Hello community, I have been working with alot of IPv6 lately. Now i was wondering of what there might be the best way to validate an IPv6 address. Couldn't think of any working regexp, since even ::1 or :: is valid (localhost), so i tried it the following way: <?php //RFC 4291 //http://tools.ietf.org/html/rfc4291 function validate_ipv6($value) { if (substr_count($value, ":") < 2) return false; // has to contain ":" at least twice like in ::1 or 1234::abcd if (substr_count($value, "::") > 1) return false; // only 1 double colon allowed $groups = explode(':', $value); $num_groups = count($groups); if (($num_groups > 8) || ($num_groups < 3)) return false; // 3-8 groups of 0-4 digits (1 group has to be at leas 1 digit) $empty_groups = 0; foreach ($groups as $group) { $group = trim($group); if (!empty($group) && !(is_numeric($group) && ($group == 0))) { if (!preg_match('#([a-fA-F0-9]{0,4})#', $group)) return false; } else ++$empty_groups; } return ($empty_groups < $num_groups) ? true : false; // the unspecified address :: is not valid in this case } var_dump(validate_ipv6("::")); // false (wanted result) var_dump(validate_ipv6("::1")); // true var_dump(validate_ipv6("1234::abcd")); // true var_dump(validate_ipv6("2001:DB8:0:0:8:800:200C:417A")); // true var_dump(validate_ipv6("0:0:0:0:0:0:0:1")); // true var_dump(validate_ipv6("0:0:0:0:0:0:0:0")); // false (wanted result) var_dump(validate_ipv6("0000:0000:0000:0000:0000:0000:0000:0000")); // false (wanted result) var_dump(validate_ipv6("2001:0DB8:0000:CD30:0000:0000:0000:0000")); // true var_dump(validate_ipv6("FF01:0:0:0:0:0:0:101")); // true var_dump(validate_ipv6("bananas")); // false var_dump(validate_ipv6("1:2:3:4:5:6:7:8:9")); // false ?> anybody with better ideas? Yeti
