443 lines
14 KiB
Rust
443 lines
14 KiB
Rust
// Copyright 2013-2016 The rust-url developers.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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//! URLs use special chacters to indicate the parts of the request.
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//! For example, a `?` question mark marks the end of a path and the start of a query string.
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//! In order for that character to exist inside a path, it needs to be encoded differently.
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//!
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//! Percent encoding replaces reserved characters with the `%` escape character
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//! followed by a byte value as two hexadecimal digits.
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//! For example, an ASCII space is replaced with `%20`.
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//!
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//! When encoding, the set of characters that can (and should, for readability) be left alone
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//! depends on the context.
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//! The `?` question mark mentioned above is not a separator when used literally
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//! inside of a query string, and therefore does not need to be encoded.
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//! The [`AsciiSet`] parameter of [`percent_encode`] and [`utf8_percent_encode`]
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//! lets callers configure this.
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//!
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//! This crate delibarately does not provide many different sets.
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//! Users should consider in what context the encoded string will be used,
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//! real relevant specifications, and define their own set.
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//! This is done by using the `add` method of an existing set.
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//!
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//! # Examples
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//!
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//! ```
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//! use percent_encoding::{utf8_percent_encode, AsciiSet, CONTROLS};
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//!
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//! /// https://url.spec.whatwg.org/#fragment-percent-encode-set
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//! const FRAGMENT: &AsciiSet = &CONTROLS.add(b' ').add(b'"').add(b'<').add(b'>').add(b'`');
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//!
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//! assert_eq!(utf8_percent_encode("foo <bar>", FRAGMENT).to_string(), "foo%20%3Cbar%3E");
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//! ```
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use std::borrow::Cow;
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use std::fmt;
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use std::slice;
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use std::str;
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/// Represents a set of characters or bytes in the ASCII range.
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///
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/// This used in [`percent_encode`] and [`utf8_percent_encode`].
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/// This is simlar to [percent-encode sets](https://url.spec.whatwg.org/#percent-encoded-bytes).
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///
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/// Use the `add` method of an existing set to define a new set. For example:
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///
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/// ```
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/// use percent_encoding::{AsciiSet, CONTROLS};
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///
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/// /// https://url.spec.whatwg.org/#fragment-percent-encode-set
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/// const FRAGMENT: &AsciiSet = &CONTROLS.add(b' ').add(b'"').add(b'<').add(b'>').add(b'`');
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/// ```
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pub struct AsciiSet {
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mask: [Chunk; ASCII_RANGE_LEN / BITS_PER_CHUNK],
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}
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type Chunk = u32;
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const ASCII_RANGE_LEN: usize = 0x80;
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const BITS_PER_CHUNK: usize = 8 * std::mem::size_of::<Chunk>();
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impl AsciiSet {
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/// Called with UTF-8 bytes rather than code points.
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/// Not used for non-ASCII bytes.
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const fn contains(&self, byte: u8) -> bool {
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let chunk = self.mask[byte as usize / BITS_PER_CHUNK];
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let mask = 1 << (byte as usize % BITS_PER_CHUNK);
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(chunk & mask) != 0
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}
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fn should_percent_encode(&self, byte: u8) -> bool {
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!byte.is_ascii() || self.contains(byte)
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}
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pub const fn add(&self, byte: u8) -> Self {
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let mut mask = self.mask;
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mask[byte as usize / BITS_PER_CHUNK] |= 1 << (byte as usize % BITS_PER_CHUNK);
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AsciiSet { mask }
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}
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pub const fn remove(&self, byte: u8) -> Self {
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let mut mask = self.mask;
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mask[byte as usize / BITS_PER_CHUNK] &= !(1 << (byte as usize % BITS_PER_CHUNK));
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AsciiSet { mask }
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}
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}
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/// The set of 0x00 to 0x1F (C0 controls), and 0x7F (DEL).
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///
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/// Note that this includes the newline and tab characters, but not the space 0x20.
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///
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/// <https://url.spec.whatwg.org/#c0-control-percent-encode-set>
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pub const CONTROLS: &AsciiSet = &AsciiSet {
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mask: [
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!0_u32, // C0: 0x00 to 0x1F (32 bits set)
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0,
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0,
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1 << (0x7F_u32 % 32), // DEL: 0x7F (one bit set)
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],
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};
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macro_rules! static_assert {
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($( $bool: expr, )+) => {
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fn _static_assert() {
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$(
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let _ = std::mem::transmute::<[u8; $bool as usize], u8>;
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)+
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}
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}
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}
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static_assert! {
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CONTROLS.contains(0x00),
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CONTROLS.contains(0x1F),
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!CONTROLS.contains(0x20),
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!CONTROLS.contains(0x7E),
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CONTROLS.contains(0x7F),
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}
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/// Everything that is not an ASCII letter or digit.
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///
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/// This is probably more eager than necessary in any context.
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pub const NON_ALPHANUMERIC: &AsciiSet = &CONTROLS
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.add(b' ')
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.add(b'!')
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.add(b'"')
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.add(b'#')
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.add(b'$')
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.add(b'%')
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.add(b'&')
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.add(b'\'')
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.add(b'(')
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.add(b')')
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.add(b'*')
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.add(b'+')
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.add(b',')
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.add(b'-')
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.add(b'.')
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.add(b'/')
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.add(b':')
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.add(b';')
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.add(b'<')
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.add(b'=')
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.add(b'>')
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.add(b'?')
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.add(b'@')
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.add(b'[')
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.add(b'\\')
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.add(b']')
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.add(b'^')
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.add(b'_')
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.add(b'`')
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.add(b'{')
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.add(b'|')
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.add(b'}')
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.add(b'~');
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/// Return the percent-encoding of the given byte.
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///
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/// This is unconditional, unlike `percent_encode()` which has an `AsciiSet` parameter.
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///
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/// # Examples
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///
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/// ```
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/// use percent_encoding::percent_encode_byte;
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///
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/// assert_eq!("foo bar".bytes().map(percent_encode_byte).collect::<String>(),
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/// "%66%6F%6F%20%62%61%72");
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/// ```
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pub fn percent_encode_byte(byte: u8) -> &'static str {
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let index = usize::from(byte) * 3;
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&"\
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%00%01%02%03%04%05%06%07%08%09%0A%0B%0C%0D%0E%0F\
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%10%11%12%13%14%15%16%17%18%19%1A%1B%1C%1D%1E%1F\
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%20%21%22%23%24%25%26%27%28%29%2A%2B%2C%2D%2E%2F\
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%30%31%32%33%34%35%36%37%38%39%3A%3B%3C%3D%3E%3F\
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%40%41%42%43%44%45%46%47%48%49%4A%4B%4C%4D%4E%4F\
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%50%51%52%53%54%55%56%57%58%59%5A%5B%5C%5D%5E%5F\
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%60%61%62%63%64%65%66%67%68%69%6A%6B%6C%6D%6E%6F\
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%70%71%72%73%74%75%76%77%78%79%7A%7B%7C%7D%7E%7F\
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%80%81%82%83%84%85%86%87%88%89%8A%8B%8C%8D%8E%8F\
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%90%91%92%93%94%95%96%97%98%99%9A%9B%9C%9D%9E%9F\
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%A0%A1%A2%A3%A4%A5%A6%A7%A8%A9%AA%AB%AC%AD%AE%AF\
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%B0%B1%B2%B3%B4%B5%B6%B7%B8%B9%BA%BB%BC%BD%BE%BF\
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%C0%C1%C2%C3%C4%C5%C6%C7%C8%C9%CA%CB%CC%CD%CE%CF\
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%D0%D1%D2%D3%D4%D5%D6%D7%D8%D9%DA%DB%DC%DD%DE%DF\
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%E0%E1%E2%E3%E4%E5%E6%E7%E8%E9%EA%EB%EC%ED%EE%EF\
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%F0%F1%F2%F3%F4%F5%F6%F7%F8%F9%FA%FB%FC%FD%FE%FF\
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"[index..index + 3]
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}
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/// Percent-encode the given bytes with the given set.
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///
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/// Non-ASCII bytes and bytes in `ascii_set` are encoded.
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///
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/// The return type:
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///
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/// * Implements `Iterator<Item = &str>` and therefore has a `.collect::<String>()` method,
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/// * Implements `Display` and therefore has a `.to_string()` method,
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/// * Implements `Into<Cow<str>>` borrowing `input` when none of its bytes are encoded.
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///
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/// # Examples
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///
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/// ```
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/// use percent_encoding::{percent_encode, NON_ALPHANUMERIC};
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///
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/// assert_eq!(percent_encode(b"foo bar?", NON_ALPHANUMERIC).to_string(), "foo%20bar%3F");
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/// ```
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#[inline]
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pub fn percent_encode<'a>(input: &'a [u8], ascii_set: &'static AsciiSet) -> PercentEncode<'a> {
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PercentEncode {
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bytes: input,
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ascii_set,
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}
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}
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/// Percent-encode the UTF-8 encoding of the given string.
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///
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/// See [`percent_encode`] regarding the return type.
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///
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/// # Examples
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///
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/// ```
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/// use percent_encoding::{utf8_percent_encode, NON_ALPHANUMERIC};
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///
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/// assert_eq!(utf8_percent_encode("foo bar?", NON_ALPHANUMERIC).to_string(), "foo%20bar%3F");
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/// ```
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#[inline]
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pub fn utf8_percent_encode<'a>(input: &'a str, ascii_set: &'static AsciiSet) -> PercentEncode<'a> {
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percent_encode(input.as_bytes(), ascii_set)
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}
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/// The return type of [`percent_encode`] and [`utf8_percent_encode`].
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#[derive(Clone)]
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pub struct PercentEncode<'a> {
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bytes: &'a [u8],
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ascii_set: &'static AsciiSet,
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}
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impl<'a> Iterator for PercentEncode<'a> {
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type Item = &'a str;
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fn next(&mut self) -> Option<&'a str> {
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if let Some((&first_byte, remaining)) = self.bytes.split_first() {
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if self.ascii_set.should_percent_encode(first_byte) {
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self.bytes = remaining;
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Some(percent_encode_byte(first_byte))
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} else {
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for (i, &byte) in remaining.iter().enumerate() {
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if self.ascii_set.should_percent_encode(byte) {
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// 1 for first_byte + i for previous iterations of this loop
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let (unchanged_slice, remaining) = self.bytes.split_at(1 + i);
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self.bytes = remaining;
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return Some(unsafe { str::from_utf8_unchecked(unchanged_slice) });
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}
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}
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let unchanged_slice = self.bytes;
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self.bytes = &[][..];
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Some(unsafe { str::from_utf8_unchecked(unchanged_slice) })
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}
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} else {
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None
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}
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}
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fn size_hint(&self) -> (usize, Option<usize>) {
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if self.bytes.is_empty() {
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(0, Some(0))
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} else {
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(1, Some(self.bytes.len()))
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}
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}
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}
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impl<'a> fmt::Display for PercentEncode<'a> {
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fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
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for c in (*self).clone() {
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formatter.write_str(c)?
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}
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Ok(())
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}
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}
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impl<'a> From<PercentEncode<'a>> for Cow<'a, str> {
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fn from(mut iter: PercentEncode<'a>) -> Self {
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match iter.next() {
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None => "".into(),
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Some(first) => match iter.next() {
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None => first.into(),
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Some(second) => {
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let mut string = first.to_owned();
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string.push_str(second);
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string.extend(iter);
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string.into()
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}
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},
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}
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}
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}
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/// Percent-decode the given string.
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///
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/// <https://url.spec.whatwg.org/#string-percent-decode>
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///
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/// See [`percent_decode`] regarding the return type.
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#[inline]
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pub fn percent_decode_str(input: &str) -> PercentDecode {
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percent_decode(input.as_bytes())
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}
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/// Percent-decode the given bytes.
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///
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/// <https://url.spec.whatwg.org/#percent-decode>
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///
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/// Any sequence of `%` followed by two hexadecimal digits is decoded.
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/// The return type:
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///
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/// * Implements `Into<Cow<u8>>` borrowing `input` when it contains no percent-encoded sequence,
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/// * Implements `Iterator<Item = u8>` and therefore has a `.collect::<Vec<u8>>()` method,
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/// * Has `decode_utf8()` and `decode_utf8_lossy()` methods.
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///
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/// # Examples
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///
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/// ```
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/// use percent_encoding::percent_decode;
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///
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/// assert_eq!(percent_decode(b"foo%20bar%3f").decode_utf8().unwrap(), "foo bar?");
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/// ```
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#[inline]
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pub fn percent_decode(input: &[u8]) -> PercentDecode {
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PercentDecode {
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bytes: input.iter(),
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}
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}
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/// The return type of [`percent_decode`].
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#[derive(Clone, Debug)]
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pub struct PercentDecode<'a> {
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bytes: slice::Iter<'a, u8>,
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}
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fn after_percent_sign(iter: &mut slice::Iter<u8>) -> Option<u8> {
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let mut cloned_iter = iter.clone();
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let h = char::from(*cloned_iter.next()?).to_digit(16)?;
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let l = char::from(*cloned_iter.next()?).to_digit(16)?;
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*iter = cloned_iter;
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Some(h as u8 * 0x10 + l as u8)
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}
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impl<'a> Iterator for PercentDecode<'a> {
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type Item = u8;
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fn next(&mut self) -> Option<u8> {
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self.bytes.next().map(|&byte| {
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if byte == b'%' {
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after_percent_sign(&mut self.bytes).unwrap_or(byte)
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} else {
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byte
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}
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})
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}
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fn size_hint(&self) -> (usize, Option<usize>) {
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let bytes = self.bytes.len();
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(bytes / 3, Some(bytes))
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}
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}
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impl<'a> From<PercentDecode<'a>> for Cow<'a, [u8]> {
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fn from(iter: PercentDecode<'a>) -> Self {
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match iter.if_any() {
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Some(vec) => Cow::Owned(vec),
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None => Cow::Borrowed(iter.bytes.as_slice()),
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}
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}
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}
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impl<'a> PercentDecode<'a> {
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/// If the percent-decoding is different from the input, return it as a new bytes vector.
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fn if_any(&self) -> Option<Vec<u8>> {
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let mut bytes_iter = self.bytes.clone();
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while bytes_iter.any(|&b| b == b'%') {
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if let Some(decoded_byte) = after_percent_sign(&mut bytes_iter) {
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let initial_bytes = self.bytes.as_slice();
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let unchanged_bytes_len = initial_bytes.len() - bytes_iter.len() - 3;
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let mut decoded = initial_bytes[..unchanged_bytes_len].to_owned();
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decoded.push(decoded_byte);
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decoded.extend(PercentDecode { bytes: bytes_iter });
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return Some(decoded);
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}
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}
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// Nothing to decode
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None
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}
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/// Decode the result of percent-decoding as UTF-8.
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///
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/// This is return `Err` when the percent-decoded bytes are not well-formed in UTF-8.
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pub fn decode_utf8(self) -> Result<Cow<'a, str>, str::Utf8Error> {
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match self.clone().into() {
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Cow::Borrowed(bytes) => match str::from_utf8(bytes) {
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Ok(s) => Ok(s.into()),
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Err(e) => Err(e),
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},
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Cow::Owned(bytes) => match String::from_utf8(bytes) {
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Ok(s) => Ok(s.into()),
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Err(e) => Err(e.utf8_error()),
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},
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}
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}
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/// Decode the result of percent-decoding as UTF-8, lossily.
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///
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/// Invalid UTF-8 percent-encoded byte sequences will be replaced <20> U+FFFD,
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/// the replacement character.
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pub fn decode_utf8_lossy(self) -> Cow<'a, str> {
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decode_utf8_lossy(self.clone().into())
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}
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}
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fn decode_utf8_lossy(input: Cow<[u8]>) -> Cow<str> {
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match input {
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Cow::Borrowed(bytes) => String::from_utf8_lossy(bytes),
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Cow::Owned(bytes) => {
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let raw_utf8: *const [u8];
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match String::from_utf8_lossy(&bytes) {
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Cow::Borrowed(utf8) => raw_utf8 = utf8.as_bytes(),
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Cow::Owned(s) => return s.into(),
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}
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// from_utf8_lossy returned a borrow of `bytes` unchanged.
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debug_assert!(raw_utf8 == &*bytes as *const [u8]);
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// Reuse the existing `Vec` allocation.
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unsafe { String::from_utf8_unchecked(bytes) }.into()
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}
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}
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}
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