freebsd-dev/usr.sbin/pkg/dns_utils.c
Xin LI f595a30ba0 Plug a possible memory leak.
MFC after:	2 weeks
2015-08-27 06:28:42 +00:00

223 lines
4.9 KiB
C

/*-
* Copyright (c) 2012-2013 Baptiste Daroussin <bapt@FreeBSD.org>
* 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,
* without modification, immediately at the beginning of the file.
* 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>
__FBSDID("$FreeBSD$");
#include <stdlib.h>
#include <string.h>
#include <netinet/in.h>
#include <resolv.h>
#include "dns_utils.h"
typedef union {
HEADER hdr;
unsigned char buf[1024];
} dns_query;
static int
srv_priority_cmp(const void *a, const void *b)
{
const struct dns_srvinfo *da, *db;
unsigned int r, l;
da = *(struct dns_srvinfo * const *)a;
db = *(struct dns_srvinfo * const *)b;
l = da->priority;
r = db->priority;
return ((l > r) - (l < r));
}
static int
srv_final_cmp(const void *a, const void *b)
{
const struct dns_srvinfo *da, *db;
unsigned int r, l, wr, wl;
int res;
da = *(struct dns_srvinfo * const *)a;
db = *(struct dns_srvinfo * const *)b;
l = da->priority;
r = db->priority;
res = ((l > r) - (l < r));
if (res == 0) {
wl = da->finalweight;
wr = db->finalweight;
res = ((wr > wl) - (wr < wl));
}
return (res);
}
static void
compute_weight(struct dns_srvinfo **d, int first, int last)
{
int i, j, totalweight;
int *chosen;
totalweight = 0;
for (i = 0; i <= last; i++)
totalweight += d[i]->weight;
if (totalweight == 0)
return;
chosen = malloc(sizeof(int) * (last - first + 1));
for (i = 0; i <= last; i++) {
for (;;) {
chosen[i] = random() % (d[i]->weight * 100 / totalweight);
for (j = 0; j < i; j++) {
if (chosen[i] == chosen[j])
break;
}
if (j == i) {
d[i]->finalweight = chosen[i];
break;
}
}
}
free(chosen);
}
struct dns_srvinfo *
dns_getsrvinfo(const char *zone)
{
struct dns_srvinfo **res, *first;
unsigned char *end, *p;
char host[MAXHOSTNAMELEN];
dns_query q;
int len, qdcount, ancount, n, i, f, l;
unsigned int type, class, ttl, priority, weight, port;
if ((len = res_query(zone, C_IN, T_SRV, q.buf, sizeof(q.buf))) == -1 ||
len < (int)sizeof(HEADER))
return (NULL);
qdcount = ntohs(q.hdr.qdcount);
ancount = ntohs(q.hdr.ancount);
end = q.buf + len;
p = q.buf + sizeof(HEADER);
while(qdcount > 0 && p < end) {
qdcount--;
if((len = dn_expand(q.buf, end, p, host, MAXHOSTNAMELEN)) < 0)
return (NULL);
p += len + NS_QFIXEDSZ;
}
res = calloc(ancount, sizeof(struct dns_srvinfo *));
if (res == NULL)
return (NULL);
n = 0;
while (ancount > 0 && p < end) {
ancount--;
len = dn_expand(q.buf, end, p, host, MAXHOSTNAMELEN);
if (len < 0) {
for (i = 0; i < n; i++)
free(res[i]);
free(res);
return NULL;
}
p += len;
NS_GET16(type, p);
NS_GET16(class, p);
NS_GET32(ttl, p);
NS_GET16(len, p);
if (type != T_SRV) {
p += len;
continue;
}
NS_GET16(priority, p);
NS_GET16(weight, p);
NS_GET16(port, p);
len = dn_expand(q.buf, end, p, host, MAXHOSTNAMELEN);
if (len < 0) {
for (i = 0; i < n; i++)
free(res[i]);
free(res);
return (NULL);
}
res[n] = malloc(sizeof(struct dns_srvinfo));
if (res[n] == NULL) {
for (i = 0; i < n; i++)
free(res[i]);
free(res);
return (NULL);
}
res[n]->type = type;
res[n]->class = class;
res[n]->ttl = ttl;
res[n]->priority = priority;
res[n]->weight = weight;
res[n]->port = port;
res[n]->next = NULL;
strlcpy(res[n]->host, host, MAXHOSTNAMELEN);
p += len;
n++;
}
qsort(res, n, sizeof(res[0]), srv_priority_cmp);
priority = f = l = 0;
for (i = 0; i < n; i++) {
if (res[i]->priority != priority) {
if (f != l)
compute_weight(res, f, l);
f = i;
priority = res[i]->priority;
}
l = i;
}
qsort(res, n, sizeof(res[0]), srv_final_cmp);
for (i = 0; i < n - 1; i++)
res[i]->next = res[i + 1];
first = res[0];
free(res);
return (first);
}