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tap.c revision 1.2 
      1 /*	$NetBSD: tap.c,v 1.2 2009/03/10 22:12:17 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 1.2 2009/03/10 22:12:17 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 bool tap_send(channel_t *, packet_t *);
     44 static bool tap_recv(packet_t *);
     45 
     46 void
     47 tap_init(void)
     48 {
     49 	channel_t *chan;
     50 	struct sockaddr_dl *sdl;
     51 	struct if_laddrreq iflr;
     52 	struct ifreq ifr;
     53 	int fd, s;
     54 
     55 	fd = open(interface_name, O_RDWR);
     56 	if (fd == -1) {
     57 		log_err("Could not open \"%s\": %m", interface_name);
     58 		exit(EXIT_FAILURE);
     59 	}
     60 
     61 	memset(&ifr, 0, sizeof(ifr));
     62 	if (ioctl(fd, TAPGIFNAME, &ifr) == -1) {
     63 		log_err("Could not get interface name: %m");
     64 		exit(EXIT_FAILURE);
     65 	}
     66 
     67 	s = socket(PF_LINK, SOCK_DGRAM, 0);
     68 	if (s == -1) {
     69 		log_err("Could not open PF_LINK socket: %m");
     70 		exit(EXIT_FAILURE);
     71 	}
     72 
     73 	memset(&iflr, 0, sizeof(iflr));
     74 	memcpy(iflr.iflr_name, ifr.ifr_name, IFNAMSIZ);
     75 	iflr.flags = IFLR_ACTIVE;
     76 
     77 	sdl = satosdl(sstosa(&iflr.addr));
     78 	sdl->sdl_family = AF_LINK;
     79 	sdl->sdl_len = sizeof(struct sockaddr_dl);
     80 	sdl->sdl_alen = ETHER_ADDR_LEN;
     81 	b2eaddr(LLADDR(sdl), &local_bdaddr);
     82 
     83 	if (ioctl(s, SIOCALIFADDR, &iflr) == -1) {
     84 		log_err("Could not add %s link address: %m", iflr.iflr_name);
     85 		exit(EXIT_FAILURE);
     86 	}
     87 
     88 	if (ioctl(s, SIOCGIFFLAGS, &ifr) == -1) {
     89 		log_err("Could not get interface flags: %m");
     90 		exit(EXIT_FAILURE);
     91 	}
     92 
     93 	if ((ifr.ifr_flags & IFF_UP) == 0) {
     94 		ifr.ifr_flags |= IFF_UP;
     95 
     96 		if (ioctl(s, SIOCSIFFLAGS, &ifr) == -1) {
     97 			log_err("Could not set IFF_UP: %m");
     98 			exit(EXIT_FAILURE);
     99 		}
    100 	}
    101 
    102 	close(s);
    103 
    104 	log_info("Using interface %s with addr %s",
    105 	    ifr.ifr_name, ether_ntoa((struct ether_addr *)LLADDR(sdl)));
    106 
    107 	chan = channel_alloc();
    108 	if (chan == NULL)
    109 		exit(EXIT_FAILURE);
    110 
    111 	chan->send = tap_send;
    112 	chan->recv = tap_recv;
    113 	chan->mru = ETHER_HDR_LEN + ETHER_MAX_LEN;
    114 	memcpy(chan->raddr, LLADDR(sdl), ETHER_ADDR_LEN);
    115 	memcpy(chan->laddr, LLADDR(sdl), ETHER_ADDR_LEN);
    116 	chan->state = CHANNEL_OPEN;
    117 	if (!channel_open(chan, fd))
    118 		exit(EXIT_FAILURE);
    119 
    120 	if (pidfile(ifr.ifr_name) == -1)
    121 		log_err("pidfile not made");
    122 }
    123 
    124 static bool
    125 tap_send(channel_t *chan, packet_t *pkt)
    126 {
    127 	struct iovec iov[4];
    128 	ssize_t nw;
    129 
    130 	iov[0].iov_base = pkt->dst;
    131 	iov[0].iov_len = ETHER_ADDR_LEN;
    132 	iov[1].iov_base = pkt->src;
    133 	iov[1].iov_len = ETHER_ADDR_LEN;
    134 	iov[2].iov_base = pkt->type;
    135 	iov[2].iov_len = ETHER_TYPE_LEN;
    136 	iov[3].iov_base = pkt->ptr;
    137 	iov[3].iov_len = pkt->len;
    138 
    139 	/* tap device write never fails */
    140 	nw = writev(chan->fd, iov, __arraycount(iov));
    141 	_DIAGASSERT(nw > 0);
    142 
    143 	return true;
    144 }
    145 
    146 static bool
    147 tap_recv(packet_t *pkt)
    148 {
    149 
    150 	if (pkt->len < ETHER_HDR_LEN)
    151 		return false;
    152 
    153 	pkt->dst = pkt->ptr;
    154 	packet_adj(pkt, ETHER_ADDR_LEN);
    155 	pkt->src = pkt->ptr;
    156 	packet_adj(pkt, ETHER_ADDR_LEN);
    157 	pkt->type = pkt->ptr;
    158 	packet_adj(pkt, ETHER_TYPE_LEN);
    159 
    160 	return true;
    161 }
    162