R2: Fix JSONRPC Version() bug

[risingPhil]

Problem:

When following the example code described here:
https://rdkcentral.github.io/rdkservices/#/userguide/native?id=creating-native-clients

If I perform the "DeviceInfo.defaultresolution" request with callsign "DeviceInfo", I'm getting an error:
"Requested version is not supported".

But I also get this when trying other rdkservices APIs (for example: org.rdk.Bluetooth.getApiVersionNumber)

Root cause:

WPEFramework sends out the request like this:

{"jsonrpc":"2.0","id":1,"method":"DeviceInfo.0.defaultresolution","params":{}}

As you can see, it added a versionnumber '0' to the method parameter.

Bug:
When the example scenario is triggered as described above, WPEFramework::Core::JSONRPC::Version() is called with "DeviceInfo." as designator.

At the if-statement with the atoi statement, index remains at pos - 1 and therefore points to the 'o' character. Because index < pos, result would be set to the result of the atoi() call.

But as described here: https://cplusplus.com/reference/cstdlib/atoi/#google_vignette

If the string starts with an invalid integral number, atoi() will return 0.

Because the result of WPEFramework::Core::JSONRPC::Version() is no longer 0xFF, the _versionstring field of JONRPCLink gets set to ".0". This in turn causes it to get appended to the method field of the jsonrpc request.

Fix:

Make sure to add an isdigit() check before trying the atoi() call. If !isdigit(), the atoi() call is now being avoided.

The WPEFramework::Core::JSONRPC::Version() code has been changed in the master branch. But for RDK 6.0.0, the R2 branch of Thunder is still being used by default.

I therefore think it's likely this fix will only be needed for R2-based versions.

[risingPhil]

By the way: here is a test application I wrote to test this scenario alongside a recipe.

You may have to edit the recipe to fit your personal folder path (externalsrc based). I have personally been building RDK using a docker container.

testapp.tar.gz

To use this test application from the terminal (over SSH on a raspberry pi):

rdkjsonrpc 127.0.0.1:9998 DeviceInfo defaultresolution

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[pwielders]

@risingPhil good catch! Indeed on master the code is heavily changed but looks like there the check for IsDigit is done. Guess this is an R2 issue only!

[risingPhil]

Thanks! ;-)