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_private.h"
28 #include "ares_data.h"
29
ares_parse_mx_reply(const unsigned char * abuf,int alen_int,struct ares_mx_reply ** mx_out)30 int ares_parse_mx_reply(const unsigned char *abuf, int alen_int,
31 struct ares_mx_reply **mx_out)
32 {
33 ares_status_t status;
34 size_t alen;
35 struct ares_mx_reply *mx_head = NULL;
36 struct ares_mx_reply *mx_last = NULL;
37 struct ares_mx_reply *mx_curr;
38 ares_dns_record_t *dnsrec = NULL;
39 size_t i;
40
41 *mx_out = NULL;
42
43 if (alen_int < 0) {
44 return ARES_EBADRESP;
45 }
46
47 alen = (size_t)alen_int;
48
49 status = ares_dns_parse(abuf, alen, 0, &dnsrec);
50 if (status != ARES_SUCCESS) {
51 goto done;
52 }
53
54 if (ares_dns_record_rr_cnt(dnsrec, ARES_SECTION_ANSWER) == 0) {
55 status = ARES_ENODATA;
56 goto done;
57 }
58
59 for (i = 0; i < ares_dns_record_rr_cnt(dnsrec, ARES_SECTION_ANSWER); i++) {
60 const ares_dns_rr_t *rr =
61 ares_dns_record_rr_get(dnsrec, ARES_SECTION_ANSWER, i);
62
63 if (rr == NULL) {
64 /* Shouldn't be possible */
65 status = ARES_EBADRESP; /* LCOV_EXCL_LINE: DefensiveCoding */
66 goto done; /* LCOV_EXCL_LINE: DefensiveCoding */
67 }
68
69 if (ares_dns_rr_get_class(rr) != ARES_CLASS_IN ||
70 ares_dns_rr_get_type(rr) != ARES_REC_TYPE_MX) {
71 continue;
72 }
73
74 /* Allocate storage for this MX answer appending it to the list */
75 mx_curr = ares_malloc_data(ARES_DATATYPE_MX_REPLY);
76 if (mx_curr == NULL) {
77 status = ARES_ENOMEM; /* LCOV_EXCL_LINE: OutOfMemory */
78 goto done; /* LCOV_EXCL_LINE: OutOfMemory */
79 }
80
81 /* Link in the record */
82 if (mx_last) {
83 mx_last->next = mx_curr;
84 } else {
85 mx_head = mx_curr;
86 }
87 mx_last = mx_curr;
88
89 mx_curr->priority = ares_dns_rr_get_u16(rr, ARES_RR_MX_PREFERENCE);
90 mx_curr->host = ares_strdup(ares_dns_rr_get_str(rr, ARES_RR_MX_EXCHANGE));
91
92 if (mx_curr->host == NULL) {
93 status = ARES_ENOMEM; /* LCOV_EXCL_LINE: OutOfMemory */
94 goto done; /* LCOV_EXCL_LINE: OutOfMemory */
95 }
96 }
97
98 done:
99 /* clean up on error */
100 if (status != ARES_SUCCESS) {
101 if (mx_head) {
102 ares_free_data(mx_head);
103 }
104 } else {
105 /* everything looks fine, return the data */
106 *mx_out = mx_head;
107 }
108 ares_dns_record_destroy(dnsrec);
109 return (int)status;
110 }
111