Wrong value of javax.servlet.forward.context_path attribute

[grgrzybek]

Jetty version(s)
10.0.13

Java version/vendor (use: java -version)
11.0.7

OS type/version
Linux/Fedora 37

Description
I work on Pax Web project and it unifies 3 embedded web servers (Jetty, Tomcat and Undertow) in OSGi runtime.
I try hard to make the tests consistent and ensure similar behavior between the runtimes.

According to Chapter 9.4.2 Forwarded Request Parameters of the Servlets 4 specification:

The following request attributes must be set:
javax.servlet.forward.mapping
javax.servlet.forward.request_uri
javax.servlet.forward.context_path
javax.servlet.forward.servlet_path
javax.servlet.forward.path_info
javax.servlet.forward.query_string
The values of these attributes must be equal to the return values of the
HttpServletRequest methods getRequestURI, getContextPath, getServletPath,
getPathInfo, getQueryString respectively, invoked on the request object passed to
the first servlet object in the call chain that received the request from the client.

When using Jetty 9.4.50, I see correct (in org.eclipse.jetty.server.Dispatcher#forward()):

final String old_context_path = baseRequest.getContextPath();
...
ForwardAttributes attr = new ForwardAttributes(old_attr);
...
attr._contextPath = old_context_path;

However in Jetty 10, it's:

if (old_attr.getAttribute(FORWARD_REQUEST_URI) == null)
    baseRequest.setAttributes(new ForwardAttributes(old_attr,
        old_uri.getPath(),
        old_context == null ? null : old_context.getContextHandler().getContextPathEncoded(),
        baseRequest.getPathInContext(),
        source_mapping,
        old_uri.getQuery()));

And the forwarded context path is "/" instead of "" (empty string).

How to reproduce?

I have a "/gateway/*" mapped servlet with:

protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
	String what = req.getParameter("what");
	String where = req.getParameter("where");
	switch (what) {
		case "redirect":
			resp.sendRedirect(where);
			return;
		case "forward":
			// we can't send anything when forwarding
			req.getRequestDispatcher(where).forward(req, resp);
			return;
		case "include":
			resp.getWriter().print(">>>");
			req.getRequestDispatcher(where).include(req, resp);
			resp.getWriter().print("<<<");
			return;
		default:
	}
}

And I call it with this URI:

"/gateway/x?what=forward&where=/"

The test is https://github.com/ops4j/org.ops4j.pax.web/blob/web-9.0.4/pax-web-jetty/src/test/java/org/ops4j/pax/web/service/jetty/internal/UnifiedJettyTest.java#L505-L516

[grgrzybek]

The include attributes are fine - there, org.eclipse.jetty.server.handler.ContextHandler#getRequestContextPath() is used, while in forward, the method is org.eclipse.jetty.server.handler.ContextHandler#getContextPathEncoded().

[joakime]

I have a test case that confirms report.
Working on a fix and PR.

[joakime]

Opened PR #9123 to address this