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analyse: critical bug in the counting code

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The problem is, that you simply count all lease occurrences in
dhcpd.leases, but only the last ones for each ip address are
valid.  The lease file is more like a logfile of what has been
done, than a real database.  To fix the counting issue, I'm using
a single hash (from uthash.h [1]) for the counting.  This way
only the last lease entry for each IP gets into my counting
structure.

When you remove the duplicates in prepare_data(), you don't have
the information anymore, if the active lease entry or the free
lease entry came last.  Simply deleting each ip from the touches
array, that is already in the leases array, gives you a big
chance to count wrong.  Another way of fixing this would be to
not only store the ips in your arrays, but a structure containing
the ip and a global lease entry counter.  Then you could delete
all entries except for the latest.

[1] http://uthash.sourceforge.net/

Reported-by: Huangy
Signed-off-by: Enno Grper <groepeen@cms.hu-berlin.de>
Signed-off-by: Sami Kerola <kerolasa@iki.fi>
This commit is contained in:
Enno Grper 2012-05-02 14:01:07 +02:00 • committed by Sami Kerola
parent 3ef5d6c07f
commit ae7747db87
10 changed files with 166 additions and 150 deletions
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80
src/hash.c Normal file
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/*
* The dhcpd-pools has BSD 2-clause license which also known as "Simplified
* BSD License" or "FreeBSD License".
*
* Copyright 2012- Enno Gröper. 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 AND CONTRIBUTORS ``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 AND CONTRIBUTORS OR
* CONTRIBUTORS 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.
*
* The views and conclusions contained in the software and documentation are
* those of the authors and should not be interpreted as representing
* official policies, either expressed or implied, of Sami Kerola.
*/
#include "dhcpd-pools.h"
void add_lease(int ip, enum ltype type)
{
struct leases_t *l;
l = safe_malloc(sizeof(struct leases_t));
l->ip = ip;
l->type = type;
HASH_ADD_INT(leases, ip, l);
}
struct leases_t *find_lease(int ip)
{
struct leases_t *l;
HASH_FIND_INT(leases, &ip, l);
return l;
}
void delete_lease(struct leases_t *lease)
{
HASH_DEL(leases, lease);
free(lease);
}
/* uthash >= 1.9.2
void delete_all_leases()
{
struct leases_t *l, *tmp;
HASH_ITER(hh, leases, l, tmp) {
HASH_DEL(leases, l);
free(l);
}
}
*/
void delete_all_leases()
{
struct leases_t *l;
while (leases) {
l = leases;
HASH_DEL(leases, l); /* leases advances to next on delete */
free(l);
}
}