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  • 1.  'Failed to process response headers' error occuring while connecting with Backend server

    Posted Wed March 29, 2023 07:45 AM

    Hello All,

    We are integrating with a server which is based on .NET framework which respond in below content type:

    type="application/xop+xml";start="http://tempuri.org/0";boundary="uuid:b56f5373-95af-4dc6-bee5-d61241962ba1+id=7";start-info="text/xml"

    Datapower is receiving below while connecting with this server:

    Backside header ('N/A') failed to parse due to: Failed to process response headers

    Application is responding when we directly hitting the backend. So can some one please confirm how we can process this response in datapower. Let me know if further any details required.



    ------------------------------
    Abhishek Rokana
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  • 2.  RE: 'Failed to process response headers' error occuring while connecting with Backend server

    Posted Wed March 29, 2023 04:16 PM

    Abhishek,

    Are you certain the response is coming back to DataPower?  From the error, it appears the back end may just be hanging up.



    ------------------------------
    Joseph Morgan
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    Original Message


  • 3.  RE: 'Failed to process response headers' error occuring while connecting with Backend server

    Posted Thu March 30, 2023 09:03 AM

    Hi Abhishek,
    I agree with Joseph.  I'd suggest you start a packet capture with a filter that specifies host <ip of your  backend server>.  If your connection is https, then request the ssl session keys as part of the capture.  You can use wireshark (use the ssl session keys if needed to decrypt encrypted traffic) to see the packets flowing to and from your backend server to see if anything came back from your backend server, of if a partial response was received.  For  example, I've seen somethings similar in my DataPower consulting days where the response had an incorrect content length header, and DataPower eventually threw this type of error when it timed out waiting for data that would never be sent.  The packet capture will tell you what is going on.

    Best Regards,
    Steve



    ------------------------------
    Steve Linn
    Senior Consulting I/T Specialist
    IBM
    ------------------------------

    Original Message


  • 4.  RE: 'Failed to process response headers' error occuring while connecting with Backend server

    Posted Mon November 06, 2023 08:48 AM
    Edited by Anusha Pudari Mon November 06, 2023 08:48 AM

    Hi Steve Linn,

    We are also  facing same issue while calling external application from Data Power. Uploaded PCAP kindly check.

    Source IP:192.168.104.10(Data Power)

    Destination IP:testbed.ckycindia.in (Call throw Proxy IP:172.16.90.80)



    ------------------------------
    Anusha Pudari
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    Original Message


  • 5.  RE: 'Failed to process response headers' error occuring while connecting with Backend server

    Posted Mon November 06, 2023 08:51 AM
      |   view attached

    Please find the attached file.



    ------------------------------
    Anusha Pudari
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    Attachment(s)

    zip
    capture (1).zip   297 KB 1 version
    Original Message


  • 6.  RE: 'Failed to process response headers' error occuring while connecting with Backend server

    Posted Mon November 06, 2023 09:15 AM

    I'm seeing two different servers behaving the same way.  One is the proxy.  I suppose the other is the internal app.

    In some cases, I see the remote sending a FIN,ACK followed by a DataPower reset.  In a couple this is followed by a renegotiation. 

    Is it making a reconnect to the server every time (I suspect this is possible (maybe even likely) through a proxy).  Is the external (the one of the other side of the proxy) the same .NET app (functionally) as the one internal?



    ------------------------------
    Joseph Morgan
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    Original Message


  • 7.  RE: 'Failed to process response headers' error occuring while connecting with Backend server

    Posted Thu November 09, 2023 04:02 PM

    Hi Anusha,
    Just a brief look at the pcap, your backend (.80) is sending the [FIN,ACK] and then the [RST] to close the connection.  It does acknowledge the application data that was sent (the ACK with the FIN) from the DataPower appliance (.10), but there is something that it obviously doesn't like about the request being sent.  I'd suggest you open a PMR/Support ticket for your issue.  L2 Support has network specialists that could assist.  I'd also suggest on your packet capture you enable the tls session key export (Log TLS Keys in the UI) so the packet capture can be decrypted and you can see what exactly is being sent to your  backend server.  That may tell you why the server doesn't like what it is being provided.  The session key file will be written to the logtemp directory of the default domain.  I'm sure that L2/Support would want to have both the pcap and session key file for review as well if you take that route.

    Best Regards,

    Steve



    ------------------------------
    Steve Linn
    Senior Consulting I/T Specialist
    IBM
    ------------------------------

    Original Message


  • 8.  RE: 'Failed to process response headers' error occuring while connecting with Backend server

    Posted Fri November 10, 2023 05:15 AM
    Edited by Hermann Stamm-Wilbrandt Fri November 10, 2023 05:15 AM

    Hi,

    please do a packet capture and decrypt as Steve told. Here are the details on how to do that:
    https://github.com/ibm-datapower/datapower-tutorials/blob/master/decrypt-tls-using-master-secret-logging/decrypt-tls-using-master-secret-logging.md

    But in case what DP sends against backend is what you expect, please open a support ticket with your backend product.
    DP is normally not responsible for a backend closing the connection.



    ------------------------------
    Hermann Stamm-Wilbrandt
    Compiler Level 3 support, IBM DataPower Gateways
    IBM
    Boeblingen Germany
    ------------------------------

    Original Message