FunctionAuthnConfiguration

Current File(s): conf/authn/function-authn-config.xml, conf/authn/authn.properties (V4.1+)
Format: Native Spring, Properties (V4.1+)

1 Overview
2 Enabling Module (V4.1+)
3 General Configuration
- 3.1 Use of Cookies
4 Reference

Overview

The authn/Function login flow is an extension point that allows authentication to be handled by a deployer-supplied Function object, which can be written in Java, a scripting language, etc. It simplifies authoring certain kinds of custom login flows (essentially it provides the "flow" part) and potentially simplifies some MultiFactorAuthnConfiguration scenarios by moving some of the logic into a separate component.

Enabling Module (V4.1+)

For V4.1+, configuring and using this feature requires that you first enable the "idp.authn.Function" module if it isn't already enabled. Systems upgraded from older releases generally come pre-enabled due to the prior state of the configuration tree.

(Windows)
C:\opt\shibboleth-idp> bin\module.bat -t idp.authn.Function || bin\module.bat -e idp.authn.Function
 
(Other)
$ bin/module.sh -t idp.authn.Function || bin/module.sh -e idp.authn.Function

General Configuration

Use authn/function-authn-config.xml to configure this flow.

Most of the flow configuration is in authn/function-authn-config.xml but some generic settings applicable to all login flows are in authn/authn.properties.

The core of the flow is a required bean named shibboleth.authn.Function.ResultLookupStrategy, of type Function<ProfileRequestContext,Object>

If the Function returns a null, then authentication fails (this is how to signal a controlled failure). Otherwise, the Function can return a String (the username), a Principal, or a Subject, and the system will construct an appropriate AuthenticationResult around whatever is returned.

Use of Cookies

Since a common use case is to be able to read and write cookies, note that there's already a component that handles this called a CookieManager. There are built-in objects of this type that will reuse standard properties controlling cookie domain, path, flags, etc. and that's usually the best way to do things. Simply inject an instance of shibboleth.CookieManager or shibboleth.PersistentCookieManager into a Java-based Function implementation, or as a customObject-ref property of a bean inheriting from shibboleth.ContextFunctions.Scripted or shibboleth.ContextFunctions.Expression, to use it to read and write cookies for you.

Reference

The beans defined, or expected to be defined, in authn/function-authn-config.xml are:

Bean ID / Type	Default	Function

Bean ID / Type

Default

Function

shibboleth.authn.Function.resultLookupStrategy

Function<ProfileRequestContext,Object>

A function to produce the authentication result (see above)

shibboleth.authn.Function.resultCachingPredicate

Predicate<ProfileRequestContext>

An optional bean that can be defined to control whether to preserve the authentication result in an IdP session

shibboleth.authn.Function.addDefaultPrincipals

Boolean

true

Whether to add the content of the supportedPrincipals property of the underlying flow descriptor to the resulting Subject