TCP协议学习记录 (一) ICMP时间戳请求

程序只实现了获取时间戳,至于将时间戳转换成具体日期和时间,暂时没有好的办法。

 #define  TIME_STAMP_REQUEST 13

 struct iphdr
 {
     unsigned char  ip_hdr_len : ; //包头长度
     unsigned char  ip_version : ; //版本
     unsigned char  ip_tos;

     unsigned short ip_length;  //总长度
     unsigned short ip_identify;//标识
     unsigned short ip_offset;//片偏移
     unsigned char  ip_ttl;
     unsigned char  ip_protocol;
     unsigned short ip_cksum;

     struct in_addr ip_src; //源地址
     struct in_addr ip_dst; //目的地址
 };

 struct icmphdr
 {
     unsigned char  icmp_type; //8位类型
     unsigned char  icmp_code; //8位代码
     unsigned short icmp_cksum; //16位的校验和

     unsigned short icmp_identify;
     unsigned short icmp_seq;

     unsigned int   icmp_otime;
     unsigned int   icmp_rtime; //接收时间
     unsigned int   icmp_ttime; //应答时间
 };

 unsigned short checksum(int count,unsigned short* addr)
 {
     long sum = ;

     while(count > )
     {
         sum   +=*addr++;
         count -= sizeof(unsigned short);
     }

     if(count > )
     {
         sum  +=*(unsigned char*)addr;
     }

     while(sum >> )
     {
         sum = (sum & 0xFFFF) + (sum >> );
     }

     return (unsigned short)(~sum);
 }

 bool timestamp_request(char * argv)
 {
     WSADATA wsaData;
     WSAStartup(MAKEWORD(, ), &wsaData);

     SOCKET soc = socket(AF_INET,SOCK_RAW,IPPROTO_ICMP);
     if(soc == -)
     {
     　　printf("create raw socket failed!\n");
     　　return false;
     }

     struct sockaddr_in  addrsrv;

     addrsrv.sin_family      = AF_INET;
     addrsrv.sin_port        = htons();
     addrsrv.sin_addr.s_addr = inet_addr("202.112.10.36"); //预设地址

     struct hostent* phostent  = gethostbyname(argv);
     if (phostent)
     {
     　　addrsrv.sin_addr.s_addr = *(u_long *)phostent->h_addr_list[];;
     }

     printf("sending timestamp request to host [%s]\n",inet_ntoa(addrsrv.sin_addr));

     icmphdr ihdr       = {};

     ihdr.icmp_type     = TIME_STAMP_REQUEST;
     ihdr.icmp_identify = (unsigned short)GetCurrentProcessId();
     ihdr.icmp_cksum    = checksum(sizeof(icmphdr),(unsigned short *)&ihdr);

     if(sendto(soc,(char *)&ihdr,sizeof(ihdr),,(sockaddr *)&addrsrv,sizeof(addrsrv)) == -)
     {
     　　printf("send icmp packet failed!\n");
     　　return false;
     }

     struct sockaddr_in addrcli;

     int  nlength       = sizeof(addrcli);
     char recv[MAXBYTE] = {};

     struct timeval timeout;
     timeout.tv_sec  = ;
     timeout.tv_usec = ;
     setsockopt(soc, SOL_SOCKET,SO_RCVTIMEO, (char*)&timeout,sizeof(timeout));

     if(recvfrom(soc,recv,MAXBYTE,,(sockaddr *)&addrcli,&nlength) == -)
     {
     　　printf("recv ip packet failed!\n");
     　　return false;
     }

     iphdr* piphdr = (iphdr *)recv;
     if(checksum(piphdr->ip_hdr_len << 2,(unsigned short *)piphdr) != )
     {
     　　printf("invalid ip packet!\n");
     　　return false;
     }

     icmphdr* pichdr = (icmphdr *)(piphdr + );
     if(checksum(sizeof(icmphdr),(unsigned short *)pichdr) != )
     {
         printf("invalid icmp packet!\n");
         return false;
     }

     printf("recv time:[%u] transmit time:[%u]\n",ntohl(pichdr->icmp_rtime),ntohl(pichdr->icmp_ttime));

     return true;
 }

 int main(int argc,char * argv[])
 {
     if(argc < )
     {
     　　return ;
     }

     timestamp_request(argv[]);
 }