How to get google user email to whitelist users when authenticating using Spring Boot OAuth2 against Google

Question

I want to whitelist users connecting to my OAuth2 client, and I can't figure out how to get the user name (specifically the Google email address).

I created a Spring Boot OAuth2 application based on a Spring Tutorial

https://spring.io/guides/tutorials/spring-boot-oauth2/#_social_login_manual

I'm authenticating against Google (successfully). I want to determine the user email address so I can whitelist authenticating users.

This website,

http://www.baeldung.com/spring-security-openid-connect#filter

suggests that I can unpack the "id_token" I get back from Google, something like this:

/**
 * logic to unpack a ConnectID id_token like what we get from Google -
 * see "Spring Security and OpenID Connect" - heading '4. Custom OpenID Connect Filter':
 *         http://www.baeldung.com/spring-security-openid-connect#filter
 * 
 * @param oa2token
 * @return
 */
private static UsernamePasswordAuthenticationToken getOpenIDDataForToken(OAuth2AccessToken oa2token)
{
        try {
            String idToken = oa2token.getAdditionalInformation().get("id_token").toString();
            Jwt tokenDecoded = JwtHelper.decode(idToken);
            Map<String, String> authInfo = new ObjectMapper().readValue(tokenDecoded.getClaims(), Map.class);

            OpenIdConnectUserDetails user = new OpenIdConnectUserDetails(authInfo, oa2token);
            return new UsernamePasswordAuthenticationToken(user, null, user.getAuthorities());
        } catch (InvalidTokenException e) {
            throw new BadCredentialsException("Could not obtain user details from token", e);
        }
}

but I can't get this code to compile - I can't figure out how to get class JtwHelper!

I searched around and the following might be the right Maven dependency:

        <!-- https://mvnrepository.com/artifact/org.springframework.security/spring-security-jwt -->
        <dependency>
            <groupId>org.springframework.security</groupId>
            <artifactId>spring-security-jwt</artifactId>
        </dependency>

but adding this to my pom.xml doesn't help - I don't get a real Jar file back in my .m2 repository - I get a text file!!! and bottom line, Eclipse doesn't resolve the type JwtHelper.

Help? I'm not sure where I've gone wrong.

Answer 1

Looks like an answer on this SO page had my answer (thanks @user2802927):

How to get custom user info from OAuth2 authorization server /user endpoint

Here's the code:

    Principal principal = servlet_request.getUserPrincipal();
    try {
         if (principal != null) {
                OAuth2Authentication oAuth2Authentication = (OAuth2Authentication) principal;
                Authentication authentication = oAuth2Authentication.getUserAuthentication();
                Map<String, String> details = new LinkedHashMap<>();
                details = (Map<String, String>) authentication.getDetails();
                Map<String, String> map = new LinkedHashMap<>();
                map.put("email", details.get("email"));
                logger.debug("details map is: {}", map);
            }
    } catch (Exception e) {
        logger.error("dumping principal " + principal + "failed, exception: ", e );
    }

The output showed that I found success - the user's email address!!!

2017-05-23 11:48:26.751 DEBUG 7687 --- [nio-8443-exec-1] ication$$EnhancerBySpringCGLIB$$91415b85 :
details map is: {email=myemailaddress@gmail.com}