/*
* File: PEP.java
*
* Copyright 2007 Macquarie E-Learning Centre Of Excellence
*
* 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 org.fcrepo.server.security.xacml.pep.rest;
import java.io.IOException;
import java.util.Map;
import java.util.Set;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.fcrepo.server.security.xacml.pep.AuthzDeniedException;
import org.fcrepo.server.security.xacml.pep.ContextHandler;
import org.fcrepo.server.security.xacml.pep.PEPException;
import org.fcrepo.server.security.xacml.pep.rest.filters.DataResponseWrapper;
import org.fcrepo.server.security.xacml.pep.rest.filters.ObjectsFilter;
import org.fcrepo.server.security.xacml.pep.rest.filters.ObjectsRESTFilterMatcher;
import org.fcrepo.server.security.xacml.pep.rest.filters.ParameterRequestWrapper;
import org.fcrepo.server.security.xacml.pep.rest.filters.RESTFilter;
import org.fcrepo.server.security.xacml.pep.rest.filters.ResponseHandlingRESTFilter;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.sun.xacml.ctx.RequestCtx;
import com.sun.xacml.ctx.ResponseCtx;
import com.sun.xacml.ctx.Result;
/**
* This is the PEP for the REST interface.
*
* @author nishen@melcoe.mq.edu.au
*/
public final class PEP
implements Filter {
private static final Logger logger =
LoggerFactory.getLogger(PEP.class);
private Map<String, RESTFilter> m_filters;
private ObjectsRESTFilterMatcher m_objectsRESTFilterMatcher;
private ContextHandler m_ctxHandler = null;
public PEP(ObjectsRESTFilterMatcher objectsRESTFilterMatcher, Map<String, RESTFilter> filters ) throws PEPException {
m_objectsRESTFilterMatcher = objectsRESTFilterMatcher;
m_filters = filters;
}
/*
* (non-Javadoc)
* @see javax.servlet.Filter#doFilter(javax.servlet.ServletRequest,
* javax.servlet.ServletResponse, javax.servlet.FilterChain)
*/
@Override
public void doFilter(ServletRequest request,
ServletResponse response,
FilterChain chain) throws IOException,
ServletException {
// if a response has already been committed, bypass this filter...
if (response.isCommitted()) {
if (logger.isDebugEnabled()) {
logger.debug("Response has already been committed. Bypassing PEP.");
}
// continuing the chain once auth has failed causes errors. Short
// circuiting the path here.
// remove this if it causes problems
// chain.doFilter(request, response);
return;
}
// Need to make sure we are dealing with HttpServlets
if (!(request instanceof HttpServletRequest)
|| !(response instanceof HttpServletResponse)) {
logger.error("Servlets are not HttpServlets!");
throw new ServletException("Servlets are not HttpServlets!");
}
ServletOutputStream out = null;
ParameterRequestWrapper req = null;
HttpServletResponse res = (HttpServletResponse)response;
// the request and response context
RequestCtx reqCtx = null;
ResponseCtx resCtx = null;
String uri = ((HttpServletRequest) request).getRequestURI();
String servletPath = ((HttpServletRequest) request).getServletPath();
if (logger.isDebugEnabled()) {
logger.debug("Incoming URI: {}", uri);
logger.debug("Incoming servletPath: {}", servletPath);
}
// Fix-up for direct web.xml servlet mappings for:
// /objects/nextPID and /objects/nextPID.xml
// (so servlet path will be different in these cases)
// FIXME: we don't support .xml any more? but included as the servlet mapping is still specified
if (uri.endsWith("/nextPID") || uri.endsWith("/nextPID.xml")) {
servletPath = "/objects";
}
// get the filter (or null if no filter)
RESTFilter filter = m_filters.get(servletPath);
if (filter != null && logger.isDebugEnabled())
logger.debug("obtaining filter: {}", filter.getClass().getName());
if(ObjectsFilter.class.isInstance(filter)) { // go find the ObjectHandler
HttpServletRequest httpRequest = (HttpServletRequest)request;
filter = this.m_objectsRESTFilterMatcher.getObjectsHandler(httpRequest);
if (filter == null) {
logger.error("No FeSL REST objects handler found for \"{}\"", httpRequest.getPathInfo());
throw new ServletException(new PEPException("No FeSL REST objects handler found for " + servletPath));
}
}
try {
// handle the request if we have a filter
if (filter != null) {
// substitute our own request object that manages parameters
try {
req = new ParameterRequestWrapper((HttpServletRequest) request);
} catch (Exception e) {
throw new PEPException(e);
}
logger.debug("Filtering URI: [{}] with: [{}]" , req.getRequestURI(), filter.getClass().getName());
if(ResponseHandlingRESTFilter.class.isInstance(filter)) {
// substitute our own response object that captures the data
res = new DataResponseWrapper(((HttpServletResponse) response));
// get a handle for the original OutputStream
out = response.getOutputStream();
logger.debug("Filtering will include post-processing the response");
}
reqCtx = filter.handleRequest(req, res);
if (reqCtx != null) {
resCtx = m_ctxHandler.evaluate(reqCtx);
enforce(resCtx);
}
// pass the request along to the next chain...
chain.doFilter(req, res);
} else {
// there must always be a filter, even if it is a NOOP
logger.error("No FeSL REST filter found for \"{}\"", servletPath);
throw new PEPException("No FeSL REST filter found for " + servletPath);
}
if(ResponseHandlingRESTFilter.class.isInstance(filter)) {
// handle the response if we have a non-null response handling filter
reqCtx = ((ResponseHandlingRESTFilter)filter).handleResponse(req, res);
if (reqCtx != null) {
resCtx = m_ctxHandler.evaluate(reqCtx);
enforce(resCtx);
}
out.write(((DataResponseWrapper)res).getData());
out.flush();
out.close();
}
} catch (AuthzDeniedException ae) {
if (!res.isCommitted()
&& (req.getRemoteUser() == null || "".equals(req
.getRemoteUser().trim()))) {
loginForm(res);
} else {
denyAccess((HttpServletResponse) response, ae.getMessage());
}
} catch (PEPException pe) {
throw new ServletException("Error evaluating request", pe);
}
}
/*
* (non-Javadoc)
* @see javax.servlet.Filter#init(javax.servlet.FilterConfig)
*/
public void init() throws ServletException {
logger.info("Initialising Servlet Filter: " + PEP.class);
if (m_ctxHandler == null) {
throw new ServletException("Error obtaining ContextHandler");
}
}
@Override
public void init(FilterConfig cfg) throws ServletException {
init();
}
/*
* (non-Javadoc)
* @see javax.servlet.Filter#destroy()
*/
@Override
public void destroy() {
logger.info("Destroying Servlet Filter: " + PEP.class);
m_filters = null;
m_objectsRESTFilterMatcher = null;
m_ctxHandler = null;
}
public void setContextHandler(ContextHandler ctxHandler) {
m_ctxHandler = ctxHandler;
}
/**
* Enforces a decision returned from the PDP.
*
* @param res
* the XACML response
* @throws AuthzDeniedException
*/
private void enforce(ResponseCtx res) throws AuthzDeniedException {
@SuppressWarnings("unchecked")
Set<Result> results = res.getResults();
for (Result r : results) {
if (r.getDecision() != Result.DECISION_PERMIT) {
logger.debug("Denying access: " + r.getDecision());
switch (r.getDecision()) {
case Result.DECISION_DENY:
throw new AuthzDeniedException("Deny");
case Result.DECISION_INDETERMINATE:
throw new AuthzDeniedException("Indeterminate");
case Result.DECISION_NOT_APPLICABLE:
throw new AuthzDeniedException("NotApplicable");
default:
}
}
}
logger.debug("Permitting access!");
}
/**
* Outputs an access denied message.
*
* @param out
* the output stream to send the message to
* @param message
* the message to send
*/
private void denyAccess(HttpServletResponse response, String message)
throws IOException {
StringBuilder sb = new StringBuilder();
sb.append("Fedora: 403 " + message.toUpperCase());
response.reset();
response.setStatus(HttpServletResponse.SC_FORBIDDEN);
response.setContentType("text/plain");
response.setContentLength(sb.length());
ServletOutputStream out = response.getOutputStream();
out.write(sb.toString().getBytes());
out.flush();
out.close();
}
/**
* Sends a 401 error to the browser. This forces a login screen to be
* displayed allowing the user to login.
*
* @param response
* the response to set the headers and status
*/
private void loginForm(HttpServletResponse response) {
response.reset();
response.addHeader("WWW-Authenticate",
"Basic realm=\"!!Fedora Repository Server\"");
response.setStatus(HttpServletResponse.SC_UNAUTHORIZED);
}
}