1
2 /* Copyright 1998 by the Massachusetts Institute of Technology.
3 *
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.
15 */
16
17 #include "ares_setup.h"
18
19 #ifdef HAVE_NETINET_IN_H
20 # include <netinet/in.h>
21 #endif
22 #ifdef HAVE_ARPA_NAMESER_H
23 # include <arpa/nameser.h>
24 #else
25 # include "nameser.h"
26 #endif
27 #ifdef HAVE_ARPA_NAMESER_COMPAT_H
28 # include <arpa/nameser_compat.h>
29 #endif
30
31 #include "ares.h"
32 #include "ares_dns.h"
33 #include "ares_private.h"
34
ares_send(ares_channel channel,const unsigned char * qbuf,int qlen,ares_callback callback,void * arg)35 void ares_send(ares_channel channel, const unsigned char *qbuf, int qlen,
36 ares_callback callback, void *arg)
37 {
38 struct query *query;
39 int i, packetsz;
40 struct timeval now;
41
42 /* Verify that the query is at least long enough to hold the header. */
43 if (qlen < HFIXEDSZ || qlen >= (1 << 16))
44 {
45 callback(arg, ARES_EBADQUERY, 0, NULL, 0);
46 return;
47 }
48
49 /* Allocate space for query and allocated fields. */
50 query = ares_malloc(sizeof(struct query));
51 if (!query)
52 {
53 callback(arg, ARES_ENOMEM, 0, NULL, 0);
54 return;
55 }
56 query->tcpbuf = ares_malloc(qlen + 2);
57 if (!query->tcpbuf)
58 {
59 ares_free(query);
60 callback(arg, ARES_ENOMEM, 0, NULL, 0);
61 return;
62 }
63 if (channel->nservers < 1)
64 {
65 ares_free(query);
66 callback(arg, ARES_ESERVFAIL, 0, NULL, 0);
67 return;
68 }
69 query->server_info = ares_malloc(channel->nservers *
70 sizeof(query->server_info[0]));
71 if (!query->server_info)
72 {
73 ares_free(query->tcpbuf);
74 ares_free(query);
75 callback(arg, ARES_ENOMEM, 0, NULL, 0);
76 return;
77 }
78
79 /* Compute the query ID. Start with no timeout. */
80 query->qid = DNS_HEADER_QID(qbuf);
81 query->timeout.tv_sec = 0;
82 query->timeout.tv_usec = 0;
83
84 /* Form the TCP query buffer by prepending qlen (as two
85 * network-order bytes) to qbuf.
86 */
87 query->tcpbuf[0] = (unsigned char)((qlen >> 8) & 0xff);
88 query->tcpbuf[1] = (unsigned char)(qlen & 0xff);
89 memcpy(query->tcpbuf + 2, qbuf, qlen);
90 query->tcplen = qlen + 2;
91
92 /* Fill in query arguments. */
93 query->qbuf = query->tcpbuf + 2;
94 query->qlen = qlen;
95 query->callback = callback;
96 query->arg = arg;
97
98 /* Initialize query status. */
99 query->try_count = 0;
100
101 /* Choose the server to send the query to. If rotation is enabled, keep track
102 * of the next server we want to use. */
103 query->server = channel->last_server;
104 if (channel->rotate == 1)
105 channel->last_server = (channel->last_server + 1) % channel->nservers;
106
107 for (i = 0; i < channel->nservers; i++)
108 {
109 query->server_info[i].skip_server = 0;
110 query->server_info[i].tcp_connection_generation = 0;
111 }
112
113 packetsz = (channel->flags & ARES_FLAG_EDNS) ? channel->ednspsz : PACKETSZ;
114 query->using_tcp = (channel->flags & ARES_FLAG_USEVC) || qlen > packetsz;
115
116 query->error_status = ARES_ECONNREFUSED;
117 query->timeouts = 0;
118
119 /* Initialize our list nodes. */
120 ares__init_list_node(&(query->queries_by_qid), query);
121 ares__init_list_node(&(query->queries_by_timeout), query);
122 ares__init_list_node(&(query->queries_to_server), query);
123 ares__init_list_node(&(query->all_queries), query);
124
125 /* Chain the query into the list of all queries. */
126 ares__insert_in_list(&(query->all_queries), &(channel->all_queries));
127 /* Keep track of queries bucketed by qid, so we can process DNS
128 * responses quickly.
129 */
130 ares__insert_in_list(
131 &(query->queries_by_qid),
132 &(channel->queries_by_qid[query->qid % ARES_QID_TABLE_SIZE]));
133
134 /* Perform the first query action. */
135 now = ares__tvnow();
136 ares__send_query(channel, query, &now);
137 }
138