Spring Oauth2 Client, automatically refresh expired access_token - spring-security

Question

Let me explain my use case.
I need to have a spring boot oauth2 client application (not a resource server As we already have a separate resource server). Also I have following requirements:
For each out going request to resource server, we need to send id_token. (Done by customizing resttemplate).
For any request, no matter if it invokes resource server or not, If access token is expired my application must refresh it automatically (without any user intervention like any popup or redirection.).
If refresh_token is also expired, user must be logged out.
Questions:
For point 2 and 3, I have spent many hours reading documents and code and Stack Overflow but was not able to find the solution (or did not understand). So I decided to put all pieces together which I found on many blogs and documents, and come up with my solution. Below is my solution for point 2.
Can we please have a look to below code and suggest if there could be any problem with this approach?
How to solve point 3 I am thinking of extending solution for point 2 but not sure what code I need to write, can anyone guide me?
/**
*
* #author agam
*
*/
#Component
public class ExpiredTokenFilter extends OncePerRequestFilter {
private static final Logger log = LoggerFactory.getLogger(ExpiredTokenFilter.class);
private Duration accessTokenExpiresSkew = Duration.ofMillis(1000);
private Clock clock = Clock.systemUTC();
#Autowired
private OAuth2AuthorizedClientService oAuth2AuthorizedClientService;
#Autowired
CustomOidcUserService userService;
private DefaultRefreshTokenTokenResponseClient accessTokenResponseClient;
private JwtDecoderFactory<ClientRegistration> jwtDecoderFactory;
private static final String INVALID_ID_TOKEN_ERROR_CODE = "invalid_id_token";
public ExpiredTokenFilter() {
super();
this.accessTokenResponseClient = new DefaultRefreshTokenTokenResponseClient();
this.jwtDecoderFactory = new OidcIdTokenDecoderFactory();
}
#Override
protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)
throws ServletException, IOException {
log.debug("my custom filter called ");
/**
* check if authentication is done.
*/
if (null != SecurityContextHolder.getContext().getAuthentication()) {
OAuth2AuthenticationToken currentUser = (OAuth2AuthenticationToken) SecurityContextHolder.getContext()
.getAuthentication();
OAuth2AuthorizedClient authorizedClient = this.oAuth2AuthorizedClientService
.loadAuthorizedClient(currentUser.getAuthorizedClientRegistrationId(), currentUser.getName());
/**
* Check if token existing token is expired.
*/
if (isExpired(authorizedClient.getAccessToken())) {
/*
* do something to get new access token
*/
log.debug(
"=========================== Token Expired !! going to refresh ================================================");
ClientRegistration clientRegistration = authorizedClient.getClientRegistration();
/*
* Call Auth server token endpoint to refresh token.
*/
OAuth2RefreshTokenGrantRequest refreshTokenGrantRequest = new OAuth2RefreshTokenGrantRequest(
clientRegistration, authorizedClient.getAccessToken(), authorizedClient.getRefreshToken());
OAuth2AccessTokenResponse accessTokenResponse = this.accessTokenResponseClient
.getTokenResponse(refreshTokenGrantRequest);
/*
* Convert id_token to OidcToken.
*/
OidcIdToken idToken = createOidcToken(clientRegistration, accessTokenResponse);
/*
* Since I have already implemented a custom OidcUserService, reuse existing
* code to get new user.
*/
OidcUser oidcUser = this.userService.loadUser(new OidcUserRequest(clientRegistration,
accessTokenResponse.getAccessToken(), idToken, accessTokenResponse.getAdditionalParameters()));
log.debug(
"=========================== Token Refresh Done !! ================================================");
/*
* Print old and new id_token, just in case.
*/
DefaultOidcUser user = (DefaultOidcUser) currentUser.getPrincipal();
log.debug("new id token is " + oidcUser.getIdToken().getTokenValue());
log.debug("old id token was " + user.getIdToken().getTokenValue());
/*
* Create new authentication(OAuth2AuthenticationToken).
*/
OAuth2AuthenticationToken updatedUser = new OAuth2AuthenticationToken(oidcUser,
oidcUser.getAuthorities(), currentUser.getAuthorizedClientRegistrationId());
/*
* Update access_token and refresh_token by saving new authorized client.
*/
OAuth2AuthorizedClient updatedAuthorizedClient = new OAuth2AuthorizedClient(clientRegistration,
currentUser.getName(), accessTokenResponse.getAccessToken(),
accessTokenResponse.getRefreshToken());
this.oAuth2AuthorizedClientService.saveAuthorizedClient(updatedAuthorizedClient, updatedUser);
/*
* Set new authentication in SecurityContextHolder.
*/
SecurityContextHolder.getContext().setAuthentication(updatedUser);
}
}
filterChain.doFilter(request, response);
}
private Boolean isExpired(OAuth2AccessToken oAuth2AccessToken) {
Instant now = this.clock.instant();
Instant expiresAt = oAuth2AccessToken.getExpiresAt();
return now.isAfter(expiresAt.minus(this.accessTokenExpiresSkew));
}
private OidcIdToken createOidcToken(ClientRegistration clientRegistration,
OAuth2AccessTokenResponse accessTokenResponse) {
JwtDecoder jwtDecoder = this.jwtDecoderFactory.createDecoder(clientRegistration);
Jwt jwt;
try {
jwt = jwtDecoder
.decode((String) accessTokenResponse.getAdditionalParameters().get(OidcParameterNames.ID_TOKEN));
} catch (JwtException ex) {
OAuth2Error invalidIdTokenError = new OAuth2Error(INVALID_ID_TOKEN_ERROR_CODE, ex.getMessage(), null);
throw new OAuth2AuthenticationException(invalidIdTokenError, invalidIdTokenError.toString(), ex);
}
OidcIdToken idToken = new OidcIdToken(jwt.getTokenValue(), jwt.getIssuedAt(), jwt.getExpiresAt(),
jwt.getClaims());
return idToken;
}
}
I am open for any suggestion to improve my code. Thanks.

Answer 1

There are not enough details to understand your use-case fully. It would be great to understand:
Spring security is rapidly evolving around OAuth2, consider mentioning the version you are using. My answer assumes 5.2+
Are you in servlet (user logged in somehow) or non-servlet (like #Scheduled method) environment
From the limited information and my limited knowledge I have following hints:
Consider using WebClient instead of RestTemplate, this is they way to go for the future. It is reactive but don't be scared. It can be used in "blocking" environment as well, you will not use it's full potential but you can still benefit from its better support for OAuth2
WebClient itself has a ServletOAuth2AuthorizedClientExchangeFilterFunction which does pretty much what you are trying to achieve
When creating ServletOAuth2AuthorizedClientExchangeFilterFunction you pass in AuthorizedClientServiceOAuth2AuthorizedClientManager which is a strategy on how to (re)authenticate client.
Sample configuration may look as follows:
#Bean
public WebClient webClient(ClientRegistrationRepository clientRegistrationRepository, OAuth2AuthorizedClientService authorizedClientService) {
AuthorizedClientServiceOAuth2AuthorizedClientManager manager = new AuthorizedClientServiceOAuth2AuthorizedClientManager(clientRegistrationRepository, authorizedClientService);
manager.setAuthorizedClientProvider(new DelegatingOAuth2AuthorizedClientProvider(
new RefreshTokenOAuth2AuthorizedClientProvider(),
new ClientCredentialsOAuth2AuthorizedClientProvider()));
ServletOAuth2AuthorizedClientExchangeFilterFunction oauth2 = new ServletOAuth2AuthorizedClientExchangeFilterFunction(manager);
oauth2.setDefaultClientRegistrationId("your-client-registratioin-id");
return WebClient.builder()
.filter(oauth2)
.apply(oauth2.oauth2Configuration())
.build();
}
And use it as:
#Autowire
private final WebClient webClient;
...
webClient.get()
.uri("http://localhost:8081/api/message")
.retrieve()
.bodyToMono(String.class)
.map(string -> "Retrieved using password grant: " + string)
.subscribe(log::info);
Hope this helps to move in the right direction! Have fun