active_clients is destroyed in cleanup(), so it must be re-initialized inside
the server init/recycle loop.

Fix reported and observed crash in cleanup() (in ftp, mail, websrvr)
when failing to create the temp directory. This was due to cleanup()
being called before the protected integer "active_clients" was
initialized.

Also, md() needs to return the errno value (not a BOOL) since the
caller may be in another DLL with a different errno (which likely
has a value of 0/no error).

... in other non sbbs.dll modules (e.g. *srvr.dll).

So now log error messages elsewhere where appropriate.

DLL-exported and optimized md() a bit.

Eliminate the hack in each server where it will over-write startup host_name
(with the configured Internet email address), if it's blank. This hack was
subject to a race condition where the parent app (e.g. sbbsctrl.exe) would
clear or re-initialize the host_name after the sever threads had initialized.
Instead, just use a function which will return either the startup->host_name
or (fallback to) scfg.inet_addr.

More file existence/length checks, with only a WARNING log level (not error) since some QWKnet nodes apparently like to start concurrent QWK packet downloads and inevitably one finishes first, deleting the file, and the second transfer logs and error. Examples:
  8/14  08:10:06p  2296 <EPHRAM> downloading QWK packet (1320 bytes) in passive mode
  8/14  08:10:06p  3792 <EPHRAM> downloading QWK packet (1320 bytes) in passive mode
  8/14  08:10:06p  2296 <EPHRAM> DATA Transfer successful: 1320 bytes sent in 0 seconds (2640 cps)
  8/14  08:10:06p  3792 <EPHRAM> !DATA ERROR 2 (No such file or directory) line 1376 opening s:\sbbs\data\file/0888.qwk
  8/14  11:28:55p  2576 <POTOGOLD> downloading QWK packet (27129 bytes) in passive mode
  8/14  11:28:55p  2576 <POTOGOLD> DATA Transfer successful: 27129 bytes sent in 0 seconds (54258 cps)
  8/14  11:28:55p  1924 <POTOGOLD> downloading QWK packet (4294967295 bytes) in passive mode
  8/14  11:28:56p  1924 <POTOGOLD> !DATA ERROR 2 (No such file or directory) line 1376 opening s:\sbbs\data\file/0168.qwk

Also some more 64-bit file length support (flength returns an off_t now, not a ulong).
And ftell() returns a long (not a ulong).

The problem: the sysop (me) is not notified of critical errors (e.g. synchro.net zone file problems) in a timely manner.
Part of the solution: notify a configured user (e.g. user #1) via short-message/telegram and email/netmail logged-errors when messages of a configured severity (e.g. "Critical") are logged.
The second part of the solution (coming next) will be allowing timed events to log a message of a configurable severity logged when the event fails (returns a non-zero error level to sbbs).

I'm saving the error-notification-user-number and log-severity as part of the node.cnf file because:
- that's where the validation user number is already set
- I can conceive of a large system were certain node ranges (different instances of sbbs) might want different operators to be notified of logged-errors

This also means I eliminated all the legacy com port/modem stuff from the end of the node.cnf file. None of that is used in sbbs v3.

Also included in this commit are improvements around logging:
- reduce the severity of UDP recvfrom failures in services
- a more detailed log message when the mail server successfully delivers an email (via SMTP) - easier to answer the question: was that email you/they sent delivered successfully?

messages (telegrams) from 128 to 256 bytes to resolve observed truncation of
download notification messages like this:
"Guns N Roses - Hotel Brawl Jam (Live).mp3 was FTP-downloaded by Guest [89.245.6.
199]
You were awarded 2,057,356 cred"

together to keep things atomic:
1. Eliminate eprintf() as sbbs_t::lputs() and sbbs_t::lprintf() do the
   "right thing" (e.g. log to the event log when called from the event_thread).
2. Moved upload_stats() and download_stats() from ftpsrvr.c to getstats.c where
    I plan to make use of them for JS-based upload/download file support.

is actually an authenticated local user (when usernum != 0).

msg_client_hfields() no longer saves the client->user as the SMB SENDERUSERID
hfield when the client hasn't been authenticated (as is the case with normal
SMTP). The SENDUSERIDs were redundant and misleading for unauthenticated
SMTP-received mail messages, so that's now fixed.

(ctrl/node.dab) is constantly closed and re-opened for every non-locking read.
This is really slow across network file systems and unnecessary, so use a
similar optimization as the C++ sbbs_t class where the file can (and normally
is) left open across multiple consecutive reads.
Create/use opennodedat() function.
Uses the new CLOSE_OPEN_FILE() macro from xpdev/filewrap.h.

resolved host-name on "Hostname:" log lines.

reply code.  Maybe this used to be on the same line as the BBS name?

When the command is MLST, fp is NULL, so should not be passed to ftell().

- getnameinfo() was being called with NI_NUMERICHOST in the mail server and
  web server (but nowhere else)
- use a singly-defined macro (STR_NO_HOSTNAME) for the "<no name>" string
  rather than copying it about
- the webserver apparently assumes that session->host_name will always have
  *some* unique value (e.g. the IP address when no hostname is available) - so
  account for that special need <grumble>

to a second thread before the first has the session set active.  Add calls
to lock/unlock the certificate to prevent this.

The better options is likely to have a function that adds the key and socket
and sets the session active in one call and handles the locking internally.

But I'm lazy, so we get the lock functions.

File Existence" is disabled (in SCFG->File Areas... Toggle Options), then don't
check the disk for the file's existence, size, or date/time.

getfname() on a path that ends in a slash, returns an empty string pointer.
Fixed-up some logging output around listing creations.

- use GLOB_MARK to eliminate calls to isdir() in loops
- use stat() rather than calls to flength() and fdate()
- don't call getfiledat() if getfileixb() failed
- profiling info-level log msgs added for index/listing generation, e.g.
  "detailed listing (3459 bytes) of /main/SBBS (45 files) created in 2 seconds"

Fixed bug with indexes generated for directories with the
"Access Files Not In Database" option enabled, files not in database were
excluded from the generated index (e.g. 00index, 00index.html).

error messages.

- include errno description (strerror output)
- exclude (redundant) node number

So I tested the following cases, which all pass:
cwd diralias -> 250 CWD command successful.
cwd /diralias -> 250 CWD command successful.
cwd /diralias/ -> 250 CWD command successful.
cwd /diralias/filename -> 550 filename: No such directory.
cwd /filealias -> 550 filealias: No such diretory.
cwd /filealias/ -> 550 : No such diretory.
retr filealias -> 150 Opening BINARY mode data connection for file transfer.
retr /filealias -> 150 Opening BINARY mode data connection for file transfer.

Hopefully is the end of the fixes for Chrome browser ftp weirdness
(tries to "CWD" to anything/everything to determine if it's a file or not).

- a CWD attempt to a /alias/filename would report 'success' to the client
  (Chrome web browser)
- the ftpalias.cfg file was left open in some instances

being CWD'd (chdir'd) into.
I resisted the temptation to convert ftpalias.cfg to a different (sane)
format (e.g. .ini) at this time, but that really should be done.
Oh, and I noticed that aliases don't work with "DIR" wildcards, so that's a
bug that needs fixing too.

- user alias was missing from some messages or in the wrong place
- added hostname and IP address to the "ILLEGAL FILENAME ATTEMPT" warnings

with Chrome (the browser). Chrome will attempt to "CWD" to a filename and if
that filename was an alias from the ftpalias.cfg, we would return a
successful (213) response - erroneously. The code did appear to check for
this condition by calling ftpalias() with a NULL second (filename)
parameter, but that didn't actually work. The 'alias+1' check for a slash
appears to have (always?) been clearly wrong as a prefixed slash is already
skipped (in the requested path) before calling ftpalias().

Double the duration to wait for client threads to terminate. Heck, this might
should be an infinite wait since "bad things" happen if the client thread
continues after a cleanup().

with the terminal and mail servers' log output and provide more details
(e.g. on errors).

left-justified server prefix), e.g. "term" now added for terminal server
errors.

you can't print and free it again after calling that macro.

and send_mlsx().
Fix numerous printf-style argument bugs, many in the TLS and MLSx support.

Put "TLS" in the failure log messages rather than repeating "FTP".