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7ab27b76 | 1 | /* Creation of DNS query packets. |
04277e02 | 2 | Copyright (C) 1995-2019 Free Software Foundation, Inc. |
7ab27b76 FW |
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 | ||
28f540f4 | 19 | /* |
28f540f4 RM |
20 | * Copyright (c) 1985, 1993 |
21 | * The Regents of the University of California. All rights reserved. | |
e33b89df | 22 | * |
28f540f4 RM |
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. | |
28f540f4 RM |
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. | |
e33b89df | 34 | * |
28f540f4 RM |
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. | |
b43b13ac UD |
46 | */ |
47 | ||
48 | /* | |
28f540f4 | 49 | * Portions Copyright (c) 1993 by Digital Equipment Corporation. |
e33b89df | 50 | * |
28f540f4 RM |
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. | |
e33b89df | 57 | * |
28f540f4 RM |
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. | |
b43b13ac UD |
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. | |
28f540f4 RM |
83 | */ |
84 | ||
359653aa | 85 | #include <stdint.h> |
df21c858 | 86 | #include <sys/types.h> |
28f540f4 RM |
87 | #include <sys/param.h> |
88 | #include <netinet/in.h> | |
89 | #include <arpa/nameser.h> | |
3d61b63c | 90 | #include <netdb.h> |
e14a2772 | 91 | #include <resolv/resolv-internal.h> |
352f4ff9 | 92 | #include <resolv/resolv_context.h> |
b43b13ac | 93 | #include <string.h> |
f890a59b | 94 | #include <sys/time.h> |
5ca4aaea | 95 | #include <shlib-compat.h> |
359653aa | 96 | #include <random-bits.h> |
e33b89df | 97 | |
28f540f4 | 98 | int |
352f4ff9 FW |
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) | |
28f540f4 | 102 | { |
74084feb FW |
103 | HEADER *hp; |
104 | unsigned char *cp; | |
105 | int n; | |
106 | unsigned char *dnptrs[20], **dpp, **lastdnptr; | |
28f540f4 | 107 | |
74084feb FW |
108 | if (class < 0 || class > 65535 || type < 0 || type > 65535) |
109 | return -1; | |
fc82b0a2 | 110 | |
74084feb FW |
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. */ | |
359653aa | 119 | hp->id = random_bits (); |
74084feb | 120 | hp->opcode = op; |
352f4ff9 | 121 | hp->rd = (ctx->resp->options & RES_RECURSE) != 0; |
74084feb FW |
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]; | |
bce16467 | 129 | |
74084feb FW |
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; | |
28f540f4 | 137 | |
74084feb FW |
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; | |
28f540f4 | 174 | } |
352f4ff9 FW |
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 | } | |
2bbb7d5b | 214 | |
5ca4aaea FW |
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 | { | |
352f4ff9 FW |
221 | return context_mkquery_common |
222 | (__resolv_context_get_preinit (), | |
223 | op, dname, class, type, data, buf, buflen); | |
5ca4aaea FW |
224 | } |
225 | ||
74084feb FW |
226 | /* Create an OPT resource record. Return the length of the final |
227 | packet, or -1 on error. | |
2bbb7d5b | 228 | |
74084feb FW |
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). */ | |
2bbb7d5b | 234 | int |
352f4ff9 FW |
235 | __res_nopt (struct resolv_context *ctx, |
236 | int n0, unsigned char *buf, int buflen, int anslen) | |
2bbb7d5b | 237 | { |
74084feb FW |
238 | uint16_t flags = 0; |
239 | HEADER *hp = (HEADER *) buf; | |
240 | unsigned char *cp = buf + n0; | |
241 | unsigned char *ep = buf + buflen; | |
2bbb7d5b | 242 | |
74084feb FW |
243 | if ((ep - cp) < 1 + RRFIXEDSZ) |
244 | return -1; | |
2bbb7d5b | 245 | |
74084feb FW |
246 | /* Add the root label. */ |
247 | *cp++ = 0; | |
2bbb7d5b | 248 | |
74084feb | 249 | NS_PUT16 (T_OPT, cp); /* Record type. */ |
e14a2772 | 250 | |
74084feb FW |
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). | |
e14a2772 | 255 | |
74084feb FW |
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 | } | |
e14a2772 | 273 | |
74084feb FW |
274 | *cp++ = NOERROR; /* Extended RCODE. */ |
275 | *cp++ = 0; /* EDNS version. */ | |
2d0671cb | 276 | |
352f4ff9 | 277 | if (ctx->resp->options & RES_USE_DNSSEC) |
74084feb | 278 | flags |= NS_OPT_DNSSEC_OK; |
2d0671cb | 279 | |
74084feb FW |
280 | NS_PUT16 (flags, cp); |
281 | NS_PUT16 (0, cp); /* RDATA length (no options are preent). */ | |
282 | hp->arcount = htons (ntohs (hp->arcount) + 1); | |
2bbb7d5b | 283 | |
74084feb | 284 | return cp - buf; |
2bbb7d5b | 285 | } |
5ca4aaea FW |
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 |