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

   1 /* -*-c-*-
   2  *
   3  * $Id$
   4  *
   5  * Tunnel interface for 4.4BSD-derived systems
   6  *
   7  * (c) 2001 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 /*----- Main code ---------------------------------------------------------*/
  36
  37 #ifdef TUN_BSD
  38
  39 struct tunnel {
  40   const tunnel_ops *ops;                /* Pointer to operations */
  41   sel_file f;                           /* Selector for tunnel device */
  42   struct peer *p;                       /* Pointer to my peer */
  43   unsigned n;                           /* Number of my tunnel device */
  44 };
  45
  46 /* --- @t_read@ --- *
  47  *
  48  * Arguments:   @int fd@ = file descriptor to read
  49  *              @unsigned mode@ = what's happened
  50  *              @void *v@ = pointer to tunnel block
  51  *
  52  * Returns:     ---
  53  *
  54  * Use:         Reads data from the tunnel.
  55  */
  56
  57 static void t_read(int fd, unsigned mode, void *v)
  58 {
  59   tunnel *t = v;
  60   ssize_t n;
  61   buf b;
  62
  63   n = read(fd, buf_i, sizeof(buf_i));
  64   if (n < 0) {
  65     a_warn("TUN", "%s", p_ifname(t->p), "read-error", "?ERRNO", A_END);
  66     return;
  67   }
  68   IF_TRACING(T_TUNNEL, {
  69     trace(T_TUNNEL, "tun-bsd: packet arrived");
  70     trace_block(T_PACKET, "tun-bsd: packet contents", buf_i, n);
  71   })
  72   buf_init(&b, buf_i, n);
  73   p_tun(t->p, &b);
  74 }
  75
  76 /* --- @t_init@ --- *
  77  *
  78  * Arguments:   ---
  79  *
  80  * Returns:     ---
  81  *
  82  * Use:         Initializes the tunneling system.  Maybe this will require
  83  *              opening file descriptors or something.
  84  */
  85
  86 static void t_init(void) { return; }
  87
  88 /* --- @t_create@ --- *
  89  *
  90  * Arguments:   @peer *p@ = pointer to peer block
  91  *              @char **ifn@ = where to put the interface name
  92  *
  93  * Returns:     A tunnel block if it worked, or null on failure.
  94  *
  95  * Use:         Initializes a new tunnel.
  96  */
  97
  98 static tunnel *t_create(peer *p, char **ifn)
  99 {
 100   int fd;
 101   unsigned n;
 102   tunnel *t;
 103   char buf[16];
 104
 105   n = 0;
 106   for (;;) {
 107     sprintf(buf, "/dev/tun%u", n);
 108     if ((fd = open(buf, O_RDWR)) >= 0)
 109       break;
 110     switch (errno) {
 111       case EBUSY:
 112         T( trace(T_TUNNEL, "tunnel device %u busy: skipping", n); )
 113         break;
 114       case ENOENT:
 115         a_warn("TUN", "-", "bsd", "no-tunnel-devices", A_END);
 116         return (0);
 117       default:
 118         a_warn("TUN", "-", "open-error", "%s", buf, "?ERRNO", A_END);
 119         break;
 120     }
 121     n++;
 122   }
 123
 124   t = CREATE(tunnel);
 125   t->ops = &tun_bsd;
 126   fdflags(fd, O_NONBLOCK, O_NONBLOCK, FD_CLOEXEC, FD_CLOEXEC);
 127   t->p = p;
 128   t->n = n;
 129   sel_initfile(&sel, &t->f, fd, SEL_READ, t_read, t);
 130   sel_addfile(&t->f);
 131   *ifn = xstrdup(buf + 5);
 132   T( trace(T_TUNNEL, "tun-bsd: attached interface %s to peer `%s'",
 133            *ifn, p_name(p)); )
 134   return (t);
 135 }
 136
 137 /* --- @t_inject@ --- *
 138  *
 139  * Arguments:   @tunnel *t@ = pointer to tunnel block
 140  *              @buf *b@ = buffer to send
 141  *
 142  * Returns:     ---
 143  *
 144  * Use:         Injects a packet into the local network stack.
 145  */
 146
 147 static void t_inject(tunnel *t, buf *b)
 148 {
 149   IF_TRACING(T_TUNNEL, {
 150     trace(T_TUNNEL, "tun-bsd: inject decrypted packet");
 151     trace_block(T_PACKET, "tun-bsd: packet contents", BBASE(b), BLEN(b));
 152   })
 153   write(t->f.fd, BBASE(b), BLEN(b));
 154 }
 155
 156 /* --- @t_destroy@ --- *
 157  *
 158  * Arguments:   @tunnel *t@ = pointer to tunnel block
 159  *
 160  * Returns:     ---
 161  *
 162  * Use:         Destroys a tunnel.
 163  */
 164
 165 static void t_destroy(tunnel *t)
 166 {
 167   sel_rmfile(&t->f);
 168   close(t->f.fd);
 169   DESTROY(t);
 170 }
 171
 172 const tunnel_ops tun_bsd = {
 173   "bsd",
 174   t_init,
 175   t_create,
 176   0,
 177   t_inject,
 178   t_destroy
 179 };
 180
 181 #endif
 182
 183 /*----- That's all, folks -------------------------------------------------*/