Java filters were introduced in the Java Servlet specification version 2.3. A filter intercepts requests and responses to transform or use the information. Filters typically do not themselves create responses but instead provide universal functions that can be "attached" to any type of servlet page.
Since the filter chain is responsible for request handling in Magnolia, the default chain illustrates how filters are used to process requests. This document provides minimal information on filters. For more, see Request processing and filters and the filters package.
Don't change the filter order
Magnolia handles incoming requests to display a page through its own filter chain. Filters in the chain are executed in the order in which they are declared until a filter decides that it can fulfill the request.
When editing properties in the filter chain be careful. Always test the changes on test environment before applying it to production.
For instance, if you add a Voter to a filter with an erroneous regular expression, you won't be able to access admincentral anymore. (In such case you have to use Groovy Rescue App).
The first filter in the filter chain is
. This filter initializes
MgnlContext and configures MDC logging.
MgnlContext is local to the request and available on every further filter. The context provides a lot of useful functions, see
The job of the
ContentTypeFilter is to initialize the non-content related attributes of the
It's created and populated with:
- Character encoding
- Original URI
- Original URL
- Query string
AggregationState is accessible using
Content-Type header is not set by
ContentTypeFilter anymore. The MIME type was incorrectly set according to the request extension. It is now the responsibility of renderers/servlets to set the correct content type. For instance
sets the content type.
is a personalization filter that detects request cookies and adds them as traits to the aggregation state.
is a GeoIP trait filter that detects the user's country using the IP address of the request for personalization. It adds the country to the aggregation state as a trait. If a GET parameter
with an IP address is supplied, this address is used to resolve the country, which is stored in the
is a visitor trait filter that detects the type of visitor based on the current user and cookies for personalization.
visitorCookies can be configured for returning and registered users.
(Applicable to the cookie name nodes, i.e. to "returning", "registered" and "new" in the above examples.)
optional, default is
A security setting that prevents cookies from being read by potentially malicious code.
optional, default is
Setting the property to
Only used by the STK.
DeviceDetectionFilter detects the type of device requesting content. Device detection is done using the Mobile Detect API.
CosMultipartRequestFilter checks to see if there are any binary uploads such as form attachments in the request, extracts the binaries and persists them in the JCR.
UnicodeNormalizationFilter normalizes the current URI to the NFC form that is used internally.
RegistrationFilter checks the validity of the registration of a DX Core installation and delegates to the registration form so that the user can enter the license key. The license is also checked in other parts of the code such as in the STK.
Handles incoming login requests and delegates to login handlers. The handlers are configured under this filter. LoginFilter checks to verify that user credentials have been authenticated so that only authenticated users can be made active users. Magnolia uses JAAS for authentication. For more information see Security.
The activation filter handles incoming activation requests. This filter is the receiving part of the activation process.
The activation filter is implemented using
from the Activation module. In DX Core,
(included in the ) extends module
ReceiveFilter to provide transaction-related communications with syndicators.
Here's an example of how to use the bypass feature to avoid specific filters. This configuration will only handle requests where the URI starts with
To increase the performance of the site
replaces text type responses with the gzipped response. The trick in this filter is that it passes a ResponseWrapper instead of the response object it got in the
doFilter(..) call to the filter chain. After all the following filters have been executed, content is extracted from the ResponseWrapper, gzipped and written to the original response.
MultiChannelFilter resolves the channel to use by considering variations of the set channel. Resulting site gets set in ExtendedAggregationState .
MultiSiteFilter is a DX Core filter. It detects which site definition should be used. The filter makes site related properties available in the AggregationState .
SiteMergeFilter merges channel variations with the site definition. Configurations under this filter override configuration done in the site definition. The filter sets the site definition in the aggregation state. In the Community Edition, this filter sets the site in the aggregation state. In DX Core, the multisite filter can also set the site.
checks to see if the logout attribute
mgnlLogout is set as a request parameter. If this flag is found, the user will be logged out and the filter chain will restart with the first filter.
handles 401 and 403 HTTP response codes and
AccessDeniedExceptions. The filter renders an appropriate "login form" that can consist of a redirect or anything else.
HttpClientCallbacks with different configuration and behavior can be configured for this filter.
Here is the client callback configuration for the Travel demo members area redirect and login form.
Both callback classes implement the HttpClientCallback interface and support their own configuration properties. A custom callback should implement this interface.
- RedirectClientCallback redirects to a configured path or URL. This is useful, for example in single sign-on (SSO) context where the login screen is handled by a different application, or to hide the login form from a public instance using a fronting server configuration.
renders a login form using Freemarker and the template configured with
AbstractHttpClientCallback provides a number of filtering capabilities:
url. Current request URL decoded and without the context path.
originalUrl. Original request URL decoded and without the context path, but not modified by any filter.
For example, in a multisite installation for the request
The Multisite filter removes the first-level node name from the URL.
The methods provided by
AbstractHttpClientCallback are also provided by the utility class
CsrfSecurityFilter checks the HTTP referer header to ensure that the request is not a cross-site request forgery attack. When a possible CSRF attack is detected the system serves a 400 Bad Request status to the browser. Magnolia also logs a security warning to the audit log.
If you access Magnolia with a script, set the referer header in your script to ensure the script can access Magnolia. Similarly, if you embed Magnolia content into a different website, disable the CSRF filter or add a voter (see below) that bypasses the CSRF filter for any requests coming from the trusted URL.
The CSRF security filter causes a request to fail if:
The referer header is empty
The host part of the referer header does not match the requested host.
Bypassing the filter
You can bypass the CSRF security filter with a voter.
By default, the filter is bypassed if:
- The requested URL does not start with
/.magnolia. Only AdminCentral URLs are vulnerable to CSRF attacks. Other URLs are not checked.
- The user is not authenticated for AdminCentral access. Only authenticated requests are vulnerable to CSRF attacks.
- The request does not have query parameters.
- The requested resource is somewhere in AdminCentral. Vaadin has its own CSRF protection so Magnolia hands the responsibility over to Vaadin.
You can create your own whitelist of referrer domains or URIs using a voter. The filter is bypassed for the whitelisted referrers. In this example, we bypass the filter for any requests referred by
Voter node. Name the node for example
Fully-qualified voter class name.
Header you are checking such as
Domain or URI pattern compliant to SimpleUrlPattern . The pattern must be present in the header for the filter to be bypassed.
CSRF and Internet Explorer
Some builds of Internet Explorer don't send the HTTP request header referrer when submitting a form or when opening a popup. If the referrer is not in the HTTP request header,
CsrfSecurityFilter#handlePossibleCsrf interprets the request as potential CSRF attack which forces the user to log in on the popup. (See
Getting issue details...
). To overcome this issue, add voter class
to bypass CsrfSecurityFilter for Internet Explorer.
Below the node
allowed you can add a list of regular expressions to match the HTTP header userAgent. In the example above we have bypassed Internet Explorer 6 and 11.
To ensure the filter is bypassed, make sure to have at least one property on the node
allowed with a value which will match the userAgent of the browser for which you want to bypass the filter. (For Internet Explorer 11, the userAgent might be Mozilla/5.0 (Windows NT 6.3; Trident/7.0; rv:11.0) like Gecko.)
Always test changes on test environment before applying it to a production system. When adding an erroneous regular expression - you won't access admin central anymore. (In such case you have to use Groovy Rescue App).
grants or denies permission to a site when the site is requested through a particular domain name. For example, if you only grant access to the
travel site through
www.travel.com, no other URL can be used to access the content. When a user tries to access one site's content through another site's domain name, the system displays a HTTP 404 error (page not found). See Cross-site security
checks to see if the active user has permission to access the requested URI. In DX Core,
(included in the ) extends module
UriSecurityFilter to provide site aware functionality.
The following constraints are considered in finding the permissions of the user:
- URI ACLs of the user's roles
- URI ACLs of the user's groups' roles
- Permissions on IP addresses
If the user does not have the permission to access the URI then JAAS will provide a login form. This default behavior of the URI security filter can be changed in JAAS configuration.
You can configure your own login form in the URI security filter to replace the default Magnolia login form. The form is configured in
/server/filters/securityCallback/clientCallbacks. Here is an example of a custom form used to grant public users access to a restricted members area. Authentication is delegated to the custom form when a particular URI is accessed.
RangeSupportFilter adds support for ranged requests. Ranged requests is used by iPhone and some other clients to stream videos. In contrast to Android phones, iPhone does not support any other method of streaming videos.
i18n content support
I18nContentSupportFilter detects the requested locale and sets the locale in the aggregation state. The filter rewrites the internal current URI, whether virtual or not. It does not rewrite the URI displayed to the user, however. See Language.
CacheFilter manages the Magnolia cache.
The cache filter checks if a requested resource is already stored in the cache to avoid recreation of the resource. If the resource is in the cache, then it will be written to the response and the filter chain stops. If the resource is not found in the cache, then a
ResponseWrapper, which not only writes to the "standard" response but also saves the response, is passed to the chain. After the filters that follow have been executed (and the requested resource created), the content is extracted from the response wrapper and stored in the cache.
The cache filter is part of Cache coreand the respective configuration can be found in the module configuration.
VirtualUriFilter checks if the requested URI matches a configured URI pattern and executes the URI mapping.
Servlets filter chain
The servlets configured in modules are installed in Magnolia's servlets filter chain using the
as the implementing filter class. If the servlet mapping matches the URI, then the
service(..) method of the servlet is called. See Registering a servlet for more.
CMS filter chain
Finally, we arrive at the filter chain which does the page rendering and delivery. The filters are grouped in this filter chain so they share a co-bypass definition.
handles access to different workspaces. By default, Magnolia is connected with the
website workspace. Therefore a request URI is interpreted as the path to a node in the
website workspace. If you want to address nodes in other workspaces you need to specify a repository mapping in
Whereas the URI security filter checks permissions on the URI, ContentSecurityFilter checks if the current user has permission to access the requested content resource. The following constraints are considered in finding the permissions of the user:
- Workspace-specific ACLs of the user's roles
- Workspace-specific ACLs of the user's groups' roles
If the user does not have permission to the resource, then JAAS will provide a login form. This default behavior of the content security filter can be changed in JAAS configuration.
AggregatorFilter analyses the request and stores the results in the AggregationState . After this filter, every value the aggregation state can have is known.
is a personalization filter that wraps variant nodes. The filter tries to resolve a variant from the current node (from
AggregationState) using all available traits stored in the
TraitCollector and wraps it accordingly, if required. It only uses
PersonalizationNodeWrapper if a variant was resolved. Non-variants are not wrapped.
optional , default is
If set to
Deprecated since Magnolia 5.1. This filter is no longer used. Its function is now handled in part by the page editor and in part by the
InterceptFilter handles administrative requests from AdminCentral like
- Sort nodes
- Delete a node
- Switch to preview
executes the component model before template rendering. The filter looks for a request parameter containing the UUID of the component to execute. The model can send output in which case page rendering is skipped, or return a URI prefixed by
Finally, RenderingFilter is responsible for delivering the requested resource. If the requested resource is data, such as a file, then the data is just copied to the response.
The rendering filter is terminal, meaning it ends the filter chain and filtering process. If no filter before it has been able to fulfill the request and the rendering filter cannot find the page either, then a 404 "Page not found" error is returned. This is the default behavior.
You can change the behavior by adding a
terminateChain property under the rendering filter and setting it to
false. When a request for a page such as
/home/some/page is received and no such page exists in the JCR, your own servlets can have a go at fulfilling the request. The default value for the
terminateChain property is true.
Restricting access to resources
Access to resources is defined in the
/modules/resources/config/resourceFilter filter. By default, the filter allows access to resources as follows:
css, map, js, htm(l), ico, woff(2), ttf, svg, gif, jp(e)g, tiff, bmp
- when located in the '
- when located in the '
Adding HTTP headers
The AddHeadersFilter implementation class allows configuration of a filter for adding HTTP headers to enable, for example, Cross-origin resource sharing (CORS). The parameters configured in this filter are added to the HTTP header if the filter is triggered. You can restrict the filter's scope by adding and configuring a
bypasses node to it. For details please refer to the Magnolia main filter page.
Example configuration for CORS
The example allows CORS with header types
Accept, with the
GET method, and from any origin:
X-Requested-With, Content-Type, Accept
The position of a filter within the filter chain matters. The appropriate position depends on the use case.
When using this filter to enable cross-origin resource sharing (CORS) - place it after
Properties used in the example:
required, deafult is
Enables or disables the filter.
Class that implements the filter: AddHeadersFilter.
Headers allowed for the request.
The HTTP verbs that are allowed to make the request.
The origin of the request (URL/host).
If you need a custom filter, please read Custom filters.