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resolve.c
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resolve.c
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/*
* Copyright (c) 1995, 1996, 1997 Kungliga Tekniska Hvgskolan
* (Royal Institute of Technology, Stockholm, Sweden).
* 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.
*
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the Kungliga Tekniska
* Hvgskolan and its contributors.
*
* 4. Neither the name of the Institute nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE 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 INSTITUTE 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.
*/
#include "config.h"
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/nameser.h>
#ifdef HAVE_ARPA_NAMESER_COMPAT_H
#include <arpa/nameser_compat.h>
#endif
#include <string.h>
#ifdef HAVE_STRINGS_H
#include <strings.h>
#endif
#include <resolv.h>
#include "resolve.h"
static char rcsId[] = "$Id: resolve.c,v 2.11 2009/05/26 07:25:12 lukeh Exp $";
#if defined(HAVE_RES_SEARCH) && defined(HAVE_DN_EXPAND)
#define DECL(X) {#X, T_##X}
static struct stot
{
char *name;
int type;
}
stot[] =
{
DECL (A),
DECL (NS),
DECL (CNAME), DECL (PTR), DECL (MX), DECL (TXT), DECL (AFSDB), DECL (SRV),
{
NULL, 0}
};
static int
string_to_type (const char *name)
{
struct stot *p = stot;
for (p = stot; p->name; p++)
if (strcasecmp (name, p->name) == 0)
return p->type;
return -1;
}
#if 0
static char *
type_to_string (int type)
{
struct stot *p = stot;
for (p = stot; p->name; p++)
if (type == p->type)
return p->name;
return NULL;
}
#endif
void
dns_free_data (struct dns_reply *r)
{
struct resource_record *rr;
if (r->q.domain)
free (r->q.domain);
for (rr = r->head; rr;)
{
struct resource_record *tmp = rr;
if (rr->domain)
free (rr->domain);
if (rr->u.data)
free (rr->u.data);
rr = rr->next;
free (tmp);
}
free (r);
}
static struct dns_reply *
parse_reply (unsigned char *data, int len)
{
unsigned char *p;
char host[128];
int status;
int query, response;
struct dns_reply *r;
struct resource_record **rr;
r = (struct dns_reply *) malloc (sizeof (struct dns_reply));
memset (r, 0, sizeof (struct dns_reply));
r->q.domain = NULL;
p = data;
memcpy (&r->h, p, sizeof (HEADER));
p += sizeof (HEADER);
for (query = 0; query < ntohs(r->h.qdcount); query++)
{
status = dn_expand (data, data + len, p, host, sizeof (host));
if (status < 0)
{
dns_free_data (r);
return NULL;
}
p += status;
if (p + 4 > data + len)
{
dns_free_data (r);
return NULL;
}
if (r->q.domain == NULL)
{
r->q.domain = strdup (host);
r->q.type = (p[0] << 8 | p[1]);
r->q.class = (p[2] << 8 | p[3]);
}
p += 4;
}
rr = &r->head;
for (response = 0; (response < ntohs(r->h.ancount)) && (p < data + len); response++)
{
unsigned int type, class, ttl, size;
status = dn_expand (data, data + len, p, host, sizeof (host));
if (status < 0)
{
dns_free_data (r);
return NULL;
}
p += status;
if (p + 10 > data + len)
{
dns_free_data (r);
return NULL;
}
type = (p[0] << 8) | p[1];
p += 2;
class = (p[0] << 8) | p[1];
p += 2;
ttl = (p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3];
p += 4;
size = (p[0] << 8) | p[1];
p += 2;
if (p + size > data + len)
{
dns_free_data (r);
return NULL;
}
*rr = (struct resource_record *) calloc (1,
sizeof (struct
resource_record));
(*rr)->domain = strdup (host);
(*rr)->type = type;
(*rr)->class = class;
(*rr)->ttl = ttl;
(*rr)->size = size;
switch (type)
{
case T_NS:
case T_CNAME:
case T_PTR:
status = dn_expand (data, data + len, p, host, sizeof (host));
if (status < 0)
{
dns_free_data (r);
return NULL;
}
(*rr)->u.txt = strdup (host);
break;
case T_MX:
case T_AFSDB:
{
if (p + 2 > data + len)
{
dns_free_data (r);
return NULL;
}
status = dn_expand (data, data + len, p + 2, host, sizeof (host));
if (status < 0)
{
dns_free_data (r);
return NULL;
}
(*rr)->u.mx =
(struct mx_record *) malloc (sizeof (struct mx_record) +
strlen (host));
(*rr)->u.mx->preference = (p[0] << 8) | p[1];
strcpy ((*rr)->u.mx->domain, host);
break;
}
case T_SRV:
{
if (p + 6 > data + len)
{
dns_free_data (r);
return NULL;
}
status = dn_expand (data, data + len, p + 6, host, sizeof (host));
if (status < 0)
{
dns_free_data (r);
return NULL;
}
(*rr)->u.srv =
(struct srv_record *) malloc (sizeof (struct srv_record) +
strlen (host));
(*rr)->u.srv->priority = (p[0] << 8) | p[1];
(*rr)->u.srv->weight = (p[2] << 8) | p[3];
(*rr)->u.srv->port = (p[4] << 8) | p[5];
strcpy ((*rr)->u.srv->target, host);
break;
}
case T_TXT:
{
if (p + *p > data + len)
{
dns_free_data (r);
return NULL;
}
(*rr)->u.txt = (char *) malloc (size + 1);
strncpy ((*rr)->u.txt, (char *) p + 1, *p);
(*rr)->u.txt[*p] = 0;
break;
}
default:
(*rr)->u.data = (unsigned char *) malloc (size);
memcpy ((*rr)->u.data, p, size);
}
p += size;
rr = &(*rr)->next;
}
*rr = NULL;
return r;
}
struct dns_reply *
dns_lookup (const char *domain, const char *type_name)
{
unsigned char *reply = NULL;
int len, rlen;
int type;
struct dns_reply *r = NULL;
type = string_to_type (type_name);
rlen = 1024;
reply = malloc(rlen);
do
{
len = res_search (domain, C_IN, type, reply, rlen);
if ((len == -1) || (len < rlen))
{
break;
}
reply = realloc (reply, len + 1024);
rlen = len + 1024;
}
while (1);
if (len >= 0)
r = parse_reply (reply, len);
free(reply);
return r;
}
#else /* defined(HAVE_RES_SEARCH) && defined(HAVE_DN_EXPAND) */
struct dns_reply *
dns_lookup (const char *domain, const char *type_name)
{
return NULL;
}
void
dns_free_data (struct dns_reply *r)
{
}
#endif
#ifdef TEST
int
main (int argc, char **argv)
{
struct dns_reply *r;
struct resource_record *rr;
r = dns_lookup (argv[1], argv[2]);
if (r == NULL)
{
printf ("No reply.\n");
return 1;
}
for (rr = r->head; rr; rr = rr->next)
{
printf ("%s %s %d ", rr->domain, type_to_string (rr->type), rr->ttl);
switch (rr->type)
{
case T_NS:
printf ("%s\n", (char *) rr->data);
break;
case T_A:
printf ("%d.%d.%d.%d\n",
((unsigned char *) rr->data)[0],
((unsigned char *) rr->data)[1],
((unsigned char *) rr->data)[2],
((unsigned char *) rr->data)[3]);
break;
case T_MX:
case T_AFSDB:
{
struct mx_record *mx = (struct mx_record *) rr->data;
printf ("%d %s\n", mx->preference, mx->domain);
break;
}
case T_SRV:
{
struct srv_record *srv = (struct srv_record *) rr->data;
printf ("%d %d %d %s\n", srv->priority, srv->weight,
srv->port, srv->target);
break;
}
default:
printf ("\n");
break;
}
}
return 0;
}
#endif