#include <stdio.h>
#include <sys/types.h> 
#include <sys/socket.h> 
#include <sys/un.h>
#include <string.h>
#include <stdlib.h>
#include <sys/time.h>

#define SOCKETNAME  "selectServerSocket"

int
main(void)
{
        char buf[1024];         /* Buffer for messages to others. */
        int s;                          /* Listen socket */
        int ns;                         /* Socket for first connection. */
        int ns2;                        /* Socket for second connection. */
        int len;                        /* len of sockaddr */   
        int maxfd;                      /* descriptors up to maxfd-1 polled*/
        int nread;                      /* # chars on read()*/
        int nready;                     /* # descriptors ready. */
        struct sockaddr_un name;
        fd_set fds;                     /* Set of file descriptors to poll*/

        /* Remove any previous socket.*/
        unlink(SOCKETNAME);

        /* Create the socket. */

        if ((s = socket(AF_UNIX, SOCK_STREAM, 0)) < 0)
        {
        perror("socket");
        exit(1);
         }

        /* Create the address of the server.*/

        memset(&name, 0, sizeof(struct sockaddr_un));

        name.sun_family = AF_UNIX;
        strcpy(name.sun_path, SOCKETNAME);
        len = sizeof(name.sun_family) + strlen(name.sun_path);

        /*Bind the socket to the address.*/

        if (bind(s, (struct sockaddr *) &name, len) < 0) {
        perror("bind");
        exit(1);
        }
        
        /* Listen for connections. */
        if (listen(s, 5) < 0){
        perror( "listen");
        exit(1);
        }


        /*Accept a connection.*/
        if ((ns = accept(s, (struct sockaddr *) &name, &len)) < 0) {
        perror("accept");
        exit(1);
        }

        /* Accept another connection. */
        if ((ns2 = accept(s, (struct sockaddr *) &name, &len)) < 0) {
        perror("accept");
        exit(1);
        }
        
        maxfd = (ns > ns2 ? ns : ns2) + 1;
        while(1){
                /* Set up polling using select. */
                FD_ZERO(&fds);
                FD_SET(ns,&fds);
                FD_SET(ns2,&fds);

                /* Wait for some input. */
                nready = select(maxfd, &fds, (fd_set *) 0, (fd_set *) 0,
                                (struct timeval *) 0);
                /* If either descriptor has some input,
                   read it and copy it to the other. */

                if( FD_ISSET(ns, &fds))
                {
                        nread = recv(ns, buf, sizeof(buf), 0);
                        /* If error or eof, terminate. */
                        if(nread < 1){
                                close(ns);
                                close(ns2);
                                exit(0);
                        }
                        send( ns2, buf, nread, 0);
                }

                if( FD_ISSET(ns2, &fds))
                {
                        nread = recv(ns2, buf, sizeof(buf), 0);
                        /* If error or eof, terminate. */
                        if(nread < 1){
                                close(ns);
                                close(ns2);
                                exit(0);
                        }
                        send( ns, buf, nread, 0);
                }
        } 
}