Add SessionSetup to EV side state machine

[cienporcien]

Describe your changes

Add SessionSetup to EV side state machine

Issue ticket number and link

#138

Checklist before requesting a review

• [ x] I have performed a self-review of my code
• I have made corresponding changes to the documentation
• [ x] I read the contribution documentation and made sure that my changes meet its requirements

[SebaLukas]

Check my comments.

Plus for the session_setup state:

At the moment, it is sufficient if the EV does not support pause/resume.
Pause/resume can be added relatively easily afterwards.

I have roughly written down how I imagine the process in this state:

1. Check ResponseCode -> Evse old session joined or OK_NewSession
2. Check session id -> like validate_and_setup_header() in https://github.com/EVerest/libiso15118/blob/main/src/iso15118/d20/context_helper.cpp#L30
3. Check if the chargers wants to join an old session with the response code and not with the ctx session session_id
   -> Check Cert session id hash
4. Create Req
   -> AuthSetupReq or
   -> Ac/DcChargeParameterDiscovery

[SebaLukas]

In this case the ev can also go to AuthSetup and treat this as a new session

[cienporcien]

This isn´t clear to me in the standard.

From this it appears that the session should be terminated.

[SebaLukas]

I guess the standard mean terminating the old session. And starting a new one.
I think in this case the ev should start a new session. The charger should handle this.

[SebaLukas]

I have roughly written down how I imagine the process in this state:

1. Check ResponseCode -> Evse old session joined or OK_NewSession
2. Check session id -> like validate_and_setup_header() in https://github.com/EVerest/libiso15118/blob/main/src/iso15118/d20/context_helper.cpp#L30
3. Check if the chargers wants to join an old session with the response code and not with the ctx session session_id
   -> Check Cert session id hash
4. Create Req
   -> AuthSetupReq or
   -> Ac/DcChargeParameterDiscovery

@cienporcien Did you check my last reply?

[cienporcien]

I have roughly written down how I imagine the process in this state:

1. Check ResponseCode -> Evse old session joined or OK_NewSession
2. Check session id -> like validate_and_setup_header() in https://github.com/EVerest/libiso15118/blob/main/src/iso15118/d20/context_helper.cpp#L30
3. Check if the chargers wants to join an old session with the response code and not with the ctx session session_id
   -> Check Cert session id hash
4. Create Req
   -> AuthSetupReq or
   -> Ac/DcChargeParameterDiscovery

@cienporcien Did you check my last reply?

Hi Sebastian,
Sorry, I didn´t read this carefully enougn. I have made the change to use the response code instead of the ctx session_id.