<?php
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));
} // 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
*
* @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 $firsttime
* @return int|float New bias
*
* function adapt(delta,numpoints,firsttime):
*/
protected static function adapt($delta, $numpoints, $firsttime) {
// if firsttime then let delta = delta div damp
if ($firsttime) {
$delta = floor($delta / self::BOOTSTRAP_DAMP);
} else {
// 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;
} // 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));
}
}