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/*
* Copyright (C) Internet Systems Consortium, Inc. ("ISC")
*
* 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.
*/
#ifndef DNS_RDATA_H
#define DNS_RDATA_H 1
/*****
***** 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/types.h>
#include <dns/name.h>
#include <dns/message.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 ISC_LIST_CHECKINIT
#define DNS_RDATA_INITIALIZED(rdata) \
(!ISC_LINK_LINKED((rdata), link))
#else
#define DNS_RDATA_INITIALIZED(rdata) true
#endif
#endif
#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
#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, 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, 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, dns_name_t *origin, unsigned int 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, 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.
*
*/
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
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(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, 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
#endif /* DNS_RDATA_H */
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