[squid-dev] [PATCH] Invalid FTP connection handling on blocked content

[Christos Tsantilas]

Hi all,
  this patch waits for long time in queue.
If no objection I will apply this patch to trunk.


On 12/29/2015 06:31 PM, Christos Tsantilas wrote:
>
> Problem description
> --------------------
>
> FTP client gets stuck after the following chain of events:
>
>   * Client requests a file that will be blocked by ICAP.
>
>   * Squid starts downloading the file from the FTP server and sends "150
> Opening..." to the FTP client.
>
>   * Squid aborts the data connection with the FTP server as soon as the
> ICAP service blocks it.
>
>   * Squid sends "451 Forbidden" to the FTP client.
>
>   * The FTP server sends "500 OOPS: setsockopt: linger" to Squid.
>
>   * Squid terminates the control connection to the FTP server.
>
>   * Squid establishes a new control connection to the FTP server but
> does not authenticate itself.
>
>   * Further commands from the FTP client do not work any more.
>
> The above and many similar problems exist because Squid handles FTP
> client-to-squid and squid-to-FTP server data connections independently
> from each other. In many cases, one connection does not get notified
> about the problems with the other connection.
>
> Tech details
> ------------
>
> This patch:
>    - Add Ftp::MasterState::userDataDone to record received the FTP
> client final response status code to sent (or to be send) to the client.
>
>    - The Ftp::MasterState::waitForOriginData flag to hold status of the
> squid-to-server side. If the squid-to-server side is not finishes yet
> this is true.
>
>    - Send a control reply to the FTP client only after the data
> transferred on both server and client sides.
>
>    - Split Client::abortTransaction to Client::abortOnData and to
> Client::abortAll()
>
>    - Implement the Ftp::Relay::abortOnData() and Ftp::Relay::Abort()
> (i.e., StoreEntry abort handler) to avoid closing the control connection
> when the data connection is closed unexpectedly.
>
> This is a Measurement Factory project.