spring-authorization-server/core/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 java.time.Instant;
import java.time.temporal.ChronoUnit;
import java.util.Base64;
import java.util.Set;

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;

/**
 * An {@link AuthenticationProvider} implementation for the OAuth 2.0 Client Credentials Grant.
 *
 * @author Alexey Nesterov
 * @since 0.0.1
 * @see OAuth2ClientCredentialsAuthenticationToken
 * @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 StringKeyGenerator accessTokenGenerator = new Base64StringKeyGenerator(Base64.getUrlEncoder());

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

		OAuth2ClientAuthenticationToken clientPrincipal = null;
		if (OAuth2ClientAuthenticationToken.class.isAssignableFrom(clientCredentialsAuthenticationToken.getPrincipal().getClass())) {
			clientPrincipal = (OAuth2ClientAuthenticationToken) clientCredentialsAuthenticationToken.getPrincipal();
		}

		if (clientPrincipal == null || !clientPrincipal.isAuthenticated()) {
			throw new OAuth2AuthenticationException(new OAuth2Error(OAuth2ErrorCodes.INVALID_CLIENT));
		}

		Set<String> clientScopes = clientPrincipal.getRegisteredClient().getScopes();
		Set<String> requestedScopes = clientCredentialsAuthenticationToken.getScopes();
		if (!clientScopes.containsAll(requestedScopes)) {
			throw new OAuth2AuthenticationException(new OAuth2Error(OAuth2ErrorCodes.INVALID_SCOPE));
		}

		if (requestedScopes == null || requestedScopes.isEmpty()) {
			requestedScopes = clientScopes;
		}

		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, requestedScopes);

		return new OAuth2AccessTokenAuthenticationToken(
				clientPrincipal.getRegisteredClient(), clientPrincipal, accessToken);
	}

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