Adding requested Rewrite Rule to force request header values

jetty-rewrite/src/main/java/org/eclipse/jetty/rewrite/handler/ForceRequestHeaderValueRule.java

@@ -0,0 +1,73 @@
+//
+//  ========================================================================
+//  Copyright (c) 1995-2021 Mort Bay Consulting Pty Ltd and others.
+//  ------------------------------------------------------------------------
+//  All rights reserved. This program and the accompanying materials
+//  are made available under the terms of the Eclipse Public License v1.0
+//  and Apache License v2.0 which accompanies this distribution.
+//
+//      The Eclipse Public License is available at
+//      http://www.eclipse.org/legal/epl-v10.html
+//
+//      The Apache License v2.0 is available at
+//      http://www.opensource.org/licenses/apache2.0.php
+//
+//  You may elect to redistribute this code under either of these licenses.
+//  ========================================================================
+//
+
+package org.eclipse.jetty.rewrite.handler;
+
+import java.io.IOException;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+import org.eclipse.jetty.server.Request;
+
+public class ForceRequestHeaderValueRule extends Rule
+{
+    private String headerName;
+    private String forcedValue;
+
+    public String getHeaderName()
+    {
+        return headerName;
+    }
+
+    public void setHeaderName(String headerName)
+    {
+        this.headerName = headerName;
+    }
+
+    public String getForcedValue()
+    {
+        return forcedValue;
+    }
+
+    public void setForcedValue(String forcedValue)
+    {
+        this.forcedValue = forcedValue;
+    }
+
+    @Override
+    public String matchAndApply(String target, HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse) throws IOException
+    {
+        String existingValue = httpServletRequest.getHeader(headerName);
+        if (existingValue == null)
+        {
+            // no hit, skip this rule.
+            return null;
+        }
+
+        if (existingValue.equals(forcedValue))
+        {
+            // already what we expect, skip this rule.
+            return null;
+        }
+
+        Request baseRequest = Request.getBaseRequest(httpServletRequest);
+        baseRequest.getHttpFields().remove(headerName);
+        baseRequest.getHttpFields().add(headerName, forcedValue);
+        return target;
+    }
+}

jetty-rewrite/src/test/java/org/eclipse/jetty/rewrite/handler/ForceRequestHeaderValueRuleTest.java

@@ -0,0 +1,187 @@
+//
+//  ========================================================================
+//  Copyright (c) 1995-2021 Mort Bay Consulting Pty Ltd and others.
+//  ------------------------------------------------------------------------
+//  All rights reserved. This program and the accompanying materials
+//  are made available under the terms of the Eclipse Public License v1.0
+//  and Apache License v2.0 which accompanies this distribution.
+//
+//      The Eclipse Public License is available at
+//      http://www.eclipse.org/legal/epl-v10.html
+//
+//      The Apache License v2.0 is available at
+//      http://www.opensource.org/licenses/apache2.0.php
+//
+//  You may elect to redistribute this code under either of these licenses.
+//  ========================================================================
+//
+
+package org.eclipse.jetty.rewrite.handler;
+
+import java.io.IOException;
+import java.io.OutputStream;
+import java.io.OutputStreamWriter;
+import java.util.Collections;
+import javax.servlet.ServletException;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+import org.eclipse.jetty.http.HttpTester;
+import org.eclipse.jetty.server.Handler;
+import org.eclipse.jetty.server.LocalConnector;
+import org.eclipse.jetty.server.Request;
+import org.eclipse.jetty.server.Server;
+import org.eclipse.jetty.server.handler.AbstractHandler;
+import org.eclipse.jetty.server.handler.HandlerList;
+import org.eclipse.jetty.util.component.LifeCycle;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.containsString;
+import static org.hamcrest.Matchers.not;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class ForceRequestHeaderValueRuleTest
+{
+    private Server server;
+    private LocalConnector connector;
+    private ForceRequestHeaderValueRule rule;
+
+    @BeforeEach
+    public void setup() throws Exception
+    {
+        server = new Server();
+        connector = new LocalConnector(server);
+        server.addConnector(connector);
+
+        HandlerList handlers = new HandlerList();
+
+        RewriteHandler rewriteHandler = new RewriteHandler();
+        rule = new ForceRequestHeaderValueRule();
+        rewriteHandler.addRule(rule);
+
+        Handler handler = new AbstractHandler()
+        {
+            @Override
+            public void handle(String target, Request baseRequest, HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException
+            {
+                response.setContentType("text/plain");
+                response.setCharacterEncoding("utf-8");
+                OutputStream stream = response.getOutputStream();
+                OutputStreamWriter out = new OutputStreamWriter(stream);
+                out.append("Echo\n");
+                for (String headerName : Collections.list(request.getHeaderNames()))
+                {
+                    // Combine all values for header into single output on response body
+                    out.append("Request Header[").append(headerName).append("]: [")
+                        .append(request.getHeader(headerName)).append("]\n");
+                }
+                out.flush();
+                baseRequest.setHandled(true);
+            }
+        };
+
+        handlers.addHandler(rewriteHandler);
+        handlers.addHandler(handler);
+        server.setHandler(handlers);
+        server.start();
+    }
+
+    @AfterEach
+    public void teardown()
+    {
+        LifeCycle.stop(server);
+    }
+
+    @Test
+    public void testNormalRequest() throws Exception
+    {
+        rule.setHeaderName("Accept");
+        rule.setForcedValue("*/*");
+
+        StringBuilder request = new StringBuilder();
+        request.append("GET /echo/foo HTTP/1.1\r\n");
+        request.append("Host: local\r\n");
+        request.append("Connection: closed\r\n");
+        request.append("\r\n");
+
+        HttpTester.Response response = HttpTester.parseResponse(connector.getResponse(request.toString()));
+        assertEquals(200, response.getStatus());
+        assertThat(response.getContent(), not(containsString("[Accept]")));
+        assertThat(response.getContent(), containsString("[Host]: [local]"));
+        assertThat(response.getContent(), containsString("[Connection]: [closed]"));
+    }
+
+    @Test
+    public void testOneAcceptHeaderRequest() throws Exception
+    {
+        rule.setHeaderName("Accept");
+        rule.setForcedValue("*/*");
+
+        StringBuilder request = new StringBuilder();
+        request.append("GET /echo/foo HTTP/1.1\r\n");
+        request.append("Host: local\r\n");
+        request.append("Accept: */*\r\n");
+        request.append("Connection: closed\r\n");
+        request.append("\r\n");
+
+        String rawResponse = connector.getResponse(request.toString());
+        HttpTester.Response response = HttpTester.parseResponse(rawResponse);
+        assertEquals(200, response.getStatus());
+        assertThat(response.getContent(), containsString("[Accept]: [*/*]"));
+        assertThat(response.getContent(), containsString("[Host]: [local]"));
+        assertThat(response.getContent(), containsString("[Connection]: [closed]"));
+    }
+
+    @Test
+    public void testThreeAcceptHeadersRequest() throws Exception
+    {
+        rule.setHeaderName("Accept");
+        rule.setForcedValue("*/*");
+
+        StringBuilder request = new StringBuilder();
+        request.append("GET /echo/foo HTTP/1.1\r\n");
+        request.append("Host: local\r\n");
+        request.append("Accept: images/jpeg\r\n");
+        request.append("Accept: text/plain\r\n");
+        request.append("Accept: */*\r\n");
+        request.append("Connection: closed\r\n");
+        request.append("\r\n");
+
+        String rawResponse = connector.getResponse(request.toString());
+        HttpTester.Response response = HttpTester.parseResponse(rawResponse);
+        assertEquals(200, response.getStatus());
+        assertThat(response.getContent(), containsString("[Accept]: [*/*]"));
+        assertThat(response.getContent(), containsString("[Host]: [local]"));
+        assertThat(response.getContent(), containsString("[Connection]: [closed]"));
+    }
+
+    @Test
+    public void testInterleavedAcceptHeadersRequest() throws Exception
+    {
+        rule.setHeaderName("Accept");
+        rule.setForcedValue("*/*");
+
+        StringBuilder request = new StringBuilder();
+        request.append("GET /echo/foo HTTP/1.1\r\n");
+        request.append("Host: local\r\n");
+        request.append("Accept: images/jpeg\r\n"); // not value intended to be forced
+        request.append("Accept-Encoding: gzip;q=1.0, identity; q=0.5, *;q=0\r\n");
+        request.append("accept: text/plain\r\n"); // interleaved with other headers shouldn't matter
+        request.append("Accept-Charset: iso-8859-5, unicode-1-1;q=0.8\r\n");
+        request.append("ACCEPT: */*\r\n"); // case shouldn't matter
+        request.append("Connection: closed\r\n");
+        request.append("\r\n");
+
+        String rawResponse = connector.getResponse(request.toString());
+        HttpTester.Response response = HttpTester.parseResponse(rawResponse);
+        assertEquals(200, response.getStatus());
+        assertThat(response.getContent(), containsString("[Accept]: [*/*]"));
+        assertThat(response.getContent(), containsString("[Accept-Charset]: [iso-8859-5, unicode-1-1;q=0.8]"));
+        assertThat(response.getContent(), containsString("[Accept-Encoding]: [gzip;q=1.0, identity; q=0.5, *;q=0]"));
+        assertThat(response.getContent(), containsString("[Host]: [local]"));
+        assertThat(response.getContent(), containsString("[Connection]: [closed]"));
+    }
+}