PHP 8.4.0 Alpha 2 available for testing

idn_to_utf8

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

idn_to_utf8Convert 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

See Also

add a note

User Contributed Notes 1 note

up
7
kushik.com
11 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']);
?>
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