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

   1 /* -*-c-*-
   2  *
   3  * Tunnel interface for 4.4BSD-derived systems
   4  *
   5  * (c) 2001 Straylight/Edgeware
   6  */
   7
   8 /*----- Licensing notice --------------------------------------------------*
   9  *
  10  * This file is part of Trivial IP Encryption (TrIPE).
  11  *
  12  * TrIPE is free software; you can redistribute it and/or modify
  13  * it under the terms of the GNU General Public License as published by
  14  * the Free Software Foundation; either version 2 of the License, or
  15  * (at your option) any later version.
  16  *
  17  * TrIPE is distributed in the hope that it will be useful,
  18  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20  * GNU General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU General Public License
  23  * along with TrIPE; if not, write to the Free Software Foundation,
  24  * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  25  */
  26
  27 /*----- Header files ------------------------------------------------------*/
  28
  29 #define TUN_INTERNALS
  30
  31 #include "tripe.h"
  32
  33 /*----- Main code ---------------------------------------------------------*/
  34
  35 #ifdef TUN_BSD
  36
  37 struct tunnel {
  38   const tunnel_ops *ops;                /* Pointer to operations */
  39   sel_file f;                           /* Selector for tunnel device */
  40   struct peer *p;                       /* Pointer to my peer */
  41 };
  42
  43 /* --- @t_read@ --- *
  44  *
  45  * Arguments:   @int fd@ = file descriptor to read
  46  *              @unsigned mode@ = what's happened
  47  *              @void *v@ = pointer to tunnel block
  48  *
  49  * Returns:     ---
  50  *
  51  * Use:         Reads data from the tunnel.
  52  */
  53
  54 static void t_read(int fd, unsigned mode, void *v)
  55 {
  56   tunnel *t = v;
  57   ssize_t n;
  58   buf b;
  59
  60   n = read(fd, buf_i, sizeof(buf_i));
  61   if (n < 0) {
  62     a_warn("TUN", "%s", p_ifname(t->p), "read-error", "?ERRNO", A_END);
  63     return;
  64   }
  65   IF_TRACING(T_TUNNEL, {
  66     trace(T_TUNNEL, "tun-bsd: packet arrived");
  67     trace_block(T_PACKET, "tun-bsd: packet contents", buf_i, n);
  68   })
  69   buf_init(&b, buf_i, n);
  70   p_tun(t->p, &b);
  71 }
  72
  73 /* --- @t_init@ --- *
  74  *
  75  * Arguments:   ---
  76  *
  77  * Returns:     ---
  78  *
  79  * Use:         Initializes the tunneling system.  Maybe this will require
  80  *              opening file descriptors or something.
  81  */
  82
  83 static void t_init(void) { return; }
  84
  85 /* --- @t_open@ --- *
  86  *
  87  * Arguments:   @char **ifn@ = where to put the interface name
  88  *
  89  * Returns:     A file descriptor, or @-1@ on failure.
  90  *
  91  * Use:         Opens a tunnel device.  This will run with root privileges
  92  *              even if the rest of the server has dropped them.
  93  */
  94
  95 static int t_open(char **ifn)
  96 {
  97   int fd;
  98   unsigned n;
  99   char buf[16];
 100
 101   n = 0;
 102   for (;;) {
 103     sprintf(buf, "/dev/tun%u", n);
 104     if ((fd = open(buf, O_RDWR)) >= 0)
 105       break;
 106     switch (errno) {
 107       case EBUSY:
 108        T( trace(T_TUNNEL, "tunnel device %u busy: skipping", n); )
 109        break;
 110       case ENOENT:
 111        a_warn("TUN", "-", "bsd", "no-tunnel-devices", A_END);
 112        return (-1);
 113       default:
 114        a_warn("TUN", "-", "open-error", "%s", buf, "?ERRNO", A_END);
 115        break;
 116     }
 117     n++;
 118   }
 119   return (fd);
 120 }
 121
 122 /* --- @t_create@ --- *
 123  *
 124  * Arguments:   @peer *p@ = pointer to peer block
 125  *              @int fd@ = file descriptor of tunnel device
 126  *              @char **ifn@ = where to put the interface name
 127  *
 128  * Returns:     A tunnel block if it worked, or null on failure.
 129  *
 130  * Use:         Initializes a new tunnel.
 131  */
 132
 133 static tunnel *t_create(peer *p, int fd, char **ifn)
 134 {
 135   tunnel *t;
 136
 137   fdflags(fd, O_NONBLOCK, O_NONBLOCK, FD_CLOEXEC, FD_CLOEXEC);
 138   t = CREATE(tunnel);
 139   t->ops = &tun_bsd;
 140   t->p = p;
 141   sel_initfile(&sel, &t->f, fd, SEL_READ, t_read, t);
 142   sel_addfile(&t->f);
 143   return (t);
 144 }
 145
 146 /* --- @t_inject@ --- *
 147  *
 148  * Arguments:   @tunnel *t@ = pointer to tunnel block
 149  *              @buf *b@ = buffer to send
 150  *
 151  * Returns:     ---
 152  *
 153  * Use:         Injects a packet into the local network stack.
 154  */
 155
 156 static void t_inject(tunnel *t, buf *b)
 157 {
 158   IF_TRACING(T_TUNNEL, {
 159     trace(T_TUNNEL, "tun-bsd: inject decrypted packet");
 160     trace_block(T_PACKET, "tun-bsd: packet contents", BBASE(b), BLEN(b));
 161   })
 162   write(t->f.fd, BBASE(b), BLEN(b));
 163 }
 164
 165 /* --- @t_destroy@ --- *
 166  *
 167  * Arguments:   @tunnel *t@ = pointer to tunnel block
 168  *
 169  * Returns:     ---
 170  *
 171  * Use:         Destroys a tunnel.
 172  */
 173
 174 static void t_destroy(tunnel *t)
 175   { sel_rmfile(&t->f); close(t->f.fd); DESTROY(t); }
 176
 177 const tunnel_ops tun_bsd = {
 178   "bsd",
 179   t_init,
 180   t_open,
 181   t_create,
 182   0,
 183   t_inject,
 184   t_destroy
 185 };
 186
 187 #endif
 188
 189 /*----- That's all, folks -------------------------------------------------*/