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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
*/
#include "ares_setup.h"
#ifdef HAVE_NETINET_IN_H
# include <netinet/in.h>
#endif
#include "ares_nameser.h"
#include "ares.h"
#include "ares_dns.h"
#include "ares_private.h"
struct qquery {
ares_callback callback;
void *arg;
};
static void qcallback(void *arg, int status, int timeouts, unsigned char *abuf, int alen);
/* a unique query id is generated using an rc4 key. Since the id may already
be used by a running query (as infrequent as it may be), a lookup is
performed per id generation. In practice this search should happen only
once per newly generated id
*/
static unsigned short generate_unique_id(ares_channel channel)
{
unsigned short id;
do {
id = ares__generate_new_id(channel->rand_state);
} while (ares__htable_stvp_get(channel->queries_by_qid, id, NULL));
return (unsigned short)id;
}
int ares_query_qid(ares_channel channel, const char *name,
int dnsclass, int type, ares_callback callback,
void *arg, unsigned short *qid)
{
struct qquery *qquery;
unsigned char *qbuf;
int qlen, rd, status;
unsigned short id = generate_unique_id(channel);
/* Compose the query. */
rd = !(channel->flags & ARES_FLAG_NORECURSE);
status = ares_create_query(name, dnsclass, type, id, rd, &qbuf,
&qlen, (channel->flags & ARES_FLAG_EDNS) ? channel->ednspsz : 0);
if (status != ARES_SUCCESS)
{
if (qbuf != NULL) ares_free(qbuf);
callback(arg, status, 0, NULL, 0);
return status;
}
/* Allocate and fill in the query structure. */
qquery = ares_malloc(sizeof(struct qquery));
if (!qquery)
{
ares_free_string(qbuf);
callback(arg, ARES_ENOMEM, 0, NULL, 0);
return ARES_ENOMEM;
}
qquery->callback = callback;
qquery->arg = arg;
/* Send it off. qcallback will be called when we get an answer. */
status = ares_send_ex(channel, qbuf, qlen, qcallback, qquery);
ares_free_string(qbuf);
if (status == ARES_SUCCESS && qid)
*qid = id;
return status;
}
void ares_query(ares_channel channel, const char *name, int dnsclass,
int type, ares_callback callback, void *arg)
{
ares_query_qid(channel, name, dnsclass, type, callback, arg, NULL);
}
static void qcallback(void *arg, int status, int timeouts, unsigned char *abuf, int alen)
{
struct qquery *qquery = (struct qquery *) arg;
unsigned int ancount;
int rcode;
if (status != ARES_SUCCESS)
qquery->callback(qquery->arg, status, timeouts, abuf, alen);
else
{
/* Pull the response code and answer count from the packet. */
rcode = DNS_HEADER_RCODE(abuf);
ancount = DNS_HEADER_ANCOUNT(abuf);
/* Convert errors. */
switch (rcode)
{
case NOERROR:
status = (ancount > 0) ? ARES_SUCCESS : ARES_ENODATA;
break;
case FORMERR:
status = ARES_EFORMERR;
break;
case SERVFAIL:
status = ARES_ESERVFAIL;
break;
case NXDOMAIN:
status = ARES_ENOTFOUND;
break;
case NOTIMP:
status = ARES_ENOTIMP;
break;
case REFUSED:
status = ARES_EREFUSED;
break;
}
qquery->callback(qquery->arg, status, timeouts, abuf, alen);
}
ares_free(qquery);
}
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