Spring Boot JWT token role-based authorization issue - spring-boot

Question

So, what I'm trying to achieve is role-based authorization using JWT token. This is tutorial that I'm extending: https://auth0.com/blog/implementing-jwt-authentication-on-spring-boot/
Now, my problems starts there: if (user != null) { This is a place where I need to fetch user from database and load its roles. This is not working, and null pointer exception is thrown.
I'm sure that there is user in database, and I'm sure that UserService is working - I am using it in different place and works fine.
Looking forward for your answers!
public class JWTAuthorizationFilter extends BasicAuthenticationFilter {
public JWTAuthorizationFilter(AuthenticationManager authManager) {
super(authManager);
}
#Override
protected void doFilterInternal(HttpServletRequest req, HttpServletResponse res, FilterChain chain) throws IOException, ServletException {
String header = req.getHeader(HEADER_STRING);
if (header == null || !header.startsWith(TOKEN_PREFIX)) {
chain.doFilter(req, res);
return;
}
UsernamePasswordAuthenticationToken authentication = getAuthentication(req);
SecurityContextHolder.getContext().setAuthentication(authentication);
chain.doFilter(req, res);
}
private UsernamePasswordAuthenticationToken getAuthentication(HttpServletRequest request) {
String token = request.getHeader(HEADER_STRING);
if (token != null) {
// parse the token.
String user = JWT.require(Algorithm.HMAC512(SECRET.getBytes()))
.build()
.verify(token.replace(TOKEN_PREFIX, ""))
.getSubject(); //można też getClaims jeśli są w tokenie
if (user != null) {
UserService userService = new UserService();
ApplicationUser applicationUser = userService.getByUsername(user);
Set<Role> roles = applicationUser.getRoles();
List<GrantedAuthority> grantedAuths = new ArrayList<>();
roles.forEach((role) -> {
grantedAuths.add(new SimpleGrantedAuthority(role.getName()));
});
return new UsernamePasswordAuthenticationToken(user, null, grantedAuths);
}
return null;
}
return null;
}
}
This is UserService class:
import java.util.List;
#Service
#Component
public class UserService {
#Autowired
private ApplicationUserRepository applicationUserRepository;
public ApplicationUser getByUsername(String username) {
return applicationUserRepository.findByUsername(username);
}
}
This is Repository class:
public interface ApplicationUserRepository extends JpaRepository<ApplicationUser, Long> {
ApplicationUser findByUsername(String username);
}
And this is error:
2020-05-26 21:32:47.241 ERROR 1892 --- [nio-8080-exec-1] o.a.c.c.C.[.[.[/].[dispatcherServlet] : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception
java.lang.NullPointerException: null
at example.service.UserService.getByUsername(UserService.java:20) ~[classes/:na]
at example.Security.JWTAuthorizationFilter.getAuthentication(JWTAuthorizationFilter.java:74) ~[classes/:na]
at example.Security.JWTAuthorizationFilter.doFilterInternal(JWTAuthorizationFilter.java:49) ~[classes/:na]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.6.RELEASE.jar:5.2.6.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.3.2.RELEASE.jar:5.3.2.RELEASE]
at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:200) ~[spring-security-web-5.3.2.RELEASE.jar:5.3.2.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.3.2.RELEASE.jar:5.3.2.RELEASE]
at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:116) ~[spring-security-web-5.3.2.RELEASE.jar:5.3.2.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.3.2.RELEASE.jar:5.3.2.RELEASE]
at org.springframework.web.filter.CorsFilter.doFilterInternal(CorsFilter.java:92) ~[spring-web-5.2.6.RELEASE.jar:5.2.6.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.6.RELEASE.jar:5.2.6.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.3.2.RELEASE.jar:5.3.2.RELEASE]
at org.springframework.security.web.header.HeaderWriterFilter.doHeadersAfter(HeaderWriterFilter.java:92) ~[spring-security-web-5.3.2.RELEASE.jar:5.3.2.RELEASE]
at org.springframework.security.web.header.HeaderWriterFilter.doFilterInternal(HeaderWriterFilter.java:77) ~[spring-security-web-5.3.2.RELEASE.jar:5.3.2.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.6.RELEASE.jar:5.2.6.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.3.2.RELEASE.jar:5.3.2.RELEASE]
at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:105) ~[spring-security-web-5.3.2.RELEASE.jar:5.3.2.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.3.2.RELEASE.jar:5.3.2.RELEASE]
at org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:56) ~[spring-security-web-5.3.2.RELEASE.jar:5.3.2.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.6.RELEASE.jar:5.2.6.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.3.2.RELEASE.jar:5.3.2.RELEASE]
at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:215) ~[spring-security-web-5.3.2.RELEASE.jar:5.3.2.RELEASE]
at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:178) ~[spring-security-web-5.3.2.RELEASE.jar:5.3.2.RELEASE]
at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:358) ~[spring-web-5.2.6.RELEASE.jar:5.2.6.RELEASE]
at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:271) ~[spring-web-5.2.6.RELEASE.jar:5.2.6.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-5.2.6.RELEASE.jar:5.2.6.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.6.RELEASE.jar:5.2.6.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-5.2.6.RELEASE.jar:5.2.6.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.6.RELEASE.jar:5.2.6.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-5.2.6.RELEASE.jar:5.2.6.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.6.RELEASE.jar:5.2.6.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:541) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:373) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:868) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1590) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128) ~[na:na]
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628) ~[na:na]
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
at java.base/java.lang.Thread.run(Thread.java:830) ~[na:na]

Answer 1

Your UserService is not properly injected and therefore not correctly initialized, thus giving the null pointer exception. Below are a few things that you can do:
In your JWTAuthorization Filter, inject user service:
public class JWTAuthorizationFilter extends BasicAuthenticationFilter {
private final IUserService UserService; // create IUserService as below
public JWTAuthorizationFilter(AuthenticationManager authManager, IUserService userService) {
super(authManager);
this.userService = userService;
}
(...)
}
Remove UserService userService = new UserService(); from your getAuthentication method because you already have the userService instance, injected through the constructor.
In your WebSecurity class (or whatever class that implements WebSecurityConfigurerAdapter), do the same, injecting IUserService:
private final IUserService userService;
public WebSecurity(IUserService userService)
{
this.userService = userService;
}
In the same class (WebSecurity) you override the configure method adding the JWTAuthorizationFilter. Now you have to pass the userService.
.addFilter(new JWTAuthorizationFilter(authenticationManager(), userService))
Finally, create an interface IUserService
public interface IUserService{
ApplicationUser getByUsername(String username);
}
Change your UserService to implement IUserService (remove #Component because it's actually a #Service).
#Service
public class UserService implements IUserService{
// keep it as is
}
Note: You could name your interface as UserService and the concrete implementation as UserServiceImpl, because you will be always using the interface and not the concrete implementation, so it reads better.
Bonus: difference between #Component and #Service annotations https://www.baeldung.com/spring-component-repository-service