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/* MIT License
*
* Copyright (c) 1998 Massachusetts Institute of Technology
* Copyright (c) 2009 Jakub Hrozek
*
* 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 (including the next
* paragraph) 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.
*
* SPDX-License-Identifier: MIT
*/
#include "ares_setup.h"
#ifdef HAVE_NETINET_IN_H
# include <netinet/in.h>
#endif
#ifdef HAVE_NETDB_H
# include <netdb.h>
#endif
#ifdef HAVE_ARPA_INET_H
# include <arpa/inet.h>
#endif
#include "ares_nameser.h"
#ifdef HAVE_STRINGS_H
# include <strings.h>
#endif
#include "ares.h"
#include "ares_dns.h"
#include "ares_data.h"
#include "ares_private.h"
static int
ares__parse_txt_reply (const unsigned char *abuf, int alen,
int ex, void **txt_out)
{
size_t substr_len;
unsigned int qdcount, ancount, i;
const unsigned char *aptr;
const unsigned char *strptr;
int status, rr_type, rr_class, rr_len, rr_ttl;
long len;
char *hostname = NULL, *rr_name = NULL;
struct ares_txt_ext *txt_head = NULL;
struct ares_txt_ext *txt_last = NULL;
struct ares_txt_ext *txt_curr;
/* Set *txt_out to NULL for all failure cases. */
*txt_out = NULL;
/* Give up if abuf doesn't have room for a header. */
if (alen < HFIXEDSZ)
return ARES_EBADRESP;
/* Fetch the question and answer count from the header. */
qdcount = DNS_HEADER_QDCOUNT (abuf);
ancount = DNS_HEADER_ANCOUNT (abuf);
if (qdcount != 1)
return ARES_EBADRESP;
if (ancount == 0)
return ARES_ENODATA;
/* Expand the name from the question, and skip past the question. */
aptr = abuf + HFIXEDSZ;
status = ares_expand_name (aptr, abuf, alen, &hostname, &len);
if (status != ARES_SUCCESS)
return status;
if (aptr + len + QFIXEDSZ > abuf + alen)
{
ares_free (hostname);
return ARES_EBADRESP;
}
aptr += len + QFIXEDSZ;
/* Examine each answer resource record (RR) in turn. */
for (i = 0; i < ancount; i++)
{
/* Decode the RR up to the data field. */
status = ares_expand_name (aptr, abuf, alen, &rr_name, &len);
if (status != ARES_SUCCESS)
{
break;
}
aptr += len;
if (aptr + RRFIXEDSZ > abuf + alen)
{
status = ARES_EBADRESP;
break;
}
rr_type = DNS_RR_TYPE (aptr);
rr_class = DNS_RR_CLASS (aptr);
rr_len = DNS_RR_LEN (aptr);
rr_ttl = DNS_RR_TTL (aptr);
aptr += RRFIXEDSZ;
if (aptr + rr_len > abuf + alen)
{
status = ARES_EBADRESP;
break;
}
/* Check if we are really looking at a TXT record */
if ((rr_class == C_IN || rr_class == C_CHAOS) && rr_type == T_TXT)
{
/*
* There may be multiple substrings in a single TXT record. Each
* substring may be up to 255 characters in length, with a
* "length byte" indicating the size of the substring payload.
* RDATA contains both the length-bytes and payloads of all
* substrings contained therein.
*/
strptr = aptr;
while (strptr < (aptr + rr_len))
{
substr_len = (unsigned char)*strptr;
if (strptr + substr_len + 1 > aptr + rr_len)
{
status = ARES_EBADRESP;
break;
}
/* Allocate storage for this TXT answer appending it to the list */
txt_curr = ares_malloc_data(ex ? ARES_DATATYPE_TXT_EXT :
ARES_DATATYPE_TXT_REPLY);
if (!txt_curr)
{
status = ARES_ENOMEM;
break;
}
if (txt_last)
{
txt_last->next = txt_curr;
}
else
{
txt_head = txt_curr;
}
txt_last = txt_curr;
if (ex)
txt_curr->record_start = (strptr == aptr);
txt_curr->length = substr_len;
txt_curr->txt = ares_malloc (substr_len + 1/* Including null byte */);
if (txt_curr->txt == NULL)
{
status = ARES_ENOMEM;
break;
}
++strptr;
memcpy ((char *) txt_curr->txt, strptr, substr_len);
/* Make sure we NULL-terminate */
txt_curr->txt[substr_len] = 0;
txt_curr->ttl = rr_ttl;
strptr += substr_len;
}
}
/* Propagate any failures */
if (status != ARES_SUCCESS)
{
break;
}
/* Don't lose memory in the next iteration */
ares_free (rr_name);
rr_name = NULL;
/* Move on to the next record */
aptr += rr_len;
}
if (hostname)
ares_free (hostname);
if (rr_name)
ares_free (rr_name);
/* clean up on error */
if (status != ARES_SUCCESS)
{
if (txt_head)
ares_free_data (txt_head);
return status;
}
/* everything looks fine, return the data */
*txt_out = txt_head;
return ARES_SUCCESS;
}
int
ares_parse_txt_reply (const unsigned char *abuf, int alen,
struct ares_txt_reply **txt_out)
{
return ares__parse_txt_reply(abuf, alen, 0, (void **) txt_out);
}
int
ares_parse_txt_reply_ext (const unsigned char *abuf, int alen,
struct ares_txt_ext **txt_out)
{
return ares__parse_txt_reply(abuf, alen, 1, (void **) txt_out);
}
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