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_caa_reply(const unsigned char * abuf,int alen_int,struct ares_caa_reply ** caa_out)30 int ares_parse_caa_reply(const unsigned char *abuf, int alen_int,
31 struct ares_caa_reply **caa_out)
32 {
33 ares_status_t status;
34 size_t alen;
35 struct ares_caa_reply *caa_head = NULL;
36 struct ares_caa_reply *caa_last = NULL;
37 struct ares_caa_reply *caa_curr;
38 ares_dns_record_t *dnsrec = NULL;
39 size_t i;
40
41 *caa_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 unsigned char *ptr;
61 size_t ptr_len;
62 const ares_dns_rr_t *rr =
63 ares_dns_record_rr_get(dnsrec, ARES_SECTION_ANSWER, i);
64
65 if (rr == NULL) {
66 /* Shouldn't be possible */
67 status = ARES_EBADRESP; /* LCOV_EXCL_LINE: DefensiveCoding */
68 goto done; /* LCOV_EXCL_LINE: DefensiveCoding */
69 }
70
71 /* XXX: Why do we allow Chaos class? */
72 if (ares_dns_rr_get_class(rr) != ARES_CLASS_IN &&
73 ares_dns_rr_get_class(rr) != ARES_CLASS_CHAOS) {
74 continue;
75 }
76
77 /* Only looking for CAA records */
78 if (ares_dns_rr_get_type(rr) != ARES_REC_TYPE_CAA) {
79 continue;
80 }
81
82 /* Allocate storage for this CAA answer appending it to the list */
83 caa_curr = ares_malloc_data(ARES_DATATYPE_CAA_REPLY);
84 if (caa_curr == NULL) {
85 status = ARES_ENOMEM; /* LCOV_EXCL_LINE: OutOfMemory */
86 goto done; /* LCOV_EXCL_LINE: OutOfMemory */
87 }
88
89 /* Link in the record */
90 if (caa_last) {
91 caa_last->next = caa_curr;
92 } else {
93 caa_head = caa_curr;
94 }
95 caa_last = caa_curr;
96
97 caa_curr->critical = ares_dns_rr_get_u8(rr, ARES_RR_CAA_CRITICAL);
98 caa_curr->property =
99 (unsigned char *)ares_strdup(ares_dns_rr_get_str(rr, ARES_RR_CAA_TAG));
100 if (caa_curr->property == NULL) {
101 status = ARES_ENOMEM; /* LCOV_EXCL_LINE: OutOfMemory */
102 break; /* LCOV_EXCL_LINE: OutOfMemory */
103 }
104 /* RFC6844 says this can only be ascii, so not sure why we're recording a
105 * length */
106 caa_curr->plength = ares_strlen((const char *)caa_curr->property);
107
108 ptr = ares_dns_rr_get_bin(rr, ARES_RR_CAA_VALUE, &ptr_len);
109 if (ptr == NULL) {
110 status = ARES_EBADRESP; /* LCOV_EXCL_LINE: DefensiveCoding */
111 goto done; /* LCOV_EXCL_LINE: DefensiveCoding */
112 }
113
114 /* Wants NULL termination for some reason */
115 caa_curr->value = ares_malloc(ptr_len + 1);
116 if (caa_curr->value == NULL) {
117 status = ARES_ENOMEM; /* LCOV_EXCL_LINE: OutOfMemory */
118 goto done; /* LCOV_EXCL_LINE: OutOfMemory */
119 }
120 memcpy(caa_curr->value, ptr, ptr_len);
121 caa_curr->value[ptr_len] = 0;
122 caa_curr->length = ptr_len;
123 }
124
125 done:
126 /* clean up on error */
127 if (status != ARES_SUCCESS) {
128 if (caa_head) {
129 ares_free_data(caa_head);
130 }
131 } else {
132 /* everything looks fine, return the data */
133 *caa_out = caa_head;
134 }
135 ares_dns_record_destroy(dnsrec);
136 return (int)status;
137 }
138