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FilterChainProxy.java
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FilterChainProxy.java
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/* Copyright 2004, 2005, 2006 Acegi Technology Pty Limited
*
* 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.springframework.security.web;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.security.core.context.SecurityContextHolder;
import org.springframework.security.web.firewall.DefaultHttpFirewall;
import org.springframework.security.web.firewall.FirewalledRequest;
import org.springframework.security.web.firewall.HttpFirewall;
import org.springframework.security.web.util.matcher.RequestMatcher;
import org.springframework.security.web.util.UrlUtils;
import org.springframework.web.filter.DelegatingFilterProxy;
import org.springframework.web.filter.GenericFilterBean;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.*;
/**
* Delegates {@code Filter} requests to a list of Spring-managed filter beans.
* As of version 2.0, you shouldn't need to explicitly configure a {@code FilterChainProxy} bean in your application
* context unless you need very fine control over the filter chain contents. Most cases should be adequately covered
* by the default {@code <security:http />} namespace configuration options.
* <p>
* The {@code FilterChainProxy} is linked into the servlet container filter chain by adding a standard
* Spring {@link DelegatingFilterProxy} declaration in the application {@code web.xml} file.
*
* <h2>Configuration</h2>
* <p>
* As of version 3.1, {@code FilterChainProxy} is configured using a list of {@link SecurityFilterChain} instances,
* each of which contains a {@link RequestMatcher} and a list of filters which should be applied to matching requests.
* Most applications will only contain a single filter chain, and if you are using the namespace, you don't have to
* set the chains explicitly. If you require finer-grained control, you can make use of the {@code <filter-chain>}
* namespace element. This defines a URI pattern and the list of filters (as comma-separated bean names) which should be
* applied to requests which match the pattern. An example configuration might look like this:
*
* <pre>
<bean id="myfilterChainProxy" class="org.springframework.security.util.FilterChainProxy">
<constructor-arg>
<util:list>
<security:filter-chain pattern="/do/not/filter*" filters="none"/>
<security:filter-chain pattern="/**" filters="filter1,filter2,filter3"/>
</util:list>
</constructor-arg>
</bean>
* </pre>
*
* The names "filter1", "filter2", "filter3" should be the bean names of {@code Filter} instances defined in the
* application context. The order of the names defines the order in which the filters will be applied. As shown above,
* use of the value "none" for the "filters" can be used to exclude a request pattern from the security filter chain
* entirely. Please consult the security namespace schema file for a full list of available configuration options.
*
* <h2>Request Handling</h2>
* <p>
* Each possible pattern that the {@code FilterChainProxy} should service must be entered.
* The first match for a given request will be used to define all of the {@code Filter}s that apply to that
* request. This means you must put most specific matches at the top of the list, and ensure all {@code Filter}s
* that should apply for a given matcher are entered against the respective entry.
* The {@code FilterChainProxy} will not iterate through the remainder of the map entries to locate additional
* {@code Filter}s.
* <p>
* {@code FilterChainProxy} respects normal handling of {@code Filter}s that elect not to call {@link
* javax.servlet.Filter#doFilter(javax.servlet.ServletRequest, javax.servlet.ServletResponse,
* javax.servlet.FilterChain)}, in that the remainder of the original or {@code FilterChainProxy}-declared filter
* chain will not be called.
*
* <h3>Request Firewalling</h3>
*
* An {@link HttpFirewall} instance is used to validate incoming requests and create a wrapped request which provides
* consistent path values for matching against. See {@link DefaultHttpFirewall}, for more information on the type of
* attacks which the default implementation protects against. A custom implementation can be injected to provide
* stricter control over the request contents or if an application needs to support certain types of request which
* are rejected by default.
* <p>
* Note that this means that you must use the Spring Security filters in combination with a {@code FilterChainProxy}
* if you want this protection. Don't define them explicitly in your {@code web.xml} file.
* <p>
* {@code FilterChainProxy} will use the firewall instance to obtain both request and response objects which will be
* fed down the filter chain, so it is also possible to use this functionality to control the functionality of the
* response. When the request has passed through the security filter chain, the {@code reset} method will be called.
* With the default implementation this means that the original values of {@code servletPath} and {@code pathInfo} will
* be returned thereafter, instead of the modified ones used for security pattern matching.
* <p>
* Since this additional wrapping functionality is performed by the {@code FilterChainProxy}, we don't recommend that
* you use multiple instances in the same filter chain. It shouldn't be considered purely as a utility for wrapping
* filter beans in a single {@code Filter} instance.
*
* <h2>Filter Lifecycle</h2>
* <p>
* Note the {@code Filter} lifecycle mismatch between the servlet container and IoC
* container. As described in the {@link DelegatingFilterProxy} Javadocs, we recommend you allow the IoC
* container to manage the lifecycle instead of the servlet container. {@code FilterChainProxy} does not invoke the
* standard filter lifecycle methods on any filter beans that you add to the application context.
*
* @author Carlos Sanchez
* @author Ben Alex
* @author Luke Taylor
* @author Rob Winch
*/
public class FilterChainProxy extends GenericFilterBean {
//~ Static fields/initializers =====================================================================================
private static final Log logger = LogFactory.getLog(FilterChainProxy.class);
//~ Instance fields ================================================================================================
private final static String FILTER_APPLIED = FilterChainProxy.class.getName().concat(".APPLIED");
private List<SecurityFilterChain> filterChains;
private FilterChainValidator filterChainValidator = new NullFilterChainValidator();
private HttpFirewall firewall = new DefaultHttpFirewall();
//~ Methods ========================================================================================================
public FilterChainProxy() {
}
public FilterChainProxy(SecurityFilterChain chain) {
this(Arrays.asList(chain));
}
public FilterChainProxy(List<SecurityFilterChain> filterChains) {
this.filterChains = filterChains;
}
@Override
public void afterPropertiesSet() {
filterChainValidator.validate(this);
}
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
throws IOException, ServletException {
boolean clearContext = request.getAttribute(FILTER_APPLIED) == null;
if(clearContext) {
try {
request.setAttribute(FILTER_APPLIED, Boolean.TRUE);
doFilterInternal(request, response, chain);
} finally {
SecurityContextHolder.clearContext();
request.removeAttribute(FILTER_APPLIED);
}
} else {
doFilterInternal(request, response, chain);
}
}
private void doFilterInternal(ServletRequest request, ServletResponse response, FilterChain chain)
throws IOException, ServletException {
FirewalledRequest fwRequest = firewall.getFirewalledRequest((HttpServletRequest) request);
HttpServletResponse fwResponse = firewall.getFirewalledResponse((HttpServletResponse) response);
List<Filter> filters = getFilters(fwRequest);
if (filters == null || filters.size() == 0) {
if (logger.isDebugEnabled()) {
logger.debug(UrlUtils.buildRequestUrl(fwRequest) +
(filters == null ? " has no matching filters" : " has an empty filter list"));
}
fwRequest.reset();
chain.doFilter(fwRequest, fwResponse);
return;
}
VirtualFilterChain vfc = new VirtualFilterChain(fwRequest, chain, filters);
vfc.doFilter(fwRequest, fwResponse);
}
/**
* Returns the first filter chain matching the supplied URL.
*
* @param request the request to match
* @return an ordered array of Filters defining the filter chain
*/
private List<Filter> getFilters(HttpServletRequest request) {
for (SecurityFilterChain chain : filterChains) {
if (chain.matches(request)) {
return chain.getFilters();
}
}
return null;
}
/**
* Convenience method, mainly for testing.
*
* @param url the URL
* @return matching filter list
*/
public List<Filter> getFilters(String url) {
return getFilters(firewall.getFirewalledRequest((new FilterInvocation(url, null).getRequest())));
}
/**
* Sets the mapping of URL patterns to filter chains.
*
* The map keys should be the paths and the values should be arrays of {@code Filter} objects.
* It's VERY important that the type of map used preserves ordering - the order in which the iterator
* returns the entries must be the same as the order they were added to the map, otherwise you have no way
* of guaranteeing that the most specific patterns are returned before the more general ones. So make sure
* the Map used is an instance of {@code LinkedHashMap} or an equivalent, rather than a plain {@code HashMap}, for
* example.
*
* @param filterChainMap the map of path Strings to {@code List<Filter>}s.
* @deprecated Use the constructor which takes a {@code List<SecurityFilterChain>} instead.
*/
@Deprecated
public void setFilterChainMap(Map<RequestMatcher, List<Filter>> filterChainMap) {
filterChains = new ArrayList<SecurityFilterChain>(filterChainMap.size());
for (Map.Entry<RequestMatcher,List<Filter>> entry : filterChainMap.entrySet()) {
filterChains.add(new DefaultSecurityFilterChain(entry.getKey(), entry.getValue()));
}
}
/**
* Returns a copy of the underlying filter chain map. Modifications to the map contents
* will not affect the FilterChainProxy state.
*
* @return the map of path pattern Strings to filter chain lists (with ordering guaranteed).
*
* @deprecated use the list of {@link SecurityFilterChain}s instead
*/
@Deprecated
public Map<RequestMatcher, List<Filter>> getFilterChainMap() {
LinkedHashMap<RequestMatcher, List<Filter>> map = new LinkedHashMap<RequestMatcher, List<Filter>>();
for (SecurityFilterChain chain : filterChains) {
map.put(((DefaultSecurityFilterChain)chain).getRequestMatcher(), chain.getFilters());
}
return map;
}
/**
* @return the list of {@code SecurityFilterChain}s which will be matched against and
* applied to incoming requests.
*/
public List<SecurityFilterChain> getFilterChains() {
return Collections.unmodifiableList(filterChains);
}
/**
* Used (internally) to specify a validation strategy for the filters in each configured chain.
*
* @param filterChainValidator the validator instance which will be invoked on during initialization
* to check the {@code FilterChainProxy} instance.
*/
public void setFilterChainValidator(FilterChainValidator filterChainValidator) {
this.filterChainValidator = filterChainValidator;
}
/**
* Sets the "firewall" implementation which will be used to validate and wrap (or potentially reject) the
* incoming requests. The default implementation should be satisfactory for most requirements.
*
* @param firewall
*/
public void setFirewall(HttpFirewall firewall) {
this.firewall = firewall;
}
public String toString() {
StringBuilder sb = new StringBuilder();
sb.append("FilterChainProxy[");
sb.append("Filter Chains: ");
sb.append(filterChains);
sb.append("]");
return sb.toString();
}
//~ Inner Classes ==================================================================================================
/**
* Internal {@code FilterChain} implementation that is used to pass a request through the additional
* internal list of filters which match the request.
*/
private static class VirtualFilterChain implements FilterChain {
private final FilterChain originalChain;
private final List<Filter> additionalFilters;
private final FirewalledRequest firewalledRequest;
private final int size;
private int currentPosition = 0;
private VirtualFilterChain(FirewalledRequest firewalledRequest, FilterChain chain, List<Filter> additionalFilters) {
this.originalChain = chain;
this.additionalFilters = additionalFilters;
this.size = additionalFilters.size();
this.firewalledRequest = firewalledRequest;
}
public void doFilter(ServletRequest request, ServletResponse response) throws IOException, ServletException {
if (currentPosition == size) {
if (logger.isDebugEnabled()) {
logger.debug(UrlUtils.buildRequestUrl(firewalledRequest)
+ " reached end of additional filter chain; proceeding with original chain");
}
// Deactivate path stripping as we exit the security filter chain
this.firewalledRequest.reset();
originalChain.doFilter(request, response);
} else {
currentPosition++;
Filter nextFilter = additionalFilters.get(currentPosition - 1);
if (logger.isDebugEnabled()) {
logger.debug(UrlUtils.buildRequestUrl(firewalledRequest) + " at position " + currentPosition + " of "
+ size + " in additional filter chain; firing Filter: '"
+ nextFilter.getClass().getSimpleName() + "'");
}
nextFilter.doFilter(request, response, this);
}
}
}
public interface FilterChainValidator {
void validate(FilterChainProxy filterChainProxy);
}
private class NullFilterChainValidator implements FilterChainValidator {
public void validate(FilterChainProxy filterChainProxy) {
}
}
}