idn_to_utf8

(PHP 5 >= 5.3.0, PHP 7, PHP 8, PECL intl >= 1.0.2, PECL idn >= 0.1)

idn_to_utf8 — Convert domain name from IDNA ASCII to Unicode

Description

Procedural style

idn_to_utf8(
string $domain,
int $flags = IDNA_DEFAULT ,
int $variant = INTL_IDNA_VARIANT_UTS46 ,
array &$idna_info = null
): string |false

This function converts a Unicode domain name from an IDNA ASCII-compatible format to plain Unicode, encoded in UTF-8.

Parameters

domain: Domain to convert in an IDNA ASCII-compatible format.
flags: Conversion options - combination of IDNA_* constants (except IDNA_ERROR_* constants).
variant: Either INTL_IDNA_VARIANT_2003 (deprecated as of PHP 7.2.0) for IDNA 2003 or INTL_IDNA_VARIANT_UTS46 (only available as of ICU 4.6) for UTS #46.
idna_info: This parameter can be used only if INTL_IDNA_VARIANT_UTS46 was used for variant. In that case, it will be filled with an array with the keys 'result', the possibly illegal result of the transformation, 'isTransitionalDifferent', a boolean indicating whether the usage of the transitional mechanisms of UTS #46 either has or would have changed the result and 'errors', which is an int representing a bitset of the error constants IDNA_ERROR_*.

Return Values

The domain name in Unicode, encoded in UTF-8, or false on failure

Changelog

Version	Description
7.4.0	The default value of `variant` is now `INTL_IDNA_VARIANT_UTS46` instead of the deprecated `INTL_IDNA_VARIANT_2003` .
7.2.0	`INTL_IDNA_VARIANT_2003` has been deprecated; use `INTL_IDNA_VARIANT_UTS46` instead.

Examples

Example #1 idn_to_utf8() example

<?php

echo idn_to_utf8('xn--tst-qla.de'); 

?>

The above example will output:

täst.de

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User Contributed Notes 1 note

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kushik.com ¶

12 years ago

<?php
// for those who has PHP older than version 5.3
class IDN {
 // adapt bias for punycode algorithm
 private static function punyAdapt(
 $delta,
 $numpoints,
 $firsttime
 ) {
 $delta = $firsttime ? $delta / 700 : $delta / 2; 
 $delta += $delta / $numpoints;
 for ($k = 0; $delta > 455; $k += 36)
 $delta = intval($delta / 35);
 return $k + (36 * $delta) / ($delta + 38);
 }
 
 // translate character to punycode number
 private static function decodeDigit($cp) {
 $cp = strtolower($cp);
 if ($cp >= 'a' && $cp <= 'z')
 return ord($cp) - ord('a');
 elseif ($cp >= '0' && $cp <= '9')
 return ord($cp) - ord('0')+26;
 }
 
 // make utf8 string from unicode codepoint number
 private static function utf8($cp) {
 if ($cp < 128) return chr($cp);
 if ($cp < 2048) 
 return chr(192+($cp >> 6)).chr(128+($cp & 63));
 if ($cp < 65536) return 
 chr(224+($cp >> 12)).
 chr(128+(($cp >> 6) & 63)).
 chr(128+($cp & 63));
 if ($cp < 2097152) return 
 chr(240+($cp >> 18)).
 chr(128+(($cp >> 12) & 63)).
 chr(128+(($cp >> 6) & 63)).
 chr(128+($cp & 63));
 // it should never get here 
 }
 
 // main decoding function
 private static function decodePart($input) {
 if (substr($input,0,4) != "xn--") // prefix check...
 return $input;
 $input = substr($input,4); // discard prefix
 $a = explode("-",$input);
 if (count($a) > 1) {
 $input = str_split(array_pop($a));
 $output = str_split(implode("-",$a));
 } else {
 $output = array();
 $input = str_split($input);
 }
 $n = 128; $i = 0; $bias = 72; // init punycode vars
 while (!empty($input)) {
 $oldi = $i;
 $w = 1;
 for ($k = 36;;$k += 36) {
 $digit = IDN::decodeDigit(array_shift($input));
 $i += $digit * $w;
 if ($k <= $bias) $t = 1;
 elseif ($k >= $bias + 26) $t = 26;
 else $t = $k - $bias;
 if ($digit < $t) break;
 $w *= intval(36 - $t);
 }
 $bias = IDN::punyAdapt(
 $i-$oldi,
 count($output)+1,
 $oldi == 0
 );
 $n += intval($i / (count($output) + 1));
 $i %= count($output) + 1;
 array_splice($output,$i,0,array(IDN::utf8($n)));
 $i++;
 }
 return implode("",$output);
 }
 
 public static function decodeIDN($name) {
 // split it, parse it and put it back together
 return 
 implode(
 ".",
 array_map("IDN::decodePart",explode(".",$name))
 );
 }
 
}
echo IDN::decodeIDN($_SERVER['HTTP_HOST']);
?>