Previously, once a pubkey was attempted, you could not use a password.

328:25: warning: ‘pubkey’ may be used uninitialized

TLS 1.2.  For static services and JS sockets, add a new tls_minver
socket property which can be set to use a lower minver (down to the
wildly insecure TLS 1.0).

TLS 1.0 and 1.1 have been not reccomended since 2015, and deprecated
since 2021.

The client_socket_dup is overwritten after with the return value of accept(),
so this was likely a socket/handle leak (since commit 74470573, 17 years ago).

Noticed this only after logging a new error in an SSH connection when this
call to DuplicateHandle() failed for some reason (WinError 6), but it seems
like it's been redundant code for a long time now. So just ace it and possibly
fix a resource leak.

scfgnet.c:1463:25: warning: result of comparison of constant 100000 with expression of type 'uint16_t' (aka 'unsigned short') is always true

really no useful way to recover from failure.

This should fix the Clang warning that Deuce reported:
str.cpp:131:18: warning: passing an object that undergoes default argument promotion to 'va_start' has undefined behavior

Still using BOOL where we need Win32 API compatibility.
Using JSBool instead of BOOL or bool where it matters.
Changed most relevant TRUE/FALSE to true/false too (though it's not as critical).

You shouldn't need to #include <stdbool.h> anywhere now - gen_defs.h should do that automatically/correctly based on the language/version/tool. In C23, stdbool.h isn't even needed for bool/true/false definitions (they're keywords), so we don't bother including stdbool.h in that case.
Microsoft didn't define __STDC_VERSION__ in their older tool chains (even though they were C99 compatible and had stdbool.h), so we use a _MSC_VER check to know that there's a stdbool.h we should use in that case.

For other/old compilers (e.g. Borland C) we #define bool/true/false following the pattern of stdbool.h (doesn't use a typedef).

I didn't convert UIFC yet.

This addresses issue #698

TLS clients don't (currently) add a certificate, so there's no need
to delete it.

Use cryptDestroySession() instead.

With this, it's not strictly necessary to clear cert_list in ssl_sync()
when the certificate changes, but it's still a good idea to prevent
unusable memory from being held onto.

warning: value computed is not used

Now each lock has an easily understandable purpose, and covers the
lowest possible amount of code.

It looks like Windows actually uses the name for matching existing
events, so if two events have the same name, they end up being the
same object.

On Win32, the name param is an LPCSTR which apparently is Microsoft
talk for const char *.

In C we're allowed to do whatever we want, but in C++, this matters
more.

Just running git commit --amend doesn't do -a it seems. :)

This should fix a long-standing issue where someone could connect to
the SSH port and do nothing, which would prevent other incoming
terminal sessions from being accepted until it times out.

Unfortunately, this means that Synchronet can't send any data until
authentication is completed, which means useful messages about why
you're being disconnected (ie: "Sorry, all terminal nodes are in use or otherwise unavailable.")
as well as usless information nobody ever cares about (ie: The IP
you're connecting from, that it is resolving your hostname, etc).
can no longer be sent to the user.

Reported by Max (WESTLINE)...

Introduced in commit 75c5c9e5, since we are now calling the set_state()
callback periodically, and in sbbsctrl, it sets/resets the pause button
checked (depressed) state in response to this callback (should it?), this was
resetting the pause button checked/depressed state peridically (at the
configured sem file check interval, default 2 seconds).

The fix: if the new server state is the same as the previously set server
state, don't call the set_state() callback. I considered this as a potential
optimization when I first wrote that commit, but didn't see any obvious
downside to calling the set_state() callback redundantly. Now that I see a
downside, let's implement this saving/checking of the state to avoid
redundant "set" calls.

... with a socket descriptor value of -1.

The 5th character must be a digit.

Prevent future stupidity such as happened with recently added and then
fixed NODE_USER @-code.

Since "NODE*" is a match for a node number status (ugh), and this comparison
happened before the comparison for "NODE_USER", we'd never hit that condition.
Thought I tested this before original commit, but I guess I did not. Oops.

This recent enhancement (Commit 61a3ab2d) introduced security and usability
concerns.

So I created (and am now using where requested) a wrapper for formatting
text.dat/ini strings which will automaticlaly detect @-code encoded strings
and expand/use them *only* (instead of printf %-specifiers).

This might impact issue #696 since although unintentionally, it actually was
possible to mix @-codes and %-specifier usage in certain (node status)
text.dat/ini strings, but that should not be possible now. It's either/or:
@-codes or %-specifiers, not both.

Needed for exactly reproducing built-in node status string formatting using
@-codes (only).

Note: format specifiers (e.g. %s) cannot be combined with @-codes (use one or
the other, not both).

Fixes issue #696

If you need additional text strings to support @-codes, you'll have to specify
them explicitly in feature request issues.

We have checks/loops/timeouts waiting for active clients to disconnect and
child thread threads to terminate whenever shutting down or recycling already,
so this should be safe. This pretty simple change fixes issue #236 (can't
terminate server under heavy load).

Also as part of this commit, introduced the ability to "pause" a server
(prevent it from accepting new connections) with the ctrl/pause semaphore
file or via the MQTT server/pause (and resume) topics. This feature is useful
when debugging server issues where you don't necessarily want to fully
shutdown/terminate the server, but don't want any new connections to be
accepted (the listen backlog will fill up with incoming connections though).
Unlike a server shutdown, a server pause can be "undone" via MQTT (by
publishing a message to the "resume" topic).

The "pause" semaphore file is just an "existence" semaphore file - its
date/time stamp doesn't matter. If the file exists, the server will enter
a paused state (and periodically log messages to that fact) until the semfile
is deleted.

This server pause feature is not the same as the pause button function in
sbbsctrl, which just pauses server log output.

that doesn't log an error

Support was accidentally removed as part of commit 22e8d2e3, meaning
the ftpalias.cfg wasn't used at all in responses to the MLSx commands as
reported by Max (WESTLINE) using Total Commander, FileZilla and Directory
opus. The traditional "LIST" commands still worked fine with ftpalias.cfg
contents just fine.

The reason this code was accidentally removed was due to the errant
copy/pasted comparison with startup->html_index_file that did not belong here
and made the block appear related to HTML index file generation. It was not.
This was just a bug in the initial implementation of MLSx support in
commit d4deb4b3.

Also included in this commit:
- Return the date/size of the user's QWK packet file, if it exists, in MLSx
  response.
- send_mlsx_entry() won't report negative time_t values as file modify dates
 (flength returns -1 upon failure/file-not-found).
- get_owner_name() returns the string, making it easier to use in function
  calls.

There appears to still be some work to do to make the MLSx commands fully
compliant with RFC 3659 (e.g. "mlst filename" from ftpalias.cfg should work
but does not), but at least FileZilla displays ftpalias.cfg files and
directories correctly now.

Reusing the variable 'str' here for multiple purposes meant the QWK packet
filename was overwritten by the owner name (the system's BBS-ID):

 ftp> mlsd
 229 Entering Extended Passive Mode (|||2001|)
 150 Opening ASCII mode data connection for MLSD.
 Type=file;Perm=r;UNIX.ownername=VERT; 00index
 Type=cdir;Perm=elc;UNIX.ownername=VERT; /
 Type=file;Perm=r;UNIX.ownername=VERT; VERT

That last file there should have been "VERT.qwk"

Since lock_ssl_cert() is a reader lock, there shouldn't be a whole
lot of contention on aquiring it anyway, and we can thundering herd
our way out of it when it clears.