Add basic SSL support for micropython

[fgervais]

This is a partial support as the CA certificate is not validated. This is so as this functionality is not implemented in all micropython ports.

For example, it isn't currently supported in the esp32 port although a draft of the feature has been published: https://github.com/micropython/micropython/pull/5998

As the CA functionality is not there, we cannot use this parameter do decide when to switch to SSL mode as done in the CPython version. Instead we enable SSL when connecting to port 443 or 8443 which are well known ports used for TLS communications.

One more thing is that this library relies on short reads to get data from the socket as it always ask for the max buffer length when reading. In micropython, the interface provided for SSL socket is only the one of a stream which doesn't allow short reads. To go around this we change the socket to non blocking which has the side-effect of allowing short reads. However we then need to do manual polling and timeout on the socket which we do here.

[antohaUa]

François, let's do NOT forget about users and well know python Zen aphorisms "Simple is better than complex" "Although practicality beats purity"

I know that it is just philosophy but ...

If iamgine that we use pure cPython your solution looks great and I always raise both hands for classes inheritance libraries patterns etc But for micropython we have a little bit other things - resource limitations and not so good documentations, not supported modules ...

User frequently frustrated even with single lib installation procedure. What to talk about complex scenarion with two libs and inheritance + running script So my position still the same - we should leave CPython and micropython libs as is for backward compatibility and do not affect user experience. SSL micropython lib I suggest to add as separate library. Within this lib we can cut all functional related to NON ssl connections etc. Main goal small ssl oriented micropython lib - users if they want ssl and have support of ussl will be able to use it.

I know there will be code duplication maybe sync issues etc - but this is mycropython )) It is just on the way for stabilization/standartization Hope after 1-2 year all will be synced and for example ussl port will be everywhere.

As so-author of course put your copyright to new ssl module and let's start use it. Waiting for your final commit - hope my arguments will be accepted by you. Thx in advance.

[fgervais]

I'm not sure I understand.

So my position still the same - we should leave CPython and micropython libs as is for backward compatibility and do not affect user experience.

With the current PR they are the same. The micropython library work the same internally and is used the same way. No backward compatibility problem.

It is still used as shown in README.md i.e.

import blynklib_mp as blynklib

blynk = blynklib.Blynk(BLYNK_AUTH)

Also the micropython lib does not import anything new.

There is a small new blynklib_mp_ssl.py library as you requested.

I feel the PR as it stands is well aligned with you requests.

[antohaUa]

To be honest schema provided by you will work ... but we add additional complexity into existing mp library without enhancing it's functionality just increasing it's size that also may be critical for low memory systems.

New SSL oriented separate module will give more profit: All users from the beginning know if their HW supports ussl and is they want to use ssl connection. So they simply will choose what lib should be written to HW memory common MP module or MP ssl module.

Yeap we have code duplication - but I am temporary ok with this - want to wait untill ussl will be accepted and used across all new HW. Until this time SSL lib for micropython is just POC or prototype - better to place it as separate module without modifying existing libraries.

[fgervais]

Alright I see your position.

I'm sorry I cannot comply with these requests.

This PR can be dismissed, thank you.

[antohaUa]

François, sorry from my side also - lib active development was finished by me year+ ago. Thus main focus for now only stability and support. Sometimes this can block new features ... Anyway as I said previously thanks for your investigation and contribution - hope WE can be lucky with next PRs acceptance.

For now I will leave this branch - it might be useful for users.