src/valid-hostname.php ➔ hostname()

Complexity

Conditions	15
Paths	22

Size

Total Lines	68
Code Lines	32

Duplication

Lines	0
Ratio	0 %

Importance

Changes

0

<?php
function hostname($string, $public = true, $dns = false, $allow_glob = false, &$errno = null)
{
    $string = mb_strtolower($string, 'UTF-8');

    $hostname_ascii = idn_to_ascii($string, 0, INTL_IDNA_VARIANT_2003);
    $hostname_utf8  = idn_to_utf8($string, 0, INTL_IDNA_VARIANT_2003);

    // lets verify it converted correctly
    // this will also verify:
    // * label length
    // * empty labels
    // * domain length
    if ($hostname_ascii === false || $hostname_ascii !== idn_to_ascii($hostname_utf8, 0, INTL_IDNA_VARIANT_2003) || $hostname_ascii === '') {
        $errno = VALID_HOSTNAME_ERROR_INVALID;
        return false;
    }

    $labels_ascii = explode('.', $hostname_ascii);
    $labels_utf8  = explode('.', $hostname_utf8);

    foreach ($labels_ascii as $n => $label) {

        // optionally allow globs
        if ($allow_glob && $label === '*') {
            continue;
        }

        // label is not allowed to start or end with hyphen
        if ($labels_utf8[$n]{0} === '-') {
            $errno = VALID_HOSTNAME_ERROR_LEADING_HYPHEN;
            return false;
        }

        if (mb_substr($labels_utf8[$n], -1, 1, 'UTF-8') === '-') {
            $errno = VALID_HOSTNAME_ERROR_TRAILING_HYPHEN;
            return false;
        }

        // label must only contain 0-9, a-z or -_
        // hotfix: temporarily allow underscore, ideally only subdomains are allowed to have underscores
        if (!preg_match('/^([a-z0-9_](-*[a-z0-9_])*)$/', $label)) {
            $errno = VALID_HOSTNAME_ERROR_DISALLOWED;
            return false;
        }
    }

    // check if domain is in the public domain
    if ($public) {
        // at least two labels are required (SLD + TLD)
        if (substr_count($hostname_ascii, '.') === 0) {
            $errno = VALID_HOSTNAME_ERROR_NOTPUBLIC;
            return false;
        }

        if (!tld(substr(strrchr($hostname_ascii, '.'), 1))) {
            $errno = VALID_HOSTNAME_ERROR_NOTPUBLIC;
            return false;
        }
    }

    // check for dns
    if ($dns && gethostbyname($hostname_ascii . '.') === $hostname_ascii . '.') {
        $errno = VALID_HOSTNAME_ERROR_NODNS;
        return false;
    }

    return true;
}