32b75d1b69
that is now used by the ares_parse_*_reply() functions instead of the ares_expand_name() simply to easier return ARES_EBADRESP for the cases where the name expansion fails as in responses that really isn't expected.
255 lines
7.0 KiB
C
255 lines
7.0 KiB
C
/* $Id$ */
|
|
|
|
/* 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 "setup.h"
|
|
|
|
#ifdef HAVE_SYS_SOCKET_H
|
|
# include <sys/socket.h>
|
|
#endif
|
|
#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
|
|
#ifdef HAVE_ARPA_NAMESER_H
|
|
# include <arpa/nameser.h>
|
|
#else
|
|
# include "nameser.h"
|
|
#endif
|
|
#ifdef HAVE_ARPA_NAMESER_COMPAT_H
|
|
# include <arpa/nameser_compat.h>
|
|
#endif
|
|
|
|
#ifdef HAVE_STRINGS_H
|
|
# include <strings.h>
|
|
#endif
|
|
|
|
#include <stdlib.h>
|
|
#include <string.h>
|
|
#include <limits.h>
|
|
#include "ares.h"
|
|
#include "ares_dns.h"
|
|
#include "ares_private.h"
|
|
|
|
int ares_parse_a_reply(const unsigned char *abuf, int alen,
|
|
struct hostent **host,
|
|
struct addrttl *addrttls, int *naddrttls)
|
|
{
|
|
unsigned int qdcount, ancount;
|
|
int status, i, rr_type, rr_class, rr_len, rr_ttl, naddrs;
|
|
int cname_ttl = INT_MAX; /* the TTL imposed by the CNAME chain */
|
|
int naliases;
|
|
long len;
|
|
const unsigned char *aptr;
|
|
char *hostname, *rr_name, *rr_data, **aliases;
|
|
struct in_addr *addrs;
|
|
struct hostent *hostent;
|
|
const int max_addr_ttls = (addrttls && naddrttls) ? *naddrttls : 0;
|
|
|
|
/* Set *host to NULL for all failure cases. */
|
|
if (host)
|
|
*host = NULL;
|
|
/* Same with *naddrttls. */
|
|
if (naddrttls)
|
|
*naddrttls = 0;
|
|
|
|
/* 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);
|
|
if (status != ARES_SUCCESS)
|
|
return status;
|
|
if (aptr + len + QFIXEDSZ > abuf + alen)
|
|
{
|
|
free(hostname);
|
|
return ARES_EBADRESP;
|
|
}
|
|
aptr += len + QFIXEDSZ;
|
|
|
|
if (host)
|
|
{
|
|
/* Allocate addresses and aliases; ancount gives an upper bound for
|
|
both. */
|
|
addrs = malloc(ancount * sizeof(struct in_addr));
|
|
if (!addrs)
|
|
{
|
|
free(hostname);
|
|
return ARES_ENOMEM;
|
|
}
|
|
aliases = malloc((ancount + 1) * sizeof(char *));
|
|
if (!aliases)
|
|
{
|
|
free(hostname);
|
|
free(addrs);
|
|
return ARES_ENOMEM;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
addrs = NULL;
|
|
aliases = NULL;
|
|
}
|
|
|
|
naddrs = 0;
|
|
naliases = 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);
|
|
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 (rr_class == C_IN && rr_type == T_A
|
|
&& rr_len == sizeof(struct in_addr)
|
|
&& strcasecmp(rr_name, hostname) == 0)
|
|
{
|
|
if (addrs)
|
|
{
|
|
if (aptr + sizeof(struct in_addr) > abuf + alen)
|
|
{
|
|
status = ARES_EBADRESP;
|
|
break;
|
|
}
|
|
memcpy(&addrs[naddrs], aptr, sizeof(struct in_addr));
|
|
}
|
|
if (naddrs < max_addr_ttls)
|
|
{
|
|
struct addrttl * const at = &addrttls[naddrs];
|
|
if (aptr + sizeof(struct in_addr) > abuf + alen)
|
|
{
|
|
status = ARES_EBADRESP;
|
|
break;
|
|
}
|
|
memcpy(&at->ipaddr, aptr, sizeof(struct in_addr));
|
|
at->ttl = rr_ttl;
|
|
}
|
|
naddrs++;
|
|
status = ARES_SUCCESS;
|
|
}
|
|
|
|
if (rr_class == C_IN && rr_type == T_CNAME)
|
|
{
|
|
/* Record the RR name as an alias. */
|
|
if (aliases)
|
|
aliases[naliases] = rr_name;
|
|
else
|
|
free(rr_name);
|
|
naliases++;
|
|
|
|
/* Decode the RR data and replace the hostname with it. */
|
|
status = ares__expand_name_for_response(aptr, abuf, alen, &rr_data,
|
|
&len);
|
|
if (status != ARES_SUCCESS)
|
|
break;
|
|
free(hostname);
|
|
hostname = rr_data;
|
|
|
|
/* Take the min of the TTLs we see in the CNAME chain. */
|
|
if (cname_ttl > rr_ttl)
|
|
cname_ttl = rr_ttl;
|
|
}
|
|
else
|
|
free(rr_name);
|
|
|
|
aptr += rr_len;
|
|
if (aptr > abuf + alen)
|
|
{
|
|
status = ARES_EBADRESP;
|
|
break;
|
|
}
|
|
}
|
|
|
|
if (status == ARES_SUCCESS && naddrs == 0)
|
|
status = ARES_ENODATA;
|
|
if (status == ARES_SUCCESS)
|
|
{
|
|
/* We got our answer. */
|
|
if (naddrttls)
|
|
{
|
|
const int n = naddrs < max_addr_ttls ? naddrs : max_addr_ttls;
|
|
for (i = 0; i < n; i++)
|
|
{
|
|
/* Ensure that each A TTL is no larger than the CNAME TTL. */
|
|
if (addrttls[i].ttl > cname_ttl)
|
|
addrttls[i].ttl = cname_ttl;
|
|
}
|
|
*naddrttls = n;
|
|
}
|
|
if (aliases)
|
|
aliases[naliases] = NULL;
|
|
if (host)
|
|
{
|
|
/* Allocate memory to build the host entry. */
|
|
hostent = malloc(sizeof(struct hostent));
|
|
if (hostent)
|
|
{
|
|
hostent->h_addr_list = malloc((naddrs + 1) * sizeof(char *));
|
|
if (hostent->h_addr_list)
|
|
{
|
|
/* Fill in the hostent and return successfully. */
|
|
hostent->h_name = hostname;
|
|
hostent->h_aliases = aliases;
|
|
hostent->h_addrtype = AF_INET;
|
|
hostent->h_length = sizeof(struct in_addr);
|
|
for (i = 0; i < naddrs; i++)
|
|
hostent->h_addr_list[i] = (char *) &addrs[i];
|
|
hostent->h_addr_list[naddrs] = NULL;
|
|
*host = hostent;
|
|
return ARES_SUCCESS;
|
|
}
|
|
free(hostent);
|
|
}
|
|
status = ARES_ENOMEM;
|
|
}
|
|
}
|
|
if (aliases)
|
|
{
|
|
for (i = 0; i < naliases; i++)
|
|
free(aliases[i]);
|
|
free(aliases);
|
|
}
|
|
free(addrs);
|
|
free(hostname);
|
|
return status;
|
|
}
|