Also:

* Update to alpine:3.12.
* Use openssl.
* Enable TLS-PSK.
* Remove obsolete 1.4.12 dockerfile.

This only occurs when compiled without epoll support.

Closes #1700. Thanks to Matthias Urlichs.

We currently erroneously claim that mosquitto_lib_init cannot fail,
while it can fail on Windows, if WSAStartup fails in net__init. Correct
this.

Signed-off-by: Martin Kelly <mkelly@xevo.com>

Add a refcount around mosquitto_lib_init and mosquitto_lib_cleanup so
that multiple calls to init/cleanup don't trigger memory leaks or
double-frees.

Signed-off-by: Martin Kelly <mkelly@xevo.com>

Closes #1684. Thanks to grekhss.

Closes #1674. Thanks to amigian74.

This prevents the session expiry being extended on SIGHUP.

Closes #1521. Thanks to Christoph Krey.

Closes #1664. Thanks to Leon Kiefer.

Port 9001 is used by Intel drivers on Windows, so some users are
suddenly seeing a problem.

Issue #1580.

Issue #1653.

Rather than letting the bridge fail later.

Issue #1635. Thanks to pokerazor.

Issue #1641.

Issue #1629. Thanks to radcrabs.

Plus add missing header.

This patch changes the behavior of how mosquitto is starting using
systemd.

Currently it is starting only when the network is online, meaning that the
network is configured to a routable IP address.

With this patch, mosquitto is starting when the network is offline, does
not need to be configured. This is needed because the MQTT broker might
be used as an internal message bus which does not need the network to be
online.

Signed-off-by: Stavros Vagionitis <stavros.vagionitis@jci.com>

Since all resources are ready, do not need lookup again.

Signed-off-by: Michael Liu <michael.liu.point@gmail.com>

WebSocket context may lost since db->ll_for_free = NULL; operation on the bottom of context__free_disused() function.

Signed-off-by: Michael Liu <michael.liu.point@gmail.com>

Closes #1614. Thanks to Christoph Krey.

Closes #1622.