PK85775: MSGDFHWB0001 AN ABEND (CODE 0C4/AKEA) HAS OCCURRED AT OFFSET X'25C4' IN MODULE DFHWBAP WHEN ISSUING WEB EXTRACT

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• You notice your CICS region intermittently receives:
  DFHWB0001 An abend (code 0C4/AKEA) has occurred at offset
  x'25C4' in module DFHWBAP.  The failure occurs on a MVCL
  instruction 0E0E at x'25C2' within DFHWBAP.
  The failing command is a WEB EXTRACT HTTPMETHOD HTTPVERSION
  QUERYSTRING.  The abend0c4 is exposed by the unusual HTTP
  request.  The URI is fully qualified yet the path is empty.
  
  Later on when the EXEC CICS WEB EXTRACT HTTPVERSION QUERYSTRING
  command executes, we end up in Webrequest_inquire.
  The code processes the HTTPVERSION option OK and at this point
  reg1 happens to be 0.  We now try to process the QUERYSTRING
  option.  scan_ptr points into the HTTP request at the offset
  designated by wrb_resource_offset (past the querystring).
  scan_limit happens to have been set to the same as scan_ptr.
  The consequence is that we fail to execute the code which
  searches for the '?' which starts the querystring.
  
  The code now checks reg2 assuming that we performed some kind
  of search.  Register 2 is non-zero and happens to point to a
  work buffer.  The code assumes that the querystring has been
  located and that reg1 points there.  Register 1 actually points
  to low core.  The code now tries to copy from low core into the
  caller's buffer using a source length which is enormous.
  During this copy from lowcore, we encounter a page which is
  fetch protected causing the program check.
  Additional Symptom(s) Search Keyword(s):
  kIXREVSCB
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All CICS users.                              *
  ****************************************************************
  * PROBLEM DESCRIPTION: DFHWB0001 AN ABEND (CODE 0C4/AKEA) HAS  *
  *                      OCCURRED AT OFFSET X'25C4' IN MODULE    *
  *                      DFHWBAP when issuing EXEC CICS WEB      *
  *                      EXTRACT.                                *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  A client sends in an HTTP request to CICS.  The first line of
  this request is of the form;
  
    GET http://hostname:port?field1=value1 HTTP/1.1
  
  The resource component is an absolute URI that contains a
  querystring but does not contain a path.
  
  When the request is received DFHWBSR parses the first line and
  works out offsets and lengths of the various components.  When
  processing the absolute URI the hostname and port need to be
  skipped over as they only identify the target server and not
  the respurce on that server.  The code that skips over the
  hostname and port is expecting to find a '/' character which
  would indicate the start of the path.  The '/' is not present
  so scanning continues until the next space is located.  This
  position is assumed to be the start of the resource.
  
  wrb_resource_offset and wrb_resource_length now get set
  incorrectly. The fields wrb_http_version_offset and
  wrb_http_version_length are also incorrect as the parsing code
  failed to correctly locate the HTTP version.
  
  When a later EXEC CICS WEB EXTRACT HTTPVERSION() QUERYSTRING()
  command is issued, DFHWBAP uses wrb_resource_offset to begin
  the search for the querystring.  Due to wrb_resource_offset
  being wrong the start and end points of the search end up the
  same so the TRT to locate the '?' is never executed.  As a
  result, registers 1 and 2 contain residual values.  The query
  string is then copied to the callers buffer starting at the
  location addressed by register 1.  This copying causes an
  ABEND0C4 when it attempts to read from inaccessible storage.
  
  Additional keywords:
  S0C4  ABENDS0C4  WB0001  CWXN  MSGDFHWB0001
  

Problem conclusion

• DFHWBSR has been changed to correctly parse the first line of
  an HTTP request that contains an absolute URI with a
  querystring and without a path.
  

Temporary fix

• FIX AVAILABLE BY PTF ONLY
  

Comments

APAR Information

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

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

  PK94717 UK50636

Modules/Macros

•    DESWBAP  DESWBDM  DESWBRQ  DESWBRQF DESWBSR
  DESWBXM  DFHWBAP  DFHWBAPF DFHWBDM  DFHWBRQS DFHWBSR  DFHWBXM
  

Fix information

• Fixed component name

  CICSTS V3 Z/OS

• Fixed component ID

  5655M1500

Applicable component levels

• R500 PSY UK50636

     UP09/10/05 P F910

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.