/*  
 *  This file is free software: you may copy, redistribute and/or modify it  
 *  under the terms of the GNU General Public License as published by the  
 *  Free Software Foundation, either version 2 of the License, or (at your  
 *  option) any later version.  
 *  
 *  This file is distributed in the hope that it will be useful, but  
 *  WITHOUT ANY WARRANTY; without even the implied warranty of  
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU  
 *  General Public License for more details.  
 *  
 *  You should have received a copy of the GNU General Public License  
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.  
 *  
 * This file incorporates work covered by the following copyright and  
 * permission notice:  
 *  
Copyright (c) 2007, 2008 by Juliusz Chroboczek

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
*/

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <sys/time.h>

#include "babel_main.h"
#include "babeld.h"
#include "util.h"
#include "source.h"
#include "babel_interface.h"
#include "route.h"

struct source *srcs = NULL;

struct source*
find_source(const unsigned char *id, const unsigned char *p, unsigned char plen,
            int create, unsigned short seqno)
{
    struct source *src;

    for(src = srcs; src; src = src->next) {
        /* This should really be a hash table.  For now, check the
           last byte first. */
        if(src->id[7] != id[7])
            continue;
        if(memcmp(src->id, id, 8) != 0)
            continue;
        if(src->plen != plen)
            continue;
        if(memcmp(src->prefix, p, 16) == 0)
            return src;
    }

    if(!create)
        return NULL;

    src = malloc(sizeof(struct source));
    if(src == NULL) {
        zlog_err("malloc(source): %s", safe_strerror(errno));
        return NULL;
    }

    memcpy(src->id, id, 8);
    memcpy(src->prefix, p, 16);
    src->plen = plen;
    src->seqno = seqno;
    src->metric = INFINITY;
    src->time = babel_now.tv_sec;
    src->route_count = 0;
    src->next = srcs;
    srcs = src;
    return src;
}

struct source *
retain_source(struct source *src)
{
    assert(src->route_count < 0xffff);
    src->route_count++;
    return src;
}

void
release_source(struct source *src)
{
    assert(src->route_count > 0);
    src->route_count--;
}

int
flush_source(struct source *src)
{
    if(src->route_count > 0)
        /* The source is in use by a route. */
        return 0;

    if(srcs == src) {
        srcs = src->next;
    } else {
        struct source *previous = srcs;
        while(previous->next != src)
            previous = previous->next;
        previous->next = src->next;
    }

    free(src);
    return 1;
}

void
update_source(struct source *src,
              unsigned short seqno, unsigned short metric)
{
    if(metric >= INFINITY)
        return;

    /* If a source is expired, pretend that it doesn't exist and update
       it unconditionally.  This makes ensures that old data will
       eventually be overridden, and prevents us from getting stuck if
       a router loses its sequence number. */
    if(src->time < babel_now.tv_sec - SOURCE_GC_TIME ||
       seqno_compare(src->seqno, seqno) < 0 ||
       (src->seqno == seqno && src->metric > metric)) {
        src->seqno = seqno;
        src->metric = metric;
    }
    src->time = babel_now.tv_sec;
}

void
expire_sources()
{
    struct source *src;

    src = srcs;
    while(src) {
        if(src->time > babel_now.tv_sec)
            /* clock stepped */
            src->time = babel_now.tv_sec;
        if(src->time < babel_now.tv_sec - SOURCE_GC_TIME) {
            struct source *old = src;
            src = src->next;
            flush_source(old);
            continue;
        }
        src = src->next;
    }
}

void
check_sources_released(void)
{
    struct source *src;

    for(src = srcs; src; src = src->next) {
        if(src->route_count != 0)
            fprintf(stderr, "Warning: source %s %s has refcount %d.\n",
                    format_eui64(src->id),
                    format_prefix(src->prefix, src->plen),
                    (int)src->route_count);
    }
}