INTERNET-DRAFT                                            M. Yevstifeyev
Intended Status: Informational                             July 15, 2011
Updates: RFC-tbd
Expires: January 16, 2012

                     Internalization of 'ftp' URIs
                      draft-yevstifeyev-ftp-iri-00

Abstract

   This document discusses internalization of 'ftp' Uniform Resource
   Identifiers (URIs), which are used to reference resources accessible
   via File Transfer Protocol (FTP).  It updates RFC-tbd.

   [NOTE TO RFC EDITOR: RFC-tbd refers to the [FTP-URI].  Please replace
   "tbd" when [FTP-URI] becomes an RFC with its number.]

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Copyright and License Notice

   Copyright (c) 2011 IETF Trust and the persons identified as the
   document authors. All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
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   carefully, as they describe your rights and restrictions with respect



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   to this document. Code Components extracted from this document must
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Table of Contents

   1. Introduction  . . . . . . . . . . . . . . . . . . . . . . . . .  2
     1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . .  2
   2. Internalized 'ftp' Resource Identifiers (RIs) . . . . . . . . .  3
     2.1. 'ftp' IRIs  . . . . . . . . . . . . . . . . . . . . . . . .  3
     2.2. UCS Characters in 'ftp' URIs  . . . . . . . . . . . . . . .  4
   3. Handling Internalized 'ftp' RIs . . . . . . . . . . . . . . . .  4
     3.1. Internalized <host> Part in 'ftp' URIs and <ihost> Part
          in 'ftp' IRIs . . . . . . . . . . . . . . . . . . . . . . .  4
     3.2. The <user-pass> Part in 'ftp' URIs and IRIs . . . . . . . .  4
     3.3. The <ftp-path> Part in 'ftp' URIs and <iftp-path> in
          'ftp' IRIs  . . . . . . . . . . . . . . . . . . . . . . . .  5
   4. Internalization of Actual Data Interchange  . . . . . . . . . .  5
   5. Mapping 'ftp' IRIs to 'ftp' URIs  . . . . . . . . . . . . . . .  5
   6. Security Considerations . . . . . . . . . . . . . . . . . . . .  5
   7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . .  5
   8. References  . . . . . . . . . . . . . . . . . . . . . . . . . .  6
     8.1. Normative References  . . . . . . . . . . . . . . . . . . .  6
     8.2. Informative References  . . . . . . . . . . . . . . . . . .  7
   Appendix A.  Acknowledgments . . . . . . . . . . . . . . . . . . .  7
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . .  7

. Introduction

   RFC-tbd [FTP-URI] defined the Uniform Resource Identifier (URI)
   scheme used to refer to the resources accessible via File Transfer
   Protocol (FTP) [RFC0959].  RFC 3986 [RFC3986] allows a limited range
   of characters to be present in URIs (particularly, only characters in
   ASCII range [ASCII]).  RFC 3987 [RFC3987] introduced a new protocol
   element - Internationalized Resource Identifiers (IRIs) - which
   supplements URIs by extending the allowed range of characters to all
   Universal Character Set (UCS) characters.  UCS is defined by
   [ISO.10646] and [UNICODE] simultaneously, and includes the characters
   which are able to represent almost any modern script and language.
   See RFC 3536bis [RFC3536bis] for more information.

   This document discusses the internalization of 'ftp' URIs and,
   correspondingly, defines 'ftp' IRIs.  It updates RFC-tbd [FTP-URI].

1.1. Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",



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   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

   The reader is assumed to be familiar with the terminology of RFC 3987
   [RFC3987], RFC 5890 [RFC5890], RFC 3536bis [RFC3536bis] and RFC-tbd
   [FTP-URI].

   In this document Resource Identifier (RI) refers to either URI or
   IRI.

. Internalized 'ftp' Resource Identifiers (RIs)

   The internalized 'ftp' Resource Identifier is meant to be a 'ftp' IRI
   and 'ftp' URI with UCS characters.  The subsequent sections discusses
   how to use UCS with 'ftp' RIs.

2.1. 'ftp' IRIs

   As mentioned before, IRIs provide a way to include UCS characters in
   the resource identifier preserving the functions of URI.  Unlike
   URIs, which also may contain UCS characters, which occur percent-
   encoded, though (see Section 2.2), IRIs represent UCS characters
   directly, by first encoding them using UTF-8 [RFC3629].  This makes
   use of IRIs by humans much easier.  This section defines the valid
   syntax of 'ftp' IRIs.

   The 'ftp' IRI takes the form of <ftp-iri> rule below, defined using
   ABNF [RFC5234]:

     ftp-iri        = "ftp:" ftp-ihier-part
     ftp-ihier-part = "//" [ user-pass "@" ] ihost-port [ iftp-path ]

     user-pass      = <as defined in RFC-tbd [FTP-URI]>
                    ; not internalized - see below

     ihost-port     = ihost [ ":" port ]

     iftp-path      = [ icwd-part ] "/" ilast-segment [ typecode-part ]
     icwd-part      = *( "/" icwd )
     icwd           = isegment-nsc
     last-segment   = isegment-nsc
     isegment-nsc   = *ipchar-nsc
     ipchar-nsc     = iunreserved / pct-encoded / sub-delims-nsc / ":"
                    / "@"
     sub-delims-nsc = "!" / "$" / "&" / "'" / "(" / ")" / "*" / "+" /
                    / "," / "="
     typecode-part  = <as defined in RFC-tbd [FTP-URI]>




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   where the rules <ihost> and <iunreserved> are defined in RFC 3987
   [RFC3987], <pct-encoded> and <port> - in RFC 3986 [RFC3986], and
   <user-pass> and <typecode-part> - in RFC-tbd [FTP-URI].

2.2. UCS Characters in 'ftp' URIs

   Valid 'ftp' URIs MAY contain UCS characters in their <host> and <ftp-
   path> parts, as mentioned in Section 3.3 of RFC-tbd and Section 2.5
   of RFC 3986.  In order to use such character in one of these parts,
   it SHALL first be encoded with UTF-8 [RFC3629].  The resulting
   sequence of octets SHALL be examined to conclude whether some octets
   match corresponding ASCII characters.  If one does, and such
   character is allowed in a particular part of 'ftp' URI, it SHALL be
   presented in the URI directly; otherwise, the octet SHALL be
   represented percent-encoded.

. Handling Internalized 'ftp' RIs

   This section defines the rules which concern handling internalized
   'ftp' RIs.  The valid syntax for 'ftp' IRIs is defined above; how to
   include UCS characters is also discussed above.

3.1. Internalized <host> Part in 'ftp' URIs and <ihost> Part in 'ftp'
   IRIs

   The <host> part in 'ftp' URIs and <ihost> part in 'ftp' IRIs may
   contain internalized strings, with UCS characters being percent-
   encoded and displayed directly, respectively.

   As Domain Name System (DNS) does not allow the UTF-8 encoded data in
   its interchange, limiting the allowed characters range to ASCII
   [ASCII], the usual procedure of UTF-8 transformation is insufficient
   here.  Hence, in order to make up the valid domain name for lookup
   and further processing the following step SHALL be applied:

   (1) represent the domain name which contains UCS characters as an
       octets stream in UTF-8 [RFC3629];

   (2) apply the algorithm for IDN lookup defined in Section 5 of RFC
       5891 [RFC5891].

   The received A-label SHALL also be used with FTP HOST command [I-D
   ietf-ftpext2-hosts], sent when establishing FTP connection per
   Section 3.2.1 of RFC-tbd [FTP-URI].

3.2. The <user-pass> Part in 'ftp' URIs and IRIs

   The <user-pass> part of 'ftp' IRIs is not internalized.  FTP does not



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   allow the UCS characters to be present in user names or passwords,
   and does not allow to enable such feature.  Correspondingly, when
   processing 'ftp' RIs, either URIs or IRIs, the <user-pass> may
   contain characters only allowed by RFC-tbd [FTP-URI].

3.3. The <ftp-path> Part in 'ftp' URIs and <iftp-path> in 'ftp' IRIs

   The <ftp-path> and <iftp-path> parts allow to include UCS characters
   in FTP pathnames present in URIs and IRIs, respectively.

   In order to successfully process an internalized FTP pathname, a
   client prior to its processing SHALL examine the server's response to
   the FEAT command [RFC2389], issued upon authentication per Section
   3.2.2 of RFC-tbd [FTP-URI].  If one of the lines of the response is
   "UTF8", the server supports UTF-8 encoded pathnames [RFC2640].
   Otherwise, if there is no such line, or the server does not support
   the FEAT mechanism, the contrary SHALL be assumed.

   Should it be determined that server supports UTF-8 encoded pathnames,
   the internalized pathname parts SHALL be encoded with UTF-8 [RFC3629]
   and then transmitted as an arguments to the corresponding FTP
   commands as UTF-8 octets stream.

. Internalization of Actual Data Interchange

   'ftp' RIs may refer to the file which contains the internalized data.
    When transmitting such file over data connection, it should be in
   Net-Unicode format [RFC5198].  In order to indicate this, the
   <typecode> equal to "u" [I-D ietf-ftpext2-typeu] SHALL be set in the
   'ftp' RI.

. Mapping 'ftp' IRIs to 'ftp' URIs

   'ftp' IRIs are subject to the rules of Section 3.1 of RFC 3987 with
   respect to their mapping to 'ftp' URIs.

. Security Considerations

   Security considerations for usage of IRIs are discussed in Section 8
   of RFC 3987 [RFC3987]; for usage of Internalized Domain Names - in
   RFC 5890 [RFC5890].  This document adds nothing to those security
   considerations.

. IANA Considerations

   IANA is asked to list this document as an additional reference to
   'ftp' URI scheme registration.




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. References

8.1. Normative References

   [ASCII]    American National Standards Institute (ANSI), "Coded
              Character Set -- 7-bit American Standard Code for
              Information Interchange", ANSI X3.4-1986, December 1986.

   [FTP-URI]  Yevstifeyev, M., "The 'ftp' URI Scheme", Work in Progress
              (draft-yevstifeyev-ftp-uri-scheme), July 2011.

   [I-D ietf-ftpext2-typeu]
              Klensin, J., "FTP TYPE Extension for Internationalized
              Text", Work in Progress (draft-ietf-ftpext2-typeu), June
              2011.

   [ISO.10646]
              International Organization for Standardization (ISO),
              "Information technology -- Universal Coded Character Set
              (UCS)", ISO/IEC 10646:2011, March 2011.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC2640]  Curtin, B., "Internationalization of the File Transfer
              Protocol", RFC 2640, July 1999.

   [RFC3629]  Yergeau, F., "UTF-8, a transformation format of ISO
              10646", STD 63, RFC 3629, November 2003.

   [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
              Resource Identifier (URI): Generic Syntax", STD 66,
              RFC 3986, January 2005.

   [RFC3987]  Duerst, M. and M. Suignard, "Internationalized Resource
              Identifiers (IRIs)", RFC 3987, January 2005.

   [RFC5234]  Crocker, D., Ed., and P. Overell, "Augmented BNF for
              Syntax Specifications: ABNF", STD 68, RFC 5234, January
              2008.

   [RFC5891]  Klensin, J., "Internationalized Domain Names in
              Applications (IDNA): Protocol", RFC 5891, August 2010.

   [UNICODE]  The Unicode Consortium, "The Unicode Standard, Version
              6.0.0", (Mountain View, CA: The Unicode Consortium, 2011.
              ISBN 978-1-936213-01-6), 2011,
              <http://www.unicode.org/versions/Unicode6.0.0/>.



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8.2. Informative References

   [I-D ietf-ftpext2-hosts]
              Hethmon, P., and R. McMurray, "File Transfer Protocol HOST
              Command for Virtual Hosts", Work in Progress (draft-ietf-
              ftpext2-hosts), February 2011.

   [RFC0959]  Postel, J. and J. Reynolds, "File Transfer Protocol", STD
              9, RFC 959, October 1985.

   [RFC2389]  Hethmon, P. and R. Elz, "Feature negotiation mechanism for
              the File Transfer Protocol", RFC 2389, August 1998.

   [RFC5198]  Klensin, J. and M. Padlipsky, "Unicode Format for Network
              Interchange", RFC 5198, March 2008.

   [RFC5890]  Klensin, J., "Internationalized Domain Names for
              Applications (IDNA): Definitions and Document Framework",
              RFC 5890, August 2010.

   [RFC3536bis]
              Hoffman, P., and J. Klensin, "Terminology Used in
              Internationalization in the IETF", Work in Progress
              (draft-ietf-appsawg-rfc3536bis), June 2011.

Appendix A.  Acknowledgments

   I'd like to thank <TBD> for their input to this document.

Authors' Addresses

   Mykyta Yevstifeyev
   8 Kuzovkov St., Apt 25
   Kotovsk
   Ukraine

   EMail: evnikita2@gmail.com














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