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/* MIT License
*
* Copyright (c) 1998 Massachusetts Institute of Technology
* 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
*/
/*
* ares_parse_ns_reply created by Vlad Dinulescu <vlad.dinulescu@avira.com>
* on behalf of AVIRA Gmbh - http://www.avira.com
*/
#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"
#include "ares.h"
#include "ares_dns.h"
#include "ares_private.h"
int ares_parse_ns_reply( const unsigned char* abuf, int alen,
struct hostent** host )
{
unsigned int qdcount, ancount;
int status, i, rr_type, rr_class, rr_len;
int nameservers_num;
long len;
const unsigned char *aptr;
char* hostname, *rr_name, *rr_data, **nameservers;
struct hostent *hostent;
/* Set *host to NULL for all failure cases. */
*host = 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;
/* Expand the name from the question, and skip past the question. */
aptr = abuf + HFIXEDSZ;
status = ares__expand_name_for_response( aptr, abuf, alen, &hostname, &len, 0);
if ( status != ARES_SUCCESS )
return status;
if ( aptr + len + QFIXEDSZ > abuf + alen )
{
ares_free( hostname );
return ARES_EBADRESP;
}
aptr += len + QFIXEDSZ;
/* Allocate nameservers array; ancount gives an upper bound */
nameservers = ares_malloc( ( ancount + 1 ) * sizeof( char * ) );
if ( !nameservers )
{
ares_free( hostname );
return ARES_ENOMEM;
}
nameservers_num = 0;
/* Examine each answer resource record (RR) in turn. */
for ( i = 0; i < ( int ) ancount; i++ )
{
/* Decode the RR up to the data field. */
status = ares__expand_name_for_response( aptr, abuf, alen, &rr_name, &len, 0);
if ( status != ARES_SUCCESS )
break;
aptr += len;
if ( aptr + RRFIXEDSZ > abuf + alen )
{
status = ARES_EBADRESP;
ares_free(rr_name);
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)
{
ares_free(rr_name);
status = ARES_EBADRESP;
break;
}
if ( rr_class == C_IN && rr_type == T_NS )
{
/* Decode the RR data and add it to the nameservers list */
status = ares__expand_name_for_response( aptr, abuf, alen, &rr_data,
&len, 1);
if ( status != ARES_SUCCESS )
{
ares_free(rr_name);
break;
}
nameservers[nameservers_num] = ares_malloc(strlen(rr_data)+1);
if (nameservers[nameservers_num]==NULL)
{
ares_free(rr_name);
ares_free(rr_data);
status=ARES_ENOMEM;
break;
}
strcpy(nameservers[nameservers_num],rr_data);
ares_free(rr_data);
nameservers_num++;
}
ares_free( rr_name );
aptr += rr_len;
if ( aptr > abuf + alen )
{ /* LCOV_EXCL_START: already checked above */
status = ARES_EBADRESP;
break;
} /* LCOV_EXCL_STOP */
}
if ( status == ARES_SUCCESS && nameservers_num == 0 )
{
status = ARES_ENODATA;
}
if ( status == ARES_SUCCESS )
{
/* We got our answer. Allocate memory to build the host entry. */
nameservers[nameservers_num] = NULL;
hostent = ares_malloc( sizeof( struct hostent ) );
if ( hostent )
{
hostent->h_addr_list = ares_malloc( 1 * sizeof( char * ) );
if ( hostent->h_addr_list )
{
/* Fill in the hostent and return successfully. */
hostent->h_name = hostname;
hostent->h_aliases = nameservers;
hostent->h_addrtype = AF_INET;
hostent->h_length = sizeof( struct in_addr );
hostent->h_addr_list[0] = NULL;
*host = hostent;
return ARES_SUCCESS;
}
ares_free( hostent );
}
status = ARES_ENOMEM;
}
for ( i = 0; i < nameservers_num; i++ )
ares_free( nameservers[i] );
ares_free( nameservers );
ares_free( hostname );
return status;
}
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