %00%01%02%03%04%05%06%07%08%09%0A%0B%0C%0D%0E%0F\
191 %10%11%12%13%14%15%16%17%18%19%1A%1B%1C%1D%1E%1F\
192 %20%21%22%23%24%25%26%27%28%29%2A%2B%2C%2D%2E%2F\
193 %30%31%32%33%34%35%36%37%38%39%3A%3B%3C%3D%3E%3F\
194 %40%41%42%43%44%45%46%47%48%49%4A%4B%4C%4D%4E%4F\
195 %50%51%52%53%54%55%56%57%58%59%5A%5B%5C%5D%5E%5F\
196 %60%61%62%63%64%65%66%67%68%69%6A%6B%6C%6D%6E%6F\
197 %70%71%72%73%74%75%76%77%78%79%7A%7B%7C%7D%7E%7F\
198 %80%81%82%83%84%85%86%87%88%89%8A%8B%8C%8D%8E%8F\
199 %90%91%92%93%94%95%96%97%98%99%9A%9B%9C%9D%9E%9F\
200 %A0%A1%A2%A3%A4%A5%A6%A7%A8%A9%AA%AB%AC%AD%AE%AF\
201 %B0%B1%B2%B3%B4%B5%B6%B7%B8%B9%BA%BB%BC%BD%BE%BF\
202 %C0%C1%C2%C3%C4%C5%C6%C7%C8%C9%CA%CB%CC%CD%CE%CF\
203 %D0%D1%D2%D3%D4%D5%D6%D7%D8%D9%DA%DB%DC%DD%DE%DF\
204 %E0%E1%E2%E3%E4%E5%E6%E7%E8%E9%EA%EB%EC%ED%EE%EF\
205 %F0%F1%F2%F3%F4%F5%F6%F7%F8%F9%FA%FB%FC%FD%FE%FF\
206 ";
207
208 let index = usize::from(byte) * 3;
209 // SAFETY: ENC_TABLE is ascii-only, so any subset if it should be
210 // ascii-only too, which is valid utf8.
211 unsafe { str::from_utf8_unchecked(&ENC_TABLE[index..index + 3]) }
212}
213
214/// Percent-encode the given bytes with the given set.
215///
216/// Non-ASCII bytes and bytes in `ascii_set` are encoded.
217///
218/// The return type:
219///
220/// * Implements `Iterator<Item = &str>` and therefore has a `.collect::<String>()` method,
221/// * Implements `Display` and therefore has a `.to_string()` method,
222/// * Implements `Into<Cow<str>>` borrowing `input` when none of its bytes are encoded.
223///
224/// # Examples
225///
226/// ```
227/// use percent_encoding::{percent_encode, NON_ALPHANUMERIC};
228///
229/// assert_eq!(percent_encode(b"foo bar?", NON_ALPHANUMERIC).to_string(), "foo%20bar%3F");
230/// ```
231#[inline]
232pub fn percent_encode<'a>(input: &'a [u8], ascii_set: &'static AsciiSet) -> PercentEncode<'a> {
233 PercentEncode {
234 bytes: input,
235 ascii_set,
236 }
237}
238
239/// Percent-encode the UTF-8 encoding of the given string.
240///
241/// See [`percent_encode`] regarding the return type.
242///
243/// # Examples
244///
245/// ```
246/// use percent_encoding::{utf8_percent_encode, NON_ALPHANUMERIC};
247///
248/// assert_eq!(utf8_percent_encode("foo bar?", NON_ALPHANUMERIC).to_string(), "foo%20bar%3F");
249/// ```
250#[inline]
251pub fn utf8_percent_encode<'a>(input: &'a str, ascii_set: &'static AsciiSet) -> PercentEncode<'a> {
252 percent_encode(input.as_bytes(), ascii_set)
253}
254
255/// The return type of [`percent_encode`] and [`utf8_percent_encode`].
256#[derive(Clone)]
257pub struct PercentEncode<'a> {
258 bytes: &'a [u8],
259 ascii_set: &'static AsciiSet,
260}
261
262impl<'a> Iterator for PercentEncode<'a> {
263 type Item = &'a str;
264
265 fn next(&mut self) -> Option<&'a str> {
266 if let Some((&first_byte, remaining)) = self.bytes.split_first() {
267 if self.ascii_set.should_percent_encode(first_byte) {
268 self.bytes = remaining;
269 Some(percent_encode_byte(first_byte))
270 } else {
271 // The unsafe blocks here are appropriate because the bytes are
272 // confirmed as a subset of UTF-8 in should_percent_encode.
273 for (i, &byte) in remaining.iter().enumerate() {
274 if self.ascii_set.should_percent_encode(byte) {
275 // 1 for first_byte + i for previous iterations of this loop
276 let (unchanged_slice, remaining) = self.bytes.split_at(1 + i);
277 self.bytes = remaining;
278 return Some(unsafe { str::from_utf8_unchecked(unchanged_slice) });
279 }
280 }
281 let unchanged_slice = self.bytes;
282 self.bytes = &[][..];
283 Some(unsafe { str::from_utf8_unchecked(unchanged_slice) })
284 }
285 } else {
286 None
287 }
288 }
289
290 fn size_hint(&self) -> (usize, Option<usize>) {
291 if self.bytes.is_empty() {
292 (0, Some(0))
293 } else {
294 (1, Some(self.bytes.len()))
295 }
296 }
297}
298
299impl<'a> fmt::Display for PercentEncode<'a> {
300 fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
301 for c: &'a str in (*self).clone() {
302 formatter.write_str(data:c)?
303 }
304 Ok(())
305 }
306}
307
308#[cfg(feature = "alloc")]
309impl<'a> From<PercentEncode<'a>> for Cow<'a, str> {
310 fn from(mut iter: PercentEncode<'a>) -> Self {
311 match iter.next() {
312 None => "".into(),
313 Some(first: &'a str) => match iter.next() {
314 None => first.into(),
315 Some(second: &'a str) => {
316 let mut string: String = first.to_owned();
317 string.push_str(string:second);
318 string.extend(iter);
319 string.into()
320 }
321 },
322 }
323 }
324}
325
326/// Percent-decode the given string.
327///
328/// <https://url.spec.whatwg.org/#string-percent-decode>
329///
330/// See [`percent_decode`] regarding the return type.
331#[inline]
332pub fn percent_decode_str(input: &str) -> PercentDecode<'_> {
333 percent_decode(input.as_bytes())
334}
335
336/// Percent-decode the given bytes.
337///
338/// <https://url.spec.whatwg.org/#percent-decode>
339///
340/// Any sequence of `%` followed by two hexadecimal digits is decoded.
341/// The return type:
342///
343/// * Implements `Into<Cow<u8>>` borrowing `input` when it contains no percent-encoded sequence,
344/// * Implements `Iterator<Item = u8>` and therefore has a `.collect::<Vec<u8>>()` method,
345/// * Has `decode_utf8()` and `decode_utf8_lossy()` methods.
346///
347/// # Examples
348///
349/// ```
350/// use percent_encoding::percent_decode;
351///
352/// assert_eq!(percent_decode(b"foo%20bar%3f").decode_utf8().unwrap(), "foo bar?");
353/// ```
354#[inline]
355pub fn percent_decode(input: &[u8]) -> PercentDecode<'_> {
356 PercentDecode {
357 bytes: input.iter(),
358 }
359}
360
361/// The return type of [`percent_decode`].
362#[derive(Clone, Debug)]
363pub struct PercentDecode<'a> {
364 bytes: slice::Iter<'a, u8>,
365}
366
367fn after_percent_sign(iter: &mut slice::Iter<'_, u8>) -> Option<u8> {
368 let mut cloned_iter: Iter<'_, u8> = iter.clone();
369 let h: u32 = char::from(*cloned_iter.next()?).to_digit(radix:16)?;
370 let l: u32 = char::from(*cloned_iter.next()?).to_digit(radix:16)?;
371 *iter = cloned_iter;
372 Some(h as u8 * 0x10 + l as u8)
373}
374
375impl<'a> Iterator for PercentDecode<'a> {
376 type Item = u8;
377
378 fn next(&mut self) -> Option<u8> {
379 self.bytes.next().map(|&byte: u8| {
380 if byte == b'%' {
381 after_percent_sign(&mut self.bytes).unwrap_or(default:byte)
382 } else {
383 byte
384 }
385 })
386 }
387
388 fn size_hint(&self) -> (usize, Option<usize>) {
389 let bytes: usize = self.bytes.len();
390 ((bytes + 2) / 3, Some(bytes))
391 }
392}
393
394#[cfg(feature = "alloc")]
395impl<'a> From<PercentDecode<'a>> for Cow<'a, [u8]> {
396 fn from(iter: PercentDecode<'a>) -> Self {
397 match iter.if_any() {
398 Some(vec: Vec) => Cow::Owned(vec),
399 None => Cow::Borrowed(iter.bytes.as_slice()),
400 }
401 }
402}
403
404impl<'a> PercentDecode<'a> {
405 /// If the percent-decoding is different from the input, return it as a new bytes vector.
406 #[cfg(feature = "alloc")]
407 fn if_any(&self) -> Option<Vec<u8>> {
408 let mut bytes_iter = self.bytes.clone();
409 while bytes_iter.any(|&b| b == b'%') {
410 if let Some(decoded_byte) = after_percent_sign(&mut bytes_iter) {
411 let initial_bytes = self.bytes.as_slice();
412 let unchanged_bytes_len = initial_bytes.len() - bytes_iter.len() - 3;
413 let mut decoded = initial_bytes[..unchanged_bytes_len].to_owned();
414 decoded.push(decoded_byte);
415 decoded.extend(PercentDecode { bytes: bytes_iter });
416 return Some(decoded);
417 }
418 }
419 // Nothing to decode
420 None
421 }
422
423 /// Decode the result of percent-decoding as UTF-8.
424 ///
425 /// This is return `Err` when the percent-decoded bytes are not well-formed in UTF-8.
426 #[cfg(feature = "alloc")]
427 pub fn decode_utf8(self) -> Result<Cow<'a, str>, str::Utf8Error> {
428 match self.clone().into() {
429 Cow::Borrowed(bytes) => match str::from_utf8(bytes) {
430 Ok(s) => Ok(s.into()),
431 Err(e) => Err(e),
432 },
433 Cow::Owned(bytes) => match String::from_utf8(bytes) {
434 Ok(s) => Ok(s.into()),
435 Err(e) => Err(e.utf8_error()),
436 },
437 }
438 }
439
440 /// Decode the result of percent-decoding as UTF-8, lossily.
441 ///
442 /// Invalid UTF-8 percent-encoded byte sequences will be replaced � U+FFFD,
443 /// the replacement character.
444 #[cfg(feature = "alloc")]
445 pub fn decode_utf8_lossy(self) -> Cow<'a, str> {
446 decode_utf8_lossy(self.clone().into())
447 }
448}
449
450#[cfg(feature = "alloc")]
451fn decode_utf8_lossy(input: Cow<'_, [u8]>) -> Cow<'_, str> {
452 // Note: This function is duplicated in `form_urlencoded/src/query_encoding.rs`.
453 match input {
454 Cow::Borrowed(bytes) => String::from_utf8_lossy(bytes),
455 Cow::Owned(bytes) => {
456 match String::from_utf8_lossy(&bytes) {
457 Cow::Borrowed(utf8) => {
458 // If from_utf8_lossy returns a Cow::Borrowed, then we can
459 // be sure our original bytes were valid UTF-8. This is because
460 // if the bytes were invalid UTF-8 from_utf8_lossy would have
461 // to allocate a new owned string to back the Cow so it could
462 // replace invalid bytes with a placeholder.
463
464 // First we do a debug_assert to confirm our description above.
465 let raw_utf8: *const [u8] = utf8.as_bytes();
466 debug_assert!(raw_utf8 == &*bytes as *const [u8]);
467
468 // Given we know the original input bytes are valid UTF-8,
469 // and we have ownership of those bytes, we re-use them and
470 // return a Cow::Owned here.
471 Cow::Owned(unsafe { String::from_utf8_unchecked(bytes) })
472 }
473 Cow::Owned(s) => Cow::Owned(s),
474 }
475 }
476 }
477}
478