132 lines
3.9 KiB
C
132 lines
3.9 KiB
C
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/* Copyright 1998 by the Massachusetts Institute of Technology.
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*
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* Permission to use, copy, modify, and distribute this
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* software and its documentation for any purpose and without
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* fee is hereby granted, provided that the above copyright
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* notice appear in all copies and that both that copyright
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* notice and this permission notice appear in supporting
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* documentation, and that the name of M.I.T. not be used in
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* advertising or publicity pertaining to distribution of the
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* software without specific, written prior permission.
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* M.I.T. makes no representations about the suitability of
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* this software for any purpose. It is provided "as is"
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* without express or implied warranty.
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*/
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#include "ares_setup.h"
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#ifdef HAVE_NETINET_IN_H
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# include <netinet/in.h>
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#endif
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#ifdef HAVE_ARPA_NAMESER_H
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# include <arpa/nameser.h>
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#else
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# include "nameser.h"
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#endif
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#ifdef HAVE_ARPA_NAMESER_COMPAT_H
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# include <arpa/nameser_compat.h>
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#endif
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#include "ares.h"
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#include "ares_dns.h"
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#include "ares_private.h"
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void ares_send(ares_channel channel, const unsigned char *qbuf, int qlen,
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ares_callback callback, void *arg)
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{
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struct query *query;
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int i, packetsz;
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struct timeval now;
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/* Verify that the query is at least long enough to hold the header. */
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if (qlen < HFIXEDSZ || qlen >= (1 << 16))
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{
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callback(arg, ARES_EBADQUERY, 0, NULL, 0);
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return;
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}
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/* Allocate space for query and allocated fields. */
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query = ares_malloc(sizeof(struct query));
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if (!query)
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{
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callback(arg, ARES_ENOMEM, 0, NULL, 0);
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return;
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}
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query->tcpbuf = ares_malloc(qlen + 2);
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if (!query->tcpbuf)
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{
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ares_free(query);
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callback(arg, ARES_ENOMEM, 0, NULL, 0);
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return;
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}
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query->server_info = ares_malloc(channel->nservers *
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sizeof(query->server_info[0]));
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if (!query->server_info)
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{
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ares_free(query->tcpbuf);
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ares_free(query);
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callback(arg, ARES_ENOMEM, 0, NULL, 0);
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return;
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}
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/* Compute the query ID. Start with no timeout. */
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query->qid = DNS_HEADER_QID(qbuf);
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query->timeout.tv_sec = 0;
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query->timeout.tv_usec = 0;
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/* Form the TCP query buffer by prepending qlen (as two
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* network-order bytes) to qbuf.
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*/
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query->tcpbuf[0] = (unsigned char)((qlen >> 8) & 0xff);
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query->tcpbuf[1] = (unsigned char)(qlen & 0xff);
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memcpy(query->tcpbuf + 2, qbuf, qlen);
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query->tcplen = qlen + 2;
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/* Fill in query arguments. */
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query->qbuf = query->tcpbuf + 2;
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query->qlen = qlen;
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query->callback = callback;
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query->arg = arg;
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/* Initialize query status. */
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query->try_count = 0;
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/* Choose the server to send the query to. If rotation is enabled, keep track
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* of the next server we want to use. */
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query->server = channel->last_server;
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if (channel->rotate == 1)
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channel->last_server = (channel->last_server + 1) % channel->nservers;
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for (i = 0; i < channel->nservers; i++)
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{
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query->server_info[i].skip_server = 0;
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query->server_info[i].tcp_connection_generation = 0;
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}
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packetsz = (channel->flags & ARES_FLAG_EDNS) ? channel->ednspsz : PACKETSZ;
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query->using_tcp = (channel->flags & ARES_FLAG_USEVC) || qlen > packetsz;
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query->error_status = ARES_ECONNREFUSED;
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query->timeouts = 0;
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/* Initialize our list nodes. */
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ares__init_list_node(&(query->queries_by_qid), query);
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ares__init_list_node(&(query->queries_by_timeout), query);
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ares__init_list_node(&(query->queries_to_server), query);
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ares__init_list_node(&(query->all_queries), query);
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/* Chain the query into the list of all queries. */
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ares__insert_in_list(&(query->all_queries), &(channel->all_queries));
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/* Keep track of queries bucketed by qid, so we can process DNS
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* responses quickly.
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*/
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ares__insert_in_list(
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&(query->queries_by_qid),
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&(channel->queries_by_qid[query->qid % ARES_QID_TABLE_SIZE]));
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/* Perform the first query action. */
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now = ares__tvnow();
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ares__send_query(channel, query, &now);
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}
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