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(See the Legal Provisions document at https://trustee.ietf.org/license-info for more information.) -- The document date (July 28, 2008) is 5749 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) -- Possible downref: Non-RFC (?) normative reference: ref. 'ASCII' -- Possible downref: Non-RFC (?) normative reference: ref. 'Unicode51' Summary: 1 error (**), 0 flaws (~~), 1 warning (==), 10 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group J. Klensin 3 Internet-Draft July 28, 2008 4 Updates: 959 (if approved) 5 Intended status: Standards Track 6 Expires: January 29, 2009 8 FTP Extension for Internationalized Text 9 draft-klensin-ftp-typeu-00.txt 11 Status of this Memo 13 By submitting this Internet-Draft, each author represents that any 14 applicable patent or other IPR claims of which he or she is aware 15 have been or will be disclosed, and any of which he or she becomes 16 aware will be disclosed, in accordance with Section 6 of BCP 79. 18 Internet-Drafts are working documents of the Internet Engineering 19 Task Force (IETF), its areas, and its working groups. Note that 20 other groups may also distribute working documents as Internet- 21 Drafts. 23 Internet-Drafts are draft documents valid for a maximum of six months 24 and may be updated, replaced, or obsoleted by other documents at any 25 time. It is inappropriate to use Internet-Drafts as reference 26 material or to cite them other than as "work in progress." 28 The list of current Internet-Drafts can be accessed at 29 http://www.ietf.org/ietf/1id-abstracts.txt. 31 The list of Internet-Draft Shadow Directories can be accessed at 32 http://www.ietf.org/shadow.html. 34 This Internet-Draft will expire on January 29, 2009. 36 Abstract 38 The original FTP protocol supported TYPE values for ASCII and EBCDIC 39 text, plus binary ("IMAGE") transmission. As the Internet becomes 40 more international, there is a growing requirement to be able to 41 transmit textual data, encoded in Unicode, in a way that is 42 independent of the coding and line representation forms of particular 43 operating systems. This memo specifies a new FTP TYPE value for 44 Unicode data. 46 Table of Contents 48 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 49 1.1. Context and Overview . . . . . . . . . . . . . . . . . . . 3 50 1.2. History of Internationalization of FTP . . . . . . . . . . 3 51 1.3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . 3 52 1.4. Discussion List . . . . . . . . . . . . . . . . . . . . . . 3 53 2. Specification . . . . . . . . . . . . . . . . . . . . . . . . . 4 54 2.1. Existing TYPEs . . . . . . . . . . . . . . . . . . . . . . 4 55 2.2. Unicode TYPE . . . . . . . . . . . . . . . . . . . . . . . 4 56 2.3. Data Structure . . . . . . . . . . . . . . . . . . . . . . 5 57 2.4. Feature Negotiation . . . . . . . . . . . . . . . . . . . . 5 58 3. Net-Unicode Format for FTP . . . . . . . . . . . . . . . . . . 5 59 4. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 5 60 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6 61 6. Security Considerations . . . . . . . . . . . . . . . . . . . . 6 62 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6 63 7.1. Normative References . . . . . . . . . . . . . . . . . . . 6 64 7.2. Informative References . . . . . . . . . . . . . . . . . . 7 65 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 7 66 Intellectual Property and Copyright Statements . . . . . . . . . . 8 68 1. Introduction 70 1.1. Context and Overview 72 The original FTP protocol [RFC0959] supported TYPE values for ASCII 73 and EBCDIC text, plus binary ("IMAGE") transmission. The Host 74 Requirements specification [RFC1123] made other changes to FTP, but 75 did not alter the TYPE environment. 77 As the Internet becomes more international, there is a growing 78 requirement to be able to transmit textual data, encoded in Unicode 79 [Unicode51], in a way that is independent of the coding and line 80 representation forms of particular operating systems. This memo 81 specifies a new FTP TYPE value for Unicode data. 83 1.2. History of Internationalization of FTP 85 RFC 2640 [RFC2640] is described as providing internationalization of 86 FTP, but only addresses the use of FTP in internationalized (non- 87 ASCII or extended ASCII [ASCII]) file systems. Its facilities were 88 slightly enhanced in a more general extensions specification 89 [RFC3659], which builds on a more general FTP extension mechanism 90 [RFC2389]. This document addresses the transfer of non-ASCII text 91 files only, building on the TYPE command of the original FTP 92 specification [RFC0959]. 94 1.3. Terminology 96 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 97 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 98 document are to be interpreted as described in [RFC2119]. 100 This document assumes that the reader is familiar with the 101 terminology of RFC 959. Those terms, especially reply, server-FTP 102 process, user-FTP process, server-PI, user-PI, logical byte size, and 103 user, if used here, are used in the same way. It also uses the ABNF 104 of [RFC2389] and [RFC5234] in preference to the BNF of RFC 959. For 105 the convenience of contemporary readers, the terms "client" and 106 "server" are used interchangeably with the historic terms "user-FTP 107 process" and "server-FTP process". The document also assumes the 108 termology and changes in the updates to FTP specified in RFC 1123 and 109 RFC 2389. 111 1.4. Discussion List 113 [[anchor6: RFC Editor: please remove this section before 114 publication.]] 115 Until and unless a WG is created, this proposal will be discussed on 116 the list apps-discuss@ietf.org 118 2. Specification 120 2.1. Existing TYPEs 122 The FTP TYPE command, described in [RFC0959] accepts four possible 123 first argument values, as described below. Note that these 124 descriptions are provided for the reader's convenience; the 125 definitions in RFC 959 remain normative. 127 TYPE A The data are expected to be in, and are transformed by the 128 server if needed to, an ASCII [ASCII] data stream conforming to 129 the "NVT" specification (See RFC 959 [RFC0959] and Appendix B of 130 RFC 5198 [RFC5198] for more information). 132 E The data are expected to be in, and are transformed by the server 133 if needed to, an EBCDIC data stream as specified in RFC 959. 135 I The data are transferred in "image" form, i.e., exactly as they 136 appear in the server. Because it is the only TYPE form in which 137 true binary data can be transferred, TYPE I is often referred to 138 as "binary" or "binary transfer". 140 L The data are transmitted in logical bytes of a size specified in 141 an additional argument. See RFC 959. 143 Any of these four argument variations to TYPE except "TYPE A" (with 144 non-print format) MAY be rejected by the server-FTP process with a 145 504 response code if it does not support that type and the necessary 146 conversions. 148 2.2. Unicode TYPE 150 The client-PI MAY transmit TYPE U to the server-PI as an alternative 151 to other TYPE commands and arguments. If it does, the server MAY 152 return reply-code 504, indicating that the TYPE U feature is not 153 supported (unchanged from RFC 959) or MUST respond to any data 154 retrieval request (e.g., GET) by sending the data in a stream 155 conformant to the Net-Unicode format specified in Section 3. 156 Similarly, if the client-PI sends TYPE U and the server accepts it, 157 the client MUST send any data streams in that format while the option 158 is in effect. No second parameter is used or permitted for TYPE U. 160 2.3. Data Structure 162 The default and only permitted data structure for TYPE U is "file 163 structure". Use of the STRU command SHOULD be avoided. If is used, 164 its argument MUST be "F". 166 2.4. Feature Negotiation 168 RFC 2389 [RFC2389] specifies a feature negotiation mechanism for new 169 extensions to FTP. Since the TYPE command is a required part of the 170 base FTP specification, the client-PI is not required to issue the 171 FEAT command prior to issuing TYPE U. However, it MAY do so and 172 Server-FTP implementations that include TYPE U SHOULD support FEAT as 173 described below. If the FEAT command is transmitted from the 174 client-PI to the server-PI, and this extension and FEAT are 175 supported, the response MUST include a TYPE line that lists all TYPE 176 values supported by the server (including the required ones). For 177 example, if an FTP-server supports all of TYPEs A, E, I, and U, the 178 FEAT response line would contain each of the possible arguments 179 separated by semicolons, e.g., 181 TYPE A;E;I;U 183 This specification does not change either RFC 959 or RFC 2389. In 184 particular, no FEAT response line is required for TYPE unless this, 185 or some other, extension to TYPE is supported by the FTP-server. 187 3. Net-Unicode Format for FTP 189 This section specifies a profile of Net-Unicode [RFC5198] for use 190 with FTP TYPE U. 192 Unicode characters must be transmitted in UTF-8 as specified in 193 [RFC5198]. Because FTP is used in data transmission, the characters 194 and sequences that are discouraged in Section 2 of RFC 5198 are 195 permitted to be transported by FTP. However, line-ending sequences 196 MUST conform to the CRLF convention specified there. Consistent with 197 Paragraph 4 of that Section, strings SHOULD be normalized before 198 transmission if at all possible. 200 The implicit logical byte size for this transmission type is eight 201 bits. 203 4. Acknowledgments 205 This document draws heavily on RFC 959; appreciation is expressed to 206 its authors and to the authors of RFC 2398. The work of Mark P. 207 Peterson and Douglas J. Papenthien on other FTP extensions finally 208 motivated production of this document after a long delay; that 209 contribution is appreciated as well. 211 5. IANA Considerations 213 If the FTP extension registry established by a companion document 214 [FTPExtReg] is defined, an entry for "TYPE U" that refers to this 215 specification should be incorporated in that registry. 217 6. Security Considerations 219 ...??? ... 221 7. References 223 7.1. Normative References 225 [ASCII] American National Standards Institute (formerly United 226 States of America Standards Institute), "USA Code for 227 Information Interchange", ANSI X3.4-1968, 1968. 229 ANSI X3.4-1968 has been replaced by newer versions with 230 slight modifications, but the 1968 version remains 231 definitive for the Internet. 233 [FTPExtReg] 234 Klensin, J., "FTP Extension Registry", July 2008, . 238 [RFC0959] Postel, J. and J. Reynolds, "File Transfer Protocol", 239 STD 9, RFC 959, October 1985. 241 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 242 Requirement Levels", BCP 14, RFC 2119, March 1997. 244 [RFC2389] Hethmon, P. and R. Elz, "Feature negotiation mechanism for 245 the File Transfer Protocol", RFC 2389, August 1998. 247 [RFC5198] Klensin, J. and M. Padlipsky, "Unicode Format for Network 248 Interchange", RFC 5198, March 2008. 250 [RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax 251 Specifications: ABNF", STD 68, RFC 5234, January 2008. 253 [Unicode51] 254 The Unicode Consortium, "The Unicode Standard, Version 255 5.1.0", 2008. 257 defined by: The Unicode Standard, Version 5.0, Boston, MA, 258 Addison-Wesley, 2007, ISBN 0-321-48091-0, as amended by 259 Unicode 5.1.0 260 (http://www.unicode.org/versions/Unicode5.1.0/). 262 7.2. Informative References 264 [RFC1123] Braden, R., "Requirements for Internet Hosts - Application 265 and Support", STD 3, RFC 1123, October 1989. 267 [RFC2640] Curtin, B., "Internationalization of the File Transfer 268 Protocol", RFC 2640, July 1999. 270 [RFC3659] Hethmon, P., "Extensions to FTP", RFC 3659, March 2007. 272 Author's Address 274 John C Klensin 275 1770 Massachusetts Ave, Ste 322 276 Cambridge, MA 02140 277 USA 279 Phone: +1 617 245 1457 280 Email: john+ietf@jck.com 282 Full Copyright Statement 284 Copyright (C) The IETF Trust (2008). 286 This document is subject to the rights, licenses and restrictions 287 contained in BCP 78, and except as set forth therein, the authors 288 retain all their rights. 290 This document and the information contained herein are provided on an 291 "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS 292 OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND 293 THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS 294 OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF 295 THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED 296 WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 298 Intellectual Property 300 The IETF takes no position regarding the validity or scope of any 301 Intellectual Property Rights or other rights that might be claimed to 302 pertain to the implementation or use of the technology described in 303 this document or the extent to which any license under such rights 304 might or might not be available; nor does it represent that it has 305 made any independent effort to identify any such rights. 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