balmet.com

IDNAEncoder.php (11547B)

---

 <?php
 
 /**
  * IDNA URL encoder
  *
  * Note: Not fully compliant, as nameprep does nothing yet.
  *
  * @package Requests
  * @subpackage Utilities
  * @see https://tools.ietf.org/html/rfc3490 IDNA specification
  * @see https://tools.ietf.org/html/rfc3492 Punycode/Bootstrap specification
  */
 class Requests_IDNAEncoder {
 	/**
 	 * ACE prefix used for IDNA
 	 *
 	 * @see https://tools.ietf.org/html/rfc3490#section-5
 	 * @var string
 	 */
 	const ACE_PREFIX = 'xn--';
 
 	/**#@+
 	 * Bootstrap constant for Punycode
 	 *
 	 * @see 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 $string Hostname
 	 * @return string Punycode-encoded hostname
 	 */
 	public static function encode($string) {
 		$parts = explode('.', $string);
 		foreach ($parts as &$part) {
 			$part = self::to_ascii($part);
 		}
 		return implode('.', $parts);
 	}
 
 	/**
 	 * Convert a UTF-8 string to an ASCII string using Punycode
 	 *
 	 * @throws Requests_Exception Provided string longer than 64 ASCII characters (`idna.provided_too_long`)
 	 * @throws Requests_Exception Prepared string longer than 64 ASCII characters (`idna.prepared_too_long`)
 	 * @throws Requests_Exception Provided string already begins with xn-- (`idna.provided_is_prefixed`)
 	 * @throws Requests_Exception Encoded string longer than 64 ASCII characters (`idna.encoded_too_long`)
 	 *
 	 * @param string $string ASCII or UTF-8 string (max length 64 characters)
 	 * @return string ASCII string
 	 */
 	public static function to_ascii($string) {
 		// Step 1: Check if the string is already ASCII
 		if (self::is_ascii($string)) {
 			// Skip to step 7
 			if (strlen($string) < 64) {
 				return $string;
 			}
 
 			throw new Requests_Exception('Provided string is too long', 'idna.provided_too_long', $string);
 		}
 
 		// Step 2: nameprep
 		$string = self::nameprep($string);
 
 		// Step 3: UseSTD3ASCIIRules is false, continue
 		// Step 4: Check if it's ASCII now
 		if (self::is_ascii($string)) {
 			// Skip to step 7
 			if (strlen($string) < 64) {
 				return $string;
 			}
 
 			throw new Requests_Exception('Prepared string is too long', 'idna.prepared_too_long', $string);
 		}
 
 		// Step 5: Check ACE prefix
 		if (strpos($string, self::ACE_PREFIX) === 0) {
 			throw new Requests_Exception('Provided string begins with ACE prefix', 'idna.provided_is_prefixed', $string);
 		}
 
 		// Step 6: Encode with Punycode
 		$string = self::punycode_encode($string);
 
 		// Step 7: Prepend ACE prefix
 		$string = self::ACE_PREFIX . $string;
 
 		// Step 8: Check size
 		if (strlen($string) < 64) {
 			return $string;
 		}
 
 		throw new Requests_Exception('Encoded string is too long', 'idna.encoded_too_long', $string);
 	}
 
 	/**
 	 * Check whether a given string contains only ASCII characters
 	 *
 	 * @internal (Testing found regex was the fastest implementation)
 	 *
 	 * @param string $string
 	 * @return bool Is the string ASCII-only?
 	 */
 	protected static function is_ascii($string) {
 		return (preg_match('/(?:[^\x00-\x7F])/', $string) !== 1);
 	}
 
 	/**
 	 * Prepare a string for use as an IDNA name
 	 *
 	 * @todo Implement this based on RFC 3491 and the newer 5891
 	 * @param string $string
 	 * @return string Prepared string
 	 */
 	protected static function nameprep($string) {
 		return $string;
 	}
 
 	/**
 	 * Convert a UTF-8 string to a UCS-4 codepoint array
 	 *
 	 * Based on Requests_IRI::replace_invalid_with_pct_encoding()
 	 *
 	 * @throws Requests_Exception Invalid UTF-8 codepoint (`idna.invalidcodepoint`)
 	 * @param string $input
 	 * @return array Unicode code points
 	 */
 	protected static function utf8_to_codepoints($input) {
 		$codepoints = array();
 
 		// 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]);
 
 			// One byte sequence:
 			if ((~$value & 0x80) === 0x80) {
 				$character = $value;
 				$length    = 1;
 				$remaining = 0;
 			}
 			// Two byte sequence:
 			elseif (($value & 0xE0) === 0xC0) {
 				$character = ($value & 0x1F) << 6;
 				$length    = 2;
 				$remaining = 1;
 			}
 			// Three byte sequence:
 			elseif (($value & 0xF0) === 0xE0) {
 				$character = ($value & 0x0F) << 12;
 				$length    = 3;
 				$remaining = 2;
 			}
 			// Four byte sequence:
 			elseif (($value & 0xF8) === 0xF0) {
 				$character = ($value & 0x07) << 18;
 				$length    = 4;
 				$remaining = 3;
 			}
 			// Invalid byte:
 			else {
 				throw new Requests_Exception('Invalid Unicode codepoint', 'idna.invalidcodepoint', $value);
 			}
 
 			if ($remaining > 0) {
 				if ($position + $length > $strlen) {
 					throw new Requests_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 Requests_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 Requests_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
 	 * @throws Requests_Exception On character outside of the domain (never happens with Punycode) (`idna.character_outside_domain`)
 	 *
 	 * @param string $input UTF-8 encoded string to encode
 	 * @return string Punycode-encoded string
 	 */
 	public static function punycode_encode($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   = array();
 
 		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 Requests_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) {
 					$delta++;
 				}
 				// if c == n then begin
 				elseif ($c === $n) {
 					// 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   = $t + (($q - $t) % (self::BOOTSTRAP_BASE - $t));
 						$output .= self::digit_to_char($digit);
 						// let q = (q - t) div (base - t)
 						$q = floor(($q - $t) / (self::BOOTSTRAP_BASE - $t));
 					} // end
 					// 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++;
 				} // end
 			} // end
 			// increment delta and n
 			$delta++;
 			$n++;
 		} // end
 
 		return $output;
 	}
 
 	/**
 	 * Convert a digit to its respective character
 	 *
 	 * @see https://tools.ietf.org/html/rfc3492#section-5
 	 * @throws Requests_Exception On invalid digit (`idna.invalid_digit`)
 	 *
 	 * @param int $digit Digit in the range 0-35
 	 * @return string Single character corresponding to digit
 	 */
 	protected static function digit_to_char($digit) {
 		// @codeCoverageIgnoreStart
 		// As far as I know, this never happens, but still good to be sure.
 		if ($digit < 0 || $digit > 35) {
 			throw new Requests_Exception(sprintf('Invalid digit %d', $digit), 'idna.invalid_digit', $digit);
 		}
 		// @codeCoverageIgnoreEnd
 		$digits = 'abcdefghijklmnopqrstuvwxyz0123456789';
 		return substr($digits, $digit, 1);
 	}
 
 	/**
 	 * Adapt the bias
 	 *
 	 * @see https://tools.ietf.org/html/rfc3492#section-6.1
 	 * @param int $delta
 	 * @param int $numpoints
 	 * @param bool $firsttime
 	 * @return int New bias
 	 *
 	 * function adapt(delta,numpoints,firsttime):
 	 */
 	protected static function adapt($delta, $numpoints, $firsttime) {
 		// if firsttime then let delta = delta div damp
 		if ($firsttime) {
 			$delta = floor($delta / self::BOOTSTRAP_DAMP);
 		}
 		// else let delta = delta div 2
 		else {
 			$delta = floor($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;
 		} // end
 		// return k + (((base - tmin + 1) * delta) div (delta + skew))
 		return $k + floor(((self::BOOTSTRAP_BASE - self::BOOTSTRAP_TMIN + 1) * $delta) / ($delta + self::BOOTSTRAP_SKEW));
 	}
 }