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b2f:bcf_v0 [2025/02/14 09:02] – [ASCII Message Transfer Mode] f4hofb2f:bcf_v0 [2025/02/14 10:45] (current) – [Binary File Transfer Mode] f4hof
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   * As it is an extension of the basic protocol, the SID extension field MUST also advertise the ASCII Basic Protocol with the letter F. A SID with the letter ''B'' but no ''F'' will be treated as if neither extensions have been advertised.    * As it is an extension of the basic protocol, the SID extension field MUST also advertise the ASCII Basic Protocol with the letter F. A SID with the letter ''B'' but no ''F'' will be treated as if neither extensions have been advertised. 
  
-===== Transfer Modes =====+The Binary Compressed Forward protocol MUST operate over a [[https://en.wikipedia.org/wiki/8-bit_clean|8-bit clean]] communication bearer, which provides reliable and ordered delivery.
  
-The actual message content is transferred in a different format from the ASCII Basic Protocol. +===== Commands =====
-  +
-The format used is derived from the YAPP protocol which is very reliable. Each message is made up of a header, blocks of data, an end of message marker and a checksum. +
  
-This is directly equivalent to the transfer of one message in the ASCII Basic Protocol. +The command list almost stays the same as the ASCII Basis Protocol.
  
-Unlike YAPP transfers, there is no individual packet acknowledgement during the transmission of messages, the protocol is thus simpler and more efficient+The main change is the [[b2f:ascii#pending_mail_proposal|pending mail proposal]] is replaced by the following proposals.
  
-==== ASCII Message Transfer Mode ====+^ Proposal ^ Usage ^ 
 +| ''FA'' | Pending ASCII Message Proposal | 
 +| ''FB'' | Pending Binary File Proposal | 
 + 
 +The proposal format stays the same as the one described in the [[b2f:ascii#pending_mail_proposal|pending mail proposal]] specification: 
 + 
 +==== Pending ASCII Message Proposal ==== 
 + 
 +==== Pending Binary File Proposal ==== 
 + 
 +===== Transfer Mode ====
 + 
 +The message/file payload is transferred using a different format from the ASCII Basic Protocol. 
 + 
 +Each message is made up of a header, blocks of data, an end-of-message marker, and a checksum.   
 + 
 +Unlike YAPP transfers, there is no individual packet acknowledgement during the transmission of messages. The protocol is thus simpler and more efficient.  
 + 
 +As with the underlying protocol, the channel direction is immediately reversed after the completion of a transfer batch. 
 +==== ASCII Message Transfer Header ==== 
 + 
 +FIXME proposal format definition
  
 Message header format: Message header format:
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 Security considerations: Security considerations:
   * If you're using a memory-unsafe language, you SHOULD pay extra care with the attribute size field to avoid buffer overflow attacks.   * If you're using a memory-unsafe language, you SHOULD pay extra care with the attribute size field to avoid buffer overflow attacks.
-==== Binary File Transfer Mode ====+==== Binary File Transfer Header ==== 
 + 
 +FIXME proposal format definition
  
 Message header format: Message header format:
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 To perform validation, compute the sum of data and checksum bytes, modulo 256. The checksum is considered valid if the result of the last calculation equals 0. To perform validation, compute the sum of data and checksum bytes, modulo 256. The checksum is considered valid if the result of the last calculation equals 0.
  
-In case of a checksum error, the message or the file is ignored and the system issues a disconnect request after having sent the comment : +In case of a checksum error
 +  - The message or the file is ignored
 +  - The following comment is sent back. 
 +  - The system issues a disconnect request 
  
 <code>*** Erreur checksum</code> <code>*** Erreur checksum</code>
  
 +===== Transaction flow =====
 +
 +FIXME To be completed
b2f/bcf_v0.1739523757.txt.gz · Last modified: 2025/02/14 09:02 by f4hof