Why is the POST body unavailable to my servlet when the RequestDumperValve is enabled?

Solution Unverified - Updated

Environment

  • JBoss Enterprise Applicatoin Platform (EAP) 4.x

  • JBoss Enterprise Applicatoin Platform (EAP) 5.x

Issue

  • A client executes an HTTP POST containing a payload that a servlet parses.  When the RequestDumperValve is enabled, the payload is no longer available to the servlet.

Resolution

  • Explicitly set the ContentType on the client to something other than application/x-ww-form-urlencoded; e.g., application/soap+xml

Root Cause

  • The client either is not specifying a ContentType header or is specifying a ContentType of application/x-www-form-urlencoded.
  • When the RequestDumperValve is enabled, it repeatedly calls ServletRequest#getParameter(java.lang.String) for each parameter, which causes the ServletInputStream to be read and parsed into parameters if the ContentType is application/x-www-form-urlencoded.
  • Thus, when the servlet recieves the request, the POST body is no longer available.

Diagnostic Steps

  • Execute the client without and then with the RequestDumperValve enabled.
  • If POST is still unavailable when removing the RequestDumperValve use Byteman to determine what is calling the getInputStream prematurely, most likely another filter: Using Byteman to troubleshoot Java issues

Notes

The javadoc for ServletRequest#getParameter [0] warns about processing of the input stream because of the parsing it will do on  its own.

The w3c states [1] that application/x-www-form-urlencoded is the default content-type for form submissions.

[0]  Content from docs.oracle.com is not included.Content from docs.oracle.com is not included.http://docs.oracle.com/javaee/6/api/javax/servlet/ServletRequest.html#getParameter%28java.lang.String%29

[1]  Content from www.w3.org is not included.Content from www.w3.org is not included.http://www.w3.org/TR/html4/interact/forms.html#h-17.13.4

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