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// Copyright 2013-2016 The rust-url developers.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// 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};
//!
//! 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]
// For forwards compatibility
#[cfg(feature = "std")]
extern crate std as _;
#[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`].
///
/// Use the `add` method of an existing set to define a new set. For example:
///
/// ```
/// use percent_encoding::{AsciiSet, CONTROLS};
///
/// 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.
///
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");
/// ```
#[inline]
pub fn percent_encode_byte(byte: u8) -> &'static str {
static ENC_TABLE: &[u8; 768] = b"\
%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\
";
let index = usize::from(byte) * 3;
// SAFETY: ENC_TABLE is ascii-only, so any subset if it should be
// ascii-only too, which is valid utf8.
unsafe { str::from_utf8_unchecked(&ENC_TABLE[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.
///
///
/// 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.
///
///
/// 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),
}
}
}
}