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+/*
+ * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+ *
+ * SPDX-License-Identifier: MPL-2.0
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, you can obtain one at https://mozilla.org/MPL/2.0/.
+ *
+ * See the COPYRIGHT file distributed with this work for additional
+ * information regarding copyright ownership.
+ */
+
+#pragma once
+
+/*****
+***** Module Info
+*****/
+
+/*! \file dns/rdata.h
+ * \brief
+ * Provides facilities for manipulating DNS rdata, including conversions to
+ * and from wire format and text format.
+ *
+ * Given the large amount of rdata possible in a nameserver, it was important
+ * to come up with a very efficient way of storing rdata, but at the same
+ * time allow it to be manipulated.
+ *
+ * The decision was to store rdata in uncompressed wire format,
+ * and not to make it a fully abstracted object; i.e. certain parts of the
+ * server know rdata is stored that way. This saves a lot of memory, and
+ * makes adding rdata to messages easy. Having much of the server know
+ * the representation would be perilous, and we certainly don't want each
+ * user of rdata to be manipulating such a low-level structure. This is
+ * where the rdata module comes in. The module allows rdata handles to be
+ * created and attached to uncompressed wire format regions. All rdata
+ * operations and conversions are done through these handles.
+ *
+ * Implementation Notes:
+ *
+ *\li The routines in this module are expected to be synthesized by the
+ * build process from a set of source files, one per rdata type. For
+ * portability, it's probably best that the building be done by a C
+ * program. Adding a new rdata type will be a simple matter of adding
+ * a file to a directory and rebuilding the server. *All* knowledge of
+ * the format of a particular rdata type is in this file.
+ *
+ * MP:
+ *\li Clients of this module must impose any required synchronization.
+ *
+ * Reliability:
+ *\li This module deals with low-level byte streams. Errors in any of
+ * the functions are likely to crash the server or corrupt memory.
+ *
+ *\li Rdata is typed, and the caller must know what type of rdata it has.
+ * A caller that gets this wrong could crash the server.
+ *
+ *\li The fromstruct() and tostruct() routines use a void * pointer to
+ * represent the structure. The caller must ensure that it passes a
+ * pointer to the appropriate type, or the server could crash or memory
+ * could be corrupted.
+ *
+ * Resources:
+ *\li None.
+ *
+ * Security:
+ *
+ *\li *** WARNING ***
+ * dns_rdata_fromwire() deals with raw network data. An error in
+ * this routine could result in the failure or hijacking of the server.
+ *
+ * Standards:
+ *\li RFC1035
+ *\li Draft EDNS0 (0)
+ *\li Draft EDNS1 (0)
+ *\li Draft Binary Labels (2)
+ *\li Draft Local Compression (1)
+ *\li Various RFCs for particular types; these will be documented in the
+ * sources files of the types.
+ *
+ */
+
+/***
+ *** Imports
+ ***/
+
+#include <stdbool.h>
+
+#include <isc/lang.h>
+
+#include <dns/message.h>
+#include <dns/name.h>
+#include <dns/types.h>
+
+ISC_LANG_BEGINDECLS
+
+/***
+ *** Types
+ ***/
+
+/*%
+ ***** An 'rdata' is a handle to a binary region. The handle has an RR
+ ***** class and type, and the data in the binary region is in the format
+ ***** of the given class and type.
+ *****/
+/*%
+ * Clients are strongly discouraged from using this type directly, with
+ * the exception of the 'link' field which may be used directly for whatever
+ * purpose the client desires.
+ */
+struct dns_rdata {
+ unsigned char *data;
+ unsigned int length;
+ dns_rdataclass_t rdclass;
+ dns_rdatatype_t type;
+ unsigned int flags;
+ ISC_LINK(dns_rdata_t) link;
+};
+
+#define DNS_RDATA_INIT \
+ { \
+ NULL, 0, 0, 0, 0, { (void *)(-1), (void *)(-1) } \
+ }
+
+#define DNS_RDATA_CHECKINITIALIZED
+#ifdef DNS_RDATA_CHECKINITIALIZED
+#define DNS_RDATA_INITIALIZED(rdata) \
+ ((rdata)->data == NULL && (rdata)->length == 0 && \
+ (rdata)->rdclass == 0 && (rdata)->type == 0 && (rdata)->flags == 0 && \
+ !ISC_LINK_LINKED((rdata), link))
+#else /* ifdef DNS_RDATA_CHECKINITIALIZED */
+#ifdef ISC_LIST_CHECKINIT
+#define DNS_RDATA_INITIALIZED(rdata) (!ISC_LINK_LINKED((rdata), link))
+#else /* ifdef ISC_LIST_CHECKINIT */
+#define DNS_RDATA_INITIALIZED(rdata) true
+#endif /* ifdef ISC_LIST_CHECKINIT */
+#endif /* ifdef DNS_RDATA_CHECKINITIALIZED */
+
+#define DNS_RDATA_UPDATE 0x0001 /*%< update pseudo record. */
+#define DNS_RDATA_OFFLINE 0x0002 /*%< RRSIG has a offline key. */
+
+#define DNS_RDATA_VALIDFLAGS(rdata) \
+ (((rdata)->flags & ~(DNS_RDATA_UPDATE | DNS_RDATA_OFFLINE)) == 0)
+
+/*
+ * The maximum length of a RDATA that can be sent on the wire.
+ * Max packet size (65535) less header (12), less name (1), type (2),
+ * class (2), ttl(4), length (2).
+ *
+ * None of the defined types that support name compression can exceed
+ * this and all new types are to be sent uncompressed.
+ */
+
+#define DNS_RDATA_MAXLENGTH 65512U
+
+/*
+ * Flags affecting rdata formatting style. Flags 0xFFFF0000
+ * are used by masterfile-level formatting and defined elsewhere.
+ * See additional comments at dns_rdata_tofmttext().
+ */
+
+/*% Split the rdata into multiple lines to try to keep it
+ * within the "width". */
+#define DNS_STYLEFLAG_MULTILINE 0x00000001ULL
+
+/*% Output explanatory comments. */
+#define DNS_STYLEFLAG_COMMENT 0x00000002ULL
+#define DNS_STYLEFLAG_RRCOMMENT 0x00000004ULL
+
+/*% Output KEYDATA in human readable format. */
+#define DNS_STYLEFLAG_KEYDATA 0x00000008ULL
+
+/*% Output textual RR type and RDATA in RFC 3597 unknown format */
+#define DNS_STYLEFLAG_UNKNOWNFORMAT 0x00000010ULL
+
+/*% Print AAAA record fully expanded */
+#define DNS_STYLEFLAG_EXPANDAAAA 0x00000020ULL
+
+#define DNS_RDATA_DOWNCASE DNS_NAME_DOWNCASE
+#define DNS_RDATA_CHECKNAMES DNS_NAME_CHECKNAMES
+#define DNS_RDATA_CHECKNAMESFAIL DNS_NAME_CHECKNAMESFAIL
+#define DNS_RDATA_CHECKREVERSE DNS_NAME_CHECKREVERSE
+#define DNS_RDATA_CHECKMX DNS_NAME_CHECKMX
+#define DNS_RDATA_CHECKMXFAIL DNS_NAME_CHECKMXFAIL
+#define DNS_RDATA_UNKNOWNESCAPE 0x80000000
+
+/***
+ *** Initialization
+ ***/
+
+void
+dns_rdata_init(dns_rdata_t *rdata);
+/*%<
+ * Make 'rdata' empty.
+ *
+ * Requires:
+ * 'rdata' is a valid rdata (i.e. not NULL, points to a struct dns_rdata)
+ */
+
+void
+dns_rdata_reset(dns_rdata_t *rdata);
+/*%<
+ * Make 'rdata' empty.
+ *
+ * Requires:
+ *\li 'rdata' is a previously initialized rdata and is not linked.
+ */
+
+void
+dns_rdata_clone(const dns_rdata_t *src, dns_rdata_t *target);
+/*%<
+ * Clone 'target' from 'src'.
+ *
+ * Requires:
+ *\li 'src' to be initialized.
+ *\li 'target' to be initialized.
+ */
+
+/***
+ *** Comparisons
+ ***/
+
+int
+dns_rdata_compare(const dns_rdata_t *rdata1, const dns_rdata_t *rdata2);
+/*%<
+ * Determine the relative ordering under the DNSSEC order relation of
+ * 'rdata1' and 'rdata2'.
+ *
+ * Requires:
+ *
+ *\li 'rdata1' is a valid, non-empty rdata
+ *
+ *\li 'rdata2' is a valid, non-empty rdata
+ *
+ * Returns:
+ *\li < 0 'rdata1' is less than 'rdata2'
+ *\li 0 'rdata1' is equal to 'rdata2'
+ *\li > 0 'rdata1' is greater than 'rdata2'
+ */
+
+int
+dns_rdata_casecompare(const dns_rdata_t *rdata1, const dns_rdata_t *rdata2);
+/*%<
+ * dns_rdata_casecompare() is similar to dns_rdata_compare() but also
+ * compares domain names case insensitively in known rdata types that
+ * are treated as opaque data by dns_rdata_compare().
+ *
+ * Requires:
+ *
+ *\li 'rdata1' is a valid, non-empty rdata
+ *
+ *\li 'rdata2' is a valid, non-empty rdata
+ *
+ * Returns:
+ *\li < 0 'rdata1' is less than 'rdata2'
+ *\li 0 'rdata1' is equal to 'rdata2'
+ *\li > 0 'rdata1' is greater than 'rdata2'
+ */
+
+/***
+ *** Conversions
+ ***/
+
+void
+dns_rdata_fromregion(dns_rdata_t *rdata, dns_rdataclass_t rdclass,
+ dns_rdatatype_t type, isc_region_t *r);
+/*%<
+ * Make 'rdata' refer to region 'r'.
+ *
+ * Requires:
+ *
+ *\li The data in 'r' is properly formatted for whatever type it is.
+ */
+
+void
+dns_rdata_toregion(const dns_rdata_t *rdata, isc_region_t *r);
+/*%<
+ * Make 'r' refer to 'rdata'.
+ */
+
+isc_result_t
+dns_rdata_fromwire(dns_rdata_t *rdata, dns_rdataclass_t rdclass,
+ dns_rdatatype_t type, isc_buffer_t *source,
+ dns_decompress_t *dctx, unsigned int options,
+ isc_buffer_t *target);
+/*%<
+ * Copy the possibly-compressed rdata at source into the target region.
+ *
+ * Notes:
+ *\li Name decompression policy is controlled by 'dctx'.
+ *
+ * 'options'
+ *\li DNS_RDATA_DOWNCASE downcase domain names when they are copied
+ * into target.
+ *
+ * Requires:
+ *
+ *\li 'rdclass' and 'type' are valid.
+ *
+ *\li 'source' is a valid buffer, and the active region of 'source'
+ * references the rdata to be processed.
+ *
+ *\li 'target' is a valid buffer.
+ *
+ *\li 'dctx' is a valid decompression context.
+ *
+ * Ensures,
+ * if result is success:
+ * \li If 'rdata' is not NULL, it is attached to the target.
+ * \li The conditions dns_name_fromwire() ensures for names hold
+ * for all names in the rdata.
+ * \li The current location in source is advanced, and the used space
+ * in target is updated.
+ *
+ * Result:
+ *\li Success
+ *\li Any non-success status from dns_name_fromwire()
+ *\li Various 'Bad Form' class failures depending on class and type
+ *\li Bad Form: Input too short
+ *\li Resource Limit: Not enough space
+ */
+
+isc_result_t
+dns_rdata_towire(dns_rdata_t *rdata, dns_compress_t *cctx,
+ isc_buffer_t *target);
+/*%<
+ * Convert 'rdata' into wire format, compressing it as specified by the
+ * compression context 'cctx', and storing the result in 'target'.
+ *
+ * Notes:
+ *\li If the compression context allows global compression, then the
+ * global compression table may be updated.
+ *
+ * Requires:
+ *\li 'rdata' is a valid, non-empty rdata
+ *
+ *\li target is a valid buffer
+ *
+ *\li Any offsets specified in a global compression table are valid
+ * for target.
+ *
+ * Ensures,
+ * if the result is success:
+ * \li The used space in target is updated.
+ *
+ * Returns:
+ *\li Success
+ *\li Any non-success status from dns_name_towire()
+ *\li Resource Limit: Not enough space
+ */
+
+isc_result_t
+dns_rdata_fromtext(dns_rdata_t *rdata, dns_rdataclass_t rdclass,
+ dns_rdatatype_t type, isc_lex_t *lexer,
+ const dns_name_t *origin, unsigned int options,
+ isc_mem_t *mctx, isc_buffer_t *target,
+ dns_rdatacallbacks_t *callbacks);
+/*%<
+ * Convert the textual representation of a DNS rdata into uncompressed wire
+ * form stored in the target region. Tokens constituting the text of the rdata
+ * are taken from 'lexer'.
+ *
+ * Notes:
+ *\li Relative domain names in the rdata will have 'origin' appended to them.
+ * A NULL origin implies "origin == dns_rootname".
+ *
+ *
+ * 'options'
+ *\li DNS_RDATA_DOWNCASE downcase domain names when they are copied
+ * into target.
+ *\li DNS_RDATA_CHECKNAMES perform checknames checks.
+ *\li DNS_RDATA_CHECKNAMESFAIL fail if the checknames check fail. If
+ * not set a warning will be issued.
+ *\li DNS_RDATA_CHECKREVERSE this should set if the owner name ends
+ * in IP6.ARPA, IP6.INT or IN-ADDR.ARPA.
+ *
+ * Requires:
+ *
+ *\li 'rdclass' and 'type' are valid.
+ *
+ *\li 'lexer' is a valid isc_lex_t.
+ *
+ *\li 'mctx' is a valid isc_mem_t.
+ *
+ *\li 'target' is a valid region.
+ *
+ *\li 'origin' if non NULL it must be absolute.
+ *
+ *\li 'callbacks' to be NULL or callbacks->warn and callbacks->error be
+ * initialized.
+ *
+ * Ensures,
+ * if result is success:
+ *\li If 'rdata' is not NULL, it is attached to the target.
+ *
+ *\li The conditions dns_name_fromtext() ensures for names hold
+ * for all names in the rdata.
+ *
+ *\li The used space in target is updated.
+ *
+ * Result:
+ *\li Success
+ *\li Translated result codes from isc_lex_gettoken
+ *\li Various 'Bad Form' class failures depending on class and type
+ *\li Bad Form: Input too short
+ *\li Resource Limit: Not enough space
+ *\li Resource Limit: Not enough memory
+ */
+
+isc_result_t
+dns_rdata_totext(dns_rdata_t *rdata, const dns_name_t *origin,
+ isc_buffer_t *target);
+/*%<
+ * Convert 'rdata' into text format, storing the result in 'target'.
+ * The text will consist of a single line, with fields separated by
+ * single spaces.
+ *
+ * Notes:
+ *\li If 'origin' is not NULL, then any names in the rdata that are
+ * subdomains of 'origin' will be made relative it.
+ *
+ *\li XXX Do we *really* want to support 'origin'? I'm inclined towards "no"
+ * at the moment.
+ *
+ * Requires:
+ *
+ *\li 'rdata' is a valid, non-empty rdata
+ *
+ *\li 'origin' is NULL, or is a valid name
+ *
+ *\li 'target' is a valid text buffer
+ *
+ * Ensures,
+ * if the result is success:
+ *
+ * \li The used space in target is updated.
+ *
+ * Returns:
+ *\li Success
+ *\li Any non-success status from dns_name_totext()
+ *\li Resource Limit: Not enough space
+ */
+
+isc_result_t
+dns_rdata_tofmttext(dns_rdata_t *rdata, const dns_name_t *origin,
+ dns_masterstyle_flags_t flags, unsigned int width,
+ unsigned int split_width, const char *linebreak,
+ isc_buffer_t *target);
+/*%<
+ * Like dns_rdata_totext, but do formatted output suitable for
+ * database dumps. This is intended for use by dns_db_dump();
+ * library users are discouraged from calling it directly.
+ *
+ * If (flags & #DNS_STYLEFLAG_MULTILINE) != 0, attempt to stay
+ * within 'width' by breaking the text into multiple lines.
+ * The string 'linebreak' is inserted between lines, and parentheses
+ * are added when necessary. Because RRs contain unbreakable elements
+ * such as domain names whose length is variable, unpredictable, and
+ * potentially large, there is no guarantee that the lines will
+ * not exceed 'width' anyway.
+ *
+ * If (flags & #DNS_STYLEFLAG_MULTILINE) == 0, the rdata is always
+ * printed as a single line, and no parentheses are used.
+ * The 'width' and 'linebreak' arguments are ignored.
+ *
+ * If (flags & #DNS_STYLEFLAG_COMMENT) != 0, output explanatory
+ * comments next to things like the SOA timer fields. Some
+ * comments (e.g., the SOA ones) are only printed when multiline
+ * output is selected.
+ *
+ * base64 rdata text (e.g., DNSKEY records) will be split into chunks
+ * of 'split_width' characters. If split_width == 0, the text will
+ * not be split at all. If split_width == UINT_MAX (0xffffffff), then
+ * it is undefined and falls back to the default value of 'width'
+ */
+
+isc_result_t
+dns_rdata_fromstruct(dns_rdata_t *rdata, dns_rdataclass_t rdclass,
+ dns_rdatatype_t type, void *source, isc_buffer_t *target);
+/*%<
+ * Convert the C structure representation of an rdata into uncompressed wire
+ * format in 'target'.
+ *
+ * XXX Should we have a 'size' parameter as a sanity check on target?
+ *
+ * Requires:
+ *
+ *\li 'rdclass' and 'type' are valid.
+ *
+ *\li 'source' points to a valid C struct for the class and type.
+ *
+ *\li 'target' is a valid buffer.
+ *
+ *\li All structure pointers to memory blocks should be NULL if their
+ * corresponding length values are zero.
+ *
+ * Ensures,
+ * if result is success:
+ * \li If 'rdata' is not NULL, it is attached to the target.
+ *
+ * \li The used space in 'target' is updated.
+ *
+ * Result:
+ *\li Success
+ *\li Various 'Bad Form' class failures depending on class and type
+ *\li Resource Limit: Not enough space
+ */
+
+isc_result_t
+dns_rdata_tostruct(const dns_rdata_t *rdata, void *target, isc_mem_t *mctx);
+/*%<
+ * Convert an rdata into its C structure representation.
+ *
+ * If 'mctx' is NULL then 'rdata' must persist while 'target' is being used.
+ *
+ * If 'mctx' is non NULL then memory will be allocated if required.
+ *
+ * Requires:
+ *
+ *\li 'rdata' is a valid, non-empty, non-pseudo rdata.
+ *
+ *\li 'target' to point to a valid pointer for the type and class.
+ *
+ * Result:
+ *\li Success
+ *\li Resource Limit: Not enough memory
+ */
+
+void
+dns_rdata_freestruct(void *source);
+/*%<
+ * Free dynamic memory attached to 'source' (if any).
+ *
+ * Requires:
+ *
+ *\li 'source' to point to the structure previously filled in by
+ * dns_rdata_tostruct().
+ */
+
+bool
+dns_rdatatype_ismeta(dns_rdatatype_t type);
+/*%<
+ * Return true iff the rdata type 'type' is a meta-type
+ * like ANY or AXFR.
+ */
+
+bool
+dns_rdatatype_issingleton(dns_rdatatype_t type);
+/*%<
+ * Return true iff the rdata type 'type' is a singleton type,
+ * like CNAME or SOA.
+ *
+ * Requires:
+ * \li 'type' is a valid rdata type.
+ *
+ */
+
+bool
+dns_rdataclass_ismeta(dns_rdataclass_t rdclass);
+/*%<
+ * Return true iff the rdata class 'rdclass' is a meta-class
+ * like ANY or NONE.
+ */
+
+bool
+dns_rdatatype_isdnssec(dns_rdatatype_t type);
+/*%<
+ * Return true iff 'type' is one of the DNSSEC
+ * rdata types that may exist alongside a CNAME record.
+ *
+ * Requires:
+ * \li 'type' is a valid rdata type.
+ */
+
+bool
+dns_rdatatype_iszonecutauth(dns_rdatatype_t type);
+/*%<
+ * Return true iff rdata of type 'type' is considered authoritative
+ * data (not glue) in the NSEC chain when it occurs in the parent zone
+ * at a zone cut.
+ *
+ * Requires:
+ * \li 'type' is a valid rdata type.
+ *
+ */
+
+bool
+dns_rdatatype_isknown(dns_rdatatype_t type);
+/*%<
+ * Return true iff the rdata type 'type' is known.
+ *
+ * Requires:
+ * \li 'type' is a valid rdata type.
+ *
+ */
+
+isc_result_t
+dns_rdata_additionaldata(dns_rdata_t *rdata, const dns_name_t *owner,
+ dns_additionaldatafunc_t add, void *arg);
+/*%<
+ * Call 'add' for each name and type from 'rdata' which is subject to
+ * additional section processing.
+ *
+ * Requires:
+ *
+ *\li 'rdata' is a valid, non-empty rdata.
+ *
+ *\li 'add' is a valid dns_additionalfunc_t.
+ *
+ * Ensures:
+ *
+ *\li If successful, then add() will have been called for each name
+ * and type subject to additional section processing.
+ *
+ *\li If add() returns something other than #ISC_R_SUCCESS, that result
+ * will be returned as the result of dns_rdata_additionaldata().
+ *
+ * Returns:
+ *
+ *\li ISC_R_SUCCESS
+ *
+ *\li Many other results are possible if not successful.
+ */
+
+isc_result_t
+dns_rdata_digest(dns_rdata_t *rdata, dns_digestfunc_t digest, void *arg);
+/*%<
+ * Send 'rdata' in DNSSEC canonical form to 'digest'.
+ *
+ * Note:
+ *\li 'digest' may be called more than once by dns_rdata_digest(). The
+ * concatenation of all the regions, in the order they were given
+ * to 'digest', will be the DNSSEC canonical form of 'rdata'.
+ *
+ * Requires:
+ *
+ *\li 'rdata' is a valid, non-empty rdata.
+ *
+ *\li 'digest' is a valid dns_digestfunc_t.
+ *
+ * Ensures:
+ *
+ *\li If successful, then all of the rdata's data has been sent, in
+ * DNSSEC canonical form, to 'digest'.
+ *
+ *\li If digest() returns something other than ISC_R_SUCCESS, that result
+ * will be returned as the result of dns_rdata_digest().
+ *
+ * Returns:
+ *
+ *\li ISC_R_SUCCESS
+ *
+ *\li Many other results are possible if not successful.
+ */
+
+bool
+dns_rdatatype_questiononly(dns_rdatatype_t type);
+/*%<
+ * Return true iff rdata of type 'type' can only appear in the question
+ * section of a properly formatted message.
+ *
+ * Requires:
+ * \li 'type' is a valid rdata type.
+ *
+ */
+
+bool
+dns_rdatatype_notquestion(dns_rdatatype_t type);
+/*%<
+ * Return true iff rdata of type 'type' can not appear in the question
+ * section of a properly formatted message.
+ *
+ * Requires:
+ * \li 'type' is a valid rdata type.
+ *
+ */
+
+bool
+dns_rdatatype_atparent(dns_rdatatype_t type);
+/*%<
+ * Return true iff rdata of type 'type' should appear at the parent of
+ * a zone cut.
+ *
+ * Requires:
+ * \li 'type' is a valid rdata type.
+ *
+ */
+
+bool
+dns_rdatatype_atcname(dns_rdatatype_t type);
+/*%<
+ * Return true iff rdata of type 'type' can appear beside a cname.
+ *
+ * Requires:
+ * \li 'type' is a valid rdata type.
+ *
+ */
+
+bool
+dns_rdatatype_followadditional(dns_rdatatype_t type);
+/*%<
+ * Return true if adding a record of type 'type' to the ADDITIONAL section
+ * of a message can itself trigger the addition of still more data to the
+ * additional section.
+ *
+ * (For example: adding SRV to the ADDITIONAL section may trigger
+ * the addition of address records associated with that SRV.)
+ *
+ * Requires:
+ * \li 'type' is a valid rdata type.
+ *
+ */
+
+unsigned int
+dns_rdatatype_attributes(dns_rdatatype_t rdtype);
+/*%<
+ * Return attributes for the given type.
+ *
+ * Requires:
+ *\li 'rdtype' are known.
+ *
+ * Returns:
+ *\li a bitmask consisting of the following flags.
+ */
+
+/*% only one may exist for a name */
+#define DNS_RDATATYPEATTR_SINGLETON 0x00000001U
+/*% requires no other data be present */
+#define DNS_RDATATYPEATTR_EXCLUSIVE 0x00000002U
+/*% Is a meta type */
+#define DNS_RDATATYPEATTR_META 0x00000004U
+/*% Is a DNSSEC type, like RRSIG or NSEC */
+#define DNS_RDATATYPEATTR_DNSSEC 0x00000008U
+/*% Is a zone cut authority type */
+#define DNS_RDATATYPEATTR_ZONECUTAUTH 0x00000010U
+/*% Is reserved (unusable) */
+#define DNS_RDATATYPEATTR_RESERVED 0x00000020U
+/*% Is an unknown type */
+#define DNS_RDATATYPEATTR_UNKNOWN 0x00000040U
+/*% Is META, and can only be in a question section */
+#define DNS_RDATATYPEATTR_QUESTIONONLY 0x00000080U
+/*% Is META, and can NOT be in a question section */
+#define DNS_RDATATYPEATTR_NOTQUESTION 0x00000100U
+/*% Is present at zone cuts in the parent, not the child */
+#define DNS_RDATATYPEATTR_ATPARENT 0x00000200U
+/*% Can exist along side a CNAME */
+#define DNS_RDATATYPEATTR_ATCNAME 0x00000400U
+/*% Follow additional */
+#define DNS_RDATATYPEATTR_FOLLOWADDITIONAL 0x00000800U
+
+dns_rdatatype_t
+dns_rdata_covers(dns_rdata_t *rdata);
+/*%<
+ * Return the rdatatype that this type covers.
+ *
+ * Requires:
+ *\li 'rdata' is a valid, non-empty rdata.
+ *
+ *\li 'rdata' is a type that covers other rdata types.
+ *
+ * Returns:
+ *\li The type covered.
+ */
+
+bool
+dns_rdata_checkowner(const dns_name_t *name, dns_rdataclass_t rdclass,
+ dns_rdatatype_t type, bool wildcard);
+/*
+ * Returns whether this is a valid ownername for this <type,class>.
+ * If wildcard is true allow the first label to be a wildcard if
+ * appropriate.
+ *
+ * Requires:
+ * 'name' is a valid name.
+ */
+
+bool
+dns_rdata_checknames(dns_rdata_t *rdata, const dns_name_t *owner,
+ dns_name_t *bad);
+/*
+ * Returns whether 'rdata' contains valid domain names. The checks are
+ * sensitive to the owner name.
+ *
+ * If 'bad' is non-NULL and a domain name fails the check the
+ * the offending name will be return in 'bad' by cloning from
+ * the 'rdata' contents.
+ *
+ * Requires:
+ * 'rdata' to be valid.
+ * 'owner' to be valid.
+ * 'bad' to be NULL or valid.
+ */
+
+void
+dns_rdata_exists(dns_rdata_t *rdata, dns_rdatatype_t type);
+
+void
+dns_rdata_notexist(dns_rdata_t *rdata, dns_rdatatype_t type);
+
+void
+dns_rdata_deleterrset(dns_rdata_t *rdata, dns_rdatatype_t type);
+
+void
+dns_rdata_makedelete(dns_rdata_t *rdata);
+
+const char *
+dns_rdata_updateop(dns_rdata_t *rdata, dns_section_t section);
+
+ISC_LANG_ENDDECLS