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22 * @file include/gnunet_dnsparser_lib.h
23 * @brief API for helper library to parse DNS packets.
24 * @author Philipp Toelke
25 * @author Christian Grothoff
27 #ifndef GNUNET_DNSPARSER_LIB_H
28 #define GNUNET_DNSPARSER_LIB_H
30 #include "gnunet_common.h"
33 * Maximum length of a label in DNS.
35 #define GNUNET_DNSPARSER_MAX_LABEL_LENGTH 63
38 * Maximum length of a name in DNS.
40 #define GNUNET_DNSPARSER_MAX_NAME_LENGTH 253
44 * A few common DNS types.
46 #define GNUNET_DNSPARSER_TYPE_A 1
47 #define GNUNET_DNSPARSER_TYPE_NS 2
48 #define GNUNET_DNSPARSER_TYPE_CNAME 5
49 #define GNUNET_DNSPARSER_TYPE_SOA 6
50 #define GNUNET_DNSPARSER_TYPE_PTR 12
51 #define GNUNET_DNSPARSER_TYPE_MX 15
52 #define GNUNET_DNSPARSER_TYPE_TXT 16
53 #define GNUNET_DNSPARSER_TYPE_AAAA 28
54 #define GNUNET_DNSPARSER_TYPE_SRV 33
55 #define GNUNET_DNSPARSER_TYPE_TLSA 52
58 * A few common DNS classes (ok, only one is common, but I list a
59 * couple more to make it clear what we're talking about here).
61 #define GNUNET_DNSPARSER_CLASS_INTERNET 1
62 #define GNUNET_DNSPARSER_CLASS_CHAOS 3
63 #define GNUNET_DNSPARSER_CLASS_HESIOD 4
65 #define GNUNET_DNSPARSER_OPCODE_QUERY 0
66 #define GNUNET_DNSPARSER_OPCODE_INVERSE_QUERY 1
67 #define GNUNET_DNSPARSER_OPCODE_STATUS 2
72 #define GNUNET_DNSPARSER_RETURN_CODE_NO_ERROR 0
73 #define GNUNET_DNSPARSER_RETURN_CODE_FORMAT_ERROR 1
74 #define GNUNET_DNSPARSER_RETURN_CODE_SERVER_FAILURE 2
75 #define GNUNET_DNSPARSER_RETURN_CODE_NAME_ERROR 3
76 #define GNUNET_DNSPARSER_RETURN_CODE_NOT_IMPLEMENTED 4
77 #define GNUNET_DNSPARSER_RETURN_CODE_REFUSED 5
82 #define GNUNET_DNSPARSER_RETURN_CODE_YXDOMAIN 6
83 #define GNUNET_DNSPARSER_RETURN_CODE_YXRRSET 7
84 #define GNUNET_DNSPARSER_RETURN_CODE_NXRRSET 8
85 #define GNUNET_DNSPARSER_RETURN_CODE_NOT_AUTH 9
86 #define GNUNET_DNSPARSER_RETURN_CODE_NOT_ZONE 10
89 * DNS flags (largely RFC 1035 / RFC 2136).
91 struct GNUNET_DNSPARSER_Flags
93 #if __BYTE_ORDER == __LITTLE_ENDIAN
95 * Set to 1 if recursion is desired (client -> server)
97 unsigned int recursion_desired : 1 GNUNET_PACKED;
100 * Set to 1 if message is truncated
102 unsigned int message_truncated : 1 GNUNET_PACKED;
105 * Set to 1 if this is an authoritative answer
107 unsigned int authoritative_answer : 1 GNUNET_PACKED;
110 * See GNUNET_DNSPARSER_OPCODE_ defines.
112 unsigned int opcode : 4 GNUNET_PACKED;
115 * query:0, response:1
117 unsigned int query_or_response : 1 GNUNET_PACKED;
120 * See GNUNET_DNSPARSER_RETURN_CODE_ defines.
122 unsigned int return_code : 4 GNUNET_PACKED;
127 unsigned int checking_disabled : 1 GNUNET_PACKED;
130 * Response has been cryptographically verified, RFC 4035.
132 unsigned int authenticated_data : 1 GNUNET_PACKED;
137 unsigned int zero : 1 GNUNET_PACKED;
140 * Set to 1 if recursion is available (server -> client)
142 unsigned int recursion_available : 1 GNUNET_PACKED;
143 #elif __BYTE_ORDER == __BIG_ENDIAN
146 * query:0, response:1
148 unsigned int query_or_response : 1 GNUNET_PACKED;
151 * See GNUNET_DNSPARSER_OPCODE_ defines.
153 unsigned int opcode : 4 GNUNET_PACKED;
156 * Set to 1 if this is an authoritative answer
158 unsigned int authoritative_answer : 1 GNUNET_PACKED;
161 * Set to 1 if message is truncated
163 unsigned int message_truncated : 1 GNUNET_PACKED;
166 * Set to 1 if recursion is desired (client -> server)
168 unsigned int recursion_desired : 1 GNUNET_PACKED;
172 * Set to 1 if recursion is available (server -> client)
174 unsigned int recursion_available : 1 GNUNET_PACKED;
179 unsigned int zero : 1 GNUNET_PACKED;
182 * Response has been cryptographically verified, RFC 4035.
184 unsigned int authenticated_data : 1 GNUNET_PACKED;
189 unsigned int checking_disabled : 1 GNUNET_PACKED;
192 * See GNUNET_DNSPARSER_RETURN_CODE_ defines.
194 unsigned int return_code : 4 GNUNET_PACKED;
196 #error byteorder undefined
199 } GNUNET_GCC_STRUCT_LAYOUT;
205 struct GNUNET_DNSPARSER_Query
209 * Name of the record that the query is for (0-terminated).
210 * In UTF-8 format. The library will convert from and to DNS-IDNA
211 * as necessary. Use 'GNUNET_DNSPARSER_check_label' to test if an
212 * individual label is well-formed. If a given name is not well-formed,
213 * creating the DNS packet will fail.
218 * See GNUNET_DNSPARSER_TYPE_*.
223 * See GNUNET_DNSPARSER_CLASS_*.
231 * Information from MX records (RFC 1035).
233 struct GNUNET_DNSPARSER_MxRecord
237 * Preference for this entry (lower value is higher preference).
242 * Name of the mail server.
243 * In UTF-8 format. The library will convert from and to DNS-IDNA
244 * as necessary. Use 'GNUNET_DNSPARSER_check_label' to test if an
245 * individual label is well-formed. If a given name is not well-formed,
246 * creating the DNS packet will fail.
254 * Information from SRV records (RFC 2782). The 'service', 'proto'
255 * and 'domain_name' fields together give the DNS-name which for SRV
256 * records is of the form "_$SERVICE._$PROTO.$DOMAIN_NAME". The DNS
257 * parser provides the full name in 'struct DNSPARSER_Record' and the
258 * individual components in the respective fields of this struct.
259 * When serializing, you CAN set the 'name' field of 'struct
260 * GNUNET_DNSPARSER_Record' to NULL, in which case the DNSPARSER code
261 * will populate 'name' from the 'service', 'proto' and 'domain_name'
262 * fields in this struct.
264 struct GNUNET_DNSPARSER_SrvRecord
268 * Service name without the underscore (!). Note that RFC 6335 clarifies the
269 * set of legal characters for service names.
270 * In UTF-8 format. The library will convert from and to DNS-IDNA
271 * as necessary. Use 'GNUNET_DNSPARSER_check_label' to test if an
272 * individual label is well-formed. If a given name is not well-formed,
273 * creating the DNS packet will fail.
278 * Transport protocol (typcially "tcp" or "udp", but others might be allowed).
279 * Without the underscore (!).
284 * Domain name for which the record is valid
285 * In UTF-8 format. The library will convert from and to DNS-IDNA
286 * as necessary. Use 'GNUNET_DNSPARSER_check_label' to test if an
287 * individual label is well-formed. If a given name is not well-formed,
288 * creating the DNS packet will fail.
293 * Hostname offering the service.
294 * In UTF-8 format. The library will convert from and to DNS-IDNA
295 * as necessary. Use 'GNUNET_DNSPARSER_check_label' to test if an
296 * individual label is well-formed. If a given name is not well-formed,
297 * creating the DNS packet will fail.
302 * Preference for this entry (lower value is higher preference). Clients
303 * will contact hosts from the lowest-priority group first and fall back
304 * to higher priorities if the low-priority entries are unavailable.
309 * Relative weight for records with the same priority. Clients will use
310 * the hosts of the same (lowest) priority with a probability proportional
311 * to the weight given.
316 * TCP or UDP port of the service.
324 * Information from SOA records (RFC 1035).
326 struct GNUNET_DNSPARSER_SoaRecord
330 *The domainname of the name server that was the
331 * original or primary source of data for this zone.
332 * In UTF-8 format. The library will convert from and to DNS-IDNA
333 * as necessary. Use 'GNUNET_DNSPARSER_check_label' to test if an
334 * individual label is well-formed. If a given name is not well-formed,
335 * creating the DNS packet will fail.
340 * A domainname which specifies the mailbox of the
341 * person responsible for this zone.
342 * In UTF-8 format. The library will convert from and to DNS-IDNA
343 * as necessary. Use 'GNUNET_DNSPARSER_check_label' to test if an
344 * individual label is well-formed. If a given name is not well-formed,
345 * creating the DNS packet will fail.
350 * The version number of the original copy of the zone.
355 * Time interval before the zone should be refreshed.
360 * Time interval that should elapse before a failed refresh should
366 * Time value that specifies the upper limit on the time interval
367 * that can elapse before the zone is no longer authoritative.
372 * The bit minimum TTL field that should be exported with any RR
375 uint32_t minimum_ttl;
381 * Binary record information (unparsed).
383 struct GNUNET_DNSPARSER_RawRecord
387 * Binary record data.
392 * Number of bytes in data.
399 * A DNS response record.
401 struct GNUNET_DNSPARSER_Record
405 * Name of the record that the query is for (0-terminated).
406 * In UTF-8 format. The library will convert from and to DNS-IDNA
407 * as necessary. Use 'GNUNET_DNSPARSER_check_label' to test if an
408 * individual label is well-formed. If a given name is not well-formed,
409 * creating the DNS packet will fail.
414 * Payload of the record (which one of these is valid depends on the 'type').
420 * For NS, CNAME and PTR records, this is the uncompressed 0-terminated hostname.
421 * In UTF-8 format. The library will convert from and to DNS-IDNA
422 * as necessary. Use 'GNUNET_DNSPARSER_check_label' to test if an
423 * individual label is well-formed. If a given name is not well-formed,
424 * creating the DNS packet will fail.
429 * SOA data for SOA records.
431 struct GNUNET_DNSPARSER_SoaRecord *soa;
434 * MX data for MX records.
436 struct GNUNET_DNSPARSER_MxRecord *mx;
439 * SRV data for SRV records.
441 struct GNUNET_DNSPARSER_SrvRecord *srv;
444 * Raw data for all other types.
446 struct GNUNET_DNSPARSER_RawRecord raw;
452 * When does the record expire?
454 struct GNUNET_TIME_Absolute expiration_time;
457 * See GNUNET_DNSPARSER_TYPE_*.
462 * See GNUNET_DNSPARSER_CLASS_*.
470 * Easy-to-process, parsed version of a DNS packet.
472 struct GNUNET_DNSPARSER_Packet
475 * Array of all queries in the packet, must contain "num_queries" entries.
477 struct GNUNET_DNSPARSER_Query *queries;
480 * Array of all answers in the packet, must contain "num_answers" entries.
482 struct GNUNET_DNSPARSER_Record *answers;
485 * Array of all authority records in the packet, must contain "num_authority_records" entries.
487 struct GNUNET_DNSPARSER_Record *authority_records;
490 * Array of all additional answers in the packet, must contain "num_additional_records" entries.
492 struct GNUNET_DNSPARSER_Record *additional_records;
495 * Number of queries in the packet.
497 unsigned int num_queries;
500 * Number of answers in the packet, should be 0 for queries.
502 unsigned int num_answers;
505 * Number of authoritative answers in the packet, should be 0 for queries.
507 unsigned int num_authority_records;
510 * Number of additional records in the packet, should be 0 for queries.
512 unsigned int num_additional_records;
515 * Bitfield of DNS flags.
517 struct GNUNET_DNSPARSER_Flags flags;
520 * DNS ID (to match replies to requests).
528 * Check if a label in UTF-8 format can be coded into valid IDNA.
529 * This can fail if the ASCII-conversion becomes longer than 63 characters.
531 * @param label label to check (UTF-8 string)
532 * @return GNUNET_OK if the label can be converted to IDNA,
533 * GNUNET_SYSERR if the label is not valid for DNS names
536 GNUNET_DNSPARSER_check_label (const char *label);
540 * Check if a hostname in UTF-8 format can be coded into valid IDNA.
541 * This can fail if a label becomes longer than 63 characters or if
542 * the entire name exceeds 253 characters.
544 * @param name name to check (UTF-8 string)
545 * @return GNUNET_OK if the label can be converted to IDNA,
546 * GNUNET_SYSERR if the label is not valid for DNS names
549 GNUNET_DNSPARSER_check_name (const char *name);
553 * Parse a UDP payload of a DNS packet in to a nice struct for further
554 * processing and manipulation.
556 * @param udp_payload wire-format of the DNS packet
557 * @param udp_payload_length number of bytes in udp_payload
558 * @return NULL on error, otherwise the parsed packet
560 struct GNUNET_DNSPARSER_Packet *
561 GNUNET_DNSPARSER_parse (const char *udp_payload,
562 size_t udp_payload_length);
566 * Free memory taken by a packet.
568 * @param p packet to free
571 GNUNET_DNSPARSER_free_packet (struct GNUNET_DNSPARSER_Packet *p);
575 * Given a DNS packet, generate the corresponding UDP payload.
577 * @param p packet to pack
578 * @param max maximum allowed size for the resulting UDP payload
579 * @param buf set to a buffer with the packed message
580 * @param buf_length set to the length of buf
581 * @return GNUNET_SYSERR if 'p' is invalid
582 * GNUNET_NO if 'p' was truncated (but there is still a result in 'buf')
583 * GNUNET_OK if 'p' was packed completely into '*buf'
586 GNUNET_DNSPARSER_pack (const struct GNUNET_DNSPARSER_Packet *p,