Symmetria

Some notes: Boxes MUST be in the same time zone and MUST be NTP synched

Client.c

#include <arpa/inet.h>
#include <netinet/in.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
#include <sys/timeb.h>

#define SRV_IP "CHANGE_ME"
#define PORT 7890
#define NUM_PACKETS 100
#define PACKET_DELAY 100

void diep(char *stringz)
{
   perror(stringz);
   exit(-1);
}

struct s_timestamp {
        int sequence;
        int tseconds;
        int tmilli;
};

void delay_time(int PACKETDELAY) {
   int t_diff = 0;
   struct timeb t_delay_s, t_delay_e;

   memset(&t_delay_s, sizeof(struct timeb), 0);
   memset(&t_delay_e, sizeof(struct timeb), 0);
   ftime(&t_delay_s);
   while(t_diff < PACKETDELAY) {
     ftime(&t_delay_e);
     t_diff=(1000 * (t_delay_e.time - t_delay_s.time) + (t_delay_e.millitm - t_delay_s.millitm));
   }
}

int main() {
   struct sockaddr_in udp_socket;
   char payload[sizeof(struct timeb)];
   int u_sock, counter, socklen=sizeof(udp_socket);
   struct s_timestamp p_data;
   struct timeb t_current;

   if((u_sock=socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) == -1)
        diep("socket");

   memset((char *)&udp_socket, 0, sizeof(udp_socket));

   udp_socket.sin_family = AF_INET;
   udp_socket.sin_port = htons(PORT);

    if (inet_aton(SRV_IP, &udp_socket.sin_addr)==0) {
       fprintf(stderr, "inet_aton() failed\n");
       exit(1);
   }

   for(counter = 0; counter < NUM_PACKETS; counter++) {
      memset(&p_data, sizeof(struct s_timestamp),0);
      printf("Sending packet %d\n", counter);

      ftime(&t_current);
      p_data.tseconds = t_current.time;
      p_data.tmilli = t_current.millitm;
      p_data.sequence=counter;
      printf("Transmitting packet with sequence number %d\n",p_data.sequence);
      if (sendto(u_sock, (void *)&p_data, sizeof(struct s_timestamp), 0, (struct sockaddr *)&udp_socket, socklen) == -1)
        diep("sendto()");
      delay_time(PACKET_DELAY);
      }
   printf("Size of struct s_timestamp is %d\n",sizeof(struct s_timestamp));
}


Server.C:


#include <arpa/inet.h>
#include <netinet/in.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
#include <sys/timeb.h>

#define PORT 7890
#define NUM_PACKETS 100

void diep(char *stringz)
{
   perror(stringz);
   exit(-1);
}

struct s_timestamp {
        int sequence;
        int tseconds;
        int tmilli;
};

int main() {
   struct sockaddr_in udp_local, udp_socket;
   int u_sock, counter, socklen=sizeof(udp_socket);
   struct s_timestamp p_data;
   struct timeb t_current;
   int delay;

   if((u_sock=socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) == -1)
        diep("socket");

   memset((char *)&udp_socket, 0, sizeof(udp_socket));

   udp_local.sin_family=AF_INET;
   udp_local.sin_port=htons(PORT);
   udp_local.sin_addr.s_addr = htonl(INADDR_ANY);
   if(bind(u_sock, (struct sockaddr *)&udp_local, sizeof(udp_local)) == -1)
       diep("socket");

   while(1) {
   for(counter = 0; counter < NUM_PACKETS; counter++) {
      if(recvfrom(u_sock, (void *)&p_data, sizeof(struct s_timestamp), 0, (struct sockaddr *)&udp_socket, &socklen) == -1)
         diep("recvfrom()");
      printf("Received packet with %d bytes of data with sequence number %d\n",socklen, p_data.sequence);
      printf("Received timestamp %d:%d\n",p_data.tseconds, p_data.tmilli);
      ftime(&t_current);
      delay = (1000 * (t_current.time - p_data.tseconds) + (t_current.millitm - p_data.tmilli));
      printf("Received packet.  Packet delay calculated at %d ms\n", delay);
   }
   }

   close(u_sock);
   return 0;

}