/*      $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 */
}