Peter M. Groen / FlashMQ

This also contains some fixes/unifications for traditional
authentication, error handling specifically.

Also fix some bugs:

- The password can be binary data.
- The will topic is now also checked.

It went over boundry when there were no properties.

Also changed will logic in disconnect: only clear it when it's a
successful disconnect.

And the TODOs are for the next thing: saving the createdAt date.

This prevents bugs because the calling context forgets it. A (small)
downside is that I have to make the Publish argument non-const. But,
that's exactly what it is then, so...

Also fixed a length check bug.

Because clients can now also exist as dummy objects, I had to add some
extra checks.

Also split up handlePublish() and the new parsePublishData().

I'm not sure how I'm continueing. I need a safe point.

I'm simplying/merging the rec, comp and rel packets, but I'm not sure it will
work. Committing as a safe point.

Later: I got it done as planned. Testing qos > 0 and mqtt5 still needs
to be done more.

And one line about correlation data that was a bug.

I need to decide what to do with getPublishData

and that disabled test needs repurposing.

which also has implications on how I think to handle 'queuePacketAtSub'

Most of it is limits we already implemented non-standard compliant.

For the coming MQTT5 support, I'll need this a lot.

This is a preparation for MQTT5, because when there are receivers and
publishers with different protocols, you can't always just write out the
same packet. You can sometimes though, so that's what the copy factory
determines.

This entails making copies of the original packet when necessary,
because QoS 0 doesn't have a packet id. I tried to keep it to an
absolute minimum and do some precarious optmizations for it. There are
tests though.

This makes more sense, logically, and also helps in tests I'm about to
write.

It caused typical global variable issues, showing in the retained
messages recursive alghorithm breaking, because the referenced subtopics
changed half way (see previous commit of the test for it).

I need to perform some benchmarks to see if I need to devise an
alternative.

Files are simple serialized bytes prefaced by lengths. File is hashed to
verify integrity. This was also a good way preventing unexpected errors
when trying to crash the parser by having it load a different file.

This change includes some refactoring that was necessary:

- It 'fixes' looking at the wrong thread's authentiction. This is still
  wrong though. It will be fixed by a thread local pointer in the next
  commit.
- Deadlocks with yourself are handled in rwlockguard.
- QoSPacketQueue is now a class.
- Probably other tweaks.

Shifting signed integers is undefined and only sometimes produced
unexpected results.

Was detected in packet identifiers in QoS testing.

My IDE didn't understand them for finding symbols, apparently.

This allows creation of multiple listeners, with different protocols
and/or SSL certificates.

Related change: settings is now a class that is copyable and assignable,
and is done so to each thread on reload.

Semi-related fix: fix crash in quit when multiple threads initiated it.
This came to light when testing the auth plugin settings.

And some side issues.

Also includes fixes to packet parsing that I couldn't make a separate
commit for.

When it comes to QoS 1, these things are still left, off the top of my
head:

- vector for qos queue? It helps with ordering and is CPU cache friendly.
- Store subscription QoS.
- Do retained messages have QoS?
- Give session client's name, to access it later.