Many searches are done (e.g. in the mail server, QWK import) for either of 2
strings in single file or list, so let's optimize that to a single iteration
through the file/list. This should reduce some redundant file I/O.

I do find this API a little confusing with the filename or list at the end
of the argument list, but kept it consistent with the existing single string
findstr functions (which are now just wrappers for the new 2-string flavors).

I noticed during this update that findstr() did not share the same behavior
as findstr_in_list() (feature added in commit f08f2137) whereby if all the
patterns were negative searches (beginning with '!'), then *all* the
negative matches would have to be successful (not just the first) for the
function to return true. So now findstr() behaves like findstr_in_list()
in this regard.

I also added some optimizations to findstr_in_string().

Using "Warning" log levels more for things that the sysop might be able to do
something about. If it's just an input data validation (from a random TCP/IP
client), use "Notice" log level instead.

The terminal server log output is still the odd ball.

The time span over which consecutive failed logins are attempted is important

'@' is in the name.can by default and the mail server recognizes user@addr
formatted logins/attempts, so truncate at the '@' before comparing against
the name.can file to prevent false !TEMPORARY BAN (1 login attempts, ...
occurences.

The log format and details might need some adjustment, but this is a start.

Also, don't delay 3 seconds before disconnecting socket when mail server has
reached maximum number of clients - we should immediately release resources
(the socket) and be able to accept another connection ASAP instead.

Deal with new CID 470557 and 470554 in mail server: resource (file*)
leaks in error paths (corner case).

Set minimum severity of TLS messages in web sever to INFO. Debug-level would
hide some common TLS session errors.

That's percent minus, to go with percent plus (user's real name).

The string is auto-quoted if it contains a space.

For Keyop's use with rlogin.js, maybe.

When a JS environment (e.g. server, jsexec) is terminated, it's possible
that a require() script was being evaluated. But since termination would
abort that evaluation, it's not unexpected if a symbol ends up not being
defined before the require() script was terminated, so don't report an
error in that case.

Fix issue #681

The base64-encoded credentials can either be supplied with the AUTH PLAIN
command or in response to a 334 server-challenge. We only supported the
former form and logged a warning ("Missing AUTH PLAIN argument") when we
received the latter. No warning is logged now and the appropriate
server-challege is sent and the response accepted and base64-decoded and
parsed as before.

And fix some use of CRYPT_UNUSED instead of cryptlib session ID.

Attempt to fix issue #680

This probably will need some llvm or other exceptional handling for
non GNU build systems.

Since we're logging at INFO level when the connect is attempted, we can assume
success when we start logging additional init messages.

These can always be revived from the attic if there's some need or purpose.

My mail server was suddenly and inexplicably creating thousands of SMTPS
client threads, each with a unique remote IP address, and each eventually
failing with the rather obscure log message (from cryptlib):
 dbg 'Cannot read item from object' (-41) setting session active

Eventually (after not long, really), the server would run out of resources
and fail in weird and wonderful ways (can't malloc, can't create JS runtime
or context, etc.). The max_clients limit (100, as I have it set) wasn't being
effectively-imposed on SMTPS connections.

The root-cause: the active_clients (counter) wasn't incremented until *after*
the cryptlib/TLS setup for SMTPS connections and SMTPS/TLS connections can
take a long time to fail, resulting in a vulnerability to an effective denial
of service attack.

Raise the minimum severity of all cryptlib/TLS log messages from Debug to
Info.

Create wrappers for smtp_thread() [now smtp_client_thread()] and pop3_thread
[now pop3_client_thread()] that handle basic resource management (thread
counters, active client counters, the client socket).

... in malloc error reporting messages

We need to call mqtt_shutdown() instead of mqtt_close() to have the mosquitto
(loop) thread stopped.

Upon connect failure, call the mqtt_shutdown() *before* calling lprintf->lputs,
which would eventually try to MQTT-publish the log message.

The call to mqtt_connect() can block for a while, so raise the log severity
of the "connecting to broker" message from DEBUG to INFO. Otherwise, a bad
MQTT broker address or port would make the servers just appear to hang during
initialization, for no reason.

Fixes issue #679

CryptCert.export_cert(CryptCert.FORMAT.TEXT_CERTIFICATE) should
now work properly instead of always returning an error.

That doesn't trigger a Coverity defect this time (CID 470457)

Actually tested myself this time, needed a lot more than first appearances.

Also includes a security/safety enhancement where the @-code expanded string
is *not* used as an sprintf format string. Supporting both format specifiers
and @-codes in a single text.dat string is tricky (always has been).

For Accession.

resulting from commit 5f1c39f0

Fix for issue #678

The first word of the message recipient or author's name.

For Accession.

Expected to use the MSG_* @-codes in this context. This allows more freedom
of ordering the message header fields reused in this expanded string. The %s
specifiers can be eliminated altogether when using @-codes.

For Accession to play with.

With 0xE0 being used for ciolib "super-extended scancodes", a literal
0xe0 can't pass through the input path.  This is an issue in CP866 (р)
and KOI8-U (Ю) as well as CP437 α.

Should fix SyncTERM SF bug 123.

of sbbs_t::external()

The startup directory for DOS doors might not be a valid Unix (case-sensitive)
path, so let's just do that check in the native block here.

Also, removed a bunch of redundant startup_dir ==/!= NULL checks. It can't be
NULL here.

The '-l' (loop) option would cause the JS runtime to be destroyed and
recreated for each new execution of the script, which resulted in memory
leaks in Windows builds (see issue #672 for details). So instead, just
use a single JS runtime here when the -l option is used to prevent that
from happening, though truth be told, that's likely not a normal/common
occurrence. Other apparent JS-related memory leaks (e.g. in the web
server) appear to be of a common concern.

Likely upgrading to a modern libmozjs would also fix this issue, but
we're far short of being able to do that right now.

This reverts commit cfcff881

... to de-clutter the log

Also, don't log the packet passwords. Folks copy and post sbbsecho.log lines
and that could seriously compromise the security of the Interwebs if those
super-secret passwords were ever leaked!

Previously, any packets created for unlinked nodes, would always be Type-2
packets and the packet type for newly created nodes (in echocfg->Linked Nodes)
would be Type-2+.

The new DefaultPacketType setting default is 2+, so the only observed
change in behavior will be that packets created for unlinked nodes will also
be type 2+ (by default).

Some additional log detail/adjustment around created/detected packet types.

Introduced in commit 0e38cb0f (9 months ago), the first linked-node config
(including packet password!) for the first packed netmail message would be
reused for subsequent packed netmail messages.

Thank you to Wilfred van Velzen (2:280/464) for reporting this problem!

Additional debug-level log message when using a packet password for a newly
created packet.

Since SYMLINK=1 is valid/suggested for install/GNUmakefile, this is a common
mistake that we can catch here.

'T' command from the reading messages (O)perator menu

Abstraction the twit-list usage.