/**
* Checks whether the given host name is valid according to the syntax defined
* in RFC-3986.
*
* Note that a valid host name is not restricted to be a valid IPv4, IPv6 or
* domain name. The valid syntax is much more abstract.
*
* Returns TRUE in case the given host name is valid.
* Otherwise returns FALSE.
*
* @param string $host The host name to check
* @return bool
*/
public static function isValidHost($host)
{
// check whether a string is given
if (!is_string($host)) {
return false;
}
// remove surrounding square brackets from host name
$host = StringUtil::removeEnclosingCharacters($host, '[', ']');
// check for registered name (also covers IPv4 addresses)
if (preg_match('/^(?:[' . self::CHARS_UNRESERVED . self::CHARS_SUB_DELIMITERS . ']+|%[[:xdigit:]]{2})+$/', $host)) {
return true;
}
// check for IPv6
if (filter_var($host, FILTER_VALIDATE_IP, FILTER_FLAG_IPV6) !== false) {
return true;
}
// check for IPvFuture
if (preg_match('/^v[[:xdigit:]]+\\.[' . self::CHARS_UNRESERVED . self::CHARS_SUB_DELIMITERS . ':]+$/', $host)) {
return true;
}
// not a valid host
return false;
}
