1 /* MIT License
2 *
3 * Copyright (c) 2023 Brad House
4 *
5 * Permission is hereby granted, free of charge, to any person obtaining a copy
6 * of this software and associated documentation files (the "Software"), to deal
7 * in the Software without restriction, including without limitation the rights
8 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
9 * copies of the Software, and to permit persons to whom the Software is
10 * furnished to do so, subject to the following conditions:
11 *
12 * The above copyright notice and this permission notice (including the next
13 * paragraph) shall be included in all copies or substantial portions of the
14 * Software.
15 *
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
19 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
21 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
22 * SOFTWARE.
23 *
24 * SPDX-License-Identifier: MIT
25 */
26
27 #include "ares_setup.h"
28 #include "ares.h"
29 #include "ares_private.h"
30
ares_create_query(const char * name,int dnsclass,int type,unsigned short id,int rd,unsigned char ** bufp,int * buflenp,int max_udp_size)31 int ares_create_query(const char *name, int dnsclass, int type,
32 unsigned short id, int rd, unsigned char **bufp,
33 int *buflenp, int max_udp_size)
34 {
35 ares_status_t status;
36 ares_dns_record_t *dnsrec = NULL;
37 size_t len;
38
39 if (name == NULL || bufp == NULL || buflenp == NULL) {
40 status = ARES_EFORMERR;
41 goto done;
42 }
43
44 *bufp = NULL;
45 *buflenp = 0;
46
47 /* Per RFC 7686, reject queries for ".onion" domain names with NXDOMAIN. */
48 if (ares__is_onion_domain(name)) {
49 status = ARES_ENOTFOUND;
50 goto done;
51 }
52
53 status = ares_dns_record_create(&dnsrec, id, rd ? ARES_FLAG_RD : 0,
54 ARES_OPCODE_QUERY, ARES_RCODE_NOERROR);
55 if (status != ARES_SUCCESS) {
56 goto done;
57 }
58
59 status = ares_dns_record_query_add(dnsrec, name, (ares_dns_rec_type_t)type,
60 (ares_dns_class_t)dnsclass);
61 if (status != ARES_SUCCESS) {
62 goto done;
63 }
64
65 /* max_udp_size > 0 indicates EDNS, so send OPT RR as an additional record */
66 if (max_udp_size > 0) {
67 ares_dns_rr_t *rr = NULL;
68
69 status = ares_dns_record_rr_add(&rr, dnsrec, ARES_SECTION_ADDITIONAL, "",
70 ARES_REC_TYPE_OPT, ARES_CLASS_IN, 0);
71 if (status != ARES_SUCCESS) {
72 goto done;
73 }
74
75 if (max_udp_size > 65535) {
76 status = ARES_EFORMERR;
77 goto done;
78 }
79
80 status = ares_dns_rr_set_u16(rr, ARES_RR_OPT_UDP_SIZE,
81 (unsigned short)max_udp_size);
82 if (status != ARES_SUCCESS) {
83 goto done;
84 }
85
86 status = ares_dns_rr_set_u8(rr, ARES_RR_OPT_VERSION, 0);
87 if (status != ARES_SUCCESS) {
88 goto done;
89 }
90
91 status = ares_dns_rr_set_u16(rr, ARES_RR_OPT_FLAGS, 0);
92 if (status != ARES_SUCCESS) {
93 goto done;
94 }
95 }
96
97 status = ares_dns_write(dnsrec, bufp, &len);
98 if (status != ARES_SUCCESS) {
99 goto done;
100 }
101
102 *buflenp = (int)len;
103
104 done:
105 ares_dns_record_destroy(dnsrec);
106 return (int)status;
107 }
108