1080 lines
52 KiB
HTML
Executable File
1080 lines
52 KiB
HTML
Executable File
<HTML>
|
|
<!-- $Id$ -->
|
|
<HEAD>
|
|
<TITLE>EMSI/IEMSI Protocol Definitions.</TITLE>
|
|
</HEAD>
|
|
|
|
<!-- Background white, links blue (unvisited), navy (visited), red (active) -->
|
|
<BODY
|
|
BGCOLOR="#FFFFFF"
|
|
TEXT="#000000"
|
|
LINK="#0000FF"
|
|
VLINK="#000080"
|
|
ALINK="#FF0000"
|
|
>
|
|
<PRE>
|
|
Document: FSC-0056
|
|
Version: 001
|
|
Date: 03-May-1991
|
|
|
|
|
|
|
|
|
|
|
|
EMSI/IEMSI Protocol Definitions
|
|
Joaquim H. Homrighausen
|
|
May 3, 1991
|
|
|
|
|
|
|
|
|
|
Status of this document:
|
|
|
|
This FSC suggests a proposed protocol for the FidoNet(r) community,
|
|
and requests discussion and suggestions for improvements.
|
|
Distribution of this document is subject to the restrictions
|
|
specified on the next page.
|
|
|
|
Fido and FidoNet are registered marks of Tom Jennings and Fido
|
|
Software.
|
|
|
|
|
|
|
|
|
|
(Also known as EMSC-001; Electronic Mail Standards Document #001)
|
|
---------------------------------------------------------------------
|
|
Copyright 1989-1991 Joaquim H. Homrighausen. All rights reserved.
|
|
---------------------------------------------------------------------
|
|
|
|
|
|
Notice
|
|
=====================================================================
|
|
This document obsoletes EMSI_003 and any previous document describing
|
|
the EMSI, UZAP, and/or IEMSI handshake protocol. I apologize for the
|
|
lack of proper state charts. I am currently under a fairly heavy
|
|
work-load and thought it would be better to release something half-
|
|
decent than not to release anything at all.
|
|
|
|
Restrictions
|
|
=====================================================================
|
|
EMSI/IEMSI may be used by any developer as long as these
|
|
specifications are followed exactly. The IEMSI and EMSI specifications
|
|
may be implemented independently of each other.
|
|
|
|
EMSI/IEMSI may be used free-of-charge by any developer for any
|
|
purpose, commercially or otherwise. In creating EMSI/IEMSI, we are
|
|
taking the first step towards developing a clear protocol definition
|
|
for state-of-the-art E-Mail systems to follow.
|
|
|
|
This document and its NOTES file (EMSI.NOT) may be freely copied and
|
|
distributed, but must NEVER be distributed in a modified form. If you
|
|
have an enhancement request, please contact the author of this
|
|
document; do not change it yourself.
|
|
|
|
Permission is hereby granted to the FTSC (Fidonet Technical Standards
|
|
Committee) and other technical organisations to republish this
|
|
document in its entirety. Librarians may change the title page and
|
|
page headers to match their library format as long as all copyrights
|
|
and body text remain unaltered. The original document name and source
|
|
(EMSC) must be mentioned in any republished versions of this
|
|
document.
|
|
|
|
No organization, company, person, or other being may impose any fees
|
|
for any reason for providing this document. This document may not be
|
|
sold or otherwise transferred for personal or company gain under any
|
|
circumstances.
|
|
|
|
Layout
|
|
=====================================================================
|
|
This document consists of four major parts; A short introduction and
|
|
explanation of the EMSI/IEMSI handshake protocol, the EMSI
|
|
definitions, the IEMSI definitions, and finally various notes and
|
|
credits.
|
|
|
|
|
|
PART I
|
|
|
|
Introduction
|
|
=====================================================================
|
|
The EMSI/IEMSI handshake protocol allows for maximum flexibility in
|
|
E-Mail session start-up and control. The YooHoo (FTS-6) standard,
|
|
designed by Wynn Wagner III, was a good idea, but did not allow
|
|
sufficient room for growth and cannot be used in 7-bit environments.
|
|
EMSI/IEMSI should provide for virtually unlimited growth and
|
|
expansion of its own scope. By providing variable-length packets,
|
|
EMSI/IEMSI is capable of being as simple or as complex as necessary
|
|
and entirely backwards compatible when new features and/or protocols
|
|
are added.
|
|
|
|
All EMSI/IEMSI packets and sequences consists of 7-bit printable
|
|
ASCII characters. This format allows us to establish a universal
|
|
handshake between "PCs" and "mainframes" alike. The more complicated
|
|
the computer system, the more restrictions affect its I/O; there are
|
|
many I/O channels that cannot transmit control characters such as XON
|
|
and XOFF; for this, we have created a universal handshake protocol
|
|
that uses all printable characters.
|
|
|
|
EMSI/IEMSI does allow control and 8-bit ASCII characters to be
|
|
transmitted. This is, however, accomplished by escaping the data
|
|
and converting it to 7-bit printable ASCII characters.
|
|
|
|
Data layer
|
|
=====================================================================
|
|
EMSI/IEMSI is a protocol based on multi-character sequences rather
|
|
than single character flow control. There are several advantages of
|
|
using several characters rather than just one, but there is also a
|
|
drawback. On very poor-quality telephone lines, EMSI will most likely
|
|
require several retransmissions of packets since line noise usually
|
|
come in bursts. That aside, there is little advantage in using a
|
|
protocol based on single characters.
|
|
|
|
All EMSI/IEMSI sequences are terminated by a single <CR> unless
|
|
otherwise specified. This is necessary to force some data collection
|
|
equipment to flush their buffers. Appending <CR> to EMSI/IEMSI
|
|
sequences in a FidoNet environment is a delicate matter and it is
|
|
important that you follow the notes regarding this.
|
|
|
|
Note regarding file requests
|
|
---------------------------------------------------------------------
|
|
The file request concept mentioned in the EMSI document refers to
|
|
WaZOO style file requests as specified in FTS-6. No other file
|
|
request mechanism is supported in the EMSI specifications.
|
|
|
|
|
|
Separator usage
|
|
---------------------------------------------------------------------
|
|
To designate the fields within the EMSI/IEMSI packets and retain
|
|
complete transparency, both start and stop characters are used.
|
|
|
|
The ASCII1 type is used for all fields within the packet. This uses
|
|
the brace characters to delimit the fields. The '{' (ASCII 123)
|
|
character is the start byte and '}' (ASCII 125) is the stop byte.
|
|
If a stop byte is used as literal data within a field, it must be
|
|
transmitted twice. The end of a field is designated by a stop byte
|
|
that is not followed by another identical stop byte.
|
|
|
|
The ASCII2 fields are delimited in exactly the same way, but use the
|
|
square brackets as delimiters. The '[' (ASCII 91) is the start byte
|
|
and ']' (ASCII 93) is the stop byte. ASCII2 is used to delimit data
|
|
within the ASCII1 extra_field information.
|
|
|
|
7-bit data restriction
|
|
---------------------------------------------------------------------
|
|
It is the developer's responsibility to ensure that the software
|
|
generates EMSI/IEMSI packets and sequences containing only 7-bit
|
|
(00H through 7eH) printable ASCII characters.
|
|
|
|
It is recommended that all EMSI/IEMSI implementations strip the high-
|
|
order bit of all received characters prior to processing the packet/
|
|
sequence and prior to calculating CRC values.
|
|
|
|
CRC values
|
|
---------------------------------------------------------------------
|
|
The polynomial used to calculate a 16-bit CRC is the same polynomial
|
|
used in the Xmodem file transfer protocol. The polynomial used to
|
|
calculate a 32-bit CRC is the same polynomial used in the Zmodem file
|
|
transfer protocol.
|
|
|
|
Binary values
|
|
---------------------------------------------------------------------
|
|
Since the EMSI environment specifies only 7-bit printable ASCII
|
|
characters to be used, binary values, such as CRC and length
|
|
descriptors are expressed as a four character hexadecimal string. The
|
|
only exception to this is a 32-bit CRC value which is expressed as an
|
|
eight character hexadecimal string.
|
|
|
|
The application must treat them case insensitive, eg. ffaa should be
|
|
treated identical to FFAA.
|
|
|
|
|
|
Handling 8-bit data
|
|
---------------------------------------------------------------------
|
|
Although EMSI only uses 7-bit printable ASCII characters, there is an
|
|
escape mechanism that allows systems to transmit control and 8-bit
|
|
ASCII characters without the requirement of an 8-bit data link. The
|
|
escape character is a backslash character ('\') and is followed by two
|
|
characters in hexadecimal notation. Eg. "\80" is the ASCII character
|
|
128. To insert an actual backslash character, two backslashes are used
|
|
("\\"), or a backslash followed by the hexadecimal code for a
|
|
backslash, eg. "\5c".
|
|
|
|
The hexadecimal code following a backslash MUST always be two
|
|
characters, ie. to insert ASCII 15 (hexadecimail 'f'), the result
|
|
would be "0f". All hexadecimal sequences must be treated case
|
|
insensitively.
|
|
|
|
|
|
PART II - Electronic Mail Standard Idenfitication
|
|
|
|
Connecting two EMSI capable systems
|
|
=====================================================================
|
|
This assumes that the two systems are connected and that no data
|
|
has been transmitted by the Caller.
|
|
|
|
It should be mentioned that sending/monitoring for the "YooHoo",
|
|
"TSYNC", and other protocol start characters is optional and not
|
|
required for a strict EMSI implementation.
|
|
|
|
STEP 1, EMSI INIT
|
|
|
|
Calling system Answering system
|
|
+-+-------------------------------+----------------------------------+
|
|
:1: Send <CR> until ANY character : Send EMSI_REQ and possible :
|
|
: : is received. : banner, etc. :
|
|
+-+-------------------------------+----------------------------------+
|
|
:2: Receive banner, etc. Monitor : Monitor line for the EMSI_INQ :
|
|
: : line for the EMSI_REQ : sequence and if received, :
|
|
: : sequence and if received, : attempt to handshake immediately.:
|
|
: : transmit EMSI_INQ and attempt : :
|
|
: : to handshake immediately. : :
|
|
+-+-------------------------------+----------------------------------+
|
|
:3: No EMSI_REQ sequence received,: Monitor line for EMSI_INQ and :
|
|
: : send EMSI_INQ twice followed : possible other protocol start :
|
|
: : by possible other protocol : characters and if received, :
|
|
: : start characters. : attempt to handshake immediately.:
|
|
: : : :
|
|
: : Transmit <CR> : Go to step 3. :
|
|
+-+-------------------------------+----------------------------------+
|
|
:4: If EMSI_REQ sequence received,:
|
|
: : send EMSI_INQ and attempt to :
|
|
: : handshake immediately, :
|
|
: : otherwise repeat step 3. :
|
|
+-+-------------------------------+
|
|
|
|
In steps 1 and 2, both the Calling and Answering system terminate all
|
|
sequences with <CR>. In step 3, the Calling system does not terminate
|
|
sequences with <CR> as it is explicitly transmitted after possible
|
|
protocol start characters. In step 4, the Calling system once again
|
|
terminate all sequences with a <CR>.
|
|
|
|
|
|
STEP 2A, RECEIVE EMSI HANDSHAKE
|
|
|
|
At this point, all sequences are terminated with a <CR>.
|
|
|
|
+-+------------------------------------------------------------------+
|
|
:1: Tries=0, T1=20 seconds, T2=60 seconds :
|
|
+-+------------------------------------------------------------------+
|
|
:2: Increment Tries :
|
|
: : :
|
|
: : Tries>6? Terminate, and report failure. :
|
|
: +------------------------------------------------------------------+
|
|
: : Are we answering system? Transmit EMSI_REQ, go to step 3. :
|
|
: +------------------------------------------------------------------+
|
|
: : Tries>1? Transmit EMSI_NAK, go to step 3. :
|
|
: +------------------------------------------------------------------+
|
|
: : Go to step 4. :
|
|
+-+------------------------------------------------------------------+
|
|
:3: T1=20 seconds :
|
|
+-+------------------------------------------------------------------+
|
|
:4: Wait for EMSI sequence until EMSI_HBT or EMSI_DAT or any of the :
|
|
: : timers have expired. :
|
|
: : :
|
|
: : If T2 has expired, terminate call and report failure. :
|
|
: +------------------------------------------------------------------+
|
|
: : If T1 has expired, go to step 2. :
|
|
: +------------------------------------------------------------------+
|
|
: : If EMSI_HBT received, go to step 3. :
|
|
: +------------------------------------------------------------------+
|
|
: : If EMSI_DAT received, go to step 5. :
|
|
: +------------------------------------------------------------------+
|
|
: : Go to step 4. :
|
|
+-+------------------------------------------------------------------+
|
|
:5: Receive EMSI_DAT packet :
|
|
: +------------------------------------------------------------------+
|
|
: : Packet received OK? Transmit EMSI_ACK twice, and :
|
|
: : go to step 6. :
|
|
: +------------------------------------------------------------------+
|
|
: : Go to step 2. :
|
|
+-+------------------------------------------------------------------+
|
|
:6: Received EMSI_DAT packet OK, exit. :
|
|
+-+------------------------------------------------------------------+
|
|
|
|
All processing of the information in the EMSI_DAT packet must be done
|
|
after transmitting EMSI_ACK twice to the remote system. It is
|
|
recommended that an EMSI_HBT sequence is issued once every seven
|
|
seconds while such processing is taking place to avoid unnecessary
|
|
handshake collissions. Emitting EMSI_HBT should only be done when
|
|
it is obvious that the remote system is waiting for the second phase
|
|
of the EMSI handshake to take place.
|
|
|
|
|
|
|
|
STEP 2B, TRANSMIT EMSI HANDSHAKE
|
|
|
|
At this point, all sequences are terminated with a <CR>.
|
|
|
|
+-+------------------------------------------------------------------+
|
|
:1: Tries=0, T1=60 seconds :
|
|
+-+------------------------------------------------------------------+
|
|
:2: Transmit EMSI_DAT packet and increment Tries :
|
|
: : :
|
|
: +------------------------------------------------------------------+
|
|
: : Tries>6? Terminate, and report failure. :
|
|
: +------------------------------------------------------------------+
|
|
: : Go to step 3. :
|
|
+-+------------------------------------------------------------------+
|
|
:3: T2=20 seconds :
|
|
+-+------------------------------------------------------------------+
|
|
:4: Wait for EMSI sequence until T1 has expired :
|
|
: : :
|
|
: : If T1 has expired, terminate call and report failure. :
|
|
: +------------------------------------------------------------------+
|
|
: : If T2 has expired, go to step 2. :
|
|
: +------------------------------------------------------------------+
|
|
: : If EMSI_REQ received, go to step 4. :
|
|
: +------------------------------------------------------------------+
|
|
: : If EMSI_ACK received, go to step 5. :
|
|
: +------------------------------------------------------------------+
|
|
: : If any other sequence received, go to step 2. : :
|
|
+-+------------------------------------------------------------------+
|
|
:5: Received EMSI_ACK, exit. :
|
|
+-+------------------------------------------------------------------+
|
|
|
|
|
|
EMSI packet and sequence definitions
|
|
=====================================================================
|
|
|
|
=====================================================================
|
|
EMSI Inquiry **EMSI_INQ<crc16><CR>
|
|
---------------------------------------------------------------------
|
|
EMSI Inquiry is transmitted by the calling system to identify it as
|
|
EMSI capable. If an EMSI_REQ sequence is received in response, it is
|
|
safe to assume the answering system to be EMSI capable.
|
|
|
|
=====================================================================
|
|
EMSI Request **EMSI_REQ<crc16><CR>
|
|
---------------------------------------------------------------------
|
|
EMSI Request is transmitted by the answering system in response to an
|
|
EMSI Inquiry sequence. It should also be transmitted prior to or
|
|
immediately following the answering system has identified itself by
|
|
transmitting its program name and/or banner. If the calling system
|
|
receives an EMSI Request sequence, it can safely assume that the
|
|
answering system is EMSI capable.
|
|
|
|
=====================================================================
|
|
EMSI Client **EMSI_CLI<crc16><CR>
|
|
---------------------------------------------------------------------
|
|
EMSI Client is used by terminal emulation software to force a mailer
|
|
front-end to bypass any unnecessary mail session negotiation and
|
|
treat the call as an incoming human caller. The EMSI_CLI sequence may
|
|
not be issued by any software attempting to establish a mail session
|
|
between two systems and must only be acted upon by an answering
|
|
system.
|
|
|
|
=====================================================================
|
|
EMSI Heartbeat **EMSI_HBT<crc16><CR>
|
|
---------------------------------------------------------------------
|
|
EMSI Heartbeat is used to prevent unnecessary timeouts from occurring
|
|
while attempting to handshake. It is most commonly used when the
|
|
answering system turns around to transmit its EMSI_DAT packet. It is
|
|
quite normal that any of the timers of the calling system (which at
|
|
this stage is waiting for an EMSI_DAT packet) expires while the
|
|
answering system is processing the recently received EMSI_DAT packet.
|
|
|
|
=====================================================================
|
|
EMSI Data **EMSI_DAT<len16><data_pkt><crc16><CR>
|
|
---------------------------------------------------------------------
|
|
EMSI Data is transmitted by both the calling and answering system at
|
|
the appropriate time to exchange system information. Following the
|
|
header is a four byte number representing the length of <data_pkt>
|
|
excluding the CRC and terminating <CR>.
|
|
|
|
The EMSI_DAT packet is a variable length packet. Since this is a
|
|
synchronous protocol, the inbound data buffer should be purged
|
|
between transmission of the <data_pkt> and <crc16> fields to prevent
|
|
accidental EMSI_NAK sequences, etc.
|
|
|
|
|
|
=====================================================================
|
|
EMSI ACK **EMSI_ACK<crc16><CR>
|
|
---------------------------------------------------------------------
|
|
EMSI ACK is transmitted by either system as a positive
|
|
acknowledgement of the valid receipt of a EMSI_DAT packet. This should
|
|
only be used as a response to EMSI_DAT and not any other packet.
|
|
Redundant EMSI_ACK sequences should be ignored.
|
|
|
|
=====================================================================
|
|
EMSI NAK **EMSI_NAK<crc16><CR>
|
|
---------------------------------------------------------------------
|
|
EMSI NAK is transmitted by either system as a negative
|
|
acknowledgement of the valid receipt of a EMSI_DAT packet. This
|
|
should only be used as a response to EMSI_DAT and not any other
|
|
packet. Redundant EMSI_NAK packets should be ignored.
|
|
|
|
The EMSI_DAT packet
|
|
=====================================================================
|
|
The EMSI_DAT packet is the core of an EMSI negotiated session. It
|
|
contains information vital to the mail session. The following pseudo
|
|
structure shows the layout of the EMSI_DAT packet.
|
|
|
|
EMSI_DAT
|
|
fingerprint, "EMSI"
|
|
system_address_list,
|
|
password,
|
|
link_codes,
|
|
compatibility_codes,
|
|
mailer_product_code,
|
|
mailer_name,
|
|
mailer_version,
|
|
mailer_serial_number: ASCII1;
|
|
extra_field_1,
|
|
..
|
|
..
|
|
extra_field_n: EMSI_addon; (optional fields)
|
|
end;
|
|
|
|
The EMSI_addon structure is defined as follows:
|
|
|
|
EMSI_addon
|
|
product_ID,
|
|
specific_data: ASCII1;
|
|
end;
|
|
|
|
|
|
Following is an example of the actual data transmitted as an EMSI_DAT
|
|
packet:
|
|
|
|
{EMSI}{2:270/17}{}{8N1,PUA}{ZAP,ZMO,ARC,XMA}{44}{AirMail}{0.10}
|
|
{Beta-2}{IDENT}{[Advanced Engineering S.A.R.L.][Luxembourg]
|
|
[Joaquim Homrighausen][-Unpublished-][9600][MO,XA,HST,V32B,V42B]}
|
|
|
|
EMSI_DAT field definitions
|
|
---------------------------------------------------------------------
|
|
|
|
=====================================================================
|
|
Fingerprint EMSI
|
|
---------------------------------------------------------------------
|
|
The constant "EMSI". There is no need for a revision level since this
|
|
basic format cannot change and remain backward compatible.
|
|
|
|
=====================================================================
|
|
System address list
|
|
---------------------------------------------------------------------
|
|
The system address list is a list of system-specific identifiers for
|
|
the E-Mail system separated by spaces.
|
|
|
|
For FidoNet-technology based networks, it is required that
|
|
Zone:Net/Node be presented, and .Point be omitted if zero. Zone and
|
|
Net must not be zero.
|
|
|
|
In other networks, an address such as "jhom@csource.oz.au" should be
|
|
considered valid.
|
|
|
|
=====================================================================
|
|
Password
|
|
---------------------------------------------------------------------
|
|
For systems using a session level password, it would be passed in
|
|
this field. Note that the same password is used for all presented
|
|
addresses and that it must be treated case insensitive.
|
|
|
|
=====================================================================
|
|
Link codes
|
|
---------------------------------------------------------------------
|
|
Link codes is a string of flags that specify desired connect
|
|
conditions. These codes are separated by commas. New codes may be
|
|
added with prior approval from the author of this document.
|
|
|
|
Calling system/answering system options:
|
|
|
|
8N1,
|
|
7E1,
|
|
7O2,
|
|
etc. Communication parameters.
|
|
|
|
Calling system options:
|
|
|
|
PUA Pickup mail for all presented addresses.
|
|
PUP Pickup mail for primary address only.
|
|
NPU No mail pickup desired.
|
|
|
|
|
|
Answering system options:
|
|
|
|
HAT Hold ALL traffic.
|
|
HXT Hold compressed mail traffic.
|
|
HRQ Hold file requests (not processed at this time).
|
|
|
|
=====================================================================
|
|
Compatibility codes
|
|
---------------------------------------------------------------------
|
|
Compatibility codes is a string of flags that specifies the
|
|
capabilities and enabled features of the mailer. These codes are
|
|
separated by commas. New codes may be added with prior approval from
|
|
the author of this document.
|
|
|
|
The calling system must list supported protocols first and descending
|
|
order of preference (the most desirable protocol should be listed
|
|
first). The answering system should only present one protocol and it
|
|
should be the first item in the compatibility_codes field.
|
|
|
|
Protocols
|
|
-----------------------------------------------------------------
|
|
DZA* DirectZAP (Zmodem variant).
|
|
ZAP ZedZap (Zmodem variant).
|
|
ZMO** Zmodem w/1,024 byte data packets.
|
|
JAN Janus.
|
|
KER Kermit.
|
|
|
|
Other codes
|
|
-----------------------------------------------------------------
|
|
NCP No compatible protocols (failure).
|
|
NRQ No file requests accepted by this system.
|
|
ARC ARCmail 0.60-capable, as defined by the FTSC.
|
|
XMA Supports other forms of compressed mail.
|
|
FNC Filename conversion. This indicates that any transmitted
|
|
files must follow the MS-DOS restrictions of an eight
|
|
character file name followed by a three character
|
|
extension; eg. FILENAME.EXT
|
|
|
|
(*) DirectZAP is a variant of ZedZap. The difference is that the
|
|
transmitter only escapes CAN (18H). It is not recommended to use the
|
|
DirectZAP protocol when two systems are connected via a packet
|
|
switching network, or via another layer sensitive to control
|
|
characters such as XON and XOFF.
|
|
|
|
(**) The minimum protocol requirement for an EMSI implementation is
|
|
to support plain Zmodem (16- or 32-bit CRC, 1,024 byte packets) which
|
|
is represented by the ZMO flag in EMSI.
|
|
|
|
=====================================================================
|
|
Mailer product code
|
|
---------------------------------------------------------------------
|
|
The hexadecimal representation of the EMSC product code assigned to
|
|
the mailer. Currently, the EMSC codes are the same as the FTSC
|
|
assigned codes.
|
|
|
|
=====================================================================
|
|
Mailer name
|
|
---------------------------------------------------------------------
|
|
Specifies the name of the E-Mail system sending the EMSI packet.
|
|
|
|
=====================================================================
|
|
Mailer version
|
|
---------------------------------------------------------------------
|
|
The version number of the mailer software, ie. "1.10", "2.00".
|
|
|
|
=====================================================================
|
|
Mailer serial number
|
|
---------------------------------------------------------------------
|
|
The serial number, distribution source, version information, etc.
|
|
This field is usually displayed like:
|
|
|
|
Name<sp>Version/Serial_number
|
|
|
|
eg.
|
|
|
|
AirMail 0.10/Beta-2
|
|
|
|
=====================================================================
|
|
Extra fields
|
|
---------------------------------------------------------------------
|
|
The extra fields make the EMSI handshake protocol extremely flexible.
|
|
Any program or mailer may add fields to the end of the pre-defined
|
|
structure so that program-specific data may be passed without the
|
|
concern of interferring with other systems.
|
|
|
|
There may be any number of extra fields added to the end of this
|
|
structure. Each EXTRA_FIELD contains two ASCII1 strings:
|
|
|
|
PRODUCT_IDENTIFIER A unique "tag" that defines a specific
|
|
program (such as a mailer or a utility).
|
|
|
|
SPECIFIC_DATA ASCII text that is specific data to the
|
|
program defined in PRODUCT_IDENTIFIER. With
|
|
this structure, any program can add its own
|
|
data to the EMSI packet without affecting
|
|
other applications.
|
|
|
|
It is recommended that you contact the author of this document should
|
|
you have any EXTRA_FIELDS that you may think worthwhile for other
|
|
developers to implement and support.
|
|
|
|
Predefined extra fields
|
|
---------------------------------------------------------------------
|
|
The following extra fields have been defined to date.
|
|
|
|
PRODUCT_IDENTIFIER : IDENT
|
|
|
|
Purpose : General identification of system that
|
|
includes all information to generate a St.
|
|
Louis-format nodelist entry.
|
|
|
|
SPECIFIC_DATA : system_name,
|
|
city,
|
|
operator_name,
|
|
phone_number,
|
|
baud_rate,
|
|
flags: ASCII2;
|
|
|
|
SYSTEM_NAME The name of the system given by the user.
|
|
This would normally be a company name, BBS
|
|
name or other identifying text.
|
|
|
|
CITY The geographical location of the system.
|
|
|
|
OPERATOR_NAME The name of the person primarily responsible
|
|
for the system.
|
|
|
|
PHONE_NUMBER The telephone number of the system, or
|
|
"-Unpublished-" if the telephone number is
|
|
unpublished. This MUST be in the standard
|
|
format COUNTRY-CITY-NUMBER. Leading zeros
|
|
should be stripped from the city code,
|
|
ie. Stockholm (Sweden) has a city code of 08,
|
|
included in an EMSI packet, it would read
|
|
46-8-<number>.
|
|
|
|
BAUD_RATE The maximum baud rate supported by the
|
|
system. This is NOT necessarily the same as
|
|
the highest DTE rate.
|
|
|
|
FLAGS The St. Louis (FTSC) nodelist flags
|
|
associated with the system.
|
|
|
|
|
|
PART III - Interactive Electronic Mail Standard Idenfitication
|
|
|
|
Connecting two IEMSI capable systems
|
|
=====================================================================
|
|
Two specific labels are used when discussing the IEMSI definitions.
|
|
The Client, which in this case is the Terminal software, and the
|
|
Server, which in this case is the interactive on-line software,
|
|
such as a BBS package or database system. It is assumed that the
|
|
Client and the Server have established a data link and that no
|
|
data has been transmitted by the Server.
|
|
|
|
STEP 1, IEMSI INIT
|
|
|
|
There is no specific sequence of events in the IEMSI definition. The
|
|
Client must monitor incoming data and if the EMSI_IRQ sequence is
|
|
detected, it attempts to negotiate an IEMSI session with the Server.
|
|
Under no circumstances is the Client allowed to transmit an EMSI_ICI
|
|
packet prior to receiving the EMSI_IRQ sequence from the Server.
|
|
All IEMSI sequences and EMSI sequences used during an IEMSI session
|
|
are terminated by a single <CR>. There are no exceptions to this.
|
|
|
|
|
|
STEP 2A, Server
|
|
|
|
+-+------------------------------------------------------------------+
|
|
:1: Tries=0, T2=60 seconds :
|
|
+-+------------------------------------------------------------------+
|
|
:2: Transmit EMSI_IRQ sequence :
|
|
+-+------------------------------------------------------------------+
|
|
:3: T1=20 seconds, increment Tries :
|
|
: : :
|
|
: : Tries>3? Discontinue IEMSI negotiation. :
|
|
+-+------------------------------------------------------------------+
|
|
:4: Wait for EMSI_ICI packet until any of the timers have expired. :
|
|
: : :
|
|
: : If T2 has expired, discontinue IEMSI negotiation. :
|
|
: +------------------------------------------------------------------+
|
|
: : If T1 has expired, go to step 2. :
|
|
: +------------------------------------------------------------------+
|
|
: : If EMSI_ICI seen, go to step 5. :
|
|
: +------------------------------------------------------------------+
|
|
: : Go to step 4. :
|
|
+-+------------------------------------------------------------------+
|
|
:5: Receive EMSI_ICI packet :
|
|
: +------------------------------------------------------------------+
|
|
: : Packet received OK? Transmit EMSI_ISI packet, and :
|
|
: : go to step 6. :
|
|
: +------------------------------------------------------------------+
|
|
: : Packet not received OK? Transmit EMSI_NAK and go to step :
|
|
: : 3. :
|
|
+-+------------------------------------------------------------------+
|
|
:6: Tries=0 :
|
|
+-+------------------------------------------------------------------+
|
|
:7: T1=20 seconds, increment Tries :
|
|
: : :
|
|
: : Tries>3? Discontinue IEMSI negotiation. :
|
|
+-+------------------------------------------------------------------+
|
|
:8: Wait for EMSI_ACK/EMSI_NAK until any of the timers have expired. :
|
|
: : :
|
|
: : If T2 has expired, discontinue IEMSI negotiation. :
|
|
: +------------------------------------------------------------------+
|
|
: : If T1 has expired or EMSI_NAK received, transmit EMSI_ISI packet :
|
|
: : again and go to step 7. :
|
|
: +------------------------------------------------------------------+
|
|
: : If EMSI_ACK received, go to step 9. :
|
|
: +------------------------------------------------------------------+
|
|
: : Go to step 8. :
|
|
+-+------------------------------------------------------------------+
|
|
:9: IEMSI session successfully established, exit. :
|
|
+-+------------------------------------------------------------------+
|
|
|
|
The Server must monitor its incoming data channel for 'normal' data,
|
|
ie. data not transmitted as IEMSI sequences, to detect if the user is
|
|
attempting to log-in without the use of IEMSI. The only basic
|
|
restriction this imposes on the Server is that user names and/or IDs
|
|
may not start with the character '*' since all EMSI/IEMSI sequences
|
|
start with this character.
|
|
|
|
All processing of the information in the EMSI_ICI packet must be done
|
|
after transmitting the EMSI_ISI packet and receiving two EMSI_ACK
|
|
sequences in return.
|
|
|
|
|
|
STEP 2B, Client
|
|
|
|
Note that this assumes that the Client has seen the EMSI_IRQ sequence
|
|
transmitted by the Server and that the negotiation is ready to take
|
|
place.
|
|
|
|
+-+------------------------------------------------------------------+
|
|
:1: Tries=0, T2=60 seconds :
|
|
+-+------------------------------------------------------------------+
|
|
:2: Transmit EMSI_ICI packet :
|
|
+-+------------------------------------------------------------------+
|
|
:3: T1=20 seconds, increment Tries :
|
|
+-+------------------------------------------------------------------+
|
|
:5: Tries>3 or T2 expired? Discontinue IEMSI negotiation. :
|
|
: +------------------------------------------------------------------+
|
|
: : If T1 has expired, go to step 2. :
|
|
: +------------------------------------------------------------------+
|
|
: : If EMSI_ISI seen, go to step 6. :
|
|
: +------------------------------------------------------------------+
|
|
: : Go to step 5. :
|
|
+-+------------------------------------------------------------------+
|
|
:6: Receive EMSI_ISI packet :
|
|
: +------------------------------------------------------------------+
|
|
: : Packet received OK? Transmit EMSI_ACK packet twice, :
|
|
: : and go to step 7. :
|
|
: +------------------------------------------------------------------+
|
|
: : Packet not received OK? Transmit EMSI_NAK and go to step:
|
|
: : 3. :
|
|
+-+------------------------------------------------------------------+
|
|
:7: IEMSI session successfully established, exit. :
|
|
+-+------------------------------------------------------------------+
|
|
|
|
All processing of the information in the EMSI_ISI packet must be done
|
|
after transmitting two EMSI_ACK sequences in return.
|
|
|
|
If either of the ICI or ISI packets are NAK'd three consecutive times,
|
|
the session negotiation attempt is terminated and the Client proceeds
|
|
as it would have done should the Server not have supported IEMSI.
|
|
|
|
|
|
IEMSI packet and sequence definitions
|
|
=====================================================================
|
|
|
|
=====================================================================
|
|
EMSI ACK **EMSI_ACK<crc16><CR>
|
|
---------------------------------------------------------------------
|
|
EMSI ACK is transmitted by either Client or Server as a positive
|
|
acknowledgement of the valid receipt of an IEMSI packet such as
|
|
EMSI_ISI and EMSI_ICI. During an IEMSI session, this sequence can,
|
|
however, be used as a positive acknowledgement for other IEMSI
|
|
packets. Redundant EMSI_ACK sequences should be ignored.
|
|
|
|
=====================================================================
|
|
EMSI NAK **EMSI_NAK<crc16><CR>
|
|
---------------------------------------------------------------------
|
|
EMSI NAK is transmitted by either Client or Server as a negative
|
|
acknowledgement of the valid receipt of an IEMSI packet such as
|
|
EMSI_ISI and EMSI_ICI. During an IEMSI session, this sequence can,
|
|
however, be used as a negative acknowledgement for other IEMSI
|
|
packets. Redundant EMSI_NAK sequences should be ignored.
|
|
|
|
=====================================================================
|
|
EMSI IRQ **EMSI_IRQ<crc16><CR>
|
|
---------------------------------------------------------------------
|
|
Similar to EMSI_REQ which is used by mailer software to negotiate a
|
|
mail session. IRQ identifies the Server as being capable of
|
|
negotiating an IEMSI session. When the Client detects an IRQ sequence
|
|
in its inbound data stream, it attempts to negotiate an IEMSI
|
|
session.
|
|
|
|
=====================================================================
|
|
EMSI IIR **EMSI_IIR<crc16><CR>
|
|
---------------------------------------------------------------------
|
|
The IIR (Interactive Interrupt Request) sequence is used by either
|
|
Client or Server to abort the current negotiation. This could be
|
|
during the initial IEMSI handshake or during other interactions
|
|
between the Client and the Server.
|
|
|
|
=====================================================================
|
|
EMSI ICI **EMSI_ICI<len><data><crc32><CR>
|
|
---------------------------------------------------------------------
|
|
The ICI packet is used by the Client to transmit its configuration
|
|
and Server-related information to the Server. It contains Server
|
|
parameters, Client options, and Client capabilities.
|
|
|
|
=====================================================================
|
|
EMSI ISI **EMSI_ISI<len><data><crc32><CR>
|
|
---------------------------------------------------------------------
|
|
The ISI packet is used by the Server to transmit its configuration
|
|
and Client-related information to the Client. It contains Server data
|
|
and capabilities.
|
|
|
|
=====================================================================
|
|
EMSI ISM **EMSI_ISM<len><data><crc32><CR>
|
|
---------------------------------------------------------------------
|
|
The ISM packet is used to transfer ASCII images from the Server to
|
|
the Client. These images can then be recalled by the Client when
|
|
the Server needs to display a previously displayed image. This will
|
|
be further described in future revisions of this document.
|
|
|
|
=====================================================================
|
|
EMSI CHT **EMSI_CHT<crc16><CR>
|
|
---------------------------------------------------------------------
|
|
The CHT sequence is used by the Server to instruct the Client
|
|
software to enter its full-screen conversation mode function (CHAT).
|
|
Whether or not the Client software supports this is indicated in the
|
|
ICI packet.
|
|
|
|
If the Server transmits this sequence to the Client, it must wait for
|
|
an EMSI_ACK prior to engaging its conversation mode. If no EMSI_ACK
|
|
sequence is received with ten seconds, it is safe to assume that the
|
|
Client does not support EMSI_CHT. If, however, an EMSI_NAK sequence
|
|
is received from the Client, the Server must re-transmit the
|
|
EMSI_CHT sequence. Once the on-line conversation function has been
|
|
sucessfully activated, the Server must not echo any received
|
|
characters back to the Client.
|
|
|
|
=====================================================================
|
|
EMSI TCH **EMSI_TCH<crc16><CR>
|
|
---------------------------------------------------------------------
|
|
The TCH sequence is used by the Server to instruct the Client
|
|
software to terminate its full-screen conversation mode function
|
|
(CHAT).
|
|
|
|
If the Server transmits this sequence to the Client, it must wait for
|
|
an EMSI_ACK prior to leaving its conversation mode. If no EMSI_ACK
|
|
sequence is received with ten seconds, a second EMSI_TCH sequence
|
|
should be issued before the Server resumes operation. If, however, an
|
|
EMSI_NAK sequence is received from the Client, the Server must
|
|
re-transmit the EMSI_TCH sequence.
|
|
|
|
|
|
The EMSI_ICI packet
|
|
=====================================================================
|
|
The following pseudo structure shows the layout of the EMSI_ICI
|
|
packet. Note that the information in the EMSI_ICI packet may not
|
|
exceed 2,048 bytes.
|
|
|
|
EMSI_ICI
|
|
name,
|
|
alias,
|
|
location,
|
|
data#,
|
|
voice#,
|
|
password,
|
|
birthdate,
|
|
crtdef,
|
|
protocols,
|
|
capabilities,
|
|
requests,
|
|
software,
|
|
xlattabl: ASCII1;
|
|
end;
|
|
|
|
EMSI_ICI field definitions
|
|
---------------------------------------------------------------------
|
|
|
|
=====================================================================
|
|
Name and Alias (or Handle)
|
|
---------------------------------------------------------------------
|
|
The name and possible alias (AKA) of the user (Client). This must be
|
|
treated case insensitively by the Server.
|
|
|
|
=====================================================================
|
|
Location
|
|
---------------------------------------------------------------------
|
|
The geographical location of the user, ie. Stockholm, Sweden.
|
|
|
|
=====================================================================
|
|
data# and voice#
|
|
---------------------------------------------------------------------
|
|
Unformatted data and voice telephone numbers of the user. Unformatted
|
|
is defined as the full telephone number, including country and local
|
|
area code. Eg. 46-8-90510 is a telephone number in Stockholm, Sweden.
|
|
|
|
=====================================================================
|
|
Password
|
|
---------------------------------------------------------------------
|
|
The password for the user. This must be treated case insensitively by
|
|
the Server.
|
|
|
|
=====================================================================
|
|
Birthdate
|
|
---------------------------------------------------------------------
|
|
Hexadecimal string representing a long integer containing the birth-
|
|
date of the user in UNIX notation (number of seconds since midnight,
|
|
Jan 1 1970). This must be treated case insensitively by the Server.
|
|
|
|
=====================================================================
|
|
CrtDef
|
|
---------------------------------------------------------------------
|
|
Consisting of four sub-fields separated by commas, this field
|
|
contains from left to right: The requested terminal emulation
|
|
protocol, the number of rows of the user's CRT, the number of columns
|
|
of the user's CRT, and the number of ASCII NUL (00H) characters the
|
|
user's software requires to be transmitted between each line of text.
|
|
|
|
The following terminal emulation protocols are defined:
|
|
|
|
AVT0 AVATAR/0+. Used in conjunction with ANSI. If AVT0 is
|
|
specified by the Client, support for ANSI X3.64 emulation
|
|
should be assumed to be present.
|
|
ANSI ANSI X3.64
|
|
VT52 DEC VT52
|
|
VT100 DEC VT100
|
|
TTY No terminal emulation, also referred to as RAW mode.
|
|
|
|
=====================================================================
|
|
Protocols
|
|
---------------------------------------------------------------------
|
|
The file transfer protocol option specifies the preferred method of
|
|
transferring files between the Client and the Server in either
|
|
direction. The Client presents all transfer protocols it is capable
|
|
of supporting and the Server chooses the most appropriate protocol.
|
|
|
|
DZA* DirectZAP (Zmodem variant)
|
|
ZAP ZedZap (Zmodem variant)
|
|
ZMO Zmodem w/1,024 byte data packets
|
|
SLK SEAlink
|
|
KER Kermit
|
|
|
|
(*) DirectZAP is a variant of ZedZap. The difference is that the
|
|
transmitter only escapes CAN (18H). It is not recommended to use the
|
|
DirectZAP protocol when the Client and the Server are connected via a
|
|
packet switching network, or via another layer sensitive to control
|
|
characters such as XON and XOFF.
|
|
|
|
|
|
=====================================================================
|
|
Capabilities
|
|
---------------------------------------------------------------------
|
|
The capabilities of the user's software. If more than one capability
|
|
is listed, each capability is separated by a comma.
|
|
|
|
The following capability codes are defined:
|
|
|
|
CHT Can do full-screen on-line conversation (CHAT).
|
|
MNU Can do ASCII image download (see ISM packet).
|
|
TAB Can handle TAB (ASCII 09H) characters.
|
|
ASCII8 Can handle 8-bit IBM PC ASCII characters.
|
|
|
|
=====================================================================
|
|
Requests
|
|
---------------------------------------------------------------------
|
|
The requests field specifies what the user wishes to do once the
|
|
initial IEMSI negotiation has been successfully completed. If more
|
|
than one capability is listed, each capability is separated by a
|
|
comma.
|
|
|
|
The following request codes are defined:
|
|
|
|
NEWS Show bulletins, announcements, etc.
|
|
MAIL Check for new mail.
|
|
FILE Check for new files.
|
|
HOT Hot-Keys.
|
|
CLR Screen clearing.
|
|
HUSH Do not disturb.
|
|
MORE Page pausing, often referred to as "More".
|
|
FSED* Full-screen editor.
|
|
XPRS <reserved>.
|
|
|
|
(*) Note that this allows the Client to request use of a full-screen
|
|
editor without requiring that it also supports a full-screen terminal
|
|
emulation protocol.
|
|
|
|
=====================================================================
|
|
Software
|
|
---------------------------------------------------------------------
|
|
The name, version number, and optionally the serial number of the
|
|
user's software. Eg. {FrontDoor,2.00,AE000001}.
|
|
|
|
=====================================================================
|
|
XlatTabl
|
|
---------------------------------------------------------------------
|
|
Used for character translation between the Server and the Client.
|
|
This field has not been completely defined yet and should always be
|
|
transmitted as {} (empty).
|
|
|
|
|
|
The EMSI_ISI packet
|
|
=====================================================================
|
|
The following pseudo structure shows the layout of the EMSI_ISI
|
|
packet. Note that the information in the EMSI_ISI packet may not
|
|
exceed 2,048 bytes.
|
|
|
|
EMSI_ISI
|
|
id,
|
|
name,
|
|
location,
|
|
operator,
|
|
localtime,
|
|
notice,
|
|
wait,
|
|
capabilities: ASCII1;
|
|
end;
|
|
|
|
EMSI_ISI field definitions
|
|
---------------------------------------------------------------------
|
|
|
|
=====================================================================
|
|
ID
|
|
---------------------------------------------------------------------
|
|
The name, version number, and optionally the serial number of the
|
|
Server software. Eg. {RemoteAccess,1.10/b5,CS000001}.
|
|
|
|
=====================================================================
|
|
Name
|
|
---------------------------------------------------------------------
|
|
The name of the Server system. Eg. {Advanced Engineering S.A.R.L.}.
|
|
|
|
=====================================================================
|
|
Location
|
|
---------------------------------------------------------------------
|
|
The geographical location of the user, ie. Stockholm, Sweden.
|
|
|
|
=====================================================================
|
|
Operator
|
|
---------------------------------------------------------------------
|
|
The name of the primary operator of the Server software. Eg. {Joaquim
|
|
H. Homrighausen}.
|
|
|
|
|
|
|
|
=====================================================================
|
|
Localtime
|
|
---------------------------------------------------------------------
|
|
Hexadecimal string representing a long integer containing the current
|
|
time of the Server in UNIX notation (number of seconds since midnight,
|
|
Jan 1 1970). This must be treated case insensitively by the Client.
|
|
|
|
=====================================================================
|
|
Notice
|
|
---------------------------------------------------------------------
|
|
May contain copyright notices, system information, etc. This field
|
|
may optionally be displayed by the Client.
|
|
|
|
=====================================================================
|
|
Wait
|
|
---------------------------------------------------------------------
|
|
A single character used by the Server to indicate that the user
|
|
has to press the <Enter> key to resume operation. This is used in
|
|
conjunction with ASCII Image Downloads (see ISM packet).
|
|
|
|
=====================================================================
|
|
Capabilities
|
|
---------------------------------------------------------------------
|
|
The capabilities of the Server software. No Server software
|
|
capabilities have currently been defined.
|
|
|
|
Credits and other notes
|
|
=====================================================================
|
|
The original EMSI specifications were designed by Chris Irwin and
|
|
Joaquim H. Homrighausen. The original IEMSI specifications were
|
|
designed by Joaquim H. Homrighausen and Andrew Milner.
|
|
</PRE>
|
|
|
|
<A HREF="index.htm"><IMG SRC="../images/b_arrow.png" ALT="Back" Border="0">Go Back</A>
|
|
|
|
</BODY>
|
|
</HTML>
|
|
|