#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
  
#define PORT 4950
#define BUFSIZE 1024

void send_to_all(int j, int i, int sockfd, int nbytes_recvd, char *recv_buf, fd_set *master)
{
   if (FD_ISSET(j, master)){
       if (j != sockfd && j != i) {
           if (send(j, recv_buf, nbytes_recvd, 0) == -1) {
               perror("send");
           }
       }
   }
}
      
void send_recv(int i, fd_set *master, int sockfd, int fdmax)
{
   int nbytes_recvd, j;
   char recv_buf[BUFSIZE], buf[BUFSIZE];
  
   if ((nbytes_recvd = recv(i, recv_buf, BUFSIZE, 0)) <= 0) {
       if (nbytes_recvd == 0) {
           printf("socket %d hung up\n", i);
       }else {
           perror("recv");
       }
       close(i);
       FD_CLR(i, master);
   }else {
   //   printf("%s\n", recv_buf);
       for(j = 0; j <= fdmax; j++){
           send_to_all(j, i, sockfd, nbytes_recvd, recv_buf, master );
       }
   }  
}
      
void connection_accept(fd_set *master, int *fdmax, int sockfd, struct sockaddr_in *client_addr)
{
   socklen_t addrlen;
   int newsockfd;
  
   addrlen = sizeof(struct sockaddr_in);
   if((newsockfd = accept(sockfd, (struct sockaddr *)client_addr, &addrlen)) == -1) {
       perror("accept");
       exit(1);
   }else {
       FD_SET(newsockfd, master);
       if(newsockfd > *fdmax){
           *fdmax = newsockfd;
       }
       printf("new connection from %s on port %d \n",inet_ntoa(client_addr->sin_addr), ntohs(client_addr->sin_port));
   }
}
  
void connect_request(int *sockfd, struct sockaddr_in *my_addr)
{
   int yes = 1;
      
   if ((*sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
       perror("Socket");
       exit(1);
   }
      
   my_addr->sin_family = AF_INET;
   my_addr->sin_port = htons(4950);
   my_addr->sin_addr.s_addr = INADDR_ANY;
   memset(my_addr->sin_zero, '', sizeof my_addr->sin_zero);
      
   if (setsockopt(*sockfd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(int)) == -1) {
       perror("setsockopt");
       exit(1);
   }
      
   if (bind(*sockfd, (struct sockaddr *)my_addr, sizeof(struct sockaddr)) == -1) {
       perror("Unable to bind");
       exit(1);
   }
   if (listen(*sockfd, 10) == -1) {
       perror("listen");
       exit(1);
   }
   printf("\nTCPServer Waiting for client on port 4950\n");
   fflush(stdout);
}
int main()
{
   fd_set master;
   fd_set read_fds;
   int fdmax, i;
   int sockfd= 0;
   struct sockaddr_in my_addr, client_addr;
  
   FD_ZERO(&master);
   FD_ZERO(&read_fds);
   connect_request(&sockfd, &my_addr);
   FD_SET(sockfd, &master);
  
   fdmax = sockfd;
   while(1){
       read_fds = master;
       if(select(fdmax+1, &read_fds, NULL, NULL, NULL) == -1){
           perror("select");
           exit(4);
       }
      
       for (i = 0; i <= fdmax; i++){
           if (FD_ISSET(i, &read_fds)){
               if (i == sockfd)
                   connection_accept(&master, &fdmax, sockfd, &client_addr);
               else
                   send_recv(i, &master, sockfd, fdmax);
           }
       }
   }
   return 0;
}