org.springframework.security.web

Class FilterChainProxy

java.lang.Object

org.springframework.web.filter.GenericFilterBean

org.springframework.security.web.FilterChainProxy

All Implemented Interfaces:

javax.servlet.Filter, org.springframework.beans.factory.Aware, org.springframework.beans.factory.BeanNameAware, org.springframework.beans.factory.DisposableBean, org.springframework.beans.factory.InitializingBean, org.springframework.context.EnvironmentAware, org.springframework.core.env.EnvironmentCapable, org.springframework.web.context.ServletContextAware

public class FilterChainProxy
extends org.springframework.web.filter.GenericFilterBean

Delegates Filter requests to a list of Spring-managed filter beans. As of version 2.0, you shouldn't need to explicitly configure a 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 <security:http /> namespace configuration options.

The FilterChainProxy is linked into the servlet container filter chain by adding a standard Spring DelegatingFilterProxy declaration in the application web.xml file.

Configuration

As of version 3.1, FilterChainProxy is configured using a list of SecurityFilterChain instances, each of which contains a 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 <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:

  <bean id="myfilterChainProxy" class="org.springframework.security.web.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>
 

The names "filter1", "filter2", "filter3" should be the bean names of 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.

Request Handling

Each possible pattern that the FilterChainProxy should service must be entered. The first match for a given request will be used to define all of the Filters that apply to that request. This means you must put most specific matches at the top of the list, and ensure all Filters that should apply for a given matcher are entered against the respective entry. The FilterChainProxy will not iterate through the remainder of the map entries to locate additional Filters.

FilterChainProxy respects normal handling of Filters that elect not to call Filter.doFilter(javax.servlet.ServletRequest, javax.servlet.ServletResponse, javax.servlet.FilterChain) , in that the remainder of the original or FilterChainProxy-declared filter chain will not be called.

Request Firewalling

An HttpFirewall instance is used to validate incoming requests and create a wrapped request which provides consistent path values for matching against. See StrictHttpFirewall, 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.

Note that this means that you must use the Spring Security filters in combination with a FilterChainProxy if you want this protection. Don't define them explicitly in your web.xml file.

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 reset method will be called. With the default implementation this means that the original values of servletPath and pathInfo will be returned thereafter, instead of the modified ones used for security pattern matching.

Since this additional wrapping functionality is performed by the 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 Filter instance.

Filter Lifecycle

Note the Filter lifecycle mismatch between the servlet container and IoC container. As described in the DelegatingFilterProxy Javadocs, we recommend you allow the IoC container to manage the lifecycle instead of the servlet container. FilterChainProxy does not invoke the standard filter lifecycle methods on any filter beans that you add to the application context.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	FilterChainProxy.FilterChainValidator

Constructor Summary

Constructors

Constructor and Description
FilterChainProxy()
FilterChainProxy(java.util.List<SecurityFilterChain> filterChains)
FilterChainProxy(SecurityFilterChain chain)

Method Summary

Modifier and Type	Method and Description
void	afterPropertiesSet()
void	doFilter(javax.servlet.ServletRequest request, javax.servlet.ServletResponse response, javax.servlet.FilterChain chain)
java.util.List<SecurityFilterChain>	getFilterChains()
java.util.List<javax.servlet.Filter>	getFilters(java.lang.String url) Convenience method, mainly for testing.
void	setFilterChainValidator(FilterChainProxy.FilterChainValidator filterChainValidator) Used (internally) to specify a validation strategy for the filters in each configured chain.
void	setFirewall(HttpFirewall firewall) Sets the "firewall" implementation which will be used to validate and wrap (or potentially reject) the incoming requests.
java.lang.String	toString()

Methods inherited from class org.springframework.web.filter.GenericFilterBean

addRequiredProperty, createEnvironment, destroy, getEnvironment, getFilterConfig, getFilterName, getServletContext, init, initBeanWrapper, initFilterBean, setBeanName, setEnvironment, setServletContext

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

FilterChainProxy

public FilterChainProxy()

FilterChainProxy

public FilterChainProxy(SecurityFilterChain chain)

FilterChainProxy

public FilterChainProxy(java.util.List<SecurityFilterChain> filterChains)

Method Detail

afterPropertiesSet

public void afterPropertiesSet()

Specified by:

afterPropertiesSet in interface org.springframework.beans.factory.InitializingBean

Overrides:

afterPropertiesSet in class org.springframework.web.filter.GenericFilterBean

doFilter

public void doFilter(javax.servlet.ServletRequest request,
                     javax.servlet.ServletResponse response,
                     javax.servlet.FilterChain chain)
              throws java.io.IOException,
                     javax.servlet.ServletException

Throws:

java.io.IOException

javax.servlet.ServletException

getFilters

public java.util.List<javax.servlet.Filter> getFilters(java.lang.String url)

Convenience method, mainly for testing.

Parameters:

url - the URL

Returns:

matching filter list

getFilterChains

public java.util.List<SecurityFilterChain> getFilterChains()

Returns:

the list of SecurityFilterChains which will be matched against and applied to incoming requests.

setFilterChainValidator

public void setFilterChainValidator(FilterChainProxy.FilterChainValidator filterChainValidator)

Used (internally) to specify a validation strategy for the filters in each configured chain.

Parameters:

filterChainValidator - the validator instance which will be invoked on during initialization to check the FilterChainProxy instance.

setFirewall

public void setFirewall(HttpFirewall firewall)

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.

Parameters:

firewall -

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object