<?php

/**

* Requests for PHP, an HTTP library.

*

* @copyright 2012-2023 Requests Contributors

* @license https://github.com/WordPress/Requests/blob/stable/LICENSE ISC

* @link https://github.com/WordPress/Requests

*/

namespace WpOrg\Requests;

use WpOrg\Requests\Exception;

use WpOrg\Requests\Exception\InvalidArgument;

use WpOrg\Requests\Utility\InputValidator;

/**

* IDNA URL encoder

*

* Note: Not fully compliant, as nameprep does nothing yet.

*

* @package Requests\Utilities

*

* @link https://tools.ietf.org/html/rfc3490 IDNA specification

* @link https://tools.ietf.org/html/rfc3492 Punycode/Bootstrap specification

*/

class IdnaEncoder {

/**

* ACE prefix used for IDNA

*

* @link https://tools.ietf.org/html/rfc3490#section-5

* @var string

*/

const ACE_PREFIX = 'xn--';

/**

* Maximum length of a IDNA URL in ASCII.

*

* @see \WpOrg\Requests\IdnaEncoder::to_ascii()

*

* @since 2.0.0

*

* @var int

*/

const MAX_LENGTH = 64;

/**#@+

* Bootstrap constant for Punycode

*

* @link https://tools.ietf.org/html/rfc3492#section-5

* @var int

*/

const BOOTSTRAP_BASE = 36;

const BOOTSTRAP_TMIN = 1;

const BOOTSTRAP_TMAX = 26;

const BOOTSTRAP_SKEW = 38;

const BOOTSTRAP_DAMP = 700;

const BOOTSTRAP_INITIAL_BIAS = 72;

const BOOTSTRAP_INITIAL_N = 128;

/**#@-*/

/**

* Encode a hostname using Punycode

*

* @param string|\Stringable $hostname Hostname

* @return string Punycode-encoded hostname

* @throws \WpOrg\Requests\Exception\InvalidArgument When the passed argument is not a string or a stringable object.

*/

public static function encode($hostname) {

if (InputValidator::is_string_or_stringable($hostname) === false) {

throw InvalidArgument::create(1, '$hostname', 'string|Stringable', gettype($hostname));

}

$parts = explode('.', $hostname);

foreach ($parts as &$part) {

$part = self::to_ascii($part);

}

return implode('.', $parts);

}

/**

* Convert a UTF-8 text string to an ASCII string using Punycode

*

* @param string $text ASCII or UTF-8 string (max length 64 characters)

* @return string ASCII string

*

* @throws \WpOrg\Requests\Exception Provided string longer than 64 ASCII characters (`idna.provided_too_long`)

* @throws \WpOrg\Requests\Exception Prepared string longer than 64 ASCII characters (`idna.prepared_too_long`)

* @throws \WpOrg\Requests\Exception Provided string already begins with xn-- (`idna.provided_is_prefixed`)

* @throws \WpOrg\Requests\Exception Encoded string longer than 64 ASCII characters (`idna.encoded_too_long`)

*/

public static function to_ascii($text) {

// Step 1: Check if the text is already ASCII

if (self::is_ascii($text)) {

// Skip to step 7

if (strlen($text) < self::MAX_LENGTH) {

return $text;

}

throw new Exception('Provided string is too long', 'idna.provided_too_long', $text);

}

// Step 2: nameprep

$text = self::nameprep($text);

// Step 3: UseSTD3ASCIIRules is false, continue

// Step 4: Check if it's ASCII now

if (self::is_ascii($text)) {

// Skip to step 7

/*

* As the `nameprep()` method returns the original string, this code will never be reached until

* that method is properly implemented.

*/

// @codeCoverageIgnoreStart

if (strlen($text) < self::MAX_LENGTH) {

return $text;

}

throw new Exception('Prepared string is too long', 'idna.prepared_too_long', $text);

// @codeCoverageIgnoreEnd

}

// Step 5: Check ACE prefix

if (strpos($text, self::ACE_PREFIX) === 0) {

throw new Exception('Provided string begins with ACE prefix', 'idna.provided_is_prefixed', $text);

}

// Step 6: Encode with Punycode

$text = self::punycode_encode($text);

// Step 7: Prepend ACE prefix

$text = self::ACE_PREFIX . $text;

// Step 8: Check size

if (strlen($text) < self::MAX_LENGTH) {

return $text;

}

throw new Exception('Encoded string is too long', 'idna.encoded_too_long', $text);

}

/**

* Check whether a given text string contains only ASCII characters

*

* @internal (Testing found regex was the fastest implementation)

*

* @param string $text Text to examine.

* @return bool Is the text string ASCII-only?

*/

protected static function is_ascii($text) {

return (preg_match('/(?:[^\x00-\x7F])/', $text) !== 1);

}

/**

* Prepare a text string for use as an IDNA name

*

* @todo Implement this based on RFC 3491 and the newer 5891

* @param string $text Text to prepare.

* @return string Prepared string

*/

protected static function nameprep($text) {

return $text;

}

/**

* Convert a UTF-8 string to a UCS-4 codepoint array

*

* Based on \WpOrg\Requests\Iri::replace_invalid_with_pct_encoding()

*

* @param string $input Text to convert.

* @return array Unicode code points

*

* @throws \WpOrg\Requests\Exception Invalid UTF-8 codepoint (`idna.invalidcodepoint`)

*/

protected static function utf8_to_codepoints($input) {

$codepoints = [];

// Get number of bytes

$strlen = strlen($input);

// phpcs:ignore Generic.CodeAnalysis.JumbledIncrementer -- This is a deliberate choice.

for ($position = 0; $position < $strlen; $position++) {

$value = ord($input[$position]);

if ((~$value & 0x80) === 0x80) { // One byte sequence:

$character = $value;

$length = 1;

$remaining = 0;

} elseif (($value & 0xE0) === 0xC0) { // Two byte sequence:

$character = ($value & 0x1F) << 6;

$length = 2;

$remaining = 1;

} elseif (($value & 0xF0) === 0xE0) { // Three byte sequence:

$character = ($value & 0x0F) << 12;

$length = 3;

$remaining = 2;

} elseif (($value & 0xF8) === 0xF0) { // Four byte sequence:

$character = ($value & 0x07) << 18;

$length = 4;

$remaining = 3;

} else { // Invalid byte:

throw new Exception('Invalid Unicode codepoint', 'idna.invalidcodepoint', $value);

}

if ($remaining > 0) {

if ($position + $length > $strlen) {

throw new Exception('Invalid Unicode codepoint', 'idna.invalidcodepoint', $character);

}

for ($position++; $remaining > 0; $position++) {

$value = ord($input[$position]);

// If it is invalid, count the sequence as invalid and reprocess the current byte:

if (($value & 0xC0) !== 0x80) {

throw new Exception('Invalid Unicode codepoint', 'idna.invalidcodepoint', $character);

}

--$remaining;

$character |= ($value & 0x3F) << ($remaining * 6);

}

--$position;

}

if (// Non-shortest form sequences are invalid

($length > 1 && $character <= 0x7F)

|| ($length > 2 && $character <= 0x7FF)

|| ($length > 3 && $character <= 0xFFFF)

// Outside of range of ucschar codepoints

// Noncharacters

|| ($character & 0xFFFE) === 0xFFFE

|| ($character >= 0xFDD0 && $character <= 0xFDEF)

|| (

// Everything else not in ucschar

($character > 0xD7FF && $character < 0xF900)

|| $character < 0x20

|| ($character > 0x7E && $character < 0xA0)

|| $character > 0xEFFFD

)

) {

throw new Exception('Invalid Unicode codepoint', 'idna.invalidcodepoint', $character);

}

$codepoints[] = $character;

}

return $codepoints;

}

/**

* RFC3492-compliant encoder

*

* @internal Pseudo-code from Section 6.3 is commented with "#" next to relevant code

*

* @param string $input UTF-8 encoded string to encode

* @return string Punycode-encoded string

*

* @throws \WpOrg\Requests\Exception On character outside of the domain (never happens with Punycode) (`idna.character_outside_domain`)

*/

public static function punycode_encode($input) {

$output = '';

// let n = initial_n

$n = self::BOOTSTRAP_INITIAL_N;

// let delta = 0

$delta = 0;

// let bias = initial_bias

$bias = self::BOOTSTRAP_INITIAL_BIAS;

// let h = b = the number of basic code points in the input

$h = 0;

$b = 0; // see loop

// copy them to the output in order

$codepoints = self::utf8_to_codepoints($input);

$extended = [];

foreach ($codepoints as $char) {

if ($char < 128) {

// Character is valid ASCII

// TODO: this should also check if it's valid for a URL

$output .= chr($char);

++$h;

// Check if the character is non-ASCII, but below initial n

// This never occurs for Punycode, so ignore in coverage

// @codeCoverageIgnoreStart

} elseif ($char < $n) {

throw new Exception('Invalid character', 'idna.character_outside_domain', $char);

// @codeCoverageIgnoreEnd

} else {

$extended[$char] = true;

}

}

$extended = array_keys($extended);

sort($extended);

$b = $h;

// [copy them] followed by a delimiter if b > 0

if (strlen($output) > 0) {

$output .= '-';

}

// {if the input contains a non-basic code point < n then fail}

// while h < length(input) do begin

$codepointcount = count($codepoints);

while ($h < $codepointcount) {

// let m = the minimum code point >= n in the input

$m = array_shift($extended);

//printf('next code point to insert is %s' . PHP_EOL, dechex($m));

// let delta = delta + (m - n) * (h + 1), fail on overflow

$delta += ($m - $n) * ($h + 1);

// let n = m

$n = $m;

// for each code point c in the input (in order) do begin

for ($num = 0; $num < $codepointcount; $num++) {

$c = $codepoints[$num];

// if c < n then increment delta, fail on overflow

if ($c < $n) {

++$delta;

} elseif ($c === $n) { // if c == n then begin

// let q = delta

$q = $delta;

// for k = base to infinity in steps of base do begin

for ($k = self::BOOTSTRAP_BASE; ; $k += self::BOOTSTRAP_BASE) {

// let t = tmin if k <= bias {+ tmin}, or

// tmax if k >= bias + tmax, or k - bias otherwise

if ($k <= ($bias + self::BOOTSTRAP_TMIN)) {

$t = self::BOOTSTRAP_TMIN;

} elseif ($k >= ($bias + self::BOOTSTRAP_TMAX)) {

$t = self::BOOTSTRAP_TMAX;

} else {

$t = $k - $bias;

}

// if q < t then break

if ($q < $t) {

break;

}

// output the code point for digit t + ((q - t) mod (base - t))

$digit = (int) ($t + (($q - $t) % (self::BOOTSTRAP_BASE - $t)));

$output .= self::digit_to_char($digit);

// let q = (q - t) div (base - t)

$q = (int) floor(($q - $t) / (self::BOOTSTRAP_BASE - $t));

}

// output the code point for digit q

$output .= self::digit_to_char($q);

// let bias = adapt(delta, h + 1, test h equals b?)

$bias = self::adapt($delta, $h + 1, $h === $b);

// let delta = 0

$delta = 0;

// increment h

++$h;

}

}

// increment delta and n

++$delta;

++$n;

}

return $output;

}

/**

* Convert a digit to its respective character

*

* @link https://tools.ietf.org/html/rfc3492#section-5

*

* @param int $digit Digit in the range 0-35

* @return string Single character corresponding to digit

*

* @throws \WpOrg\Requests\Exception On invalid digit (`idna.invalid_digit`)

*/

protected static function digit_to_char($digit) {

// @codeCoverageIgnoreStart

// As far as I know, this never happens, but still good to be sure.

if ($digit < 0 || $digit > 35) {

throw new Exception(sprintf('Invalid digit %d', $digit), 'idna.invalid_digit', $digit);

}

// @codeCoverageIgnoreEnd

$digits = 'abcdefghijklmnopqrstuvwxyz0123456789';

return substr($digits, $digit, 1);

}

/**

* Adapt the bias

*

* @link https://tools.ietf.org/html/rfc3492#section-6.1

* @param int $delta

* @param int $numpoints

* @param bool $firsttime

* @return int|float New bias

*/

protected static function adapt($delta, $numpoints, $firsttime) {

// if firsttime then let delta = delta div damp

if ($firsttime) {

$delta = floor($delta / self::BOOTSTRAP_DAMP);

} else {

// else let delta = delta div 2

$delta = floor($delta / 2);

}

// let delta = delta + (delta div numpoints)

$delta += floor($delta / $numpoints);

// let k = 0

$k = 0;

// while delta > ((base - tmin) * tmax) div 2 do begin

$max = floor(((self::BOOTSTRAP_BASE - self::BOOTSTRAP_TMIN) * self::BOOTSTRAP_TMAX) / 2);

while ($delta > $max) {

// let delta = delta div (base - tmin)

$delta = floor($delta / (self::BOOTSTRAP_BASE - self::BOOTSTRAP_TMIN));

// let k = k + base

$k += self::BOOTSTRAP_BASE;

}

// return k + (((base - tmin + 1) * delta) div (delta + skew))

return $k + floor(((self::BOOTSTRAP_BASE - self::BOOTSTRAP_TMIN + 1) * $delta) / ($delta + self::BOOTSTRAP_SKEW));

}

}