SSL support for MQTT connection

[kleini]

This is stolen from timpur's v2.1 branch.
I like to encrypt my MQTT connections because passwords are transmitted over MQTT in clear text. Passwords transmitted in clear text should be always avoided.

[timpur]

Just double check my change for the Mac string

homie-esp8266/src/Homie/Limits.hpp

Line 13 in 48e8fab

const uint8_t MAX_MAC_LENGTH = 6;

:P

[amayii0]

Just a very generic comment, I'm not following heavily the dev but looking here and there.
Would be great if consts are commented with a sample value, from this, how are you storing MAC?

[kleini]

Up to this point I only picked some commits. Will read and try to verify the code now.

[kleini]

@timpur I hope I fixed all char array and string length.

[timpur]

Looks good (I believe these changes were in 2.1) ?

[kleini]

Just to mention it, because I stumbled again over it:
ASYNC_TCP_SSL_ENABLED requires PIO_FRAMEWORK_ARDUINO_LWIP2_HIGHER_BANDWIDTH otherwise the SSL connections do not work at all.

[timpur]

Just to mention it, because I stumbled again over it:
ASYNC_TCP_SSL_ENABLED requires PIO_FRAMEWORK_ARDUINO_LWIP2_HIGHER_BANDWIDTH otherwise the SSL connections do not work at all.

Maybe @kleini document that ?

[kleini]

@timpur documented SSL connections for MQTT.

[bodiroga]

Should we merge this PR in the 'develop' branch or the 'develop-v3' branch? IMHO, we should leave 'develop' only for bugfixes and add new features to 'develop-v3' 😉

[kleini]

Yes, will rebase my work on develop-v3 the next days.

[stritti]

Yes, will rebase my work on develop-v3 the next days.

@kleini could you rebase it to be merged then?

[kleini]

I rebased my work on develop-v3. The build is broken because of the resulting image size. Will try to check, why the image size is limited this way.

[bodiroga]

Great work Markus!

[kleini]

@bodiroga This is not my work. @timpur implemented this and I just try to get it merged as I consider encryption for MQTT connections as essential (clear text passwords).