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
29 #ifdef HAVE_NETINET_IN_H
30 # include <netinet/in.h>
31 #endif
32 #ifdef HAVE_NETDB_H
33 # include <netdb.h>
34 #endif
35
36 #include "ares.h"
37 #include "ares_private.h"
38
ares_parse_ptr_reply(const unsigned char * abuf,int alen_int,const void * addr,int addrlen,int family,struct hostent ** host)39 int ares_parse_ptr_reply(const unsigned char *abuf, int alen_int,
40 const void *addr, int addrlen, int family,
41 struct hostent **host)
42 {
43 ares_status_t status;
44 size_t alen;
45 size_t ptrcount = 0;
46 struct hostent *hostent = NULL;
47 const char *hostname = NULL;
48 const char *ptrname = NULL;
49 ares_dns_record_t *dnsrec = NULL;
50 size_t i;
51 size_t ancount;
52
53 *host = NULL;
54
55 if (alen_int < 0) {
56 return ARES_EBADRESP;
57 }
58
59 alen = (size_t)alen_int;
60
61 status = ares_dns_parse(abuf, alen, 0, &dnsrec);
62 if (status != ARES_SUCCESS) {
63 goto done;
64 }
65
66 /* Fetch name from query as we will use it to compare later on. Old code
67 * did this check, so we'll retain it. */
68 status = ares_dns_record_query_get(dnsrec, 0, &ptrname, NULL, NULL);
69 if (status != ARES_SUCCESS) {
70 goto done;
71 }
72
73 ancount = ares_dns_record_rr_cnt(dnsrec, ARES_SECTION_ANSWER);
74 if (ancount == 0) {
75 status = ARES_ENODATA;
76 goto done;
77 }
78
79 /* Response structure */
80 hostent = ares_malloc(sizeof(*hostent));
81 if (hostent == NULL) {
82 status = ARES_ENOMEM;
83 goto done;
84 }
85
86 memset(hostent, 0, sizeof(*hostent));
87
88 hostent->h_addr_list = ares_malloc(2 * sizeof(*hostent->h_addr_list));
89 if (hostent->h_addr_list == NULL) {
90 status = ARES_ENOMEM;
91 goto done;
92 }
93 memset(hostent->h_addr_list, 0, 2 * sizeof(*hostent->h_addr_list));
94 if (addr != NULL && addrlen > 0) {
95 hostent->h_addr_list[0] = ares_malloc((size_t)addrlen);
96 if (hostent->h_addr_list[0] == NULL) {
97 status = ARES_ENOMEM;
98 goto done;
99 }
100 memcpy(hostent->h_addr_list[0], addr, (size_t)addrlen);
101 }
102 hostent->h_addrtype = (HOSTENT_ADDRTYPE_TYPE)family;
103 hostent->h_length = (HOSTENT_LENGTH_TYPE)addrlen;
104
105 /* Preallocate the maximum number + 1 */
106 hostent->h_aliases = ares_malloc((ancount + 1) * sizeof(*hostent->h_aliases));
107 if (hostent->h_aliases == NULL) {
108 status = ARES_ENOMEM;
109 goto done;
110 }
111 memset(hostent->h_aliases, 0, (ancount + 1) * sizeof(*hostent->h_aliases));
112
113
114 /* Cycle through answers */
115 for (i = 0; i < ancount; i++) {
116 const ares_dns_rr_t *rr =
117 ares_dns_record_rr_get(dnsrec, ARES_SECTION_ANSWER, i);
118
119 if (rr == NULL) {
120 /* Shouldn't be possible */
121 status = ARES_EBADRESP;
122 goto done;
123 }
124
125 if (ares_dns_rr_get_class(rr) != ARES_CLASS_IN) {
126 continue;
127 }
128
129 /* Any time we see a CNAME, replace our ptrname with its value */
130 if (ares_dns_rr_get_type(rr) == ARES_REC_TYPE_CNAME) {
131 ptrname = ares_dns_rr_get_str(rr, ARES_RR_CNAME_CNAME);
132 if (ptrname == NULL) {
133 status = ARES_EBADRESP;
134 goto done;
135 }
136 }
137
138 /* Handling for PTR records below this, otherwise skip */
139 if (ares_dns_rr_get_type(rr) != ARES_REC_TYPE_PTR) {
140 continue;
141 }
142
143 /* Issue #683
144 * Old code compared the name in the rr to the ptrname, but I think this
145 * is wrong since it was proven wrong for A & AAAA records. Leaving
146 * this code commented out for future reference
147 *
148 * rname = ares_dns_rr_get_name(rr);
149 * if (rname == NULL) {
150 * status = ARES_EBADRESP;
151 * goto done;
152 * }
153 * if (strcasecmp(ptrname, rname) != 0) {
154 * continue;
155 * }
156 */
157
158 /* Save most recent PTR record as the hostname */
159 hostname = ares_dns_rr_get_str(rr, ARES_RR_PTR_DNAME);
160 if (hostname == NULL) {
161 status = ARES_EBADRESP;
162 goto done;
163 }
164
165 /* Append as an alias */
166 hostent->h_aliases[ptrcount] = ares_strdup(hostname);
167 if (hostent->h_aliases[ptrcount] == NULL) {
168 status = ARES_ENOMEM;
169 goto done;
170 }
171 ptrcount++;
172 }
173
174 if (ptrcount == 0) {
175 status = ARES_ENODATA;
176 goto done;
177 } else {
178 status = ARES_SUCCESS;
179 }
180
181 /* Fill in hostname */
182 hostent->h_name = ares_strdup(hostname);
183 if (hostent->h_name == NULL) {
184 status = ARES_ENOMEM;
185 goto done;
186 }
187
188 done:
189 if (status != ARES_SUCCESS) {
190 ares_free_hostent(hostent);
191 /* Compatibility */
192 if (status == ARES_EBADNAME) {
193 status = ARES_EBADRESP;
194 }
195 } else {
196 *host = hostent;
197 }
198 ares_dns_record_destroy(dnsrec);
199 return (int)status;
200 }
201