Simplify customizing the access token response

[Hccake]

In OAuth2.1 draft，Token Response can be added with additional parameters.

It can currently be solved by replacing the default AuthenticationSuccessHandler.

Hope there is a component that can be easily implemented, like TokenEnhancer in spring-security-oauth2.

[javamachr]

There is org.springframework.security.oauth2.server.authorization.token.OAuth2TokenCustomizer example here

[Hccake]

There is org.springframework.security.oauth2.server.authorization.token.OAuth2TokenCustomizer example here

I think token endpoint response additional parameters and token claims are different things, and by default token claims are not in the response.

For example, the idToken attribute of OIDC is officially stored in additionalParameters:
see OAuth2AuthorizationCodeAuthenticationProvider line 179 - 213

		// ----- ID token -----
		OidcIdToken idToken;
		if (authorizationRequest.getScopes().contains(OidcScopes.OPENID)) {
			// @formatter:off
			tokenContext = tokenContextBuilder
					.tokenType(ID_TOKEN_TOKEN_TYPE)
					.authorization(authorizationBuilder.build())	// ID token customizer may need access to the access token and/or refresh token
					.build();
			// @formatter:on
			OAuth2Token generatedIdToken = this.tokenGenerator.generate(tokenContext);
			if (!(generatedIdToken instanceof Jwt)) {
				OAuth2Error error = new OAuth2Error(OAuth2ErrorCodes.SERVER_ERROR,
						"The token generator failed to generate the ID token.", ERROR_URI);
				throw new OAuth2AuthenticationException(error);
			}
			idToken = new OidcIdToken(generatedIdToken.getTokenValue(), generatedIdToken.getIssuedAt(),
					generatedIdToken.getExpiresAt(), ((Jwt) generatedIdToken).getClaims());
			authorizationBuilder.token(idToken, (metadata) ->
					metadata.put(OAuth2Authorization.Token.CLAIMS_METADATA_NAME, idToken.getClaims()));
		} else {
			idToken = null;
		}

		authorization = authorizationBuilder.build();

		// Invalidate the authorization code as it can only be used once
		authorization = OAuth2AuthenticationProviderUtils.invalidate(authorization, authorizationCode.getToken());

		this.authorizationService.save(authorization);

		Map<String, Object> additionalParameters = Collections.emptyMap();
		if (idToken != null) {
			additionalParameters = new HashMap<>();
			additionalParameters.put(OidcParameterNames.ID_TOKEN, idToken.getTokenValue());
		}

[jgrandja]

@Hccake As mentioned by @javamachr, the OAuth2TokenCustomizer is the equivalent to TokenEnhancer in spring-security-oauth2.

authorizationServerConfigurer.tokenEndpoint.accessTokenResponseHandler() provides the ability to customize the OAuth 2.0 Access Token Response parameters, however, the parameters are not necessarily the same as the claims contained in the access token.

Can you be more specific on what type of parameters you want to customize (add?) to the OAuth 2.0 Access Token Response?

[Hccake]

For some clients, when returning access_token, want to directly return some user information, such as user_id.

When using spring-security-oauth2, it is possible to do this with TokenEnhancer, but not with OAuth2TokenCustomizer in spring-authorization-server.

Using JWT type tokens can extend claims through OAuth2TokenCustomizer, but some old systems use Opaque type tokens, and the claims extended by OAuth2TokenCustomizer cannot be obtained in the response.

[jgrandja]

@Hccake

but some old systems use Opaque type tokens, and the claims extended by OAuth2TokenCustomizer cannot be obtained in the response.

As per the reference documentation for OAuth2TokenCustomizer<OAuth2TokenClaimsContext>:

An OAuth2TokenCustomizer declared with a generic type of OAuth2TokenClaimsContext (implements OAuth2TokenContext) provides the ability to customize the claims of an "opaque" OAuth2AccessToken.

You can register a OAuth2TokenCustomizer<OAuth2TokenClaimsContext> @Bean that adds user information as claims.

The client can obtain the user information claims from the OAuth2 Token Introspection Endpoint on a subsequent call.

If you need the user information returned in the access token response, then you can supply a custom AuthenticationSuccessHandler to OAuth2TokenEndpointFilter. The following implementation is similar to the default OAuth2TokenEndpointFilter.sendAccessTokenResponse() but it can also add claims from the opaque token.

public static class CustomAccessTokenResponseHandler implements AuthenticationSuccessHandler {
	private final HttpMessageConverter<OAuth2AccessTokenResponse> accessTokenHttpResponseConverter =
			new OAuth2AccessTokenResponseHttpMessageConverter();
	private OAuth2AuthorizationService authorizationService;

	public CustomAccessTokenResponseHandler(OAuth2AuthorizationService authorizationService) {
		this.authorizationService = authorizationService;
	}

	@Override
	public void onAuthenticationSuccess(HttpServletRequest request, HttpServletResponse response, Authentication authentication) throws IOException, ServletException {
		OAuth2AccessTokenAuthenticationToken accessTokenAuthentication =
				(OAuth2AccessTokenAuthenticationToken) authentication;

		OAuth2AccessToken accessToken = accessTokenAuthentication.getAccessToken();
		OAuth2RefreshToken refreshToken = accessTokenAuthentication.getRefreshToken();
		Map<String, Object> additionalParameters = accessTokenAuthentication.getAdditionalParameters();

		// Lookup the authorization using the access token
		OAuth2Authorization authorization = this.authorizationService.findByToken(
				accessToken.getTokenValue(), OAuth2TokenType.ACCESS_TOKEN);

		Map<String, Object> opaqueTokenClaims = authorization.getAccessToken().getClaims();
		Authentication userPrincipal = authorization.getAttribute(Principal.class.getName());

		OAuth2AccessTokenResponse.Builder builder =
				OAuth2AccessTokenResponse.withToken(accessToken.getTokenValue())
						.tokenType(accessToken.getTokenType())
						.scopes(accessToken.getScopes());
		if (accessToken.getIssuedAt() != null && accessToken.getExpiresAt() != null) {
			builder.expiresIn(ChronoUnit.SECONDS.between(accessToken.getIssuedAt(), accessToken.getExpiresAt()));
		}
		if (refreshToken != null) {
			builder.refreshToken(refreshToken.getTokenValue());
		}
		if (!CollectionUtils.isEmpty(additionalParameters)) {
			builder.additionalParameters(additionalParameters);
		}

		// TODO Add custom response parameters using `opaqueTokenClaims` and/or `userPrincipal`


		OAuth2AccessTokenResponse accessTokenResponse = builder.build();
		ServletServerHttpResponse httpResponse = new ServletServerHttpResponse(response);
		this.accessTokenHttpResponseConverter.write(accessTokenResponse, null, httpResponse);
	}

}

I'll close this as either solution provided will work.