lib/omniauth/strategy.rb
def call!(env) # rubocop:disable CyclomaticComplexity, PerceivedComplexity
      unless env['rack.session']
        error = OmniAuth::NoSessionError.new('You must provide a session to use OmniAuth.')
        raise(error)
      end

      @env = env
      @env['omniauth.strategy'] = self if on_auth_path?

      return mock_call!(env) if OmniAuth.config.test_mode
      return options_call if on_auth_path? && options_request?
      return request_call if on_request_path? && OmniAuth.config.allowed_request_methods.include?(request.request_method.downcase.to_sym)
      return callback_call if on_callback_path?
      return other_phase if respond_to?(:other_phase)

      @app.call(env)
    end
def call!(env) # rubocop:disable CyclomaticComplexity, PerceivedComplexity
      unless env['rack.session']
        error = OmniAuth::NoSessionError.new('You must provide a session to use OmniAuth.')
        raise(error)
      end

      @env = env
      @env['omniauth.strategy'] = self if on_auth_path?

      return mock_call!(env) if OmniAuth.config.test_mode
      return options_call if on_auth_path? && options_request?
      return request_call if on_request_path? && OmniAuth.config.allowed_request_methods.include?(request.request_method.downcase.to_sym)
      return callback_call if on_callback_path?
      return other_phase if respond_to?(:other_phase)

      @app.call(env)
    end
The logic for dispatching any additional actions that need
 to be taken. For instance, calling the request phase if
 the request path is recognized.

 @param env [Hash] The Rack environment.