2 * Copyright (C) 2004-2009 Internet Systems Consortium, Inc. ("ISC")
3 * Copyright (C) 1998-2003 Internet Software Consortium.
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18 /* $Id: rdata.h,v 1.70.120.3 2009/02/16 00:29:27 marka Exp $ */
29 * Provides facilities for manipulating DNS rdata, including conversions to
30 * and from wire format and text format.
32 * Given the large amount of rdata possible in a nameserver, it was important
33 * to come up with a very efficient way of storing rdata, but at the same
34 * time allow it to be manipulated.
36 * The decision was to store rdata in uncompressed wire format,
37 * and not to make it a fully abstracted object; i.e. certain parts of the
38 * server know rdata is stored that way. This saves a lot of memory, and
39 * makes adding rdata to messages easy. Having much of the server know
40 * the representation would be perilous, and we certainly don't want each
41 * user of rdata to be manipulating such a low-level structure. This is
42 * where the rdata module comes in. The module allows rdata handles to be
43 * created and attached to uncompressed wire format regions. All rdata
44 * operations and conversions are done through these handles.
46 * Implementation Notes:
48 *\li The routines in this module are expected to be synthesized by the
49 * build process from a set of source files, one per rdata type. For
50 * portability, it's probably best that the building be done by a C
51 * program. Adding a new rdata type will be a simple matter of adding
52 * a file to a directory and rebuilding the server. *All* knowledge of
53 * the format of a particular rdata type is in this file.
56 *\li Clients of this module must impose any required synchronization.
59 *\li This module deals with low-level byte streams. Errors in any of
60 * the functions are likely to crash the server or corrupt memory.
62 *\li Rdata is typed, and the caller must know what type of rdata it has.
63 * A caller that gets this wrong could crash the server.
65 *\li The fromstruct() and tostruct() routines use a void * pointer to
66 * represent the structure. The caller must ensure that it passes a
67 * pointer to the appropriate type, or the server could crash or memory
76 * dns_rdata_fromwire() deals with raw network data. An error in
77 * this routine could result in the failure or hijacking of the server.
83 *\li Draft Binary Labels (2)
84 *\li Draft Local Compression (1)
85 *\li Various RFCs for particular types; these will be documented in the
86 * sources files of the types.
96 #include <dns/types.h>
107 ***** An 'rdata' is a handle to a binary region. The handle has an RR
108 ***** class and type, and the data in the binary region is in the format
109 ***** of the given class and type.
112 * Clients are strongly discouraged from using this type directly, with
113 * the exception of the 'link' field which may be used directly for whatever
114 * purpose the client desires.
117 unsigned char * data;
119 dns_rdataclass_t rdclass;
120 dns_rdatatype_t type;
122 ISC_LINK(dns_rdata_t) link;
125 #define DNS_RDATA_INIT { NULL, 0, 0, 0, 0, {(void*)(-1), (void *)(-1)}}
127 #define DNS_RDATA_UPDATE 0x0001 /*%< update pseudo record. */
128 #define DNS_RDATA_OFFLINE 0x0002 /*%< RRSIG has a offline key. */
131 * Flags affecting rdata formatting style. Flags 0xFFFF0000
132 * are used by masterfile-level formatting and defined elsewhere.
133 * See additional comments at dns_rdata_tofmttext().
136 /*% Split the rdata into multiple lines to try to keep it
137 within the "width". */
138 #define DNS_STYLEFLAG_MULTILINE 0x00000001U
140 /*% Output explanatory comments. */
141 #define DNS_STYLEFLAG_COMMENT 0x00000002U
143 #define DNS_RDATA_DOWNCASE DNS_NAME_DOWNCASE
144 #define DNS_RDATA_CHECKNAMES DNS_NAME_CHECKNAMES
145 #define DNS_RDATA_CHECKNAMESFAIL DNS_NAME_CHECKNAMESFAIL
146 #define DNS_RDATA_CHECKREVERSE DNS_NAME_CHECKREVERSE
147 #define DNS_RDATA_CHECKMX DNS_NAME_CHECKMX
148 #define DNS_RDATA_CHECKMXFAIL DNS_NAME_CHECKMXFAIL
155 dns_rdata_init(dns_rdata_t *rdata);
157 * Make 'rdata' empty.
160 * 'rdata' is a valid rdata (i.e. not NULL, points to a struct dns_rdata)
164 dns_rdata_reset(dns_rdata_t *rdata);
166 * Make 'rdata' empty.
169 *\li 'rdata' is a previously initialized rdata and is not linked.
173 dns_rdata_clone(const dns_rdata_t *src, dns_rdata_t *target);
175 * Clone 'target' from 'src'.
178 *\li 'src' to be initialized.
179 *\li 'target' to be initialized.
187 dns_rdata_compare(const dns_rdata_t *rdata1, const dns_rdata_t *rdata2);
189 * Determine the relative ordering under the DNSSEC order relation of
190 * 'rdata1' and 'rdata2'.
194 *\li 'rdata1' is a valid, non-empty rdata
196 *\li 'rdata2' is a valid, non-empty rdata
199 *\li < 0 'rdata1' is less than 'rdata2'
200 *\li 0 'rdata1' is equal to 'rdata2'
201 *\li > 0 'rdata1' is greater than 'rdata2'
209 dns_rdata_fromregion(dns_rdata_t *rdata, dns_rdataclass_t rdclass,
210 dns_rdatatype_t type, isc_region_t *r);
212 * Make 'rdata' refer to region 'r'.
216 *\li The data in 'r' is properly formatted for whatever type it is.
220 dns_rdata_toregion(const dns_rdata_t *rdata, isc_region_t *r);
222 * Make 'r' refer to 'rdata'.
226 dns_rdata_fromwire(dns_rdata_t *rdata, dns_rdataclass_t rdclass,
227 dns_rdatatype_t type, isc_buffer_t *source,
228 dns_decompress_t *dctx, unsigned int options,
229 isc_buffer_t *target);
231 * Copy the possibly-compressed rdata at source into the target region.
234 *\li Name decompression policy is controlled by 'dctx'.
237 *\li DNS_RDATA_DOWNCASE downcase domain names when they are copied
242 *\li 'rdclass' and 'type' are valid.
244 *\li 'source' is a valid buffer, and the active region of 'source'
245 * references the rdata to be processed.
247 *\li 'target' is a valid buffer.
249 *\li 'dctx' is a valid decompression context.
252 * if result is success:
253 * \li If 'rdata' is not NULL, it is attached to the target.
254 * \li The conditions dns_name_fromwire() ensures for names hold
255 * for all names in the rdata.
256 * \li The current location in source is advanced, and the used space
257 * in target is updated.
261 *\li Any non-success status from dns_name_fromwire()
262 *\li Various 'Bad Form' class failures depending on class and type
263 *\li Bad Form: Input too short
264 *\li Resource Limit: Not enough space
268 dns_rdata_towire(dns_rdata_t *rdata, dns_compress_t *cctx,
269 isc_buffer_t *target);
271 * Convert 'rdata' into wire format, compressing it as specified by the
272 * compression context 'cctx', and storing the result in 'target'.
275 *\li If the compression context allows global compression, then the
276 * global compression table may be updated.
279 *\li 'rdata' is a valid, non-empty rdata
281 *\li target is a valid buffer
283 *\li Any offsets specified in a global compression table are valid
287 * if the result is success:
288 * \li The used space in target is updated.
292 *\li Any non-success status from dns_name_towire()
293 *\li Resource Limit: Not enough space
297 dns_rdata_fromtext(dns_rdata_t *rdata, dns_rdataclass_t rdclass,
298 dns_rdatatype_t type, isc_lex_t *lexer, dns_name_t *origin,
299 unsigned int options, isc_mem_t *mctx,
300 isc_buffer_t *target, dns_rdatacallbacks_t *callbacks);
302 * Convert the textual representation of a DNS rdata into uncompressed wire
303 * form stored in the target region. Tokens constituting the text of the rdata
304 * are taken from 'lexer'.
307 *\li Relative domain names in the rdata will have 'origin' appended to them.
308 * A NULL origin implies "origin == dns_rootname".
312 *\li DNS_RDATA_DOWNCASE downcase domain names when they are copied
314 *\li DNS_RDATA_CHECKNAMES perform checknames checks.
315 *\li DNS_RDATA_CHECKNAMESFAIL fail if the checknames check fail. If
316 * not set a warning will be issued.
317 *\li DNS_RDATA_CHECKREVERSE this should set if the owner name ends
318 * in IP6.ARPA, IP6.INT or IN-ADDR.ARPA.
322 *\li 'rdclass' and 'type' are valid.
324 *\li 'lexer' is a valid isc_lex_t.
326 *\li 'mctx' is a valid isc_mem_t.
328 *\li 'target' is a valid region.
330 *\li 'origin' if non NULL it must be absolute.
332 *\li 'callbacks' to be NULL or callbacks->warn and callbacks->error be
336 * if result is success:
337 *\li If 'rdata' is not NULL, it is attached to the target.
339 *\li The conditions dns_name_fromtext() ensures for names hold
340 * for all names in the rdata.
342 *\li The used space in target is updated.
346 *\li Translated result codes from isc_lex_gettoken
347 *\li Various 'Bad Form' class failures depending on class and type
348 *\li Bad Form: Input too short
349 *\li Resource Limit: Not enough space
350 *\li Resource Limit: Not enough memory
354 dns_rdata_totext(dns_rdata_t *rdata, dns_name_t *origin, isc_buffer_t *target);
356 * Convert 'rdata' into text format, storing the result in 'target'.
357 * The text will consist of a single line, with fields separated by
361 *\li If 'origin' is not NULL, then any names in the rdata that are
362 * subdomains of 'origin' will be made relative it.
364 *\li XXX Do we *really* want to support 'origin'? I'm inclined towards "no"
369 *\li 'rdata' is a valid, non-empty rdata
371 *\li 'origin' is NULL, or is a valid name
373 *\li 'target' is a valid text buffer
376 * if the result is success:
378 * \li The used space in target is updated.
382 *\li Any non-success status from dns_name_totext()
383 *\li Resource Limit: Not enough space
387 dns_rdata_tofmttext(dns_rdata_t *rdata, dns_name_t *origin, unsigned int flags,
388 unsigned int width, const char *linebreak,
389 isc_buffer_t *target);
391 * Like dns_rdata_totext, but do formatted output suitable for
392 * database dumps. This is intended for use by dns_db_dump();
393 * library users are discouraged from calling it directly.
395 * If (flags & #DNS_STYLEFLAG_MULTILINE) != 0, attempt to stay
396 * within 'width' by breaking the text into multiple lines.
397 * The string 'linebreak' is inserted between lines, and parentheses
398 * are added when necessary. Because RRs contain unbreakable elements
399 * such as domain names whose length is variable, unpredictable, and
400 * potentially large, there is no guarantee that the lines will
401 * not exceed 'width' anyway.
403 * If (flags & #DNS_STYLEFLAG_MULTILINE) == 0, the rdata is always
404 * printed as a single line, and no parentheses are used.
405 * The 'width' and 'linebreak' arguments are ignored.
407 * If (flags & #DNS_STYLEFLAG_COMMENT) != 0, output explanatory
408 * comments next to things like the SOA timer fields. Some
409 * comments (e.g., the SOA ones) are only printed when multiline
410 * output is selected.
414 dns_rdata_fromstruct(dns_rdata_t *rdata, dns_rdataclass_t rdclass,
415 dns_rdatatype_t type, void *source, isc_buffer_t *target);
417 * Convert the C structure representation of an rdata into uncompressed wire
418 * format in 'target'.
420 * XXX Should we have a 'size' parameter as a sanity check on target?
424 *\li 'rdclass' and 'type' are valid.
426 *\li 'source' points to a valid C struct for the class and type.
428 *\li 'target' is a valid buffer.
430 *\li All structure pointers to memory blocks should be NULL if their
431 * corresponding length values are zero.
434 * if result is success:
435 * \li If 'rdata' is not NULL, it is attached to the target.
437 * \li The used space in 'target' is updated.
441 *\li Various 'Bad Form' class failures depending on class and type
442 *\li Resource Limit: Not enough space
446 dns_rdata_tostruct(dns_rdata_t *rdata, void *target, isc_mem_t *mctx);
448 * Convert an rdata into its C structure representation.
450 * If 'mctx' is NULL then 'rdata' must persist while 'target' is being used.
452 * If 'mctx' is non NULL then memory will be allocated if required.
456 *\li 'rdata' is a valid, non-empty rdata.
458 *\li 'target' to point to a valid pointer for the type and class.
462 *\li Resource Limit: Not enough memory
466 dns_rdata_freestruct(void *source);
468 * Free dynamic memory attached to 'source' (if any).
472 *\li 'source' to point to the structure previously filled in by
473 * dns_rdata_tostruct().
477 dns_rdatatype_ismeta(dns_rdatatype_t type);
479 * Return true iff the rdata type 'type' is a meta-type
484 dns_rdatatype_issingleton(dns_rdatatype_t type);
486 * Return true iff the rdata type 'type' is a singleton type,
490 * \li 'type' is a valid rdata type.
495 dns_rdataclass_ismeta(dns_rdataclass_t rdclass);
497 * Return true iff the rdata class 'rdclass' is a meta-class
502 dns_rdatatype_isdnssec(dns_rdatatype_t type);
504 * Return true iff 'type' is one of the DNSSEC
505 * rdata types that may exist alongside a CNAME record.
508 * \li 'type' is a valid rdata type.
512 dns_rdatatype_iszonecutauth(dns_rdatatype_t type);
514 * Return true iff rdata of type 'type' is considered authoritative
515 * data (not glue) in the NSEC chain when it occurs in the parent zone
519 * \li 'type' is a valid rdata type.
524 dns_rdatatype_isknown(dns_rdatatype_t type);
526 * Return true iff the rdata type 'type' is known.
529 * \li 'type' is a valid rdata type.
535 dns_rdata_additionaldata(dns_rdata_t *rdata, dns_additionaldatafunc_t add,
538 * Call 'add' for each name and type from 'rdata' which is subject to
539 * additional section processing.
543 *\li 'rdata' is a valid, non-empty rdata.
545 *\li 'add' is a valid dns_additionalfunc_t.
549 *\li If successful, then add() will have been called for each name
550 * and type subject to additional section processing.
552 *\li If add() returns something other than #ISC_R_SUCCESS, that result
553 * will be returned as the result of dns_rdata_additionaldata().
559 *\li Many other results are possible if not successful.
563 dns_rdata_digest(dns_rdata_t *rdata, dns_digestfunc_t digest, void *arg);
565 * Send 'rdata' in DNSSEC canonical form to 'digest'.
568 *\li 'digest' may be called more than once by dns_rdata_digest(). The
569 * concatenation of all the regions, in the order they were given
570 * to 'digest', will be the DNSSEC canonical form of 'rdata'.
574 *\li 'rdata' is a valid, non-empty rdata.
576 *\li 'digest' is a valid dns_digestfunc_t.
580 *\li If successful, then all of the rdata's data has been sent, in
581 * DNSSEC canonical form, to 'digest'.
583 *\li If digest() returns something other than ISC_R_SUCCESS, that result
584 * will be returned as the result of dns_rdata_digest().
590 *\li Many other results are possible if not successful.
594 dns_rdatatype_questiononly(dns_rdatatype_t type);
596 * Return true iff rdata of type 'type' can only appear in the question
597 * section of a properly formatted message.
600 * \li 'type' is a valid rdata type.
605 dns_rdatatype_notquestion(dns_rdatatype_t type);
607 * Return true iff rdata of type 'type' can not appear in the question
608 * section of a properly formatted message.
611 * \li 'type' is a valid rdata type.
616 dns_rdatatype_atparent(dns_rdatatype_t type);
618 * Return true iff rdata of type 'type' should appear at the parent of
622 * \li 'type' is a valid rdata type.
627 dns_rdatatype_attributes(dns_rdatatype_t rdtype);
629 * Return attributes for the given type.
632 *\li 'rdtype' are known.
635 *\li a bitmask consisting of the following flags.
638 /*% only one may exist for a name */
639 #define DNS_RDATATYPEATTR_SINGLETON 0x00000001U
640 /*% requires no other data be present */
641 #define DNS_RDATATYPEATTR_EXCLUSIVE 0x00000002U
642 /*% Is a meta type */
643 #define DNS_RDATATYPEATTR_META 0x00000004U
644 /*% Is a DNSSEC type, like RRSIG or NSEC */
645 #define DNS_RDATATYPEATTR_DNSSEC 0x00000008U
646 /*% Is a zone cut authority type */
647 #define DNS_RDATATYPEATTR_ZONECUTAUTH 0x00000010U
648 /*% Is reserved (unusable) */
649 #define DNS_RDATATYPEATTR_RESERVED 0x00000020U
650 /*% Is an unknown type */
651 #define DNS_RDATATYPEATTR_UNKNOWN 0x00000040U
652 /*% Is META, and can only be in a question section */
653 #define DNS_RDATATYPEATTR_QUESTIONONLY 0x00000080U
654 /*% is META, and can NOT be in a question section */
655 #define DNS_RDATATYPEATTR_NOTQUESTION 0x00000100U
656 /*% Is present at zone cuts in the parent, not the child */
657 #define DNS_RDATATYPEATTR_ATPARENT 0x00000200U
660 dns_rdata_covers(dns_rdata_t *rdata);
662 * Return the rdatatype that this type covers.
665 *\li 'rdata' is a valid, non-empty rdata.
667 *\li 'rdata' is a type that covers other rdata types.
670 *\li The type covered.
674 dns_rdata_checkowner(dns_name_t* name, dns_rdataclass_t rdclass,
675 dns_rdatatype_t type, isc_boolean_t wildcard);
677 * Returns whether this is a valid ownername for this <type,class>.
678 * If wildcard is true allow the first label to be a wildcard if
682 * 'name' is a valid name.
686 dns_rdata_checknames(dns_rdata_t *rdata, dns_name_t *owner, dns_name_t *bad);
688 * Returns whether 'rdata' contains valid domain names. The checks are
689 * sensitive to the owner name.
691 * If 'bad' is non-NULL and a domain name fails the check the
692 * the offending name will be return in 'bad' by cloning from
693 * the 'rdata' contents.
696 * 'rdata' to be valid.
697 * 'owner' to be valid.
698 * 'bad' to be NULL or valid.
703 #endif /* DNS_RDATA_H */