mdw@git.distorted.org.uk Git - tripe/blob - tun-linux.c

   1 /* -*-c-*-
   2  *
   3  * $Id$
   4  *
   5  * Tunnel interface based on Linux TUN/TAP driver
   6  *
   7  * (c) 2003 Straylight/Edgeware
   8  */
   9
  10 /*----- Licensing notice --------------------------------------------------*
  11  *
  12  * This file is part of Trivial IP Encryption (TrIPE).
  13  *
  14  * TrIPE is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU General Public License as published by
  16  * the Free Software Foundation; either version 2 of the License, or
  17  * (at your option) any later version.
  18  *
  19  * TrIPE is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22  * GNU General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU General Public License
  25  * along with TrIPE; if not, write to the Free Software Foundation,
  26  * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  27  */
  28
  29 /*----- Header files ------------------------------------------------------*/
  30
  31 #define TUN_INTERNALS
  32
  33 #include "tripe.h"
  34
  35 #ifdef TUN_LINUX
  36 #  include <sys/ioctl.h>
  37 #  include <linux/if.h>
  38 #  include <linux/if_tun.h>
  39 #endif
  40
  41 /*----- Main code ---------------------------------------------------------*/
  42
  43 #ifdef TUN_LINUX
  44
  45 struct tunnel {
  46   const tunnel_ops *ops;                /* Pointer to operations */
  47   sel_file f;                           /* Selector for TUN/TAP device */
  48   struct peer *p;                       /* Pointer to my peer */
  49   char ifn[IFNAMSIZ];                   /* Interface name buffer */
  50 };
  51
  52 /* --- @t_read@ --- *
  53  *
  54  * Arguments:   @int fd@ = file descriptor to read
  55  *              @unsigned mode@ = what's happened
  56  *              @void *v@ = pointer to tunnel block
  57  *
  58  * Returns:     ---
  59  *
  60  * Use:         Reads data from the tunnel.
  61  */
  62
  63 static void t_read(int fd, unsigned mode, void *v)
  64 {
  65   tunnel *t = v;
  66   ssize_t n;
  67   buf b;
  68
  69   n = read(fd, buf_i, sizeof(buf_i));
  70   if (n < 0) {
  71     a_warn("TUN %s read-error -- %s", t->ifn, strerror(errno));
  72     return;
  73   }
  74   IF_TRACING(T_TUNNEL, {
  75     trace(T_TUNNEL, "tun-linux: packet arrived");
  76     trace_block(T_PACKET, "tun-linux: packet contents", buf_i, n);
  77   })
  78   buf_init(&b, buf_i, n);
  79   p_tun(t->p, &b);
  80 }
  81
  82 /* --- @t_init@ --- *
  83  *
  84  * Arguments:   ---
  85  *
  86  * Returns:     ---
  87  *
  88  * Use:         Initializes the tunneling system.  Maybe this will require
  89  *              opening file descriptors or something.
  90  */
  91
  92 static void t_init(void) { return; }
  93
  94 /* --- @t_create@ --- *
  95  *
  96  * Arguments:   @peer *p@ = pointer to peer block
  97  *
  98  * Returns:     A tunnel block if it worked, or null on failure.
  99  *
 100  * Use:         Initializes a new tunnel.
 101  */
 102
 103 static tunnel *t_create(peer *p)
 104 {
 105   int fd;
 106   int f;
 107   struct ifreq iff;
 108   tunnel *t;
 109
 110   if ((fd = open("/dev/net/tun", O_RDWR)) < 0) {
 111     a_warn("TUN - open-error /dev/net/tun -- %s", strerror(errno));
 112     return (0);
 113   }
 114   fdflags(fd, O_NONBLOCK, O_NONBLOCK, FD_CLOEXEC, FD_CLOEXEC);
 115   memset(&iff, 0, sizeof(iff));
 116   iff.ifr_name[0] = 0;
 117   iff.ifr_flags = IFF_TUN | IFF_NO_PI;
 118   if ((f = ioctl(fd, TUNSETIFF, &iff)) < 0) {
 119     a_warn("TUN - linux config-error -- %s", strerror(errno));
 120     close(fd);
 121     return (0);
 122   }
 123   t = CREATE(tunnel);
 124   t->ops = &tun_linux;
 125   t->p = p;
 126   sel_initfile(&sel, &t->f, fd, SEL_READ, t_read, t);
 127   sel_addfile(&t->f);
 128   iff.ifr_name[IFNAMSIZ - 1] = 0;
 129   strcpy(t->ifn, iff.ifr_name);
 130   T( trace(T_TUNNEL, "tun-linux: attached interface %s to peer `%s'",
 131            t->ifn, p_name(p)); )
 132   return (t);
 133 }
 134
 135 /* --- @t_ifname@ --- *
 136  *
 137  * Arguments:   @tunnel *t@ = pointer to tunnel block
 138  *
 139  * Returns:     A pointer to the tunnel's interface name.
 140  */
 141
 142 static const char *t_ifname(tunnel *t) { return (t->ifn); }
 143
 144 /* --- @t_inject@ --- *
 145  *
 146  * Arguments:   @tunnel *t@ = pointer to tunnel block
 147  *              @buf *b@ = buffer to send
 148  *
 149  * Returns:     ---
 150  *
 151  * Use:         Injects a packet into the local network stack.
 152  */
 153
 154 static void t_inject(tunnel *t, buf *b)
 155 {
 156   IF_TRACING(T_TUNNEL, {
 157     trace(T_TUNNEL, "tun-linux: inject decrypted packet");
 158     trace_block(T_PACKET, "tunnel: packet contents", BBASE(b), BLEN(b));
 159   })
 160   write(t->f.fd, BBASE(b), BLEN(b));
 161 }
 162
 163 /* --- @t_destroy@ --- *
 164  *
 165  * Arguments:   @tunnel *t@ = pointer to tunnel block
 166  *
 167  * Returns:     ---
 168  *
 169  * Use:         Destroys a tunnel.
 170  */
 171
 172 static void t_destroy(tunnel *t)
 173 {
 174   sel_rmfile(&t->f);
 175   close(t->f.fd);
 176   DESTROY(t);
 177 }
 178
 179 const tunnel_ops tun_linux = {
 180   "linux",
 181   t_init,
 182   t_create,
 183   t_ifname,
 184   t_inject,
 185   t_destroy
 186 };
 187
 188 #endif
 189
 190 /*----- That's all, folks -------------------------------------------------*/