How to count time in socket - c

Question

I have a simple server-client program which acts according to the received data from client.
When the received data is string start I want the server to count time in seconds until it receives stop command from client, and as server receives stop server sends back counted seconds to the client.
I'm new in C programming and I don't know how to use time.h library. I have tried to use some commands, but got few errors.
/* tcpserver.c */
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/sysinfo.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include "address.h"
int main() {
int sock, connected, bytes_recieved , true = 1, number;
char send_data [1024] , recv_data[1024];
struct sockaddr_in server_addr,client_addr;
struct sysinfo info;
int sin_size;
if ((sock = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
perror("Socket");
exit(1);
}
if (setsockopt(sock,SOL_SOCKET,SO_REUSEADDR,&true,sizeof(int)) == -1) {
perror("Setsockopt");
exit(1);
}
server_addr.sin_family = AF_INET;
server_addr.sin_port = htons(1237);
server_addr.sin_addr.s_addr = INADDR_ANY;
bzero(&(server_addr.sin_zero),8);
if (bind(sock, (struct sockaddr *)&server_addr, sizeof(struct sockaddr))
== -1) {
perror("Unable to bind");
exit(1);
}
if (listen(sock, 5) == -1) {
perror("Listen");
exit(1);
}
printf ("\nTCPServer Waiting for client on port 1237");
fflush(stdout);
number = 0;
while(1) {
sin_size = sizeof(struct sockaddr_in);
connected = accept(sock, (struct sockaddr *)&client_addr,&sin_size);
printf("\n I got a connection from (%s , %d)",
inet_ntoa(client_addr.sin_addr),ntohs(client_addr.sin_port));
send(connected, "Hello, this is simple program.", 100, 1);
while (1) {
printf("\n SEND (q or Q to quit) : ");
fgets(send_data, sizeof(send_data), stdin);
bytes_recieved = recv(connected,recv_data,1024,0);
recv_data[bytes_recieved] = '\0';
if (strcmp(favoriteDairyProduct, "start") == 0 || strcmp(favoriteDairyProduct, "START") == 0) {
// count the time until stop is recieved
}
printf("\n RECIEVED DATA = %s " , recv_data);
fflush(stdout);
send(connected, send_data,strlen(send_data), 0);
}
}
close(sock);
return 0;
}
Here is the client code. One other thing I would like to do is to change the program to receive multiple clients. But for now timer is more important.
/* tcpclient.c */
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/sysinfo.h>
#include <netdb.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include "address.h"
#include <time.h>
int main()
{
int sock, bytes_recieved, number;
char send_data[1024],recv_data[1024];
struct hostent *host;
struct sockaddr_in server_addr;
struct sysinfo info;
host = gethostbyname("127.0.0.1");
if ((sock = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
perror("Socket");
exit(1);
}
server_addr.sin_family = AF_INET;
server_addr.sin_port = htons(1237);
server_addr.sin_addr = *((struct in_addr *)host->h_addr);
bzero(&(server_addr.sin_zero),8);
if (connect(sock, (struct sockaddr *)&server_addr, sizeof(struct sockaddr)) == -1) {
perror("Connect");
exit(1);
}
while(1) {
bytes_recieved = recv(sock,recv_data,1024,0);
recv_data[bytes_recieved] = '\0';
printf("\nRecieved data = %s " , recv_data);
printf("\nSEND (q or Q to quit) : ");
fgets(send_data, sizeof(send_data), stdin);
send(sock,send_data, sizeof(send_data), 0);
}
close(sock);
return 0;
}

Answer 1

Depending on the platform you are on, you could use gettimeofday() when you receive both the start and stop messages.
#include <sys/time.h>
struct timeval t1, t2;
if (<received start command>) {
gettimeofday(&t1, NULL);
}
if (<received stop command>) {
gettimeofday(&t2, NULL);
}
Each gives you the current time in seconds and microseconds. You have to find the difference between the two.
time_t diff_sec = t2.tv_sec - t1.tv_sec;
suseconds_t diff_usec = t2.tv_usec - t1.tv_usec;
Of course you have to take into account that t2.tv_usec could be smaller than t1.tv_usec.
You should also verify that you have received a start before a stop, or the results won't make sense.
I'll leave the rest as an exercise to the reader since this looks like homework.