com.qlkh.client.server.proxy.ProxyServlet.java Source code

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/*
 * Copyright (C) 2012 - 2013 Nguyen Duc Dung (dungvn3000@gmail.com)
 */

/*
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.qlkh.client.server.proxy;

import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
import org.apache.commons.httpclient.Header;
import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.HttpMethod;
import org.apache.commons.httpclient.NameValuePair;
import org.apache.commons.httpclient.methods.GetMethod;
import org.apache.commons.httpclient.methods.PostMethod;
import org.apache.commons.httpclient.methods.StringRequestEntity;
import org.apache.commons.httpclient.methods.multipart.*;
import org.apache.commons.httpclient.protocol.Protocol;

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.*;
import java.util.*;
import java.util.zip.GZIPInputStream;

/**
 * ProxyServlet from http://edwardstx.net/wiki/attach/HttpProxyServlet/ProxyServlet.java
 * (This seems to be a derivative of Noodle -- http://noodle.tigris.org/)
 * <p/>
 * Patched to skip "Transfer-Encoding: chunked" headers, avoid double slashes
 * in proxied URLs, handle GZip and allow GWT RPC.
 * <p/>
 * - [florin] - added support for utf-8 character encoding, gzip and for obtaining
 * a better performance. Added log4j support
 * <p/>
 * =================================================================
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation. For more
 * information on the Apache Software Foundation, please see
 */
public class ProxyServlet extends HttpServlet {

    private static final int FOUR_KB = 4196;

    /**
     * Serialization UID.
     */
    private static final long serialVersionUID = 1L;
    /**
     * Key for redirect location header.
     */
    private static final String STRING_LOCATION_HEADER = "Location";
    /**
     * Key for content type header.
     */
    private static final String STRING_CONTENT_TYPE_HEADER_NAME = "Content-Type";
    /**
     * Key for content length header.
     */
    private static final String STRING_CONTENT_LENGTH_HEADER_NAME = "Content-Length";
    /**
     * Key for host header
     */
    private static final String STRING_HOST_HEADER_NAME = "Host";
    /**
     * The directory to use to temporarily store uploaded files
     */
    private static final File FILE_UPLOAD_TEMP_DIRECTORY = new File(System.getProperty("java.io.tmpdir"));

    // Proxy host params
    /**
     * The host to which we are proxying requests. Default value is "localhost".
     */
    private String stringProxyHost = "localhost";
    /**
     * The port on the proxy host to wihch we are proxying requests. Default value is 80.
     */
    private int intProxyPort = 80;
    /**
     * The (optional) path on the proxy host to wihch we are proxying requests. Default value is "".
     */
    private String stringProxyPath = "";
    /**
     * Setting that allows removing the initial path from client. Allows specifying /twitter/* as synonym for twitter.com.
     */
    private boolean removePrefix;
    /**
     * The maximum size for uploaded files in bytes. Default value is 5MB.
     */
    private int intMaxFileUploadSize = 5 * 1024 * 1024;
    private boolean followRedirects;

    /**
     * Initialize the <code>ProxyServlet</code>
     *
     * @param servletConfig The Servlet configuration passed in by the servlet container
     */
    public void init(ServletConfig servletConfig) {
        // Get the proxy host
        String stringProxyHostNew = servletConfig.getInitParameter("proxyHost");
        if (stringProxyHostNew == null || stringProxyHostNew.length() == 0) {
            throw new IllegalArgumentException("Proxy host not set, please set init-param 'proxyHost' in web.xml");
        }
        this.setProxyHost(stringProxyHostNew);
        // Get the proxy port if specified
        String stringProxyPortNew = servletConfig.getInitParameter("proxyPort");
        if (stringProxyPortNew != null && stringProxyPortNew.length() > 0) {
            this.setProxyPort(Integer.parseInt(stringProxyPortNew));
        }
        // Get the proxy path if specified
        String stringProxyPathNew = servletConfig.getInitParameter("proxyPath");
        if (stringProxyPathNew != null && stringProxyPathNew.length() > 0) {
            this.setProxyPath(stringProxyPathNew);
        }
        // Get the maximum file upload size if specified
        String stringMaxFileUploadSize = servletConfig.getInitParameter("maxFileUploadSize");
        if (stringMaxFileUploadSize != null && stringMaxFileUploadSize.length() > 0) {
            this.setMaxFileUploadSize(Integer.parseInt(stringMaxFileUploadSize));
        }

    }

    /**
     * Performs an HTTP GET request
     *
     * @param httpServletRequest  The {@link javax.servlet.http.HttpServletRequest} object passed
     *                            in by the servlet engine representing the
     *                            client request to be proxied
     * @param httpServletResponse The {@link javax.servlet.http.HttpServletResponse} object by which
     *                            we can send a proxied response to the client
     */
    public void doGet(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse)
            throws IOException, ServletException {
        // Create a GET request
        String destinationUrl = this.getProxyURL(httpServletRequest);
        debug("GET Request URL: " + httpServletRequest.getRequestURL(), "Destination URL: " + destinationUrl);
        GetMethod getMethodProxyRequest = new GetMethod(destinationUrl);
        // Forward the request headers
        setProxyRequestHeaders(httpServletRequest, getMethodProxyRequest);
        setProxyRequestCookies(httpServletRequest, getMethodProxyRequest);
        // Execute the proxy request
        this.executeProxyRequest(getMethodProxyRequest, httpServletRequest, httpServletResponse);
    }

    /**
     * Performs an HTTP POST request
     *
     * @param httpServletRequest  The {@link javax.servlet.http.HttpServletRequest} object passed
     *                            in by the servlet engine representing the
     *                            client request to be proxied
     * @param httpServletResponse The {@link javax.servlet.http.HttpServletResponse} object by which
     *                            we can send a proxied response to the client
     */
    public void doPost(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse)
            throws IOException, ServletException {
        // Create a standard POST request
        String contentType = httpServletRequest.getContentType();
        String destinationUrl = this.getProxyURL(httpServletRequest);
        debug("POST Request URL: " + httpServletRequest.getRequestURL(), "    Content Type: " + contentType,
                " Destination URL: " + destinationUrl);
        PostMethod postMethodProxyRequest = new PostMethod(destinationUrl);
        // Forward the request headers
        setProxyRequestHeaders(httpServletRequest, postMethodProxyRequest);
        setProxyRequestCookies(httpServletRequest, postMethodProxyRequest);
        // Check if this is a mulitpart (file upload) POST
        if (ServletFileUpload.isMultipartContent(httpServletRequest)) {
            this.handleMultipartPost(postMethodProxyRequest, httpServletRequest);
        } else {
            if (contentType == null || PostMethod.FORM_URL_ENCODED_CONTENT_TYPE.equals(contentType)) {
                this.handleStandardPost(postMethodProxyRequest, httpServletRequest);
            } else {
                this.handleContentPost(postMethodProxyRequest, httpServletRequest);
            }
        }
        // Execute the proxy request
        this.executeProxyRequest(postMethodProxyRequest, httpServletRequest, httpServletResponse);
    }

    /**
     * Sets up the given {@link org.apache.commons.httpclient.methods.PostMethod} to send the same multipart POST
     * data as was sent in the given {@link javax.servlet.http.HttpServletRequest}
     *
     * @param postMethodProxyRequest The {@link org.apache.commons.httpclient.methods.PostMethod} that we are
     *                               configuring to send a multipart POST request
     * @param httpServletRequest     The {@link javax.servlet.http.HttpServletRequest} that contains
     *                               the mutlipart POST data to be sent via the {@link org.apache.commons.httpclient.methods.PostMethod}
     */
    @SuppressWarnings("unchecked")
    private void handleMultipartPost(PostMethod postMethodProxyRequest, HttpServletRequest httpServletRequest)
            throws ServletException {
        // Create a factory for disk-based file items
        DiskFileItemFactory diskFileItemFactory = new DiskFileItemFactory();
        // Set factory constraints
        diskFileItemFactory.setSizeThreshold(this.getMaxFileUploadSize());
        diskFileItemFactory.setRepository(FILE_UPLOAD_TEMP_DIRECTORY);
        // Create a new file upload handler
        ServletFileUpload servletFileUpload = new ServletFileUpload(diskFileItemFactory);
        // Parse the request
        try {
            // Get the multipart items as a list
            List<FileItem> listFileItems = (List<FileItem>) servletFileUpload.parseRequest(httpServletRequest);
            // Create a list to hold all of the parts
            List<Part> listParts = new ArrayList<Part>();
            // Iterate the multipart items list
            for (FileItem fileItemCurrent : listFileItems) {
                // If the current item is a form field, then create a string part
                if (fileItemCurrent.isFormField()) {
                    StringPart stringPart = new StringPart(fileItemCurrent.getFieldName(), // The field name
                            fileItemCurrent.getString() // The field value
                    );
                    // Add the part to the list
                    listParts.add(stringPart);
                } else {
                    // The item is a file upload, so we create a FilePart
                    FilePart filePart = new FilePart(fileItemCurrent.getFieldName(), // The field name
                            new ByteArrayPartSource(fileItemCurrent.getName(), // The uploaded file name
                                    fileItemCurrent.get() // The uploaded file contents
                            ));
                    // Add the part to the list
                    listParts.add(filePart);
                }
            }
            MultipartRequestEntity multipartRequestEntity = new MultipartRequestEntity(
                    listParts.toArray(new Part[] {}), postMethodProxyRequest.getParams());
            postMethodProxyRequest.setRequestEntity(multipartRequestEntity);
            // The current content-type header (received from the client) IS of
            // type "multipart/form-data", but the content-type header also
            // contains the chunk boundary string of the chunks. Currently, this
            // header is using the boundary of the client request, since we
            // blindly copied all headers from the client request to the proxy
            // request. However, we are creating a new request with a new chunk
            // boundary string, so it is necessary that we re-set the
            // content-type string to reflect the new chunk boundary string
            postMethodProxyRequest.setRequestHeader(STRING_CONTENT_TYPE_HEADER_NAME,
                    multipartRequestEntity.getContentType());
        } catch (FileUploadException fileUploadException) {
            throw new ServletException(fileUploadException);
        }
    }

    /**
     * Sets up the given {@link org.apache.commons.httpclient.methods.PostMethod} to send the same standard POST
     * data as was sent in the given {@link javax.servlet.http.HttpServletRequest}
     *
     * @param postMethodProxyRequest The {@link org.apache.commons.httpclient.methods.PostMethod} that we are
     *                               configuring to send a standard POST request
     * @param httpServletRequest     The {@link javax.servlet.http.HttpServletRequest} that contains
     *                               the POST data to be sent via the {@link org.apache.commons.httpclient.methods.PostMethod}
     */
    @SuppressWarnings("unchecked")
    private void handleStandardPost(PostMethod postMethodProxyRequest, HttpServletRequest httpServletRequest) {
        // Get the client POST data as a Map
        Map<String, String[]> mapPostParameters = (Map<String, String[]>) httpServletRequest.getParameterMap();
        // Create a List to hold the NameValuePairs to be passed to the PostMethod
        List<NameValuePair> listNameValuePairs = new ArrayList<NameValuePair>();
        // Iterate the parameter names
        for (String stringParameterName : mapPostParameters.keySet()) {
            // Iterate the values for each parameter name
            String[] stringArrayParameterValues = mapPostParameters.get(stringParameterName);
            for (String stringParamterValue : stringArrayParameterValues) {
                // Create a NameValuePair and store in list
                NameValuePair nameValuePair = new NameValuePair(stringParameterName, stringParamterValue);
                listNameValuePairs.add(nameValuePair);
            }
        }
        // Set the proxy request POST data
        postMethodProxyRequest.setRequestBody(listNameValuePairs.toArray(new NameValuePair[] {}));
    }

    /**
     * Sets up the given {@link org.apache.commons.httpclient.methods.PostMethod} to send the same content POST
     * data (JSON, XML, etc.) as was sent in the given {@link javax.servlet.http.HttpServletRequest}
     *
     * @param postMethodProxyRequest The {@link org.apache.commons.httpclient.methods.PostMethod} that we are
     *                               configuring to send a standard POST request
     * @param httpServletRequest     The {@link javax.servlet.http.HttpServletRequest} that contains
     *                               the POST data to be sent via the {@link org.apache.commons.httpclient.methods.PostMethod}
     */
    private void handleContentPost(PostMethod postMethodProxyRequest, HttpServletRequest httpServletRequest)
            throws IOException, ServletException {
        StringBuilder content = new StringBuilder();
        BufferedReader reader = httpServletRequest.getReader();
        for (;;) {
            String line = reader.readLine();
            if (line == null)
                break;
            content.append(line);
        }

        String contentType = httpServletRequest.getContentType();
        String postContent = content.toString();

        if (contentType.startsWith("text/x-gwt-rpc")) {
            String clientHost = httpServletRequest.getLocalName();
            if (clientHost.equals("127.0.0.1")) {
                clientHost = "localhost";
            }

            int clientPort = httpServletRequest.getLocalPort();
            String clientUrl = clientHost + ((clientPort != 80) ? ":" + clientPort : "");
            String serverUrl = stringProxyHost + ((intProxyPort != 80) ? ":" + intProxyPort : "")
                    + httpServletRequest.getServletPath();
            //debug("Replacing client (" + clientUrl + ") with server (" + serverUrl + ")");
            postContent = postContent.replace(clientUrl, serverUrl);
        }

        String encoding = httpServletRequest.getCharacterEncoding();
        debug("POST Content Type: " + contentType + " Encoding: " + encoding, "Content: " + postContent);
        StringRequestEntity entity;
        try {
            entity = new StringRequestEntity(postContent, contentType, encoding);
        } catch (UnsupportedEncodingException e) {
            throw new ServletException(e);
        }
        // Set the proxy request POST data
        postMethodProxyRequest.setRequestEntity(entity);
    }

    /**
     * Executes the {@link org.apache.commons.httpclient.HttpMethod} passed in and sends the proxy response
     * back to the client via the given {@link javax.servlet.http.HttpServletResponse}
     *
     * @param httpMethodProxyRequest An object representing the proxy request to be made
     * @param httpServletResponse    An object by which we can send the proxied
     *                               response back to the client
     * @throws java.io.IOException      Can be thrown by the {@link org.apache.commons.httpclient.HttpClient}.executeMethod
     * @throws javax.servlet.ServletException Can be thrown to indicate that another error has occurred
     */
    private void executeProxyRequest(HttpMethod httpMethodProxyRequest, HttpServletRequest httpServletRequest,
            HttpServletResponse httpServletResponse) throws IOException, ServletException {

        if (httpServletRequest.isSecure()) {
            Protocol.registerProtocol("https", new Protocol("https", new EasySSLProtocolSocketFactory(), 443));
        }
        // Create a default HttpClient
        HttpClient httpClient = new HttpClient();
        httpMethodProxyRequest.setFollowRedirects(false);
        // Execute the request
        int intProxyResponseCode = httpClient.executeMethod(httpMethodProxyRequest);
        InputStream response = httpMethodProxyRequest.getResponseBodyAsStream();

        // Check if the proxy response is a redirect
        // The following code is adapted from org.tigris.noodle.filters.CheckForRedirect
        // Hooray for open source software
        if (intProxyResponseCode >= HttpServletResponse.SC_MULTIPLE_CHOICES
                /* 300 */ && intProxyResponseCode < HttpServletResponse.SC_NOT_MODIFIED /* 304 */) {
            String stringStatusCode = Integer.toString(intProxyResponseCode);
            String stringLocation = httpMethodProxyRequest.getResponseHeader(STRING_LOCATION_HEADER).getValue();
            if (stringLocation == null) {
                throw new ServletException("Received status code: " + stringStatusCode + " but no "
                        + STRING_LOCATION_HEADER + " header was found in the response");
            }
            // Modify the redirect to go to this proxy servlet rather that the proxied host
            String stringMyHostName = httpServletRequest.getServerName();
            if (httpServletRequest.getServerPort() != 80) {
                stringMyHostName += ":" + httpServletRequest.getServerPort();
            }
            stringMyHostName += httpServletRequest.getContextPath();
            if (followRedirects) {
                if (stringLocation.contains("jsessionid")) {
                    Cookie cookie = new Cookie("JSESSIONID",
                            stringLocation.substring(stringLocation.indexOf("jsessionid=") + 11));
                    cookie.setPath("/");
                    httpServletResponse.addCookie(cookie);
                    //debug("redirecting: set jessionid (" + cookie.getValue() + ") cookie from URL");
                } else if (httpMethodProxyRequest.getResponseHeader("Set-Cookie") != null) {
                    Header header = httpMethodProxyRequest.getResponseHeader("Set-Cookie");
                    String[] cookieDetails = header.getValue().split(";");
                    String[] nameValue = cookieDetails[0].split("=");

                    Cookie cookie = new Cookie(nameValue[0], nameValue[1]);
                    cookie.setPath("/");
                    //debug("redirecting: setting cookie: " + cookie.getName() + ":" + cookie.getValue() + " on " + cookie.getPath());
                    httpServletResponse.addCookie(cookie);
                }
                httpServletResponse.sendRedirect(
                        stringLocation.replace(getProxyHostAndPort() + this.getProxyPath(), stringMyHostName));
                return;
            }
        } else if (intProxyResponseCode == HttpServletResponse.SC_NOT_MODIFIED) {
            // 304 needs special handling.  See:
            // http://www.ics.uci.edu/pub/ietf/http/rfc1945.html#Code304
            // We get a 304 whenever passed an 'If-Modified-Since'
            // header and the data on disk has not changed; server
            // responds w/ a 304 saying I'm not going to send the
            // body because the file has not changed.
            httpServletResponse.setIntHeader(STRING_CONTENT_LENGTH_HEADER_NAME, 0);
            httpServletResponse.setStatus(HttpServletResponse.SC_NOT_MODIFIED);
            return;
        }

        // Pass the response code back to the client
        httpServletResponse.setStatus(intProxyResponseCode);

        // Pass response headers back to the client
        Header[] headerArrayResponse = httpMethodProxyRequest.getResponseHeaders();
        for (Header header : headerArrayResponse) {
            if (header.getName().equals("Transfer-Encoding") && header.getValue().equals("chunked")
                    || header.getName().equals("Content-Encoding") && header.getValue().equals("gzip") || // don't copy gzip header
                    header.getName().equals("WWW-Authenticate")) { // don't copy WWW-Authenticate header so browser doesn't prompt on failed basic auth
                // proxy servlet does not support chunked encoding
            } else {
                httpServletResponse.setHeader(header.getName(), header.getValue());
            }
        }

        List<Header> responseHeaders = Arrays.asList(headerArrayResponse);

        if (isBodyParameterGzipped(responseHeaders)) {
            debug("GZipped: true");
            int length = 0;

            if (!followRedirects && intProxyResponseCode == HttpServletResponse.SC_MOVED_TEMPORARILY) {
                String gz = httpMethodProxyRequest.getResponseHeader(STRING_LOCATION_HEADER).getValue();
                httpServletResponse.setStatus(HttpServletResponse.SC_OK);
                intProxyResponseCode = HttpServletResponse.SC_OK;
                httpServletResponse.setHeader(STRING_LOCATION_HEADER, gz);
            } else {
                final byte[] bytes = ungzip(httpMethodProxyRequest.getResponseBody());
                length = bytes.length;
                response = new ByteArrayInputStream(bytes);
            }
            httpServletResponse.setContentLength(length);
        }

        // Send the content to the client
        debug("Received status code: " + intProxyResponseCode, "Response: " + response);

        //httpServletResponse.getWriter().write(response);
        copy(response, httpServletResponse.getOutputStream());
    }

    /**
     * Copy the contents of the given InputStream to the given OutputStream.
     * Closes both streams when done.
     *
     * @param in  the stream to copy from
     * @param out the stream to copy to
     * @return the number of bytes copied
     * @throws java.io.IOException in case of I/O errors
     */
    public static long copy(InputStream in, OutputStream out) throws IOException {
        try {
            int byteCount = 0;
            byte[] buffer = new byte[FOUR_KB];
            int bytesRead;
            while ((bytesRead = in.read(buffer)) != -1) {
                out.write(buffer, 0, bytesRead);
                byteCount += bytesRead;
            }
            out.flush();
            return byteCount;
        } finally {
            close(in);
            close(out);
        }
    }

    /**
     * Close the given stream if the stream is not null.
     *
     * @param s The stream
     */

    public static void close(InputStream s) {
        if (s != null) {
            try {
                s.close();
            } catch (Exception e) {
                debug("Error closing stream: " + e.getMessage());
            }
        }
    }

    /**
     * Close the given stream if the stream is not null.
     *
     * @param s The stream
     */

    public static void close(OutputStream s) {
        if (s != null) {
            try {
                s.close();
            } catch (Exception e) {
                debug("Error closing stream: " + e.getMessage());
            }
        }
    }

    /**
     * The response body will be assumed to be gzipped if the GZIP header has been set.
     *
     * @param responseHeaders of response headers
     * @return true if the body is gzipped
     */
    private boolean isBodyParameterGzipped(List<Header> responseHeaders) {
        for (Header header : responseHeaders) {
            if (header.getValue().equals("gzip")) {
                return true;
            }
        }
        return false;
    }

    /**
     * A highly performant ungzip implementation. Do not refactor this without taking new timings.
     * See ElementTest in ehcache for timings
     *
     * @param gzipped the gzipped content
     * @return an ungzipped byte[]
     * @throws java.io.IOException when something bad happens
     */
    private byte[] ungzip(final byte[] gzipped) throws IOException {
        final GZIPInputStream inputStream = new GZIPInputStream(new ByteArrayInputStream(gzipped));
        ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream(gzipped.length);
        final byte[] buffer = new byte[FOUR_KB];
        int bytesRead = 0;
        while (bytesRead != -1) {
            bytesRead = inputStream.read(buffer, 0, FOUR_KB);
            if (bytesRead != -1) {
                byteArrayOutputStream.write(buffer, 0, bytesRead);
            }
        }
        byte[] ungzipped = byteArrayOutputStream.toByteArray();
        inputStream.close();
        byteArrayOutputStream.close();
        return ungzipped;
    }

    public String getServletInfo() {
        return "GWT Proxy Servlet";
    }

    /**
     * Retrieves all of the headers from the servlet request and sets them on
     * the proxy request
     *
     * @param httpServletRequest     The request object representing the client's
     *                               request to the servlet engine
     * @param httpMethodProxyRequest The request that we are about to send to
     *                               the proxy host
     */
    @SuppressWarnings("unchecked")
    private void setProxyRequestHeaders(HttpServletRequest httpServletRequest, HttpMethod httpMethodProxyRequest) {
        // Get an Enumeration of all of the header names sent by the client
        Enumeration enumerationOfHeaderNames = httpServletRequest.getHeaderNames();
        while (enumerationOfHeaderNames.hasMoreElements()) {
            String stringHeaderName = (String) enumerationOfHeaderNames.nextElement();
            if (stringHeaderName.equalsIgnoreCase(STRING_CONTENT_LENGTH_HEADER_NAME)) {
                continue;
            }
            // As per the Java Servlet API 2.5 documentation:
            //      Some headers, such as Accept-Language can be sent by clients
            //      as several headers each with a different value rather than
            //      sending the header as a comma separated list.
            // Thus, we get an Enumeration of the header values sent by the client
            Enumeration enumerationOfHeaderValues = httpServletRequest.getHeaders(stringHeaderName);
            while (enumerationOfHeaderValues.hasMoreElements()) {
                String stringHeaderValue = (String) enumerationOfHeaderValues.nextElement();
                // In case the proxy host is running multiple virtual servers,
                // rewrite the Host header to ensure that we get content from
                // the correct virtual server
                if (stringHeaderName.equalsIgnoreCase(STRING_HOST_HEADER_NAME)) {
                    stringHeaderValue = getProxyHostAndPort();
                }
                Header header = new Header(stringHeaderName, stringHeaderValue);
                // Set the same header on the proxy request
                httpMethodProxyRequest.setRequestHeader(header);
            }
        }
    }

    /**
     * Retrieves all of the cookies from the servlet request and sets them on
     * the proxy request
     *
     * @param httpServletRequest     The request object representing the client's
     *                               request to the servlet engine
     * @param httpMethodProxyRequest The request that we are about to send to
     *                               the proxy host
     */
    @SuppressWarnings("unchecked")
    private void setProxyRequestCookies(HttpServletRequest httpServletRequest, HttpMethod httpMethodProxyRequest) {
        // Get an array of all of all the cookies sent by the client
        Cookie[] cookies = httpServletRequest.getCookies();
        if (cookies == null) {
            return;
        }

        for (Cookie cookie : cookies) {
            cookie.setDomain(stringProxyHost);
            cookie.setPath(httpServletRequest.getServletPath());
            httpMethodProxyRequest.setRequestHeader("Cookie",
                    cookie.getName() + "=" + cookie.getValue() + "; Path=" + cookie.getPath());
        }
    }

    // Accessors

    private String getProxyURL(HttpServletRequest httpServletRequest) {
        // Set the protocol to HTTP
        String protocol = (httpServletRequest.isSecure()) ? "https://" : "http://";
        String stringProxyURL = protocol + this.getProxyHostAndPort();

        // simply use whatever servlet path that was part of the request as opposed to getting a preset/configurable proxy path
        if (!removePrefix) {
            stringProxyURL += httpServletRequest.getServletPath();
        }
        stringProxyURL += "/";

        // Handle the path given to the servlet
        String pathInfo = httpServletRequest.getPathInfo();
        if (pathInfo != null && pathInfo.startsWith("/")) {
            if (stringProxyURL != null && stringProxyURL.endsWith("/")) {
                // avoid double '/'
                stringProxyURL += pathInfo.substring(1);
            }
        } else {
            stringProxyURL += httpServletRequest.getPathInfo();
        }
        // Handle the query string
        if (httpServletRequest.getQueryString() != null) {
            stringProxyURL += "?" + httpServletRequest.getQueryString();
        }

        return stringProxyURL;
    }

    private String getProxyHostAndPort() {
        if (this.getProxyPort() == 80) {
            return this.getProxyHost();
        } else {
            return this.getProxyHost() + ":" + this.getProxyPort();
        }
    }

    protected String getProxyHost() {
        return this.stringProxyHost;
    }

    protected void setProxyHost(String stringProxyHostNew) {
        this.stringProxyHost = stringProxyHostNew;
    }

    protected int getProxyPort() {
        return this.intProxyPort;
    }

    protected void setFollowRedirects(boolean followRedirects) {
        this.followRedirects = followRedirects;
    }

    protected void setProxyPort(int intProxyPortNew) {
        this.intProxyPort = intProxyPortNew;
    }

    protected String getProxyPath() {
        return this.stringProxyPath;
    }

    protected void setProxyPath(String stringProxyPathNew) {
        this.stringProxyPath = stringProxyPathNew;
    }

    protected void setRemovePrefix(boolean removePrefix) {
        this.removePrefix = removePrefix;
    }

    protected int getMaxFileUploadSize() {
        return this.intMaxFileUploadSize;
    }

    protected void setMaxFileUploadSize(int intMaxFileUploadSizeNew) {
        this.intMaxFileUploadSize = intMaxFileUploadSizeNew;
    }

    private static void debug(String... msg) {
        for (String m : msg) {
            System.out.println("[DEBUG] " + m);
        }
    }
}