package org.exist.http.servlets;
/*
* eXist Open Source Native XML Database
* Copyright (C) 2001-07 The eXist Project
* http://exist-db.org
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*
* $Id$
*/
import org.apache.log4j.Logger;
import org.exist.Namespaces;
import org.exist.source.FileSource;
import org.exist.xmldb.CollectionImpl;
import org.exist.xmldb.XQueryService;
import org.exist.xmldb.XmldbURI;
import org.exist.xquery.functions.request.RequestModule;
import org.exist.xquery.functions.response.ResponseModule;
import org.exist.xquery.functions.session.SessionModule;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.xmldb.api.DatabaseManager;
import org.xmldb.api.base.Collection;
import org.xmldb.api.base.Database;
import org.xmldb.api.base.ResourceSet;
import org.xmldb.api.base.XMLDBException;
import org.xmldb.api.modules.XMLResource;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.File;
import java.io.IOException;
import java.net.URISyntaxException;
import java.util.*;
/**
* Servlet to redirect HTTP requests. The request is passed to an XQuery whose return value
* determines where the request will be redirected to. The query should return a single XML element:
*
* <pre>
* <exist:dispatch xmlns:exist="http://exist.sourceforge.net/NS/exist"
* path="/preview.xql" servlet-name="MyServlet" redirect="path">
* <exist:add-parameter name="new-param" value="new-param-value"/>
* </exist:dispatch>
* </pre>
*
* The element should have one of three attributes: <em>path</em>, <em>servlet-name</em> or
* <em>redirect</em>.
*
* If the servlet-name attribute is present, the request will be forwarded to the named servlet
* (name as specified in web.xml). Alternatively, path can point to an arbitrary resource. It can be either absolute or relative.
* Relative paths are resolved relative to the original request.
*
* The request is forwarded via {@link javax.servlet.RequestDispatcher#forward(javax.servlet.ServletRequest, javax.servlet.ServletResponse)}.
* Contrary to HTTP forwarding, there is no additional roundtrip to the client. It all happens on
* the server. The client will not notice the redirect.
*
* When forwarding to other servlets, the fields in {@link javax.servlet.http.HttpServletRequest} will be
* updated to point to the new, redirected URI. However, the original request URI is stored in the
* request attribute org.exist.forward.request-uri.
*
* If present, the "redirect" attribute causes the server to send a redirect request to the client, which will usually respond
* with a new request to the redirected location. Note that this is quite different from a forwarding via RequestDispatcher,
* which is completely transparent to the client.
*
* RedirectorServlet takes a single parameter in web.xml: "xquery". This parameter should point to an
* XQuery script. It should be relative to the current web context.
*
* <pre>
* <servlet>
* <servlet-name>RedirectorServlet</servlet-name>
* <servlet-class>org.exist.http.servlets.RedirectorServlet</servlet-class>
*
* <init-param>
* <param-name>xquery</param-name>
* <param-value>dispatcher.xql</param-value>
* </init-param>
* </servlet>
*
* <servlet-mapping>
* <servlet-name>RedirectorServlet</servlet-name>
* <url-pattern>/wiki/*</url-pattern>
* </servlet-mapping>
* </pre>
*/
public class RedirectorServlet extends HttpServlet {
private static final Logger LOG = Logger.getLogger(RedirectorServlet.class);
public final static String DEFAULT_USER = "guest";
public final static String DEFAULT_PASS = "guest";
public final static XmldbURI DEFAULT_URI = XmldbURI.EMBEDDED_SERVER_URI.append(XmldbURI.ROOT_COLLECTION_URI);
public final static String DRIVER = "org.exist.xmldb.DatabaseImpl";
private String user = null;
private String password = null;
private XmldbURI collectionURI = null;
private String query = null;
public void init(ServletConfig config) throws ServletException {
super.init(config);
query = config.getInitParameter("xquery");
if (query == null)
throw new ServletException("RedirectorServlet requires a parameter 'xquery'.");
user = config.getInitParameter("user");
if(user == null)
user = DEFAULT_USER;
password = config.getInitParameter("password");
if(password == null)
password = DEFAULT_PASS;
String confCollectionURI = config.getInitParameter("uri");
if(confCollectionURI == null) {
collectionURI = DEFAULT_URI;
} else {
try {
collectionURI = XmldbURI.xmldbUriFor(confCollectionURI);
} catch (URISyntaxException e) {
throw new ServletException("Invalid XmldbURI for parameter 'uri': "+e.getMessage(),e);
}
}
try {
Class driver = Class.forName(DRIVER);
Database database = (Database)driver.newInstance();
database.setProperty("create-database", "true");
DatabaseManager.registerDatabase(database);
} catch(Exception e) {
String errorMessage="Failed to initialize database driver";
LOG.error(errorMessage,e);
throw new ServletException(errorMessage+": " + e.getMessage(), e);
}
}
protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
if (request.getCharacterEncoding() == null)
try {
request.setCharacterEncoding("UTF-8");
} catch (IllegalStateException e) {
}
// Try to find the XQuery
String qpath = getServletContext().getRealPath(query);
File f = new File(qpath);
if (!(f.canRead() && f.isFile()))
throw new ServletException("Cannot read XQuery source from " + f.getAbsolutePath());
FileSource source = new FileSource(f, "UTF-8", true);
try {
// Prepare and execute the XQuery
Collection collection = DatabaseManager.getCollection(collectionURI.toString(), user, password);
XQueryService service = (XQueryService) collection.getService("XQueryService", "1.0");
if(!((CollectionImpl)collection).isRemoteCollection()) {
service.declareVariable(RequestModule.PREFIX + ":request", new HttpRequestWrapper(request, "UTF-8", "UTF-8"));
service.declareVariable(ResponseModule.PREFIX + ":response", new HttpResponseWrapper(response));
service.declareVariable(SessionModule.PREFIX + ":session", new HttpSessionWrapper(request.getSession( false )));
}
ResourceSet result = service.execute(source);
String redirectTo = null;
String servletName = null;
String path = null;
RequestWrapper modifiedRequest = null;
// parse the query result element
if (result.getSize() == 1) {
XMLResource resource = (XMLResource) result.getResource(0);
Node node = resource.getContentAsDOM();
if (node.getNodeType() == Node.DOCUMENT_NODE)
node = ((Document) node).getDocumentElement();
if (node.getNodeType() != Node.ELEMENT_NODE) {
response.sendError(HttpServletResponse.SC_BAD_REQUEST,
"Redirect XQuery should return an XML element. Received: " + resource.getContent());
return;
}
Element elem = (Element) node;
if (!(Namespaces.EXIST_NS.equals(elem.getNamespaceURI()) && "dispatch".equals(elem.getLocalName())))
{
response.sendError(HttpServletResponse.SC_BAD_REQUEST,
"Redirect XQuery should return an element <exist:dispatch>. Received: " + resource.getContent());
return;
}
if (elem.hasAttribute("path"))
path = elem.getAttribute("path");
else if (elem.hasAttribute("servlet-name"))
servletName = elem.getAttribute("servlet-name");
else if (elem.hasAttribute("redirect"))
redirectTo = elem.getAttribute("redirect");
else {
response.sendError(HttpServletResponse.SC_BAD_REQUEST,
"Element <exist:dispatch> should either provide an attribute 'path' or 'servlet-name'. Received: " +
resource.getContent());
return;
}
// Check for add-parameter elements etc.
if (elem.hasChildNodes()) {
node = elem.getFirstChild();
while (node != null) {
if (node.getNodeType() == Node.ELEMENT_NODE && Namespaces.EXIST_NS.equals(node.getNamespaceURI())) {
elem = (Element) node;
if ("add-parameter".equals(elem.getLocalName())) {
if (modifiedRequest == null)
modifiedRequest = new RequestWrapper(request);
modifiedRequest.addParameter(elem.getAttribute("name"), elem.getAttribute("value"));
}
}
node = node.getNextSibling();
}
}
}
if (redirectTo != null) {
// directly redirect to the specified URI
response.sendRedirect(redirectTo);
return;
}
// Get a RequestDispatcher, either from the servlet context or the request
RequestDispatcher dispatcher;
if (servletName != null && servletName.length() > 0)
dispatcher = getServletContext().getNamedDispatcher(servletName);
else {
LOG.debug("Dispatching to " + path);
dispatcher = getServletContext().getRequestDispatcher(path);
if (dispatcher == null)
dispatcher = request.getRequestDispatcher(path);
}
if (dispatcher == null) {
response.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR,
"Could not create a request dispatcher. Giving up.");
return;
}
if (modifiedRequest != null)
request = modifiedRequest;
// store the original request URI to org.exist.forward.request-uri
request.setAttribute("org.exist.forward.request-uri", request.getRequestURI());
request.setAttribute("org.exist.forward.servlet-path", request.getServletPath());
// finally, execute the forward
dispatcher.forward(request, response);
} catch (XMLDBException e) {
throw new ServletException("An error occurred while initializing RedirectorServlet: " + e.getMessage(), e);
}
}
private class RequestWrapper extends javax.servlet.http.HttpServletRequestWrapper {
Map addedParams = new HashMap();
private RequestWrapper(HttpServletRequest request) {
super(request);
// copy parameters
for (Enumeration e = request.getParameterNames(); e.hasMoreElements(); ) {
String key = (String) e.nextElement();
String[] value = request.getParameterValues(key);
if (value.length == 1)
addedParams.put(key, value[0]);
else
addedParams.put(key, value);
}
}
public void addParameter(String name, String value) {
addedParams.put(name, value);
}
public String getParameter(String name) {
return (String) addedParams.get(name);
}
public Map getParameterMap() {
return addedParams;
}
public Enumeration getParameterNames() {
Vector v = new Vector();
for (Iterator i = addedParams.keySet().iterator(); i.hasNext(); ) {
String key = (String) i.next();
v.addElement(key);
}
return v.elements();
}
public String[] getParameterValues(String s) {
Object value = addedParams.get(s);
if (value != null) {
if (value instanceof String[])
return (String[]) value;
else
return new String[] { value.toString() };
}
return null;
}
}
}