usr.sbin/btpand/tap.c

   1 /*      $NetBSD: tap.c,v 1.4 2009/05/12 21:08:30 plunky Exp $   */
   2
   3 /*-
   4  * Copyright (c) 2008 Iain Hibbert
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  17  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  18  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  19  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  20  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  21  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  22  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  23  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  24  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  25  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  26  */
  27
  28 #include <sys/cdefs.h>
  29 __RCSID("$NetBSD: tap.c,v 1.4 2009/05/12 21:08:30 plunky Exp $");
  30
  31 #include <sys/ioctl.h>
  32 #include <sys/uio.h>
  33
  34 #include <net/if_dl.h>
  35 #include <net/if_tap.h>
  36
  37 #include <fcntl.h>
  38 #include <unistd.h>
  39 #include <util.h>
  40
  41 #include "btpand.h"
  42
  43 static void tap_exit(void);
  44 static bool tap_send(channel_t *, packet_t *);
  45 static bool tap_recv(packet_t *);
  46 static void tap_down(channel_t *);
  47
  48 void
  49 tap_init(void)
  50 {
  51         channel_t *chan;
  52         struct sockaddr_dl *sdl;
  53         struct if_laddrreq iflr;
  54         struct ifreq ifr;
  55         int fd, s;
  56
  57         fd = open(interface_name, O_RDWR);
  58         if (fd == -1) {
  59                 log_err("Could not open \"%s\": %m", interface_name);
  60                 exit(EXIT_FAILURE);
  61         }
  62
  63         memset(&ifr, 0, sizeof(ifr));
  64         if (ioctl(fd, TAPGIFNAME, &ifr) == -1) {
  65                 log_err("Could not get interface name: %m");
  66                 exit(EXIT_FAILURE);
  67         }
  68         interface_name = strndup(ifr.ifr_name, IFNAMSIZ);
  69         atexit(tap_exit);
  70
  71         s = socket(PF_LINK, SOCK_DGRAM, 0);
  72         if (s == -1) {
  73                 log_err("Could not open PF_LINK socket: %m");
  74                 exit(EXIT_FAILURE);
  75         }
  76
  77         memset(&iflr, 0, sizeof(iflr));
  78         memcpy(iflr.iflr_name, ifr.ifr_name, IFNAMSIZ);
  79         iflr.flags = IFLR_ACTIVE;
  80
  81         sdl = satosdl(sstosa(&iflr.addr));
  82         sdl->sdl_family = AF_LINK;
  83         sdl->sdl_len = sizeof(struct sockaddr_dl);
  84         sdl->sdl_alen = ETHER_ADDR_LEN;
  85         b2eaddr(LLADDR(sdl), &local_bdaddr);
  86
  87         if (ioctl(s, SIOCALIFADDR, &iflr) == -1) {
  88                 log_err("Could not add %s link address: %m", iflr.iflr_name);
  89                 exit(EXIT_FAILURE);
  90         }
  91
  92         if (ioctl(s, SIOCGIFFLAGS, &ifr) == -1) {
  93                 log_err("Could not get interface flags: %m");
  94                 exit(EXIT_FAILURE);
  95         }
  96
  97         if ((ifr.ifr_flags & IFF_UP) == 0) {
  98                 ifr.ifr_flags |= IFF_UP;
  99
 100                 if (ioctl(s, SIOCSIFFLAGS, &ifr) == -1) {
 101                         log_err("Could not set IFF_UP: %m");
 102                         exit(EXIT_FAILURE);
 103                 }
 104         }
 105
 106         close(s);
 107
 108         log_info("Using interface %s with addr %s",
 109             ifr.ifr_name, ether_ntoa((struct ether_addr *)LLADDR(sdl)));
 110
 111         chan = channel_alloc();
 112         if (chan == NULL)
 113                 exit(EXIT_FAILURE);
 114
 115         chan->send = tap_send;
 116         chan->recv = tap_recv;
 117         chan->down = tap_down;
 118         chan->mru = ETHER_HDR_LEN + ETHER_MAX_LEN;
 119         memcpy(chan->raddr, LLADDR(sdl), ETHER_ADDR_LEN);
 120         memcpy(chan->laddr, LLADDR(sdl), ETHER_ADDR_LEN);
 121         chan->state = CHANNEL_OPEN;
 122         if (!channel_open(chan, fd))
 123                 exit(EXIT_FAILURE);
 124
 125         if (pidfile(ifr.ifr_name) == -1)
 126                 log_err("pidfile not made");
 127 }
 128
 129 static void
 130 tap_exit(void)
 131 {
 132         struct ifreq ifr;
 133         int s;
 134
 135         s = socket(PF_LINK, SOCK_DGRAM, 0);
 136         if (s == -1) {
 137                 log_err("Could not open PF_LINK socket: %m");
 138                 return;
 139         }
 140
 141         strncpy(ifr.ifr_name, interface_name, IFNAMSIZ);
 142         if (ioctl(s, SIOCGIFFLAGS, &ifr) == -1) {
 143                 log_err("Could not get interface flags: %m");
 144                 return;
 145         }
 146
 147         if ((ifr.ifr_flags & IFF_UP)) {
 148                 ifr.ifr_flags &= ~IFF_UP;
 149                 if (ioctl(s, SIOCSIFFLAGS, &ifr) == -1) {
 150                         log_err("Could not clear IFF_UP: %m");
 151                         return;
 152                 }
 153         }
 154
 155         close(s);
 156 }
 157
 158 static bool
 159 tap_send(channel_t *chan, packet_t *pkt)
 160 {
 161         struct iovec iov[4];
 162         ssize_t nw;
 163
 164         iov[0].iov_base = pkt->dst;
 165         iov[0].iov_len = ETHER_ADDR_LEN;
 166         iov[1].iov_base = pkt->src;
 167         iov[1].iov_len = ETHER_ADDR_LEN;
 168         iov[2].iov_base = pkt->type;
 169         iov[2].iov_len = ETHER_TYPE_LEN;
 170         iov[3].iov_base = pkt->ptr;
 171         iov[3].iov_len = pkt->len;
 172
 173         /* tap device write never fails */
 174         nw = writev(chan->fd, iov, __arraycount(iov));
 175         assert(nw > 0);
 176
 177         return true;
 178 }
 179
 180 static bool
 181 tap_recv(packet_t *pkt)
 182 {
 183
 184         if (pkt->len < ETHER_HDR_LEN)
 185                 return false;
 186
 187         pkt->dst = pkt->ptr;
 188         packet_adj(pkt, ETHER_ADDR_LEN);
 189         pkt->src = pkt->ptr;
 190         packet_adj(pkt, ETHER_ADDR_LEN);
 191         pkt->type = pkt->ptr;
 192         packet_adj(pkt, ETHER_TYPE_LEN);
 193
 194         return true;
 195 }
 196
 197 static void
 198 tap_down(channel_t *chan)
 199 {
 200
 201         /* we never close the tap channel */
 202 }