docs: Document getAuthData()-function, and saml-specific authentication data.

git-svn-id: https://simplesamlphp.googlecode.com/svn/trunk@2767 44740490-163a-0410-bde0-09ae8108e29a

docs/simplesamlphp-sp-api.txt

@@ -195,6 +195,23 @@ The attributes will be returned as an associative array with the name of the att
     print('Hello, ' . htmlspecialchars($name));
 
 
+`getAuthData`
+---------------
+
+    mixed getAuthData(string $name)
+
+Retrieve the specified authentication data for the current session.
+NULL is returned if the user isn't authenticated.
+
+The available authentication data depends on the module used for authentication.
+See the [`saml:SP`](./saml:sp) reference for information about available SAML authentication data.
+
+### Example
+
+    $idp = $auth->getAuthData('saml:sp:IdP');
+    print(You are logged in from: ' . htmlspecialchars($idp));
+
+
 `getLoginURL`
 -------------
 

modules/saml/docs/sp.txt

@@ -42,6 +42,23 @@ All these parameters override the equivalent option from the configuration.
 :   *Note*: SAML 2 specific.
 
 
+Authentication data
+-------------------
+
+Some SAML-specific attributes are available to the application after authentication.
+To retrieve these attributes, the application can use the `getAuthData()`-function from the [SP API](./simplesamlphp-sp-api).
+The following attributes are available:
+
+`saml:sp:IdP`
+:   The entityID of the IdP the user is authenticated against.
+
+`saml:sp:NameID`
+:   The NameID the user was issued by the IdP.
+    This is an associative array with the various fields from the NameID.
+
+`saml:sp:SessionIndex`
+:   The SessionIndex we received from the IdP.
+
 
 Examples
 --------