1 /*
2 * Copyright (c) 2020 Apple Inc. All rights reserved.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * https://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #include "mdns_message.h"
18
19 #include "mdns_objects.h"
20
21 #include "DNSMessage.h"
22 #include <CoreUtils/CoreUtils.h>
23
24 //======================================================================================================================
25 // MARK: - Message Kind Definition
26
27 struct mdns_message_s {
28 struct mdns_object_s base; // Object base.
29 dispatch_data_t msg_data; // Underlying object for message data.
30 const uint8_t * msg_ptr; // Pointer to first byte of message data.
31 size_t msg_len; // Length of message.
32 bool print_body_only; // True if only the message body should be printed in description.
33 };
34
35 MDNS_OBJECT_SUBKIND_DEFINE(message);
36
37 typedef const struct mdns_message_kind_s * mdns_message_kind_t;
38 struct mdns_message_kind_s {
39 struct mdns_kind_s base;
40 const char * name;
41 };
42
43 #define MDNS_MESSAGE_SUBKIND_DEFINE(NAME) \
44 static void \
45 _mdns_ ## NAME ## _message_finalize(mdns_ ## NAME ## _message_t message); \
46 \
47 static const struct mdns_message_kind_s _mdns_ ## NAME ## _message_kind = { \
48 .base = { \
49 .superkind = &_mdns_message_kind, \
50 .name = "mdns_" # NAME "_message", \
51 .finalize = _mdns_ ## NAME ## _message_finalize \
52 }, \
53 .name = # NAME "_message" \
54 }; \
55 \
56 static mdns_ ## NAME ## _message_t \
57 _mdns_ ## NAME ## _message_alloc(void) \
58 { \
59 mdns_ ## NAME ## _message_t obj; \
60 obj = mdns_ ## NAME ## _message_object_alloc(sizeof(struct mdns_ ## NAME ## _message_s)); \
61 require_return_value(obj, NULL); \
62 \
63 const mdns_object_t object = (mdns_object_t)obj; \
64 object->kind = &_mdns_ ## NAME ## _message_kind.base; \
65 return obj; \
66 } \
67 MDNS_BASE_CHECK(NAME ## _message, message)
68
69 //======================================================================================================================
70 // MARK: - Query Message Kind Definition
71
72 struct mdns_query_message_s {
73 struct mdns_message_s base; // Message object base.
74 uint8_t * qname; // Question's QNAME.
75 uint16_t qtype; // Question's QTYPE.
76 uint16_t qclass; // Question's QCLASS.
77 uint16_t msg_id; // Message ID.
78 bool set_ad_bit; // True if the AD (authentic data) bit is to be set.
79 bool set_cd_bit; // True if the CD (checking disabled) bit is to be set.
80 bool set_do_bit; // True if the DO (DNSSEC OK) bit is to be set in OPT record.
81 bool use_edns0_padding; // True if the query uses EDNS0 padding.
82 bool constructed; // True if the message has been constructed.
83 };
84
85 MDNS_MESSAGE_SUBKIND_DEFINE(query);
86
87 //======================================================================================================================
88 // MARK: - Local Prototypes
89
90 static OSStatus
91 _mdns_message_init(mdns_any_message_t message, dispatch_data_t msg_data, mdns_message_init_options_t options);
92
93 static OSStatus
94 _mdns_message_set_msg_data(mdns_any_message_t message, dispatch_data_t msg_data);
95
96 const uint8_t *
97 _mdns_query_message_get_qname_safe(mdns_query_message_t query_message);
98
99 //======================================================================================================================
100 // MARK: - Messge Public Methods
101
102 mdns_message_t
mdns_message_create_with_dispatch_data(const dispatch_data_t data,const mdns_message_init_options_t options)103 mdns_message_create_with_dispatch_data(const dispatch_data_t data, const mdns_message_init_options_t options)
104 {
105 mdns_message_t message = NULL;
106 mdns_message_t obj = _mdns_message_alloc();
107 require_quiet(obj, exit);
108
109 const OSStatus err = _mdns_message_init(obj, data, options);
110 require_noerr_quiet(err, exit);
111
112 message = obj;
113 obj = NULL;
114
115 exit:
116 mdns_release_null_safe(obj);
117 return message;
118 }
119
120 //======================================================================================================================
121
122 dispatch_data_t
mdns_message_get_dispatch_data(const mdns_message_t me)123 mdns_message_get_dispatch_data(const mdns_message_t me)
124 {
125 return me->msg_data;
126 }
127
128 //======================================================================================================================
129
130 const uint8_t *
mdns_message_get_byte_ptr(const mdns_message_t me)131 mdns_message_get_byte_ptr(const mdns_message_t me)
132 {
133 return me->msg_ptr;
134 }
135
136 //======================================================================================================================
137
138 size_t
mdns_message_get_length(const mdns_message_t me)139 mdns_message_get_length(const mdns_message_t me)
140 {
141 return me->msg_len;
142 }
143
144 //======================================================================================================================
145 // MARK: - Message Private Methods
146
147 static char *
_mdns_message_copy_description(mdns_message_t me,__unused const bool debug,const bool privacy)148 _mdns_message_copy_description(mdns_message_t me, __unused const bool debug, const bool privacy)
149 {
150 char *description = NULL;
151 if (me->msg_ptr) {
152 DNSMessageToStringFlags flags = kDNSMessageToStringFlag_OneLine;
153 if (me->print_body_only) {
154 flags |= kDNSMessageToStringFlag_BodyOnly;
155 }
156 if (privacy) {
157 flags |= kDNSMessageToStringFlag_Privacy;
158 }
159 DNSMessageToString(me->msg_ptr, me->msg_len, flags, &description);
160 }
161 return description;
162 }
163
164 //======================================================================================================================
165
166 static void
_mdns_message_finalize(const mdns_message_t me)167 _mdns_message_finalize(const mdns_message_t me)
168 {
169 me->msg_ptr = NULL;
170 dispatch_forget(&me->msg_data);
171 }
172
173 //======================================================================================================================
174
175 static OSStatus
_mdns_message_init(const mdns_any_message_t any,const dispatch_data_t msg_data,const mdns_message_init_options_t options)176 _mdns_message_init(const mdns_any_message_t any, const dispatch_data_t msg_data,
177 const mdns_message_init_options_t options)
178 {
179 const mdns_message_t me = any.message;
180 if (options & mdns_message_init_option_disable_header_printing) {
181 me->print_body_only = true;
182 }
183 return _mdns_message_set_msg_data(me, msg_data);
184 }
185
186 //======================================================================================================================
187
188 static OSStatus
_mdns_message_set_msg_data(const mdns_any_message_t any,const dispatch_data_t msg_data)189 _mdns_message_set_msg_data(const mdns_any_message_t any, const dispatch_data_t msg_data)
190 {
191 dispatch_data_t msg_data_new;
192 const uint8_t * msg_ptr;
193 size_t msg_len;
194 if (msg_data) {
195 msg_data_new = dispatch_data_create_map(msg_data, (const void **)&msg_ptr, &msg_len);
196 require_return_value(msg_data_new, kNoMemoryErr);
197 } else {
198 msg_data_new = dispatch_data_empty;
199 msg_ptr = NULL;
200 msg_len = 0;
201 }
202 const mdns_message_t me = any.message;
203 dispatch_release_null_safe(me->msg_data);
204 me->msg_data = msg_data_new;
205 me->msg_ptr = msg_ptr;
206 me->msg_len = msg_len;
207 return kNoErr;
208 }
209
210 //======================================================================================================================
211 // MARK: - Query Messge Public Methods
212
213 mdns_query_message_t
mdns_query_message_create(const mdns_message_init_options_t options)214 mdns_query_message_create(const mdns_message_init_options_t options)
215 {
216 mdns_query_message_t message = NULL;
217 mdns_query_message_t obj = _mdns_query_message_alloc();
218 require_quiet(obj, exit);
219
220 const OSStatus err = _mdns_message_init(obj, NULL, options);
221 require_noerr_quiet(err, exit);
222
223 message = obj;
224 obj = NULL;
225
226 exit:
227 mdns_release_null_safe(obj);
228 return message;
229 }
230
231 //======================================================================================================================
232
233 OSStatus
mdns_query_message_set_qname(const mdns_query_message_t me,const uint8_t * const qname)234 mdns_query_message_set_qname(const mdns_query_message_t me, const uint8_t * const qname)
235 {
236 require_return_value(!me->constructed, kNoErr);
237
238 uint8_t *qname_dup = NULL;
239 OSStatus err = DomainNameDup(qname, &qname_dup, NULL);
240 require_noerr_quiet(err, exit);
241
242 FreeNullSafe(me->qname);
243 me->qname = qname_dup;
244 qname_dup = NULL;
245 err = kNoErr;
246
247 exit:
248 return err;
249 }
250
251 //======================================================================================================================
252
253 void
mdns_query_message_set_qtype(const mdns_query_message_t me,const uint16_t qtype)254 mdns_query_message_set_qtype(const mdns_query_message_t me, const uint16_t qtype)
255 {
256 require_return(!me->constructed);
257 me->qtype = qtype;
258 }
259
260 //======================================================================================================================
261
262 void
mdns_query_message_set_qclass(const mdns_query_message_t me,const uint16_t qclass)263 mdns_query_message_set_qclass(const mdns_query_message_t me, const uint16_t qclass)
264 {
265 require_return(!me->constructed);
266 me->qclass = qclass;
267 }
268
269 //======================================================================================================================
270
271 void
mdns_query_message_set_message_id(const mdns_query_message_t me,const uint16_t msg_id)272 mdns_query_message_set_message_id(const mdns_query_message_t me, const uint16_t msg_id)
273 {
274 require_return(!me->constructed);
275 me->msg_id = msg_id;
276 }
277
278 //======================================================================================================================
279
280 void
mdns_query_message_set_ad_bit(const mdns_query_message_t me,const bool set)281 mdns_query_message_set_ad_bit(const mdns_query_message_t me, const bool set)
282 {
283 require_return(!me->constructed);
284 me->set_ad_bit = set;
285 }
286
287 //======================================================================================================================
288
289 void
mdns_query_message_set_cd_bit(const mdns_query_message_t me,const bool set)290 mdns_query_message_set_cd_bit(const mdns_query_message_t me, const bool set)
291 {
292 require_return(!me->constructed);
293 me->set_cd_bit = set;
294 }
295
296 //======================================================================================================================
297
298 void
mdns_query_message_set_do_bit(const mdns_query_message_t me,const bool set)299 mdns_query_message_set_do_bit(const mdns_query_message_t me, const bool set)
300 {
301 require_return(!me->constructed);
302 me->set_do_bit = set;
303 }
304
305 //======================================================================================================================
306
307 void
mdns_query_message_use_edns0_padding(const mdns_query_message_t me,const bool use)308 mdns_query_message_use_edns0_padding(const mdns_query_message_t me, const bool use)
309 {
310 require_return(!me->constructed);
311 me->use_edns0_padding = use;
312 }
313
314 //======================================================================================================================
315
316 #define MDNS_EDNS0_PADDING_OVERHEAD 15 // Size of OPT pseudo-RR with OPTION-CODE and OPTION-LENGTH
317 #define MDNS_EDNS0_PADDING_BLOCK_SIZE 128 // <https://tools.ietf.org/html/rfc8467#section-4.1>
318
319 #define MDNS_QUERY_MESSAGE_BUFFER_SIZE \
320 RoundUp(kDNSQueryMessageMaxLen + MDNS_EDNS0_PADDING_OVERHEAD, MDNS_EDNS0_PADDING_BLOCK_SIZE)
321
322 static OSStatus
323 _mdns_query_message_add_edns0_padding(uint8_t query_buf[static MDNS_QUERY_MESSAGE_BUFFER_SIZE], size_t query_len,
324 bool set_do_bit, size_t *out_len);
325
326 static OSStatus
327 _mdns_query_message_add_edns0_dnssec_ok(uint8_t query_buf[static MDNS_QUERY_MESSAGE_BUFFER_SIZE], size_t query_len,
328 size_t *out_len);
329
330 OSStatus
mdns_query_message_construct(const mdns_query_message_t me)331 mdns_query_message_construct(const mdns_query_message_t me)
332 {
333 uint16_t flags = kDNSHeaderFlag_RecursionDesired;
334 if (me->set_ad_bit) {
335 flags |= kDNSHeaderFlag_AuthenticData;
336 }
337 if (me->set_cd_bit) {
338 flags |= kDNSHeaderFlag_CheckingDisabled;
339 }
340 uint8_t query_buf[MDNS_QUERY_MESSAGE_BUFFER_SIZE];
341 size_t query_len;
342 const uint8_t * const qname = _mdns_query_message_get_qname_safe(me);
343 OSStatus err = DNSMessageWriteQuery(me->msg_id, flags, qname, me->qtype, me->qclass, query_buf, &query_len);
344 require_noerr_quiet(err, exit);
345
346 if (me->use_edns0_padding) {
347 err = _mdns_query_message_add_edns0_padding(query_buf, query_len, me->set_do_bit, &query_len);
348 require_noerr_quiet(err, exit);
349 } else if (me->set_do_bit) {
350 err = _mdns_query_message_add_edns0_dnssec_ok(query_buf, query_len, &query_len);
351 require_noerr_quiet(err, exit);
352 }
353 dispatch_data_t query_data = dispatch_data_create(query_buf, query_len, NULL, DISPATCH_DATA_DESTRUCTOR_DEFAULT);
354 require_action_quiet(query_data, exit, err = kNoMemoryErr);
355
356 err = _mdns_message_set_msg_data(me, query_data);
357 dispatch_forget(&query_data);
358 require_noerr_quiet(err, exit);
359
360 me->constructed = true;
361
362 exit:
363 return err;
364 }
365
366 static OSStatus
_mdns_query_message_add_edns0_padding(uint8_t query_buf[static MDNS_QUERY_MESSAGE_BUFFER_SIZE],const size_t query_len,const bool set_do_bit,size_t * const out_len)367 _mdns_query_message_add_edns0_padding(uint8_t query_buf[static MDNS_QUERY_MESSAGE_BUFFER_SIZE], const size_t query_len,
368 const bool set_do_bit, size_t * const out_len)
369 {
370 const size_t new_len = RoundUp(query_len + MDNS_EDNS0_PADDING_OVERHEAD, MDNS_EDNS0_PADDING_BLOCK_SIZE);
371 require_return_value(new_len <= MDNS_QUERY_MESSAGE_BUFFER_SIZE, kSizeErr);
372
373 uint8_t * const end = &query_buf[query_len];
374 const uint8_t * const new_end = &query_buf[new_len];
375 memset(end, 0, (size_t)(new_end - end));
376
377 check_compile_time_code(MDNS_EDNS0_PADDING_OVERHEAD == sizeof(dns_fixed_fields_opt1));
378
379 dns_fixed_fields_opt1 * const pad_opt = (dns_fixed_fields_opt1 *)end;
380 const uint8_t * const pad_start = (const uint8_t *)&pad_opt[1];
381 dns_fixed_fields_opt1_set_type(pad_opt, kDNSRecordType_OPT);
382 dns_fixed_fields_opt1_set_udp_payload_size(pad_opt, 512);
383 dns_fixed_fields_opt1_set_rdlen(pad_opt, (uint16_t)(new_end - pad_opt->option_code));
384 dns_fixed_fields_opt1_set_option_code(pad_opt, kDNSEDNS0OptionCode_Padding);
385 dns_fixed_fields_opt1_set_option_length(pad_opt, (uint16_t)(new_end - pad_start));
386 if (set_do_bit) {
387 dns_fixed_fields_opt1_set_extended_flags(pad_opt, kDNSExtendedFlag_DNSSECOK);
388 }
389 DNSHeaderSetAdditionalCount((DNSHeader *)&query_buf[0], 1);
390 if (out_len) {
391 *out_len = new_len;
392 }
393 return kNoErr;
394 }
395
396 static OSStatus
_mdns_query_message_add_edns0_dnssec_ok(uint8_t query_buf[static MDNS_QUERY_MESSAGE_BUFFER_SIZE],const size_t query_len,size_t * const out_len)397 _mdns_query_message_add_edns0_dnssec_ok(uint8_t query_buf[static MDNS_QUERY_MESSAGE_BUFFER_SIZE],
398 const size_t query_len, size_t * const out_len)
399 {
400 dns_fixed_fields_opt *opt;
401 const size_t new_len = query_len + sizeof(*opt);
402 require_return_value(new_len <= MDNS_QUERY_MESSAGE_BUFFER_SIZE, kSizeErr);
403
404 opt = (dns_fixed_fields_opt *)&query_buf[query_len];
405 memset(opt, 0, sizeof(*opt));
406 dns_fixed_fields_opt_set_type(opt, kDNSRecordType_OPT);
407 dns_fixed_fields_opt_set_udp_payload_size(opt, 512);
408 dns_fixed_fields_opt_set_extended_flags(opt, kDNSExtendedFlag_DNSSECOK);
409
410 DNSHeaderSetAdditionalCount((DNSHeader *)&query_buf[0], 1);
411 if (out_len) {
412 *out_len = new_len;
413 }
414 return kNoErr;
415 }
416
417 //======================================================================================================================
418
419 const uint8_t *
mdns_query_message_get_qname(const mdns_query_message_t me)420 mdns_query_message_get_qname(const mdns_query_message_t me)
421 {
422 return _mdns_query_message_get_qname_safe(me);
423 }
424
425 //======================================================================================================================
426
427 uint16_t
mdns_query_message_get_qtype(const mdns_query_message_t me)428 mdns_query_message_get_qtype(const mdns_query_message_t me)
429 {
430 return me->qtype;
431 }
432
433 //======================================================================================================================
434
435 uint16_t
mdns_query_message_get_qclass(const mdns_query_message_t me)436 mdns_query_message_get_qclass(const mdns_query_message_t me)
437 {
438 return me->qclass;
439 }
440
441 //======================================================================================================================
442
443 uint16_t
mdns_query_message_get_message_id(const mdns_query_message_t me)444 mdns_query_message_get_message_id(const mdns_query_message_t me)
445 {
446 return me->msg_id;
447 }
448
449 //======================================================================================================================
450
451 bool
mdns_query_message_do_bit_is_set(const mdns_query_message_t me)452 mdns_query_message_do_bit_is_set(const mdns_query_message_t me)
453 {
454 return me->set_do_bit;
455 }
456
457 //======================================================================================================================
458 // MARK: - Query Message Private Methods
459
460 static void
_mdns_query_message_finalize(const mdns_query_message_t me)461 _mdns_query_message_finalize(const mdns_query_message_t me)
462 {
463 ForgetMem(&me->qname);
464 }
465
466 //======================================================================================================================
467
468 const uint8_t *
_mdns_query_message_get_qname_safe(const mdns_query_message_t me)469 _mdns_query_message_get_qname_safe(const mdns_query_message_t me)
470 {
471 return (me->qname ? me->qname : (const uint8_t *)"");
472 }
473