#include //校验和计算

unsigned short calc_cksum(char *buff,int len)

{

int blen = len;

unsigned short *mid = (unsigned short*)buff;

unsigned short te = 0;

unsigned int sum = 0;

while(blen > 1)

{

sum += *mid++;

blen -= 2;

}

if(blen == 1)

{

te = *(unsigned char*)mid;

te = (te << 8) & 0xff;

sum += te;

}

sum = (sum >> 16) + (sum&0xffff);

sum += sum >>16;

return (unsigned short)(~sum);

}

static void time_packet(char *buff,int len,int id,int seq)

{

time_t *ti;

struct icmp *icmp = (struct icmp*)buff;

struct timeval val;

icmp->icmp_type = 13; //Timestamp Request

icmp->icmp_code = 0;

icmp->icmp_cksum = 0; //first set zero

icmp->icmp_id = id & 0xffff;

icmp->icmp_seq = seq;

gettimeofday(&val,NULL);

//24*60*60 = 86400 自午夜开始计算的毫秒数

icmp->icmp_otime = htonl((val.tv_sec % 86400)*1000 + val.tv_usec / 1000);

icmp->icmp_rtime = 0;

icmp->icmp_ttime = 0;

//计算校验和

icmp->icmp_cksum = calc_cksum(buff,len);

return;

}

void parse_packet(char *buff,int len)

{

struct icmp *icmp;

struct iphdr *iphead = (struct iphdr *)buff;

struct in_addr addr;

addr.s_addr = iphead->saddr;

printf("comefrom ip=%s ",inet_ntoa(addr));

//跳过ip头

icmp = (struct icmp *)(buff+sizeof(struct iphdr));

//看传输回的包校验和是否正确

if(calc_cksum((char *)icmp,len-sizeof(sizeof(struct iphdr))) > 1)

{

printf("receiver error\n");

return;

}

printf("type=%d seq=%d id=%d pid=%d otime=%d rtime=%d ttime=%d\n",icmp->icmp_type,icmp->icmp_seq,icmp->icmp_id,(getpid()&0xffff),ntohl(icmp->icmp_otime),ntohl(icmp->icmp_rtime),ntohl(icmp->icmp_ttime));

}

int main(int argc,char *argv[])

{

int skfd;

struct sockaddr_in addr={0};

struct sockaddr_in saddr={0};

char buff[64]={0};

char recvbuff[512]={0};

int ret;

int addrlen = 0;

int count = 5;

int i = 1;

skfd = socket(PF_INET,SOCK_RAW,IPPROTO_ICMP);

if(skfd < 0)

{

printf("socket error\n");

return -1;

}

addr.sin_family = AF_INET;

addr.sin_addr.s_addr = inet_addr("192.168.21.244");

//每一秒发送一次 共发送count次

while(count > 0)

{

//序列号seq 从1 开始传输 buff的大小为64

memset(buff,0,sizeof(buff));

time_packet(buff,64,getpid(),i);

i++;

count --;

//将数据发送出去

ret = sendto(skfd,buff,64,0,(struct sockaddr *)&addr,sizeof(addr));

if(ret <= 0)

{

printf("send error\n");

goto out;

}

else

printf("send success ret=%d\n",ret);

//接收echo replay

memset(recvbuff,0,sizeof(recvbuff));

memset(&saddr,0,sizeof(saddr));

addrlen = sizeof(saddr);

ret = recvfrom(skfd,recvbuff,sizeof(recvbuff),0,(struct sockaddr *)&saddr,&addrlen);

if(ret <= 0)

{

printf("recv error\n");

continue;

}

parse_packet(recvbuff,ret);

sleep(2);

}

out:

close(skfd);

return 0;

}