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/* MIT License
*
* Copyright (c) 2023 Brad House
*
* 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
#include "ares.h"
#include "ares_private.h"
int ares_parse_ptr_reply(const unsigned char *abuf, int alen_int,
const void *addr, int addrlen, int family,
struct hostent **host)
{
ares_status_t status;
size_t alen;
size_t ptrcount = 0;
struct hostent *hostent = NULL;
const char *hostname = NULL;
const char *ptrname = NULL;
ares_dns_record_t *dnsrec = NULL;
size_t i;
size_t ancount;
*host = NULL;
if (alen_int < 0) {
return ARES_EBADRESP;
}
alen = (size_t)alen_int;
status = ares_dns_parse(abuf, alen, 0, &dnsrec);
if (status != ARES_SUCCESS) {
goto done;
}
/* Fetch name from query as we will use it to compare later on. Old code
* did this check, so we'll retain it. */
status = ares_dns_record_query_get(dnsrec, 0, &ptrname, NULL, NULL);
if (status != ARES_SUCCESS) {
goto done;
}
ancount = ares_dns_record_rr_cnt(dnsrec, ARES_SECTION_ANSWER);
if (ancount == 0) {
status = ARES_ENODATA;
goto done;
}
/* Response structure */
hostent = ares_malloc(sizeof(*hostent));
if (hostent == NULL) {
status = ARES_ENOMEM;
goto done;
}
memset(hostent, 0, sizeof(*hostent));
hostent->h_addr_list = ares_malloc(2 * sizeof(*hostent->h_addr_list));
if (hostent->h_addr_list == NULL) {
status = ARES_ENOMEM;
goto done;
}
memset(hostent->h_addr_list, 0, 2 * sizeof(*hostent->h_addr_list));
if (addr != NULL && addrlen > 0) {
hostent->h_addr_list[0] = ares_malloc((size_t)addrlen);
if (hostent->h_addr_list[0] == NULL) {
status = ARES_ENOMEM;
goto done;
}
memcpy(hostent->h_addr_list[0], addr, (size_t)addrlen);
}
hostent->h_addrtype = (HOSTENT_ADDRTYPE_TYPE)family;
hostent->h_length = (HOSTENT_LENGTH_TYPE)addrlen;
/* Preallocate the maximum number + 1 */
hostent->h_aliases = ares_malloc((ancount + 1) * sizeof(*hostent->h_aliases));
if (hostent->h_aliases == NULL) {
status = ARES_ENOMEM;
goto done;
}
memset(hostent->h_aliases, 0, (ancount + 1) * sizeof(*hostent->h_aliases));
/* Cycle through answers */
for (i = 0; i < ancount; i++) {
const ares_dns_rr_t *rr =
ares_dns_record_rr_get(dnsrec, ARES_SECTION_ANSWER, i);
if (rr == NULL) {
/* Shouldn't be possible */
status = ARES_EBADRESP;
goto done;
}
if (ares_dns_rr_get_class(rr) != ARES_CLASS_IN) {
continue;
}
/* Any time we see a CNAME, replace our ptrname with its value */
if (ares_dns_rr_get_type(rr) == ARES_REC_TYPE_CNAME) {
ptrname = ares_dns_rr_get_str(rr, ARES_RR_CNAME_CNAME);
if (ptrname == NULL) {
status = ARES_EBADRESP;
goto done;
}
}
/* Handling for PTR records below this, otherwise skip */
if (ares_dns_rr_get_type(rr) != ARES_REC_TYPE_PTR) {
continue;
}
/* Issue #683
* Old code compared the name in the rr to the ptrname, but I think this
* is wrong since it was proven wrong for A & AAAA records. Leaving
* this code commented out for future reference
*
* rname = ares_dns_rr_get_name(rr);
* if (rname == NULL) {
* status = ARES_EBADRESP;
* goto done;
* }
* if (strcasecmp(ptrname, rname) != 0) {
* continue;
* }
*/
/* Save most recent PTR record as the hostname */
hostname = ares_dns_rr_get_str(rr, ARES_RR_PTR_DNAME);
if (hostname == NULL) {
status = ARES_EBADRESP;
goto done;
}
/* Append as an alias */
hostent->h_aliases[ptrcount] = ares_strdup(hostname);
if (hostent->h_aliases[ptrcount] == NULL) {
status = ARES_ENOMEM;
goto done;
}
ptrcount++;
}
if (ptrcount == 0) {
status = ARES_ENODATA;
goto done;
} else {
status = ARES_SUCCESS;
}
/* Fill in hostname */
hostent->h_name = ares_strdup(hostname);
if (hostent->h_name == NULL) {
status = ARES_ENOMEM;
goto done;
}
done:
if (status != ARES_SUCCESS) {
ares_free_hostent(hostent);
/* Compatibility */
if (status == ARES_EBADNAME) {
status = ARES_EBADRESP;
}
} else {
*host = hostent;
}
ares_dns_record_destroy(dnsrec);
return (int)status;
}
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