OAuth 2.0 Token for Windows Client

The DLL function is implemented in C# as an OAuth 2.0 authorization flow using the authorization code grant type. The OAuth parameters required for the OAuth function, such as oauthUrl, clientId, redirectUrl and scope, are read by the function from an appsettings.json file. To increase security, a CodeVerifier and a CodeChallenge are created for the PKCE extension of OAuth 2.0. The OAuth Url is then called asynchronously with all the necessary parameters and a browser is started, which waits for a response using the transferred redirectUrl. Once the response has been received, it is checked again for the CodeChallenge and the status. If everything is correct, the actual OAuth Url for retrieving the access token and the refresh token is called and returned a .json file.