Internet DRAFT - draft-hedberg-spocp-tcp
draft-hedberg-spocp-tcp
Network Working Group R. Hedberg
Internet-Draft Stockholm University
Expires: July 1, 2004 January 2004
Simple Policy Control Protocol over TCP/IP
draft-hedberg-spocp-tcp-00
Status of this Memo
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026.
Internet-Drafts are working documents of the Internet Engineering
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This Internet-Draft will expire on July 1, 2004.
Copyright Notice
Copyright (C) The Internet Society (2004). All Rights Reserved.
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Table of Contents
1. Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Protocol implementation . . . . . . . . . . . . . . . . . . . . 4
3. Security considerations . . . . . . . . . . . . . . . . . . . . 5
References . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 6
A. Simple examples . . . . . . . . . . . . . . . . . . . . . . . . 7
Intellectual Property and Copyright Statements . . . . . . . . . 8
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1. Abstract
The SPOCP protocol has been described in [SPOCP]. The description is
done in general terms and is not done in such a way that implementers
can directly implement the protocol. To make that possible there has
to be a mapping defined between the more abstract description and a
bits on the wire description. This document represents one possible
mapping.
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2. Protocol implementation
We have choosen a very simple base for our approach: namely to use as
a common structure tuples, consisting of a length and a value (LV).
The format of the length part is the printable representation of the
length and the value is then a variable length value field. The
boarder between the length and the value is denoted by a ':' (0x3A) .
So, the string "foobar" would be represented by the LV "6:foobar".
The reason for choosing this format is of course that the Spocp
server must anyway be able to parse canonical S-expressions [SPOCP
Sexp] and there for already has the capability to parse LV's. So no
extra code is needed for decoding this format. The other benefit is
that the server and the client, after having read a couple of bytes
of a command or response from the net, knows how many bytes it must
read before it has all the information. For the client if a multipart
response is received there is no length field telling how big the
combined length of all the parts is. Each part is coded separately.
More general, a protocol operations in SPOCP which consists of a
operand and a set of zero or more arguments will be represented using
the format:
L(L'Operand' *L'arg')
For example (using the canonical s-expression representation) the
permission check:
QUERY (4:http(4:page10:index.html)(6:action3:GET)(6:userid4:olav))
Would be represented as
70:5:QUERY60:(4:http(4:page10:index.html)(6:action3:GET)(6:userid4:olav))
The server is quiet unless the client sends a query. That is, no
initial greeting is sent from the server.
*Note:* As of this moment there is no default SPOCP port defined.
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3. Security considerations
This document is about how the SPOCP protocol is to be coded on the
wire. Security concerns with the protocol itself and the usage of a
generalized access control service is delt with in [SPOCP] and [SPOCP
Sexp].
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References
[SPOCP Sexp]
Hedberg, R. and O. Bandmann, "Restricted S-expressions for
usage in a generalized access control service".
[SPOCP] Hedberg, R., "The Simple Policy Control Protocol".
Author's Address
Roland Hedberg
Stockholm University
Kasamark 114
Umea 90586
Sweden
Phone: +46 90 147275
EMail: roland@it.su.se
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Appendix A. Simple examples
C: marks what the client sends and S: the replies from the server.
Adding a new rule:
C: 49:3:ADD41:(4:http(4:page)(6:action3:GET)(6:userid))
S: 9:3:2002:Ok
A typical query session:
C:
70:5:QUERY60:(4:http(4:page10:index.html)(6:action3:GET)(6:userid4:olav))
S: 9:3:2002:Ok
C: 8:6:LOGOUT
S: 10:3:2033:Bye
If the client wants to keep the connection open in order to send more
queries it just does not send and LOGOUT command.
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Intellectual Property Statement
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Acknowledgment
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