PQ56305: FTSUTL050I SEND REPLY 'UNKNOWN MESSAGE NUMBER XXXXXX'

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• FTP Client is using PASV to open a passive connection. In the
  case when the connection was not used because of a failing
  situation (where a failing reply code was sent back to the
  client), an extra reply was being sent to the client when the
  passive connection closed. Traces showed messages:
  FTSUTL050I Send reply '550 'SFSPOOL1 yyy'  not found'
  FTSUTL050I Send reply 'Unknown message number 538568
  

Local fix

• MT02922
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: All z/VM FTP server users using PASV         *
  *                 support.                                     *
  ****************************************************************
  * PROBLEM DESCRIPTION: Problems occur in the z/VM FTP server   *
  *                      when processing passive data            *
  *                      connections (initiated with the FTP     *
  *                      client PASV command).                   *
  ****************************************************************
  * RECOMMENDATION: APPLY PTF                                    *
  ****************************************************************
  When an FTP client uses PASV to open a passive connection and
  the connection is not used because of a failing situation
  (where a failing reply code is sent back to the client), the
  z/VM FTP server sends an extra reply ('Unknown message number
  nnnnnn' (where nnnnnn is a number)) to the client when the
  passive connection closes.  This causes the client and server
  to be out of sequence with each other.  The problem occurs in
  the DataReply() procedure in FTSUTIL PASCAL, which is called to
  send the reply to the command that needed the data connection.
  At the time DataReply() is called in a failing situation, the
  unsuccessful reply has already been sent to the FTP client and
  the CmdInProgress field in the control connection structure has
  already been set to CUNKNOWN.  The DataReply() procedure
  contains no logic to see if a reply has already been sent, and
  it also contains no logic to handle an unknown command.  So the
  message number used in the reply is never set causing the
  message number field to be garbage which causes the message
  compiler to return the 'Unknown message number nnnnnn' reply,
  which is sent to the client.
  
  An additional problem occurs in the z/VM FTP server if an FTP
  client attempts to follow a client initiated data transaction
  (using the PASV command) with a server initiated data
  transaction (using the PORT command).  In this case, the FTP
  server will disregard the PORT command and wait for the client
  to initiate the data connection.  This problem occurs because
  the BeActive field in the control connection structure (which
  indicates whether the FTP server should initiate a data
  connection) is not reset (after the PASV connection is
  processed) to indicate a default of an FTP server initiated
  data connection (given in the File Transfer Protocol RFC
  (959)).
  

Problem conclusion

• The z/VM FTP server was changed to not send a reply in the
  DataReply() procedure if the CmdInProgress is CUNKNOWN.  Since
  the CmdInProgress has been set to CUNKNOWN when a failing
  situation occurs, the FTP server no longer sends an extra
  reply to the FTP client.
  
  In addition, the z/VM FTP server was changed to default to an
  FTP server initiated data connection after a client initiated
  data connection is processed by setting the BeActive field on
  when the passive data connection closes in CloseCompletedEvent
  in FTSEVEN PASCAL.  This allows the FTP server to successfully
  process both client and server initiated data connections in
  any order.
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

  UQ64188 UQ64189 UQ64190 UQ64191

Modules/Macros

• FTSEVEN  FTSUTIL  MSFTP    SRVRFTP
  

Fix information

• Fixed component name

  TCP/IP V2 FOR V

• Fixed component ID

  5735FAL00

Applicable component levels

• R3A0 PSY UQ64188

     UP02/03/21 P 0402

• R320 PSY UQ64189

     UP02/03/21 I 1000

• R410 PSY UQ64190

     UP02/03/21 I 1000

• R420 PSY UQ64191

     UP02/03/21 P 0303

Fix is available

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