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

   1 /* -*-c-*-
   2  *
   3  * $Id: tun-bsd.c,v 1.2 2003/11/29 23:49:32 mdw Exp $
   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 /*----- Revision history --------------------------------------------------*
  30  *
  31  * $Log: tun-bsd.c,v $
  32  * Revision 1.2  2003/11/29 23:49:32  mdw
  33  * Debianization.
  34  *
  35  * Revision 1.1  2001/02/05 19:48:18  mdw
  36  * Initial support for BSD tunnel devices.
  37  *
  38  */
  39
  40 /*----- Header files ------------------------------------------------------*/
  41
  42 #include "tripe.h"
  43
  44 /*----- Main code ---------------------------------------------------------*/
  45
  46 #if TUN_TYPE != TUN_BSD
  47 #  error "Tunnel type mismatch: fix the Makefile"
  48 #endif
  49
  50 /* --- @t_read@ --- *
  51  *
  52  * Arguments:   @int fd@ = file descriptor to read
  53  *              @unsigned mode@ = what's happened
  54  *              @void *v@ = pointer to tunnel block
  55  *
  56  * Returns:     ---
  57  *
  58  * Use:         Reads data from the tunnel.
  59  */
  60
  61 void t_read(int fd, unsigned mode, void *v)
  62 {
  63   tunnel *t = v;
  64   ssize_t n;
  65   buf b;
  66
  67   n = read(fd, buf_i, sizeof(buf_i));
  68   if (n < 0) {
  69     a_warn("tunnel read failed (%s): %s", tun_ifname(t), strerror(errno));
  70     return;
  71   }
  72   IF_TRACING(T_TUNNEL, {
  73     trace(T_TUNNEL, "tunnel: packet arrived");
  74     trace_block(T_PACKET, "tunnel: packet contents", buf_i, n);
  75   })
  76   buf_init(&b, buf_i, n);
  77   p_tun(t->p, &b);
  78 }
  79
  80 /* --- @tun_init@ --- *
  81  *
  82  * Arguments:   ---
  83  *
  84  * Returns:     ---
  85  *
  86  * Use:         Initializes the tunneling system.  Maybe this will require
  87  *              opening file descriptors or something.
  88  */
  89
  90 void tun_init(void)
  91 {
  92   return;
  93 }
  94
  95 /* --- @tun_create@ --- *
  96  *
  97  * Arguments:   @tunnel *t@ = pointer to tunnel block
  98  *              @peer *p@ = pointer to peer block
  99  *
 100  * Returns:     Zero if it worked, nonzero on failure.
 101  *
 102  * Use:         Initializes a new tunnel.
 103  */
 104
 105 int tun_create(tunnel *t, peer *p)
 106 {
 107   int fd;
 108   unsigned n;
 109   char buf[16];
 110
 111   n = 0;
 112   for (;;) {
 113     sprintf(buf, "/dev/tun%u", n);
 114     if ((fd = open(buf, O_RDWR)) >= 0)
 115       break;
 116     switch (errno) {
 117       case EBUSY:
 118         T( trace(T_TUNNEL, "tunnel device %u busy: skipping", n); )
 119         break;
 120       case ENOENT:
 121         a_warn("no suitable tunnel devices found");
 122         return (-1);
 123       default:
 124         a_warn("error opening `%s': %s (skipping)", buf, strerror(errno));
 125         break;
 126     }
 127     n++;
 128   }
 129
 130   fdflags(fd, O_NONBLOCK, O_NONBLOCK, FD_CLOEXEC, FD_CLOEXEC);
 131   t->p = p;
 132   t->n = n;
 133   sel_initfile(&sel, &t->f, fd, SEL_READ, t_read, t);
 134   sel_addfile(&t->f);
 135   T( trace(T_TUNNEL, "tunnel: attached interface %s to peer `%s'",
 136            tun_ifname(t), p_name(p)); )
 137   return (0);
 138 }
 139
 140 /* --- @tun_ifname@ --- *
 141  *
 142  * Arguments:   @tunnel *t@ = pointer to tunnel block
 143  *
 144  * Returns:     A pointer to the tunnel's interface name.
 145  */
 146
 147 const char *tun_ifname(tunnel *t)
 148 {
 149   static char buf[8];
 150   sprintf(buf, "tun%u", t->n);
 151   return (buf);
 152 }
 153
 154 /* --- @tun_inject@ --- *
 155  *
 156  * Arguments:   @tunnel *t@ = pointer to tunnel block
 157  *              @buf *b@ = buffer to send
 158  *
 159  * Returns:     ---
 160  *
 161  * Use:         Injects a packet into the local network stack.
 162  */
 163
 164 void tun_inject(tunnel *t, buf *b)
 165 {
 166   IF_TRACING(T_TUNNEL, {
 167     trace(T_TUNNEL, "tunnel: inject decrypted packet");
 168     trace_block(T_PACKET, "tunnel: packet contents", BBASE(b), BLEN(b));
 169   })
 170   write(t->f.fd, BBASE(b), BLEN(b));
 171 }
 172
 173 /* --- @tun_destroy@ --- *
 174  *
 175  * Arguments:   @tunnel *t@ = pointer to tunnel block
 176  *
 177  * Returns:     ---
 178  *
 179  * Use:         Destroys a tunnel.
 180  */
 181
 182 void tun_destroy(tunnel *t)
 183 {
 184   sel_rmfile(&t->f);
 185   close(t->f.fd);
 186 }
 187
 188 /*----- That's all, folks -------------------------------------------------*/