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
// Copyright 2013 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.
//! Punycode ([RFC 3492](http://tools.ietf.org/html/rfc3492)) implementation.
//!
//! Since Punycode fundamentally works on unicode code points,
//! `encode` and `decode` take and return slices and vectors of `char`.
//! `encode_str` and `decode_to_string` provide convenience wrappers
//! that convert from and to Rust’s UTF-8 based `str` and `String` types.
use alloc::{string::String, vec::Vec};
use core::char;
use core::u32;
// Bootstring parameters for Punycode
static BASE: u32 = 36;
static T_MIN: u32 = 1;
static T_MAX: u32 = 26;
static SKEW: u32 = 38;
static DAMP: u32 = 700;
static INITIAL_BIAS: u32 = 72;
static INITIAL_N: u32 = 0x80;
static DELIMITER: char = '-';
#[inline]
fn adapt(mut delta: u32, num_points: u32, first_time: bool) -> u32 {
delta /= if first_time { DAMP } else { 2 };
delta += delta / num_points;
let mut k = 0;
while delta > ((BASE - T_MIN) * T_MAX) / 2 {
delta /= BASE - T_MIN;
k += BASE;
}
k + (((BASE - T_MIN + 1) * delta) / (delta + SKEW))
}
/// Convert Punycode to an Unicode `String`.
///
/// This is a convenience wrapper around `decode`.
#[inline]
pub fn decode_to_string(input: &str) -> Option<String> {
decode(input).map(|chars| chars.into_iter().collect())
}
/// Convert Punycode to Unicode.
///
/// Return None on malformed input or overflow.
/// Overflow can only happen on inputs that take more than
/// 63 encoded bytes, the DNS limit on domain name labels.
pub fn decode(input: &str) -> Option<Vec<char>> {
Some(Decoder::default().decode(input).ok()?.collect())
}
#[derive(Default)]
pub(crate) struct Decoder {
insertions: Vec<(usize, char)>,
}
impl Decoder {
/// Split the input iterator and return a Vec with insertions of encoded characters
pub(crate) fn decode<'a>(&'a mut self, input: &'a str) -> Result<Decode<'a>, ()> {
self.insertions.clear();
// Handle "basic" (ASCII) code points.
// They are encoded as-is before the last delimiter, if any.
let (base, input) = match input.rfind(DELIMITER) {
None => ("", input),
Some(position) => (
&input[..position],
if position > 0 {
&input[position + 1..]
} else {
input
},
),
};
if !base.is_ascii() {
return Err(());
}
let base_len = base.len();
let mut length = base_len as u32;
let mut code_point = INITIAL_N;
let mut bias = INITIAL_BIAS;
let mut i = 0;
let mut iter = input.bytes();
loop {
let previous_i = i;
let mut weight = 1;
let mut k = BASE;
let mut byte = match iter.next() {
None => break,
Some(byte) => byte,
};
// Decode a generalized variable-length integer into delta,
// which gets added to i.
loop {
let digit = match byte {
byte @ b'0'..=b'9' => byte - b'0' + 26,
byte @ b'A'..=b'Z' => byte - b'A',
byte @ b'a'..=b'z' => byte - b'a',
_ => return Err(()),
} as u32;
if digit > (u32::MAX - i) / weight {
return Err(()); // Overflow
}
i += digit * weight;
let t = if k <= bias {
T_MIN
} else if k >= bias + T_MAX {
T_MAX
} else {
k - bias
};
if digit < t {
break;
}
if weight > u32::MAX / (BASE - t) {
return Err(()); // Overflow
}
weight *= BASE - t;
k += BASE;
byte = match iter.next() {
None => return Err(()), // End of input before the end of this delta
Some(byte) => byte,
};
}
bias = adapt(i - previous_i, length + 1, previous_i == 0);
if i / (length + 1) > u32::MAX - code_point {
return Err(()); // Overflow
}
// i was supposed to wrap around from length+1 to 0,
// incrementing code_point each time.
code_point += i / (length + 1);
i %= length + 1;
let c = match char::from_u32(code_point) {
Some(c) => c,
None => return Err(()),
};
// Move earlier insertions farther out in the string
for (idx, _) in &mut self.insertions {
if *idx >= i as usize {
*idx += 1;
}
}
self.insertions.push((i as usize, c));
length += 1;
i += 1;
}
self.insertions.sort_by_key(|(i, _)| *i);
Ok(Decode {
base: base.chars(),
insertions: &self.insertions,
inserted: 0,
position: 0,
len: base_len + self.insertions.len(),
})
}
}
pub(crate) struct Decode<'a> {
base: core::str::Chars<'a>,
pub(crate) insertions: &'a [(usize, char)],
inserted: usize,
position: usize,
len: usize,
}
impl<'a> Iterator for Decode<'a> {
type Item = char;
fn next(&mut self) -> Option<Self::Item> {
loop {
match self.insertions.get(self.inserted) {
Some((pos, c)) if *pos == self.position => {
self.inserted += 1;
self.position += 1;
return Some(*c);
}
_ => {}
}
if let Some(c) = self.base.next() {
self.position += 1;
return Some(c);
} else if self.inserted >= self.insertions.len() {
return None;
}
}
}
fn size_hint(&self) -> (usize, Option<usize>) {
let len = self.len - self.position;
(len, Some(len))
}
}
impl<'a> ExactSizeIterator for Decode<'a> {
fn len(&self) -> usize {
self.len - self.position
}
}
/// Convert an Unicode `str` to Punycode.
///
/// This is a convenience wrapper around `encode`.
#[inline]
pub fn encode_str(input: &str) -> Option<String> {
if input.len() > u32::MAX as usize {
return None;
}
let mut buf = String::with_capacity(input.len());
encode_into(input.chars(), &mut buf).ok().map(|()| buf)
}
/// Convert Unicode to Punycode.
///
/// Return None on overflow, which can only happen on inputs that would take more than
/// 63 encoded bytes, the DNS limit on domain name labels.
pub fn encode(input: &[char]) -> Option<String> {
if input.len() > u32::MAX as usize {
return None;
}
let mut buf = String::with_capacity(input.len());
encode_into(input.iter().copied(), &mut buf)
.ok()
.map(|()| buf)
}
pub(crate) fn encode_into<I>(input: I, output: &mut String) -> Result<(), ()>
where
I: Iterator<Item = char> + Clone,
{
// Handle "basic" (ASCII) code points. They are encoded as-is.
let (mut input_length, mut basic_length) = (0u32, 0);
for c in input.clone() {
input_length = input_length.checked_add(1).ok_or(())?;
if c.is_ascii() {
output.push(c);
basic_length += 1;
}
}
if basic_length > 0 {
output.push('-')
}
let mut code_point = INITIAL_N;
let mut delta = 0;
let mut bias = INITIAL_BIAS;
let mut processed = basic_length;
while processed < input_length {
// All code points < code_point have been handled already.
// Find the next larger one.
let min_code_point = input
.clone()
.map(|c| c as u32)
.filter(|&c| c >= code_point)
.min()
.unwrap();
if min_code_point - code_point > (u32::MAX - delta) / (processed + 1) {
return Err(()); // Overflow
}
// Increase delta to advance the decoder’s <code_point,i> state to <min_code_point,0>
delta += (min_code_point - code_point) * (processed + 1);
code_point = min_code_point;
for c in input.clone() {
let c = c as u32;
if c < code_point {
delta = delta.checked_add(1).ok_or(())?;
}
if c == code_point {
// Represent delta as a generalized variable-length integer:
let mut q = delta;
let mut k = BASE;
loop {
let t = if k <= bias {
T_MIN
} else if k >= bias + T_MAX {
T_MAX
} else {
k - bias
};
if q < t {
break;
}
let value = t + ((q - t) % (BASE - t));
output.push(value_to_digit(value));
q = (q - t) / (BASE - t);
k += BASE;
}
output.push(value_to_digit(q));
bias = adapt(delta, processed + 1, processed == basic_length);
delta = 0;
processed += 1;
}
}
delta += 1;
code_point += 1;
}
Ok(())
}
#[inline]
fn value_to_digit(value: u32) -> char {
match value {
0..=25 => (value as u8 + b'a') as char, // a..z
26..=35 => (value as u8 - 26 + b'0') as char, // 0..9
_ => panic!(),
}
}
#[test]
#[ignore = "slow"]
#[cfg(target_pointer_width = "64")]
fn huge_encode() {
let mut buf = String::new();
assert!(encode_into(std::iter::repeat('ß').take(u32::MAX as usize + 1), &mut buf).is_err());
assert_eq!(buf.len(), 0);
}