Implement pre-flow-init action to prepare server-specific settings

OSF server-specific settings such as OSF URLs need to be configured
at the very beginning of the login flow so that ThymeLeaf templates
can be rendered correctly across the flow state machine.

Previously, it was configured at the start of the non-interactive
action where any rendering attempt before it would fail with empty
pages rendered. This is fixed now by overriding the login flow init
process. A pre-init action with what we did in the non-interactive
action before is injected onto the top of the start action list.

Author: cslzchen

src/main/java/io/cos/cas/osf/web/config/OsfCasSupportActionsConfiguration.java

@@ -3,6 +3,7 @@
 import io.cos.cas.osf.dao.JpaOsfDao;
 import io.cos.cas.osf.web.flow.login.OsfDefaultLoginPreparationAction;
 import io.cos.cas.osf.web.flow.login.OsfInstitutionLoginPreparationAction;
+import io.cos.cas.osf.web.flow.login.OsfCasPreInitialFlowSetupAction;
 import io.cos.cas.osf.web.flow.login.OsfPrincipalFromNonInteractiveCredentialsAction;
 
 import org.apereo.cas.CentralAuthenticationService;
@@ -22,7 +23,6 @@
 import org.springframework.webflow.execution.Action;
 
 import java.util.LinkedHashMap;
-import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 
@@ -48,7 +48,6 @@ public class OsfCasSupportActionsConfiguration extends CasSupportActionsConfigur
     @Qualifier("initialAuthenticationAttemptWebflowEventResolver")
     private ObjectProvider<CasDelegatingWebflowEventResolver> initialAuthenticationAttemptWebflowEventResolver;
 
-
     @Autowired
     @Qualifier("adaptiveAuthenticationPolicy")
     private ObjectProvider<AdaptiveAuthenticationPolicy> adaptiveAuthenticationPolicy;
@@ -60,6 +59,16 @@ public class OsfCasSupportActionsConfiguration extends CasSupportActionsConfigur
     @Autowired
     private ObjectProvider<JpaOsfDao> jpaOsfDao;
 
+    /**
+     * Bean configuration for {@link OsfCasPreInitialFlowSetupAction}.
+     *
+     * @return the initialized action
+     */
+    @Bean
+    public Action osfCasPreInitialFlowSetupAction() {
+        return new OsfCasPreInitialFlowSetupAction(casProperties.getAuthn().getOsfUrl());
+    }
+
     /**
      * Bean configuration for {@link OsfPrincipalFromNonInteractiveCredentialsAction}.
      *

src/main/java/io/cos/cas/osf/web/flow/configurer/OsfCasLoginWebflowConfigurer.java

@@ -26,6 +26,7 @@
 import org.springframework.context.ConfigurableApplicationContext;
 import org.springframework.webflow.core.collection.MutableAttributeMap;
 import org.springframework.webflow.definition.registry.FlowDefinitionRegistry;
+import org.springframework.webflow.engine.ActionList;
 import org.springframework.webflow.engine.ActionState;
 import org.springframework.webflow.engine.Flow;
 import org.springframework.webflow.engine.History;
@@ -66,6 +67,13 @@ public OsfCasLoginWebflowConfigurer(
         super(flowBuilderServices, flowDefinitionRegistry, applicationContext, casProperties);
     }
 
+    @Override
+    protected void createInitialFlowActions(final Flow flow) {
+        final ActionList startActionList = flow.getStartActionList();
+        startActionList.add(createEvaluateAction(OsfCasWebflowConstants.ACTION_ID_OSF_PRE_INITIAL_FLOW_SETUP));
+        super.createInitialFlowActions(flow);
+    }
+
     @Override
     protected void createDefaultViewStates(final Flow flow) {
         super.createDefaultViewStates(flow);
@@ -438,5 +446,4 @@ protected void createInstitutionLoginView(final Flow flow) {
                 OsfCasWebflowConstants.VIEW_ID_INSTITUTION_SSO_INIT
         );
     }
-
 }

src/main/java/io/cos/cas/osf/web/flow/login/OsfCasPreInitialFlowSetupAction.java

@@ -0,0 +1,39 @@
+package io.cos.cas.osf.web.flow.login;
+
+import io.cos.cas.osf.configuration.model.OsfUrlProperties;
+
+import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+
+import org.springframework.webflow.action.AbstractAction;
+import org.springframework.webflow.execution.Event;
+import org.springframework.webflow.execution.RequestContext;
+
+import javax.validation.constraints.NotNull;
+import java.util.Optional;
+
+/**
+ * This is {@link OsfCasPreInitialFlowSetupAction}.
+ *
+ * @author Longze Chen
+ * @since 20.2.0
+ */
+@RequiredArgsConstructor
+@Slf4j
+public class OsfCasPreInitialFlowSetupAction extends AbstractAction {
+
+    private static final String OSF_URL_FLOW_PARAMETER = "osfUrl";
+
+    @NotNull
+    private final OsfUrlProperties osfUrlProperties;
+
+    @Override
+    protected Event doExecute(final RequestContext context) {
+        OsfUrlProperties osfUrl = Optional.of(context).map(requestContext
+                -> (OsfUrlProperties) requestContext.getFlowScope().get(OSF_URL_FLOW_PARAMETER)).orElse(null);
+        if (osfUrl == null) {
+            context.getFlowScope().put(OSF_URL_FLOW_PARAMETER, osfUrlProperties);
+        }
+        return success();
+    }
+}

src/main/java/io/cos/cas/osf/web/flow/login/OsfPrincipalFromNonInteractiveCredentialsAction.java

@@ -80,7 +80,6 @@
 import java.util.Date;
 import java.util.List;
 import java.util.Map;
-import java.util.Optional;
 
 /**
  * This is {@link OsfPrincipalFromNonInteractiveCredentialsAction}.
@@ -265,12 +264,6 @@ protected Credential constructCredentialsFromRequest(final RequestContext contex
 
     @Override
     protected Event doPreExecute(final RequestContext context) throws Exception {
-        // Put server-specific OSF URLs into the flow scope
-        OsfUrlProperties osfUrl = Optional.of(context).map(requestContext
-                -> (OsfUrlProperties) requestContext.getFlowScope().get(OSF_URL_FLOW_PARAMETER)).orElse(null);
-        if (osfUrl == null) {
-            context.getFlowScope().put(OSF_URL_FLOW_PARAMETER, osfUrlProperties);
-        }
         // super.doPreExecute() calls constructCredentialsFromRequest() whose exception must be caught and returned as a flow event
         try {
             return super.doPreExecute(context);

src/main/java/io/cos/cas/osf/web/flow/support/OsfCasWebflowConstants.java

@@ -10,6 +10,8 @@
 
 public interface OsfCasWebflowConstants {
 
+    String ACTION_ID_OSF_PRE_INITIAL_FLOW_SETUP = "osfCasPreInitialFlowSetupAction";
+
     String ACTION_ID_OSF_DEFAULT_LOGIN_CHECK = "osfDefaultLoginCheckAction";
 
     String STATE_ID_OSF_DEFAULT_LOGIN_CHECK = "osfDefaultLoginCheck";