/*      $NetBSD: tap.c,v 1.5 2009/05/12 21:21:23 plunky Exp $   */

/*-
* Copyright (c) 2008 Iain Hibbert
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in the
*    documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

#include <sys/cdefs.h>
__RCSID("$NetBSD: tap.c,v 1.5 2009/05/12 21:21:23 plunky Exp $");

#include <sys/ioctl.h>
#include <sys/uio.h>

#include <net/if_dl.h>
#include <net/if_tap.h>

#include <fcntl.h>
#include <unistd.h>
#include <util.h>

#include "btpand.h"

static void tap_exit(void);
static bool tap_send(channel_t *, packet_t *);
static bool tap_recv(packet_t *);
static void tap_down(channel_t *);

void
tap_init(void)
{
       channel_t *chan;
       struct sockaddr_dl *sdl;
       struct if_laddrreq iflr;
       struct ifreq ifr;
       int fd, s;

       fd = open(interface_name, O_RDWR);
       if (fd == -1) {
               log_err("Could not open \"%s\": %m", interface_name);
               exit(EXIT_FAILURE);
       }

       memset(&ifr, 0, sizeof(ifr));
       if (ioctl(fd, TAPGIFNAME, &ifr) == -1) {
               log_err("Could not get interface name: %m");
               exit(EXIT_FAILURE);
       }
       interface_name = strndup(ifr.ifr_name, IFNAMSIZ);
       atexit(tap_exit);

       s = socket(PF_LINK, SOCK_DGRAM, 0);
       if (s == -1) {
               log_err("Could not open PF_LINK socket: %m");
               exit(EXIT_FAILURE);
       }

       memset(&iflr, 0, sizeof(iflr));
       memcpy(iflr.iflr_name, ifr.ifr_name, IFNAMSIZ);
       iflr.flags = IFLR_ACTIVE;

       sdl = satosdl(sstosa(&iflr.addr));
       sdl->sdl_family = AF_LINK;
       sdl->sdl_len = sizeof(struct sockaddr_dl);
       sdl->sdl_alen = ETHER_ADDR_LEN;
       b2eaddr(LLADDR(sdl), &local_bdaddr);

       if (ioctl(s, SIOCALIFADDR, &iflr) == -1) {
               log_err("Could not add %s link address: %m", iflr.iflr_name);
               exit(EXIT_FAILURE);
       }

       if (ioctl(s, SIOCGIFFLAGS, &ifr) == -1) {
               log_err("Could not get interface flags: %m");
               exit(EXIT_FAILURE);
       }

       if ((ifr.ifr_flags & IFF_UP) == 0) {
               ifr.ifr_flags |= IFF_UP;

               if (ioctl(s, SIOCSIFFLAGS, &ifr) == -1) {
                       log_err("Could not set IFF_UP: %m");
                       exit(EXIT_FAILURE);
               }
       }

       close(s);

       log_info("Using interface %s with addr %s",
           ifr.ifr_name, ether_ntoa((struct ether_addr *)LLADDR(sdl)));

       chan = channel_alloc();
       if (chan == NULL)
               exit(EXIT_FAILURE);

       chan->send = tap_send;
       chan->recv = tap_recv;
       chan->down = tap_down;
       chan->mru = ETHER_HDR_LEN + ETHER_MAX_LEN;
       memcpy(chan->raddr, LLADDR(sdl), ETHER_ADDR_LEN);
       memcpy(chan->laddr, LLADDR(sdl), ETHER_ADDR_LEN);
       chan->state = CHANNEL_OPEN;
       if (!channel_open(chan, fd))
               exit(EXIT_FAILURE);

       if (pidfile(ifr.ifr_name) == -1)
               log_err("pidfile not made");
}

static void
tap_exit(void)
{
       struct ifreq ifr;
       int s;

       s = socket(PF_LINK, SOCK_DGRAM, 0);
       if (s == -1) {
               log_err("Could not open PF_LINK socket: %m");
               return;
       }

       strncpy(ifr.ifr_name, interface_name, IFNAMSIZ);
       if (ioctl(s, SIOCGIFFLAGS, &ifr) == -1) {
               log_err("Could not get interface flags: %m");
               return;
       }

       if ((ifr.ifr_flags & IFF_UP)) {
               ifr.ifr_flags &= ~IFF_UP;
               if (ioctl(s, SIOCSIFFLAGS, &ifr) == -1) {
                       log_err("Could not clear IFF_UP: %m");
                       return;
               }
       }

       close(s);
}

static bool
tap_send(channel_t *chan, packet_t *pkt)
{
       struct iovec iov[4];
       ssize_t nw;

       iov[0].iov_base = pkt->dst;
       iov[0].iov_len = ETHER_ADDR_LEN;
       iov[1].iov_base = pkt->src;
       iov[1].iov_len = ETHER_ADDR_LEN;
       iov[2].iov_base = pkt->type;
       iov[2].iov_len = ETHER_TYPE_LEN;
       iov[3].iov_base = pkt->ptr;
       iov[3].iov_len = pkt->len;

       /* tap device write never fails */
       nw = writev(chan->fd, iov, __arraycount(iov));
       assert(nw > 0);

       return true;
}

static bool
tap_recv(packet_t *pkt)
{

       if (pkt->len < ETHER_HDR_LEN)
               return false;

       pkt->dst = pkt->ptr;
       packet_adj(pkt, ETHER_ADDR_LEN);
       pkt->src = pkt->ptr;
       packet_adj(pkt, ETHER_ADDR_LEN);
       pkt->type = pkt->ptr;
       packet_adj(pkt, ETHER_TYPE_LEN);

       return true;
}

static void
tap_down(channel_t *chan)
{

       /* we never close the tap channel */
}