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_SYS_SOCKET_H
20 # include <sys/socket.h>
21 #endif
22 #ifdef HAVE_NETINET_IN_H
23 # include <netinet/in.h>
24 #endif
25 #ifdef HAVE_ARPA_NAMESER_H
26 # include <arpa/nameser.h>
27 #else
28 # include "nameser.h"
29 #endif
30 #ifdef HAVE_ARPA_NAMESER_COMPAT_H
31 # include <arpa/nameser_compat.h>
32 #endif
33
34 #include <stdlib.h>
35 #include <string.h>
36 #include <time.h>
37 #include "ares.h"
38 #include "ares_dns.h"
39 #include "ares_private.h"
40
ares_send(ares_channel channel,const unsigned char * qbuf,int qlen,ares_callback callback,void * arg)41 void ares_send(ares_channel channel, const unsigned char *qbuf, int qlen,
42 ares_callback callback, void *arg)
43 {
44 struct query *query;
45 int i;
46 struct timeval now;
47
48 /* Verify that the query is at least long enough to hold the header. */
49 if (qlen < HFIXEDSZ || qlen >= (1 << 16))
50 {
51 callback(arg, ARES_EBADQUERY, 0, NULL, 0);
52 return;
53 }
54
55 /* Allocate space for query and allocated fields. */
56 query = malloc(sizeof(struct query));
57 if (!query)
58 {
59 callback(arg, ARES_ENOMEM, 0, NULL, 0);
60 return;
61 }
62 query->tcpbuf = malloc(qlen + 2);
63 if (!query->tcpbuf)
64 {
65 free(query);
66 callback(arg, ARES_ENOMEM, 0, NULL, 0);
67 return;
68 }
69 query->server_info = malloc(channel->nservers *
70 sizeof(query->server_info[0]));
71 if (!query->server_info)
72 {
73 free(query->tcpbuf);
74 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 = (unsigned short)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 query->using_tcp = (channel->flags & ARES_FLAG_USEVC) || qlen > PACKETSZ;
113 query->error_status = ARES_ECONNREFUSED;
114 query->timeouts = 0;
115
116 /* Initialize our list nodes. */
117 ares__init_list_node(&(query->queries_by_qid), query);
118 ares__init_list_node(&(query->queries_by_timeout), query);
119 ares__init_list_node(&(query->queries_to_server), query);
120 ares__init_list_node(&(query->all_queries), query);
121
122 /* Chain the query into the list of all queries. */
123 ares__insert_in_list(&(query->all_queries), &(channel->all_queries));
124 /* Keep track of queries bucketed by qid, so we can process DNS
125 * responses quickly.
126 */
127 ares__insert_in_list(
128 &(query->queries_by_qid),
129 &(channel->queries_by_qid[query->qid % ARES_QID_TABLE_SIZE]));
130
131 /* Perform the first query action. */
132 now = ares__tvnow();
133 ares__send_query(channel, query, &now);
134 }
135