Monitor and switch multiple clients connections in c - c

Question

I am implementing a Linux C program for client/server. I am using select() to connect with multiple clients. The 1st client connected successfully, but 2nd, 3rd and so on, have not give response any response in terminal(server), although client program is executed. The server is connected with some custom shell that run on client side.My server code is:
/**Handle multiple socket connections with select and fd_set on Linux*/
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <errno.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <sys/time.h>
#include <pthread.h>
#define TRUE 1
#define FALSE 0
#define PORT 80
#define BUFSIZE 1025
void *sending( void *fdc)
//void sending(int fd_client)
{
int fd_client= *((int *)fdc);
char buffer[BUFSIZE];
while(1)
{
memset(buffer,0,sizeof(buffer));
fgets(buffer,512,stdin);
if((write(fd_client,buffer,strlen(buffer)))==0)
{
printf("HOST [%d] DISCONNECTED \n",fd_client);
close(fd_client);
}
if((!strcmp(buffer,"quit")) || (!strcmp(buffer,"q")) || (!strcmp(buffer,"QUIT")) || (!strcmp(buffer,"Q")))
{
exit(1);
}
}
}
void *receiving( void *arg)
//void receiving(int fd_client)
{
int fd_client= *((int *)arg);
char buffer[BUFSIZE];
ssize_t size;
while(1)
{
do{
if((size=read(fd_client,buffer,BUFSIZE))==0)
{
printf("HOST [%d] DISCONNECTED \n",fd_client);
close(fd_client);
}
if((write(1,buffer,size))==-1)
{
printf("Eror in Writting to client\n");
perror("");
exit(0);
}
}while(size==BUFSIZE);
}
}
//void *socket_thread(void *arg)
void socket_thread(int fd_client)
{
pthread_t th1,th2;
pthread_create(&th1,NULL,&sending,&fd_client);
pthread_create(&th2,NULL,&receiving,&fd_client);
pthread_join(th1,NULL);
pthread_cancel(th2);
}
int main(int argc , char *argv[])
{
int opt = TRUE;
int master_socket , addrlen , new_socket , client_socket[30] , max_clients = 30 , activity, i , valread , sd;
int max_sd;
struct sockaddr_in address;
char buffer[1025]; //data buffer of 1K
//set of socket descriptors
fd_set readfds;
//a message
char *message = "ECHO Daemon v1.0 \r\n";
//initialise all client_socket[] to 0 so not checked
for (i = 0; i < max_clients; i++)
{
client_socket[i] = 0;
}
//create a master socket
if( (master_socket = socket(AF_INET , SOCK_STREAM , 0)) == 0)
{
perror("socket failed");
exit(EXIT_FAILURE);
}
//set master socket to allow multiple connections , this is just a good habit, it will work without this
if( setsockopt(master_socket, SOL_SOCKET, SO_REUSEADDR, (char *)&opt, sizeof(opt)) < 0 )
{
perror("setsockopt");
exit(EXIT_FAILURE);
}
//type of socket created
address.sin_family = AF_INET;
address.sin_addr.s_addr = INADDR_ANY;
address.sin_port = htons( PORT );
//bind the socket to localhost port 8888
if (bind(master_socket, (struct sockaddr *)&address, sizeof(address))<0)
{
perror("bind failed");
exit(EXIT_FAILURE);
}
printf("Listener on port %d \n", PORT);
//try to specify maximum of 3 pending connections for the master socket
if (listen(master_socket, 3) < 0)
{
perror("listen");
exit(EXIT_FAILURE);
}
//accept the incoming connection
addrlen = sizeof(address);
puts("Waiting for connections ...");
pthread_t tid[30];
while(TRUE)
{
//clear the socket set
FD_ZERO(&readfds);
//add master socket to set
FD_SET(master_socket, &readfds);
max_sd = master_socket;
//add child sockets to set
for ( i = 0 ; i < max_clients ; i++)
{
//socket descriptor
sd = client_socket[i];
//if valid socket descriptor then add to read list
if(sd > 0)
FD_SET( sd , &readfds);
//highest file descriptor number, need it for the select function
if(sd > max_sd)
max_sd = sd;
}
//wait for an activity on one of the sockets , timeout is NULL , so wait indefinitely
activity = select( max_sd + 1 , &readfds , NULL , NULL , NULL);
if ((activity < 0) && (errno!=EINTR))
{
printf("select error");
}
//If something happened on the master socket , then its an incoming connection
if (FD_ISSET(master_socket, &readfds))
{
if ((new_socket = accept(master_socket, (struct sockaddr *)&address, (socklen_t*)&addrlen))<0)
{
perror("accept");
exit(EXIT_FAILURE);
}
//inform user of socket number - used in send and receive commands
printf("New connection , socket fd is %d , ip is : %s , port : %d \n" , new_socket , inet_ntoa(address.sin_addr) , ntohs(address.sin_port));
puts("Welcome message sent successfully");
for (i = 0; i < max_clients; i++)
{
//if position is empty
if( client_socket[i] == 0 )
{
client_socket[i] = new_socket;
printf("Adding to list of sockets as %d\n" , i);
break;
}
}
}
//else its some IO operation on some other socket :)
for (i = 0; i < max_clients; i++)
{
sd = client_socket[i];
if (FD_ISSET( sd , &readfds))
{
socket_thread(sd);
}
}
}
return 0;
}
The program work perfectly for one client but not for multiple. I also tries multi-threads for each file descriptor instead of using select(), but in this case the 2nd client connection overtake the first one in terminal. I want the following outcomes:
Switch between multiple connected clients from Linux terminal(i,e by pressing some keys from keyboard).
When new client is connected in-between, , it prompt a signal , and also can be switch to further read and write operations.
Any help regrading this will be appreciated.