idnits 2.17.1 draft-ietf-dnsext-unknown-rrs-02.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- ** Looks like you're using RFC 2026 boilerplate. This must be updated to follow RFC 3978/3979, as updated by RFC 4748. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- == No 'Intended status' indicated for this document; assuming Proposed Standard Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- ** The document seems to lack separate sections for Informative/Normative References. All references will be assumed normative when checking for downward references. == There are 1 instance of lines with private range IPv4 addresses in the document. If these are generic example addresses, they should be changed to use any of the ranges defined in RFC 6890 (or successor): 192.0.2.x, 198.51.100.x or 203.0.113.x. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the RFC 3978 Section 5.4 Copyright Line does not match the current year -- The document seems to lack a disclaimer for pre-RFC5378 work, but may have content which was first submitted before 10 November 2008. If you have contacted all the original authors and they are all willing to grant the BCP78 rights to the IETF Trust, then this is fine, and you can ignore this comment. If not, you may need to add the pre-RFC5378 disclaimer. (See the Legal Provisions document at https://trustee.ietf.org/license-info for more information.) -- The document date (November 2001) is 8197 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Missing Reference: 'RFC 2119' is mentioned on line 55, but not defined == Unused Reference: 'RFC1034' is defined on line 218, but no explicit reference was found in the text == Unused Reference: 'RFC1035' is defined on line 221, but no explicit reference was found in the text == Unused Reference: 'RFC2052' is defined on line 227, but no explicit reference was found in the text == Unused Reference: 'RFC2119' is defined on line 230, but no explicit reference was found in the text == Unused Reference: 'RFC2782' is defined on line 239, but no explicit reference was found in the text == Unused Reference: 'RFC2929' is defined on line 242, but no explicit reference was found in the text ** Obsolete normative reference: RFC 2535 (Obsoleted by RFC 4033, RFC 4034, RFC 4035) -- Duplicate reference: RFC2782, mentioned in 'RFC2782', was also mentioned in 'RFC2052'. ** Obsolete normative reference: RFC 2929 (Obsoleted by RFC 5395) Summary: 4 errors (**), 0 flaws (~~), 10 warnings (==), 3 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 INTERNET-DRAFT Andreas Gustafsson 3 draft-ietf-dnsext-unknown-rrs-02.txt ISC 4 November 2001 6 Handling of Unknown DNS RR Types 8 Status of this Memo 10 This document is an Internet-Draft and is in full conformance with 11 all provisions of Section 10 of RFC2026. 13 Internet-Drafts are working documents of the Internet Engineering 14 Task Force (IETF), its areas, and its working groups. Note that 15 other groups may also distribute working documents as Internet- 16 Drafts. 18 Internet-Drafts are draft documents valid for a maximum of six months 19 and may be updated, replaced, or obsoleted by other documents at any 20 time. It is inappropriate to use Internet-Drafts as reference 21 material or to cite them other than as "work in progress." 23 The list of current Internet-Drafts can be accessed at 24 http://www.ietf.org/ietf/1id-abstracts.txt 26 The list of Internet-Draft Shadow Directories can be accessed at 27 http://www.ietf.org/shadow.html. 29 Abstract 31 Extending the Domain Name System with new Resource Record types 32 currently requires changes to name server software. This document 33 specifies the changes necessary to allow future DNS implementations 34 to handle new RR types transparently. 36 1. Introduction 38 The DNS is designed to be extensible to support new services through 39 the introduction of new resource record (RR) types. In practice, 40 deploying a new RR type currently requires changes to the name server 41 software not only at the authoritative DNS server that is providing 42 the new information and the client making use of it, but also at all 43 slave servers for the zone containing it, and in some cases also at 44 caching name servers and forwarders used by the client. 46 Because the deployment of new server software is slow and expensive, 47 the potential of the DNS in supporting new services has never been 48 fully realized. This memo proposes changes to name servers and to 49 procedures for defining new RR types aimed at simplifying the future 50 deployment of new RR types. 52 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 53 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 54 document are to be interpreted as described in [RFC 2119]. 56 2. Definition 58 An "RR of unknown type" is an RR whose RDATA format is not known to 59 the DNS implementation at hand, such that it cannot be converted to a 60 type-specific text format, compressed, or otherwise handled in a 61 type-specific way, and whose type is not an assigned QTYPE or Meta- 62 TYPE in RFC2929 section 3.1 nor within the range reserved in that 63 section for assignment only to QTYPEs and Meta-TYPEs. 65 In the case of a type whose RDATA format is class specific, an RR is 66 considered to be of unknown type when the RDATA format for that 67 combination of type and class is not known. 69 3. Transparency 71 To enable new RR types to be deployed without server changes, name 72 servers and resolvers MUST handle RRs of unknown type transparently. 73 That is, they must treat the RDATA section of such RRs as 74 unstructured binary data, storing and transmitting it without change 75 [RFC1123]. 77 4. Domain Name Compression 79 RRs containing compression pointers in the RDATA part cannot be 80 treated transparently, as the compression pointers are only 81 meaningful within the context of a DNS message. Transparently 82 copying the RDATA into a new DNS message would cause the compression 83 pointers to point at the corresponding location in the new message, 84 which now contains unrelated data. This would cause the compressed 85 name to be corrupted. 87 To avoid such corruption, servers MUST NOT compress domain names 88 embedded in the RDATA of types that are class-specific or not well- 89 known. This requirement was stated in RFC1123 without defining the 90 term "well-known"; it is hereby specified that only the RR types 91 defined in RFC1035 are to be considered "well-known". 93 Receiving servers MUST decompress domain names in RRs of well-known 94 type, and SHOULD also decompress RRs of type RP, AFSDB, RT, SIG, PX, 95 NXT, NAPTR, and SRV (although the current specification of the SRV RR 96 in RFC2782 prohibits compression, RFC2052 mandated it, and some 97 servers following that earlier specification are still in use). 99 Future specifications for new RR types that contain domain names 100 within their RDATA MUST NOT allow the use of name compression for 101 those names, and SHOULD explicitly state that the embedded domain 102 names MUST NOT be compressed. 104 As noted in RFC1123, the owner name of an RR is always eligible for 105 compression. 107 5. Text Representation 109 In the "type" field of a master file line, an unknown RR type is 110 represented by the word "TYPE" immediately followed by the decimal RR 111 type number, with no intervening whitespace. In the "class" field, 112 an unknown class is similarly represented as the word "CLASS" 113 immediately followed by the decimal class number. 115 This convention allows types and classes to be distinguished from 116 each other and from TTL values, allowing the "[] [] 117 " and "[] [] " forms of 118 RFC1035 to both be unambiguously parsed. 120 The RDATA section of an RR of unknown type is represented as a 121 sequence of white space separated words as follows: 123 The special token \# (a backslash immediately 124 followed by a hash sign), which identifies the 125 RDATA as having the generic encoding defined 126 herein rather than a traditional type-specific 127 encoding. 129 An unsigned decimal integer specifying the 130 RDATA length in octets. 132 Zero or more words of hexadecimal data encoding 133 the actual RDATA field, each containing an even 134 number of hexadecimal digits. 136 If the RDATA is of zero length, the text representation contains only 137 the \# token and the single zero representing the length. 139 An implementation MAY also choose to represent some RRs of known type 140 using the above generic representations for the type, class and/or 141 RDATA, which carries the benefit of making the resulting master file 142 portable to servers where these types are unknown. 144 Even though an RR of known type represented in the \# format is 145 effectively treated as an unknown type for the purpose of parsing the 146 RDATA text representation, all further processing by the server MUST 147 treat it as a known type and take into account any applicable type- 148 specific rules regarding compression, canonicalization, etc. 150 The following are examples of RRs represented in this manner, 151 illustrating various combinations of generic and type-specific 152 encodings for the different fields of the master file format: 154 a.example. CLASS32 TYPE731 \# 6 abcd ( 155 ef 01 23 45 ) 156 b.example. HS TYPE62347 \# 0 157 e.example. IN A \# 4 0A000001 158 e.example. CLASS1 TYPE1 10.0.0.2 160 6. Equality Comparison 162 Certain DNS protocols, notably Dynamic Update [RFC2136], require RRs 163 to be compared for equality. Two RRs of the same unknown type are 164 considered equal when their RDATA is bitwise equal. To ensure that 165 the outcome of the comparison is identical whether the RR is known to 166 the server or not, specifications for new RR types MUST NOT specify 167 type-specific comparison rules. 169 This implies that embedded domain names, being included in the 170 overall bitwise comparison, are compared in a case-sensitive manner. 171 As a result, when a new RR type contains one or more embedded domain 172 names, it is possible to have multiple RRs owned by the same name 173 that differ only in the character case of the embedded domain 174 name(s). This is similar to the existing possibility of multiple TXT 175 records differing only in character case, and not expected to cause 176 any problems in practice. 178 7. DNSSEC Canonical Form and Ordering 180 DNSSEC [RFC2535] defines a canonical form and ordering for RRs. In 181 the canonical form, domain names embedded in the RDATA are converted 182 to lower case. 184 To ensure backwards compatibility, this canonical form remains 185 unchanged for any RR types defined in RFC2931 or earlier. That is, 186 the domain names embedded in RRs of type NS, MD, MF, CNAME, SOA, MB, 187 MG, MR, PTR, HINFO, MINFO, MX, HINFO, RP, AFSDB, RT, SIG, PX, NXT, 188 NAPTR, KX, SRV, DNAME, and A6 are converted to lower case. For all 189 other RR types, the canonical form is hereby changed such that no 190 downcasing of embedded domain names takes place. The owner name is 191 still set to lower case. 193 The canonical ordering is as specified in RFC2535 section 8.3, where 194 the octet sequence is the canonical form as revised by this 195 specification. 197 8. Additional Section Processing 199 Unknown RR types cause no additional section processing. Future RR 200 type specifications MAY specify type-specific additional section 201 processing rules, but any such processing MUST be optional as it can 202 only be performed by servers for which the RR type in case is known. 204 9. IANA Considerations 206 The IANA is hereby requested to verify that specifications for new RR 207 types requesting an RR type number comply with this specification. 208 In particular, the IANA MUST NOT assign numbers to new RR types whose 209 specification allows embedded domain names to be compressed. 211 10. Security Considerations 213 This specification is not believed to cause any new security 214 problems, nor to solve any existing ones. 216 References 218 [RFC1034] - Domain Names - Concepts and Facilities, P. Mockapetris, 219 November 1987. 221 [RFC1035] - Domain Names - Implementation and Specifications, P. 222 Mockapetris, November 1987. 224 [RFC1123] - Requirements for Internet Hosts -- Application and 225 Support, R. Braden, Editor, October 1989. 227 [RFC2052] - A DNS RR for specifying the location of services (DNS 228 SRV), A. Gulbrandsen, P. Vixie, October 1996. Obsoleted by RFC2782. 230 [RFC2119] - Bradner, S., "Key words for use in RFCs to Indicate 231 Requirement Levels", BCP 14, RFC 2119, March 1997. 233 [RFC2136] - Dynamic Updates in the Domain Name System (DNS UPDATE). 234 P. Vixie, Ed., S. Thomson, Y. Rekhter, J. Bound, April 1997. 236 [RFC2535] - Domain Name System Security Extensions. D. Eastlake, 237 March 1999. 239 [RFC2782] - A DNS RR for specifying the location of services (DNS 240 SRV). A. Gulbrandsen, P. Vixie, L. Esibov, February 2000. 242 [RFC2929] - Domain Name System (DNS) IANA Considerations. D. 243 Eastlake, E. Brunner-Williams, B. Manning, September 2000. 245 Author's Address 247 Andreas Gustafsson 248 ISC 249 950 Charter Street 250 Redwood City, CA 94063 251 USA 253 Phone: +1 650 779 7004 255 Email: Andreas_Gustafsson@isc.org 257 Full Copyright Statement 259 Copyright (C) The Internet Society (2001). All Rights Reserved. 261 This document and translations of it may be copied and furnished to 262 others, and derivative works that comment on or otherwise explain it 263 or assist in its implmentation may be prepared, copied, published and 264 distributed, in whole or in part, without restriction of any kind, 265 provided that the above copyright notice and this paragraph are 266 included on all such copies and derivative works. However, this 267 document itself may not be modified in any way, such as by removing 268 the copyright notice or references to the Internet Society or other 269 Internet organizations, except as needed for the purpose of 270 developing Internet standards in which case the procedures for 271 copyrights defined in the Internet Standards process must be 272 followed, or as required to translate it into languages other than 273 English. 275 The limited permissions granted above are perpetual and will not be 276 revoked by the Internet Society or its successors or assigns. 278 This document and the information contained herein is provided on an 279 "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING 280 TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING 281 BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION 282 HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF 283 MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE."