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diff --git a/imap/docs/rfc/rfc3516.txt b/imap/docs/rfc/rfc3516.txt deleted file mode 100644 index 4d021975..00000000 --- a/imap/docs/rfc/rfc3516.txt +++ /dev/null @@ -1,451 +0,0 @@ - - - - - - -Network Working Group L. Nerenberg -Request for Comments: 3516 Orthanc Systems -Category: Standards Track April 2003 - - - IMAP4 Binary Content Extension - -Status of this Memo - - This document specifies an Internet standards track protocol for the - Internet community, and requests discussion and suggestions for - improvements. Please refer to the current edition of the "Internet - Official Protocol Standards" (STD 1) for the standardization state - and status of this protocol. Distribution of this memo is unlimited. - -Copyright Notice - - Copyright (C) The Internet Society (2003). All Rights Reserved. - -Abstract - - This memo defines the Binary extension to the Internet Message Access - Protocol (IMAP4). It provides a mechanism for IMAP4 clients and - servers to exchange message body data without using a MIME content- - transfer-encoding. - -1. Conventions Used in this Document - - The key words "MUST", "MUST NOT", "SHOULD", "SHOULD NOT", and "MAY" - in this document are to be interpreted as described in [KEYWORD]. - - The abbreviation "CTE" means content-transfer-encoding. - -2. Introduction - - The MIME extensions to Internet messaging allow for the transmission - of non-textual (binary) message content [MIME-IMB]. Since the - traditional transports for messaging are not always capable of - passing binary data transparently, MIME provides encoding schemes - that allow binary content to be transmitted over transports that are - not otherwise able to do so. - - The overhead of MIME-encoding this content can be considerable in - some contexts (e.g., slow radio links, streaming multimedia). - Reducing the overhead associated with CTE schemes such as base64 - - - - - - -Nerenberg Standards Track [Page 1] - -RFC 3516 IMAP4 Binary Content Extension April 2003 - - - can give a noticeable reduction in resource consumption. The Binary - extension lets the server perform CTE decoding prior to transmitting - message data to the client. - -3. Content-Transfer-Encoding Considerations - - Every IMAP4 body section has a MIME content-transfer-encoding. - (Those without an explicit Content-Transfer-Encoding header are - implicitly labeled as "7bit" content.) In the terminology of [MIME- - IMB], the CTE specifies both a decoding algorithm and the domain of - the decoded data. In this memo, "decoding" refers to the CTE - decoding step described in [MIME-IMB]. - - Certain CTEs use an identity encoding transformation. For these CTEs - there is no decoding required, however the domain of the underlying - data may not be expressible in the IMAP4 protocol (e.g., MIME - "binary" content containing NUL octets). To accommodate these cases - the Binary extension introduces a new type of literal protocol - element that is fully eight bit transparent. - - Thus, server processing of the FETCH BINARY command involves two - logical steps: - - 1) perform any CTE-related decoding - - 2) determine the domain of the decoded data - - Step 2 is necessary to determine which protocol element should be - used to transmit the decoded data. (See FETCH Response Extensions - for further details.) - -4. Framework for the IMAP4 Binary Extension - - This memo defines the following extensions to [IMAP4rev1]. - -4.1. CAPABILITY Identification - - IMAP4 servers that support this extension MUST include "BINARY" in - the response list to the CAPABILITY command. - -4.2. FETCH Command Extensions - - This extension defines three new FETCH command data items. - - BINARY<section-binary>[<partial>] - - Requests that the specified section be transmitted after - performing CTE-related decoding. - - - -Nerenberg Standards Track [Page 2] - -RFC 3516 IMAP4 Binary Content Extension April 2003 - - - The <partial> argument, if present, requests that a subset of - the data be returned. The semantics of a partial FETCH BINARY - command are the same as for a partial FETCH BODY command, with - the exception that the <partial> arguments refer to the DECODED - section data. - - BINARY.PEEK<section-binary>[<partial>] - - An alternate form of FETCH BINARY that does not implicitly set - the \Seen flag. - - BINARY.SIZE<section-binary> - - Requests the decoded size of the section (i.e., the size to - expect in response to the corresponding FETCH BINARY request). - - Note: client authors are cautioned that this might be an - expensive operation for some server implementations. - Needlessly issuing this request could result in degraded - performance due to servers having to calculate the value every - time the request is issued. - -4.3. FETCH Response Extensions - - This extension defines two new FETCH response data items. - - BINARY<section-binary>[<<number>>] - - An <nstring> or <literal8> expressing the content of the - specified section after removing any CTE-related encoding. If - <number> is present it refers to the offset within the DECODED - section data. - - If the domain of the decoded data is "8bit" and the data does - not contain the NUL octet, the server SHOULD return the data in - a <string> instead of a <literal8>; this allows the client to - determine if the "8bit" data contains the NUL octet without - having to explicitly scan the data stream for for NULs. - - If the server does not know how to decode the section's CTE, it - MUST fail the request and issue a "NO" response that contains - the "UNKNOWN-CTE" extended response code. - - - - - - - - - -Nerenberg Standards Track [Page 3] - -RFC 3516 IMAP4 Binary Content Extension April 2003 - - - BINARY.SIZE<section-binary> - - The size of the section after removing any CTE-related - encoding. The value returned MUST match the size of the - <nstring> or <literal8> that will be returned by the - corresponding FETCH BINARY request. - - If the server does not know how to decode the section's CTE, it - MUST fail the request and issue a "NO" response that contains - the "UNKNOWN-CTE" extended response code. - -4.4. APPEND Command Extensions - - The APPEND command is extended to allow the client to append data - containing NULs by using the <literal8> syntax. The server MAY - modify the CTE of the appended data, however any such transformation - MUST NOT result in a loss of data. - - If the destination mailbox does not support the storage of binary - content, the server MUST fail the request and issue a "NO" response - that contains the "UNKNOWN-CTE" extended response code. - -5. MIME Encoded Headers - - [MIME-MHE] defines an encoding that allows for non-US-ASCII text in - message headers. This encoding is not the same as the content- - transfer-encoding applied to message bodies, and the decoding - transformations described in this memo do not apply to [MIME-MHE] - encoded header text. A server MUST NOT perform any conversion of - [MIME-MHE] encoded header text in response to any binary FETCH or - APPEND request. - -6. Implementation Considerations - - Messaging clients and servers have been notoriously lax in their - adherence to the Internet CRLF convention for terminating lines of - textual data in Internet protocols. When sending data using the - Binary extension, servers MUST ensure that textual line-oriented - sections are always transmitted using the IMAP4 CRLF line termination - syntax, regardless of the underlying storage representation of the - data on the server. - - A server may choose to store message body binary content in a non- - encoded format. Regardless of the internal storage representation - used, the server MUST issue BODYSTRUCTURE responses that describe the - message as though the binary-encoded sections are encoded in a CTE - - - - - -Nerenberg Standards Track [Page 4] - -RFC 3516 IMAP4 Binary Content Extension April 2003 - - - acceptable to the IMAP4 base specification. Furthermore, the results - of a FETCH BODY MUST return the message body content in the format - described by the corresponding FETCH BODYSTRUCTURE response. - - While the server is allowed to modify the CTE of APPENDed <literal8> - data, this should only be done when it is absolutely necessary. - Gratuitous encoding changes will render useless most cryptographic - operations that have been performed on the message. - - This extension provides an optimization that is useful in certain - specific situations. It does not absolve clients from providing - basic functionality (content transfer decoding) that should be - available in all messaging clients. Clients supporting this - extension SHOULD be prepared to perform their own CTE decoding - operations. - -7. Formal Protocol Syntax - - The following syntax specification uses the augmented Backus-Naur - Form (ABNF) notation as used in [ABNF], and incorporates by reference - the Core Rules defined in that document. - - This syntax augments the grammar specified in [IMAP4rev1]. - - append =/ "APPEND" SP mailbox [SP flag-list] - [SP date-time] SP literal8 - - fetch-att =/ "BINARY" [".PEEK"] section-binary [partial] - / "BINARY.SIZE" section-binary - - literal8 = "~{" number "}" CRLF *OCTET - ; <number> represents the number of OCTETs - ; in the response string. - - msg-att-static =/ "BINARY" section-binary SP (nstring / literal8) - / "BINARY.SIZE" section-binary SP number - - partial = "<" number "." nz-number ">" - - resp-text-code =/ "UNKNOWN-CTE" - - section-binary = "[" [section-part] "]" - - - - - - - - - -Nerenberg Standards Track [Page 5] - -RFC 3516 IMAP4 Binary Content Extension April 2003 - - -8. Normative References - - [ABNF] Crocker, D., Editor, and P. Overell, "Augmented BNF for - Syntax Specifications: ABNF", RFC 2234, November 1997. - - [IMAP4rev1] Crispin, M., "Internet Message Access Protocol Version - 4rev1", RFC 3501, March 2003. - - [KEYWORD] Bradner, S., "Key words for use in RFCs to Indicate - Requirement Levels", BCP 14, RFC 2119, March 1997. - - [MIME-IMB] Freed, N. and N. Borenstein, "Multipurpose Internet Mail - Extensions (MIME) Part One: Format of Internet Message - Bodies", RFC 2045, November 1996. - - [MIME-MHE] Moore, K., "MIME (Multipurpose Internet Mail Extensions) - Part Three: Message Header Extensions for Non-ASCII - Text", RFC 2047, November 1996. - -9. Security Considerations - - There are no known additional security issues with this extension - beyond those described in the base protocol described in [IMAP4rev1]. - -10. Intellectual Property - - The IETF takes no position regarding the validity or scope of any - intellectual property or other rights that might be claimed to - pertain to the implementation or use of the technology described in - this document or the extent to which any license under such rights - might or might not be available; neither does it represent that it - has made any effort to identify any such rights. Information on the - IETF's procedures with respect to rights in standards-track and - standards-related documentation can be found in BCP-11. Copies of - claims of rights made available for publication and any assurances of - licenses to be made available, or the result of an attempt made to - obtain a general license or permission for the use of such - proprietary rights by implementors or users of this specification can - be obtained from the IETF Secretariat. - - The IETF invites any interested party to bring to its attention any - copyrights, patents or patent applications, or other proprietary - rights which may cover technology that may be required to practice - this standard. Please address the information to the IETF Executive - Director. - - - - - - -Nerenberg Standards Track [Page 6] - -RFC 3516 IMAP4 Binary Content Extension April 2003 - - -11. Author's Address - - Lyndon Nerenberg - Orthanc Systems - 1606 - 10770 Winterburn Road - Edmonton, Alberta - Canada T5S 1T6 - - EMail: lyndon@orthanc.ab.ca - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Nerenberg Standards Track [Page 7] - -RFC 3516 IMAP4 Binary Content Extension April 2003 - - -12. Full Copyright Statement - - Copyright (C) The Internet Society (2003). All Rights Reserved. - - This document and translations of it may be copied and furnished to - others, and derivative works that comment on or otherwise explain it - or assist in its implementation may be prepared, copied, published - and distributed, in whole or in part, without restriction of any - kind, provided that the above copyright notice and this paragraph are - included on all such copies and derivative works. However, this - document itself may not be modified in any way, such as by removing - the copyright notice or references to the Internet Society or other - Internet organizations, except as needed for the purpose of - developing Internet standards in which case the procedures for - copyrights defined in the Internet Standards process must be - followed, or as required to translate it into languages other than - English. - - The limited permissions granted above are perpetual and will not be - revoked by the Internet Society or its successors or assigns. - - This document and the information contained herein is provided on an - "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING - TASK FORCE DISCLAIMS 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. - -Acknowledgement - - Funding for the RFC Editor function is currently provided by the - Internet Society. - - - - - - - - - - - - - - - - - - - -Nerenberg Standards Track [Page 8] - |