Multiple clients on server with multithreading using Socket Programming in C - c

Question

I want to write some code using multithreading and sockets to create a server and this server can accept four connections (clients)
How can I receive and send data to the client? How do I know from which client I receive my data?
This the code:
if (listen(serverSocket, 20) == 0)
printf("Listening\n");
else
printf("Error\n");
int i = 0;
while (1){
addr_size = sizeof(serverStorage);
//accept
newSocket = accept(serverSocket,
(struct sockaddr*)&serverStorage,
&addr_size);
int type = 0;
recv(newSocket,
&type, sizeof(type), 0);
if (type == 1) {
// Creater readers thread
if (pthread_create(&readerthreads[i++], NULL,
reader, &newSocket)
!= 0)
// Error in creating thread
printf("Failed to create thread\n");
}
else if (type == 2) {
// Create writers thread
if (pthread_create(&writerthreads[i++], NULL,
writer, &newSocket)
!= 0)
// Error in creating thread
printf("Failed to create thread\n");
}
if (i >= 5) {
// Update i
i = 0;
while (i < 5) {
// Suspend execution of
// the calling thread
// until the target
// thread terminates
pthread_join(writerthreads[i++],
NULL);
pthread_join(readerthreads[i++],
NULL);
}
// Update i
i = 0;
}
}
How can I modify it to receive data from a specific client and send also to specific client?
there is the method send(); and recv(); but I don't know How the variable NewSocket tell to which client is sending it