1 <?php

     2 

     3 namespace WpOrg\Requests;

     4 

     5 use WpOrg\Requests\Exception;

     6 use WpOrg\Requests\Exception\InvalidArgument;

     7 use WpOrg\Requests\Utility\InputValidator;

     8 

     9 /**

    10  * IDNA URL encoder

    11  *

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

    13  *

    14  * @package Requests\Utilities

    15  *

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

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

    18  */

    19 class IdnaEncoder {

    20 	/**

    21 	 * ACE prefix used for IDNA

    22 	 *

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

    24 	 * @var string

    25 	 */

    26 	const ACE_PREFIX = 'xn--';

    27 

    28 	/**

    29 	 * Maximum length of a IDNA URL in ASCII.

    30 	 *

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

    32 	 *

    33 	 * @since 2.0.0

    34 	 *

    35 	 * @var int

    36 	 */

    37 	const MAX_LENGTH = 64;

    38 

    39 	/**#@+

    40 	 * Bootstrap constant for Punycode

    41 	 *

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

    43 	 * @var int

    44 	 */

    45 	const BOOTSTRAP_BASE         = 36;

    46 	const BOOTSTRAP_TMIN         = 1;

    47 	const BOOTSTRAP_TMAX         = 26;

    48 	const BOOTSTRAP_SKEW         = 38;

    49 	const BOOTSTRAP_DAMP         = 700;

    50 	const BOOTSTRAP_INITIAL_BIAS = 72;

    51 	const BOOTSTRAP_INITIAL_N    = 128;

    52 	/**#@-*/

    53 

    54 	/**

    55 	 * Encode a hostname using Punycode

    56 	 *

    57 	 * @param string|Stringable $hostname Hostname

    58 	 * @return string Punycode-encoded hostname

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

    60 	 */

    61 	public static function encode($hostname) {

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

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

    64 		}

    65 

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

    67 		foreach ($parts as &$part) {

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

    69 		}

    70 

    71 		return implode('.', $parts);

    72 	}

    73 

    74 	/**

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

    76 	 *

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

    78 	 * @return string ASCII string

    79 	 *

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

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

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

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

    84 	 */

    85 	public static function to_ascii($text) {

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

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

    88 			// Skip to step 7

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

    90 				return $text;

    91 			}

    92 

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

    94 		}

    95 

    96 		// Step 2: nameprep

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

    98 

    99 		// Step 3: UseSTD3ASCIIRules is false, continue

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

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

   102 			// Skip to step 7

   103 			/*

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

   105 			 * that method is properly implemented.

   106 			 */

   107 			// @codeCoverageIgnoreStart

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

   109 				return $text;

   110 			}

   111 

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

   113 			// @codeCoverageIgnoreEnd

   114 		}

   115 

   116 		// Step 5: Check ACE prefix

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

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

   119 		}

   120 

   121 		// Step 6: Encode with Punycode

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

   123 

   124 		// Step 7: Prepend ACE prefix

   125 		$text = self::ACE_PREFIX . $text;

   126 

   127 		// Step 8: Check size

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

   129 			return $text;

   130 		}

   131 

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

   133 	}

   134 

   135 	/**

   136 	 * Check whether a given text string contains only ASCII characters

   137 	 *

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

   139 	 *

   140 	 * @param string $text Text to examine.

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

   142 	 */

   143 	protected static function is_ascii($text) {

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

   145 	}

   146 

   147 	/**

   148 	 * Prepare a text string for use as an IDNA name

   149 	 *

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

   151 	 * @param string $text Text to prepare.

   152 	 * @return string Prepared string

   153 	 */

   154 	protected static function nameprep($text) {

   155 		return $text;

   156 	}

   157 

   158 	/**

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

   160 	 *

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

   162 	 *

   163 	 * @param string $input Text to convert.

   164 	 * @return array Unicode code points

   165 	 *

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

   167 	 */

   168 	protected static function utf8_to_codepoints($input) {

   169 		$codepoints = [];

   170 

   171 		// Get number of bytes

   172 		$strlen = strlen($input);

   173 

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

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

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

   177 

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

   179 				$character = $value;

   180 				$length    = 1;

   181 				$remaining = 0;

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

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

   184 				$length    = 2;

   185 				$remaining = 1;

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

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

   188 				$length    = 3;

   189 				$remaining = 2;

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

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

   192 				$length    = 4;

   193 				$remaining = 3;

   194 			} else {                                    // Invalid byte:

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

   196 			}

   197 

   198 			if ($remaining > 0) {

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

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

   201 				}

   202 

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

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

   205 

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

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

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

   209 					}

   210 

   211 					--$remaining;

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

   213 				}

   214 

   215 				$position--;

   216 			}

   217 

   218 			if (// Non-shortest form sequences are invalid

   219 				$length > 1 && $character <= 0x7F

   220 				|| $length > 2 && $character <= 0x7FF

   221 				|| $length > 3 && $character <= 0xFFFF

   222 				// Outside of range of ucschar codepoints

   223 				// Noncharacters

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

   225 				|| $character >= 0xFDD0 && $character <= 0xFDEF

   226 				|| (

   227 					// Everything else not in ucschar

   228 					$character > 0xD7FF && $character < 0xF900

   229 					|| $character < 0x20

   230 					|| $character > 0x7E && $character < 0xA0

   231 					|| $character > 0xEFFFD

   232 				)

   233 			) {

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

   235 			}

   236 

   237 			$codepoints[] = $character;

   238 		}

   239 

   240 		return $codepoints;

   241 	}

   242 

   243 	/**

   244 	 * RFC3492-compliant encoder

   245 	 *

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

   247 	 *

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

   249 	 * @return string Punycode-encoded string

   250 	 *

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

   252 	 */

   253 	public static function punycode_encode($input) {

   254 		$output = '';

   255 		// let n = initial_n

   256 		$n = self::BOOTSTRAP_INITIAL_N;

   257 		// let delta = 0

   258 		$delta = 0;

   259 		// let bias = initial_bias

   260 		$bias = self::BOOTSTRAP_INITIAL_BIAS;

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

   262 		$h = 0;

   263 		$b = 0; // see loop

   264 		// copy them to the output in order

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

   266 		$extended   = [];

   267 

   268 		foreach ($codepoints as $char) {

   269 			if ($char < 128) {

   270 				// Character is valid ASCII

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

   272 				$output .= chr($char);

   273 				$h++;

   274 

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

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

   277 				// @codeCoverageIgnoreStart

   278 			} elseif ($char < $n) {

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

   280 				// @codeCoverageIgnoreEnd

   281 			} else {

   282 				$extended[$char] = true;

   283 			}

   284 		}

   285 

   286 		$extended = array_keys($extended);

   287 		sort($extended);

   288 		$b = $h;

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

   290 		if (strlen($output) > 0) {

   291 			$output .= '-';

   292 		}

   293 

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

   295 		// while h < length(input) do begin

   296 		$codepointcount = count($codepoints);

   297 		while ($h < $codepointcount) {

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

   299 			$m = array_shift($extended);

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

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

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

   303 			// let n = m

   304 			$n = $m;

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

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

   307 				$c = $codepoints[$num];

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

   309 				if ($c < $n) {

   310 					$delta++;

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

   312 					// let q = delta

   313 					$q = $delta;

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

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

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

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

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

   319 							$t = self::BOOTSTRAP_TMIN;

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

   321 							$t = self::BOOTSTRAP_TMAX;

   322 						} else {

   323 							$t = $k - $bias;

   324 						}

   325 

   326 						// if q < t then break

   327 						if ($q < $t) {

   328 							break;

   329 						}

   330 

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

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

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

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

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

   336 					} // end

   337 					// output the code point for digit q

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

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

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

   341 					// let delta = 0

   342 					$delta = 0;

   343 					// increment h

   344 					$h++;

   345 				} // end

   346 			} // end

   347 			// increment delta and n

   348 			$delta++;

   349 			$n++;

   350 		} // end

   351 

   352 		return $output;

   353 	}

   354 

   355 	/**

   356 	 * Convert a digit to its respective character

   357 	 *

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

   359 	 *

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

   361 	 * @return string Single character corresponding to digit

   362 	 *

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

   364 	 */

   365 	protected static function digit_to_char($digit) {

   366 		// @codeCoverageIgnoreStart

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

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

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

   370 		}

   371 

   372 		// @codeCoverageIgnoreEnd

   373 		$digits = 'abcdefghijklmnopqrstuvwxyz0123456789';

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

   375 	}

   376 

   377 	/**

   378 	 * Adapt the bias

   379 	 *

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

   381 	 * @param int $delta

   382 	 * @param int $numpoints

   383 	 * @param bool $firsttime

   384 	 * @return int|float New bias

   385 	 *

   386 	 * function adapt(delta,numpoints,firsttime):

   387 	 */

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

   389 		// if firsttime then let delta = delta div damp

   390 		if ($firsttime) {

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

   392 		} else {

   393 			// else let delta = delta div 2

   394 			$delta = floor($delta / 2);

   395 		}

   396 

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

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

   399 		// let k = 0

   400 		$k = 0;

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

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

   403 		while ($delta > $max) {

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

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

   406 			// let k = k + base

   407 			$k += self::BOOTSTRAP_BASE;

   408 		} // end

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

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

   411 	}

   412 }