LIST command in Pop3 server-like

Question

I must do a pop3 server in bash and I have a problem with the LIST command. I can connect to my server, do some command but when LIST are calling my client wait long time. He probably wait for another input but I can't see what I'm doing wrong.

I follow the [RFC 1939][1] :

C: LIST
S: +OK 2 messages (320 octets)
S: 1 120
S: 2 200
S: .

My minimal implementation :

[...]
"STAT"*)
    echo "+OK 1 3"
    ;;
"LIST"*)
    echo "+OK 1 messages (3 octets)"    
    echo "1 3"
    echo "."
    ;;
[...]

Claws Mail Log :

* Account '[email protected]': Connecting to POP3 server: localhost...
[18:02:42] POP3< +OK
[18:02:42] POP3> USER root
[18:02:42] POP3< +OK USER
[18:02:42] POP3> PASS ********
[18:02:42] POP3< +OK PASS
[18:02:42] POP3> STAT
[18:02:42] POP3< +OK 1 3
[18:02:42] POP3> UIDL
[18:02:42] POP3< -ERR 'UIDL
' n'est pas une commande valide
** command not supported
[18:02:42] POP3> LAST
[18:02:42] POP3< -ERR 'LAST
' n'est pas une commande valide
** command not supported
[18:02:42] POP3> LIST
[18:02:42] POP3< +OK 1 messages (3 octets)
// HERE WAIT A LONG LONG TIME //
** Session timed out. You may be able to recover by increasing the timeout value in Preferences/Other/Miscellaneous.

Thank you. [1]: https://www.rfc-editor.org/rfc/rfc1939#page-6

Answer 1

Try making sure each line of your responses ends with CRLF, not just LF. It might be that just the commands expecting a multi-line response insist on seeing .CRLF, not just .LF.

[...]
"STAT"*)
    printf "+OK 1 3\r\n"
    ;;
"LIST"*)
    printf "+OK 1 messages (3 octets)\r\n"
    printf "1 3\r\n"
    printf ".\r\n"
;;
[...]