socket

#include <errno.h>
#include <unistd.h>
#include <netdb.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <stdio.h>
#include <stdlib.h>
#include <netinet/ip_icmp.h>
#include <arpa/inet.h>
#include <string.h>

char msg[300];

int main()
{

  char adr[] = "127.0.0.1";

  int fd=socket(PF_INET,SOCK_DGRAM,IPPROTO_ICMP);
  if (fd==-1) {
    return -1;
  }

  const size_t req_size=8;
  struct icmphdr req;
  req.type=8;
  req.code=0;
  req.checksum=0;
  req.un.echo.id=htons(12);
  req.un.echo.sequence=htons(1);

  struct sockaddr_in sin;
  sin.sin_family = AF_INET;
  sin.sin_addr.s_addr = inet_addr (adr);

  if (sendto(fd,&req,req_size,0,
    (struct sockaddr *) &sin,sizeof(sin))==-1) {
    return -1;
  }


  int  n = recv(fd, msg, sizeof(msg), 0);
  if(n <= 0) {
    printf("recv fail\n");
    return -1;
  }


  struct icmphdr rcv_hdr;
  memcpy(&rcv_hdr, msg, sizeof rcv_hdr);
  if (rcv_hdr.type == ICMP_ECHOREPLY) {
    printf("ICMP Reply, id=0x%x, sequence =  0x%x\n",
        rcv_hdr.un.echo.id, rcv_hdr.un.echo.sequence);
  } else {
    printf("Got ICMP packet with type 0x%x ?!?\n", rcv_hdr.type);
  }

  return 0;
}