<?php
	function check_domainname($domainname, $typelist = [] /* any one will do */) {
		if (!preg_match("/^([.][a-z0-9][-_a-z0-9]*)+$/i", '.'.$domainname))
			return false;

		if (!is_array($typelist))
			do_die("typelist must be an array");
		if (count($typelist) == 0)
			return true;

		foreach ($typelist as $t) {
			$rr = dns_get_record($domainname, $t);
			if (is_array($rr) && count($rr) > 0)
				return true;
		}

		return false;
	}

	function normalize_ip($ip) {
		if (validate_ip4($ip))
			return $ip;
		if (validate_ip6($ip)) {
			/* trim leading zeroes in any given 4-nibble word. */
			$ip = preg_replace("/(^|:)0+([a-fA-F0-9])/", "\\1\\2", $ip);
			$parts = explode("::", $ip);
			if (count($parts) == 1)
				return $ip;
			/* :: can be both leading and trailing */
			if (!$parts[0]) /* leading :: */
				$parts[0] = "0";
			if (!$parts[1]) /* trailing :: */
				$parts[1] = "0";
			$ccount = count(explode(":", $parts[0])) + count(explode(":", $parts[1]));
			$ins = ":";
			while ($ccount++ < 8)
				$ins .= "0:";
			return $parts[0].$ins.$parts[1];
		}
		return NULL;
	}

	function ip_version($ip) {
		if (validate_ip4($ip))
			return 4;
		if (validate_ip6($ip))
			return 6;
		return false;
	}

	function validate_ip($ip) {
		return validate_ip4($ip) || validate_ip6($ip);
	}

	function validate_ip4($ip) {
		return ip2long($ip) !== FALSE;
	}

	function validate_ip6($ip) {
		$double = false;
		$ip = strtolower($ip);
		$parts = explode(':', $ip);
		if (count($parts) > 8)
			/* IPv6 addresses comes in blocks of 4-nibble blocks of 16 bits, or 8 blocks */
			return false;
		if (count($parts) == 1)
			/* Want at least one : */
			return false;

		/* Special case of leading :: */
		if (count($parts) > 1 && !$parts[0]) {
			if (!$parts[1]) {
				array_shift($parts);
				array_shift($parts);
				$double = true;

				if (count($parts) == 0)
					return false; /* : is not valid */

				if (count($parts) == 1 && $parts[0] == "")
					return true; /* :: is "any", which is legal/valid. */
			} else {
				/* Address starting with :something - invalid? */
				return false;
			}
		}
		if (count($parts) > 1 && !$parts[count($parts) - 1]) {
			if ($parts[count($parts) - 2]) {
				/* Address ending with :something - invalid? */
				return false;
			} else {
				if ($double)
					return false;
				array_pop($parts);
				array_pop($parts);
				$double = true;
			}
		}

		foreach ($parts as $p) {
			if ($p == "") {
				/* :: use-case, or fill out with zeroes */
				if ($double) {
					return false; /* only one such allowed */
				}
				$double = true;
			} else if (!preg_match('/^[0-9a-f]{1,4}$/', $p)) {
				return false;
			}
		}

		if (!$double && count($parts) < 8)
			return false; /* Unless a :: we should have exactly 8 blocks */
		return true;
	}

	function ip2range($range)
	{
		if (preg_match(",^([0-9.]+)/([0-9]+)$,", $range, $p)) {
			$ip = ip2long($p[1]);
			$mask = $p[2];
			if ($ip === FALSE || $mask > 32)
				return [NULL, NULL, NULL];
			$rangesize = pow(2, 32-$mask);
			$ip &= 0xFFFFFFFF & ~($rangesize-1);
			return [long2ip($ip), long2ip($ip - 1 + $rangesize), $mask];
		} elseif (preg_match(",^([0-9.]+)-([0-9.]+)$,", $range, $p)) {
			$ip1 = ip2long($p[1]);
			$ip2 = ip2long($p[2]);
			if ($ip1 === FALSE || $ip2 === FALSE)
				return [NULL, NULL];
			if ($ip1 > $ip2) {
				$ip1 ^= $ip2;
				$ip2 ^= $ip1;
				$ip1 ^= $ip2;
			}
			// See if we can calulate some matching mask.
			$mask = 0xFFFFFFFF;
			$msize = 0;

			while (($ip1 & $mask) != 0) {
				$mask >>= 1;
				$msize++;
			}
			while (($ip2 & $mask) != $mask) {
				$mask >>= 1;
				$msize++;
			}

			if (($ip1 | $mask) != $ip2)
				$msize = NULL;

			return [long2ip($ip1), long2ip($ip2), $msize];
		} else
			return [NULL, NULL];
	}

	/* assume the string is a valid IP address */
	function ip_is_private($ipaddress)
	{
		return preg_match("/^(192[.]168[.]|10[.]|172[.](1[2-9]|2[0-9]|3[01])[.]|f[cd]00:)/",
			$ipaddress);
	}

	function ip_is_lsn($ipaddress)
	{
		return preg_match("/^100[.](6[4-9]|[7-9][0-9]|1[01][0-9]|12[0-7])[.]/", $ipaddress);
	}

	function ip_is_localhost($ipaddress)
	{
		return preg_match("/^(127[.]|::1$)/", $ipaddress);
	}

	function ip_is_multicast($ipaddress)
	{
		return preg_match("/^(ff[^:]{2}:|22[4-9][.]|23[0-9][.])/", $ipaddress);
	}

	function ip_is_linklocal($ipaddress)
	{
		return preg_match("/^(169[.]254[.]|fe80::)/", $ipaddress);
	}

	function ip_is_public($ipaddress)
	{
		return !ip_is_localhost($ipaddress) &&
			!ip_is_private($ipaddress) &&
			!ip_is_linklocal($ipaddress) &&
			!ip_is_multicast($ipaddress) &&
		   	!ip_is_lsn($ipaddress);
	}

	function ip_is_v4mappedv6($ipaddress) {
		if (preg_match("/^::ffff:([0-9.]+)$/", $ipaddress, $p) && validate_ip4($p[1]))
			return $p[1];
		return false;
	}

	function ip_unmapped($ipaddress)
	{
		return ip_is_v4mappedv6($ipaddress) ?: $ipaddress;
	}

	function ip_mapped($ipaddress)
	{
		if (validate_ip4($ipaddress))
			return "::ffff:".$ipaddress;
		if (validate_ip6($ipaddress))
			return $ipaddress;
		return NULL;
	}
?>