/* Select_EchoMonitored.c
 * Copyright 2016 Agustin Gonzalez  
 */
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <string.h>

int main(int argc, char **argv) {
    char buf[10];
    int es, ms, n, ec, mc, len;
    struct sockaddr_in name;
    int nbytes = 0;
    fd_set readfds, readfdsCopy;
  
    es = socket(AF_INET, SOCK_STREAM, 0);
    name.sin_family = AF_INET;
    name.sin_port = htons(atoi(argv[1]));
    name.sin_addr.s_addr = htonl(INADDR_ANY);
    len = sizeof(struct sockaddr_in);
    bind(es, (struct sockaddr *) &name, len);
    listen(es, 1);

    ms = socket(AF_INET, SOCK_STREAM, 0);
    name.sin_family = AF_INET;
    name.sin_port = htons(atoi(argv[2]));
    name.sin_addr.s_addr = htonl(INADDR_ANY);
    len = sizeof(struct sockaddr_in);
    bind(ms, (struct sockaddr *) &name, len);
    listen(ms, 1);
    
    FD_ZERO(&readfdsCopy);
    FD_SET(es,&readfdsCopy);
    FD_SET(ms,&readfdsCopy);
    while (1) { 
      memcpy(&readfds, &readfdsCopy, sizeof(fd_set));
      n = select(FD_SETSIZE, &readfds, (fd_set *) 0, (fd_set *) 0, NULL);  
      if (n>0) {
        if (FD_ISSET(es, &readfds)) {
          ec = accept(es, (struct sockaddr *) &name, &len);
          FD_SET(ec, &readfdsCopy);
        }
        if (FD_ISSET(ec, &readfds)) {
          if ((n = recv(ec, buf, sizeof(buf), 0)) > 0) {
            send(ec, buf, n, 0);
            nbytes += n;
          } else break;
        }
        if (FD_ISSET(ms, &readfds)) {
          mc = accept(ms, (struct sockaddr *) &name, &len);
          sprintf(buf, "%i", nbytes);
          send(mc, buf, strlen(buf), 0);
          close(mc);
        }
      }
    }
    close(ms);
    close(ec);
    close(es);
	exit (0);
}