/*      $NetBSD: channel.c,v 1.4 2011/01/27 11:13:59 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: channel.c,v 1.4 2011/01/27 11:13:59 plunky Exp $");

#include <sys/ioctl.h>

#include <unistd.h>

#include "btpand.h"

static struct chlist    channel_list;
static int              channel_tick;

static void channel_start(int, short, void *);
static void channel_read(int, short, void *);
static void channel_dispatch(packet_t *);
static void channel_watchdog(int, short, void *);

void
channel_init(void)
{

       LIST_INIT(&channel_list);
}

channel_t *
channel_alloc(void)
{
       channel_t *chan;

       chan = malloc(sizeof(channel_t));
       if (chan == NULL) {
               log_err("%s() failed: %m", __func__);
               return NULL;
       }

       memset(chan, 0, sizeof(channel_t));
       STAILQ_INIT(&chan->pktlist);
       chan->state = CHANNEL_CLOSED;
       LIST_INSERT_HEAD(&channel_list, chan, next);

       return chan;
}

bool
channel_open(channel_t *chan, int fd)
{
       int n;

       assert(chan->refcnt == 0);
       assert(chan->state != CHANNEL_CLOSED);
       assert(chan->send != NULL);
       assert(chan->recv != NULL);
       assert(chan->down != NULL);

       if (chan->mtu > 0) {
               chan->sendbuf = malloc(chan->mtu);
               if (chan->sendbuf == NULL) {
                       log_err("Could not malloc channel sendbuf: %m");
                       return false;
               }
       }

       n = 1;
       if (ioctl(fd, FIONBIO, &n) == -1) {
               log_err("Could not set non-blocking IO: %m");
               return false;
       }

       event_set(&chan->rd_ev, fd, EV_READ | EV_PERSIST, channel_read, chan);
       if (event_add(&chan->rd_ev, NULL) == -1) {
               log_err("Could not add channel read event: %m");
               return false;
       }

       event_set(&chan->wr_ev, fd, EV_WRITE, channel_start, chan);

       chan->refcnt++;
       chan->fd = fd;

       log_debug("(fd#%d)", chan->fd);

       return true;
}

void
channel_close(channel_t *chan)
{
       pkthdr_t *ph;

       assert(chan->state != CHANNEL_CLOSED);

       log_debug("(fd#%d)", chan->fd);

       chan->state = CHANNEL_CLOSED;
       event_del(&chan->rd_ev);
       event_del(&chan->wr_ev);
       close(chan->fd);
       chan->refcnt--;
       chan->tick = 0;

       while ((ph = STAILQ_FIRST(&chan->pktlist)) != NULL) {
               STAILQ_REMOVE_HEAD(&chan->pktlist, next);
               pkthdr_free(ph);
               chan->qlen--;
       }

       if (chan->refcnt == 0)
               channel_free(chan);
}

void
channel_free(channel_t *chan)
{

       assert(chan->refcnt == 0);
       assert(chan->state == CHANNEL_CLOSED);
       assert(chan->qlen == 0);
       assert(STAILQ_EMPTY(&chan->pktlist));

       LIST_REMOVE(chan, next);
       free(chan->pfilter);
       free(chan->mfilter);
       free(chan->sendbuf);
       free(chan);
}

static void
channel_start(int fd, short ev, void *arg)
{
       channel_t *chan = arg;
       pkthdr_t *ph;

       chan->oactive = true;

       while (chan->qlen > 0) {
               ph = STAILQ_FIRST(&chan->pktlist);

               channel_timeout(chan, 10);
               if (chan->send(chan, ph->data) == false) {
                       if (event_add(&chan->wr_ev, NULL) == -1) {
                               log_err("Could not add channel write event: %m");
                               chan->down(chan);
                       }
                       return;
               }

               STAILQ_REMOVE_HEAD(&chan->pktlist, next);
               pkthdr_free(ph);
               chan->qlen--;
       }

       channel_timeout(chan, 0);
       chan->oactive = false;
}

static void
channel_read(int fd, short ev, void *arg)
{
       channel_t *chan = arg;
       packet_t *pkt;
       ssize_t nr;

       pkt = packet_alloc(chan);
       if (pkt == NULL) {
               chan->down(chan);
               return;
       }

       nr = read(fd, pkt->buf, chan->mru);
       if (nr == -1) {
               log_err("channel read error: %m");
               packet_free(pkt);
               chan->down(chan);
               return;
       }
       if (nr == 0) {  /* EOF */
               log_debug("(fd#%d) EOF", fd);
               packet_free(pkt);
               chan->down(chan);
               return;
       }
       pkt->len = nr;

       if (chan->recv(pkt) == true)
               channel_dispatch(pkt);

       packet_free(pkt);
}

static void
channel_dispatch(packet_t *pkt)
{
       channel_t *chan;

       /*
        * This is simple routing. I'm not sure if its allowed by
        * the PAN or BNEP specifications, but it seems logical
        * to send unicast packets to connected destinations where
        * possible.
        */
       if (!ETHER_IS_MULTICAST(pkt->dst)) {
               LIST_FOREACH(chan, &channel_list, next) {
                       if (chan == pkt->chan
                           || chan->state != CHANNEL_OPEN)
                               continue;

                       if (memcmp(pkt->dst, chan->raddr, ETHER_ADDR_LEN) == 0) {
                               if (chan->qlen > CHANNEL_MAXQLEN)
                                       log_notice("Queue overflow");
                               else
                                       channel_put(chan, pkt);

                               return;
                       }
               }
       }

       LIST_FOREACH(chan, &channel_list, next) {
               if (chan == pkt->chan
                   || chan->state != CHANNEL_OPEN)
                       continue;

               if (chan->qlen > CHANNEL_MAXQLEN) {
                       log_notice("Queue overflow");
                       continue;
               }

               channel_put(chan, pkt);
       }
}

void
channel_put(channel_t *chan, packet_t *pkt)
{
       pkthdr_t *ph;

       ph = pkthdr_alloc(pkt);
       if (ph == NULL)
               return;

       chan->qlen++;
       STAILQ_INSERT_TAIL(&chan->pktlist, ph, next);

       if (!chan->oactive)
               channel_start(chan->fd, EV_WRITE, chan);
}

/*
* Simple watchdog timer, only ticks when it is required and
* closes the channel down if it times out.
*/
void
channel_timeout(channel_t *chan, int to)
{
       static struct event ev;

       if (to == 0)
               chan->tick = 0;
       else
               chan->tick = (channel_tick + to) % 60;

       if (channel_tick == 0) {
               evtimer_set(&ev, channel_watchdog, &ev);
               channel_watchdog(0, 0, &ev);
       }
}

static void
channel_watchdog(int fd, short ev, void *arg)
{
       static struct timeval tv = { .tv_sec = 1 };
       channel_t *chan, *next;
       int tick;

       tick = (channel_tick % 60) + 1;
       channel_tick = 0;

       next = LIST_FIRST(&channel_list);
       while ((chan = next) != NULL) {
               next = LIST_NEXT(chan, next);

               if (chan->tick == tick)
                       chan->down(chan);
               else if (chan->tick != 0)
                       channel_tick = tick;
       }

       if (channel_tick != 0 && evtimer_add(arg, &tv) == -1) {
               log_err("Could not add watchdog event: %m");
               exit(EXIT_FAILURE);
       }
}

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