Improve the SLIP driver: allow dynamic creation of SLIP interfaces.

[tripe] / tun-linux.c

/* -*-c-*-
 *
 * $Id$
 *
 * Tunnel interface based on Linux TUN/TAP driver
 *
 * (c) 2003 Straylight/Edgeware
 */

/*----- Licensing notice --------------------------------------------------* 
 *
 * This file is part of Trivial IP Encryption (TrIPE).
 *
 * TrIPE is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 * 
 * TrIPE is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with TrIPE; if not, write to the Free Software Foundation,
 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

/*----- Header files ------------------------------------------------------*/

#include "tripe.h"

#include <sys/ioctl.h>

/*----- Main code ---------------------------------------------------------*/

#if TUN_TYPE != TUN_LINUX
#  error "Tunnel type mismatch: fix the Makefile"
#endif

/* --- @t_read@ --- *
 *
 * Arguments:	@int fd@ = file descriptor to read
 *		@unsigned mode@ = what's happened
 *		@void *v@ = pointer to tunnel block
 *
 * Returns:	---
 *
 * Use:		Reads data from the tunnel.
 */

static void t_read(int fd, unsigned mode, void *v)
{
  tunnel *t = v;
  ssize_t n;
  buf b;

  n = read(fd, buf_i, sizeof(buf_i));
  if (n < 0) {
    a_warn("TUN %s read-error -- %s", t->ifn, strerror(errno));
    return;
  }
  IF_TRACING(T_TUNNEL, {
    trace(T_TUNNEL, "tunnel: packet arrived");
    trace_block(T_PACKET, "tunnel: packet contents", buf_i, n);
  })
  buf_init(&b, buf_i, n);
  p_tun(t->p, &b);
}

/* --- @tun_init@ --- *
 *
 * Arguments:	---
 *
 * Returns:	---
 *
 * Use:		Initializes the tunneling system.  Maybe this will require
 *		opening file descriptors or something.
 */

void tun_init(void)
{
  return;
}

/* --- @tun_create@ --- *
 *
 * Arguments:	@tunnel *t@ = pointer to tunnel block
 *		@peer *p@ = pointer to peer block
 *
 * Returns:	Zero if it worked, nonzero on failure.
 *
 * Use:		Initializes a new tunnel.
 */

int tun_create(tunnel *t, peer *p)
{
  int fd;
  int f;
  struct ifreq iff;

  if ((fd = open("/dev/net/tun", O_RDWR)) < 0) {
    a_warn("TUN - open-error /dev/net/tun -- %s", strerror(errno));
    return (-1);
  }
  fdflags(fd, O_NONBLOCK, O_NONBLOCK, FD_CLOEXEC, FD_CLOEXEC);
  iff.ifr_name[0] = 0;
  iff.ifr_flags = IFF_TUN | IFF_NO_PI;
  if ((f = ioctl(fd, TUNSETIFF, &iff)) < 0) {
    a_warn("TUN - linux config-error -- %s", strerror(errno));
    close(fd);
    return (-1);
  }
  t->p = p;
  sel_initfile(&sel, &t->f, fd, SEL_READ, t_read, t);
  sel_addfile(&t->f);
  iff.ifr_name[IFNAMSIZ - 1] = 0;
  strcpy(t->ifn, iff.ifr_name);
  T( trace(T_TUNNEL, "tunnel: attached interface %s to peer `%s'",
	   t->ifn, p_name(p)); )
  return (0);
}

/* --- @tun_ifname@ --- *
 *
 * Arguments:	@tunnel *t@ = pointer to tunnel block
 *
 * Returns:	A pointer to the tunnel's interface name.
 */

const char *tun_ifname(tunnel *t)
{
  return (t->ifn);
}

/* --- @tun_inject@ --- *
 *
 * Arguments:	@tunnel *t@ = pointer to tunnel block
 *		@buf *b@ = buffer to send
 *
 * Returns:	---
 *
 * Use:		Injects a packet into the local network stack.
 */

void tun_inject(tunnel *t, buf *b)
{
  IF_TRACING(T_TUNNEL, {
    trace(T_TUNNEL, "tunnel: inject decrypted packet");
    trace_block(T_PACKET, "tunnel: packet contents", BBASE(b), BLEN(b));
  })
  write(t->f.fd, BBASE(b), BLEN(b));
}

/* --- @tun_destroy@ --- *
 *
 * Arguments:	@tunnel *t@ = pointer to tunnel block
 *
 * Returns:	---
 *
 * Use:		Destroys a tunnel.
 */

void tun_destroy(tunnel *t)
{
  sel_rmfile(&t->f);
  close(t->f.fd);
}

/*----- That's all, folks -------------------------------------------------*/