/**
* Copyright (c) 2008-2009 Yahoo! Inc.
* All rights reserved.
* The copyrights to the contents of this file are licensed under the MIT License (http://www.opensource.org/licenses/mit-license.php)
*/
package hudson.security.csrf;
import hudson.model.Hudson;
import java.io.IOException;
import java.util.Enumeration;
import java.util.logging.Logger;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Checks for and validates crumbs on requests that cause state changes, to
* protect against cross site request forgeries.
*
* @author dty
*/
public class CrumbFilter implements Filter {
/**
* Because servlet containers generally don't specify the ordering of the initialization
* (and different implementations indeed do this differently --- See HUDSON-3878),
* we cannot use Hudson to the CrumbIssuer into CrumbFilter eagerly.
*/
public CrumbIssuer getCrumbIssuer() {
Hudson h = Hudson.getInstance();
if(h==null) return null; // before Hudson is initialized?
return h.getCrumbIssuer();
}
public void init(FilterConfig filterConfig) throws ServletException {
}
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
CrumbIssuer crumbIssuer = getCrumbIssuer();
if (crumbIssuer == null || !(request instanceof HttpServletRequest)) {
chain.doFilter(request, response);
return;
}
HttpServletRequest httpRequest = (HttpServletRequest) request;
String crumbFieldName = crumbIssuer.getDescriptor().getCrumbRequestField();
String crumbSalt = crumbIssuer.getDescriptor().getCrumbSalt();
if ("POST".equals(httpRequest.getMethod())) {
String crumb = httpRequest.getHeader(crumbFieldName);
boolean valid = false;
if (crumb == null) {
Enumeration<?> paramNames = request.getParameterNames();
while (paramNames.hasMoreElements()) {
String paramName = (String) paramNames.nextElement();
if (crumbFieldName.equals(paramName)) {
crumb = request.getParameter(paramName);
break;
}
}
}
if (crumb != null) {
if (crumbIssuer.validateCrumb(httpRequest, crumbSalt, crumb)) {
valid = true;
} else {
LOGGER.warning("Found invalid crumb " + crumb +
". Will check remaining parameters for a valid one...");
}
}
// Multipart requests need to be handled by each handler.
if (valid || isMultipart(httpRequest)) {
chain.doFilter(request, response);
} else {
LOGGER.warning("No valid crumb was included in request for " + httpRequest.getRequestURI() + ". Returning " + HttpServletResponse.SC_FORBIDDEN + ".");
HttpServletResponse httpResponse = (HttpServletResponse) response;
httpResponse.sendError(HttpServletResponse.SC_FORBIDDEN,"No valid crumb was included in the request");
}
} else {
chain.doFilter(request, response);
}
}
protected static boolean isMultipart(HttpServletRequest request) {
if (request == null) {
return false;
}
String contentType = request.getContentType();
if (contentType == null) {
return false;
}
String[] parts = contentType.split(";");
if (parts.length == 0) {
return false;
}
for (int i = 0; i < parts.length; i++) {
if ("multipart/form-data".equals(parts[i])) {
return true;
}
}
return false;
}
/**
* {@inheritDoc}
*/
public void destroy() {
}
private static final Logger LOGGER = Logger.getLogger(CrumbFilter.class.getName());
}