HttpRequestFilter is currently applied after we've determined the downstream server based on the host header. It would be neat to have the option of applying request filters on the way in, such that the host header can be modified. This test shows an example of how one might use that, provided by Marco Palladino.

AmazonRedirector.java

package org.littleshoot.proxy;

import io.netty.handler.codec.http.HttpRequest;
import io.netty.handler.codec.http.HttpResponse;

/**
 * <p>
 * This is based on some code from Marco Palladino that was giving him trouble.
 * Use the below command to test:
 * </p>
 * 
 * <pre>
 * curl -i http://127.0.0.1:9000
 * </pre>
 * 
 * <p>
 * It doesn't work because by the time the filter is applied, we've already
 * identified and connected to the host (in this case our proxy itself). This
 * results in the request going through the proxy twice.
 * </p>
 */
public class AmazonRedirector {
    public static void main(String[] args) throws Exception {
        final HttpProxyServer server = new DefaultHttpProxyServer(9000,

                new HttpRequestFilter() {

                    @Override
                    public void filter(HttpRequest httpRequest) {
                        System.out.println("Filtering");
                        httpRequest.headers().set("host", "www.amazon.com");
                    }

                }, new HttpResponseFilters() {

                    @Override
                    public HttpFilter getFilter(String hostAndPort) {
                        return new DefaultHttpFilter(new HttpResponseFilter() {

                            @Override
                            public HttpResponse filterResponse(
                                    HttpRequest arg0, HttpResponse arg1) {
                                arg1.headers().add("x-test", "yes");
                                return arg1;
                            }

                        }, new HttpRequestMatcher() {

                            @Override
                            public boolean filterResponses(HttpRequest arg0) {
                                return true;
                            }

                        });
                    }

                });

        server.start();
    }
}