RFC 3368

The 'go' URI Scheme for the Common Name Resolution Protocol

📅 published August 2002, from ietf

The 'go' URI Scheme for the Common Name Resolution Protocol 🎀

  • RFC: 3368 🦋
  • Authors: M. Mealling (Michael Mealling), VeriSign, Inc. 💅
  • Category: Standards Track ✨
  • Date: August 2002 🌸
  • Obsoletes / Updates: The title block has no Obsoletes or Updates line, so this one doesn't list any. 🙈

Network Working Group is the group that put this out. Bestie, this is the spec that defines the go: URI scheme for CNRP, and it's giving main character energy 👑

Status of This Memo

This document is an Internet standards track protocol for the Internet community, and it's open for discussion and suggestions for improvements. For the standardization state and status of this protocol, check the current edition of "Internet Official Protocol Standards" (STD 1). Distribution of this memo is unlimited. 💖

Copyright (C) The Internet Society (2002). All Rights Reserved. 🌈

Abstract

So this doc defines a URI scheme called go: for use with the Common Name Resolution Protocol. It breaks down the syntax parts and explains how URI Resolution uses them to find the transports available for a CNRP service 🧚 Some of the URI components look like parts you've seen in other URI schemes, but they often don't act like them, so you have to be careful 💀 Honestly, the go scheme has more in common with the location independent news scheme than with any other URI scheme ✨

Table of Contents 📖

1.    Goals  . . . . . . . . . . . . . . . . . . . . . . . . . . .  2
2.    Terminology  . . . . . . . . . . . . . . . . . . . . . . . .  2
3.    Syntax Rules . . . . . . . . . . . . . . . . . . . . . . . .  3
3.1   General Syntax . . . . . . . . . . . . . . . . . . . . . . .  3
3.2   ABNF Grammar . . . . . . . . . . . . . . . . . . . . . . . .  3
3.3   Special Cases and Default Values . . . . . . . . . . . . . .  4
3.3.1 If There is Only a Server  . . . . . . . . . . . . . . . . .  4
3.3.2 If Server is Empty Then server=localhost . . . . . . . . . .  4
3.3.3 Default Port . . . . . . . . . . . . . . . . . . . . . . . .  4
3.4   Encoding Rules . . . . . . . . . . . . . . . . . . . . . . .  4
4.    Transport Independence . . . . . . . . . . . . . . . . . . .  4
5.    Examples . . . . . . . . . . . . . . . . . . . . . . . . . .  4
6.    Security Considerations  . . . . . . . . . . . . . . . . . .  5
7.    IANA Considerations  . . . . . . . . . . . . . . . . . . . .  5
      References . . . . . . . . . . . . . . . . . . . . . . . . .  6
A.    Registration Template  . . . . . . . . . . . . . . . . . . .  7
      Author's Address . . . . . . . . . . . . . . . . . . . . . .  7
      Full Copyright Statement . . . . . . . . . . . . . . . . . .  8

1. Goals 🎯

The two goals of the CNRP [3] URI [1] are to identify a specific common-name record at a specific server, and to identify a query or entry point into the query process that might be dynamic. Since CNRP requires that the ID be a core query term, both of these cases can be boiled down to just a query that contains only the ID of the item 💅

Okay, so at first glance it seems like it'd be easy to canonicalize the XML encoded query and then stick it in the query portion of the URL. The problem is that, because of the encoding rules, anything even slightly complex will blow past the URI length limitations 😭 So the suggested fix is a simplified query syntax that's a subset of what the XML can do 🫶

2. Terminology 📝

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 [4]. 🌸

3. Syntax Rules 🎀

3.1 General Syntax 🦋

The CNRP URI comes in two forms. The first form is for talking to a specific server. The second form is for expressing a query that's meant to go out to several different CNRP services. The two examples below are just for teaching purposes. The complete ABNF grammar in Section 3.2 is the only authoritative syntax definition, bestie 🧠

go://[<host>]?[<common-name>]*[;<attribute>=[<type>,]<value>]

and

go:<common-name>*[;<attribute>=[<type>,]<value>]

3.2 ABNF Grammar 💖

Here's the full ABNF [2] grammar. Some values are pulled in by reference from RFC 2396 [1] ✨

cnrp-uri      = "go:" (form1 / form2)
form1         = "//" [server] ["?" ((common-name *avpair) / id-req) ]
form2         = common-name *avpair

id-req        = "id=" value
avpair        = ";" attribute "=" [ type "," ] value

server        = // as specified in RFC2396

common-name     = *(unreserved | escaped)
attribute       = *(unreserved | escaped)
value           = *(unreserved | escaped)
type            = *(unreserved | escaped)

unreserved      = // as specified in RFC2396

escaped       = "%" hex hex
hex           = "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" |
                "8" | "9" | "A" | "B" | "C" | "D" | "E" | "F" |
                "a" | "b" | "c" | "d" | "e" | "f"

3.3 Special Cases and Default Values 🍓

3.3.1 If There is Only a Server 🧚

If the CNRP URI only has the server production, then the URI identifies a given CNRP server and not any particular query that's going to be run. A client can assume this server will at least answer the 'servicequery' request 🥰

3.3.2 If Server is Empty Then server=localhost 🌈

If the 'server' element has no value, then its value MUST be assumed to be "localhost". 🏡

3.3.3 Default Port 🔌

CNRP's well known HTTP transport port is 1096. If the port value portion of the server production isn't specified, then port 1096 SHOULD be used if the client has no prior knowledge about other ports or transports the service may support 💜

3.4 Encoding Rules 🔤

The common-name, query parameters, and parameter values must be encoded using the UTF-8 encoding scheme [5]. Any octet that isn't one of the permitted characters per the grammar above MUST instead be represented by a "%" followed by two characters from the <hex> character set above. The two characters give the hexadecimal representation of that octet 🫠

4. Transport Independence 🚀

As the CNRP protocol specification [3] says, CNRP can be expressed over multiple transport protocols, with HTTP being mandatory to implement. When a client tries to resolve a CNRP URI and it knows nothing about the service being referenced in that URI, then it SHOULD use HTTP on the CNRP default port (1096) 💖

5. Examples 🍭

Here are the examples, bestie 👀

go:Mercedes%20Benz

This example is a general query for the common-name "Mercedes Benz". The query is meant to be packaged with any client-provided defaults and sent to the one or more services the client has configured to ask 💅

go://?Mercedes%20Benz

This example is a general query for the common-name "Mercedes Benz" that gets sent to the server running on 'localhost' 🏠

go://cnrp.foo.com?Mercedes%20Benz;geography=US-ga

This example is a query for the common-name "Mercedes Benz" in the geographic area "US-ga", which should be sent to the server found at cnrp.foo.com 🗺️

go://cnrp.foo.org?Martin%20J.%20D%C3%BCrst

This example has a UTF-8 character encoded using hex escaping. The value encoded is a u-umlaut (a 'u' with two dots over it). This simple query is sent to the server found at cnrp.foo.org with no parameters 🦄

go://cnrp.foo.com?id=5432345

Here only an id is given, which means this example points directly at a particular common-name record on a particular server. This example would probably be found in a link on a web page of some type 🔗

6. Security Considerations 🔐

Bestie, this section is serious business. Please read it all 🚨

In addition to the security considerations inherent in CNRP itself (see the Security Considerations section of RFC 3367 [3]), the URI mechanism can also be used to retrieve a URI identifying some other site, by including just the ID and not the common-name being linked to. I.e., the user may think they're being shown the URI currently mapped to the "BMW" common-name. But when only the ID is used, the actual common-name isn't part of the URI, which makes it possible to use a CNRP URI without knowing which common-name it's referring to 😱

7. IANA Considerations 🏛️

The IANA is asked to register the URL registration template found in Appendix A in accordance with RFC 2717 [6]. 🫶

References 📚

  • [1] Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform Resource Identifiers (URI): Generic Syntax", RFC 2396, August 1998.
  • [2] Crocker, D., "Augmented BNF for Syntax Specifications: ABNF", RFC 2234, November 1997.
  • [3] Popp, N., Mealling, M. and M. Moseley, "Common Name Resolution Protocol (CNRP)", RFC 3367, August 2002.
  • [4] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.
  • [5] The Unicode Consortium, "The Unicode Standard, Version 2.0: Appendix A.2", ISBN 0-201-48345-9, January 1988.
  • [6] Petke, R. and I. King, "Registration Procedures for URL Scheme Names", BCP 35, RFC 2717, November 1999.

Appendix A. Registration Template 🧾

URL scheme name: go

URL scheme syntax: Section 3.2

Character encoding considerations: Section 3.4

Intended usage: Section 1

Applications and/or protocols which use this scheme: [3]

Interoperability considerations: None not specified in [3]

Security considerations: Section 6

Relevant publications: [3]

Contact: CNRP Working Group

Author/Change Controller: IESG

Author's Address 💌

Michael Mealling
VeriSign, Inc.
21345 Ridgetop Circle
Dulles, VA  20170
US

Phone: (703) 742-0400
EMail: michael@verisignlabs.com

Copyright (C) The Internet Society (2002). All Rights Reserved.

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