org.springframework.boot.actuate.autoconfigure.cloudfoundry.reactive.ReactiveTokenValidator.java Source code

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Here is the source code for org.springframework.boot.actuate.autoconfigure.cloudfoundry.reactive.ReactiveTokenValidator.java

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/*
 * Copyright 2012-2019 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.boot.actuate.autoconfigure.cloudfoundry.reactive;

import java.security.GeneralSecurityException;
import java.security.KeyFactory;
import java.security.NoSuchAlgorithmException;
import java.security.PublicKey;
import java.security.Signature;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.X509EncodedKeySpec;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.TimeUnit;

import reactor.core.publisher.Mono;

import org.springframework.boot.actuate.autoconfigure.cloudfoundry.CloudFoundryAuthorizationException;
import org.springframework.boot.actuate.autoconfigure.cloudfoundry.CloudFoundryAuthorizationException.Reason;
import org.springframework.boot.actuate.autoconfigure.cloudfoundry.Token;
import org.springframework.util.Base64Utils;

/**
 * Validator used to ensure that a signed {@link Token} has not been tampered with.
 *
 * @author Madhura Bhave
 */
class ReactiveTokenValidator {

    private final ReactiveCloudFoundrySecurityService securityService;

    private volatile ConcurrentMap<String, String> cachedTokenKeys = new ConcurrentHashMap<>();

    ReactiveTokenValidator(ReactiveCloudFoundrySecurityService securityService) {
        this.securityService = securityService;
    }

    Mono<Void> validate(Token token) {
        return validateAlgorithm(token).then(validateKeyIdAndSignature(token)).then(validateExpiry(token))
                .then(validateIssuer(token)).then(validateAudience(token));
    }

    private Mono<Void> validateAlgorithm(Token token) {
        String algorithm = token.getSignatureAlgorithm();
        if (algorithm == null) {
            return Mono.error(new CloudFoundryAuthorizationException(Reason.INVALID_SIGNATURE,
                    "Signing algorithm cannot be null"));
        }
        if (!algorithm.equals("RS256")) {
            return Mono.error(new CloudFoundryAuthorizationException(Reason.UNSUPPORTED_TOKEN_SIGNING_ALGORITHM,
                    "Signing algorithm " + algorithm + " not supported"));
        }
        return Mono.empty();
    }

    private Mono<Void> validateKeyIdAndSignature(Token token) {
        return getTokenKey(token).filter((tokenKey) -> hasValidSignature(token, tokenKey))
                .switchIfEmpty(Mono.error(new CloudFoundryAuthorizationException(Reason.INVALID_SIGNATURE,
                        "RSA Signature did not match content")))
                .then();
    }

    private Mono<String> getTokenKey(Token token) {
        String keyId = token.getKeyId();
        String cached = this.cachedTokenKeys.get(keyId);
        if (cached != null) {
            return Mono.just(cached);
        }
        return this.securityService.fetchTokenKeys().doOnSuccess(this::cacheTokenKeys)
                .filter((tokenKeys) -> tokenKeys.containsKey(keyId)).map((tokenKeys) -> tokenKeys.get(keyId))
                .switchIfEmpty(Mono.error(new CloudFoundryAuthorizationException(Reason.INVALID_KEY_ID,
                        "Key Id present in token header does not match")));
    }

    private void cacheTokenKeys(Map<String, String> tokenKeys) {
        this.cachedTokenKeys = new ConcurrentHashMap<>(tokenKeys);
    }

    private boolean hasValidSignature(Token token, String key) {
        try {
            PublicKey publicKey = getPublicKey(key);
            Signature signature = Signature.getInstance("SHA256withRSA");
            signature.initVerify(publicKey);
            signature.update(token.getContent());
            return signature.verify(token.getSignature());
        } catch (GeneralSecurityException ex) {
            return false;
        }
    }

    private PublicKey getPublicKey(String key) throws NoSuchAlgorithmException, InvalidKeySpecException {
        key = key.replace("-----BEGIN PUBLIC KEY-----\n", "");
        key = key.replace("-----END PUBLIC KEY-----", "");
        key = key.trim().replace("\n", "");
        byte[] bytes = Base64Utils.decodeFromString(key);
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(bytes);
        return KeyFactory.getInstance("RSA").generatePublic(keySpec);
    }

    private Mono<Void> validateExpiry(Token token) {
        long currentTime = TimeUnit.MILLISECONDS.toSeconds(System.currentTimeMillis());
        if (currentTime > token.getExpiry()) {
            return Mono.error(new CloudFoundryAuthorizationException(Reason.TOKEN_EXPIRED, "Token expired"));
        }
        return Mono.empty();
    }

    private Mono<Void> validateIssuer(Token token) {
        return this.securityService.getUaaUrl().map((uaaUrl) -> String.format("%s/oauth/token", uaaUrl))
                .filter((issuerUri) -> issuerUri.equals(token.getIssuer()))
                .switchIfEmpty(Mono.error(new CloudFoundryAuthorizationException(Reason.INVALID_ISSUER,
                        "Token issuer does not match")))
                .then();
    }

    private Mono<Void> validateAudience(Token token) {
        if (!token.getScope().contains("actuator.read")) {
            return Mono.error(new CloudFoundryAuthorizationException(Reason.INVALID_AUDIENCE,
                    "Token does not have audience actuator"));
        }
        return Mono.empty();
    }

}