How to access Principal in controller methods without it declared as argument? - java

I added Spring Security on a Rest API with JWT authentication. Now I need to retrieve some data from the token in every controller method - be it either the username or other information.
Since almost all of my controller methods would need a Principal variable, is there a way to avoid declaring it as an argument to each method?
I once used ObjectProvider to do a similar thing, like:
#RequestScope
#Component
public class MyObj // ...
Usage:
#Component
public class OtherObj {
#Autowired
private ObjectProvider<MyObj> provider;
// ...
#Override
public boolean meth() throws Exception {
MyObj o = provider.getIfAvailable();
// ...
But there I found that if no instance exists, it is created instead of being returned null or an exception being thrown.

You can create one utility class, which provides you the principal.
public static Principal getPrincipal() {
SecurityContext securityContext = SecurityContextHolder.getContext();
return securityContext.getAuthentication().getPrincipal();
}
Ofcourse, here you would need to put the null checks in case the context or authentication is null.

Related

Spring: #RequestScope - annotated method does not get called

In the application I would like to create a request-scoped bean (annotated with #RequestScope) that would represent a user of the application (for authentication OAuth2 is used with the company's own authentication provider based off keycloak; the problem is that the Principal doesn't contain extra information about the permissions this particular user has and they have to be retrieved from another service, which is why I want to have this request-scoped bean that would retrieve fresh permissions on each request).
public class MyApplicationUser {
private final String name;
private final List<Permission> permissions;
/* all-arg constructor, getters */
}
#Configuration
public class UserConfiguration {
private final PermissionService permissionService;
/* constructor, etc */
#Bean
#RequestScope
public MyApplicationUser currentUser(#CurrentSecurityContext(expression = "authentication") OAuth2AuthenticationToken authenticationToken) {
/* call permissionService, map the result and the token details data to MyApplicationUser instance and return it*/
}
}
Although on each request a new instance of MyApplicationUser is created, it is not created by calling the currentUser method (it never gets called), but rather it seems that spring uses the provided constructor and supplies nulls as parameters, which is not what I want. How do I fix that?
P.S. the main class extends SpringBootServletInitializer

Spring Boot : Sharing a bean between different components

I have a bean which I've declared in my bean config as thus:
#Configuration
public class BeanConfig {
#Bean
public MemberDTO getMemberDTO() {
return new MemberDTO();
}
}
When a user calls my service, I use the username and password they've provided to call the endpoint of a different service to get the user's information:
#Component
public class CustomAuthenticationProvider implements AuthenticationProvider {
private static final Logger LOGGER = LogManager.getLogger(CustomAuthenticationProvider.class);
private #Autowired MemberDTO memberDTO;
#Override
public Authentication authenticate(Authentication authentication) throws AuthenticationException {
String loginGeniuneFailMessage = "";
boolean loginGeniuneFail = false;
try {
String username = authentication.getName();
String password = authentication.getCredentials().toString();
String endPoint = credentialsBaseUrl + "/api/login";
HttpResponse<MemberDTO> response_auth = Unirest.get(endPoint)
.basicAuth(username, password)
.header("Accept", "*/*")
.asObject(MemberDTO.class);
int status_auth = response_auth.getStatus();
if (status_auth == 200) {
if (response_auth.getBody() == null) {
LOGGER.info("account validation - could not parse response body to object");
UnirestParsingException ex = response_auth.getParsingError().get();
LOGGER.error("parsing error: ", ex);
} else {
memberDTO = response_auth.getBody();
}
}
...
} catch (Exception ex) {
...
}
}
I want to store the user's information in the memberDTO and use the memberDTO elsewhere in a different component, rather than calling the login API every time:
#Component
public class MemberLogic {
private #Autowired MemberDTO memberDTO;
public ResponseEntity<?> processMemberInformation(WrapperDTO wrapperDTO, BindingResult result) {
if (result.hasFieldErrors()) {
String errors = result.getFieldErrors().stream()
.map(p -> p.getDefaultMessage()).collect(Collectors.joining("\n"));
return ResponseEntity.badRequest().body("An error occured while trying to persist information: " + errors);
}
String name = memberDTO.getName();
...
}
}
The problem now is the "memberDTO.getName()" is returning null, even though this value is being set from the initial API call in CustomAuthenticationProvider.
My questions are: why isn't this working? And is this the best approach to take for something like this?
Thanks.
My questions are: why isn't this working? And is this the best approach to take for something like this?
This doesn't work because Java uses pass-by-value semantics instead of pass-by-reference semantics. What this means is that the statement memberDTO = response_auth.getBody(); does not really make the Spring container start pointing to the MemberDTO returned by response_auth.getBody(). It only makes the memberDTO reference in CustomAuthenticationProvider point to the object in the response. The Spring container still continues to refer to the original MemberDTO object.
One way to fix this would be to define a DAO class that can be used for interacting with DTO instances rather than directly creating a DTO bean :
#Configuration
public class BeanConfig {
#Bean
public MemberDAO getMemberDAO() {
return new MemberDAO();
}
}
CustomAuthenticationProvider can then set the MemberDTO in the MemberDAO by using : memberDAO.setMemberDTO(response_auth.getBody());
Finally, MemberLogic can access the MemberDTO as String name = memberDAO.getMemberDTO().getName();
Note : Instead of returning the MemberDTO from the MemberDAO, the MemberDAO can define a method called getName which extracts the name from the MemberDTO and returns it. (Tell Don't Ask principle). That said and as suggested in the comments, the best practice would be to use a SecurityContext to store the user information.
The problem is, that you can not override a spring bean "content" like this memberDTO = response_auth.getBody(); because it changes only the instance variable for the given bean. (And its also not good because its out of the spring boot context and it overrides only the field dependency for this singleton bean)
You should not use a normal spring bean for holding data (a state). All the spring beans are singleton by default and you could have some concurrency problems.
For this you should use a database, where you write your data or something like a session bean.

Bind Principal to MyCustomUser class as method argument in controller

I know you can get a username easily in a Spring controller by including Principal as a method argument like:
#GetMapping("/username")
#ResponseBody
public String currentUserName(Principal principal) {
return principal.getName();
}
But I am ultimately going to want access to members of a MyCustomUser class that I instantiate from a repository with a findBy method. I can put a helper method in the Controller to do the lookup and return the user based on principal.getName(), but can I go a step further and bind to MyCustomUser directly, like
#GetMapping("/stuff")
#ResponseBody
public String stuff(MyCustomUser user) {
return user.thing();
}
I was looking into creating a converter like (Ref):
#Component
public class PrincipalToMyCustomUserConverter implements Converter<Principal, MyCustomUser> {
private MyCustomUserRepository userRepository;
public PrincipalToApplicationUserConverter(MyCustomUserRepository userRepository) {
this.userRepository = userRepository;
}
#Override
public MyCustomUser convert(Principal source) {
return this.userRepository.findByUsername(source.getName());
}
}
But I don't know if that's an appropriate way to grab the repository, and I don't know how to pass the repository when registering the converter (Ref).
You're correct in that the converter you're proposing is not appropriate. Your converter can convert from an object of type Principal to an object of type MyCustomUser, however, there is no *Principal* by which to convert. The magic behind the principal injection is that Spring actually gets this from the SecurityContextHolder, it is not deserialized from request...though fields present in the request allow Spring to create the Principal. If you truly want to inject MyCustomUser, use a ModelAttribute. ModelAttributes are available to all of your Spring controller methods.
I generally like to keep stuff like this in it's own class, so I would define a class that held this and other #ControllerAdvice in one place, something like this:
#ControllerAdvice
public class SomeControllerAdvice {
#Autowired
private MyCustomUserRepository myCustomUserRepository;
#ModelAttribute
public MyCustomUser getUser(Principal principal) {
return myCustomUserRepository.findByUsername(principal.getName());
}
}
The above should suffice to make MyCustomUser available to all methods. I would note that you probably want a little error handling here, like skip over if principal is null and whatnot, also have your findByUsername method return an Optional so your can address empty returns.
see:
https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/web/bind/annotation/ModelAttribute.html
https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/web/bind/annotation/ControllerAdvice.html

Injecting principal into resource method in RESTEasy with Guice

I am developing a REST API using RESTEasy with Guice and at the moment I am trying to incorporate basic authentication by use of an annotation similar to the #Auth found in Dropwizard. With
#Path("hello")
public class HelloResource {
#GET
#Produces("application/json")
public String hello(#Auth final Principal principal) {
return principal.getUsername();
}
}
the hello resource invocation should be intercepted by some code performing basic authentication using the credentials passed in the Authorization HTTP request header and on success injecting the principal into the method principal parameter. I would also like to be able to pass a list of allowed roles to the annotation, e.g. #Auth("admin").
I really need some advice in what direction to go to achieve this?
I think your best bet would be using an intermediate value within request scope. Assuming that you didn't put HelloResource in singleton scope, you can inject this intermediate value in some ContainerRequestFilter implementation and in your resource, and you can fill it inside this ContainerRequestFilter implementation with all authentication and authorization info you need.
It will look something like this:
// Authentication filter contains code which performs authentication
// and possibly authorization based on the request
#Provider
public class AuthFilter implements ContainerRequestFilter {
private final AuthInfo authInfo;
#Inject
AuthFilter(AuthInfo authInfo) {
this.authInfo = authInfo;
}
#Override
public void filter(ContainerRequestContext requestContext) throws IOException {
// You can check request contents here and even abort the request completely
// Fill authInfo with the data you need
Principal principal = ...; // Ask some other service possibly
authInfo.setPrincipal(principal);
}
}
#Path("hello")
public class HelloResource {
private final AuthInfo authInfo;
#Inject
HelloResource(AuthInfo authInfo) {
this.authInfo = authInfo;
}
#GET
#Produces("application/json")
public String hello() {
// authInfo here will be pre-filled with the principal, assuming
// you didn't abort the request in the filter
return authInfo.getPrincipal().getUsername();
}
}
public class MainModule extends AbstractModule {
#Override
protected void configure() {
bind(AuthFilter.class);
bind(HelloResource.class);
bind(AuthInfo.class).in(RequestScoped.class);
}
}
And even if you did put the resource (or even the filter) in singleton scope for some reason, you can always inject Provider<AuthInfo> instead of AuthInfo.
Update
It seems that I was somewhat wrong in that the filter is by default not in singleton scope. In fact it seem to behave like singleton even though it is not bound as such. It is created upon JAX-RS container startup. Hence you will need to inject Provider<AuthInfo> into the filter. In fact, the container startup will fail if AuthInfo is injected into the filter directly while being bound to request scope. Resource (if not explicitly bound as singleton) will be OK with direct injection though.
I have uploaded working program to github.

Can I use spring DI to inject a session attribute into my POJO of webapplication

I am using the Struts2 framework and have the following method in a POJO class.
public String execute() {
setUserPrincipal();
//do something
someMethod(getUserPrincipal().getLoggedInUserId());
return SUCCESS;
}
the setUserPrincipal() method looks like this
public void setUserPrincipal() {
this.principal = (UserPrincipal) getServletRequest().getSession().getAttribute("principal");
}
Basically it is simply taking a session attribute named "principal" and setting it so that I can find out who the logged in user is. The call to setUserPrincipal() to do this is quite common in most of my POJOs and it also becomes a hassle when testing the method because I have to set a session attribute.
Is there a way to automatically inject the session attribute into the POJO either using Spring or something else?
I've only used Struts2 a bit, but they have an interceptor stack that you can tie to particular actions. You can create your own interceptor that injects the session variable.
public interface UserAware
{
void setUserPrincipal(String principal);
}
// Make your actions implement UserAware
public class MyInterceptor implements Interceptor
{
public String intercept(ActionInvocation inv) throws Exception
{
UserAware action = (UserAware) inv.getAction();
String principal = inv.getInvocationContext().getSession().get("principal");
action.setUserPrincipal(principal);
return inv.invoke();
}
}
Like I said, not much Struts2 experience so this is untested but I think the idea is there.
Don't know about injecting the session, but maybe having a piece of AOP code that sets principal before execute.
Here's some documentation:
http://static.springsource.org/spring/docs/2.5.x/reference/aop.html

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