RFC3252 - Binary Lexical Octet Ad-hoc Transport

王朝other·作者佚名 2008-05-31

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Network Working Group H. Kennedy

Request for Comments: 3252 Mimezine

Category: Informational 1 April 2002

Binary Lexical Octet Ad-hoc Transport

Status of this Memo

This memo provides information for the Internet community. It does

not specify an Internet standard of any kind. Distribution of this

memo is unlimited.

Abstract

This document defines a reformulation of IP and two transport layer

protocols (TCP and UDP) as XML applications.

1. IntrodUCtion

1.1. Overview

This document describes the Binary Lexical Octet Ad-hoc Transport

(BLOAT): a reformulation of a widely-deployed network-layer protocol

(IP [RFC791]), and two associated transport layer protocols (TCP

[RFC793] and UDP [RFC768]) as XML [XML] applications. It also

describes methods for transporting BLOAT over Ethernet and IEEE 802

networks as well as encapsulating BLOAT in IP for gatewaying BLOAT

across the public Internet.

1.2. Motivation

The wild popularity of XML as a basis for application-level protocols

such as the Blocks Extensible Exchange Protocol [RFC3080], the Simple

Object Access Protocol [SOAP], and Jabber [JABBER] prompted

investigation into the possibility of extending the use of XML in the

protocol stack. Using XML at both the transport and network layer in

addition to the application layer would provide for an amazing amount

of power and flexibility while removing dependencies on proprietary

and hard-to-understand binary protocols. This protocol unification

would also allow applications to use a single XML parser for all

ASPects of their operation, eliminating developer time spent figuring

out the intricacies of each new protocol, and moving the hard work of

parsing to the XML toolset. The use of XML also mitigates concerns

over "network vs. host" byte ordering which is at the root of many

network application bugs.

1.3. Relation to Existing Protocols

The reformulations specified in this RFCfollow as closely as

possible the spirit of the RFCs on which they are based, and so MAY

contain elements or attributes that would not be needed in a pure

reworking (e.g. length attributes, which are implicit in XML.)

The layering of network and transport protocols are maintained in

this RFCdespite the optimizations that could be made if the line

were somewhat blurred (i.e. merging TCP and IP into a single, larger

element in the DTD) in order to foster future use of this protocol as

a basis for reformulating other protocols (such as ICMP.)

Other than the encoding, the behavioral aspects of each of the

existing protocols remain unchanged. Routing, address spaces, TCP

congestion control, etc. behave as specified in the extant standards.

Adapting to new standards and eXPerimental algorithm heuristics for

improving performance will become much easier once the move to BLOAT

has been completed.

1.4. Requirement Levels

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 BCP 14, RFC2119

[RFC2119].

2. IPoXML

This protocol MUST be implemented to be compliant with this RFC.

IPoXML is the root protocol REQUIRED for effective use of TCPoXML

(section 3.) and higher-level application protocols.

The DTD for this document type can be found in section 7.1.

The routing of IPoXML can be easily implemented on hosts with an XML

parser, as the regular structure lends itself handily to parsing and

validation of the document/datagram and then processing the

destination address, TTL, and checksum before sending it on to its

next-hop.

The reformulation of IPv4 was chosen over IPv6 [RFC2460] due to the

wider deployment of IPv4 and the fact that implementing IPv6 as XML

would have exceeded the 1500 byte Ethernet MTU.

All BLOAT implementations MUST use - and specify - the UTF-8 encoding

of RFC2279 [RFC2279]. All BLOAT document/datagrams MUST be well-

formed and include the XMLDecl.

2.1. IP Description

A number of items have changed (for the better) from the original IP

specification. Bit-masks, where present have been converted into

human-readable values. IP addresses are listed in their dotted-

decimal notation [RFC1123]. Length and checksum values are present

as decimal integers.

To calculate the length and checksum fields of the IP element, a

canonicalized form of the element MUST be used. The canonical form

SHALL have no whitespace (including newline characters) between

elements and only one space character between attributes. There

SHALL NOT be a space following the last attribute in an element.

An iterative method SHOULD be used to calculate checksums, as the

length field will vary based on the size of the checksum.

The payload element bears special attention. Due to the character

set restrictions of XML, the payload of IP datagrams (which MAY

contain arbitrary data) MUST be encoded for transport. This RFC

REQUIRES the contents of the payload to be encoded in the base-64

encoding of RFC2045 [RFC2045], but removes the requirement that the

encoded output MUST be wrapped on 76-character lines.

2.2. Example Datagram

The following is an example IPoXML datagram with an empty payload:

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE ip PUBLIC "-//IETF//DTD BLOAT 1.0 IP//EN" "bloat.dtd">

<ip>

<tos precedence="Routine" delay="Normal" throughput="Normal"

relibility="Normal" reserved="0"/>

<total.length value="461"/>

</options>

</header>

</payload>

</ip>

3. TCPoXML

This protocol MUST be implemented to be compliant with this RFC. The

DTD for this document type can be found in section 7.2.

3.1. TCP Description

A number of items have changed from the original TCP specification.

Bit-masks, where present have been converted into human-readable

values. Length and checksum and port values are present as decimal

integers.

To calculate the length and checksum fields of the TCP element, a

canonicalized form of the element MUST be used as in section 2.1.

An iterative method SHOULD be used to calculate checksums as in

section 2.1.

The payload element MUST be encoded as in section 2.1.

The TCP offset element was expanded to a maximum of 255 from 16 to

allow for the increased size of the header in XML.

TCPoXML datagrams encapsulated by IPoXML MAY omit the <?xml?> header

as well as the <!DOCTYPE> declaration.

3.2. Example Datagram

The following is an example TCPoXML datagram with an empty payload:

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE tcp PUBLIC "-//IETF//DTD BLOAT 1.0 TCP//EN" "bloat.dtd">

<tcp>

<tcp.header>

<tcp.options>

<tcp.end kind="0"/>

</tcp.options>

</tcp.header>

</payload>

</tcp>

4. UDPoXML

This protocol MUST be implemented to be compliant with this RFC. The

DTD for this document type can be found in section 7.3.

4.1. UDP Description

A number of items have changed from the original UDP specification.

Bit-masks, where present have been converted into human-readable

values. Length and checksum and port values are present as decimal

integers.

To calculate the length and checksum fields of the UDP element, a

canonicalized form of the element MUST be used as in section 2.1. An

iterative method SHOULD be used to calculate checksums as in section

2.1.

The payload element MUST be encoded as in section 2.1.

UDPoXML datagrams encapsulated by IPoXML MAY omit the <?xml?> header

as well as the <!DOCTYPE> declaration.

4.2. Example Datagram

The following is an example UDPoXML datagram with an empty payload:

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE udp PUBLIC "-//IETF//DTD BLOAT 1.0 UDP//EN" "bloat.dtd">

<udp>

<udp.header>

<udp.length value="143"/>

</udp.header>

</payload>

</udp>

5. Network Transport

This document provides for the transmission of BLOAT datagrams over

two common families of physical layer transport. Future RFCs will

address additional transports as routing vendors catch up to the

specification, and we begin to see BLOAT routed across the Internet

backbone.

5.1. Ethernet

BLOAT is encapsulated in Ethernet datagrams as in [RFC894] with the

exception that the type field of the Ethernet frame MUST contain the

value 0xBEEF. The first 5 octets of the Ethernet frame payload will

be 0x3c 3f 78 6d 6c ("<?xml".)

5.2. IEEE 802

BLOAT is encapsulated in IEEE 802 Networks as in [RFC1042] except

that the protocol type code for IPoXML is 0xBEEF.

6. Gatewaying over IP

In order to facilitate the gradual introduction of BLOAT into the

public Internet, BLOAT MAY be encapsulated in IP as in [RFC2003] to

gateway between networks that run BLOAT natively on their LANs.

7. DTDs

The Transport DTDs (7.2. and 7.3.) build on the definitions in the

Network DTD (7.1.)

The DTDs are referenced by their PubidLiteral and SystemLiteral (from

[XML]) although it is understood that most IPoXML implementations

will not need to pull down the DTD, as it will normally be embedded

in the implementation, and presents something of a catch-22 if you

need to load part of your network protocol over the network.

7.1. IPoXML DTD

<!--

DTD for IP over XML.

Refer to this DTD as:

<!DOCTYPE ip PUBLIC "-//IETF//DTD BLOAT 1.0 IP//EN" "bloat.dtd">

-->

<!--

DTD data types:

Digits [0..9]+

Precedence "NetworkControl InternetworkControl

CRITIC FlashOverride Flash Immediate

Priority Routine"

IP4Addr "dotted-decimal" notation of [RFC1123]

Class [0..3]

Sec "Unclassified Confidential EFTO MMMM PROG

Restricted Secret Top Secret Reserved"

Compartments [0..65535]

Handling [0..65535]

TCC [0..16777216]

-->

<!ENTITY % Digits "CDATA">

<!ENTITY % Precedence "CDATA">

<!ENTITY % IP4Addr "CDATA">

<!ENTITY % Class "CDATA">

<!ENTITY % Sec "CDATA">

<!ENTITY % Compartments "CDATA">

<!ENTITY % Handling "CDATA">

<!ENTITY % TCC "CDATA">

<!ELEMENT ip (header, payload)>

<!ELEMENT header (version, tos, total.length, id, flags, offset, ttl,

protocol, checksum, source, destination, options,

padding)>

<!ATTLIST header

length %Digits; #REQUIRED>

<!ELEMENT version EMPTY>

<!ATTLIST version

value %Digits; #REQUIRED>

<!ELEMENT tos EMPTY>

<!ATTLIST tos

precedence %Precedence; #REQUIRED

delay (normal low) #REQUIRED

throughput (normal high) #REQUIRED

relibility (normal high) #REQUIRED

reserved CDATA #FIXED "0">

<!ELEMENT total.length EMPTY>

<!--

total length of datagram (header and payload) in octets, MUST be

less than 65,535 (and SHOULD be less than 1024 for IPoXML on local

ethernets).

-->

<!ATTLIST total.length

value %Digits; #REQUIRED>

<!ELEMENT id EMPTY>

<!ATTLIST id

value %Digits; #REQUIRED>

<!ELEMENT flags EMPTY>

<!ATTLIST flags

reserved CDATA #FIXED "0"

df (maydont) #REQUIRED

mf (lastmore) #REQUIRED>

<!ELEMENT offset EMPTY>

<!ATTLIST offset

value %Digits; #REQUIRED>

<!ELEMENT ttl EMPTY>

<!ATTLIST ttl

value %Digits; #REQUIRED>

<!ELEMENT protocol EMPTY>

<!ATTLIST protocol

value %Digits; #REQUIRED>

<!ELEMENT checksum EMPTY>

<!ATTLIST checksum

value %Digits; #REQUIRED>

<!ELEMENT source EMPTY>

<!ATTLIST source

address %IP4Addr; #REQUIRED>

<!ELEMENT destination EMPTY>

<!ATTLIST destination

address %IP4Addr; #REQUIRED>

<!ELEMENT options ( end noop security loose strict record

stream timestamp )*>

<!ELEMENT end EMPTY>

<!ATTLIST end

copied (01) #REQUIRED

class CDATA #FIXED "0"

number CDATA #FIXED "0">

<!ELEMENT noop EMPTY>

<!ATTLIST noop

copied (01) #REQUIRED

class CDATA #FIXED "0"

number CDATA #FIXED "1">

<!ELEMENT security EMPTY>

<!ATTLIST security

copied CDATA #FIXED "1"

class CDATA #FIXED "0"

number CDATA #FIXED "2"

length CDATA #FIXED "11"

security %Sec; #REQUIRED

compartments %Compartments; #REQUIRED

handling %Handling; #REQUIRED

tcc %TCC; #REQUIRED>

<!ELEMENT loose (hop)+>

<!ATTLIST loose

copied CDATA #FIXED "1"

class CDATA #FIXED "0"

number CDATA #FIXED "3"

length %Digits; #REQUIRED

pointer %Digits; #REQUIRED>

<!ELEMENT hop EMPTY>

<!ATTLIST hop

address %IP4Addr; #REQUIRED>

<!ELEMENT strict (hop)+>

<!ATTLIST strict

copied CDATA #FIXED "1"

class CDATA #FIXED "0"

number CDATA #FIXED "9"

length %Digits; #REQUIRED

pointer %Digits; #REQUIRED>

<!ELEMENT record (hop)+>

<!ATTLIST record

copied CDATA #FIXED "0"

class CDATA #FIXED "0"

number CDATA #FIXED "7"

length %Digits; #REQUIRED

pointer %Digits; #REQUIRED>

<!ELEMENT stream EMPTY>

<!ATTLIST stream

copied CDATA #FIXED "1"

class CDATA #FIXED "0"

number CDATA #FIXED "8"

length CDATA #FIXED "4"

id %Digits; #REQUIRED>

<!ELEMENT timestamp (tstamp)+>

<!ATTLIST timestamp

copied CDATA #FIXED "0"

class CDATA #FIXED "2"

number CDATA #FIXED "4"

length %Digits; #REQUIRED

pointer %Digits; #REQUIRED

oflw %Digits; #REQUIRED

flag (0 1 3) #REQUIRED>

<!ELEMENT tstamp EMPTY>

<!ATTLIST tstamp

time %Digits; #REQUIRED

address %IP4Addr; #IMPLIED>

<!--

padding to bring header to 32-bit boundary.

pad MUST be "0"*

-->

<!ELEMENT padding EMPTY>

<!ATTLIST padding

pad CDATA #REQUIRED>

<!-- payload MUST be encoded as base-64 [RFC2045], as modified

by section 2.1 of this RFC-->

<!ELEMENT payload (CDATA)>

7.2. TCPoXML DTD

<!--

DTD for TCP over XML.

Refer to this DTD as:

<!DOCTYPE tcp PUBLIC "-//IETF//DTD BLOAT 1.0 TCP//EN" "bloat.dtd">

-->

<!ELEMENT tcp (tcp.pseudoheader?, tcp.header, payload)>

<!ELEMENT tcp.header (src, dest, sequence, acknowledgement, offset,

reserved, control, window, checksum, urgent,

tcp.options, padding)>

<!ELEMENT src EMPTY>

<!ATTLIST src

port %Digits; #REQUIRED>

<!ELEMENT dest EMPTY>

<!ATTLIST dest

port %Digits; #REQUIRED>

<!ELEMENT sequence EMPTY>

<!ATTLIST sequence

number %Digits; #REQUIRED>

<!ELEMENT acknowledgement EMPTY>

<!ATTLIST acknowledgement

number %Digits; #REQUIRED>

<!ELEMENT offset EMPTY>

<!ATTLIST offset

number %Digits; #REQUIRED>

<!ELEMENT reserved EMPTY>

<!ATTLIST reserved

value CDATA #FIXED "0">

<!ELEMENT control EMPTY>

<!ATTLIST control

urg (01) #IMPLIED

ack (01) #IMPLIED

psh (01) #IMPLIED

rst (01) #IMPLIED

syn (01) #IMPLIED

fin (01) #IMPLIED>

<!ELEMENT window EMPTY>

<!ATTLIST window

size %Digits; #REQUIRED>

<!--

checksum as in ip, but with

the following pseudo-header added into the tcp element:

-->

<!ELEMENT tcp.pseudoheader (source, destination, protocol,

tcp.length)>

<!--

tcp header + data length in octets. does not include the size of

the pseudoheader.

-->

<!ELEMENT tcp.length EMPTY>

<!ATTLIST tcp.length

value %Digits; #REQUIRED>

<!ELEMENT urgent EMPTY>

<!ATTLIST urgent

pointer %Digits; #REQUIRED>

<!ELEMENT tcp.options (tcp.end tcp.noop tcp.mss)+>

<!ELEMENT tcp.end EMPTY>

<!ATTLIST tcp.end

kind CDATA #FIXED "0">

<!ELEMENT tcp.noop EMPTY>

<!ATTLIST tcp.noop

kind CDATA #FIXED "1">

<!ELEMENT tcp.mss EMPTY>

<!ATTLIST tcp.mss

kind CDATA #FIXED "2"

length CDATA #FIXED "4"

size %Digits; #REQUIRED>

7.3. UDPoXML DTD

<!--

DTD for UDP over XML.

Refer to this DTD as:

<!DOCTYPE udp PUBLIC "-//IETF//DTD BLOAT 1.0 UDP//EN" "bloat.dtd">

-->

<!ELEMENT udp (udp.pseudoheader?, udp.header, payload)>

<!ELEMENT udp.header (src, dest, udp.length, checksum)>

<!ELEMENT udp.pseudoheader (source, destination, protocol,

udp.length)>

<!--

udp header + data length in octets. does not include the size of

the pseudoheader.

-->

<!ELEMENT udp.length EMPTY>

<!ATTLIST udp.length

value %Digits; #REQUIRED>

8. Security Considerations

XML, as a subset of SGML, has the same security considerations as

specified in SGML Media Types [RFC1874]. Security considerations

that apply to IP, TCP and UDP also likely apply to BLOAT as it does

not attempt to correct for issues not related to message format.

9. References

[JABBER] Miller, J., "Jabber", draft-miller-jabber-00.txt,

February 2002. (Work in Progress)

[RFC768] Postel, J., "User Datagram Protocol", STD 6, RFC768,

August 1980.

[RFC791] Postel, J., "Internet Protocol", STD 5, RFC791,

September 1981.

[RFC793] Postel, J., "Transmission Control Protocol", STD 7, RFC

793, September 1981.

[RFC894] Hornig, C., "Standard for the Transmission of IP

Datagrams over Ethernet Networks.", RFC894, April 1984.

[RFC1042] Postel, J. and J. Reynolds, "Standard for the

Transmission of IP Datagrams Over IEEE 802 Networks", STD

43, RFC1042, February 1988.

[RFC1123] Braden, R., "Requirements for Internet Hosts -

Application and Support", RFC1123, October 1989.

[RFC1874] Levinson, E., "SGML Media Types", RFC1874, December

1995.

[RFC2003] Perkins, C., "IP Encapsulation within IP", RFC2003,

October 1996.

[RFC2045] Freed, N. and N. Borenstein, "Multipurpose Internet Mail

Extensions (MIME) Part One: Format of Internet Message

Bodies", RFC2045, November 1996.

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate

Requirement Levels", BCP 14, RFC2119, March 1997.

[RFC2279] Yergeau, F., "UTF-8, a transformation format of ISO

10646", RFC2279, January 1998.

[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6

(IPv6) Specification", RFC2460, December 1998.

[RFC3080] Rose, M., "The Blocks Extensible Exchange Protocol Core",

RFC3080, March 2001.

[SOAP] Box, D., Ehnebuske, D., Kakivaya, G., Layman, A.,

Mendelsohn, N., Nielsen, H. F., Thatte, S. Winer, D.,

"Simple Object Access Protocol (SOAP) 1.1" World Wide Web

Consortium Note, May 2000 http://www.w3.org/TR/SOAP/

[XML] Bray, T., Paoli, J., Sperberg-McQueen, C. M., "Extensible

Markup Language (XML)" World Wide Web Consortium

Recommendation REC- xml-19980210.

http://www.w3.org/TR/1998/REC-xml-19980210

10. Author's Address

Hugh Kennedy

Mimezine

1060 West Addison

Chicago, IL 60613

USA

EMail: kennedyh@engin.umich.edu

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