RFC 5024 - ODETTE File Transfer Protocol 2.0
(Formats: TXT)
Network Working Group I. Friend
Request for Comments: 5024 ODETTE
Obsoletes: 2204 November 2007
Category: Informational
|
ODETTE File Transfer Protocol 2
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.
IESG Note
This RFC is not a candidate for any level of Internet Standard. The
IETF disclaims any knowledge of the fitness of this RFC for any
purpose and in particular notes that the decision to publish is not
based on IETF review for such things as security, congestion control,
or inappropriate interaction with deployed protocols. The RFC Editor
has chosen to publish this document at its discretion. Readers of
this document should exercise caution in evaluating its value for
implementation and deployment. See RFC 3932 for more information.
Abstract
This memo updates the ODETTE File Transfer Protocol, an established
file transfer protocol facilitating electronic data interchange of
business data between trading partners, to version 2.
The protocol now supports secure and authenticated communication over
the Internet using Transport Layer Security, provides file
encryption, signing, and compression using Cryptographic Message
Syntax, and provides signed receipts for the acknowledgement of
received files.
The protocol supports both direct peer-to-peer communication and
indirect communication via a Value Added Network and may be used with
TCP/IP, X.25, and ISDN-based networks.
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Table of Contents
1. Introduction ....................................................4
1.1. Background .................................................4
1.2. Summary of Features ........................................5
1.3. General Principles .........................................5
1.4. Structure ..................................................6
1.5. Virtual Files ..............................................6
1.6. Service Description ........................................9
1.7. Security ...................................................9
2. Network Service ................................................11
2.1. Introduction ..............................................11
2.2. Service Primitives ........................................11
2.3. Secure ODETTE-FTP Session .................................12
2.4. Port Assignment ...........................................12
3. File Transfer Service ..........................................13
3.1. Model .....................................................13
3.2. Session Setup .............................................14
3.3. File Transfer .............................................16
3.4. Session Take Down .........................................20
3.5. Service State Automata ....................................23
4. Protocol Specification .........................................28
4.1. Overview ..................................................28
4.2. Start Session Phase .......................................28
4.3. Start File Phase ..........................................30
4.4. Data Transfer Phase .......................................34
4.5. End File Phase ............................................35
4.6. End Session Phase .........................................36
4.7. Problem Handling ..........................................36
5. Commands and Formats ...........................................37
5.1. Conventions ...............................................37
5.2. Commands ..................................................37
5.3. Command Formats ...........................................37
5.4. Identification Code .......................................68
6. File Services ..................................................69
6.1. Overview ..................................................69
6.2. File Signing ..............................................69
6.3. File Encryption ...........................................70
6.4. File Compression ..........................................70
6.5. V Format Files - Record Lengths ...........................70
7. ODETTE-FTP Data Exchange Buffer ................................71
7.1. Overview ..................................................71
7.2. Data Exchange Buffer Format ...............................71
7.3. Buffer Filling Rules ......................................72
8. Stream Transmission Buffer .....................................73
8.1. Introduction ..............................................73
8.2. Stream Transmission Header Format .........................73
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9. Protocol State Machine .........................................74
9.1. ODETTE-FTP State Machine ..................................74
9.2. Error Handling ............................................75
9.3. States ....................................................76
9.4. Input Events ..............................................79
9.5. Output Events .............................................79
9.6. Local Variables ...........................................80
9.7. Local Constants ...........................................81
9.8. Session Connection State Table ............................82
9.9. Error and Abort State Table ...............................85
9.10. Speaker State Table 1 ....................................86
9.11. Speaker State Table 2 ....................................91
9.12. Listener State Table .....................................93
9.13. Example ..................................................96
10. Miscellaneous .................................................97
10.1. Algorithm Choice .........................................97
10.2. Cryptographic Algorithms .................................97
10.3. Protocol Extensions ......................................97
10.4. Certificate Services .....................................98
11. Security Considerations .......................................98
Appendix A. Virtual File Mapping Example .........................100
Appendix B. ISO 646 Character Subset .............................103
Appendix C. X.25 Specific Information ............................104
C.1. X.25 Addressing Restrictions .............................104
C.2. Special Logic ............................................105
C.3. PAD Parameter Profile ....................................116
Appendix D. OFTP X.25 Over ISDN Recommendation ...................118
D.1. ODETTE ISDN Recommendation ...............................119
D.2. Introduction to ISDN .....................................120
D.3. Equipment Types ..........................................123
D.4. Implementation ...........................................124
Acknowledgements .................................................132
Normative References .............................................132
Informative References ...........................................133
ODETTE Address ...................................................134
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1. Introduction
1.1. Background
The ODETTE File Transfer Protocol (ODETTE-FTP) was defined in 1986 by
working group four of the Organisation for Data Exchange by Tele
Transmission in Europe (ODETTE) to address the electronic data
interchange (EDI) requirements of the European automotive industry.
ODETTE-FTP allows business applications to exchange files on a peer-
to-peer basis in a standardised, purely automatic manner and provides
a defined acknowledgement process on successful receipt of a file.
ODETTE-FTP is not to be confused as a variant of, or similar to, the
Internet FTP [FTP], which provides an interactive means for
individuals to share files and which does not have any sort of
acknowledgement process. By virtue of its interactive nature, lack
of file acknowledgements, and client/server design, FTP does not
easily lend itself to mission-critical environments for the exchange
of business data.
Over the last ten years, ODETTE-FTP has been widely deployed on
systems of all sizes from personal computers to large mainframes
while the Internet has emerged as the dominant international network,
providing high-speed communication at low cost. To match the demand
for EDI over the Internet, ODETTE has decided to extend the scope of
its file transfer protocol to incorporate security functions and
advanced compression techniques to ensure that it remains at the
forefront of information exchange technology.
The protocol now supports secure and authenticated communication over
the Internet using Transport Layer Security, provides file
encryption, signing, and compression using Cryptographic Message
Syntax, and provides signed receipts for the acknowledgement of
received files.
The protocol supports both direct peer-to-peer communication and
indirect communication via a Value Added Network and may be used with
TCP/IP, X.25 and ISDN based networks.
ODETTE-FTP has been defined by the ODETTE Security Working Group
which consists of a number of ODETTE member organisations. All
members have significant operational experience working with and
developing OFTP and EDI solutions.
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1.2. Summary of Features
This memo is a development of version 1.4 of ODETTE-FTP [OFTP] with
these changes/additions:
Session level encryption
File level encryption
Secure authentication
File compression
Signed End to End Response (EERP)
Signed Negative End Response (NERP)
Maximum permitted file size increased to 9 PB (petabytes)
Virtual file description added
Extended error codes
Version 1.4 of ODETTE-FTP included these changes and additions to
version 1.3:
Negative End Response (NERP)
Extended Date and Time stamp
New reason code 14 (File direction refused)
1.3. General Principles
The aim of ODETTE-FTP is to facilitate the transmission of a file
between one or more locations in a way that is independent of the
data communication network, system hardware, and software
environment.
In designing and specifying the protocol, the following factors were
considered.
1. The possible differences of size and sophistication of file
storage and small and large systems.
2. The necessity to work with existing systems (reduce changes to
existing products and allow easy implementation).
3. Systems of different ages.
4. Systems of different manufactures.
5. The potential for growth in sophistication (limit impact and avoid
changes at other locations).
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1.4. Structure
ODETTE-FTP is modelled on the OSI reference model. It is designed to
use the Network Service provided by level 3 of the model and provide
a File Service to the users. Thus, the protocol spans levels 4 to 7
of the model.
The description of ODETTE-FTP contained in this memo is closely
related to the original 'X.25' specification of the protocol and in
the spirit of the OSI model describes:
1. A File Service provided to a User Monitor.
2. A protocol for the exchange of information between peer
ODETTE-FTP entities.
1.5. Virtual Files
Information is always exchanged between ODETTE-FTP entities in a
standard representation called a Virtual File. This allows data
transfer without regard for the nature of the communicating systems.
The mapping of a file between a local and virtual representation will
vary from system to system and is not defined here.
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o---------o
Site | Local |
A | File A |
o---------o
|
o----------------------- Mapping A ------------------------o
| | |
| o---------o |
| | Virtual | |
| | File | |
| o---------o |
| o------------------------------------------------o |
| | | |
| | ODETTE-FTP | |
| | | |
| o------------------------------------------------o |
| o---------o o---------o |
| | Virtual | | Virtual | |
| | File | | File | |
| o---------o o----+----o |
| | | |
o------ Mapping B ------------------------ Mapping C ------o
| |
o---------o o----+----o
| Local | Site Site | Local |
| File B | B C | File C |
o---------o o---------o
A Virtual File is described by a set of attributes identifying and
defining the data to be transferred. The main attributes are
detailed in Sections 1.5.1 to 1.5.4.
1.5.1. Organisation
Sequential
Logical records are presented one after another. ODETTE-FTP must
be aware of the record boundaries.
1.5.2. Identification
Dataset Name
Dataset name of the Virtual File being transferred, assigned by
bilateral agreement.
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Time stamp (HHMMSScccc)
A file qualifier indicating the time the Virtual File was made
available for transmission. The counter (cccc=0001-9999) gives
higher resolution.
Date stamp (CCYYMMDD)
A file qualifier indicating the date the Virtual File was made
available for transmission.
The Dataset Name, Date, and Time attributes are assigned by the
Virtual File's originator and are used to uniquely identify a file.
They are all mandatory and must not be changed by intermediate
locations.
The User Monitor may use the Virtual File Date and Time attributes in
local processes involving date comparisons and calculations. Any
such use falls outside the scope of this protocol.
1.5.3. Record Format
Four record formats are defined:
Fixed (F)
Each record in the file has the same length.
Variable (V)
The records in the file can have different lengths.
Unstructured (U)
The file contains a stream of data. No structure is defined.
Text File (T)
A Text File is defined as a sequence of ASCII characters,
containing no control characters except CR-LF that delimit
lines. A line will not have more than 2048 characters.
1.5.4. Restart
ODETTE-FTP can negotiate the restart of an interrupted Virtual File
transmission. Fixed and Variable format files are restarted on
record boundaries. For Unstructured and Text files, the restart
position is expressed as a file offset in 1K (1024 octet) blocks.
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The restart position is always calculated relative to the start of
the Virtual File.
1.6. Service Description
ODETTE-FTP provides a file transfer service to a User Monitor and in
turn uses the Internet transport layer stream service to communicate
between peers.
These services are specified in this memo using service primitives
grouped into four classes as follows:
Request (RQ) An entity asks the service to do some work.
Indication (IND) A service informs an entity of an event.
Response (RS) An entity responds to an event.
Confirm (CF) A service informs an entity of the response.
Services may be confirmed, using the request, indication, response,
and confirm primitives, or unconfirmed using just the request and
indication primitives.
1.7. Security
ODETTE-FTP provides a number of security services to protect a
Virtual File transmission across a hostile network.
These security services are as follows:
Confidentiality
Integrity
Non-repudiation of receipt
Non-repudiation of origin
Secure authentication
Security services in this specification are implemented as follows:
Session level encryption
File level encryption
Signed files
Signed receipts
Session level authentication
ODETTE-FTP Authentication
Session level encryption provides data confidentiality by encryption
of all the protocol commands and data exchanged between two parties,
preventing a third party from extracting any useful information from
the transmission.
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This session level encryption is achieved by layering ODETTE-FTP over
Transport Layer Security [TLS], distinguishing between secure and
unsecure TCP/IP traffic using different port numbers.
File encryption provides complementary data confidentiality by
encryption of the files in their entirety. Generally, this
encryption occurs prior to transmission, but it is also possible to
encrypt and send files while in session. File encryption has the
additional benefit of allowing a file to remain encrypted outside of
the communications session in which it was sent. The file can be
received and forwarded by multiple intermediaries, yet only the final
destination will be able to decrypt the file. File encryption does
not encrypt the actual protocol commands, so trading partner EDI
codes and Virtual File names are still viewable.
Secure authentication is implemented through the session level
authentication features available in [TLS] and proves the identity of
the parties wishing to communicate.
ODETTE-FTP Authentication also provides an authentication mechanism,
but one that is integral to ODETTE-FTP and is available on all
network infrastructures over which ODETTE-FTP is operated (this is in
contrast to [TLS] which is generally only available over TCP/IP-based
networks). Both parties are required to possess certificates when
ODETTE-FTP Authentication is used.
The security features in ODETTE-FTP 2 are centred around the use of
[X.509] certificates. To take advantage of the complete range of
security services offered in both directions, each party is required
to possess an [X.509] certificate. If the confidentiality of data
between two parties is the only concern, then [TLS] alone can be
used, which allows the party accepting an incoming connection (the
Responder) to be the only partner required to possess a certificate.
For businesses, this means that session level encryption between a
hub and its trading partners can be achieved without requiring all
the trading partners to obtain a certificate, assuming that trading
partners always connect to the hub.
With the exception of [TLS], all the security services work with X.25
and ISDN as transport media. Although nothing technically precludes
[TLS] from working with X.25 or ISDN, implementations are rare.
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2. Network Service
2.1. Introduction
ODETTE-FTP peer entities communicate with each other via the OSI
Network Service or the Transmission Control Protocol Transport
Service [RFC793]. This is described by service primitives
representing request, indication, response, and confirmation actions.
For the Internet environment, the service primitives mentioned below
for the Network Service have to be mapped to the respective Transport
Service primitives. This section describes the Network Service
primitives used by ODETTE-FTP and their relationship to the TCP
interface. In practice, the local transport service application
programming interface will be used to access the TCP service.
2.2. Service Primitives
All network primitives can be directly mapped to the respective
Transport primitives when using TCP.
2.2.1. Network Connection
N_CON_RQ ------> N_CON_IND
N_CON_CF <------ N_CON_RS
This describes the setup of a connection. The requesting ODETTE-FTP
peer uses the N_CON_RQ primitive to request an active OPEN of a
connection to a peer ODETTE-FTP, the Responder, which has previously
requested a passive OPEN. The Responder is notified of the incoming
connection via N_CON_IND and accepts it with N_CON_RS. The requester
is notified of the completion of its OPEN request upon receipt of
N_CON_CF.
Parameters
Request Indication Response Confirmation
---------------------------------------------------------------------
Dest addr ------> same same same
2.2.2. Network Data
N_DATA_RQ ------> N_DATA_IND
Data exchange is an unconfirmed service. The requester passes data
for transmission to the Network Service via the N_DATA_RQ primitive.
The Responder is notified of the availability of data via N_DATA_IND.
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In practice, the notification and receipt of data may be combined,
such as by the return from a blocking read from the network socket.
Parameters
Request Indication
---------------------------------------------------------------------
Data ------------------> same
2.2.3. Network Disconnection
N_DISC_RQ ------> N_DISC_IND
An ODETTE-FTP requests the termination of a connection with the
N_DISC_RQ service primitive. Its peer is notified of the CLOSE by a
N_DISC_IND event. It is recognised that each peer must issue a
N_DISC_RQ primitive to complete the TCP symmetric close procedure.
2.2.4. Network Reset
------> N_RST_IND
An ODETTE-FTP entity is notified of a network error by a N_RST_IND
event. It should be noted that N_RST_IND would also be generated by
a peer RESETTING the connection, but this is ignored here as N_RST_RQ
is never sent to the Network Service by ODETTE-FTP.
2.3. Secure ODETTE-FTP Session
[TLS] provides a mechanism for securing an ODETTE-FTP session over
the Internet or a TCP network. ODETTE-FTP is layered over [TLS],
distinguishing between secure and unsecure traffic by using different
server ports.
The implementation is very simple. Layer ODETTE-FTP over [TLS] in
the same way as layering ODETTE-FTP over TCP/IP. [TLS] provides both
session encryption and authentication, both of which may be used by
the connecting parties. A party acts as a [TLS] server when
receiving calls and acts as a [TLS] client when making calls. When
the [TLS] handshake has completed, the responding ODETTE-FTP may
start the ODETTE-FTP session by sending the Ready Message.
2.4. Port Assignment
An ODETTE-FTP requester will select a suitable local port.
The responding ODETTE-FTP will listen for connections on Registered
Port 3305; the service name is 'odette-ftp'.
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The responding ODETTE-FTP will listen for secure TLS connections on
Registered Port 6619; the service name is 'odette-ftps'.
3. File Transfer Service
The File Transfer Service describes the services offered by an
ODETTE-FTP entity to its User Monitor (generally an application).
NOTE: The implementation of the service primitives is an application
issue.
3.1. Model
o-------------------o o-------------------o
| | | |
| USER MONITOR | | USER MONITOR |
| | | |
o-------------------o o-------------------o
| A | A
| | | |
F_XXX_RQ/RS | | F_XXX_IND/CF F_XXX_RQ/RS | | F_XXX_IND/CF
V | V |
o-------------------o o-------------------o
| |- - - - - - >| |
| ODETTE-FTP Entity | E-Buffer | ODETTE-FTP Entity |
| |< - - - - - -| |
o-------------------o o-------------------o
| A | A
N_XXX_RQ/RS | | N_XXX_IND/CF N_XXX_RQ/RS | | N_XXX_IND/CF
| | | |
V | V |
o---------------------------------------------------------o
| |
| N E T W O R K |
| |
o---------------------------------------------------------o
Key: E-Buffer - Exchange Buffer
F_ - File Transfer Service Primitive
N_ - Network Service Primitive
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3.2. Session Setup
3.2.1. Session Connection Service
These diagrams represent the interactions between two communicating
ODETTE-FTP entities and their respective User Agents.
The vertical lines represent the ODETTE-FTP entities. The User
Agents are not shown.
| |
F_CONNECT_RQ ---->|------------|----> F_CONNECT_IND
| |
F_CONNECT_CF <----|------------|<---- F_CONNECT_RS
| |
Parameters
Request Indication Response Confirm
---------------------------------------------------------------------
called-address -> same --- ----
calling-address-> same --- ----
ID1 ------------> same ID2 ------------> same
PSW1------------> same PSW2 -----------> same
mode1 ----------> mode2 ----------> mode3 ----------> same
restart1 -------> same -----------> restart2 -------> same
authentication1-> same -----------> authentication2-> same
---------------------------------------------------------------------
Mode
Specifies the file transfer capabilities of the entity sending or
receiving a F_CONNECT primitive for the duration of the session.
Value:
Sender-only The entity can only send files.
Receiver-only The entity can only receive files.
Both The entity can both send and receive files.
Negotiation:
Sender-only Not negotiable.
Receiver-only Not negotiable.
Both Can be negotiated down to Sender-only or
Receiver-only by the User Monitor or the
ODETTE-FTP entity.
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Request Indication Response Confirm
---------------------------------------------------------------------
Sender-only ----> Receiver-only --> Receiver-only --> Sender-only
Receiver-only --> Sender-only ----> Sender-only ----> Receiver-only
Both -----+-----> Both ----+------> Both -----------> Both
| or +------> Receiver-only --> Sender-only
| or +------> Sender-only ----> Receiver-only
|
or +-----> Receiver-only --> Receiver-only --> Sender-only
or +-----> Sender-only ----> Sender-only ----> Receiver-only
---------------------------------------------------------------------
Restart
Specifies the file transfer restart capabilities of the User
Monitor.
Value:
Y The entity can restart file transfers.
N The entity cannot restart file transfers.
Negotiation:
Request Indication Response Confirm
---------------------------------------------------------------------
restart = Y ----> restart = Y --+-> restart = Y ----> restart = Y
or +-> restart = N ----> restart = N
restart = N ----> restart = N ----> restart = N ----> restart = N
---------------------------------------------------------------------
Authentication
Specifies the authentication requirement of the User Monitor.
Value:
Y Authentication required.
N Authentication not required.
Negotiation: Not negotiable.
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Request Indication Response Confirm
---------------------------------------------------------------------
auth = Y ----> auth = Y ----> auth = Y ----> auth = Y
auth = N ----> auth = N ----> auth = N ----> auth = N
---------------------------------------------------------------------
3.3. File Transfer
3.3.1. File Opening
| |
F_START_FILE_RQ ---->|------------|----> F_START_FILE_IND
| |
F_START_FILE_CF(+|-) <----|------------|<---- F_START_FILE_RS(+|-)
| |
Parameters
Request Ind. RS(+) CF(+) RS(-) CF(-)
------------------------------------------------------------------
filename-------> same ---- ---- ---- ----
date-time------> same ---- ---- ---- ----
destination----> same ---- ---- ---- ----
originator-----> same ---- ---- ---- ----
rec-format-----> same ---- ---- ---- ----
rec-size ------> same ---- ---- ---- ----
file-size------> same ---- ---- ---- ----
org-file-size--> same ---- ---- ---- ----
signed-eerp----> same ---- ---- ---- ----
cipher---------> same ---- ---- ---- ----
sec-services---> same ---- ---- ---- ----
compression----> same ---- ---- ---- ----
envelope-format> same ---- ---- ---- ----
description----> same ---- ---- ---- ----
restart-pos1---> same-> restart-pos2-> same ---- ----
---- ---- ---- ---- cause ------> same
---- ---- ---- ---- retry-later-> same
------------------------------------------------------------------
Notes:
1. Retry-later has values "Y" or "N".
2. Cause is the reason for refusing the transfer (1,..,13,99).
3. Restart-pos1 not equal 0 is only valid if restart has been
agreed during initial negotiation.
4. Restart-pos2 is less than or equal to restart-pos1.
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3.3.2. Data Regime
| |
F_DATA_RQ ---->|------------|----> F_DATA_IND
| |
F_DATA_CF <----|(---CDT----)|
| |
Note: Unlike other commands, where the F_XXX_CF signal is a result of
a corresponding F_XXX_RS command, in this case, the local entity
layer issues this signal when it is ready for the next data
request. This decision is based on the current credit count and
the reception of CDT (Set Credit) from the receiver.
3.3.3. File Closing
| |
F_CLOSE_FILE_RQ --->|------------|----> F_CLOSE_FILE_IND
| |
F_CLOSE_FILE_CF(+|-) <---|------------|<---- F_CLOSE_FILE_RS(+|-)
| |
Parameters
Request Ind RS(+) CF(+) RS(-) CF(-)
---------------------------------------------------------------------
rec-count ---> same ---- ---- ---- ----
unit-count --> same ---- ---- ---- ----
---- ---- Speaker=Y ---> Speaker=N ---- ----
---- ---- Speaker=N ---> Speaker=Y ---- ----
---- ---- ---- ---- cause ---> same
---------------------------------------------------------------------
In a positive Close File response (F_CLOSE_FILE_RS(+)) the current
Listener may either:
1. Set Speaker to "Yes" and become the Speaker or
2. Set Speaker to "No" and remain the Listener.
The File Transfer service will ensure that the setting of the speaker
parameter is consistent with the capabilities of the peer user.
The turn is never exchanged in the case of a negative response or
confirmation.
Only the Speaker is allowed to issue F_XXX_FILE_RQ primitives.
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3.3.4. Exchanging the Turn
3.3.4.1. Initial Turn (First Speaker)
The Initiator becomes the first Speaker at the end of the Session
Setup (F_CONNECT_CF received by Initiator and F_CONNECT_RS sent by
Responder).
3.3.4.2. Following Turns
Rules:
1. At each unsuccessful End of File, the turn is not exchanged.
2. At each successful End of File, the turn is exchanged if requested
by the Listener:
- The current Listener receives F_CLOSE_FILE_IND (Speaker =
choice).
- If the Listener answers F_CLOSE_FILE_RS(Speaker = YES), it
becomes the Speaker, the Speaker receives F_CLOSE_FILE_CF
(Speaker = NO) and becomes the Listener.
- If the Listener answers F_CLOSE_FILE_RS(Speaker = NO), it
remains as the Listener, and the Speaker receives
F_CLOSE_FILE_CF (Speaker = YES) and remains as the Speaker.
3. The Speaker can issue a Change Direction request (F_CD_RQ) to
become the Listener. The Listener receives a Change Direction
indication (F_CD_IND) and becomes the Speaker.
4. In order to prevent loops of F_CD_RQ/IND, the Speaker may not send
an F_CD_RQ after receiving an unsolicited F_CD_IND. If the
Listener receives a solicited F_CD_IND as a result of sending
EFPA(Speaker=Yes), it is acceptable to immediately relinquish the
right to speak by sending an F_CD_RQ.
3.3.5. End to End Response
This service is initiated by the current Speaker (if there is no file
transfer in progress) to send an End to End Response from the final
destination to the originator of a file.
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| |
F_EERP_RQ ---->|------------|----> F_EERP_IND
| |
F_RTR_CF <----|------------|<---- F_RTR_RS
| |
Parameters
Request Indication
------------------------------------
filename -----------> same
date ---------------> same
time ---------------> same
destination --------> same
originator ---------> same
hash ---------------> same
signature ----------> same
------------------------------------
Relationship with Turn:
- Only the Speaker may send an End to End Response request.
- Invoking the EERP service does not change the turn.
- If an F_CD_IND has been received just before F_EERP_RQ is issued,
this results in leaving the special condition created by the
reception of F_CD_IND; i.e., while it was possible to issue
F_RELEASE_RQ and not possible to issue F_CD_RQ just after the
reception of F_CD_IND, after having issued F_EERP_RQ the normal
Speaker status is entered again (F_CD_RQ valid, but F_RELEASE_RQ
not valid).
Notes:
1. The F_EERP_RQ (and also F_NERP_RQ) is confirmed with an F_RTR_CF
signal. The F_RTR_CF signal is common to both F_EERP_RQ and
F_NERP_RQ. There should be no ambiguity, since there can only be
one such request pending at any one time.
2. The signature is optional and is requested when sending the
F_START_FILE_RQ.
3. If it is not possible to sign the EERP, then an unsigned EERP
should still be sent.
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4. It is an application implementation issue to validate the contents
of the EERP and its signature and to decide what action to take on
receipt of an EERP that fails validation or is not signed when a
signed EERP was requested.
3.3.6. Negative End Response
This service is initiated by the current speaker (if there is no file
transfer in progress) to send a Negative End Response when a file
could not be transmitted to the next destination. It is sent only if
the problem is of a non-temporary kind.
This service may also be initiated by the final destination instead
of sending an End to End Response when a file could not be processed,
after having successfully received the file.
| |
F_NERP_RQ ---->|------------|----> F_NERP_IND
| |
F_RTR_CF <----|------------|----- F_RTR_RS
| |
Parameters
Request Indication
---------------------------------------------------
filename ----------------------> same
date --------------------------> same
time --------------------------> same
destination -------------------> same
originator --------------------> same
creator of negative response --> same
reason ------------------------> same
reason text -------------------> same
hash --------------------------> same
signature ---------------------> same
---------------------------------------------------
Relationship with Turn:
The same as for the End-To-End response (see Section 3.3.5).
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3.4. Session Take Down
3.4.1. Normal Close
| |
F_RELEASE_RQ ---->|------------|----> F_RELEASE_IND
| |
Parameters
Request Indication
---------------------------------------------------------------------
reason = normal -------> ----
---------------------------------------------------------------------
The Release service can only be initiated by the Speaker.
The Speaker can only issue a Release request (F_RELEASE_RQ) just
after receiving an unsolicited Change Direction indication
(F_CD_IND). This ensures that the other partner doesn't want to send
any more files in this session.
Peer ODETTE-FTP entities action a normal session release by
specifying Reason = Normal in an End Session (ESID) command.
3.4.2. Abnormal Close
| |
F_RELEASE_RQ ---->|------------|----> F_ABORT_IND
| |
Parameters
Request Indication
---------------------------------------------------------------------
reason = error value --> same (or equivalent)
AO (Abort Origin) = (L)ocal or (D)istant
---------------------------------------------------------------------
Abnormal session release can be initiated by either the Speaker or
the Listener and also by the user or provider.
Abnormal session release can occur at any time within the session.
Peer ODETTE-FTP entities action an abnormal session release by
specifying Reason = Error-value in an End Session (ESID) command.
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The abnormal session release deals with the following types of error:
1. The service provider will initiate an abnormal release in the
following cases:
1. Protocol error.
2. Failure of the Start Session (SSID) negotiation.
3. Command not recognised.
4. Data Exchange Buffer size error.
5. Resources not available.
6. Other unspecified abort code (with Reason = unspecified).
2. The User Monitor will initiate an abnormal release in the
following cases:
1. Local site emergency close down.
2. Resources not available.
3. Other unspecified abort code (with Reason = unspecified).
Other error types may be handled by an abort of the connection.
3.4.3. Abort
| |
F_ABORT_RQ ---->|------------|----> F_ABORT_IND
| |
User-Initiated Abort
| |
F_ABORT_IND <----|------------|----> F_ABORT_IND
| |
Provider-Initiated Abort
Parameters
Request Indication
---------------------------------------------------------------------
-- R (Reason): specified or unspecified
-- AO (Abort Origin): (L)ocal or (D)istant
---------------------------------------------------------------------
The Abort service may be invoked by either entity at any time.
The service provider may initiate an abort in case of error
detection.
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3.4.4. Explanation of Session Take Down Services
User | OFTP | Network | OFTP | User
---------------|------|----------------------|------|---------------
| | | |
1. Normal Release
F_RELEASE_RQ | | ESID(R=normal) | | F_RELEASE_IND
*--------------|-> ==|======================|=> --|-------------->
(R=normal) | | | |
2. User-Initiated Abnormal Release
F_RELEASE_RQ | | ESID(R=error) | | F_ABORT_IND
*--------------|-> ==|======================|=> -|-------------->
(R=error value)| | | | (R=error,AO=D)
3. Provider-Initiated Abnormal Release
F_ABORT_IND | | ESID(R=error) | | F_ABORT_IND
<--------------|-* *=|======================|=> --|-------------->
| | | |
4. User-Initiated Connection Abort
F_ABORT_RQ | | N_DISC_RQ | | F_ABORT_IND
*--------------|-> --|--------->..----------|-> --|-------------->
| | N_DISC_IND | | (R=unsp.,AO=D)
5. Provider-Initiated Connection Abort
F_ABORT_IND | | N_DISC_RQ | | F_ABORT_IND
<--------------|-* *-|--------->..----------|-> --|-------------->
(R=error,AO=L) | | N_DISC_IND | | (R=unsp.,AO=D)
Key: * Origin of command flow
F_ ---> File Transfer Service primitive
N_ ---> Network Service primitive
===> ODETTE-FTP (OFTP) protocol message
3.5. Service State Automata
These state automata define the service as viewed by the User
Monitor. Events causing a state transition are shown in lower case
and the resulting action in upper case where appropriate.
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3.5.1. Idle State Diagram
o------------o
decision | | f_connect_ind
+-----------------| IDLE |-----------------+
| F_CONNECT_RQ | (0) | F_CONNECT_RS |
| o------------o |
V |
o-----------------o |
| | |
| I_WF_FCONNECTCF | |
| | |
o--------+--------o |
| |
| F_CONNECT_CF |
V V
o-----------------o o-----------------o
| | | |
| IDLE SPEAKER | | IDLE LISTENER |
| (1) | | (2) |
| See Speaker | | See Listener |
| State Diagram | | State Diagram |
| | | |
o-----------------o o-----------------o
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3.5.2. Speaker State Diagram
o-----------------o o-----------------o
| IDLE LISTENER | | IDLE |
| CD_RQ just sent | | see (0) |
| see (3), Listen | | Idle |
| State Diagram | | State Diagram |
o-----------------o o-----------------o
A A
| |
decision decision
F_CD_RQ F_RELEASE_RQ
| |
o================o decision o----------o decision o---------------o
| |---------->| WAIT FOR |<----------| |
| | F_EERP_RQ | | F_EERP_RQ | |
| IDLE | | EERP/ | | IDLE |
| SPEAKER | decision | NERP | decision | SPEAKER |
| (1) |---------->| CONFIRM. |<----------| (4) |
| | F_NERP_RQ | | F_NERP_RQ | |
| | | | | |
| | | | | CD_IND |
| | f_rtr_cf | | | just received |
| |<----------| | | |
| | o----------o | |
| | | |
| | | |
o================o o---------------o
A A | |
| | | decision and P2 decision and P2 |
| | +-----------------+ +---------------------+
| | F_START_FILE_RQ | | F_START_FILE_RQ
| | V V
| | o---------------o
| | f_file_start_cf(-) | |
| +----------------------| OPENING |
| | |
| o---------------o
| |
f_file_close_cf(-) or f_start_file_cf(+)
f_file_close_cf(+) and not P1 |
| V
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o---------------o o---------------o record to send o---------o
| | | |------------------>| |
| CLOSING | | DATA TRANSFER | F_DATA_RQ | NEXT |
| | | | | RECORD |
| | | | f_data_cf | |
| | | |<------------------| |
o---------------o o---------------o o---------o
| A |
| | end of file |
| +-------------------+
| F_CLOSE_FILE_RQ
| o-----------------o
| f_file_close_cf(+) and P1 | IDLE LISTENER |
+--------------------------------------------->| see (2), Listen |
| State Diagram |
Predicates: o-----------------o
P1: Positive confirmation and Speaker = YES
P2: Mode = Both or (Mode = Sender-only)
3.5.3 Listener State Diagram
o-----------------o o-----------------o
| IDLE SPEAKER | | IDLE |
| CD_IND just | | |
| received see(4) | | see (0) |
| Speaker State | | Idle |
| Diagram | | State Diagram |
o-----------------o o-----------------o
A A
| |
decision f_eerp_ind decision
F_CD_IND +--------------+ F_RELEASE_IND
| | F_RTR_RS | |
o=================o | o-----------------o
| |<-----------+ | |
| | | |
| | f_nerp_ind | |
| |------------+ | |
| | F_RTR_RS | | |
| | | | |
| |<-----------+ | |
| IDLE LISTENER | f_eerp_ind | IDLE LISTENER |
| (2) |<-----------------------------| (3) |
| | F_RTR_RS | CD_RQ |
| | | just sent |
| | f_nerp_ind | |
| |<-----------------------------| |
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| | F_RTR_RS | |
| | | |
| | f_start_file_ind | |
| | and not P1 | |
| |---------------------+ | |
o=================o F_START_FILE_RS(-) | o-----------------o
A A | A A | | |
| | | | +-----------------------+ | |
| | | | | |
| | | | f_start_file_ind and not P1 | |
| | | +--------------------------------------+ |
| | | F_START_FILE_RS(-) |
| | | |
| | | f_start_file_ind f_start_file_ind |
| | | and P1 and P1 |
| | +----------------------------+ +------------------+
| | F_START_FILE_RS(+) | | F_START_FILE_RS(+)
| | V V
| | o---------------o
| |f_close_file_ind and not P3 | |
| +----------------------------| |
| F_CLOSE_FILE_RS(+,N) | |
| | DATA |
| | TRANSFER |
| f_close_file_ind and not P2 | |-------------+
+------------------------------| | |
F_CLOSE_FILE_RS(-) | |<------------+
o---------------o F_DATA_IND
o---------------o |
| IDLESPEAKER | f_close_file_ind and P3 |
| see (1), Spkr |<--------------------------+
| State Diagram | F_CLOSE_FILE_RS(+,Y)
o---------------o
Predicates:
P1: Decision to send F_START_FILE_RS(+)
P2: Decision to send F_CLOSE_FILE_RS(+)
P3: Decision to become Speaker
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4. Protocol Specification
4.1. Overview
ODETTE-FTP is divided into five operating phases.
Start Session
Start File
Data Transfer
End File
End Session
After the End File phase, an ODETTE-FTP entity may enter a new Start
File phase or terminate the session via the End Session phase.
ODETTE-FTP peers communicate by sending and receiving messages in
Exchange Buffers via the Network Service. Each Exchange Buffer
contains one of the following commands.
SSRM Start Session Ready Message
SSID Start Session
SECD Security Change Direction
AUCH Authentication Challenge
AURP Authentication Response
SFID Start File
SFPA Start File Positive Answer
SFNA Start File Negative Answer
DATA Data
CDT Set Credit
EFID End File
EFPA End File Positive Answer
EFNA End File Negative Answer
ESID End Session
CD Change Direction
EERP End to End Response
NERP Negative End Response
RTR Ready To Receive
The remainder of this section describes the protocol flows. Section
five details the command formats.
4.2. Start Session Phase
The Start Session phase is entered immediately after the network
connection has been established.
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4.2.1. Entity Definition
The ODETTE-FTP entity that took the initiative to establish the
network connection becomes the Initiator. Its peer becomes the
Responder.
4.2.2. Protocol Sequence
The first message must be sent by the Responder.
1. Initiator <-------------SSRM -- Responder Ready Message
-- SSID ------------> Identification
<------------ SSID -- Identification
4.2.3. Secure Authentication
Having exchanged SSIDs, the Initiator may optionally begin an
authentication phase, in which each party proves its identity to the
other.
4.2.4. Protocol Sequence
The first authentication message must be sent by the Initiator.
1. Initiator -- SECD ------------> Responder Change Direction
<------------ AUCH -- Challenge
-- AURP ------------> Response
<------------ SECD -- Change Direction
-- AUCH ------------> Challenge
<------------ AURP -- Response
The Initiator sends a Security Change Direction (SECD) to which the
Responder replies with an Authentication Challenge (AUCH).
The Responder looks up the public certificate that is linked to the
purported identity of the Initiator (located in the SSID). If the
Responder is unable to locate a suitable certificate then
authentication fails. The Responder uses the public key contained in
the certificate to encrypt a random challenge, unique for each
session, for the Initiator. This encrypted challenge is sent as a
[CMS] envelope to the Initiator as part of the AUCH.
The Initiator decrypts the challenge using their private key and
sends the decrypted challenge back to the Responder in the
Authentication Response (AURP).
The Responder checks that the data received in the AURP matches the
random challenge that was sent to the Initiator.
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If the data matches, then the Initiator has authenticated
successfully and the Responder replies with a Security Change
Direction (SECD) beginning the complementary process of verifying the
Responder to the Initiator. If the data does not match, then the
Initiator fails authentication.
4.3. Start File Phase
4.3.1. Entity Definition
The Initiator from the Start Session phase is designated the Speaker
while the Responder becomes the Listener. The roles are reversed by
the Speaker sending a Change Direction command to the Listener.
4.3.2. Protocol Sequence
1. Speaker -- SFID ------------> Listener Start File
<------------ SFPA -- Answer YES
2. Speaker -- SFID ------------> Listener Start File
<------------ SFNA -- Answer NO
Go To 1
Note: The User Monitor should take steps to prevent a loop
situation occurring.
2. Speaker -- CD --------------> Listener Change Direction
Listener <------------ EERP -- Speaker End to End Response
-- RTR -------------> Ready to Receive
<------------ NERP -- Negative End Response
-- RTR -------------> Ready to Receive
<------------ SFID -- Start File
4.3.3. Restart Facilities
The Start File command includes a count allowing the restart of an
interrupted transmission to be negotiated. If restart facilities are
not available, the restart count must be set to zero. The sender
will start with the lowest record count + 1.
4.3.4. Broadcast Facilities
The destination in a Start File command can be specified as follows.
1. An explicitly defined destination.
2. A group destination that allows an intermediate location to
broadcast the Virtual File to multiple destinations.
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The Listener will send a negative answer to the Speaker when the
destination is not known.
4.3.5. Priority
The prioritisation of files for transmission is left to the local
implementation. To allow some flexibility, a change direction
mechanism is available in the End File phase.
4.3.6. End to End Response (EERP)
The End to End Response (EERP) command notifies the originator of a
Virtual File that the Virtual File has been successfully delivered to
its final destination. This allows the originator to perform house
keeping tasks such as deleting copies of the delivered data.
If the originator of the Virtual File requested a signed EERP in the
SFID, the EERP must be signed. Signing allows the originator of the
file to prove that the EERP was generated by the final destination.
If the final destination is unable to sign the EERP, it may send back
an unsigned EERP. It is an implementation issue to allow the
acceptance of an unsigned EERP if a signed EERP is requested.
A Response Command must be sent from the location performing the
final processing or distribution of the data to the originator. The
Response is mandatory and may be sent in the same or in any
subsequent session.
When an intermediate location broadcasts or distributes a Virtual
File, it must receive a Response command from all the locations to
which it forwarded the data before sending its own Response. This
ensures that the Response received by the Virtual File's originator
accounts for all the destination locations. An intermediate location
therefore needs to track the status of files it processes over time.
The requesting of a signed EERP is incompatible with the use of
broadcast facilities because an EERP can be signed by only one
destination. If this scenario occurs, the intermediate broadcast
location may continue and ignore the request for a signed EERP or
send back a NERP.
Example: Point to Point
Location A sends file Ba to location B, which will send an EERP to
location A after it successfully receives the file.
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o----------o o-----------o
| Loc. A |----------- S1 ---------->| Loc. B |
| | | |
| [Ba] |<---------- R2 -----------| [Ba] |
+----------o o-----------o
Key: S - File Transfer
R - Response EERP
[Ba] - File for B from A
Example: Data distribution
Location A sends a Virtual File containing data for distribution
to locations B and C via clearing centres E1 and E2. Clearing
centre E1 must wait for a response from E2 (for file Ba) and
location C before it sends its response, R8, to location A.
Clearing centre E2 can only send response R7 to E1 when location B
acknowledges file Ba with response R6.
o---------o o---------o o---------o o---------o
| Loc. A |-- S1 ->| Loc. E1 |-- S2 ->| Loc. E2 |-- S5 ->| Loc. B |
| | | | | | | |
| [Ba,Ca] |<- R8 --| [Ba,Ca] |<- R7 --| [Ba] |<- R6 --| [Ba] |
o---------o o---------o o---------o o---------o
A |
| | o---------o
| +----- S3 ->| Loc. C |
| | |
+--------- R4 --| [Ca] |
o---------o
Example: Data collection
Locations A and B send files Ca and Cb to clearing centre E1,
which forwards both files to location C in a single Virtual File.
When it receives response R4 from C, clearing centre E1 sends
response R5 to location A and R6 to location B.
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o---------o o---------o o---------o
| Loc. A |-- S1 ->| Loc. E1 |-- S3 ->| Loc. C |
| | | | | |
| [Ca] |<- R5 --| [Ca,Cb] |<- R4 --| [Ca,Cb] |
o---------o o---------o o---------o
A |
o---------o | |
| Loc. B |-- S2 -----+ |
| | |
| [Cb] |<- R6 ---------+
o---------o
4.3.7. Negative End Response (NERP)
In addition to the EERP, which allows control over successful
transmission of a file, a Negative End Response signals that a file
could not be delivered to the final destination or that the final
destination could not process the received file.
It may be created by an intermediate node that could not transmit the
file any further because the next node refuses to accept the file.
The cause of the refusal has to be non-temporary, otherwise the
intermediate node has to try the transmission again.
It may also be created by the final node that is unable to process
the file because of non-recoverable syntax or semantic errors in the
file, or because of the failure of any other processing performed on
the file.
The NERP will be sent back to the originator of the file.
The parameters are equal to the ones of the EERP, but with additional
information about the creator of the NERP and the abort reason.
Where the NERP is created due to a failure to transmit, the abort
reason is taken from the refusal reason that was sent by the node
refusing the file. Because of the NERP, it is possible for the
intermediate node to stop trying to send the non-deliverable file and
to delete the file.
The NERP allows the originator of the file to react to the
unsuccessful transmission or processing, depending on the reason code
and the creator of the NERP.
If the originator of the Virtual File requested a signed EERP in the
SFID, the NERP must be signed. Signing allows the originator of the
file to prove by whom the NERP was generated. If the location
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generating the NERP is unable to sign the NERP, it may send back an
unsigned NERP. It is an implementation issue to allow the acceptance
of an unsigned EERP if a signed NERP is requested.
4.3.8. Ready To Receive Command (RTR)
In order to avoid congestion between two adjacent nodes caused by a
continuous flow of EERPs and NERPs, a Ready To Receive (RTR) command
is provided. The RTR acts as an EERP/NERP acknowledgement for flow
control but has no end-to-end significance.
Speaker -- EERP ------------> Listener End to End Response
<------------- RTR -- Ready to Receive
-- EERP ------------> End to End Response
<------------- RTR -- Ready to Receive
-- NERP ------------> Negative End Response
<------------- RTR -- Ready to Receive
-- SFID ------------> Start File
or
-- CD --------------> Exchange the turn
After sending an EERP or NERP, the Speaker must wait for an RTR
before sending any other commands. The only acceptable commands to
follow are:
EERP
NERP
SFID or CD (if there are no more EERPs or NERPs to be sent)
4.4. Data Transfer Phase
Virtual File data flows from the Speaker to the Listener during the
Data Transfer phase, which is entered after the Start File phase.
4.4.1. Protocol Sequence
To avoid congestion at the protocol level, a flow control mechanism
is provided via the Set Credit (CDT) command.
A Credit limit is negotiated in the Start Session phase; this
represents the number of Data Exchange Buffers that the Speaker may
send before it is obliged to wait for a Credit command from the
Listener.
The available credit is initially set to the negotiated value by the
Start File positive answer, which acts as an implicit Credit command.
The Speaker decreases the available credit count by one for each data
buffer sent to the Listener.
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When the available credit is exhausted, the Speaker must wait for a
Credit command from the Listener; otherwise, a protocol error will
occur and the session will be aborted.
The Listener should endeavour to send the Credit command without
delay to prevent the Speaker blocking.
1. Speaker -- SFID ------------> Listener Start File
<------------ SFPA -- Answer YES
2. If the credit value is set to 2
Speaker -- Data ------------> Listener Start File
-- Data ------------>
<------------- CDT -- Set Credit
-- Data ------------>
-- EFID ------------> End File
4.5. End File Phase
4.5.1. Protocol Sequence
The Speaker notifies the Listener that it has finished sending a
Virtual File by sending an End File (EFID) command. The Listener
replies with a positive or negative End File command and has the
option to request a Change Direction command from the Speaker.
1. Speaker -- EFID ------------> Listener End File
<------------ EFPA -- Answer YES
2. Speaker -- EFID ------------> Listener End File
<------------ EFPA -- Answer YES + CD
-- CD --------------> Change Direction
Listener <------------ EERP -- Speaker End to End Response
-------------- RTR -> Ready to Receive
Listener <------------ NERP -- Speaker Negative End Response
-------------- RTR -> Ready to Receive
Go to Start File Phase
3. Speaker -- EFID ------------> Listener End File
<------------ EFNA -- Answer NO
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4.6. End Session Phase
4.6.1. Protocol Sequence
The Speaker terminates the session by sending an End Session (ESID)
command. The Speaker may only do this if the Listener has just
relinquished its role as speaker.
1. Speaker -- EFID ------------> Listener End File
<------------ EFPA -- Answer YES
-- CD --------------> Change Direction
Listener <------------ ESID -- Speaker End Session
4.7. Problem Handling
Error detection and handling should be done as close as possible to
the problem. This aids problem determination and correction. Each
layer of the reference model is responsible for its own error
handling.
ODETTE-FTP can detect protocol errors by virtue of its state machine
and uses activity timers to detect session hang conditions. These
mechanisms are separate from the End to End controls.
4.7.1. Protocol Errors
If a protocol error occurs, the session will be terminated and
application activity aborted. Both locations enter the IDLE state.
4.7.2. Timers
To protect against application and network hang conditions, ODETTE-
FTP uses activity timers for all situations where a response is
required. The timers and actions to be taken if they expire are
described in Section 9, "Protocol State Machine".
4.7.3. Clearing Centres
The use of clearing centres introduces the possibility of errors
occurring as a result of data processing activities within the
centre. Such errors are not directly related to ODETTE-FTP or the
communication network and are therefore outside the scope of this
specification.
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5. Commands and Formats
ODETTE-FTP entities communicate via Exchange Buffers. The Command
Exchange Buffers are described below. Virtual File data is carried
in Data Exchange Buffers, which are described in Section 7.
5.1. Conventions
5.1.1. Representation Unit
The basic unit of information is an octet, containing 8 bits.
5.1.2. Values and Characters
The ISO 646 IRV 7-bit coded character set [ISO-646], according to
Appendix B, is used to encode constants and strings within Command
Exchange Buffers except where [UTF-8] is explicitly indicated against
a field.
5.2. Commands
A Command Exchange Buffer contains a single command starting at the
beginning of the buffer. Commands and data are never mixed within an
Exchange Buffer. Commands cannot be compressed. Variable-length
parameters may be omitted entirely if not required and the associated
length indicator field set to zero.
Components:
1. Command identifier:
The first octet of an Exchange Buffer is the Command Identifier
and defines the format of the buffer.
2. Parameter(s):
Command parameters are stored in fields within a Command Exchange
Buffer. Where variable-length fields are used, they are preceded
with a header field indicating the length. All values are
required except where explicitly indicated.
5.3. Command Formats
The ODETTE-FTP commands are described below using the following
definitions.
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Position (Pos)
Field offset within the Command Exchange Buffer, relative to a
zero origin.
Field
The name of the field.
Description
A description of the field.
Format
F - A field containing fixed values. All allowable values for
the field are enumerated in the command definition.
V - A field with variable values within a defined range. For
example, the SFIDLRECL field may contain any integer value
between 00000 and 99999.
X(n) - An alphanumeric field of length n octets.
A String contains alphanumeric characters from the following
set:
The numerals: 0 to 9
The upper case letters: A to Z
The following special set: / - . & ( ) space.
Space is not allowed as an embedded character.
9(n) - A numeric field of length n octets.
U(n) - A binary field of length n octets.
Numbers encoded as binary are always unsigned and in
network byte order.
T(n) - An field of length n octets, encoded using [UTF-8].
String and alphanumeric fields are always left justified and right
padded with spaces where needed.
Numeric fields are always right justified and left padded with
zeros where needed.
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Reserved fields should be padded with spaces.
5.3.1. SSRM - Start Session Ready Message
o-------------------------------------------------------------------o
| SSRM Start Session Ready Message |
| |
| Start Session Phase Initiator <---- Responder |
|-------------------------------------------------------------------|
| Pos | Field | Description | Format |
|-----+-----------+---------------------------------------+---------|
| 0 | SSRMCMD | SSRM Command, 'I' | F X(1) |
| 1 | SSRMMSG | Ready Message, 'ODETTE FTP READY ' | F X(17) |
| 18 | SSRMCR | Carriage Return | F X(1) |
o-------------------------------------------------------------------o
SSRMCMD Command Code Character
Value: 'I' SSRM Command identifier.
SSRMMSG Ready Message String(17)
Value: 'ODETTE FTP READY '
SSRMCR Carriage Return Character
Value: Character with hex value '0D' or '8D'.
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5.3.2. SSID - Start Session
o-------------------------------------------------------------------o
| SSID Start Session |
| |
| Start Session Phase Initiator <---> Responder |
|-------------------------------------------------------------------|
| Pos | Field | Description | Format |
|-----+-----------+---------------------------------------+---------|
| 0 | SSIDCMD | SSID Command 'X' | F X(1) |
| 1 | SSIDLEV | Protocol Release Level | F 9(1) |
| 2 | SSIDCODE | Initiator's Identification Code | V X(25) |
| 27 | SSIDPSWD | Initiator's Password | V X(8) |
| 35 | SSIDSDEB | Data Exchange Buffer Size | V 9(5) |
| 40 | SSIDSR | Send / Receive Capabilities (S/R/B) | F X(1) |
| 41 | SSIDCMPR | Buffer Compression Indicator (Y/N) | F X(1) |
| 42 | SSIDREST | Restart Indicator (Y/N) | F X(1) |
| 43 | SSIDSPEC | Special Logic Indicator (Y/N) | F X(1) |
| 44 | SSIDCRED | Credit | V 9(3) |
| 47 | SSIDAUTH | Secure Authentication (Y/N) | F X(1) |
| 48 | SSIDRSV1 | Reserved | F X(4) |
| 52 | SSIDUSER | User Data | V X(8) |
| 60 | SSIDCR | Carriage Return | F X(1) |
o-------------------------------------------------------------------o
SSIDCMD Command Code
Character
Value: 'X' SSID Command identifier.
SSIDLEV Protocol Release Level Numeric(1)
Used to specify the level of the ODETTE-FTP protocol
Value: '1' for Revision 1.2
'2' for Revision 1.3
'4' for Revision 1.4
'5' for Revision 2.0
Future release levels will have higher numbers. The
protocol release level is negotiable, with the lowest level
being selected.
Note: ODETTE File Transfer Protocol 1.3 (RFC 2204)
specifies '1' for the release level, despite adhering
to revision 1.3.
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RFC 5024 ODETTE FTP 2 November 2007
SSIDCODE Initiator's Identification Code String(25)
Format: See Identification Code (Section 5.4)
Uniquely identifies the Initiator (sender) participating in
the ODETTE-FTP session.
It is an application implementation issue to link the
expected [X.509] certificate to the SSIDCODE provided.
SSIDPSWD Initiator's Password String(8)
Key to authenticate the sender. Assigned by bilateral
agreement.
SSIDSDEB Data Exchange Buffer Size Numeric(5)
Minimum: 128
Maximum: 99999
The length, in octets, of the largest Data Exchange Buffer
that can be accepted by the location. The length includes
the command octet but does not include the Stream
Transmission Header.
After negotiation, the smallest size will be selected.
SSIDSR Send / Receive Capabilities Character
Value: 'S' Location can only send files.
'R' Location can only receive files.
'B' Location can both send and receive files.
Sending and receiving will be serialised during the
session, so parallel transmissions will not take place in
the same session.
An error occurs if adjacent locations both specify the send
or receive capability.
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SSIDCMPR Buffer Compression Indicator Character
Value: 'Y' The location can handle OFTP data buffer compression
'N' The location cannot handle OFTP buffer compression
Compression is only used if supported by both locations.
The compression mechanism referred to here applies to each
individual OFTP data buffer. This is different from the
file compression mechanism in OFTP, which involves the
compression of whole files.
SSIDREST Restart Indicator Character
Value: 'Y' The location can handle the restart of a partially
transmitted file.
'N' The location cannot restart a file.
SSIDSPEC Special Logic Indicator Character
Value: 'Y' Location can handle Special Logic
'N' Location cannot handle Special Logic
Special Logic is only used if supported by both locations.
The Special Logic extensions are only useful to access an
X.25 network via an asynchronous entry and are not
supported for TCP/IP connections.
SSIDCRED Credit Numeric(3)
Maximum: 999
The number of consecutive Data Exchange Buffers sent by the
Speaker before it must wait for a Credit (CDT) command from
the Listener.
The credit value is only applied to Data flow in the Data
Transfer phase.
The Speaker's available credit is initialised to SSIDCRED
when it receives a Start File Positive Answer (SFPA)
command from the Listener. It is zeroed by the End File
(EFID) command.
After negotiation, the smallest size must be selected in
the answer of the Responder, otherwise a protocol error
will abort the session.
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Negotiation of the "credit-window-size" parameter.
Window Size m -- SSID ------------>
<------------ SSID -- Window Size n
(n less than or
equal to m)
Note: negotiated value will be "n".
SSIDAUTH Secure Authentication Character
Value: 'Y' The location requires secure authentication. 'N' The
location does not require secure authentication.
Secure authentication is only used if agreed by both
locations.
If the answer of the Responder does not match with the
authentication requirements of the Initiator, then the
Initiator must abort the session.
No negotiation of authentication is allowed.
authentication p -- SSID ------------>
<------------ SSID -- authentication q
p == q -> continue.
p != q -> abort.
SSIDRSV1 Reserved String(4)
This field is reserved for future use.
SSIDUSER User Data String(8)
May be used by ODETTE-FTP in any way. If unused, it should
be initialised to spaces. It is expected that a bilateral
agreement exists as to the meaning of the data.
SSIDCR Carriage Return Character
Value: Character with hex value '0D' or '8D'.
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5.3.3. SFID - Start File
o-------------------------------------------------------------------o
| SFID Start File |
| |
| Start File Phase Speaker ----> Listener |
|-------------------------------------------------------------------|
| Pos | Field | Description | Format |
|-----+-----------+---------------------------------------+---------|
| 0 | SFIDCMD | SFID Command, 'H' | F X(1) |
| 1 | SFIDDSN | Virtual File Dataset Name | V X(26) |
| 27 | SFIDRSV1 | Reserved | F X(3) |
| 30 | SFIDDATE | Virtual File Date stamp, (CCYYMMDD) | V 9(8) |
| 38 | SFIDTIME | Virtual File Time stamp, (HHMMSScccc) | V 9(10) |
| 48 | SFIDUSER | User Data | V X(8) |
| 56 | SFIDDEST | Destination | V X(25) |
| 81 | SFIDORIG | Originator | V X(25) |
| 106 | SFIDFMT | File Format (F/V/U/T) | F X(1) |
| 107 | SFIDLRECL | Maximum Record Size | V 9(5) |
| 112 | SFIDFSIZ | File Size, 1K blocks | V 9(13) |
| 125 | SFIDOSIZ | Original File Size, 1K blocks | V 9(13) |
| 138 | SFIDREST | Restart Position | V 9(17) |
| 155 | SFIDSEC | Security Level | F 9(2) |
| 157 | SFIDCIPH | Cipher suite selection | F 9(2) |
| 159 | SFIDCOMP | File compression algorithm | F 9(1) |
| 160 | SFIDENV | File enveloping format | F 9(1) |
| 161 | SFIDSIGN | Signed EERP request | F X(1) |
| 162 | SFIDDESCL | Virtual File Description length | V 9(3) |
| 165 | SFIDDESC | Virtual File Description | V T(n) |
o-------------------------------------------------------------------o
SFIDCMD Command Code Character
Value: 'H' SFID Command identifier.
SFIDDSN Virtual File Dataset Name String(26)
Dataset name of the Virtual File being transferred,
assigned by bilateral agreement.
No general structure is defined for this attribute.
See Virtual Files - Identification (Section 1.5.2)
SFIDRSV1 Reserved String(3)
This field is reserved for future use.
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SFIDDATE Virtual File Date stamp Numeric(8)
Format: 'CCYYMMDD' 8 decimal digits representing the century,
year, month, and day.
Date stamp assigned by the Virtual File's Originator
indicating when the file was made available for
transmission.
See Virtual Files - Identification (Section 1.5.2)
SFIDTIME Virtual File Time stamp Numeric(10)
Format: 'HHMMSScccc' 10 decimal digits representing hours,
minutes, seconds, and a counter (0001-9999), which gives
higher resolution.
Time stamp assigned by the Virtual File's Originator
indicating when the file was made available for
transmission.
See Virtual Files - Identification (Section 1.5.2)
SFIDUSER User Data String(8)
May be used by ODETTE-FTP in any way. If unused, it should
be initialised to spaces. It is expected that a bilateral
agreement exists as to the meaning of the data.
SFIDDEST Destination String(25)
Format: See Identification Code (Section 5.4)
The Final Recipient of the Virtual File.
This is the location that will look into the Virtual File
content and perform mapping functions. It is also the
location that creates the End to End Response (EERP)
command for the received file.
SFIDORIG Originator String(25)
Format: See Identification Code (Section 5.4)
Originator of the Virtual File.
It is the location that created (mapped) the data for
transmission.
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RFC 5024 ODETTE FTP 2 November 2007
SFIDFMT File Format Character
Value: 'F' Fixed format binary file
'V' Variable format binary file
'U' Unstructured binary file
'T' Text
Virtual File format. Used to calculate the restart
position (Section 1.5.4).
Once a file has been signed, compressed, and/or encrypted,
in file format terms it becomes unstructured, format U.
The record boundaries are no longer discernable until the
file is decrypted, decompressed, and/or verified. SFID
File Format Field in this scenario indicates the format of
the original file, and the transmitted file must be treated
as U format.
SFIDLRECL Maximum Record Size Numeric(5)
Maximum: 99999
Length in octets of the longest logical record that may be
transferred to a location. Only user data is included.
If SFIDFMT is 'T' or 'U', then this attribute must be set
to '00000'.
If SFIDFMT is 'V' and the file is compressed, encrypted, or
signed, then the maximum value of SFIDRECL is '65536'.
SFIDFSIZ Transmitted File Size Numeric(13)
Maximum: 9999999999999
Space in 1K (1024 octet) blocks required at the Originator
location to store the actual Virtual File that is to be
transmitted.
For example, if a file is compressed before sending, then
this is the space required to store the compressed file.
This parameter is intended to provide only a good estimate
of the Virtual File size.
Using 13 digits allows for a maximum file size of
approximately 9.3 PB (petabytes) to be transmitted.
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RFC 5024 ODETTE FTP 2 November 2007
SFIDOSIZ Original File Size Numeric(13)
Maximum: 9999999999999
Space in 1K (1024 octet) blocks required at the Originator
location to store the original before it was signed,
compressed, and/or encrypted.
If no security or compression services have been used,
SFIDOSIZ should contain the same value as SFIDFSIZ.
If the original file size is not known, the value zero
should be used.
This parameter is intended to provide only a good estimate
of the original file size.
The sequence of events in file exchange are:
(a) raw data file ready to be sent
SFIDOSIZ = Original File Size
(b) signing/compression/encryption
(c) transmission
SFIDFSIZ = Transmitted File Size
(d) decryption/decompression/verification
(e) received raw data file for in-house applications
SFIDOSIZ = Original File Size
The Transmitted File Size at (c) indicates to the receiver
how much storage space is needed to receive the file.
The Original File Size at (e) indicates to the in-house
application how much storage space is needed to process the
file.
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SFIDREST Restart Position Numeric(17)
Maximum: 99999999999999999
Virtual File restart position.
The count represents the:
- Record Number if SSIDFMT is 'F' or 'V'.
- File offset in 1K (1024 octet) blocks if SFIDFMT is
'U' or 'T'.
The count will express the transmitted user data (i.e.,
before ODETTE-FTP buffer compression, header not included).
After negotiation between adjacent locations,
retransmission will start at the lowest value.
Once a file has been signed, compressed, and/or encrypted,
in file format terms, it has become unstructured, like
format U. The file should be treated as format U for the
purposes of restart, regardless of the actual value in
SFIDFMT.
SFIDSEC Security Level Numeric(2)
Value: '00' No security services
'01' Encrypted
'02' Signed
'03' Encrypted and signed
Indicates whether the file has been signed and/or encrypted
before transmission. (See Section 6.2.)
SFIDCIPH Cipher suite selection Numeric(2)
Value: '00' No security services
'01' See Section 10.2
Indicates the cipher suite used to sign and/or encrypt the
file and also to indicate the cipher suite that should be
used when a signed EERP or NERP is requested.
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RFC 5024 ODETTE FTP 2 November 2007
SFIDCOMP File compression algorithm Numeric(1)
Value: '0' No compression
'1' Compressed with [ZLIB] algorithm
Indicates the algorithm used to compress the file.
(See Section 6.4.)
SFIDENV File enveloping format Numeric(1)
Value: '0' No envelope
'1' File is enveloped using [CMS]
Indicates the enveloping format used in the file.
If the file is encrypted/signed/compressed or is an
enveloped file for the exchange and revocation of
certificates, this field must be set accordingly.
SFIDSIGN Signed EERP request Character
Value: 'Y' The EERP returned in acknowledgement of the file
must be signed
'N' The EERP must not be signed
Requests whether the EERP returned for the file must be
signed.
SFIDDESCL Virtual File Description length Numeric(3)
Length in octets of the field SFIDDESC.
A value of 0 indicates that no description is present.
SFIDDESC Virtual File Description [UTF-8](n)
May be used by ODETTE-FTP in any way. If not used,
SFIDDESCL should be set to zero.
No general structure is defined for this attribute, but it
is expected that a bilateral agreement exists as to the
meaning of the data.
It is encoded using [UTF-8] to support a range of national
languages.
Maximum length of the encoded value is 999 octets.
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RFC 5024 ODETTE FTP 2 November 2007
5.3.4. SFPA - Start File Positive Answer
o-------------------------------------------------------------------o
| SFPA Start File Positive Answer |
| |
| Start File Phase Speaker <---- Listener |
|-------------------------------------------------------------------|
| Pos | Field | Description | Format |
|-----+-----------+---------------------------------------+---------|
| 0 | SFPACMD | SFPA Command, '2' | F X(1) |
| 1 | SFPAACNT | Answer Count | V 9(17) |
o-------------------------------------------------------------------o
SFPACMD Command Code Character
Value: '2' SFPA Command identifier.
SFPAACNT Answer Count Numeric(17)
The Listener must enter a count lower than or equal to the
restart count specified by the Speaker in the Start File
(SFID) command. The count expresses the received user
data. If restart facilities are not available, a count of
zero must be specified.
5.3.5. SFNA - Start File Negative Answer
o-------------------------------------------------------------------o
| SFNA Start File Negative Answer |
| |
| Start File Phase Speaker <---- Listener |
|-------------------------------------------------------------------|
| Pos | Field | Description | Format |
|-----+-----------+---------------------------------------+---------|
| 0 | SFNACMD | SFNA Command, '3' | F X(1) |
| 1 | SFNAREAS | Answer Reason | F 9(2) |
| 3 | SFNARRTR | Retry Indicator, (Y/N) | F X(1) |
| 4 | SFNAREASL | Answer Reason Text Length | V 9(3) |
| 7 | SFNAREAST | Answer Reason Text | V T(n) |
o-------------------------------------------------------------------o
SFNACMD Command Code Character
Value: '3' SFNA Command identifier.
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RFC 5024 ODETTE FTP 2 November 2007
SFNAREAS Answer Reason Numeric(2)
Value: '01' Invalid filename.
'02' Invalid destination.
'03' Invalid origin.
'04' Storage record format not supported.
'05' Maximum record length not supported.
'06' File size is too big.
'10' Invalid record count.
'11' Invalid byte count.
'12' Access method failure.
'13' Duplicate file.
'14' File direction refused.
'15' Cipher suite not supported.
'16' Encrypted file not allowed.
'17' Unencrypted file not allowed.
'18' Compression not allowed.
'19' Signed file not allowed.
'20' Unsigned file not allowed.
'99' Unspecified reason.
Reason why transmission cannot proceed.
SFNARRTR Retry Indicator Character
Value: 'N' Transmission should not be retried.
'Y' The transmission may be retried later.
This parameter is used to advise the Speaker if it should
retry at a later time due to a temporary condition at the
Listener site, such as a lack of storage space. It should
be used in conjunction with the Answer Reason code
(SFNAREAS).
An invalid file name error code may be the consequence of a
problem in the mapping of the Virtual File on to a real
file. Such problems cannot always be resolved immediately.
It is therefore recommended that when an SFNA with Retry =
Y is received the User Monitor attempts to retransmit the
relevant file in a subsequent session.
SFNAREASL Answer Reason Text Length Numeric(3)
Length in octets of the field SFNAREAST.
0 indicates that no SFNAREAST field follows.
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RFC 5024 ODETTE FTP 2 November 2007
SFNAREAST Answer Reason Text [UTF-8](n)
Reason why transmission cannot proceed in plain text.
It is encoded using [UTF-8].
Maximum length of the encoded reason is 999 octets.
No general structure is defined for this attribute.
5.3.6. DATA - Data Exchange Buffer
o-------------------------------------------------------------------o
| DATA Data Exchange Buffer |
| |
| Data Transfer Phase Speaker ----> Listener |
|-------------------------------------------------------------------|
| Pos | Field | Description | Format |
|-----+-----------+---------------------------------------+---------|
| 0 | DATACMD | DATA Command, 'D' | F X(1) |
| 1 | DATABUF | Data Exchange Buffer payload | V U(n) |
o-------------------------------------------------------------------o
DATACMD Command Code Character
Value: 'D' DATA Command identifier.
DATABUF Data Exchange Buffer payload Binary(n)
Variable-length buffer containing the data payload. The
Data Exchange Buffer is described in Section 7.
5.3.7. CDT - Set Credit
o-------------------------------------------------------------------o
| CDT Set Credit |
| |
| Data Transfer Phase Speaker <---- Listener |
|-------------------------------------------------------------------|
| Pos | Field | Description | Format |
|-----+-----------+---------------------------------------+---------|
| 0 | CDTCMD | CDT Command, 'C' | F X(1) |
| 1 | CDTRSV1 | Reserved | F X(2) |
o-------------------------------------------------------------------o
CDTCMD Command Code Character
Value: 'C' CDT Command identifier.
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RFC 5024 ODETTE FTP 2 November 2007
CDTRSV1 Reserved String(2)
This field is reserved for future use.
5.3.8. EFID - End File
o-------------------------------------------------------------------o
| EFID End File |
| |
| End File Phase Speaker ----> Listener |
|-------------------------------------------------------------------|
| Pos | Field | Description | Format |
|-----+-----------+---------------------------------------+---------|
| 0 | EFIDCMD | EFID Command, 'T' | F X(1) |
| 1 | EFIDRCNT | Record Count | V 9(17) |
| 18 | EFIDUCNT | Unit Count | V 9(17) |
o-------------------------------------------------------------------o
EFIDCMD Command Code Character
Value: 'T' EFID Command identifier.
EFIDRCNT Record Count Numeric(17)
Maximum: 99999999999999999
For SSIDFMT 'F' or 'V', the exact record count.
For SSIDFMT 'U' or 'T', zeros.
The count will express the real size of the file (before
buffer compression, header not included). The total count
is always used, even during restart processing.
EFIDUCNT Unit Count Numeric(17)
Maximum: 99999999999999999
Exact number of units (octets) transmitted.
The count will express the real size of the file. The
total count is always used, even during restart processing.
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5.3.9. EFPA - End File Positive Answer
o-------------------------------------------------------------------o
| EFPA End File Positive Answer |
| |
| End File Phase Speaker <---- Listener |
|-------------------------------------------------------------------|
| Pos | Field | Description | Format |
|-----+-----------+---------------------------------------+---------|
| 0 | EFPACMD | EFPA Command, '4' | F X(1) |
| 1 | EFPACD | Change Direction Indicator, (Y/N) | F X(1) |
o-------------------------------------------------------------------o
EFPACMD Command Code Character
Value: '4' EFPA Command identifier.
EFPACD Change Direction Indicator Character
Value: 'N' Change direction not requested.
'Y' Change direction requested.
This parameter allows the Listener to request a Change
Direction (CD) command from the Speaker.
5.3.10. EFNA - End File Negative Answer
o-------------------------------------------------------------------o
| EFNA End File Negative Answer |
| |
| End File Phase Speaker <---- Listener |
|-------------------------------------------------------------------|
| Pos | Field | Description | Format |
|-----+-----------+---------------------------------------+---------|
| 0 | EFNACMD | EFNA Command, '5' | F X(1) |
| 1 | EFNAREAS | Answer Reason | F 9(2) |
| 3 | EFNAREASL | Answer Reason Text Length | V 9(3) |
| 6 | EFNAREAST | Answer Reason Text | V T(n) |
o-------------------------------------------------------------------o
EFNACMD Command Code Character
Value: '5' EFNA Command identifier.
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EFNAREAS Answer Reason Numeric(2)
Value: '01' Invalid filename.
'02' Invalid destination.
'03' Invalid origin.
'04' Storage record format not supported.
'05' Maximum record length not supported.
'06' File size is too big.
'10' Invalid record count.
'11' Invalid byte count.
'12' Access method failure.
'13' Duplicate file.
'14' File direction refused.
'15' Cipher suite not supported.
'16' Encrypted file not allowed.
'17' Unencrypted file not allowed.
'18' Compression not allowed.
'19' Signed file not allowed.
'20' Unsigned file not allowed.
'21' Invalid file signature.
'22' File decryption failure.
'23' File decompression failure.
'99' Unspecified reason.
Reason why transmission failed.
EFNAREASL Answer Reason Text Length Numeric(3)
Length in octets of the field EFNAREAST.
0 indicates that no EFNAREAST field follows.
EFNAREAST Answer Reason Text [UTF-8](n)
Reason why transmission failed in plain text.
It is encoded using [UTF-8].
Maximum length of the encoded reason is 999 octets.
No general structure is defined for this attribute.
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RFC 5024 ODETTE FTP 2 November 2007
5.3.11. ESID - End Session
o-------------------------------------------------------------------o
| ESID End Session |
| |
| End Session Phase Speaker ----> Listener |
|-------------------------------------------------------------------|
| Pos | Field | Description | Format |
|-----+-----------+---------------------------------------+---------|
| 0 | ESIDCMD | ESID Command, 'F' | F X(1) |
| 1 | ESIDREAS | Reason Code | F 9(2) |
| 3 | ESIDREASL | Reason Text Length | V 9(3) |
| 6 | ESIDREAST | Reason Text | V T(n) |
| | ESIDCR | Carriage Return | F X(1) |
o-------------------------------------------------------------------o
ESIDCMD Command Code Character
Value: 'F' ESID Command identifier.
ESIDREAS Reason Code Numeric(2)
Value: '00' Normal session termination
'01' Command not recognised
An Exchange Buffer contains an invalid command code
(1st octet of the buffer).
'02' Protocol violation
An Exchange Buffer contains an invalid command for
the current state of the receiver.
'03' User code not known
A Start Session (SSID) command contains an unknown or
invalid Identification Code.
'04' Invalid password
A Start Session (SSID) command contained an invalid
password.
'05' Local site emergency close down
The local site has entered an emergency close down
mode. Communications are being forcibly terminated.
Fri |
