ares_parse_uri_reply.c
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/* Copyright 1998 by the Massachusetts Institute of Technology.
* Copyright (C) 2009 by Jakub Hrozek <jhrozek@redhat.com>
*
* 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"
#include "ares.h"
#include "ares_dns.h"
#include "ares_data.h"
#include "ares_private.h"
/* AIX portability check */
#ifndef T_URI
# define T_URI 256 /* uri selection */
#endif
int
ares_parse_uri_reply (const unsigned char *abuf, int alen,
struct ares_uri_reply **uri_out)
{
unsigned int qdcount, ancount, i;
const unsigned char *aptr, *vptr;
int status, rr_type, rr_class, rr_len, rr_ttl;
long len;
char *uri_str = NULL, *rr_name = NULL;
struct ares_uri_reply *uri_head = NULL;
struct ares_uri_reply *uri_last = NULL;
struct ares_uri_reply *uri_curr;
/* Set *uri_out to NULL for all failure cases. */
*uri_out = 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;
}
if (ancount == 0) {
return ARES_ENODATA;
}
/* Expand the name from the question, and skip past the question. */
aptr = abuf + HFIXEDSZ;
status = ares_expand_name (aptr, abuf, alen, &uri_str, &len);
if (status != ARES_SUCCESS){
return status;
}
if (aptr + len + QFIXEDSZ > abuf + alen)
{
ares_free (uri_str);
return ARES_EBADRESP;
}
aptr += len + QFIXEDSZ;
/* Examine each answer resource record (RR) in turn. */
for (i = 0; i < ancount; i++)
{
/* Decode the RR up to the data field. */
status = ares_expand_name (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_ttl = DNS_RR_TTL(aptr);
rr_len = DNS_RR_LEN (aptr);
aptr += RRFIXEDSZ;
if (aptr + rr_len > abuf + alen)
{
status = ARES_EBADRESP;
break;
}
/* Check if we are really looking at a URI record */
if (rr_class == C_IN && rr_type == T_URI)
{
/* parse the URI record itself */
if (rr_len < 5)
{
status = ARES_EBADRESP;
break;
}
/* Allocate storage for this URI answer appending it to the list */
uri_curr = ares_malloc_data(ARES_DATATYPE_URI_REPLY);
if (!uri_curr)
{
status = ARES_ENOMEM;
break;
}
if (uri_last)
{
uri_last->next = uri_curr;
}
else
{
uri_head = uri_curr;
}
uri_last = uri_curr;
vptr = aptr;
uri_curr->priority = DNS__16BIT(vptr);
vptr += sizeof(unsigned short);
uri_curr->weight = DNS__16BIT(vptr);
vptr += sizeof(unsigned short);
uri_curr->uri = (char *)ares_malloc(rr_len-3);
if (!uri_curr->uri)
{
status = ARES_ENOMEM;
break;
}
uri_curr->uri = strncpy(uri_curr->uri, (const char *)vptr, rr_len-4);
uri_curr->uri[rr_len-4]='\0';
uri_curr->ttl = rr_ttl;
if (status != ARES_SUCCESS)
break;
}
/* Don't lose memory in the next iteration */
ares_free (rr_name);
rr_name = NULL;
/* Move on to the next record */
aptr += rr_len;
}
if (uri_str)
ares_free (uri_str);
if (rr_name)
ares_free (rr_name);
/* clean up on error */
if (status != ARES_SUCCESS)
{
if (uri_head)
ares_free_data (uri_head);
return status;
}
/* everything looks fine, return the data */
*uri_out = uri_head;
return ARES_SUCCESS;
}