#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <string.h>
#include <sys/time.h>
#include <unistd.h>




#define BYTES_NR  64
#define  MSG_NR    512


char  buf[BYTES_NR];
char  buf2[BYTES_NR];

char  msg[MSG_NR][BYTES_NR];
char  answ[MSG_NR][BYTES_NR];

struct timeval xstime[MSG_NR];
struct timeval xftime[MSG_NR];



int main(int argc,char** argv)
{
  int i,sock,rval;
  socklen_t length;
  unsigned long delay;
  struct sockaddr_in server,client;
  struct hostent *hp, *gethostbyname();

  if(argc !=3)
  {
    fprintf(stderr,"Usage: %s servername serverport\n",argv[0]);
    exit(-1);
  }

  for(i=0;i<MSG_NR;i++)
  {
    sprintf(&msg[i][0],"%d",i);
  }

  /* Create socket */
  sock = socket(AF_INET,SOCK_DGRAM,0);
  if(sock<0)
  {
    perror("opening stream socket");
    exit(1);
  }

  client.sin_family = AF_INET;
  client.sin_addr.s_addr = INADDR_ANY;
  client.sin_port = htons(0);
 
  if (bind(sock,(struct sockaddr *)&client,sizeof client) <0)
  {
    perror("sending datagram message");
    exit(1);
  }
  length = sizeof(client);
  if(getsockname(sock,(struct sockaddr *)&server,&length)<0)
  {
    perror("getting socket name");
    exit(1);
  }
  printf("Socket port #%d\n",ntohs(client.sin_port));

  hp = gethostbyname(argv[1]);
  if (hp == 0)
  {
    fprintf(stderr,"%s :unknow host",argv[1]);
    exit(2);
  }

  bcopy( (char *)hp ->h_addr, (char *)&server.sin_addr,hp ->h_length);
  server.sin_family = AF_INET;
  server.sin_port = htons(atoi(argv[2]));

  for(i=0;i<MSG_NR;i++)
  {
    strcpy(buf,msg[i]);
    gettimeofday(&xstime[i],NULL);

    if (sendto(sock,buf,sizeof buf,0,(struct sockaddr *)&server,sizeof server)<0)
      perror("sendto problem");

    if((rval = read(sock,buf2,sizeof buf2))<0)
      perror("reading stream message");

    strcpy(answ[i],buf2);
    gettimeofday(&xftime[i],NULL);
  }
  close(sock);

  for(i=0;i<MSG_NR;i++)
  {
    delay= (xftime[i].tv_sec-xstime[i].tv_sec)*1000000.+(xftime[i].tv_usec-xstime[i].tv_usec);
    printf("msg %d [%s]: %0.3f ms\n",i,answ[i],delay/1000.);
  }

  return 0;
}