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/*******************************************************************************
* Copyright (c) 2011, 2017 IBM Corporation and others.
*
* This program and the accompanying materials
* are made available under the terms of the Eclipse Public License 2.0
* which accompanies this distribution, and is available at
* https://www.eclipse.org/legal/epl-2.0/
*
* SPDX-License-Identifier: EPL-2.0
*
* Contributors:
* IBM Corporation - initial API and implementation
*******************************************************************************/
package org.eclipse.help.internal.webapp.servlet;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.io.UnsupportedEncodingException;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.Hashtable;
import java.util.List;
import java.util.Locale;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpServletResponseWrapper;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IConfigurationElement;
import org.eclipse.core.runtime.Platform;
import org.eclipse.help.internal.webapp.HelpWebappPlugin;
import org.eclipse.help.internal.webapp.WebappResources;
import org.eclipse.help.internal.webapp.data.UrlUtil;
import org.eclipse.help.internal.webapp.utils.Utils;
/*
* Class is responsible for implementing security protection. All servlets
* who use the org.eclipse.help.webapp.validatedServlet extension point will
* will be processed for security failures by this class.
*
* Any URL that starts with <path>/vs<etc> will be redirected here for further
* processing. If the validatedServlet extension point has an alias that
* matches the URL passed here, it will finish the processing and return
* results here for validation. If there are no malicious threats detected,
* this class will return the output to the client.
*
*/
public class ValidatorServlet extends HttpServlet {
private static final long serialVersionUID = -3783758607845176051L;
private Hashtable<String, HttpServlet> servletTable = new Hashtable<>();
protected void process(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
String baseURL = req.getRequestURL().toString();
baseURL = baseURL.substring(0, baseURL.indexOf(req.getServletPath()));
Locale locale = UrlUtil.getLocaleObj(req,resp);
String service = req.getRequestURL().toString().substring(
(baseURL).length()+("/vs".length())); //$NON-NLS-1$
try {
HttpServletResponseAdv response = new HttpServletResponseAdv(resp);
HttpServlet servlet = getServlet(service);
ServletConfig config = getServletConfig();
servlet.init(config);
servlet.service(req, response);
if (isSecure(req, response))
response.commitOutput();
} catch(Exception ex) {
String errorMsg = WebappResources.getString("cantCreateServlet", //$NON-NLS-1$
locale, service);
HelpWebappPlugin.logError(errorMsg, ex);
PrintWriter writer = resp.getWriter();
writer.println(errorMsg);
ex.printStackTrace(writer);
resp.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
}
}
private HttpServlet getServlet(String name)
throws CoreException {
HttpServlet servlet = servletTable.get(name);
if (servlet == null) {
IConfigurationElement[] configs =
Platform.getExtensionRegistry().getConfigurationElementsFor(HelpWebappPlugin.PLUGIN_ID+".validatedServlet"); //$NON-NLS-1$
for (IConfigurationElement config2 : configs) {
String alias = config2.getAttribute("alias"); //$NON-NLS-1$
if (alias != null) {
if (isMatch(alias, name)) {
servlet = (HttpServlet)config2.createExecutableExtension("class"); //$NON-NLS-1$
servletTable.put(name, servlet);
break;
}
}
}
}
return servlet;
}
private boolean isMatch(String alias, String name) {
int index = name.indexOf(alias);
if (index == 0) {
int offset = alias.length();
if (name.length() == offset)
return true;
char ch = name.charAt(offset);
if (ch == '/' || ch == '?')
return true;
}
return false;
}
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
process(req, resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
process(req, resp);
}
public boolean isSecure(HttpServletRequest req,HttpServletResponseAdv resp)
throws SecurityException {
Enumeration<String> names = req.getParameterNames();
List<String> values = new ArrayList<>();
List<String> scripts = new ArrayList<>();
while (names.hasMoreElements()) {
String name = names.nextElement();
String val = req.getParameter(name);
values.add(val);
if (replaceAll(val, '+', "").indexOf("<script")>-1) //$NON-NLS-1$ //$NON-NLS-2$
scripts.add(val);
}
if (resp.getWriter() != null) {
String data = resp.getString();
for (int s=0; s < scripts.size(); s++)
if (data.indexOf(scripts.get(s)) > -1)
throw new SecurityException("Potential cross-site scripting detected."); //$NON-NLS-1$
}
return true;
}
public String replaceAll(String str, char remove, String add) {
StringBuilder buffer = new StringBuilder();
for (int s=0; s < str.length(); s++) {
char ch = str.charAt(s);
if (ch == remove)
buffer.append(add);
else
buffer.append(ch);
}
return buffer.toString();
}
private class HttpServletResponseAdv extends HttpServletResponseWrapper {
private HttpServletResponse response;
private ServletPrintWriter writer;
private ServletOutputStream stream;
public HttpServletResponseAdv(HttpServletResponse response) {
super(response);
this.response = response;
}
@Override
public PrintWriter getWriter() {
if (writer == null && stream == null)
writer = new ServletPrintWriter();
return writer;
}
@Override
public ServletOutputStream getOutputStream() throws IOException {
if (stream == null && writer == null)
stream = response.getOutputStream();
return stream;
}
public void commitOutput() throws IOException {
OutputStream os = response.getOutputStream();
InputStream is = getInputStream();
if (is != null) {
Utils.transferContent(is, os);
}
os.flush();
}
public InputStream getInputStream() {
if (writer != null) {
try {
return new ByteArrayInputStream(writer.toString().getBytes(getCharacterEncoding()));
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
}
return null;
}
public String getString() {
if (writer != null)
return writer.toString();
return null;
}
}
}
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