IY93752: EXCESSIVE DNS LOOKUPS

WebSphere MQ V6.0 Fix Pack 6.0.2.2
WebSphere MQ V6.0 for iSeries Fix Pack 6.0.2.2
WebSphere MQ V5.3 and WebSphere MQ Express V5.3 - Fix Pack 14 (CSD14)
WebSphere MQ V5.3 for iSeries - Fix Pack 14 (CSD14)

APAR status

• Closed as program error.

Error description

• MQ/GSKit is causing a loop when a socket closes unexpectedly.
  Trace shows that the GSKit ccigsk_secure_sock_read calls a tcp
  routine (cciTcpSslReadCallback).  This is expecting a return
  code and errno but MQ is only setting the return code.  This
  causes it to retry after waiting 250 ms.  Each time this happens
  , we make a DNS lookup call.
  

Local fix

Problem summary

• ****************************************************************
  USERS AFFECTED:
  Users exploiting SSL and suffering from unexpected client
  termination. It is very difficult to predict under what
  circumstances the code might be unlucky enough to return
  an errno to GSKit which might imply a retry is appropriate.
  
  Platforms affected:
   All Distributed (iSeries, all Unix and Windows)
  ****************************************************************
  PROBLEM SUMMARY:
  The interface between MQ and GSKit involves registering a
  callback function for reading data from TCP. This interface
  specification states that when a negative return code is set
  then an appropriate errno should be set, however MQ is not
  setting the errno appropriately.
  

Problem conclusion

• Set errno to an appropriate value in the MQ SSL read callback
  function.
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
                     v5.3
  Platform           Fix Pack 14
  --------           --------------------
  Windows            U200266
  AIX                U808477
  HP-UX (PA-RISC)    U808478
  Solaris (SPARC)    U808480
  iSeries            SI24366
  Linux (x86)        U808481
  Linux (zSeries)    U808483
  
                     v6.0
  Platform           Fix Pack 6.0.2.2
  --------           --------------------
  Windows            U200270
  AIX                U809895
  HP-UX (PA-RISC)    U809898
  HP-UX (Itanium)    U810084
  Solaris (SPARC)    U809913
  Solaris (x86-64)   U810362
  iSeries            SI27286
  Linux (x86)        U809950
  Linux (x86-64)     U810178
  Linux (zSeries)    U810081
  Linux (Power)      U810083
  Linux (s390x)      U810110
  
  The latest available maintenance can be obtained from
  'WebSphere MQ Recommended Fixes'
  http://www-1.ibm.com/support/docview.wss?rs=171&uid=swg27006037
  
  If the maintenance level is not yet available, information on
  its planned availability can be found in 'WebSphere MQ
  Planned Maintenance Release Dates'
  http://www-1.ibm.com/support/docview.wss?rs=171&uid=swg27006309
  ---------------------------------------------------------------
  

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:

Fix information

• Fixed component name

  WMQ LIN X86 V6

• Fixed component ID

  5724H7204

Applicable component levels

• R600 PSY

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