Network Working Group P. Hoffman Internet-Draft VPN Consortium Expires: May 31, 2005 November 30, 2004 The gopher URI Scheme draft-hoffman-gopher-uri-02.txt Status of this Memo This document is an Internet-Draft and is subject to all provisions of section 3 of RFC 3667. By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she become aware will be disclosed, in accordance with RFC 3668. 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. This Internet-Draft will expire on May 31, 2005. Copyright Notice Copyright (C) The Internet Society (2004). Abstract This document specifies the gopher1 Uniform Resource Identifier (URI) scheme that was originally specified in RFC 1738. The purpose of this document is to allow RFC 1738 to be moved to historic while keeping the information about the scheme on standards track. 1. Introduction URIs were previously defined in RFC 2396 [RFC2396], which was updated Hoffman Expires May 31, 2005 [Page 1] Internet-Draft The gopher URI Scheme November 2004 by draft-fielding-uri-rfc2396bis [2396bis]. Those documents also specify how to define schemes for URIs. The first definition for many URI schemes appeared in RFC 1738 [RFC1738]. Because that document has been moved to Historic status, this document copies the gopher URI scheme from it to allow that material to remain on standards track. 2. Scheme Definition The gopher URL scheme is used to designate Internet resources accessible using the Gopher protocol. The base Gopher protocol is described in RFC 1436 [RFC1436] and supports items and collections of items (directories). The Gopher+ protocol is a set of upward compatible extensions to the base Gopher protocol and is described in [Gopher+]. Gopher+ supports associating arbitrary sets of attributes and alternate data representations with Gopher items. Gopher URLs accommodate both Gopher and Gopher+ items and item attributes. Historical note: The Gopher protocol was widely implemented in the early 1990s, but few Gopher servers are in use today. 2.1 Gopher URL syntax A Gopher URL takes the form: gopher://:/ where is one of: %09 %09%09 If : is omitted, the port defaults to 70. is a single-character field to denote the Gopher type of the resource to which the URL refers. The entire may also be empty, in which case the delimiting "/" is also optional and the defaults to "1". is the Gopher selector string. In the Gopher protocol, Gopher selector strings are a sequence of octets which may contain any octets except 09 hexadecimal (US-ASCII HT or tab) 0A hexadecimal (US-ASCII character LF), and 0D (US-ASCII character CR). Gopher clients specify which item to retrieve by sending the Gopher Hoffman Expires May 31, 2005 [Page 2] Internet-Draft The gopher URI Scheme November 2004 selector string to a Gopher server. Within the , no characters are reserved. Note that some Gopher strings begin with a copy of the character, in which case that character will occur twice consecutively. The Gopher selector string may be an empty string; this is how Gopher clients refer to the top-level directory on a Gopher server. 2.2 Specifying URLs for Gopher Search Engines If the URL refers to a search to be submitted to a Gopher search engine, the selector is followed by an encoded tab (%09) and the search string. To submit a search to a Gopher search engine, the Gopher client sends the string (after decoding), a tab, and the search string to the Gopher server. 2.3 URL syntax for Gopher+ items Historical note: Gopher+ was uncommon even when Gopher was popular. URLs for Gopher+ items have a second encoded tab (%09) and a Gopher+ string. Note that in this case, the %09 string must be supplied, although the element may be the empty string. The is used to represent information required for retrieval of the Gopher+ item. Gopher+ items may have alternate views, arbitrary sets of attributes, and may have electronic forms associated with them. To retrieve the data associated with a Gopher+ URL, a client will connect to the server and send the Gopher selector, followed by a tab and the search string (which may be empty), followed by a tab and the Gopher+ commands. 2.4 Default Gopher+ data representation When a Gopher server returns a directory listing to a client, the Gopher+ items are tagged with either a "+" (denoting Gopher+ items) or a "?" (denoting Gopher+ items which have a +ASK form associated with them). A Gopher URL with a Gopher+ string consisting of only a "+" refers to the default view (data representation) of the item while a Gopher+ string containing only a "?" refer to an item with a Gopher electronic form associated with it. Hoffman Expires May 31, 2005 [Page 3] Internet-Draft The gopher URI Scheme November 2004 2.5 Gopher+ items with electronic forms Gopher+ items which have a +ASK associated with them (i.e. Gopher+ items tagged with a "?") require the client to fetch the item's +ASK attribute to get the form definition, and then ask the user to fill out the form and return the user's responses along with the selector string to retrieve the item. Gopher+ clients know how to do this but depend on the "?" tag in the Gopher+ item description to know when to handle this case. The "?" is used in the Gopher+ string to be consistent with Gopher+ protocol's use of this symbol. 2.6 Gopher+ item attribute collections To refer to the Gopher+ attributes of an item, the Gopher URL's Gopher+ string consists of "!" or "$". "!" refers to the all of a Gopher+ item's attributes. "$" refers to all the item attributes for all items in a Gopher directory. 2.7 Referring to specific Gopher+ attributes To refer to specific attributes, the URL's gopher+_string is "!" or "$". For example, to refer to the attribute containing the abstract of an item, the gopher+_string would be "!+ABSTRACT". To refer to several attributes, the gopher+_string consists of the attribute names separated by coded spaces. For example, "!+ABSTRACT%20+SMELL" refers to the +ABSTRACT and +SMELL attributes of an item. 2.8 URL syntax for Gopher+ alternate views Gopher+ allows for optional alternate data representations (alternate views) of items. To retrieve a Gopher+ alternate view, a Gopher+ client sends the appropriate view and language identifier (found in the item's +VIEW attribute). To refer to a specific Gopher+ alternate view, the URL's Gopher+ string would be in the form: +%20 For example, a Gopher+ string of "+application/postscript%20Es_ES" refers to the Spanish language postscript alternate view of a Gopher+ item. 2.9 URL syntax for Gopher+ electronic forms The gopher+_string for a URL that refers to an item referenced by a Gopher+ electronic form (an ASK block) filled out with specific Hoffman Expires May 31, 2005 [Page 4] Internet-Draft The gopher URI Scheme November 2004 values is a coded version of what the client sends to the server. The gopher+_string is of the form: +%091%0D%0A+-1%0D%0A%0D%0A %0D%0A.%0D%0A To retrieve this item, the Gopher client sends the following text to the Gopher server. +1 +-1 . 3. Security Considerations There are many security considerations for URI schemes discussed in [2396bis]. The gopher protocol uses passwords in the clear for authentication, and offers no privacy, both of which are considered extremely unsafe in current practice. 4 Informative References [RFC1738] Berners-Lee, T., Masinter, L. and M. McCahill, "Uniform Resource Locators (URL)", RFC 1738, December 1994. [RFC2396] Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform Resource Identifiers (URI): Generic Syntax", RFC 2396, August 1998. [2396bis] Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform Resource Identifiers (URI): Generic Syntax", work in progress, draft-fielding-uri-rfc2396bis-nn.txt. [RFC1436] Anklesaria, F., McCahill, M., Lindner, P., Johnson, D., Torrey, D. and B. Alberti, "The Internet Gopher Protocol (a distributed document search and retrieval protocol)", RFC 1436, March 1993. Hoffman Expires May 31, 2005 [Page 5] Internet-Draft The gopher URI Scheme November 2004 Author's Address Paul Hoffman VPN Consortium 127 Segre Place Santa Cruz, CA 95060 US EMail: paul.hoffman@vpnc.org Hoffman Expires May 31, 2005 [Page 6] Internet-Draft The gopher URI Scheme November 2004 Intellectual Property Statement The IETF takes no position regarding the validity or scope of any Intellectual Property Rights 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; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. 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Disclaimer of Validity 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. Copyright Statement 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. Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Hoffman Expires May 31, 2005 [Page 7]