So Omegix recently asked in the Synchronet Discussion group whether or not
a PETSCII (Commodore) terminal could be used to access his Synchronet BBS.
Now, the answer is "Yes". :-)
The major issues addressed:

- detecting a PETSCII terminal, solved by assigning specific (configurable):
  TCP ports to be used for incoming PETSCII connections, by default:
  port 64 is for 40-column PETSCII and port 128 is for 80-column PETSCII,
  but if the terminal sends a Telnet Window Size reply (e.g. SyncTERM), then
  either size terminal should fine on either port.
  The port numbers are configurable in the [BBS] section of your sbbs.ini
  file using the new keys: PET40Port (default value: 64) and PET80Port
  (default value: 128). Having these keys set doesn't make make the terminal
  server listen on that additional port - you'll need to add more
  IP:port combinations to one of Interfaces values, example:
    TelnetInterface=71.95.196.34,71.95.196.34:64,71.95.196.34:128
  And you don't have to use Telnet for the PETSCII connections - you could use
  RLogin or SSH instead (or in addition).

- support for terminal widths < 80 columns:
  This was achieved through a combination of text.dat changes (numerous),
  new Ctrl-A and @-codes and new optional terminal-width-specific menu files
  (e.g. text/menu/main.40col.asc)
  A side effect of these changes is actually better support for terminals
  *wider* than 80 columns as well!

- support for terminals that don't expand tabs to spaces (e.g. PETSCII):
  The terminal server now handles tab expansion with a run-time settable
  tab-size (default size: 8)

- conditional access based on PETSCII (or small) terminal use (or not):
  + New PETSCII ARS keyword (boolean)
  + New COLS and ROWS ARS keywords (for terminal width and height requirements)
  + New TERM (string) ARS keyword

New @-codes:
  - WORDWRAP, when placed at the top of a file, enables auto-wordwrap for
              lines longer than the terminal width
  - CENTER, the text following before an end of line will be displayed centered
            on the terminal (whatever the width, in columns)
  - CLEAR, like CLS, except it ignores (doesn't display) a CRLF that follows
  - COLS, current number of terminal columns (width)
  - ROWS, current number of terminal rows (height)
  - TERM, the auto-detected or reported terminal type (e.g. ANSI, TTY, etc.)
  - SYSONLY, toggles "echo" (display) off/back-on for non-sysops
            similar to the Ctrl-A( and ) codes, but more convenient to use
            (and PabloDraw won't strip the @-code from the file like it does
             with Ctrl-A codes it doesn't support)

New Ctrl-A codes:
  - \ conditional new-line/continuation when the terminal width is < 80 cols
      prints the new text.dat string LongLineContinuationPrefix

yesno() will now return true if passed a blank string.
noyes() will now return false if passed a blank string.
getstr()'s input length limiting based on terminal width is more broadly
           applied now (not just when using the K_LINE mode flag).

New JS bbs object method: menu_exists(<base_filename>) returns Boolean
New JS console object property: tabstop (Number)
New JS console object methods: getbyte() and putbyte() to recv/send raw byte
    value with (very little) interpretation/intervention by the terminal server
New JS console object method: creturn() - performs a carriage return
    (or equivalent)
New JS (and C) printfile() mode flag: P_TRUNCATE, causes long lines to be
    truncated, rather than displaying causing a line-wrap.

New text.dat strings:
  - NoAccessTerminal (for ARS check failures)
  - LongLineContinuationPrefix (for breaking long lines for 40col terminals)
  - Scanning (replaces a previously hard-coded "Scanning" string)
  - Done (replaces a previusly hard-coded "Done")
  - Scanned  (when finished scannning, clears the progress bar)

I have a new use for it in the v3 Terminal Server, it now follows the
"NO_DOS" option in the [bbs] section of the sbbs.ini file. So if you have
multiple Win32 instances of sbbs (like I do), but only some of them
support DOS programs, you can now use this ARS keyword to enable/disable
access to a program based on the existance of DOS support. For example,
I have some 16-bit DOS message editors where I had the ARS set to
"WIN32", but on my 64-bit Windows instance of sbbs (vert.synchro.net),
16-bit DOS programs aren't supported while on my 32-bit Windows instance
(bbs.synchro.net) they are. So I needed a good run-time check for whether
DOS programs were supported or not and this old ARS keyword seemed the
right fit. For Linux builds, this keyword will only evaluate to true if
built with the USE_DOSEMU option.
This is only true of the Terminal Server - use of "DOS" ARS keyword in
other servers and services will still just evaluate to "false".

- FILE_AREA
- FILE_AREA_DESC
- FILE_LIB
- FILE_LIB_DESC
- FILE_LIB_NUM
- FILE_DIR
- FILE_DIR_DESC
- FILE_DIR_CODE
- FILE_DIR_NUM
- FILE_NAME
- FILE_DESC
- FILE_UPLOADER
- FILE_SIZE
- FILE_CREDITS
- FILE_TIME
- FILE_TIME_ULED
- FILE_TIME_DLED
- FILE_DATE
- FILE_DATE_ULED
- FILE_DAT_DLED
- FILE_TIMES_DLED
Fixed MSG_ATTR @-code (missing SPAM attribute)
New text.dat line: FileHdrDescSeparator, displayed between file detail display
(name, date, uploader, etc.) and extended description, if there is one. This
is used to execute showfileavatar.js.
New JS 'bbs' object properties:
- file_name
- file_description
- file_dir_number
- file_attr
- file_date
- file_credits
- file_uploader
- file_update_date
- file_download_date
- file_download_count
Inspiried by Lon Seidman's now infamous (but likely common) Synchronet sysop
blunder (removing a file rather than downloading it while demonstrating his BBS
on his youtube channel:
- New text.dat line: RemoveFileQ <- using this rather than the vague:
  AreYouSureQ, when prompting to remove a file
- The sysop command to remove files from the batch file flagging prompt has
  been changed from 'D' (delete) to 'R' (remove).
- The 'D' command from the batch file flagging prompt may now be used for
  immediate Download of any flagged file(s).
- When flagging files with '*', treat the same as '*.*'

New Features:
- Multiple bindings for each service
  Use comma-separated interfaces on Interface= lines in the ini file.
  Default is now "0.0.0.0,::"
- IPv6 support
- TLS support for the webserver and (non-static) services
  New TLS option in services.ini (ie: Options=TLS)
- Decrease LEN_SCAN_CMD to 35 chars, increase the CID field to 45 chars,
  and rename the MAIL_CMD string to IPADDR.  I think this frees up the
  note field for SysOp use.

getusrsub() returned the completely wrong sub-board number. It assumed that
getusrgrp() returned a 0-based index when in fact it returns a 1-based group
number. This bug was only visible when using certain @-codes (e.g. "SN",
"SL", "SR", and "SMB_SUB_NUM") when a sub-board was open via Synchronet
internal function (i.e. not via JS MsgBase class). If the current group was the
last group visible to the user, this would cause a crash.

DELETED keywords with other keywords (e.g. "NOT DELETED AND LEVEL 50)":
keyword/values following the broken keyword would be interpretted incorrectly.

Added HOST and IP keywords to allow restricted access/privileges to/for
specific remote hostnames or IP addresses (wildcards allowed).
All string-argument type ARS keywords (e.g. SHELL, PROT, etc.) now support .can
style wildcards.
The current remote client is now used for protocol, host, and IP ARS checking,
when available, so this requires passing the client pointer around (which
explains why so many files are touched by this change) and takes care of a
long standing to-do item (the user's 'modem' value was used for the PROT
value checking, which was not always correct).

by properly const-ifying the appropriate functions and variables.

Not yet tested on Win32

ULM (uploaded megabytes), and DLK and DLM (for downloaded K/Mbytes).

* ULS - uploaded files
* ULB - uploaded bytes
* DLS - downloaded files
* DLB - downloaded bytes

... so now Phil can have a "true" 1:4 upload/download file ratio requirement by
using an ARS of "DLS NOT 4 OR UDFR 25"

* GUEST (shorthand for "REST G")
* QNODE (shorthand for "REST Q").
They're not really much shorter, but the intended function is more clear to the
sysop.

(not rounded up to 100%).

correctly for the BBS (e.g. "Telnet" and "RLogin") until the chk_ar function is
changed to accept a client_t argument.

variants (gmtime_r, localtime_r, and ctime_r) for thread-safe operation on Unix

and group number for a specified (0-based) subnum.

additional keywords and parameters (if present) were not interpretted correctly.

GMT/UTC.

Created system call wrappers.c (and sbbswrap.h) and moved target platform-specific macros and code there.