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PM44423: INVALID HTTP RESPONSE CAUSES LOOP IN DFHWBCL

A fix is available

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APAR status

  • Closed as program error.

Error description

  • Invalid HTTP response causes loop in DFHWBCL
    Application program is doing an E.C.WEB CONVERSE.
    A loop is caused by an invalid HTTP response received
    from the remote server.
    The HTTP headers are terminated by only a CR instead of
    a CRLF, and the headers end with a double CR instead
    of a double CRLF.
    .
    This invalid response has caused DFHWBCL to fail
    to find the end of the HTTP headers in the first 4K
    of data received.  The code then ends up trying to receive
    more data into an already full 4K buffer and ends up
    looping making zero length receives.
    .
    If a valid HTTP response was received from the server
    then the loop would not occur.
    

Local fix

  • *
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED: All CICS users.                              *
    ****************************************************************
    * PROBLEM DESCRIPTION: DFHWBCL enters a non-yielding infinite  *
    *                      loop which can only be broken by        *
    *                      recycling the CICS region.              *
    ****************************************************************
    * RECOMMENDATION:                                              *
    ****************************************************************
    If CICS receives more than 4K of HTTP header information,
    DFHWBCL will enter an infinite loop. The prescan_headers
    routine assumes that it will always find the CRLFCRLF sequence
    within 4K. If this does not occur, the loop is entered and
    will never yield. Only a CICS restart will break the loop.
    

Problem conclusion

  • DFHWBCL has been changed in routine prescan_headers so that if
    there is no more space in the buffer being used to peek the
    incoming data, the loop is exited with an exception response.
    

Temporary fix

  • FIX AVAILABLE BY PTF ONLY
    

Comments

APAR Information

  • APAR number

    PM44423

  • Reported component name

    CICS TS Z/OS V4

  • Reported component ID

    5655S9700

  • Reported release

    600

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2011-07-27

  • Closed date

    2011-09-15

  • Last modified date

    2011-11-02

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

    PM44057

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

    UK72084 UK72085

Modules/Macros

  •    DESWBCL  DFHWBCL
    

Fix information

  • Fixed component name

    CICS TS Z/OS V4

  • Fixed component ID

    5655S9700

Applicable component levels

  • R600 PSY UK72084

       UP11/10/05 P F110

  • R700 PSY UK72085

       UP11/10/05 P F110

Fix is available

  • Select the PTF appropriate for your component level. You will be required to sign in. Distribution on physical media is not available in all countries.

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Document Information

Modified date:
02 November 2011