请问php怎么使用自己构造的IP包头

请教php如何使用自己构造的IP包头

PHP code

<!--Code highlighting produced by Actipro CodeHighlighter (freeware)http://www.CodeHighlighter.com/--><?php //数据$dns_id = "\x80\xc1";$dns_flags = "\x01\x00";$dns_count_queries = "\x00\x01";$dns_count_answers = "\x00\x00";$dns_count_auth_rr = "\x00\x00";$dns_count_add_rr = "\x00\x00";$dns_qry_name = "\x02\x69\x70\x02\x63\x6e\x00";$dns_qry_type = "\x00\x01";$dns_qry_class = "\x00\x01";$dns = $dns_id . $dns_flags . $dns_count_queries . $dns_count_answers . $dns_count_auth_rr . $dns_count_add_rr . $dns_qry_name . $dns_qry_type . $dns_qry_class;//IP头$ip_version = "\x45"; //4位版本$ip_hdr_len = ""; // 4位首部长度$ip_dsfield = "\x00"; //8位服务类型$ip_len = pack('n*',28 + strlen($dns)); //16位总长度$ip_id = "\x55\xf0"; //16位标识$ip_flags = "\x00"; //3位标识$ip_frag_offset = "\x00"; // 13位偏移$ip_ttl = "\x80"; //8位生存时间$ip_proto = "\x11"; //8位协议$ip_src = ipto16("192.168.1.100"); //32位源IP$ip_dst = ipto16("8.8.4.4"); //32位目的IP$ip_checksum = ipchecksum($ip_version,$ip_hdr_len,$ip_dsfield,$ip_len,$ip_id,$ip_flags,$ip_frag_offset,$ip_ttl,$ip_proto,$ip_src,$ip_dst); //16位首部效验和$ip_header = $ip_version . $ip_hdr_len . $ip_dsfield . $ip_len . $ip_id . $ip_flags . $ip_frag_offset . $ip_ttl . $ip_proto . $ip_checksum . $ip_src . $ip_dst;//UDP头$udp_srcport = "\xfc\x39"; //16位源端口$udp_dstport = "\x00\x35"; //16位目的端口$udp_length = pack('n*',8 + strlen($dns)); //16位UDP长度$udp_checksum = udpchecksum($ip_src,$ip_dst,$ip_proto,$udp_length,$udp_srcport,$udp_dstport,$dns); //16位UDP效验和$udp = $udp_srcport . $udp_dstport . $udp_length . $udp_checksum;//$buf = $ip_header . $udp . $dns;$buf = $udp . $dns;function send($host,$port,$buf,$dns_flags){//    $socket = socket_create(AF_INET, SOCK_PACKET, getprotobyname("ip"));    $socket = socket_create(AF_INET, SOCK_RAM,1);    $timeout = array('sec'=>1,'usec'=>500000);//    socket_set_option($socket,IPPROTO_IP,IP_HDRINCL,SO_RCVTIMEO,$timeout);    socket_set_option($socket,SOL_SOCKET,SO_RCVTIMEO,$timeout);//    while(1)        socket_sendto($socket, $buf, strlen($buf), 0, $host, $port);}function udpchecksum($ip_src,$ip_dst,$ip_proto,$udp_length,$udp_srcport,$udp_dstport,$dns){    $data = $ip_src . $ip_dst . "\x00" . $ip_proto . $udp_length . $udp_srcport . $udp_dstport . $udp_length . "\x00\x00" . $dns;    if (strlen($data)%2)    $data .= "\x00";    $bit = unpack('n*', $data);    $sum = array_sum($bit);    while ($sum >> 16)        $sum = ($sum >> 16) + ($sum & 0xffff);    return pack('n*', ~$sum);}function ipchecksum($ip_version,$ip_hdr_len,$ip_dsfield,$ip_len,$ip_id,$ip_flags,$ip_frag_offset,$ip_ttl,$ip_proto,$ip_src,$ip_dst){    $data = $ip_version . $ip_hdr_len . $ip_dsfield . $ip_len . $ip_id . $ip_flags . $ip_frag_offset . $ip_ttl . $ip_proto . "\x00\x00" . $ip_src . $ip_dst;    $bit = unpack('n*', $data);    $sum = array_sum($bit);    while ($sum >> 16)        $sum = ($sum >> 16) + ($sum & 0xffff);    return pack('n*', ~$sum);}function ipto16($ip){    $tmp = explode(".",$ip);    $ip = "";    foreach($tmp as $a => $b)    {        $tmp = dechex($b);        if (strlen($tmp)==1)            $tmp = "0" . $tmp;        $ip .= $tmp;    }    $ip = pack("h*",$ip);    return $ip;}send("8.8.4.4",53,$buf,$dns_flags);

这是个查询向指定dns服务器查询指定域名IP信息的程序，用Wireshark抓包测试可用，但是现在没有用自己的网络层，也就是IP头，我要用自己构造的IP头，
把
$buf = $ip_header . $udp . $dns;
//$buf = $udp . $dns;
改成
$buf = $ip_header . $udp . $dns;
//$buf = $udp . $dns;
结果还是不行，应该是send那函数的问题，请问下应该怎么修改

------解决方案--------------------
不知道你在干什么？利用 sock 包的肯定是在用户层了
封装 ip 应该在下一层