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/* Copyright (C) 2019 by Andrew Selivanov
*
* 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
#ifdef HAVE_LIMITS_H
# include <limits.h>
#endif
#include "ares.h"
#include "ares_dns.h"
#include "ares_private.h"
int ares__parse_into_addrinfo(const unsigned char *abuf,
int alen, int cname_only_is_enodata,
unsigned short port,
struct ares_addrinfo *ai)
{
unsigned int qdcount, ancount;
int status, i, rr_type, rr_class, rr_len, rr_ttl;
int got_a = 0, got_aaaa = 0, got_cname = 0;
long len;
const unsigned char *aptr;
char *question_hostname = NULL;
char *hostname, *rr_name = NULL, *rr_data;
struct ares_addrinfo_cname *cname, *cnames = NULL;
struct ares_addrinfo_node *nodes = 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, &question_hostname, &len, 0);
if (status != ARES_SUCCESS)
return status;
if (aptr + len + QFIXEDSZ > abuf + alen)
{
status = ARES_EBADRESP;
goto failed_stat;
}
hostname = question_hostname;
aptr += len + QFIXEDSZ;
/* 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)
{
rr_name = NULL;
goto failed_stat;
}
aptr += len;
if (aptr + RRFIXEDSZ > abuf + alen)
{
status = ARES_EBADRESP;
goto failed_stat;
}
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)
{
status = ARES_EBADRESP;
goto failed_stat;
}
if (rr_class == C_IN && rr_type == T_A
&& rr_len == sizeof(struct in_addr)
&& strcasecmp(rr_name, hostname) == 0)
{
got_a = 1;
if (aptr + sizeof(struct in_addr) > abuf + alen)
{ /* LCOV_EXCL_START: already checked above */
status = ARES_EBADRESP;
goto failed_stat;
} /* LCOV_EXCL_STOP */
status = ares_append_ai_node(AF_INET, port, rr_ttl, aptr, &nodes);
if (status != ARES_SUCCESS)
goto failed_stat;
}
else if (rr_class == C_IN && rr_type == T_AAAA
&& rr_len == sizeof(struct ares_in6_addr)
&& strcasecmp(rr_name, hostname) == 0)
{
got_aaaa = 1;
if (aptr + sizeof(struct ares_in6_addr) > abuf + alen)
{ /* LCOV_EXCL_START: already checked above */
status = ARES_EBADRESP;
goto failed_stat;
} /* LCOV_EXCL_STOP */
status = ares_append_ai_node(AF_INET6, port, rr_ttl, aptr, &nodes);
if (status != ARES_SUCCESS)
goto failed_stat;
}
if (rr_class == C_IN && rr_type == T_CNAME)
{
got_cname = 1;
status = ares__expand_name_for_response(aptr, abuf, alen, &rr_data,
&len, 1);
if (status != ARES_SUCCESS)
{
goto failed_stat;
}
/* Decode the RR data and replace the hostname with it. */
/* SA: Seems wrong as it introduses order dependency. */
hostname = rr_data;
cname = ares__append_addrinfo_cname(&cnames);
if (!cname)
{
status = ARES_ENOMEM;
ares_free(rr_data);
goto failed_stat;
}
cname->ttl = rr_ttl;
cname->alias = rr_name;
cname->name = rr_data;
rr_name = NULL;
}
else
{
/* rr_name is only saved for cname */
ares_free(rr_name);
rr_name = NULL;
}
aptr += rr_len;
if (aptr > abuf + alen)
{ /* LCOV_EXCL_START: already checked above */
status = ARES_EBADRESP;
goto failed_stat;
} /* LCOV_EXCL_STOP */
}
if (status == ARES_SUCCESS)
{
if (!got_a && !got_aaaa)
{
if (!got_cname || (got_cname && cname_only_is_enodata))
{
status = ARES_ENODATA;
goto failed_stat;
}
}
/* save the question hostname as ai->name */
if (ai->name == NULL || strcasecmp(ai->name, question_hostname) != 0)
{
ares_free(ai->name);
ai->name = ares_strdup(question_hostname);
if (!ai->name)
{
status = ARES_ENOMEM;
goto failed_stat;
}
}
if (got_a || got_aaaa)
{
ares__addrinfo_cat_nodes(&ai->nodes, nodes);
nodes = NULL;
}
if (got_cname)
{
ares__addrinfo_cat_cnames(&ai->cnames, cnames);
cnames = NULL;
}
}
ares_free(question_hostname);
return status;
failed_stat:
ares_free(question_hostname);
ares_free(rr_name);
ares__freeaddrinfo_cnames(cnames);
ares__freeaddrinfo_nodes(nodes);
return status;
}
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