1 /* MIT License
2 *
3 * Copyright (c) 1998 Massachusetts Institute of Technology
4 * Copyright (c) The c-ares project and its contributors
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a copy
7 * of this software and associated documentation files (the "Software"), to deal
8 * in the Software without restriction, including without limitation the rights
9 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
10 * copies of the Software, and to permit persons to whom the Software is
11 * furnished to do so, subject to the following conditions:
12 *
13 * The above copyright notice and this permission notice (including the next
14 * paragraph) shall be included in all copies or substantial portions of the
15 * Software.
16 *
17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
20 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
21 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
22 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
23 * SOFTWARE.
24 *
25 * SPDX-License-Identifier: MIT
26 */
27
28 #include "ares_private.h"
29
30 #ifdef HAVE_NETINET_IN_H
31 # include <netinet/in.h>
32 #endif
33
34 #include "ares_nameser.h"
35
36 /* Simply decodes a length-encoded character string. The first byte of the
37 * input is the length of the string to be returned and the bytes thereafter
38 * are the characters of the string. The returned result will be NULL
39 * terminated.
40 */
ares_expand_string_ex(const unsigned char * encoded,const unsigned char * abuf,size_t alen,unsigned char ** s,size_t * enclen)41 ares_status_t ares_expand_string_ex(const unsigned char *encoded,
42 const unsigned char *abuf, size_t alen,
43 unsigned char **s, size_t *enclen)
44 {
45 ares_status_t status;
46 ares_buf_t *buf = NULL;
47 size_t start_len;
48 size_t len = 0;
49
50 if (encoded == NULL || abuf == NULL || alen == 0 || enclen == NULL) {
51 return ARES_EBADSTR; /* EFORMERR would be better */
52 }
53
54 if (encoded < abuf || encoded >= abuf + alen) {
55 return ARES_EBADSTR; /* EFORMERR would be better */
56 }
57
58 *enclen = 0;
59
60 /* NOTE: we allow 's' to be NULL to skip it */
61 if (s) {
62 *s = NULL;
63 }
64
65 buf = ares_buf_create_const(abuf, alen);
66
67 if (buf == NULL) {
68 return ARES_ENOMEM;
69 }
70
71 status = ares_buf_set_position(buf, (size_t)(encoded - abuf));
72 if (status != ARES_SUCCESS) {
73 goto done;
74 }
75
76 start_len = ares_buf_len(buf);
77 status = ares_buf_parse_dns_binstr(buf, ares_buf_len(buf), s, &len);
78 /* hrm, no way to pass back 'len' with the prototype */
79 if (status != ARES_SUCCESS) {
80 goto done;
81 }
82
83 *enclen = start_len - ares_buf_len(buf);
84
85 done:
86 ares_buf_destroy(buf);
87 if (status == ARES_EBADNAME || status == ARES_EBADRESP) {
88 status = ARES_EBADSTR;
89 }
90 return status;
91 }
92
ares_expand_string(const unsigned char * encoded,const unsigned char * abuf,int alen,unsigned char ** s,long * enclen)93 int ares_expand_string(const unsigned char *encoded, const unsigned char *abuf,
94 int alen, unsigned char **s, long *enclen)
95 {
96 ares_status_t status;
97 size_t temp_enclen = 0;
98
99 if (encoded == NULL || abuf == NULL || alen <= 0 || enclen == NULL) {
100 return ARES_EBADRESP;
101 }
102
103 status = ares_expand_string_ex(encoded, abuf, (size_t)alen, s, &temp_enclen);
104
105 *enclen = (long)temp_enclen;
106 return (int)status;
107 }
108