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diff --git a/contrib/bind9/doc/draft/draft-ietf-dnsext-insensitive-04.txt b/contrib/bind9/doc/draft/draft-ietf-dnsext-insensitive-04.txt deleted file mode 100644 index 4cfd417..0000000 --- a/contrib/bind9/doc/draft/draft-ietf-dnsext-insensitive-04.txt +++ /dev/null @@ -1,639 +0,0 @@ - -INTERNET-DRAFT Donald E. Eastlake 3rd -Clarifies STD0013 Motorola Laboratories -Expires December 2004 July 2004 - - - - Domain Name System (DNS) Case Insensitivity Clarification - ------ ---- ------ ----- ---- ------------- ------------- - <draft-ietf-dnsext-insensitive-04.txt> - - Donald E. Eastlake 3rd - - - -Status of This Document - - By submitting this Internet-Draft, I certify that any applicable - patent or other IPR claims of which I am aware have been disclosed, - and any of which I become aware will be disclosed, in accordance with - RFC 3668. - - Distribution of this document is unlimited. Comments should be sent - to the DNSEXT working group at namedroppers@ops.ietf.org. - - This document is an Internet-Draft and is in full conformance with - all provisions of Section 10 of RFC 2026. Internet-Drafts are - working documents of the Internet Engineering Task Force (IETF), its - areas, and its working groups. Note that other groups may also - distribute working documents as Internet-Drafts. - - Internet-Drafts are draft documents valid for a maximum of six months - and may be updated, replaced, or obsoleted by other documents at any - time. It is inappropriate to use Internet-Drafts as reference - material or to cite them other than as "work in progress." - - The list of current Internet-Drafts can be accessed at - http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet- - Draft Shadow Directories can be accessed at - http://www.ietf.org/shadow.html. - - - -Abstract - - Domain Name System (DNS) names are "case insensitive". This document - explains exactly what that means and provides a clear specification - of the rules. This clarification should not have any interoperability - consequences. - - - - - - - -D. Eastlake 3rd [Page 1] - - -INTERNET-DRAFT DNS Case Insensitivity - - -Acknowledgements - - The contributions to this document of Rob Austein, Olafur - Gudmundsson, Daniel J. Anderson, Alan Barrett, Marc Blanchet, Dana, - Andreas Gustafsson, Andrew Main, and Scott Seligman are gratefully - acknowledged. - - - -Table of Contents - - Status of This Document....................................1 - Abstract...................................................1 - - Acknowledgements...........................................2 - Table of Contents..........................................2 - - 1. Introduction............................................3 - 2. Case Insensitivity of DNS Labels........................3 - 2.1 Escaping Unusual DNS Label Octets......................3 - 2.2 Example Labels with Escapes............................4 - 3. Name Lookup, Label Types, and CLASS.....................4 - 3.1 Original DNS Label Types...............................5 - 3.2 Extended Label Type Case Insensitivity Considerations..5 - 3.3 CLASS Case Insensitivity Considerations................5 - 4. Case on Input and Output................................6 - 4.1 DNS Output Case Preservation...........................6 - 4.2 DNS Input Case Preservation............................6 - 5. Internationalized Domain Names..........................7 - 6. Security Considerations.................................7 - - Copyright and Disclaimer...................................9 - Normative References.......................................9 - Informative References....................................10 - -02 to -03 Changes........................................10 - -03 to -04 Changes........................................11 - Author's Address..........................................11 - Expiration and File Name..................................11 - - - - - - - - - - - - - - -D. Eastlake 3rd [Page 2] - - -INTERNET-DRAFT DNS Case Insensitivity - - -1. Introduction - - The Domain Name System (DNS) is the global hierarchical replicated - distributed database system for Internet addressing, mail proxy, and - other information. Each node in the DNS tree has a name consisting of - zero or more labels [STD 13][RFC 1591, 2606] that are treated in a - case insensitive fashion. This document clarifies the meaning of - "case insensitive" for the DNS. - - The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", - "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this - document are to be interpreted as described in [RFC 2119]. - - - -2. Case Insensitivity of DNS Labels - - DNS was specified in the era of [ASCII]. DNS names were expected to - look like most host names or Internet email address right halves (the - part after the at-sign, "@") or be numeric as in the in-addr.arpa - part of the DNS name space. For example, - - foo.example.net. - aol.com. - www.gnu.ai.mit.edu. - or 69.2.0.192.in-addr.arpa. - - Case varied alternatives to the above would be DNS names like - - Foo.ExamplE.net. - AOL.COM. - WWW.gnu.AI.mit.EDU. - or 69.2.0.192.in-ADDR.ARPA. - - However, the individual octets of which DNS names consist are not - limited to valid ASCII character codes. They are 8-bit bytes and all - values are allowed. Many applications, however, interpret them as - ASCII characters. - - - -2.1 Escaping Unusual DNS Label Octets - - In Master Files [STD 13] and other human readable and writable ASCII - contexts, an escape is needed for the byte value for period (0x2E, - ".") and all octet values outside of the inclusive range of 0x21 - ("!") to 0x7E ("~"). That is to say, 0x2E and all octet values in - the two inclusive ranges 0x00 to 0x20 and 0x7F to 0xFF. - - One typographic convention for octets that do not correspond to an - - -D. Eastlake 3rd [Page 3] - - -INTERNET-DRAFT DNS Case Insensitivity - - - ASCII printing graphic is to use a back-slash followed by the value - of the octet as an unsigned integer represented by exactly three - decimal digits. - - The same convention can be used for printing ASCII characters so that - they will be treated as a normal label character. This includes the - back-slash character used in this convention itself which can be - expressed as \092 or \\ and the special label separator period (".") - which can be expressed as and \046 or \. respectively. It is - advisable to avoid using a backslash to quote an immediately - following non-printing ASCII character code to avoid implementation - difficulties. - - A back-slash followed by only one or two decimal digits is undefined. - A back-slash followed by four decimal digits produces two octets, the - first octet having the value of the first three digits considered as - a decimal number and the second octet being the character code for - the fourth decimal digit. - - - -2.2 Example Labels with Escapes - - The first example below shows embedded spaces and a period (".") - within a label. The second one show a 5 octet label where the second - octet has all bits zero, the third is a backslash, and the fourth - octet has all bits one. - - Donald\032E\.\032Eastlake\0323rd.example. - and a\000\\\255z.example. - - - -3. Name Lookup, Label Types, and CLASS - - The design decision was made that comparisons on name lookup for DNS - queries should be case insensitive [STD 13]. That is to say, a lookup - string octet with a value in the inclusive range of 0x41 to 0x5A, the - upper case ASCII letters, MUST match the identical value and also - match the corresponding value in the inclusive range 0x61 to 0x7A, - the lower case ASCII letters. And a lookup string octet with a lower - case ASCII letter value MUST similarly match the identical value and - also match the corresponding value in the upper case ASCII letter - range. - - (Historical Note: the terms "upper case" and "lower case" were - invented after movable type. The terms originally referred to the - two font trays for storing, in partitioned areas, the different - physical type elements. Before movable type, the nearest equivalent - terms were "majuscule" and "minuscule".) - - -D. Eastlake 3rd [Page 4] - - -INTERNET-DRAFT DNS Case Insensitivity - - - One way to implement this rule would be, when comparing octets, to - subtract 0x20 from all octets in the inclusive range 0x61 to 0x7A - before the comparison. Such an operation is commonly known as "case - folding" but implementation via case folding is not required. Note - that the DNS case insensitivity does NOT correspond to the case - folding specified in iso-8859-1 or iso-8859-2. For example, the - octets 0xDD (\221) and 0xFD (\253) do NOT match although in other - contexts, where they are interpreted as the upper and lower case - version of "Y" with an acute accent, they might. - - - -3.1 Original DNS Label Types - - DNS labels in wire encoded names have a type associated with them. - The original DNS standard [RFC 1035] had only two types. ASCII - labels, with a length of from zero to 63 octets, and indirect labels - which consist of an offset pointer to a name location elsewhere in - the wire encoding on a DNS message. (The ASCII label of length zero - is reserved for use as the name of the root node of the name tree.) - ASCII labels follow the ASCII case conventions described herein and, - as stated above, can actually contain arbitrary byte values. Indirect - labels are, in effect, replaced by the name to which they point which - is then treated with the case insensitivity rules in this document. - - - -3.2 Extended Label Type Case Insensitivity Considerations - - DNS was extended by [RFC 2671] to have additional label type numbers - available. (The only such type defined so far is the BINARY type [RFC - 2673].) - - The ASCII case insensitivity conventions only apply to ASCII labels, - that is to say, label type 0x0, whether appearing directly or invoked - by indirect labels. - - - -3.3 CLASS Case Insensitivity Considerations - - As described in [STD 13] and [RFC 2929], DNS has an additional axis - for data location called CLASS. The only CLASS in global use at this - time is the "IN" or Internet CLASS. - - The handling of DNS label case is not CLASS dependent. - - - - - - -D. Eastlake 3rd [Page 5] - - -INTERNET-DRAFT DNS Case Insensitivity - - -4. Case on Input and Output - - While ASCII label comparisons are case insensitive, [STD 13] says - case MUST be preserved on output, and preserved when convenient on - input. However, this means less than it would appear since the - preservation of case on output is NOT required when output is - optimized by the use of indirect labels, as explained below. - - - -4.1 DNS Output Case Preservation - - [STD 13] views the DNS namespace as a node tree. ASCII output is as - if a name was marshaled by taking the label on the node whose name is - to be output, converting it to a typographically encoded ASCII - string, walking up the tree outputting each label encountered, and - preceding all labels but the first with a period ("."). Wire output - follows the same sequence but each label is wire encoded and no - periods inserted. No "case conversion" or "case folding" is done - during such output operations, thus "preserving" case. However, to - optimize output, indirect labels may be used to point to names - elsewhere in the DNS answer. In determining whether the name to be - pointed to, for example the QNAME, is the "same" as the remainder of - the name being optimized, the case insensitive comparison specified - above is done. Thus such optimization MAY easily destroy the output - preservation of case. This type of optimization is commonly called - "name compression". - - - -4.2 DNS Input Case Preservation - - Originally, DNS input came from an ASCII Master File as defined in - [STD 13] or a zone transfer. DNS Dynamic update and incremental zone - transfers [RFC 1995] have been added as a source of DNS data [RFC - 2136, 3007]. When a node in the DNS name tree is created by any of - such inputs, no case conversion is done. Thus the case of ASCII - labels is preserved if they are for nodes being created. However, - when a name label is input for a node that already exist in DNS data - being held, the situation is more complex. Implementations may retain - the case first input for such a label or allow new input to override - the old case or even maintain separate copies preserving the input - case. - - For example, if data with owner name "foo.bar.example" is input and - then later data with owner name "xyz.BAR.example" is input, the name - of the label on the "bar.example" node, i.e. "bar", might or might - not be changed to "BAR" or the actual input case could be preserved. - Thus later retrieval of data stored under "xyz.bar.example" in this - case can easily return data with "xyz.BAR.example". The same - - -D. Eastlake 3rd [Page 6] - - -INTERNET-DRAFT DNS Case Insensitivity - - - considerations apply when inputting multiple data records with owner - names differing only in case. For example, if an "A" record is stored - as the first resourced record under owner name "xyz.BAR.example" and - then a second "A" record is stored under "XYZ.BAR.example", the - second MAY be stored with the first (lower case initial label) name - or the second MAY override the first so that only an upper case - initial label is retained or both capitalizations MAY be kept. - - Note that the order of insertion into a server database of the DNS - name tree nodes that appear in a Master File is not defined so that - the results of inconsistent capitalization in a Master File are - unpredictable output capitalization. - - - -5. Internationalized Domain Names - - A scheme has been adopted for "internationalized domain names" and - "internationalized labels" as described in [RFC 3490, 3454, 3491, and - 3492]. It makes most of [UNICODE] available through a separate - application level transformation from internationalized domain name - to DNS domain name and from DNS domain name to internationalized - domain name. Any case insensitivity that internationalized domain - names and labels have varies depending on the script and is handled - entirely as part of the transformation described in [RFC 3454] and - [RFC 3491] which should be seen for further details. This is not a - part of the DNS as standardized in STD 13. - - - -6. Security Considerations - - The equivalence of certain DNS label types with case differences, as - clarified in this document, can lead to security problems. For - example, a user could be confused by believing two domain names - differing only in case were actually different names. - - Furthermore, a domain name may be used in contexts other than the - DNS. It could be used as a case sensitive index into some data base - system. Or it could be interpreted as binary data by some integrity - or authentication code system. These problems can usually be handled - by using a standardized or "canonical" form of the DNS ASCII type - labels, that is, always mapping the ASCII letter value octets in - ASCII labels to some specific pre-chosen case, either upper case or - lower case. An example of a canonical form for domain names (and also - a canonical ordering for them) appears in Section 8 of [RFC 2535]. - See also [RFC 3597]. - - Finally, a non-DNS name may be stored into DNS with the false - expectation that case will always be preserved. For example, although - - -D. Eastlake 3rd [Page 7] - - -INTERNET-DRAFT DNS Case Insensitivity - - - this would be quite rare, on a system with case sensitive email - address local parts, an attempt to store two "RP" records that - differed only in case would probably produce unexpected results that - might have security implications. That is because the entire email - address, including the possibly case sensitive local or left hand - part, is encoded into a DNS name in a readable fashion where the case - of some letters might be changed on output as described above. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -D. Eastlake 3rd [Page 8] - - -INTERNET-DRAFT DNS Case Insensitivity - - -Copyright and Disclaimer - - Copyright (C) The Internet Society 2004. This document is subject to - the rights, licenses and restrictions contained in BCP 78, and except - as set forth therein, the authors retain all their rights. - - This document and the information contained herein are provided on an - "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS - OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET - ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, - INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE - INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED - WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. - - - -Normative References - - [ASCII] - ANSI, "USA Standard Code for Information Interchange", - X3.4, American National Standards Institute: New York, 1968. - - [RFC 1034, 1035] - See [STD 13]. - - [RFC 1995] - M. Ohta, "Incremental Zone Transfer in DNS", August - 1996. - - [RFC 2119] - S. Bradner, "Key words for use in RFCs to Indicate - Requirement Levels", March 1997. - - [RFC 2136] - P. Vixie, Ed., S. Thomson, Y. Rekhter, J. Bound, - "Dynamic Updates in the Domain Name System (DNS UPDATE)", April 1997. - - [RFC 2535] - D. Eastlake, "Domain Name System Security Extensions", - March 1999. - - [RFC 3007] - B. Wellington, "Secure Domain Name System (DNS) Dynamic - Update", November 2000. - - [RFC 3597] - Andreas Gustafsson, "Handling of Unknown DNS RR Types", - draft-ietf-dnsext-unknown-rrs-05.txt, March 2003. - - [STD 13] - - P. Mockapetris, "Domain names - concepts and facilities", RFC - 1034, November 1987. - - P. Mockapetris, "Domain names - implementation and - specification", RFC 1035, November 1987. - - - - - - -D. Eastlake 3rd [Page 9] - - -INTERNET-DRAFT DNS Case Insensitivity - - -Informative References - - [RFC 1591] - J. Postel, "Domain Name System Structure and - Delegation", March 1994. - - [RFC 2606] - D. Eastlake, A. Panitz, "Reserved Top Level DNS Names", - June 1999. - - [RFC 2929] - D. Eastlake, E. Brunner-Williams, B. Manning, "Domain - Name System (DNS) IANA Considerations", September 2000. - - [RFC 2671] - P. Vixie, "Extension mechanisms for DNS (EDNS0)", August - 1999. - - [RFC 2673] - M. Crawford, "Binary Labels in the Domain Name System", - August 1999. - - [RFC 3092] - D. Eastlake 3rd, C. Manros, E. Raymond, "Etymology of - Foo", 1 April 2001. - - [RFC 3454] - P. Hoffman, M. Blanchet, "Preparation of - Internationalized String ("stringprep")", December 2002. - - [RFC 3490] - P. Faltstrom, P. Hoffman, A. Costello, - "Internationalizing Domain Names in Applications (IDNA)", March 2003. - - [RFC 3491] - P. Hoffman, M. Blanchet, "Nameprep: A Stringprep Profile - for Internationalized Domain Names (IDN)", March 2003. - - [RFC 3492] - A. Costello, "Punycode: A Bootstring encoding of Unicode - for Internationalized Domain Names in Applications (IDNA)", March - 2003. - - [UNICODE] - The Unicode Consortium, "The Unicode Standard", - <http://www.unicode.org/unicode/standard/standard.html>. - - - --02 to -03 Changes - - The following changes were made between draft version -02 and -03: - - 1. Add internationalized domain name section and references. - - 2. Change to indicate that later input of a label for an existing DNS - name tree node may or may not be normalized to the earlier input or - override it or both may be preserved. - - 3. Numerous minor wording changes. - - - -D. Eastlake 3rd [Page 10] - - -INTERNET-DRAFT DNS Case Insensitivity - - --03 to -04 Changes - - The following changes were made between draft version -03 and -04: - - 1. Change to conform to the new IPR, Copyright, etc., notice - requirements. - - 2. Change in some section headers for clarity. - - 3. Drop section on wildcards. - - 4. Add emphasis on loss of case preservation due to name compression. - - 5. Add references to RFCs 1995 and 3092. - - - -Author's Address - - Donald E. Eastlake 3rd - Motorola Laboratories - 155 Beaver Street - Milford, MA 01757 USA - - Telephone: +1 508-786-7554 (w) - +1 508-634-2066 (h) - EMail: Donald.Eastlake@motorola.com - - - -Expiration and File Name - - This draft expires December 2004. - - Its file name is draft-ietf-dnsext-insensitive-04.txt. - - - - - - - - - - - - - - - - - -D. Eastlake 3rd [Page 11] - - |
