The state confusion and response code garbling issue caused by the LIST command

[Wang-jiong-han]

I attempted to test LightFTP using state machine learning technology and found that for the LIST command, if no data connection is established, the server may enter an abnormal state with a certain probability. In this state, the server can receive commands normally but returns garbled response codes. You can refer to the attached state machine diagram below for specific request-response details. I tested this on the old version (5980ea1), the latest release (9a6128d), and the latest commit (d40233b), and the issue persists across all versions.