1 | /* Creation of DNS query packets. |
2 | Copyright (C) 1995-2019 Free Software Foundation, Inc. |
3 | This file is part of the GNU C Library. |
4 | |
5 | The GNU C Library is free software; you can redistribute it and/or |
6 | modify it under the terms of the GNU Lesser General Public |
7 | License as published by the Free Software Foundation; either |
8 | version 2.1 of the License, or (at your option) any later version. |
9 | |
10 | The GNU C Library is distributed in the hope that it will be useful, |
11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
13 | Lesser General Public License for more details. |
14 | |
15 | You should have received a copy of the GNU Lesser General Public |
16 | License along with the GNU C Library; if not, see |
17 | <http://www.gnu.org/licenses/>. */ |
18 | |
19 | /* |
20 | * Copyright (c) 1985, 1993 |
21 | * The Regents of the University of California. All rights reserved. |
22 | * |
23 | * Redistribution and use in source and binary forms, with or without |
24 | * modification, are permitted provided that the following conditions |
25 | * are met: |
26 | * 1. Redistributions of source code must retain the above copyright |
27 | * notice, this list of conditions and the following disclaimer. |
28 | * 2. Redistributions in binary form must reproduce the above copyright |
29 | * notice, this list of conditions and the following disclaimer in the |
30 | * documentation and/or other materials provided with the distribution. |
31 | * 4. Neither the name of the University nor the names of its contributors |
32 | * may be used to endorse or promote products derived from this software |
33 | * without specific prior written permission. |
34 | * |
35 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
36 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
37 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
38 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
39 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
40 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
41 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
42 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
43 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
44 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
45 | * SUCH DAMAGE. |
46 | */ |
47 | |
48 | /* |
49 | * Portions Copyright (c) 1993 by Digital Equipment Corporation. |
50 | * |
51 | * Permission to use, copy, modify, and distribute this software for any |
52 | * purpose with or without fee is hereby granted, provided that the above |
53 | * copyright notice and this permission notice appear in all copies, and that |
54 | * the name of Digital Equipment Corporation not be used in advertising or |
55 | * publicity pertaining to distribution of the document or software without |
56 | * specific, written prior permission. |
57 | * |
58 | * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL |
59 | * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES |
60 | * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL DIGITAL EQUIPMENT |
61 | * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL |
62 | * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR |
63 | * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS |
64 | * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS |
65 | * SOFTWARE. |
66 | */ |
67 | |
68 | /* |
69 | * Portions Copyright (c) 1996-1999 by Internet Software Consortium. |
70 | * |
71 | * Permission to use, copy, modify, and distribute this software for any |
72 | * purpose with or without fee is hereby granted, provided that the above |
73 | * copyright notice and this permission notice appear in all copies. |
74 | * |
75 | * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS |
76 | * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES |
77 | * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE |
78 | * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL |
79 | * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR |
80 | * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS |
81 | * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS |
82 | * SOFTWARE. |
83 | */ |
84 | |
85 | #include <stdint.h> |
86 | #include <sys/types.h> |
87 | #include <sys/param.h> |
88 | #include <netinet/in.h> |
89 | #include <arpa/nameser.h> |
90 | #include <netdb.h> |
91 | #include <resolv/resolv-internal.h> |
92 | #include <resolv/resolv_context.h> |
93 | #include <string.h> |
94 | #include <sys/time.h> |
95 | #include <shlib-compat.h> |
96 | #include <random-bits.h> |
97 | |
98 | int |
99 | __res_context_mkquery (struct resolv_context *ctx, int op, const char *dname, |
100 | int class, int type, const unsigned char *data, |
101 | unsigned char *buf, int buflen) |
102 | { |
103 | HEADER *hp; |
104 | unsigned char *cp; |
105 | int n; |
106 | unsigned char *dnptrs[20], **dpp, **lastdnptr; |
107 | |
108 | if (class < 0 || class > 65535 || type < 0 || type > 65535) |
109 | return -1; |
110 | |
111 | /* Initialize header fields. */ |
112 | if ((buf == NULL) || (buflen < HFIXEDSZ)) |
113 | return -1; |
114 | memset (buf, 0, HFIXEDSZ); |
115 | hp = (HEADER *) buf; |
116 | /* We randomize the IDs every time. The old code just incremented |
117 | by one after the initial randomization which still predictable if |
118 | the application does multiple requests. */ |
119 | hp->id = random_bits (); |
120 | hp->opcode = op; |
121 | hp->rd = (ctx->resp->options & RES_RECURSE) != 0; |
122 | hp->rcode = NOERROR; |
123 | cp = buf + HFIXEDSZ; |
124 | buflen -= HFIXEDSZ; |
125 | dpp = dnptrs; |
126 | *dpp++ = buf; |
127 | *dpp++ = NULL; |
128 | lastdnptr = dnptrs + sizeof dnptrs / sizeof dnptrs[0]; |
129 | |
130 | /* Perform opcode specific processing. */ |
131 | switch (op) |
132 | { |
133 | case NS_NOTIFY_OP: |
134 | if ((buflen -= QFIXEDSZ + (data == NULL ? 0 : RRFIXEDSZ)) < 0) |
135 | return -1; |
136 | goto compose; |
137 | |
138 | case QUERY: |
139 | if ((buflen -= QFIXEDSZ) < 0) |
140 | return -1; |
141 | compose: |
142 | n = ns_name_compress (dname, cp, buflen, |
143 | (const unsigned char **) dnptrs, |
144 | (const unsigned char **) lastdnptr); |
145 | if (n < 0) |
146 | return -1; |
147 | cp += n; |
148 | buflen -= n; |
149 | NS_PUT16 (type, cp); |
150 | NS_PUT16 (class, cp); |
151 | hp->qdcount = htons (1); |
152 | if (op == QUERY || data == NULL) |
153 | break; |
154 | |
155 | /* Make an additional record for completion domain. */ |
156 | n = ns_name_compress ((char *)data, cp, buflen, |
157 | (const unsigned char **) dnptrs, |
158 | (const unsigned char **) lastdnptr); |
159 | if (__glibc_unlikely (n < 0)) |
160 | return -1; |
161 | cp += n; |
162 | buflen -= n; |
163 | NS_PUT16 (T_NULL, cp); |
164 | NS_PUT16 (class, cp); |
165 | NS_PUT32 (0, cp); |
166 | NS_PUT16 (0, cp); |
167 | hp->arcount = htons (1); |
168 | break; |
169 | |
170 | default: |
171 | return -1; |
172 | } |
173 | return cp - buf; |
174 | } |
175 | |
176 | /* Common part of res_nmkquery and res_mkquery. */ |
177 | static int |
178 | context_mkquery_common (struct resolv_context *ctx, |
179 | int op, const char *dname, int class, int type, |
180 | const unsigned char *data, |
181 | unsigned char *buf, int buflen) |
182 | { |
183 | if (ctx == NULL) |
184 | return -1; |
185 | int result = __res_context_mkquery |
186 | (ctx, op, dname, class, type, data, buf, buflen); |
187 | if (result >= 2) |
188 | memcpy (&ctx->resp->id, buf, 2); |
189 | __resolv_context_put (ctx); |
190 | return result; |
191 | } |
192 | |
193 | /* Form all types of queries. Returns the size of the result or -1 on |
194 | error. |
195 | |
196 | STATP points to an initialized resolver state. OP is the opcode of |
197 | the query. DNAME is the domain. CLASS and TYPE are the DNS query |
198 | class and type. DATA can be NULL; otherwise, it is a pointer to a |
199 | domain name which is included in the generated packet (if op == |
200 | NS_NOTIFY_OP). BUF must point to the out buffer of BUFLEN bytes. |
201 | |
202 | DATALEN and NEWRR_IN are currently ignored. */ |
203 | int |
204 | res_nmkquery (res_state statp, int op, const char *dname, |
205 | int class, int type, |
206 | const unsigned char *data, int datalen, |
207 | const unsigned char *newrr_in, |
208 | unsigned char *buf, int buflen) |
209 | { |
210 | return context_mkquery_common |
211 | (__resolv_context_get_override (statp), |
212 | op, dname, class, type, data, buf, buflen); |
213 | } |
214 | |
215 | int |
216 | res_mkquery (int op, const char *dname, int class, int type, |
217 | const unsigned char *data, int datalen, |
218 | const unsigned char *newrr_in, |
219 | unsigned char *buf, int buflen) |
220 | { |
221 | return context_mkquery_common |
222 | (__resolv_context_get_preinit (), |
223 | op, dname, class, type, data, buf, buflen); |
224 | } |
225 | |
226 | /* Create an OPT resource record. Return the length of the final |
227 | packet, or -1 on error. |
228 | |
229 | STATP must be an initialized resolver state. N0 is the current |
230 | number of bytes of the packet (already written to BUF by the |
231 | aller). BUF is the packet being constructed. The array it |
232 | pointers to must be BUFLEN bytes long. ANSLEN is the advertised |
233 | EDNS buffer size (to be included in the OPT resource record). */ |
234 | int |
235 | __res_nopt (struct resolv_context *ctx, |
236 | int n0, unsigned char *buf, int buflen, int anslen) |
237 | { |
238 | uint16_t flags = 0; |
239 | HEADER *hp = (HEADER *) buf; |
240 | unsigned char *cp = buf + n0; |
241 | unsigned char *ep = buf + buflen; |
242 | |
243 | if ((ep - cp) < 1 + RRFIXEDSZ) |
244 | return -1; |
245 | |
246 | /* Add the root label. */ |
247 | *cp++ = 0; |
248 | |
249 | NS_PUT16 (T_OPT, cp); /* Record type. */ |
250 | |
251 | /* Lowering the advertised buffer size based on the actual |
252 | answer buffer size is desirable because the server will |
253 | minimize the reply to fit into the UDP packet (and A |
254 | non-minimal response might not fit the buffer). |
255 | |
256 | The RESOLV_EDNS_BUFFER_SIZE limit could still result in TCP |
257 | fallback and a non-minimal response which has to be |
258 | hard-truncated in the stub resolver, but this is price to |
259 | pay for avoiding fragmentation. (This issue does not |
260 | affect the nss_dns functions because they use the stub |
261 | resolver in such a way that it allocates a properly sized |
262 | response buffer.) */ |
263 | { |
264 | uint16_t buffer_size; |
265 | if (anslen < 512) |
266 | buffer_size = 512; |
267 | else if (anslen > RESOLV_EDNS_BUFFER_SIZE) |
268 | buffer_size = RESOLV_EDNS_BUFFER_SIZE; |
269 | else |
270 | buffer_size = anslen; |
271 | NS_PUT16 (buffer_size, cp); |
272 | } |
273 | |
274 | *cp++ = NOERROR; /* Extended RCODE. */ |
275 | *cp++ = 0; /* EDNS version. */ |
276 | |
277 | if (ctx->resp->options & RES_USE_DNSSEC) |
278 | flags |= NS_OPT_DNSSEC_OK; |
279 | |
280 | NS_PUT16 (flags, cp); |
281 | NS_PUT16 (0, cp); /* RDATA length (no options are preent). */ |
282 | hp->arcount = htons (ntohs (hp->arcount) + 1); |
283 | |
284 | return cp - buf; |
285 | } |
286 | |
287 | #if SHLIB_COMPAT (libresolv, GLIBC_2_0, GLIBC_2_2) |
288 | # undef res_mkquery |
289 | weak_alias (__res_mkquery, res_mkquery); |
290 | #endif |
291 | |