activated interceptor.service.ts;

automatically checks if isAuthenticated():
 - if !isAuthenticated() (token expired), route to login and delete token from sessionStorage;

frontend/src/app/app.module.ts

@@ -4,7 +4,7 @@ import {NgModule} from '@angular/core';
 import {AppRoutingModule} from './app-routing.module';
 import {LandingComponent} from './component/landing/landing.component';
 import {RestService} from './services/rest.service';
-import {HttpClientModule} from '@angular/common/http';
+import {HTTP_INTERCEPTORS, HttpClientModule} from '@angular/common/http';
 import {LoggerModule, NgxLoggerLevel} from 'ngx-logger';
 import {environment} from '../environments/environment';
 import {FormsModule, ReactiveFormsModule} from '@angular/forms';
@@ -30,6 +30,7 @@ import { EditierenComponent } from './component/einstellungen/editieren/editiere
 import {MaterialFileInputModule} from 'ngx-material-file-input';
 import { DialogComponent } from './component/dialog/dialog.component';
 import {MatDialogModule} from '@angular/material/dialog';
+import {InterceptorService} from './services/interceptor.service';
 
 @NgModule({
   declarations: [LandingComponent, LoginComponent, NavigationComponent,
@@ -61,9 +62,9 @@ import {MatDialogModule} from '@angular/material/dialog';
     AuthGuardService,
     RestService,
     JwtHelper,
-    /*{
+    {
       provide: HTTP_INTERCEPTORS, useClass: InterceptorService, multi: true
-    },*/
+    },
 
   ],
   bootstrap: [LandingComponent]

frontend/src/app/services/auth.service.ts

@@ -27,12 +27,18 @@ export class AuthService {
     return sessionStorage.getItem(this.tokenKey);
   }
 
-  // Check whether the token is expired and return
+  /**
-  // true or false
+   *  Check whether the token is expired and return true or false
+   *  If false, removes token from sessionStorage.
+   */
   public isAuthenticated(): boolean {
     const token = sessionStorage.getItem(this.tokenKey);
     if (token) {
-      return !this.jwtHelper.isTokenExpired(token);
+      const authenticated = !this.jwtHelper.isTokenExpired(token);
+      if (!authenticated) {
+        sessionStorage.removeItem(this.tokenKey);
+      }
+      return authenticated;
     } else {
       return false;
     }

frontend/src/app/services/interceptor.service.ts

@@ -1,9 +1,9 @@
-import {HttpEvent, HttpHandler, HttpInterceptor, HttpRequest, HttpResponse} from '@angular/common/http';
+import {HttpEvent, HttpHandler, HttpInterceptor, HttpRequest} from '@angular/common/http';
 import {Injectable} from '@angular/core';
 import {Observable} from 'rxjs';
-import {tap} from 'rxjs/operators';
 import {NGXLogger} from 'ngx-logger';
 import {AuthService} from './auth.service';
+import {Router} from '@angular/router';
 
 @Injectable({
   providedIn: 'root'
@@ -13,41 +13,28 @@ import {AuthService} from './auth.service';
  */
 export class InterceptorService implements HttpInterceptor {
 
-  constructor(private logger: NGXLogger, private authService: AuthService) {
+  constructor(private logger: NGXLogger,
+              private authService: AuthService,
+              private router: Router
+              ) {
   }
 
   /**
-   * Intercepts every HTTP request and for example adds a token
+   * Intercepts every HTTP request.
+   * If the token is invalid (expired) the user is redirected to logout (always).
    * @param req   http request
    * @param next  http response handler
    */
   intercept(req: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
+    // FOR TESTING ONLY - sets an expired token
+    // sessionStorage.setItem('loginToken', 'eyJhbGciOiJIUzI1NiJ9.eyJleHAiOjE2MTk4ODYzNTF9.e83okQ1NHjeO-AxaB3SQP9P5UjOYy-e5DFissDdf2Mo');
 
-    const token = this.authService.getToken();
+    const authenticated = this.authService.isAuthenticated();
-
+    this.logger.debug('isAuthenticated?', authenticated);
-    // the original request is immutable, so we need to clone it
+    if (!this.authService.isAuthenticated()) {
-    req = req.clone({
+      this.logger.debug('token invalid, route to login');
-      setHeaders: {
+      this.router.navigate(['login']).then(() => {});
-        // FIXME e.g. if Bearer is used
-        Authorization: `Bearer ${token}`
     }
-    });
+    return next.handle(req);
-
-    this.logger.debug('Interceptor works');
-
-    // pipe the response observable
-    return next.handle(req).pipe(
-      // perform a side effect for every emission on the source Observable
-      // return an Observable that is identical to the source
-      tap(event => {
-        // check if it is the response message
-        if (event instanceof HttpResponse) {
-          // TODO so something if necessary
-        }
-      }, error => {
-        // TODO handle error here
-        this.logger.error('HTTP Response interception error', error);
-      })
-    );
   }
 }