Text 8064, 524 rader
Skriven 2016-02-27 12:25:44 av Stephen Hurd (44.fido-ftscpubl)
Kommentar till en text av FTSC
Ärende: FSP-1040.001 draft 0
============================
**********************************************************************
FTSC FIDONET TECHNICAL STANDARDS COMMITTEE
**********************************************************************
Publication: FSP-1040
Revision: 1
Title: Packet Type 2 Compatible Formats
Author: Stephen Hurd 1:103/1
Date: 2016-02-11
----------------------------------------------------------------------
Status of this document
-----------------------
This document is a Fidonet Standard Proposal (FSP), issued by Stephen
Hurd for the benefit of the Fidonet community.
This document specifies an optional Fidonet standard protocol for
the Fidonet community, and requests discussion and suggestions for
improvements.
This document is released to the public domain, and may be used,
copied or modified for any purpose whatever.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL
NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL"
in this document are to be interpreted as described in FTA-1006.
Contents
--------
1. Fidonet Packets
2. Original Type 2 Packet
3. Type 2+ Packet
4. Type 2.2 Packet
5. Packed Message
6. Comparison of Headers
7. Bibliography
----------------------------------------------------------------------
1. Fidonet Packets
------------------
In Fidonet terms, a "packet" is a file which contains zero or more
separate messages to be transfered together to a system. The
"original" packet format only supported 3D node addressing (zone, net
and node numbers) so different new types of packets were developed.
None of them have previously been ratified as a standard despite being
in common use on Fidonet.
These type 2 "compatible" formats all use a similar fixed-length
header and the same packet message format. Values in these headers
are in "Little-endian" or "Intel" format with the "least-significant"
or "low order" byte first followed byte the next most significant up
to the length of the field. All integer values SHOULD be treated as
unsigned, though some notations MAY treat them as signed values (ie:
Policy 4 mentions address "-1/-1") if a signed value is used, it MUST
be in twos-compliment little-endian format.
After the last packed message, there are two NUL characters to
indicate the end of the packet.
A type 2 packet parser which ignores invalid values in some fields
is able to process all three types (with some loss of information).
The type 2+ packet supports 4D addressing, includes product version
information, and supports a "capability word" method of advertising
support for new packet types. It is highly compatible with type 2
packets (any type 2 processor should work with a type 2+ packet).
The type 2.2 packet supports 5D addressing, but is not as compatible
with type 2 format as it redefines some rarely-used fields,
(specifically, date/time and baud) and does not protect the origin
address when the originating system is a point.
It is therefore RECOMMENDED that without prior arrangement between the
systems on both sides of the link, that type 2+ packets be used rather
than 2.2 packets for Fidonet.
2. Original Type 2 Packet
-------------------------
Originally defined in FSC0001, supports 3D addressing only. This can
cause problems when transferring them to/from points, and across
domain gateways.
This header has eighteen fields specified below:
,-------------------------------------------------------------------.
| Name | Offset | Bytes | Type | Description |
+----------+--------+-------+-------+-------------------------------+
| origNode | 0 | 2 | Int16 | Node number packet is from |
| destNode | 2 | 2 | Int16 | Node number packet is to |
| year | 4 | 2 | Int16 | Year packet was created |
| month | 6 | 2 | Int16 | Month " " " |
| day | 8 | 2 | Int16 | Day " " " |
| hour | 10 | 2 | Int16 | Hour " " " |
| minute | 12 | 2 | Int16 | Minute " " " |
| second | 14 | 2 | Int16 | Second " " " |
| baud | 16 | 2 | Int16 | See Notes |
| Type | 18 | 2 | Int16 | MUST have a value of 2 |
| origNet | 20 | 2 | Int16 | Network number packet is from |
| destNet | 22 | 2 | Int16 | Network number packet is to |
| prodCode | 24 | 1 | Int8 | Assigned by the FTSC |
| serialNo | 25 | 1 | Int8 | See Notes |
| password | 26 | 8 | Str | Packet password, NUL padded |
| origZone | 34 | 2 | Int16 | Zone number packet is from |
| destZone | 36 | 2 | Int16 | Zone number packet is to |
| fill | 38 | 20 | Str | SHOULD be NULs |
`----------+--------+-------+-------+-------------------------------'
Notes:
origZone/destZone
Older software MAY not populate these fields. If origZone is
specified and the packed messages do not have a zone specified in
them, software MAY assume that origZone defines the "default zone"
for packed messages.
origNet/origNode
These define the origin of the packet, not the messages in the
packet.
origNet/origNode
These define the destination of the packet, not the messages in the
packet.
year/month/day/hour/minute/second
SHOULD reflect the UTC time when the packet is created. However,
software MUST be able to handle this being in local time. Further,
since some packet types (such as 2.2) redefine these bytes, programs
SHOULD function normally if these are invalid or unexpected values.
baud
Not widely used. SHOULD be set to zero unless the maximum common
baud rate between the two systems is known at the time of packet
creation. If this field is two, the packet is a type 2.2 packet as
specified in part 4.
prodCode
As defined in the latest FTA-1005, the product code assigned by the
FTSC to the software which creates the packet. A value of 254
indicates the software has not been assigned a product code. If
this value is 255, indicates this is part of a two-byte product
code (see note for serialNo).
serialNo
The contents of this field are not well defined, and this field
SHOULD NOT be used for anything exception informational purposes
(such as logging). When the software generating the packet has been
issued a two-byte product code, it MAY place the most-significant
byte in this field.
password
NUL-padded password up to eight characters long. Software SHOULD
NOT allow NULs in passwords, and when reading this field, any bytes
after the first NUL SHOULD be treated as though they are also NUL.
Keep in mind that an eight character password will not have a NUL
in this field at all, so this is not a NUL terminated string.
fill
This SHOULD be filled with NUL characters when written and ignored
when read.
3. Type 2+ Packet
-----------------
Originally specified in FSC-0039, then updated by FSC-0048, this
introduced a mechanism to detect packet type support which, due to
multiple incompatible "type 3" packet formats, never really caught on.
This "Capability Word" feature is not specified in this document.
The Type 2+ packet added point information and zone information before
FTS-0001 was updated to include zones. As a result, the zone numbers
are in different places in the Type 2 and Type 2+ packet definitions.
Type 2+ was extended to include zone information in the same location,
so the type 2+ packet has the zone information twice. Software
creating or modifying packets MUST set these two sets of zone fields
to the same values.
In the following table, fields on lines beginning with an "H" reflect
changes from the type two packet above.
,-------------------------------------------------------------------.
| Name | Offset | Bytes | Type | Description |
+----------+--------+-------+-------+-------------------------------+
| origNode | 0 | 2 | Int16 | Node number packet is from |
| destNode | 2 | 2 | Int16 | Node number packet is to |
| year | 4 | 2 | Int16 | Year packet was created |
| month | 6 | 2 | Int16 | Month " " " |
| day | 8 | 2 | Int16 | Day " " " |
| hour | 10 | 2 | Int16 | Hour " " " |
| minute | 12 | 2 | Int16 | Minute " " " |
| second | 14 | 2 | Int16 | Second " " " |
| baud | 16 | 2 | Int16 | See Notes |
| Type | 18 | 2 | Int16 | MUST have a value of 2 |
| origNet | 20 | 2 | Int16 | Network number packet is from |
| destNet | 22 | 2 | Int16 | Network number packet is to |
| prodCode | 24 | 1 | Int8 | Assigned by the FTSC |
| | | | | (Low byte only) |
H prodVerM | 25 | 1 | Int8 | Major Version Number |
| password | 26 | 8 | Str | Packet password, NUL padded |
| origZone | 34 | 2 | Int16 | Zone number packet is from |
| destZone | 36 | 2 | Int16 | Zone number packet is to |
H auxNet | 38 | 2 | Int16 | origNet when orig is a point |
H capValid | 40 | 2 | Int16 | See Notes |
H prodCodH | 42 | 1 | Int8 | Assigned by the FTSC |
H | | | | (High byte only) |
H prodVerN | 43 | 1 | Int8 | Minor Version Number |
H capWord | 44 | 2 | Int16 | See Notes |
H origZ2 | 46 | 2 | Int16 | See Notes |
H destZ2 | 48 | 2 | Int16 | See Notes |
H origPnt | 50 | 2 | Int16 | Point number packet is from |
H destPnt | 52 | 2 | Int16 | Point number packet is to |
H prodData | 54 | 4 | Int32 | Product-specific data |
`----------+--------+-------+-------+-------------------------------'
Notes:
auxNet
If origNet is 65535 (0xffff), indicates that the originator is a
point, and the originating network can be found in this field.
Some old software may not follow this convention, so the network
number may be found in either of the two fields. When parsing a
type 2+ packet, if origNet is 65535, the software MUST use the
value from the auxNet field. When creating a packet, if the
originating system is a point, it SHOULD set origNet to 65535 and
put the net number in this field. In the case where the originating
net is 65535 (As recommended by Policy 4), it SHOULD be placed in
both origNet and auxNet.
capValid
Byte-swapped copy of the least-significant 15 bits of capWord.
That is to say that the most significant bit of capWord is masked
off, and the resulting two bytes are swapped. In C:
capValid = ((capWord & 0x7f00) >> 8) | ((capWord & 0xff) << 8));
If the capValid and capWord fields do not match, the packet SHOULD
NOT be processed as a type 2+ packet.
prodVerM
Major version number of product generating the packet. This
replaces the serialNo field of packet type 2.
prodCodH
High (most-significant) byte of FTSC-assigned product code.
prodVerN
Minor version number of product generating the packet.
capWord
Capability Word. Not specified in this document, SHOULD have a
value of 1. MUST at least have the least significant bit set (ie:
be an odd number) or the packet is not a valid type 2+ packet.
origZ2
A copy of origZone. If origZone and origZ2 are different, the
non-zero one SHOULD be used. If neither is zero, origZ2 SHOULD be
used. A compliant program MUST set these two fields to the same
value.
destZ2
A copy of destZone. As with origZ2, this is the "preferred" copy
for software to use.
origPnt
Point number of the originating system.
destPnt
Point number of the destination system.
prodData
Value defined by the holder of the FTSC product code specified.
4. Type 2.2 Packet
------------------
Originally specified in FSC-0045, this packet format supports full 5D
addressing.
The type 2.2 packet format adds both point and domain information, but
replaces some rarely used fields, so is not as compatible with type 2
as type 2+ is.
In the following table, fields on lines beginning with an "H" reflect
changes from the type two packet in section 2.
,-------------------------------------------------------------------.
| Name | Offset | Bytes | Type | Description |
+----------+--------+-------+-------+-------------------------------+
| origNode | 0 | 2 | Int16 | Node number packet is from |
| destNode | 2 | 2 | Int16 | Node number packet is to |
H origPnt | 4 | 2 | Int16 | Point number packet is from |
H destPnt | 6 | 2 | Int16 | Point number packet is to |
H fill | 8 | 8 | Str | MUST be NULs |
H subType | 16 | 2 | Int16 | MUST have a value of 2 |
| Type | 18 | 2 | Int16 | MUST have a value of 2 |
| origNet | 20 | 2 | Int16 | Network number packet is from |
| destNet | 22 | 2 | Int16 | Network number packet is to |
| prodCode | 24 | 1 | Int8 | Assigned by the FTSC |
H prodRev | 25 | 1 | Int8 | See Notes |
| password | 26 | 8 | Str | Packet password, NUL padded |
| origZone | 34 | 2 | Int16 | Zone number packet is from |
| destZone | 36 | 2 | Int16 | Zone number packet is to |
H origDom | 38 | 8 | Str | Domain packet is from, |
H | | | | NUL padded |
H destDom | 46 | 8 | Str | Domain packet is to, |
H | | | | NUL padded |
H prodData | 54 | 4 | Int32 | Product-specific data |
`----------+--------+-------+-------+-------------------------------'
origPnt
Point number of the originating system. Replaces the year in type 2
packets.
destPnt
Point number of the destination system. Replaces the month in type
2 packets.
subType
Always set to 2. Replaces the baud from type 2 packets, indicates
this is a type 2.2 packet.
prodRev
"Product revision level" software assigned a 2-byte FTSC product
code SHOULD put the most significant byte in this field, but some
software MAY put a product version number or other data in this
field.
origDom
NUL padded domain this packet is from.
destDom
NUL padded domain this packet is to.
5. Packed Message
-----------------
All type 2 compatible formats share the same packed message format.
It consists of a fixed-length header followed by variable-length header
followed by the message text.
The fixed-length header is as follows:
,-------------------------------------------------------------------.
| Name | Offset | Bytes | Type | Description |
+-----------+--------+-------+-------+------------------------------+
| Type | 0 | 2 | Int16 | MUST have a value of 2 |
| origNode | 2 | 2 | Int16 | Node number packet is from |
| destNode | 4 | 2 | Int16 | Node number packet is to |
| origNet | 6 | 2 | Int16 | Network number packet is from|
| destNet | 8 | 2 | Int16 | Network number packet is to |
| attribute | 10 | 2 | Int16 | See Notes |
| cost | 12 | 2 | Int16 | See Notes |
`-----------+--------+-------+-------+------------------------------'
Notes:
origNode/origNet
Net and node the message originated from (not the node the packet
was created on).
destNode/destNet
Net and node the message is directed to (not the node the packet is
directed to).
attribute
The attribute word of the message. The following bits are defined,
any undefined bits MUST be zeroed before the message is packed.
When processing these packets, undefined attributes MUST be ignored.
,--------------------------------.
| Bit | Meaning |
+-----+--------------------------|
| 0 | Private |
| 1 | Crash |
| 4 | File Attached |
| 10 | unused |
| 12 | Return Receipt Requested |
| 13 | Is a Return Receipt |
| 14 | Audit Request |
`-----+--------------------------'
Bit 10 SHOULD be retained unchanged when packing messages despite it
being unused. All other bits SHOULD be cleared when packing. The
attributes can be ANDed with 29715 (0x7413) to clear the appropriate
bits.
cost
Expressed in the lowest unit of originators currency. Usually set
to zero.
After the fixed-length portion is a series of NUL terminated strings.
In order, they are:
dateTime (Length = 19)
toUserName (Length <= 36)
fromUserName (Length <= 36)
subject (Length <= 72)
text
The lengths above do NOT include the NUL terminator.
dateTime MUST occupy twenty bytes including the NUL terminator. The
following is the ABNF notation of the format that messages SHOULD use:
digit = "0" / "1" / "2" / "3" / "4" / "5" / "6" / "7" / "8" /
"9"
dayOfMonth = "00" / "01" / "02" / "03" / "04" / "05" / "06" / "07" /
"08" / "09" / "10" / "11" / "12" / "13" / "14" / "15" /
"16" / "17" / "18" / "19" / "20" / "21" / "22" / "23" /
"24" / "25" / "26" / "27" / "28" / "29" / "30" / "31" /
month = "Jan" / "Feb" / "Mar" / "Apr" / "May" / "Jun" / "Jul" /
"Aug" / "Sep" / "Oct" / "Nov" / "Dec"
year = 2*( digit )
hour = "00" / "01" / "02" / "03" / "04" / "05" / "06" / "07" /
"08" / "09" / "10" / "11" / "12" / "13" / "14" / "15" /
"16" / "17" / "18" / "19" / "20" / "21" / "22" / "23" /
"24"
oneToSixty = "00" / "01" / "02" / "03" / "04" / "05" / "06" / "07" /
"08" / "09" / "10" / "11" / "12" / "13" / "14" / "15" /
"16" / "17" / "18" / "19" / "20" / "21" / "22" / "23" /
"24" / "25" / "26" / "27" / "28" / "29" / "30" / "31" /
"32" / "33" / "34" / "35" / "36" / "37" / "38" / "39" /
"40" / "41" / "42" / "43" / "44" / "45" / "46" / "47" /
"48" / "49" / "50" / "51" / "52" / "53" / "54" / "55" /
"56" / "57" / "58" / "59" / "60"
minute = oneToSixty
second = oneToSixty
dateTime = dayOfMonth " " month " " year " " hour ":" minute ":"
second %x00
January 1st, 2016 at 11:15:55pm would therefore be
"01 Jan 16 23:15:55" with a NUL at the end. Notice the two spaces
between the year and the hour.
This format ensures the broadest compatibility however, other
formats are known to be in use. SEAdog has been known to use the
format "Mon 1 Jan 86 02:34" with a single NUL terminator.
After the message text is either the next message or the two-NUL
packet terminator.
Some old systems MAY terminate the message text with an EOF (0x1A)
Some even older systems MAY terminate the message text with an empty
line (0x0D 0x0A 0x0D 0x0A). To detect this, software MAY use the NUL
in the second byte of the Type field to attempt to resynchronize. It
is up to the developer if this needs to be supported.
Since the packed message header only contains 2D addresses, the text
SHOULD have addressing control paragraphs as specified in FTS-4001
added when messages are packed
6. Comparison of Headers
------------------------
The following chart compares the different header fields between the
three packet header types. A '*' before the field name indicates it
is may be incompatible with the Type 2 column value.
,-----------------------------------------.
| Offset | Type 2 | Type 2+ | Type 2.2 |
+--------+----------+----------+----------+
| 0 | origNode | origNode | origNode |
| 2 | destNode | destNode | destNode |
| 4 | year | year |*origPnt |
| 6 | month | month |*destPnt |
| 8 | day | day |*fill |
| 10 | hour | hour |* " |
| 12 | minute | minute |* " |
| 14 | second | second |* " |
| 16 | baud | baud |*subType |
| 18 | Type | Type | Type |
| 20 | origNet | origNet | origNet |
| 22 | destNet | destNet | destNet |
| 24 | prodCode | prodCode | prodCode |
| 25 | serialNo |*prodVerM |*prodRev |
| 26 | password | password | password |
| 34 | origZone | origZone | origZone |
| 36 | destZone | destZone | destZone |
| 38 | fill | auxNet | origDom |
| 40 | " | capValid | " |
| 42 | " | prodCodH | " |
| 43 | " | prodVerN | " |
| 44 | " | capWord | " |
| 46 | " | origZ2 | destDom |
| 48 | " | destZ2 | " |
| 50 | " | origPnt | " |
| 52 | " | destPnt | " |
| 54 | " | prodData | prodData |
`--------+----------+----------+----------'
7. Bibliography
---------------
Administrator, "Key words to indicate requirement levels",
FTA-1006.002
Bush, Randy, "A Basic FidoNet(r) Technical Standard", FTS-0001.016
Howard, Mark A., "A Type-2 Packet Extension Proposal", FSC-0039.004
Vroonhof, Jan, "A Proposed Type-2 Packet Extension", FSC-0048.002
Henderson, Thom, "A Proposal for A New Packet Header Format",
FSC-0045.001
Crocker, D., Overell, P., "Augmented BNF for Syntax Specifications:
ABNF", STD 68
FTSC, "ADDRESSING CONTROL PARAGRAPHS", FTS-4001
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