Question

How can I make a java-based application server reply with an empty-valued response header, like this?

content-length:\r\n

Unfortunately when I call

response.setHeader("Content-Length", len)

where len is either an empty string or null, the response will not include the header.

I’ve checked the HttpServletResponse and HttpServletResponseWrapper javadocs but couldn’t figure out what could be overriden to provide my custom behaviour.

Background

I’m building a testing application that is supposed to emulate badly-behaved HTTP server scenarios. The application is supposed to reply to requests with preset pages and HTTP headers, including malformed ones like the above case.
The application is written in grails.

Answer 1

I’m building a testing application that is supposed to emulate badly-behaved HTTP server scenarios.

In such a case, attempting to get a well-behaving server to mimic such behavior is a bad idea. If you need to mimic a bad server, or a particular set of scenarios you wish to test, then you may do one of the following:

• write a custom application that listens on a particular port (using the ServerSocket class) that will respond with malformed HTTP headers. Using HTTP libraries may not help, for libraries may have code to detect erroneous conditions and correct them automatically.
• use a HTTP proxy that is capable of intercepting responses and allows for modifications of these responses. You will find several if you Google for “http debugging proxy”, but if you haven’t heard of any, I would suggest looking at Fiddler, WebScarab or Burp.