Question

Task 4 [10 pts] Broadcasting Messages to All Clients (Shared Variable Among Threads)

Modify the server code so that when the server sends a message, that message is sent to all connected clients

#include<stdio.h>
#include<string.h>    //strlen
#include<stdlib.h>    //strlen
#include<sys/socket.h>
#include<arpa/inet.h> //inet_addr
#include<unistd.h>    //write
#include<pthread.h> //for threading , link with lpthread
#define MAX 80

#define PORT 6543
#define SA struct sockaddr
// Function designed for chat between client and server.
void join(  pthread_t *thread_id)
{
if(!pthread_join( *thread_id , NULL))
printf("thread %ld complted\n",*thread_id);
pthread_exit(0);//to exit the current thread

}

void func(int *sockfd)
{
char buff[MAX];
int n;
// infinite loop for chat
for (;;) {
    bzero(buff, MAX);
    // read the message from client and copy it in buffer
    read(*sockfd, buff, sizeof(buff));
    // print buffer which contains the client contents
    printf("From client: %s\t To client : ", buff);
    bzero(buff, MAX);
    n = 0;
    // copy server message in the buffer
    while ((buff[n++] = getchar()) != '\n');
    // and send that buffer to client
    write(*sockfd, buff, sizeof(buff));
    // if msg contains "Exit" then server exit and chat ended.
    if (strncmp("exit", buff, 4) == 0) {
        printf("Server Exit...\n");
        break;
    }

   }
   }

       // Driver function

      int main()
     {
int sockfd, connfd, len;
struct sockaddr_in servaddr, cli;
pthread_t thread_id,jointhread_id;
// socket create and verification
sockfd = socket(AF_INET, SOCK_STREAM, 0);
if (sockfd == -1) {
    printf("socket creation failed...\n");
    exit(0);
}
else
    printf("Socket successfully created..\n");
bzero(&servaddr, sizeof(servaddr));
// assign IP, PORT
servaddr.sin_family = AF_INET;
servaddr.sin_addr.s_addr = INADDR_ANY;
servaddr.sin_port = htons(PORT);
// Binding newly created socket to given IP and verification
if ((bind(sockfd, (SA*)&servaddr, sizeof(servaddr))) != 0) {
    printf("socket bind failed...\n");
    exit(0);
}
else
    printf("Socket successfully binded..\n");
// Now server is ready to listen and verification
if ((listen(sockfd, 5)) != 0) {
    printf("Listen failed...\n");
    exit(0);
}
else
    printf("Server listening..\n");
len = sizeof(cli);
// Accept the data packet from client and verification
while(connfd = accept(sockfd, (SA*)&cli, &len))
{
if (connfd < 0) {
    printf("server acccept failed...\n");
    exit(0);
}
else
    printf("server acccept the client..%d.\n",connfd);
if( pthread_create( &thread_id , NULL ,  func , (void*) &connfd) < 0)
    {
        perror("could not create thread");
        return 1;
    }
    
if( pthread_create( &jointhread_id , NULL ,  join , (void*) &thread_id) < 0)
    {
        perror("could not create thread");
        return 1;
    }
   
}

// After chatting close the socket
close(sockfd);

}

Answer 1

#include <stdio.h>
#include <netdb.h>
#include <netinet/in.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/types.h>
#define MAX 80
#define PORT 8080
#define SA struct sockaddr
  
// Function designed for chat between client and server.
void func(int sockfd)
{
char buff[MAX];
int n;
// infinite loop for chat
for (;;) {
bzero(buff, MAX);
  
// read the message from client and copy it in buffer
read(sockfd, buff, sizeof(buff));
// print buffer which contains the client contents
printf("From client: %s\t To client : ", buff);
bzero(buff, MAX);
n = 0;
// copy server message in the buffer
while ((buff[n++] = getchar()) != '\n')
;
  
// and send that buffer to client
write(sockfd, buff, sizeof(buff));
  
// if msg contains "Exit" then server exit and chat ended.
if (strncmp("exit", buff, 4) == 0) {
printf("Server Exit...\n");
break;
}
}
}
  
// Driver function
int main()
{
int sockfd, connfd, len;
struct sockaddr_in servaddr, cli;
  
// socket create and verification
sockfd = socket(AF_INET, SOCK_STREAM, 0);
if (sockfd == -1) {
printf("socket creation failed...\n");
exit(0);
}
else
printf("Socket successfully created..\n");
bzero(&servaddr, sizeof(servaddr));
  
// assign IP, PORT
servaddr.sin_family = AF_INET;
servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
servaddr.sin_port = htons(PORT);
  
// Binding newly created socket to given IP and verification
if ((bind(sockfd, (SA*)&servaddr, sizeof(servaddr))) != 0) {
printf("socket bind failed...\n");
exit(0);
}
else
printf("Socket successfully binded..\n");
  
// Now server is ready to listen and verification
if ((listen(sockfd, 5)) != 0) {
printf("Listen failed...\n");
exit(0);
}
else
printf("Server listening..\n");
len = sizeof(cli);
  
// Accept the data packet from client and verification
connfd = accept(sockfd, (SA*)&cli, &len);
if (connfd < 0) {
printf("server acccept failed...\n");
exit(0);
}
else
printf("server acccept the client...\n");
  
// Function for chatting between client and server
func(connfd);
  
// After chatting close the socket
close(sockfd);
}

• using create(), Create TCP socket.
• using bind(), Bind the socket to server address.
• using listen(), put the server socket in a passive mode, where it waits for the client to approach the server to make a connection
• using accept(), At this point, connection is established between client and server, and they are ready to transfer data.
• Go back to Step 3.