From: Shugo Maeda <shugo@...>
Date: 2010-01-06T14:32:50+09:00
Subject: [ruby-core:27440] Re: [Bug #2554] Net::FTP should not use MSG_OOB

Hi,

2010/1/6 Tanaka Akira <akr@fsij.org>:
>> The FTP protocol description does not seem to make any mention that the ABOR command should be sent with MSG_OOB. This makes be believe that Net::FTP is bugged, not the server.
>
> Although FTP (RFC 959) doesn't mention OOB, the control connection follows
> Telnet Protocol and TELNET (RFC 854) uses TCP Urgent notification.
>
> I don't know the details of FTP and TELNET, though.

In page 34 to 35 of RFC 959, it is described as follows:

   FTP commands may be partitioned as those specifying access-control
   identifiers, data transfer parameters, or FTP service requests.
   Certain commands (such as ABOR, STAT, QUIT) may be sent over the
   control connection while a data transfer is in progress.  Some
   servers may not be able to monitor the control and data connections
   simultaneously, in which case some special action will be necessary
   to get the server's attention.  The following ordered format is
   tentatively recommended:

      1. User system inserts the Telnet "Interrupt Process" (IP) signal
      in the Telnet stream.

      2. User system sends the Telnet "Synch" signal.

      3. User system inserts the command (e.g., ABOR) in the Telnet
      stream.

      4. Server PI, after receiving "IP", scans the Telnet stream for
      EXACTLY ONE FTP command.

Then, ncftp seems to send the IP and Sync singals with MSG_OOB before
sending ABOR without MSB_OOB.
Should I fix Net::FTP in a similar way?

-- 
Shugo Maeda