2 /* Copyright 1998 by the Massachusetts Institute of Technology.
4 * Permission to use, copy, modify, and distribute this
5 * software and its documentation for any purpose and without
6 * fee is hereby granted, provided that the above copyright
7 * notice appear in all copies and that both that copyright
8 * notice and this permission notice appear in supporting
9 * documentation, and that the name of M.I.T. not be used in
10 * advertising or publicity pertaining to distribution of the
11 * software without specific, written prior permission.
12 * M.I.T. makes no representations about the suitability of
13 * this software for any purpose. It is provided "as is"
14 * without express or implied warranty.
17 #include "ares_setup.h"
19 #ifdef HAVE_NETINET_IN_H
20 # include <netinet/in.h>
22 #ifdef HAVE_ARPA_NAMESER_H
23 # include <arpa/nameser.h>
27 #ifdef HAVE_ARPA_NAMESER_COMPAT_H
28 # include <arpa/nameser_compat.h>
33 #include "ares_private.h"
35 void ares_send(ares_channel channel, const unsigned char *qbuf, int qlen,
36 ares_callback callback, void *arg)
42 /* Verify that the query is at least long enough to hold the header. */
43 if (qlen < HFIXEDSZ || qlen >= (1 << 16))
45 callback(arg, ARES_EBADQUERY, 0, NULL, 0);
49 /* Allocate space for query and allocated fields. */
50 query = malloc(sizeof(struct query));
53 callback(arg, ARES_ENOMEM, 0, NULL, 0);
56 query->tcpbuf = malloc(qlen + 2);
60 callback(arg, ARES_ENOMEM, 0, NULL, 0);
63 query->server_info = malloc(channel->nservers *
64 sizeof(query->server_info[0]));
65 if (!query->server_info)
69 callback(arg, ARES_ENOMEM, 0, NULL, 0);
73 /* Compute the query ID. Start with no timeout. */
74 query->qid = DNS_HEADER_QID(qbuf);
75 query->timeout.tv_sec = 0;
76 query->timeout.tv_usec = 0;
78 /* Form the TCP query buffer by prepending qlen (as two
79 * network-order bytes) to qbuf.
81 query->tcpbuf[0] = (unsigned char)((qlen >> 8) & 0xff);
82 query->tcpbuf[1] = (unsigned char)(qlen & 0xff);
83 memcpy(query->tcpbuf + 2, qbuf, qlen);
84 query->tcplen = qlen + 2;
86 /* Fill in query arguments. */
87 query->qbuf = query->tcpbuf + 2;
89 query->callback = callback;
92 /* Initialize query status. */
95 /* Choose the server to send the query to. If rotation is enabled, keep track
96 * of the next server we want to use. */
97 query->server = channel->last_server;
98 if (channel->rotate == 1)
99 channel->last_server = (channel->last_server + 1) % channel->nservers;
101 for (i = 0; i < channel->nservers; i++)
103 query->server_info[i].skip_server = 0;
104 query->server_info[i].tcp_connection_generation = 0;
107 packetsz = (channel->flags & ARES_FLAG_EDNS) ? channel->ednspsz : PACKETSZ;
108 query->using_tcp = (channel->flags & ARES_FLAG_USEVC) || qlen > packetsz;
110 query->error_status = ARES_ECONNREFUSED;
113 /* Initialize our list nodes. */
114 ares__init_list_node(&(query->queries_by_qid), query);
115 ares__init_list_node(&(query->queries_by_timeout), query);
116 ares__init_list_node(&(query->queries_to_server), query);
117 ares__init_list_node(&(query->all_queries), query);
119 /* Chain the query into the list of all queries. */
120 ares__insert_in_list(&(query->all_queries), &(channel->all_queries));
121 /* Keep track of queries bucketed by qid, so we can process DNS
124 ares__insert_in_list(
125 &(query->queries_by_qid),
126 &(channel->queries_by_qid[query->qid % ARES_QID_TABLE_SIZE]));
128 /* Perform the first query action. */
130 ares__send_query(channel, query, &now);