Thread: TCP/IP client & echo server

Hello,
I am creating a simple chat program as my final project for a self taught c++ programming class.

Heres what i want to accomplish:
client: you type something in the client and push enter and it sends that to the server. the client also prints out anything the server echos back to the client.

server: the server accepts connections from the client(s) and then the server takes any text it gets from the clients and echos it back out to all the clients. Making a simple chat program.

This is a fairly simple process but im finding it fairly difficult to work with multiple clients.

What i need is help figuring out the process to do this. Here is my understanding of what should happen.

client / server:
create socket
make socket NON-blocking
bind to it
listen
loop select and if read or write flags are triggured read or write

im not sure how the sockets work. i have a listens socket and i guess im suppost to make a new connection for every client but once my code gets past the accepting of the new clients and i go to write it just quits. and the write flag of select never even gets triggured. This is just something to think about, as soon as i get home ill post the actual code i have so far.

thanks,
jordan

if you have any other ideas for how i could accomplish this please post (besides using fork etc)

Code:

// includes
#include <iostream>
#include <stdio.h>
#include <stdlib.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <errno.h>
#include <sys/types.h>
#include <strings.h>
#include <unistd.h>
#include <time.h>
#include <fcntl.h>

// define constants
#define SA struct sockaddr
#define BUFFERSIZE 1024

// main program
int main(int argc, char **argv)
{

printf("Server started\n");

// define variables
fd_set read_flags,write_flags;
int listens, work, x, checking,i,wx;
struct sockaddr_in servaddr;
char buff[1024];
int clients[26];
struct timeval timer; 
i=0; 

// creates socket
listens = socket(AF_INET, SOCK_STREAM, 0);

// sets servaddr to all zeros
bzero(&servaddr, sizeof(servaddr));

// sets servaddr
servaddr.sin_family = AF_INET;
servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
servaddr.sin_port = htons(2007);

// making listens socket non-blocking
x=fcntl(listens,F_GETFL,0);
fcntl(listens,F_SETFL,x | O_NONBLOCK);

// bind
if(bind(listens, (SA *) &servaddr, sizeof(servaddr))<0){
printf("Bind Failed!\n");
}
  
// listening
if (listen(listens, BUFFERSIZE)<0){
printf("Listen Failed!\n");
}
snprintf(buff, sizeof(buff), "Hello people, i came from a server woot");

for ( ; ; ) {
timer.tv_sec = 1;
timer.tv_usec = 0;
FD_ZERO(&read_flags);
FD_ZERO(&write_flags);
FD_SET(listens, &read_flags);
FD_SET(listens, &write_flags);
select(listens+1, &read_flags,&write_flags,(fd_set*)0,&timer);
if (FD_ISSET(listens, &read_flags)) {
    FD_CLR(listens, &read_flags);
    if(clients[i]=accept(listens, (SA *) NULL, NULL)>0){
    std::cout << "New client " << i << ": Return: " << clients[i] << " \n";
    wx=write( listens, buff, strlen(buff));
    std::cout << "Returned: " << wx;
    i++;
    }

    }
if (FD_ISSET(listens, &read_flags)) {
 FD_CLR(listens, &write_flags);
 std::cout << "go ahead and write\n";
}

}
}

Thats what i got so far