socket2socket.c

linux 上端口映射程序源代码

/*
 * socket2socket.c: Joins two sockets together
 *
 * Copyright (C) 2003 Miguelanxo Otero Salgueiro
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the tems of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 */

#include <signal.h>
#include "desproxy.h"
#define MAX_CONNECTIONS 10
#define PROGRAM_VERSION VERSION
#define PROGRAM_NAME "socket2socket"

unsigned char client_socket_is_free[MAX_CONNECTIONS];
int client_socket[MAX_CONNECTIONS];
int remote_socket[MAX_CONNECTIONS];

void
EOC_s2s (int index)
{

  close (client_socket[index]);
  close (remote_socket[index]);
  FD_CLR (client_socket[index], &mask);
  FD_CLR (remote_socket[index], &mask);
  client_socket_is_free[index] = 1;
  printf (gettext ("End of connection\n"));
  fflush (stdout);
  fflush (stderr);
}

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

  int request_socket, addrlen;
  int index, count;
  struct sockaddr_in server;
  struct sockaddr_in remote;
  struct hostent *remote_hostent;
  char *remote_host;
  char *remote_port;
  char *local_port;
  int nfound, maxfd;
  struct timeval timeout;
  int outfile = 1;
  char *outfilename;

  signal (SIGPIPE, SIG_IGN);
  print_program_version (PROGRAM_NAME, PROGRAM_VERSION);

  if ((argc < 4) || (argc > 5))
    {
      printf (gettext
	      ("Usage: socket2socket remote_host remote_port local_port"
	       " [logfile]\n\n"));
      exit (1);
    }
  remote_host = argv[1];
  remote_port = argv[2];
  local_port = argv[3];

  if (argc == 5)
    {
      outfilename = argv[4];
      if ((outfile =
	   open (outfilename, O_CREAT | O_WRONLY, S_IREAD | S_IWRITE)) == -1)
	{
	  perror ("open");
	  exit (1);
	}
    }
  if ((request_socket = socket (AF_INET, SOCK_STREAM, 0)) < 0)
    {
      perror ("socket");
      exit (1);
    }
  memset (&server, 0, sizeof server);
  server.sin_family = AF_INET;
  server.sin_addr.s_addr = INADDR_ANY;
  server.sin_port = htons (atoi (local_port));
  if ((bind (request_socket, (struct sockaddr *) &server, sizeof server)) < 0)
    {
      perror ("bind");
      exit (1);
    }
  if (listen (request_socket, SOMAXCONN) < 0)
    {
      perror ("listen");
      exit (1);
    }
  printf (gettext ("Listening in port %d\n"), atoi (local_port));
  printf (gettext ("Press <Control+C> to Quit\n\n"));

  mark_all_client_sockets_as_free ();
  FD_ZERO (&mask);
  FD_SET (request_socket, &mask);
  maxfd = request_socket;
  while (1)
    {
      rmask = mask;
      timeout.tv_sec = 5;
      timeout.tv_usec = 0;
      nfound = select (maxfd + 1, &rmask, NULL, NULL, &timeout);
      if (nfound < 0)
	{
	  if (errno == EINTR)
	    {
	      printf (gettext ("Interrupted by system call\n"));
	      continue;
	    }
	  perror ("select");
	  exit (1);
	}

      if (FD_ISSET (request_socket, &rmask))
	{
	  addrlen = sizeof (remote);
	  for (index = 0; index < MAX_CONNECTIONS; index++)
	    if (client_socket_is_free[index])
	      break;
	  if (index == MAX_CONNECTIONS)
	    {
	      printf (gettext
		      ("There are no connections available at this time\n"));
	    }
	  else
	    {
	      client_socket_is_free[index] = 0;
	      client_socket[index] =
		accept (request_socket, (struct sockaddr *) &remote, &addrlen);
	      if (client_socket[index] < 0)
		{
		  perror ("accept");
		  exit (1);
		}
	      printf (gettext ("Connection request from %s, port %d\n"),
		      inet_ntoa (remote.sin_addr), ntohs (remote.sin_port));
	      if (client_socket[index] > maxfd)
		maxfd = client_socket[index];
	      printf (gettext ("Connecting to remote host (%s:%s)\n"),
		      remote_host, remote_port);
	      if ((remote_socket[index] = socket (AF_INET, SOCK_STREAM, 0)) < 0)
		{
		  perror ("socket");
		  exit (1);
		}
	      if (remote_socket[index] > maxfd)
		maxfd = remote_socket[index];
	      if ((remote_hostent = gethostbyname (remote_host)) == 0)
		{
		  perror ("gethostbyname");
		  exit (1);
		}
	      memset (&remote, 0, sizeof remote);
	      remote.sin_family = AF_INET;
	      memcpy (&remote.sin_addr, remote_hostent->h_addr,
		      remote_hostent->h_length);
	      remote.sin_port = htons (atoi (remote_port));
	      if (connect
		  (remote_socket[index], (struct sockaddr *) &remote,
		   sizeof remote) < 0)
		{
		  close (remote_socket[index]);
		  printf ("\n");
		  perror ("connect");
		  exit (1);
		}
	      printf (gettext ("Bidirectional connection stablished\n"));
	      printf ("(%s:%s) <-> (localhost)\n", remote_host, remote_port);
	      FD_SET (remote_socket[index], &mask);
	      FD_SET (client_socket[index], &mask);
	    }
	}
      for (index = 0; index < MAX_CONNECTIONS; index++)
	{
	  if (!client_socket_is_free[index])
	    {
	      if (FD_ISSET (remote_socket[index], &rmask))
		{
		  printf ("remote -> local (connection #%d) ", index);
		  fflush (stdout);
		  if ((count =
		       read (remote_socket[index], buffer,
			     sizeof (buffer))) == -1)
		    {
		      perror ("read");
		      EOC_s2s (index);
		    }
		  else
		    {
		      if (count == 0)
			{
			  EOC_s2s (index);
			}
		      else
			{
			  if ((count =
			       write (client_socket[index], buffer,
				      count)) == -1)
			    {
			      perror ("\nwrite");
			      fflush (stderr);
			      EOC_s2s (index);
			    }
			  else
			    {
			      if (argc == 5)
				{
				  write (outfile, "[R->L]", 6);
				  write (outfile, buffer, count);
				  fsync (outfile);
				}
			      printf (" %d Bytes\n", count);
			      fflush (stdout);
			    }
			}
		    }
		}
	    }
	  if (!client_socket_is_free[index])
	    {
	      if (FD_ISSET (client_socket[index], &rmask))
		{
		  printf ("local -> remote (connection #%d)", index);
		  fflush (stdout);
		  if ((count =
		       read (client_socket[index], buffer,
			     sizeof (buffer))) == -1)
		    {
		      perror ("read");
		      EOC_s2s (index);
		    }
		  else
		    {
		      if (count == 0)
			{
			  EOC_s2s (index);
			}
		      else
			{
			  if ((count =
			       write (remote_socket[index], buffer,
				      count)) == -1)
			    {
			      perror ("write");
			      EOC_s2s (index);
			    }
			  else
			    {
			      if (argc == 5)
				{
				  write (outfile, "[L->R]", 6);
				  write (outfile, buffer, count);
				  fsync (outfile);
				}
			      printf (" %d bytes\n", count);
			      fflush (stdout);
			    }
			}
		    }
		}
	    }
	}
      fflush (stdout);
      fflush (stderr);
    }
  exit (0);
}