client.c

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

typedef struct {
    int id_number;
    int age;
    float salary;
} employee;

// how to send and receive structs
void send_and_get_employee(int socket, employee *e)  
{
    size_t payload_length = sizeof(employee);

    // send the original struct
    writen(socket, (unsigned char *) &payload_length, sizeof(size_t));	
    writen(socket, (unsigned char *) e, payload_length);	 		

    // get back the altered struct
    readn(socket, (unsigned char *) &payload_length, sizeof(size_t));	   
    readn(socket, (unsigned char *) e, payload_length);

    // print out details of received & altered struct
    printf("Age is %d\n", e->age);
    printf("id is %d\n", e->id_number);
    printf("Salary is %6.2f\n", e->salary);    
} // end send_and_get_employee()

// how to receive a string
void get_hello(int socket)
{
    char hello_string[32];
    size_t k;

    readn(socket, (unsigned char *) &k, sizeof(size_t));	
    readn(socket, (unsigned char *) hello_string, k);

    printf("Hello String: %s\n", hello_string);
    printf("Received: %zu bytes\n\n", k);
} // end get_hello()

int main(void)
{
    // *** this code down to the next "// ***" does not need to be changed except the port number
    int sockfd = 0;

    struct sockaddr_in serv_addr;

	//socket creation to also return an erro message on fail
    if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
	perror("Error - could not create socket");
	exit(EXIT_FAILURE);
    }


    // Server information. 
    serv_addr.sin_family = AF_INET;// ip type
    serv_addr.sin_port = htons(50001);//port 
    serv_addr.sin_addr.s_addr = inet_addr("127.0.0.1");//ip address


    // try to connect...
    if (connect(sockfd, (struct sockaddr *) &serv_addr, sizeof(serv_addr)) == -1)  {
	perror("Error - connect failed");
	exit(1);
    } else
       printf("Connected to server...\n");

    // ***
    // your own application code will go here and replace what is below... 
    // i.e. your menu etc.

	
	
	char input[5];

	do{
		printf("                              System C by Sisekelo\n                          \n================================================================================");

  printf(" \n\nPress A: Your creator's details \nPress B: Random Number \nPress C: for UNAME \nPress D: for Files \nPress Z: to terminate program \n \n");
  
		fgets(input, 5, stdin);

		
		size_t n = strlen(input) + 1;
		writen(sockfd, (unsigned char *) &n, sizeof(size_t));	
		writen(sockfd, (unsigned char *) input, n);	  

		printf("good option %s\n", input);
		char valread[32]; 
		size_t k;

		//TO DO: ensure that only a b c are clicked

		readn(sockfd, (unsigned char *) &k, sizeof(size_t));	
		readn(sockfd, (unsigned char *) valread, k);

		printf("%s\n", valread);
		printf("\n")

	}
	while(input[0] != 'q');

	
	//get_hello(sockfd);


    // get a string from the server
    //get_hello(sockfd);

    // send and receive a changed struct to/from the server
    //employee *employee1;		
   // employee1 = (employee *) malloc(sizeof(employee));

    // arbitrary values
    //employee1->age = 23;
    //employee1->id_number = 3;
    //employee1->salary = 13000.21;

    //int i;
    //for (i = 0; i < 5; i++) {
         //printf("(Counter: %d)\n", i);
	 //send_and_get_employee(sockfd, employee1);
         //printf("\n");
    //}

    //free(employee1);

    // *** make sure sockets are cleaned up

    close(sockfd);

    exit(EXIT_SUCCESS);
} // end main()

server.c

#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <pthread.h>
#include "rdwrn.h"

// thread function
void *client_handler(void *);

//send Hello
void send_hello(int);

//send Random
void send_rando(int);


// you shouldn't need to change main() in the server except the port number
int main(void)
{
    int listenSocket = 0, connfd = 0;

    //server structure 
    struct sockaddr_in serv_addr;

    //client structure
    struct sockaddr_in client_addr;

    //memory reserved for soket
    socklen_t socksize = sizeof(struct sockaddr_in);
    
    //socket creation
    listenSocket = socket(AF_INET, SOCK_STREAM, 0);

    // set asside memory for server structure  
    memset(&serv_addr, '0', sizeof(serv_addr));

    //instatiate server structure 
    serv_addr.sin_family = AF_INET; //Address type IPV4
    serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);//IP address
    serv_addr.sin_port = htons(50001);//port number 

    //bind new socket to the structure 
    bind(listenSocket, (struct sockaddr *) &serv_addr, sizeof(serv_addr));

    if (listen(listenSocket, 10) == -1) {
	perror("Failed to listen");
	exit(EXIT_FAILURE);
    }
    // end socket setup

	printf("Waiting for a client to connect...\n");

	connfd = accept(listenSocket, (struct sockaddr *) &client_addr, &socksize);
	printf("Connection accepted...\n");

    	//Accept and incoming connection
    	puts("Waiting for incoming connections...");


    	while (1) {

	pthread_t sniffer_thread;
        // third parameter is a pointer to the thread function, fourth is its actual parameter
	if (pthread_create(&sniffer_thread, NULL, client_handler, (void *) &connfd) < 0) {
	    perror("could not create thread");
	    exit(EXIT_FAILURE);
	}
	//Now join the thread , so that we dont terminate before the thread
	pthread_join( sniffer_thread , NULL);
	printf("Handler assigned\n");
    }

    // never reached...
    // ** should include a signal handler to clean up
    exit(EXIT_SUCCESS);
} // end main()




// thread function - one instance of each for each connected client
// this is where the do-while loop will go
void *client_handler(void *socket_desc)
{
    //Get the socket descriptor
    int connfd = *(int *) socket_desc;
	
	char buffer[5];

	do{
		size_t k;

		readn(connfd, (unsigned char *) &k, sizeof(size_t));	
		readn(connfd, (unsigned char *) buffer, k);
    	 	printf(" the input that the client entered is %s\n",buffer );
	
     		switch(buffer[0])
     		{
         	case 'a':
					case 'A':
	   					send_hello(connfd);
           		printf("Your option is: %s", buffer);
	   					break;
					case 'b':
         	case 'B':
							send_rando(connfd);
           		printf("Your option is: %s", buffer);
	   					break;
         	case 'c':
           		printf("Your option is: %s", buffer);
	   					break;
        	default:
					 		write(connfd, buffer, sizeof(buffer));
					 		printf("Message sent\n");
						  printf("Default: Value is: %s\n", buffer);
	   					break;
    		}

		}
		while( buffer[0]!= 'q' );

    shutdown(connfd, SHUT_RDWR);
    close(connfd);

    printf("Thread %lu exiting\n", (unsigned long) pthread_self());

    // always clean up sockets gracefully
    shutdown(connfd, SHUT_RDWR);
    close(connfd);

    return 0;
}  // end client_handler()




// how to send a string
void send_hello(int socket)
{
    char hello_string[] = "Sisekelo Dlamini | S1719039 | 127.0.0.1";

    size_t n = strlen(hello_string) + 1;
    writen(socket, (unsigned char *) &n, sizeof(size_t));	
    writen(socket, (unsigned char *) hello_string, n);	  
} // end send_hello()

// how to send a string 2
void send_rando(int socket)
{

		srand(time(NULL));
		int c, d;

		char integer_string[32]; //prepares to be an integer
		char other_string[64] = "Your lucky numbers are:  "; // create new string for words
		char empty_string[12] = "  "; //empty string

		for (c = 0; c <= 4; c++) {
		  d = rand() % 100 + 1; // random integer
			int integer = d; //get integer
			sprintf(integer_string, "%d", integer);//convert integer to string
			strcat(other_string, integer_string); // Add integer to new string
			strcat(other_string, empty_string); // Add space
		};
		
		
    size_t n = strlen(other_string) + 1;
    writen(socket, (unsigned char *) &n, sizeof(size_t));	
    writen(socket, (unsigned char *) other_string, n);	  
} // end send_rando()