spring-authorization-server/oauth2-authorization-server/src/main/java/org/springframework/security/oauth2/server/authorization/authentication/OAuth2ClientCredentialsAuthenticationProvider.java

/*
 * Copyright 2020 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.springframework.security.oauth2.server.authorization.authentication;

import org.springframework.security.authentication.AuthenticationProvider;
import org.springframework.security.core.Authentication;
import org.springframework.security.core.AuthenticationException;
import org.springframework.security.crypto.keygen.Base64StringKeyGenerator;
import org.springframework.security.crypto.keygen.StringKeyGenerator;
import org.springframework.security.oauth2.core.OAuth2AccessToken;
import org.springframework.security.oauth2.core.OAuth2AuthenticationException;
import org.springframework.security.oauth2.core.OAuth2Error;
import org.springframework.security.oauth2.core.OAuth2ErrorCodes;
import org.springframework.security.oauth2.server.authorization.OAuth2Authorization;
import org.springframework.security.oauth2.server.authorization.OAuth2AuthorizationService;
import org.springframework.security.oauth2.server.authorization.client.RegisteredClient;
import org.springframework.util.Assert;
import org.springframework.util.CollectionUtils;

import java.time.Instant;
import java.time.temporal.ChronoUnit;
import java.util.Base64;
import java.util.LinkedHashSet;
import java.util.Set;
import java.util.stream.Collectors;

/**
 * An {@link AuthenticationProvider} implementation for the OAuth 2.0 Client Credentials Grant.
 *
 * @author Alexey Nesterov
 * @since 0.0.1
 * @see OAuth2ClientCredentialsAuthenticationToken
 * @see OAuth2AccessTokenAuthenticationToken
 * @see OAuth2AuthorizationService
 * @see <a target="_blank" href="https://tools.ietf.org/html/rfc6749#section-4.4">Section 4.4 Client Credentials Grant</a>
 * @see <a target="_blank" href="https://tools.ietf.org/html/rfc6749#section-4.4.2">Section 4.4.2 Access Token Request</a>
 */
public class OAuth2ClientCredentialsAuthenticationProvider implements AuthenticationProvider {
	private final OAuth2AuthorizationService authorizationService;
	private final StringKeyGenerator accessTokenGenerator = new Base64StringKeyGenerator(Base64.getUrlEncoder());

	/**
	 * Constructs an {@code OAuth2ClientCredentialsAuthenticationProvider} using the provided parameters.
	 *
	 * @param authorizationService the authorization service
	 */
	public OAuth2ClientCredentialsAuthenticationProvider(OAuth2AuthorizationService authorizationService) {
		Assert.notNull(authorizationService, "authorizationService cannot be null");
		this.authorizationService = authorizationService;
	}

	@Override
	public Authentication authenticate(Authentication authentication) throws AuthenticationException {
		OAuth2ClientCredentialsAuthenticationToken clientCredentialsAuthentication =
				(OAuth2ClientCredentialsAuthenticationToken) authentication;

		OAuth2ClientAuthenticationToken clientPrincipal = null;
		if (OAuth2ClientAuthenticationToken.class.isAssignableFrom(clientCredentialsAuthentication.getPrincipal().getClass())) {
			clientPrincipal = (OAuth2ClientAuthenticationToken) clientCredentialsAuthentication.getPrincipal();
		}
		if (clientPrincipal == null || !clientPrincipal.isAuthenticated()) {
			throw new OAuth2AuthenticationException(new OAuth2Error(OAuth2ErrorCodes.INVALID_CLIENT));
		}
		RegisteredClient registeredClient = clientPrincipal.getRegisteredClient();

		Set<String> scopes = registeredClient.getScopes();		// Default to configured scopes
		if (!CollectionUtils.isEmpty(clientCredentialsAuthentication.getScopes())) {
			Set<String> unauthorizedScopes = clientCredentialsAuthentication.getScopes().stream()
					.filter(requestedScope -> !registeredClient.getScopes().contains(requestedScope))
					.collect(Collectors.toSet());
			if (!CollectionUtils.isEmpty(unauthorizedScopes)) {
				throw new OAuth2AuthenticationException(new OAuth2Error(OAuth2ErrorCodes.INVALID_SCOPE));
			}
			scopes = new LinkedHashSet<>(clientCredentialsAuthentication.getScopes());
		}

		String tokenValue = this.accessTokenGenerator.generateKey();
		Instant issuedAt = Instant.now();
		Instant expiresAt = issuedAt.plus(1, ChronoUnit.HOURS);		// TODO Allow configuration for access token lifespan
		OAuth2AccessToken accessToken = new OAuth2AccessToken(OAuth2AccessToken.TokenType.BEARER,
				tokenValue, issuedAt, expiresAt, scopes);

		OAuth2Authorization authorization = OAuth2Authorization.withRegisteredClient(registeredClient)
				.principalName(clientPrincipal.getName())
				.accessToken(accessToken)
				.build();
		this.authorizationService.save(authorization);

		return new OAuth2AccessTokenAuthenticationToken(registeredClient, clientPrincipal, accessToken);
	}

	@Override
	public boolean supports(Class<?> authentication) {
		return OAuth2ClientCredentialsAuthenticationToken.class.isAssignableFrom(authentication);
	}
}