On Sun, 14 Jul 2013, Clemens Gruber wrote:

> I am using the newest version 7.31.0.
>
> You are right, it¢s a very old ftp server from OS-9, but because SIZE is not
> in the FTP RFC (959), the client should not depend on it. PASV is also not
> supported on this server.

... and yet PASV _is_ in RFC959! =)

> I now have two capture files for you (zipped):
> http://178.189.19.236:8080/curl_ftp.zip

Thanks. It does indeed hint on something weird going on in libcurl. My current
thinking is that the problem is like this:

1 - ftp_state_get_resp() gets called to handle the response to RETR (a 150)

2 - it deems the response to be fine, and since a PORT connection has been
     requested it allows the server to connect with a call to
     AllowServerConnect()

3 - the connection is "instant" and the code around line 2550 then doesn't
     properly change state

4 - when using verbose output, libcurl is slower and thus it probably isn't
     "instant" and thus the code flow changes somewhat and everything is dandy

I don't yet understand how this then triggers a second SIZE command, but it
will at least end up in a funny state.

I'm thinking a decent fix could look like this and I'd be happy to hear your
results or thoughts:

diff --git a/lib/ftp.c b/lib/ftp.c
index 5d78ad6..78cdb0c 100644
--- a/lib/ftp.c
+++ b/lib/ftp.c
@@ -2551,6 +2551,8 @@ static CURLcode ftp_state_get_resp(struct connectdata
*conn,
          state(conn, FTP_STOP);
          ftpc->wait_data_conn = TRUE;
        }
+ else
+ return InitiateTransfer(conn);
      }
      else
        return InitiateTransfer(conn);

-- 
  / daniel.haxx.se

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Received on 2013-07-14