Subj : Solved issue with SyncTerm after up/download on my BBS
To   : AKAcastor
From : Digital Man
Date : Wed Apr 17 2024 11:57 am

  Re: Solved issue with SyncTerm after up/download on my BBS
  By: AKAcastor to All on Tue Apr 16 2024 09:59 pm

 > Solution:
 >
 > The telnet IAC handler in DOSBox-X softmodem.cpp was modified to deny
 > requests to disable binary mode, and in case a client disables binary mode a
 > request to enter binary mode is sent.

This sounds like a hacky-work-around and not a 'fix'.

In binary transmit mode, when the user hits the ENTER key in SyncTERM, it will send just ASCII CR to the telnet server. This is not the proper/normal sequence for the Telnet "NVT" (Network Virtual Terminal) 'enter' key sequence which is CR/LF when not in binary transmit mode.

From https://datatracker.ietf.org/doc/html/rfc854:
    Note that "CR LF" or "CR NUL" is required in both directions
    (in the default ASCII mode), to preserve the symmetry of the
    NVT model.

If ASCII (non-binary-tx) mode is negotiated succesfully when SyncTERM first connects to telnet server, then it should be free to return to ASCII mode later.

It just sounds like there's a bug in the DOSBOX-X terminal server with tracking the remote and/or local "BINARY TX" state and that needs to be fixed rather than just blindly rejecting requests to exit binary transmission mode.

Maybe you would have had better luck with DOSBOX-staging instead of of DOSBOX-X?
-- 
                                            digital man (rob)

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