然后,服务器接受IPv6套接字上的连接.某些操作系统可以在IPv6套接字上同时执行IPv4和IPv6.当发生这种情况时,IPv6地址看起来像:: ffff：192.0.2.123或:: ffff：c000：027b,它们是相同的地址但用十六进制编写.
如果您看到像2a00：8640：1 :: 224：36ff：feef：1d89这样的IPv6地址,那么您的网络服务器确实可通过IPv6访问:-)
- // Known prefix
- $v4mapped_prefix_hex = '00000000000000000000ffff';
- $v4mapped_prefix_bin = pack("H*",$v4mapped_prefix_hex);
- // Or more readable when using PHP >= 5.4
- # $v4mapped_prefix_bin = hex2bin($v4mapped_prefix_hex);
- // Parse
- $addr = $_SERVER['REMOTE_ADDR'];
- $addr_bin = inet_pton($addr);
- if( $addr_bin === FALSE ) {
- // Unparsable? How did they connect?!?
- die('Invalid IP address');
- }
- // Check prefix
- if( substr($addr_bin,strlen($v4mapped_prefix_bin)) == $v4mapped_prefix_bin) {
- // Strip prefix
- $addr_bin = substr($addr_bin,strlen($v4mapped_prefix_bin));
- }
- // Convert back to printable address in canonical form
- $addr = inet_ntop($addr_bin);
- ::ffff:192.000.002.123
- ::ffff:192.0.2.123
- 0000:0000:0000:0000:0000:ffff:c000:027b
- ::ffff:c000:027b
- ::ffff:c000:27b
- 192.000.002.123
- 192.0.2.123
你总是得到规范的IPv4地址192.0.2.123作为输出.
当然,IPv6地址作为规范的IPv6地址返回：2a00：8640：0001：0000：0224：36ff：feef：1d89变为2a00：8640：1 :: 224：36ff：feef：1d89等
