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IT25277: MQXR: Unexpected DISCONNECT packet from MQTT client causes FDC XR070013 PROTOCOL_HEADER error

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APAR status

  • Closed as program error.

Error description

  • MQXR Service received an unexpected DISCONNECT packet from an
    MQTT client which caused the following FDC:
    
    
    | Source Class      :- com.ibm.mq.MQXRService.MQTTServerSession
                                       |
    | Source Method     :- makeStateChange
                                                                |
    | Probe Id          :- XR070013
    
    java.lang.Exception: State error state:=PROTOCOL_ERROR
    previousState:DISCONNECTED
    	at
    com.ibm.mq.MQXRService.MQTTServerSession.makeStateChange(MQTTSer
    verSession.java:1571)
    	at
    com.ibm.mq.MQXRService.MQTTServerSessionV311.receivePubComp(MQTT
    ServerSessionV311.java:1110)
    	at
    com.ibm.mq.MQXRService.MQTTServerSessionV311.handleReceive(MQTTS
    erverSessionV311.java:145)
    	at
    com.ibm.mq.MQXRService.MQTTServerContext.handleReceive(MQTTServe
    rContext.java:153)
    	at
    com.ibm.mq.MQXRService.MQTTWireContext.receive(MQTTWireContext.j
    ava:403)
    	at
    com.ibm.mq.communications.NonBlockingSslConnection.receive(NonBl
    ockingSslConnection.java:491)
    	at
    com.ibm.mq.communications.NonBlockingWorker.run(NonBlockingWorke
    r.java:398)
    	at java.lang.Thread.run(Thread.java:785)
    
    :---------------------------------------------------------------
    -----------------------------------:
    : Object            :- java.lang.Exception: State error
    state:=PROTOCOL_ERROR previousState:DISCON :
    :                   :- NECTED
    
        :
    
    state=PROTOCOL_ERROR(com.ibm.mq.MQXRService.MQTTServerSession$Co
    ntextState)
    
        Class: class
    com.ibm.mq.MQXRService.MQTTServerSession$ContextState
    previousState=DISCONNECTED(com.ibm.mq.MQXRService.MQTTServerSess
    ion$ContextState)
    history([Lcom.ibm.mq.MQXRService.MQTTServerSession$HistoryEvent;
    )
      0 Wed Apr 05 22:26:07 BST 2017 SEND_MQTT
    mqttMessageType:PUBREL
      1 Wed Apr 05 22:26:07 BST 2017 RECEIVED_MQTT
    mqttMessageType:DISCONNECT
      2 Wed Apr 05 22:26:07 BST 2017 RECEIVED_MQTT
    mqttMessageType:PUBCOMP
      3 Wed Apr 05 22:26:06 BST 2017 SEND_MQTT
    mqttMessageType:SUBACK
      4 Wed Apr 05 22:26:06 BST 2017 RECEIVED_MQTT
    mqttMessageType:PUBLISH
      5 Wed Apr 05 22:26:07 BST 2017 SEND_MQTT
    mqttMessageType:PUBREC
      6 Wed Apr 05 22:26:07 BST 2017 SEND_MQTT
    mqttMessageType:PUBLISH
      7 Wed Apr 05 22:26:07 BST 2017 RECEIVED_MQTT
    mqttMessageType:PUBREL
      8 Wed Apr 05 22:26:07 BST 2017 SEND_MQTT
    mqttMessageType:PUBCOMP
      9 Wed Apr 05 22:26:07 BST 2017 RECEIVED_MQTT
    mqttMessageType:PUBREC
    
      historyIndex=3(int)
    
    SPSS: XRASECB
    

Local fix

  • N/A
    

Problem summary

  • ****************************************************************
    USERS AFFECTED:
    This issue affects users connecting to a queue manager's MQXR
    service with Paho MQTT clients, which disconnect while receiving
    QoS 2 messages from the MQXR server as a result of a previously
    made subscriptions.
    
    
    Platforms affected:
    MultiPlatform
    
    ****************************************************************
    PROBLEM DESCRIPTION:
    The queue manager's MQXR service threw an FDC with probe ID
    XR070013, reporting a PROTOCOL_ERROR. The packet history in the
    FDC showed that a connected MQTT client sent a DISCONNECT packet
    followed by a PUBCOMP packet - for instance:
    
     RECEIVED_MQTT mqttMessageType:DISCONNECT
     RECEIVED_MQTT mqttMessageType:PUBCOMP
    

Problem conclusion

  • When a MQTT client sends a DISCONNECT packet followed by a
    PUBCOMP packet (or other similar invalid combination of MQTT
    packets), an FDC is no longer thrown - instead a message is
    written to the mqxr.log file indicating that a protocol error
    has occurred as a result of MQTT packets being sent in the wrong
    order, giving some details to help identify the client which
    sent the invalid MQTT packets.
    
    For instance for a client which connected using a client
    identifier "client123" from a local IPv6 connection a message
    would be logged like:
    
    AMQXR2087I: Client with identifier 'client123' at network
    address '0:0:0:0:0:0:0:1' sent an unexpected MQTT packet causing
    a protocol error: state: 'PROTOCOL_ERROR' previousState:
    'DISCONNECTED'
    
    ---------------------------------------------------------------
    The fix is targeted for delivery in the following PTFs:
    
    Version    Maintenance Level
    v8.0       8.0.0.11
    v9.0 LTS   9.0.0.6
    v9.1 CD    9.1.2
    v9.1 LTS   9.1.0.2
    
    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 number

    IT25277

  • Reported component name

    IBM MQ BASE M/P

  • Reported component ID

    5724H7261

  • Reported release

    900

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2018-06-06

  • Closed date

    2018-11-15

  • Last modified date

    2018-12-06

  • 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

    IBM MQ BASE M/P

  • Fixed component ID

    5724H7261

Applicable component levels

[{"Business Unit":{"code":"BU053","label":"Cloud & Data Platform"},"Product":{"code":"SSYHRD","label":"IBM MQ"},"Component":"","ARM Category":[],"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"9.0","Edition":"","Line of Business":{"code":"LOB36","label":"IBM Automation"}}]

Document Information

Modified date:
06 December 2018