1 /*
2 * Copyright (c) 2016 Intel Corporation
3 *
4 * SPDX-License-Identifier: Apache-2.0
5 */
6
7 #ifndef _DNS_PACK_H_
8 #define _DNS_PACK_H_
9
10 #include <net/net_ip.h>
11 #include <net/buf.h>
12
13 #include <zephyr/types.h>
14 #include <stddef.h>
15 #include <errno.h>
16
17 /* See RFC 1035, 4.1.1 Header section format
18 * DNS Message Header is always 12 bytes
19 */
20 #define DNS_MSG_HEADER_SIZE 12
21
22 /* This is the label's length octet, see 4.1.2. Question section format */
23 #define DNS_LABEL_LEN_SIZE 1
24 #define DNS_POINTER_SIZE 2
25 #define DNS_LABEL_MIN_SIZE 1
26 #define DNS_LABEL_MAX_SIZE 63
27 #define DNS_NAME_MAX_SIZE 255
28 #define DNS_ANSWER_MIN_SIZE 12
29 #define DNS_COMMON_UINT_SIZE 2
30
31 #define DNS_HEADER_ID_LEN 2
32 #define DNS_HEADER_FLAGS_LEN 2
33 #define DNS_QTYPE_LEN 2
34 #define DNS_QCLASS_LEN 2
35 #define DNS_QDCOUNT_LEN 2
36 #define DNS_ANCOUNT_LEN 2
37 #define DNS_NSCOUNT_LEN 2
38 #define DNS_ARCOUNT_LEN 2
39 #define DNS_TTL_LEN 4
40 #define DNS_RDLENGTH_LEN 2
41
42 #define NS_CMPRSFLGS 0xc0 /* DNS name compression */
43
44 /* RFC 1035 '4.1.1. Header section format' defines the following flags:
45 * QR, Opcode, AA, TC, RD, RA, Z and RCODE.
46 * This implementation only uses RD (Recursion Desired).
47 */
48 #define DNS_RECURSION 1
49
50 /* These two defines represent the 3rd and 4th bytes of the DNS msg header.
51 * See RFC 1035, 4.1.1. Header section format.
52 */
53 #define DNS_FLAGS1 DNS_RECURSION /* QR, Opcode, AA, and TC = 0 */
54 #define DNS_FLAGS2 0 /* RA, Z and RCODE = 0 */
55
56 /**
57 * DNS message structure for DNS responses
58 *
59 * Structure that points to the buffer containing the DNS message. It also
60 * contains some decodified message's properties that can not be recovered
61 * easily:
62 * - cname_offset
63 * - query_offset
64 * - answer_offset:
65 * + response_type: It indicates the response's content type. It could be
66 * an IP address, a CNAME with IP (two answers), a CNAME with no IP
67 * address. See enum dns_response_type for more details.
68 * + response_position: this is an offset. It holds the starting byte of
69 * the field containing the desired info. For example an IPv4 address.
70 * + response_length: this is an offset. It holds the response's length.
71 */
72 struct dns_msg_t {
73 uint8_t *msg;
74
75 int response_type;
76 uint16_t response_position;
77 uint16_t response_length;
78
79 uint16_t query_offset;
80 uint16_t answer_offset;
81 uint16_t msg_size;
82 };
83
84 #define DNS_MSG_INIT(b, s) {.msg = b, .msg_size = s, \
85 .response_type = -EINVAL}
86
87
88 enum dns_rr_type {
89 DNS_RR_TYPE_INVALID = 0,
90 DNS_RR_TYPE_A = 1, /* IPv4 */
91 DNS_RR_TYPE_CNAME = 5, /* CNAME */
92 DNS_RR_TYPE_PTR = 12, /* PTR */
93 DNS_RR_TYPE_TXT = 16, /* TXT */
94 DNS_RR_TYPE_AAAA = 28, /* IPv6 */
95 DNS_RR_TYPE_SRV = 33, /* SRV */
96 };
97
98 enum dns_response_type {
99 DNS_RESPONSE_INVALID = -EINVAL,
100 DNS_RESPONSE_IP,
101 DNS_RESPONSE_CNAME_WITH_IP,
102 DNS_RESPONSE_CNAME_NO_IP
103 };
104
105 enum dns_class {
106 DNS_CLASS_INVALID = 0,
107 DNS_CLASS_IN,
108 DNS_CLASS_FLUSH = BIT(15)
109 };
110
111 enum dns_msg_type {
112 DNS_QUERY = 0,
113 DNS_RESPONSE
114 };
115
116 enum dns_header_rcode {
117 DNS_HEADER_NOERROR = 0,
118 DNS_HEADER_FORMATERROR,
119 DNS_HEADER_SERVERFAILURE,
120 DNS_HEADER_NAMEERROR,
121 DNS_HEADER_NOTIMPLEMENTED,
122 DNS_HEADER_REFUSED
123 };
124
125 struct dns_header {
126 /** Transaction ID */
127 uint16_t id;
128 /**
129 * | Name | Bit Position | Width | Description |
130 * |------|--------------|-------|-------------|
131 * | RCODE | 0 | 4 | Response / Error code |
132 * | CD | 4 | 1 | |
133 * | AD | 5 | 1 | Authenticated Data. 0 := Unacceptable, 1 := Acceptable |
134 * | Z | 6 | 1 | Reserved (WZ/RAZ) |
135 * | RA | 7 | 1 | Recursion Available. 0 := Unavailable, 1 := Available |
136 * | RD | 8 | 1 | Recursion Desired. 0 := No Recursion, 1 := Recursion |
137 * | TC | 9 | 1 | 0 := Not Truncated, 1 := Truncated |
138 * | AA | 10 | 1 | Answer Authenticated / Answer Authoritative. 0 := Not Authenticated, 1 := Authenticated|
139 * | Opcode | 11 | 4 | See @ref dns_opcode |
140 * | QR | 15 | 1 | 0 := Query, 1 := Response |
141 */
142 uint16_t flags;
143 /** Query count */
144 uint16_t qdcount;
145 /** Answer count */
146 uint16_t ancount;
147 /** Authority count */
148 uint16_t nscount;
149 /** Additional information count */
150 uint16_t arcount;
151 /** Flexible array member for records */
152 uint8_t data[];
153 } __packed;
154
155 struct dns_query {
156 uint16_t type;
157 uint16_t class_;
158 } __packed;
159
160 struct dns_rr {
161 uint16_t type;
162 uint16_t class_;
163 uint32_t ttl;
164 uint16_t rdlength;
165 uint8_t rdata[];
166 } __packed;
167
168 struct dns_srv_rdata {
169 uint16_t priority;
170 uint16_t weight;
171 uint16_t port;
172 } __packed;
173
174 struct dns_a_rdata {
175 uint32_t address;
176 } __packed;
177
178 struct dns_aaaa_rdata {
179 uint8_t address[16];
180 } __packed;
181
182 /** It returns the ID field in the DNS msg header */
dns_header_id(uint8_t * header)183 static inline int dns_header_id(uint8_t *header)
184 {
185 return htons(UNALIGNED_GET((uint16_t *)(header)));
186 }
187
188 /* inline unpack routines are used to unpack data from network
189 * order to cpu. Similar routines without the unpack prefix are
190 * used for cpu to network order.
191 */
dns_unpack_header_id(uint8_t * header)192 static inline int dns_unpack_header_id(uint8_t *header)
193 {
194 return ntohs(UNALIGNED_GET((uint16_t *)(header)));
195 }
196
197 /** It returns the QR field in the DNS msg header */
dns_header_qr(uint8_t * header)198 static inline int dns_header_qr(uint8_t *header)
199 {
200 return ((*(header + 2)) & 0x80) ? 1 : 0;
201 }
202
203 /** It returns the OPCODE field in the DNS msg header */
dns_header_opcode(uint8_t * header)204 static inline int dns_header_opcode(uint8_t *header)
205 {
206 return ((*(header + 2)) & 0x70) >> 1;
207 }
208
209 /** It returns the AA field in the DNS msg header */
dns_header_aa(uint8_t * header)210 static inline int dns_header_aa(uint8_t *header)
211 {
212 return ((*(header + 2)) & 0x04) ? 1 : 0;
213 }
214
215 /** It returns the TC field in the DNS msg header */
dns_header_tc(uint8_t * header)216 static inline int dns_header_tc(uint8_t *header)
217 {
218 return ((*(header + 2)) & 0x02) ? 1 : 0;
219 }
220
221 /** It returns the RD field in the DNS msg header */
dns_header_rd(uint8_t * header)222 static inline int dns_header_rd(uint8_t *header)
223 {
224 return ((*(header + 2)) & 0x01) ? 1 : 0;
225 }
226
227 /** It returns the RA field in the DNS msg header */
dns_header_ra(uint8_t * header)228 static inline int dns_header_ra(uint8_t *header)
229 {
230 return ((*(header + 3)) & 0x80) >> 7;
231 }
232
233 /** It returns the Z field in the DNS msg header */
dns_header_z(uint8_t * header)234 static inline int dns_header_z(uint8_t *header)
235 {
236 return ((*(header + 3)) & 0x70) >> 4;
237 }
238
239 /** It returns the RCODE field in the DNS msg header */
dns_header_rcode(uint8_t * header)240 static inline int dns_header_rcode(uint8_t *header)
241 {
242 return ((*(header + 3)) & 0x0F);
243 }
244
245 /** It returns the QDCOUNT field in the DNS msg header */
dns_header_qdcount(uint8_t * header)246 static inline int dns_header_qdcount(uint8_t *header)
247 {
248 return htons(UNALIGNED_GET((uint16_t *)(header + 4)));
249 }
250
dns_unpack_header_qdcount(uint8_t * header)251 static inline int dns_unpack_header_qdcount(uint8_t *header)
252 {
253 return ntohs(UNALIGNED_GET((uint16_t *)(header + 4)));
254 }
255
256 /** It returns the ANCOUNT field in the DNS msg header */
dns_header_ancount(uint8_t * header)257 static inline int dns_header_ancount(uint8_t *header)
258 {
259 return htons(UNALIGNED_GET((uint16_t *)(header + 6)));
260 }
261
dns_unpack_header_ancount(uint8_t * header)262 static inline int dns_unpack_header_ancount(uint8_t *header)
263 {
264 return ntohs(UNALIGNED_GET((uint16_t *)(header + 6)));
265 }
266
267 /** It returns the NSCOUNT field in the DNS msg header */
dns_header_nscount(uint8_t * header)268 static inline int dns_header_nscount(uint8_t *header)
269 {
270 return htons(UNALIGNED_GET((uint16_t *)(header + 8)));
271 }
272
273 /** It returns the ARCOUNT field in the DNS msg header */
dns_header_arcount(uint8_t * header)274 static inline int dns_header_arcount(uint8_t *header)
275 {
276 return htons(UNALIGNED_GET((uint16_t *)(header + 10)));
277 }
278
dns_query_qtype(uint8_t * question)279 static inline int dns_query_qtype(uint8_t *question)
280 {
281 return htons(UNALIGNED_GET((uint16_t *)(question + 0)));
282 }
283
dns_unpack_query_qtype(const uint8_t * question)284 static inline int dns_unpack_query_qtype(const uint8_t *question)
285 {
286 return ntohs(UNALIGNED_GET((uint16_t *)(question + 0)));
287 }
288
dns_query_qclass(uint8_t * question)289 static inline int dns_query_qclass(uint8_t *question)
290 {
291 return htons(UNALIGNED_GET((uint16_t *)(question + 2)));
292 }
293
dns_unpack_query_qclass(const uint8_t * question)294 static inline int dns_unpack_query_qclass(const uint8_t *question)
295 {
296 return ntohs(UNALIGNED_GET((uint16_t *)(question + 2)));
297 }
298
dns_answer_type(uint16_t dname_size,uint8_t * answer)299 static inline int dns_answer_type(uint16_t dname_size, uint8_t *answer)
300 {
301 /* 4.1.3. Resource record format */
302 return ntohs(UNALIGNED_GET((uint16_t *)(answer + dname_size + 0)));
303 }
304
dns_answer_class(uint16_t dname_size,uint8_t * answer)305 static inline int dns_answer_class(uint16_t dname_size, uint8_t *answer)
306 {
307 /* 4.1.3. Resource record format */
308 return ntohs(UNALIGNED_GET((uint16_t *)(answer + dname_size + 2)));
309 }
310
dns_answer_ttl(uint16_t dname_size,uint8_t * answer)311 static inline int dns_answer_ttl(uint16_t dname_size, uint8_t *answer)
312 {
313 return ntohl(UNALIGNED_GET((uint32_t *)(answer + dname_size + 4)));
314 }
315
dns_answer_rdlength(uint16_t dname_size,uint8_t * answer)316 static inline int dns_answer_rdlength(uint16_t dname_size,
317 uint8_t *answer)
318 {
319 return ntohs(UNALIGNED_GET((uint16_t *)(answer + dname_size + 8)));
320 }
321
322 /**
323 * @brief Packs a QNAME
324 *
325 * @param len Bytes used by this function
326 * @param buf Buffer
327 * @param sizeof Buffer's size
328 * @param domain_name Something like www.example.com
329 * @retval 0 on success
330 * @retval -ENOMEM if there is no enough space to store the resultant QNAME
331 * @retval -EINVAL if an invalid parameter was passed as an argument
332 */
333 int dns_msg_pack_qname(uint16_t *len, uint8_t *buf, uint16_t size,
334 const char *domain_name);
335
336 /**
337 * @brief Unpacks an answer message
338 *
339 * @param dns_msg Structure
340 * @param dname_ptr An index to the previous CNAME. For example for the
341 * first answer, ptr must be 0x0c, the DNAME at the question.
342 * @param ttl TTL answer parameter.
343 * @param type Answer type parameter.
344 * @retval 0 on success
345 * @retval -ENOMEM on error
346 */
347 int dns_unpack_answer(struct dns_msg_t *dns_msg, int dname_ptr, uint32_t *ttl,
348 enum dns_rr_type *type);
349
350 /**
351 * @brief Unpacks the header's response.
352 *
353 * @param msg Structure containing the response.
354 * @param src_id Transaction id, it must match the id used in the query
355 * datagram sent to the DNS server.
356 * @retval 0 on success
357 * @retval -ENOMEM if the buffer in msg has no enough space to store the header.
358 * The header is always 12 bytes length.
359 * @retval -EINVAL if the src_id does not match the header's id, or if the
360 * header's QR value is not DNS_RESPONSE or if the header's OPCODE
361 * value is not DNS_QUERY, or if the header's Z value is not 0 or if
362 * the question counter is not 1 or the answer counter is less than 1.
363 * @retval RFC 1035 RCODEs (> 0) 1 Format error, 2 Server failure, 3 Name Error,
364 * 4 Not Implemented and 5 Refused.
365 */
366 int dns_unpack_response_header(struct dns_msg_t *msg, int src_id);
367
368 /**
369 * @brief Packs the query message
370 *
371 * @param buf Buffer that will contain the resultant query
372 * @param len Number of bytes used to encode the query
373 * @param size Buffer size
374 * @param qname Domain name represented as a sequence of labels.
375 * See RFC 1035, 4.1.2. Question section format.
376 * @param qname_len Number of octets in qname.
377 * @param id Transaction Identifier
378 * @param qtype Query type: AA, AAAA. See enum dns_rr_type
379 * @retval 0 on success
380 * @retval On error, a negative value is returned.
381 * See: dns_msg_pack_query_header and dns_msg_pack_qname.
382 */
383 int dns_msg_pack_query(uint8_t *buf, uint16_t *len, uint16_t size,
384 uint8_t *qname, uint16_t qname_len, uint16_t id,
385 enum dns_rr_type qtype);
386
387 /**
388 * @brief Unpacks the response's query.
389 *
390 * @details RFC 1035 states that the response's query comes after the first
391 * 12 bytes i.e., after the message's header. This function computes
392 * the answer_offset field.
393 *
394 * @param dns_msg Structure containing the message.
395 * @retval 0 on success
396 * @retval -ENOMEM if the null label is not found after traversing the buffer
397 * or if QCLASS and QTYPE are not found.
398 * @retval -EINVAL if QTYPE is not "A" (IPv4) or "AAAA" (IPv6) or if QCLASS
399 * is not "IN".
400 */
401 int dns_unpack_response_query(struct dns_msg_t *dns_msg);
402
403 /**
404 * @brief Copies the qname from dns_msg to buf
405 *
406 * @details This routine implements the algorithm described in RFC 1035, 4.1.4.
407 * Message compression to copy the qname (perhaps containing pointers
408 * with offset) to the linear buffer buf. Pointers are removed and
409 * only the "true" labels are copied.
410 *
411 * @param buf Output buffer
412 * @param len Output buffer's length
413 * @param size Output buffer's size
414 * @param dns_msg Structure containing the message
415 * @param pos QNAME's position in dns_msg->msg
416 * @retval 0 on success
417 * @retval -EINVAL if an invalid parameter was passed as an argument
418 * @retval -ENOMEM if the label's size is corrupted
419 */
420 int dns_copy_qname(uint8_t *buf, uint16_t *len, uint16_t size,
421 struct dns_msg_t *dns_msg, uint16_t pos);
422
423 /**
424 * @brief Unpacks the mDNS query. This is special version for multicast DNS
425 * as it skips checks to various fields as described in RFC 6762
426 * chapter 18.
427 *
428 * @param msg Structure containing the response.
429 * @param src_id Transaction id, this is returned to the caller.
430 * @retval 0 on success, <0 if error
431 * @retval -ENOMEM if the buffer in msg has no enough space to store the header.
432 * The header is always 12 bytes length.
433 * @retval -EINVAL if the src_id does not match the header's id, or if the
434 * header's QR value is not DNS_RESPONSE or if the header's OPCODE
435 * value is not DNS_QUERY, or if the header's Z value is not 0 or if
436 * the question counter is not 1 or the answer counter is less than 1.
437 * @retval RFC 1035 RCODEs (> 0) 1 Format error, 2 Server failure, 3 Name Error,
438 * 4 Not Implemented and 5 Refused.
439 */
440 int mdns_unpack_query_header(struct dns_msg_t *msg, uint16_t *src_id);
441
llmnr_unpack_query_header(struct dns_msg_t * msg,uint16_t * src_id)442 static inline int llmnr_unpack_query_header(struct dns_msg_t *msg,
443 uint16_t *src_id)
444 {
445 return mdns_unpack_query_header(msg, src_id);
446 }
447
448 /**
449 * @brief Unpacks the query.
450 *
451 * @param dns_msg Structure containing the message.
452 * @param buf Result buf
453 * @param qtype Query type is returned to caller
454 * @param qclass Query class is returned to caller
455 * @retval 0 on success
456 * @retval -ENOMEM if the null label is not found after traversing the buffer
457 * or if QCLASS and QTYPE are not found.
458 * @retval -EINVAL if QTYPE is not "A" (IPv4) or "AAAA" (IPv6) or if QCLASS
459 * is not "IN".
460 */
461 int dns_unpack_query(struct dns_msg_t *dns_msg, struct net_buf *buf,
462 enum dns_rr_type *qtype,
463 enum dns_class *qclass);
464
465 #endif
466
