func()

in sasl.go [197:242]

• 38 lines of code
• 8 McCabe index (conditional complexity)

func (s saslXOAUTH2Handler) step(ctx context.Context) (stateFunc, error) {
	// read challenge or outcome frame
	fr, err := s.conn.readFrame()
	if err != nil {
		return nil, err
	}

	switch v := fr.Body.(type) {
	case *frames.SASLOutcome:
		// check if auth succeeded
		if v.Code != encoding.CodeSASLOK {
			return nil, fmt.Errorf("SASL XOAUTH2 auth failed with code %#00x: %s : %s",
				v.Code, v.AdditionalData, s.errorResponse)
		}

		// return to c.negotiateProto
		s.conn.saslComplete = true
		return s.conn.negotiateProto, nil
	case *frames.SASLChallenge:
		if s.errorResponse == nil {
			s.errorResponse = v.Challenge

			timeout, err := s.conn.getWriteTimeout(ctx)
			if err != nil {
				return nil, err
			}

			// The SASL protocol requires clients to send an empty response to this challenge.
			err = s.conn.writeFrame(timeout, frames.Frame{
				Type: frames.TypeSASL,
				Body: &frames.SASLResponse{
					Response: []byte{},
				},
			})
			if err != nil {
				return nil, err
			}
			return s.step, nil
		} else {
			return nil, fmt.Errorf("SASL XOAUTH2 unexpected additional error response received during "+
				"exchange. Initial error response: %s, additional response: %s", s.errorResponse, v.Challenge)
		}
	default:
		return nil, fmt.Errorf("sasl: unexpected frame type %T", fr.Body)
	}
}