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/* MIT License
*
* Copyright (c) The c-ares project and its contributors
*
* 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
*/
/* =============================================================================
* NOTE: The below copyright is preserved from the original author. In
* October 2023, there were attempts made to contact the author in order
* gain approval for relicensing to the modern MIT license from the
* below 1989 variant, but all contact information for the author is
* no longer valid.
*
* Copyright (c) 2020 <danny.sonnenschein@platynum.ch>
*
* Permission to use, copy, modify, and distribute this
* software and its documentation for any purpose and without
* fee is hereby granted, provided that the above copyright
* notice appear in all copies and that both that copyright
* notice and this permission notice appear in supporting
* documentation, and that the name of M.I.T. not be used in
* advertising or publicity pertaining to distribution of the
* software without specific, written prior permission.
* M.I.T. makes no representations about the suitability of
* this software for any purpose. It is provided "as is"
* without express or implied warranty.
*
* =============================================================================
*/
#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"
int
ares_parse_caa_reply (const unsigned char *abuf, int alen,
struct ares_caa_reply **caa_out)
{
unsigned int qdcount, ancount, i;
const unsigned char *aptr;
const unsigned char *strptr;
int status, rr_type, rr_class, rr_len;
long len;
char *hostname = NULL, *rr_name = NULL;
struct ares_caa_reply *caa_head = NULL;
struct ares_caa_reply *caa_last = NULL;
struct ares_caa_reply *caa_curr;
/* Set *caa_out to NULL for all failure cases. */
*caa_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);
aptr += RRFIXEDSZ;
if (aptr + rr_len > abuf + alen)
{
status = ARES_EBADRESP;
break;
}
/* Check if we are really looking at a CAA record */
if ((rr_class == C_IN || rr_class == C_CHAOS) && rr_type == T_CAA)
{
strptr = aptr;
/* Allocate storage for this CAA answer appending it to the list */
caa_curr = ares_malloc_data(ARES_DATATYPE_CAA_REPLY);
if (!caa_curr)
{
status = ARES_ENOMEM;
break;
}
if (caa_last)
{
caa_last->next = caa_curr;
}
else
{
caa_head = caa_curr;
}
caa_last = caa_curr;
if (rr_len < 2)
{
status = ARES_EBADRESP;
break;
}
caa_curr->critical = (int)*strptr++;
caa_curr->plength = (int)*strptr++;
if (caa_curr->plength <= 0 || (int)caa_curr->plength >= rr_len - 2)
{
status = ARES_EBADRESP;
break;
}
caa_curr->property = ares_malloc (caa_curr->plength + 1/* Including null byte */);
if (caa_curr->property == NULL)
{
status = ARES_ENOMEM;
break;
}
memcpy ((char *) caa_curr->property, strptr, caa_curr->plength);
/* Make sure we NULL-terminate */
caa_curr->property[caa_curr->plength] = 0;
strptr += caa_curr->plength;
caa_curr->length = rr_len - caa_curr->plength - 2;
if (caa_curr->length <= 0)
{
status = ARES_EBADRESP;
break;
}
caa_curr->value = ares_malloc (caa_curr->length + 1/* Including null byte */);
if (caa_curr->value == NULL)
{
status = ARES_ENOMEM;
break;
}
memcpy ((char *) caa_curr->value, strptr, caa_curr->length);
/* Make sure we NULL-terminate */
caa_curr->value[caa_curr->length] = 0;
}
/* 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 (caa_head)
ares_free_data (caa_head);
return status;
}
/* everything looks fine, return the data */
*caa_out = caa_head;
return ARES_SUCCESS;
}
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