[php] Session saves SMS verification code.

Dude, conversations are automatically generated. When you connect to the server, you will have a session_id, and each user's id is unique. Or create a session for each user to save the verification code? From this sentence, you know that you haven't understood this yet ... just save it directly, and users can only read their own ID sessions. Cancel this. You can set the life cycle on the server or not. If you close the connection, you will log yourself out.