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/* Copyright 1998 by the Massachusetts Institute of Technology.
*
* 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
#include "ares_nameser.h"
#ifdef HAVE_STRINGS_H
# include <strings.h>
#endif
#ifdef HAVE_LIMITS_H
# include <limits.h>
#endif
#include "ares.h"
#include "ares_dns.h"
#include "ares_nowarn.h"
#include "ares_private.h"
int ares_parse_ptr_reply(const unsigned char *abuf, int alen, const void *addr,
int addrlen, int family, struct hostent **host,
int *hostttl)
{
unsigned int qdcount, ancount;
int status, i, rr_type, rr_class, rr_len, rr_ttl;
long len;
const unsigned char *aptr;
char *ptrname, *hostname, *rr_name, *rr_data;
struct hostent *hostent = NULL;
int aliascnt = 0;
int alias_alloc = 8;
char ** aliases;
size_t rr_data_len;
/* Set *host to NULL for all failure cases. */
*host = NULL;
if (hostttl)
*hostttl = INT_MAX;
/* 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, &ptrname, &len, 0);
if (status != ARES_SUCCESS)
return status;
if (aptr + len + QFIXEDSZ > abuf + alen)
{
ares_free(ptrname);
return ARES_EBADRESP;
}
aptr += len + QFIXEDSZ;
/* Examine each answer resource record (RR) in turn. */
hostname = NULL;
aliases = ares_malloc(alias_alloc * sizeof(char *));
if (!aliases)
{
ares_free(ptrname);
return ARES_ENOMEM;
}
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)
{
ares_free(rr_name);
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)
{
ares_free(rr_name);
status = ARES_EBADRESP;
break;
}
if (rr_class == C_IN && rr_type == T_PTR
&& strcasecmp(rr_name, ptrname) == 0)
{
/* Decode the RR data and set hostname to it. */
status = ares__expand_name_for_response(aptr, abuf, alen, &rr_data,
&len, 1);
if (status != ARES_SUCCESS)
{
ares_free(rr_name);
break;
}
if (hostname)
ares_free(hostname);
hostname = rr_data;
rr_data_len = strlen(rr_data)+1;
aliases[aliascnt] = ares_malloc(rr_data_len * sizeof(char));
if (!aliases[aliascnt])
{
ares_free(rr_name);
status = ARES_ENOMEM;
break;
}
strncpy(aliases[aliascnt], rr_data, rr_data_len);
aliascnt++;
if (aliascnt >= alias_alloc) {
char **ptr;
alias_alloc *= 2;
ptr = ares_realloc(aliases, alias_alloc * sizeof(char *));
if(!ptr) {
ares_free(rr_name);
status = ARES_ENOMEM;
break;
}
aliases = ptr;
}
if (hostttl)
{
if (*hostttl > rr_ttl)
{
*hostttl = rr_ttl;
}
}
}
if (rr_class == C_IN && rr_type == T_CNAME)
{
/* Decode the RR data and replace ptrname with it. */
status = ares__expand_name_for_response(aptr, abuf, alen, &rr_data,
&len, 1);
if (status != ARES_SUCCESS)
{
ares_free(rr_name);
break;
}
ares_free(ptrname);
ptrname = rr_data;
}
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 && !hostname)
status = ARES_ENODATA;
if (status == ARES_SUCCESS)
{
/* If we don't reach the end, we must have failed due to out of memory */
status = ARES_ENOMEM;
/* We got our answer. Allocate memory to build the host entry. */
hostent = ares_malloc(sizeof(*hostent));
if (!hostent)
goto fail;
/* If we don't memset here, cleanups may fail */
memset(hostent, 0, sizeof(*hostent));
hostent->h_addr_list = ares_malloc(2 * sizeof(char *));
if (!hostent->h_addr_list)
goto fail;
if (addr && addrlen) {
hostent->h_addr_list[0] = ares_malloc(addrlen);
if (!hostent->h_addr_list[0])
goto fail;
} else {
hostent->h_addr_list[0] = NULL;
}
hostent->h_aliases = ares_malloc((aliascnt+1) * sizeof (char *));
if (!hostent->h_aliases)
goto fail;
/* Fill in the hostent and return successfully. */
hostent->h_name = hostname;
for (i=0 ; i<aliascnt ; i++)
hostent->h_aliases[i] = aliases[i];
hostent->h_aliases[aliascnt] = NULL;
hostent->h_addrtype = aresx_sitoss(family);
hostent->h_length = aresx_sitoss(addrlen);
if (addr && addrlen)
memcpy(hostent->h_addr_list[0], addr, addrlen);
hostent->h_addr_list[1] = NULL;
*host = hostent;
ares_free(aliases);
ares_free(ptrname);
return ARES_SUCCESS;
}
fail:
ares_free_hostent(hostent);
for (i=0 ; i<aliascnt ; i++)
if (aliases[i])
ares_free(aliases[i]);
ares_free(aliases);
if (hostname)
ares_free(hostname);
ares_free(ptrname);
return status;
}
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