Ignou Solved Assignments

1. Write a TCP client and TCP server program in C language on UNIX operating system. The
client program begins by sending a request, after accepting the client request; server program
sends back a confirmation and its clock time to the client. Client program displays the server
clock time on its screen. The maximum concurrent clients this server can handle are four.
Display necessary messages, wherever necessary.
(20 marks)
Ans:
Header file Explanation 
#include <stdio.h> /* printf() and fprintf() */
#include <sys/types.h /* Socket data types */
#include <sys/socket.h> /* socket(), connect(), send(), recv() */
#include <netinet/in.h> /* IP Socket data types */
#include <arpa/inet.h> /* sockaddr_in, inet_addr() */
#include <stdlib.h> /* atoi() */
#include <string.h> /* memset() */

#include <unistd.h> /* close() */

TCP Client Program 
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

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

#include <unistd.h>
int main(int argc, char *argv[])
{
 printf("This is the client program\n");

 int sockfd;
 int len, rc ;
 struct sockaddr_in address;
 int result;
 char ch = 'A';

 //Create socket for client.
 sockfd = socket(PF_INET, SOCK_STREAM, 0);
 if (sockfd == -1) {
 perror("Socket create failed.\n") ;
 return -1 ;
 }

 //Name the socket as agreed with server.
 address.sin_family = AF_INET;
 address.sin_addr.s_addr = inet_addr("127.0.0.1");
 address.sin_port = htons(7734);
 len = sizeof(address);

 result = connect(sockfd, (struct sockaddr *)&address, len);
 if(result == -1)
 {
 perror("Error has occurred");
 exit(-1);
 }

 while ( ch < 'Y') {

 //Read and write via sockfd
 rc = write(sockfd, &ch, 1);
 printf("write rc = &#37;d\n", rc ) ;
if (rc == -1) break ;

 read(sockfd, &ch, 1);
 printf("Char from server = %c\n", ch);
 //if (ch == 'A') sleep(5) ; // pause 5 seconds
 }
 close(sockfd);

 exit(0);
}

TCP Server Program
#include <config.h>
 #include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>

/// SERVER

int main(int argc, char *argv[])
{ //Declaring process variables.
 int server_sockfd, client_sockfd;
 int server_len ;
 int rc ;
 unsigned client_len;
 struct sockaddr_in server_address;
 struct sockaddr_in client_address;

 //Remove any old socket and create an unnamed socket for the server.
 server_sockfd = socket(AF_INET, SOCK_STREAM, 0);
 server_address.sin_family = AF_INET;
 server_address.sin_addr.s_addr = htons(INADDR_ANY);
 server_address.sin_port = htons(7734) ;