idn_to_utf8

<?php// for those who has PHP older than version 5.3class 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']);?>