TLS support with WolfSSL

[shantanu1singh]

I noticed that the CMakeLists.txt file currently looks for OpenSSL if TLS is enabled

IF (MQTT_USE_TLS)
    FIND_PACKAGE (OpenSSL REQUIRED)
    IF (MQTT_USE_STATIC_OPENSSL)
        FIND_PACKAGE (ZLIB REQUIRED)
    ENDIF ()
ENDIF ()

Now that it's possible to compile Boost Asio with WolfSSL, can mqtt_cpp also support WolfSSL as the TLS library instead of OpenSSL? From what I can see, mqtt_cpp currently only depends on boost::asio::ssl and not OpenSSL directly. Is that correct?

[jonesmz]

I believe this is correct.

If you submit a PR that keeps existing compatibility while allowing the WolfSSL to work as a configure option, it would probably be merged.

Please include continuous integration testing for it as well.

[shantanu1singh]

Thanks @jonesmz

I'm currently occupied with work. Will send a PR once I have something ready.