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dns
rdata.h
/* * 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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