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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
#include "ares_nameser.h"
#include "ares.h"
#include "ares_dns.h"
#include "ares_private.h"
void ares_send(ares_channel channel, const unsigned char *qbuf, int qlen,
ares_callback callback, void *arg)
{
struct query *query;
int i, packetsz;
struct timeval now;
/* Verify that the query is at least long enough to hold the header. */
if (qlen < HFIXEDSZ || qlen >= (1 << 16))
{
callback(arg, ARES_EBADQUERY, 0, NULL, 0);
return;
}
if (channel->nservers < 1)
{
callback(arg, ARES_ESERVFAIL, 0, NULL, 0);
return;
}
/* Allocate space for query and allocated fields. */
query = ares_malloc(sizeof(struct query));
if (!query)
{
callback(arg, ARES_ENOMEM, 0, NULL, 0);
return;
}
query->tcpbuf = ares_malloc(qlen + 2);
if (!query->tcpbuf)
{
ares_free(query);
callback(arg, ARES_ENOMEM, 0, NULL, 0);
return;
}
query->server_info = ares_malloc(channel->nservers *
sizeof(query->server_info[0]));
if (!query->server_info)
{
ares_free(query->tcpbuf);
ares_free(query);
callback(arg, ARES_ENOMEM, 0, NULL, 0);
return;
}
/* Compute the query ID. Start with no timeout. */
query->qid = DNS_HEADER_QID(qbuf);
query->timeout.tv_sec = 0;
query->timeout.tv_usec = 0;
/* Form the TCP query buffer by prepending qlen (as two
* network-order bytes) to qbuf.
*/
query->tcpbuf[0] = (unsigned char)((qlen >> 8) & 0xff);
query->tcpbuf[1] = (unsigned char)(qlen & 0xff);
memcpy(query->tcpbuf + 2, qbuf, qlen);
query->tcplen = qlen + 2;
/* Fill in query arguments. */
query->qbuf = query->tcpbuf + 2;
query->qlen = qlen;
query->callback = callback;
query->arg = arg;
/* Initialize query status. */
query->try_count = 0;
/* Choose the server to send the query to. If rotation is enabled, keep track
* of the next server we want to use. */
query->server = channel->last_server;
if (channel->rotate == 1)
channel->last_server = (channel->last_server + 1) % channel->nservers;
for (i = 0; i < channel->nservers; i++)
{
query->server_info[i].skip_server = 0;
query->server_info[i].tcp_connection_generation = 0;
}
packetsz = (channel->flags & ARES_FLAG_EDNS) ? channel->ednspsz : PACKETSZ;
query->using_tcp = (channel->flags & ARES_FLAG_USEVC) || qlen > packetsz;
query->error_status = ARES_ECONNREFUSED;
query->timeouts = 0;
/* Initialize our list nodes. */
ares__init_list_node(&(query->queries_by_qid), query);
ares__init_list_node(&(query->queries_by_timeout), query);
ares__init_list_node(&(query->queries_to_server), query);
ares__init_list_node(&(query->all_queries), query);
/* Chain the query into the list of all queries. */
ares__insert_in_list(&(query->all_queries), &(channel->all_queries));
/* Keep track of queries bucketed by qid, so we can process DNS
* responses quickly.
*/
ares__insert_in_list(
&(query->queries_by_qid),
&(channel->queries_by_qid[query->qid % ARES_QID_TABLE_SIZE]));
/* Perform the first query action. */
now = ares__tvnow();
ares__send_query(channel, query, &now);
}
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