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
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
ares_parse_ptr_reply_dnsrec(const ares_dns_record_t * dnsrec,const void * addr,int addrlen,int family,struct hostent ** host)37 ares_status_t ares_parse_ptr_reply_dnsrec(const ares_dns_record_t *dnsrec,
38 const void *addr, int addrlen,
39 int family, struct hostent **host)
40 {
41 ares_status_t status;
42 size_t ptrcount = 0;
43 struct hostent *hostent = NULL;
44 const char *hostname = NULL;
45 const char *ptrname = NULL;
46 size_t i;
47 size_t ancount;
48
49 *host = NULL;
50
51 /* Fetch name from query as we will use it to compare later on. Old code
52 * did this check, so we'll retain it. */
53 status = ares_dns_record_query_get(dnsrec, 0, &ptrname, NULL, NULL);
54 if (status != ARES_SUCCESS) {
55 goto done;
56 }
57
58 ancount = ares_dns_record_rr_cnt(dnsrec, ARES_SECTION_ANSWER);
59 if (ancount == 0) {
60 status = ARES_ENODATA;
61 goto done;
62 }
63
64 /* Response structure */
65 hostent = ares_malloc(sizeof(*hostent));
66 if (hostent == NULL) {
67 status = ARES_ENOMEM;
68 goto done;
69 }
70
71 memset(hostent, 0, sizeof(*hostent));
72
73 hostent->h_addr_list = ares_malloc(2 * sizeof(*hostent->h_addr_list));
74 if (hostent->h_addr_list == NULL) {
75 status = ARES_ENOMEM;
76 goto done;
77 }
78 memset(hostent->h_addr_list, 0, 2 * sizeof(*hostent->h_addr_list));
79 if (addr != NULL && addrlen > 0) {
80 hostent->h_addr_list[0] = ares_malloc((size_t)addrlen);
81 if (hostent->h_addr_list[0] == NULL) {
82 status = ARES_ENOMEM;
83 goto done;
84 }
85 memcpy(hostent->h_addr_list[0], addr, (size_t)addrlen);
86 }
87 hostent->h_addrtype = (HOSTENT_ADDRTYPE_TYPE)family;
88 hostent->h_length = (HOSTENT_LENGTH_TYPE)addrlen;
89
90 /* Preallocate the maximum number + 1 */
91 hostent->h_aliases = ares_malloc((ancount + 1) * sizeof(*hostent->h_aliases));
92 if (hostent->h_aliases == NULL) {
93 status = ARES_ENOMEM;
94 goto done;
95 }
96 memset(hostent->h_aliases, 0, (ancount + 1) * sizeof(*hostent->h_aliases));
97
98
99 /* Cycle through answers */
100 for (i = 0; i < ancount; i++) {
101 const ares_dns_rr_t *rr =
102 ares_dns_record_rr_get_const(dnsrec, ARES_SECTION_ANSWER, i);
103
104 if (rr == NULL) {
105 /* Shouldn't be possible */
106 status = ARES_EBADRESP; /* LCOV_EXCL_LINE: DefensiveCoding */
107 goto done; /* LCOV_EXCL_LINE: DefensiveCoding */
108 }
109
110 if (ares_dns_rr_get_class(rr) != ARES_CLASS_IN) {
111 continue;
112 }
113
114 /* Any time we see a CNAME, replace our ptrname with its value */
115 if (ares_dns_rr_get_type(rr) == ARES_REC_TYPE_CNAME) {
116 ptrname = ares_dns_rr_get_str(rr, ARES_RR_CNAME_CNAME);
117 if (ptrname == NULL) {
118 status = ARES_EBADRESP; /* LCOV_EXCL_LINE: DefensiveCoding */
119 goto done; /* LCOV_EXCL_LINE: DefensiveCoding */
120 }
121 }
122
123 /* Handling for PTR records below this, otherwise skip */
124 if (ares_dns_rr_get_type(rr) != ARES_REC_TYPE_PTR) {
125 continue;
126 }
127
128 /* Issue #683
129 * Old code compared the name in the rr to the ptrname, but I think this
130 * is wrong since it was proven wrong for A & AAAA records. Leaving
131 * this code commented out for future reference
132 *
133 * rname = ares_dns_rr_get_name(rr);
134 * if (rname == NULL) {
135 * status = ARES_EBADRESP;
136 * goto done;
137 * }
138 * if (!ares_strcaseeq(ptrname, rname)) {
139 * continue;
140 * }
141 */
142
143 /* Save most recent PTR record as the hostname */
144 hostname = ares_dns_rr_get_str(rr, ARES_RR_PTR_DNAME);
145 if (hostname == NULL) {
146 status = ARES_EBADRESP; /* LCOV_EXCL_LINE: DefensiveCoding */
147 goto done; /* LCOV_EXCL_LINE: DefensiveCoding */
148 }
149
150 /* Append as an alias */
151 hostent->h_aliases[ptrcount] = ares_strdup(hostname);
152 if (hostent->h_aliases[ptrcount] == NULL) {
153 status = ARES_ENOMEM;
154 goto done;
155 }
156 ptrcount++;
157 }
158
159 if (ptrcount == 0) {
160 status = ARES_ENODATA;
161 goto done;
162 } else {
163 status = ARES_SUCCESS;
164 }
165
166 /* Fill in hostname */
167 hostent->h_name = ares_strdup(hostname);
168 if (hostent->h_name == NULL) {
169 status = ARES_ENOMEM; /* LCOV_EXCL_LINE: OutOfMemory */
170 goto done; /* LCOV_EXCL_LINE: OutOfMemory */
171 }
172
173 done:
174 if (status != ARES_SUCCESS) {
175 ares_free_hostent(hostent);
176 /* Compatibility */
177 if (status == ARES_EBADNAME) {
178 status = ARES_EBADRESP;
179 }
180 } else {
181 *host = hostent;
182 }
183 return status;
184 }
185
ares_parse_ptr_reply(const unsigned char * abuf,int alen_int,const void * addr,int addrlen,int family,struct hostent ** host)186 int ares_parse_ptr_reply(const unsigned char *abuf, int alen_int,
187 const void *addr, int addrlen, int family,
188 struct hostent **host)
189 {
190 size_t alen;
191 ares_dns_record_t *dnsrec = NULL;
192 ares_status_t status;
193
194 if (alen_int < 0) {
195 return ARES_EBADRESP;
196 }
197
198 alen = (size_t)alen_int;
199
200 status = ares_dns_parse(abuf, alen, 0, &dnsrec);
201 if (status != ARES_SUCCESS) {
202 goto done;
203 }
204
205 status = ares_parse_ptr_reply_dnsrec(dnsrec, addr, addrlen, family, host);
206
207 done:
208 ares_dns_record_destroy(dnsrec);
209 if (status == ARES_EBADNAME) {
210 status = ARES_EBADRESP;
211 }
212 return (int)status;
213 }
214