/*
 * Copyright 2012-2020 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.boot.web.embedded.netty;

import java.net.Socket;
import java.net.URL;
import java.security.InvalidAlgorithmParameterException;
import java.security.KeyStore;
import java.security.KeyStoreException;
import java.security.NoSuchAlgorithmException;
import java.security.Principal;
import java.security.PrivateKey;
import java.security.UnrecoverableKeyException;
import java.security.cert.X509Certificate;
import java.util.Arrays;

import javax.net.ssl.KeyManager;
import javax.net.ssl.KeyManagerFactory;
import javax.net.ssl.KeyManagerFactorySpi;
import javax.net.ssl.ManagerFactoryParameters;
import javax.net.ssl.SSLEngine;
import javax.net.ssl.TrustManagerFactory;
import javax.net.ssl.X509ExtendedKeyManager;

import io.netty.handler.ssl.ClientAuth;
import io.netty.handler.ssl.SslContextBuilder;
import reactor.netty.http.server.HttpServer;
import reactor.netty.tcp.SslProvider;

import org.springframework.boot.web.server.Http2;
import org.springframework.boot.web.server.Ssl;
import org.springframework.boot.web.server.SslConfigurationValidator;
import org.springframework.boot.web.server.SslStoreProvider;
import org.springframework.boot.web.server.WebServerException;
import org.springframework.util.ResourceUtils;

NettyServerCustomizer that configures SSL for the given Reactor Netty server instance. 
Author:
Brian Clozel, Raheela Aslam, Chris Bono
Since:
2.0.0/**
 * {@link NettyServerCustomizer} that configures SSL for the given Reactor Netty server
 * instance.
 *
 * @author Brian Clozel
 * @author Raheela Aslam
 * @author Chris Bono
 * @since 2.0.0
 */
public class SslServerCustomizer implements NettyServerCustomizer {

	private final Ssl ssl;

	private final Http2 http2;

	private final SslStoreProvider sslStoreProvider;

	public SslServerCustomizer(Ssl ssl, Http2 http2, SslStoreProvider sslStoreProvider) {
		this.ssl = ssl;
		this.http2 = http2;
		this.sslStoreProvider = sslStoreProvider;
	}

	@Override
	public HttpServer apply(HttpServer server) {
		try {
			return server.secure((contextSpec) -> {
				SslProvider.DefaultConfigurationSpec spec = contextSpec.sslContext(getContextBuilder());
				if (this.http2 != null && this.http2.isEnabled()) {
					spec.defaultConfiguration(SslProvider.DefaultConfigurationType.H2);
				}
			});
		}
		catch (Exception ex) {
			throw new IllegalStateException(ex);
		}
	}

	protected SslContextBuilder getContextBuilder() {
		SslContextBuilder builder = SslContextBuilder.forServer(getKeyManagerFactory(this.ssl, this.sslStoreProvider))
				.trustManager(getTrustManagerFactory(this.ssl, this.sslStoreProvider));
		if (this.ssl.getEnabledProtocols() != null) {
			builder.protocols(this.ssl.getEnabledProtocols());
		}
		if (this.ssl.getCiphers() != null) {
			builder.ciphers(Arrays.asList(this.ssl.getCiphers()));
		}
		if (this.ssl.getClientAuth() == Ssl.ClientAuth.NEED) {
			builder.clientAuth(ClientAuth.REQUIRE);
		}
		else if (this.ssl.getClientAuth() == Ssl.ClientAuth.WANT) {
			builder.clientAuth(ClientAuth.OPTIONAL);
		}
		return builder;
	}

	protected KeyManagerFactory getKeyManagerFactory(Ssl ssl, SslStoreProvider sslStoreProvider) {
		try {
			KeyStore keyStore = getKeyStore(ssl, sslStoreProvider);
			SslConfigurationValidator.validateKeyAlias(keyStore, ssl.getKeyAlias());
			KeyManagerFactory keyManagerFactory = (ssl.getKeyAlias() == null)
					? KeyManagerFactory.getInstance(KeyManagerFactory.getDefaultAlgorithm())
					: new ConfigurableAliasKeyManagerFactory(ssl.getKeyAlias(),
							KeyManagerFactory.getDefaultAlgorithm());
			char[] keyPassword = (ssl.getKeyPassword() != null) ? ssl.getKeyPassword().toCharArray() : null;
			if (keyPassword == null && ssl.getKeyStorePassword() != null) {
				keyPassword = ssl.getKeyStorePassword().toCharArray();
			}
			keyManagerFactory.init(keyStore, keyPassword);
			return keyManagerFactory;
		}
		catch (Exception ex) {
			throw new IllegalStateException(ex);
		}
	}

	private KeyStore getKeyStore(Ssl ssl, SslStoreProvider sslStoreProvider) throws Exception {
		if (sslStoreProvider != null) {
			return sslStoreProvider.getKeyStore();
		}
		return loadKeyStore(ssl.getKeyStoreType(), ssl.getKeyStoreProvider(), ssl.getKeyStore(),
				ssl.getKeyStorePassword());
	}

	protected TrustManagerFactory getTrustManagerFactory(Ssl ssl, SslStoreProvider sslStoreProvider) {
		try {
			KeyStore store = getTrustStore(ssl, sslStoreProvider);
			TrustManagerFactory trustManagerFactory = TrustManagerFactory
					.getInstance(TrustManagerFactory.getDefaultAlgorithm());
			trustManagerFactory.init(store);
			return trustManagerFactory;
		}
		catch (Exception ex) {
			throw new IllegalStateException(ex);
		}
	}

	private KeyStore getTrustStore(Ssl ssl, SslStoreProvider sslStoreProvider) throws Exception {
		if (sslStoreProvider != null) {
			return sslStoreProvider.getTrustStore();
		}
		return loadTrustStore(ssl.getTrustStoreType(), ssl.getTrustStoreProvider(), ssl.getTrustStore(),
				ssl.getTrustStorePassword());
	}

	private KeyStore loadKeyStore(String type, String provider, String resource, String password) throws Exception {

		return loadStore(type, provider, resource, password);
	}

	private KeyStore loadTrustStore(String type, String provider, String resource, String password) throws Exception {
		if (resource == null) {
			return null;
		}
		return loadStore(type, provider, resource, password);
	}

	private KeyStore loadStore(String type, String provider, String resource, String password) throws Exception {
		type = (type != null) ? type : "JKS";
		KeyStore store = (provider != null) ? KeyStore.getInstance(type, provider) : KeyStore.getInstance(type);
		try {
			URL url = ResourceUtils.getURL(resource);
			store.load(url.openStream(), (password != null) ? password.toCharArray() : null);
			return store;
		}
		catch (Exception ex) {
			throw new WebServerException("Could not load key store '" + resource + "'", ex);
		}

	}

	
A KeyManagerFactory that allows a configurable key alias to be used. Due to the fact that the actual calls to retrieve the key by alias are done at request time the approach is to wrap the actual key managers with a ConfigurableAliasKeyManager. The actual SPI has to be wrapped as well due to the fact that KeyManagerFactory.getKeyManagers() is final. /**
	 * A {@link KeyManagerFactory} that allows a configurable key alias to be used. Due to
	 * the fact that the actual calls to retrieve the key by alias are done at request
	 * time the approach is to wrap the actual key managers with a
	 * {@link ConfigurableAliasKeyManager}. The actual SPI has to be wrapped as well due
	 * to the fact that {@link KeyManagerFactory#getKeyManagers()} is final.
	 */
	private static final class ConfigurableAliasKeyManagerFactory extends KeyManagerFactory {

		private ConfigurableAliasKeyManagerFactory(String alias, String algorithm) throws NoSuchAlgorithmException {
			this(KeyManagerFactory.getInstance(algorithm), alias, algorithm);
		}

		private ConfigurableAliasKeyManagerFactory(KeyManagerFactory delegate, String alias, String algorithm) {
			super(new ConfigurableAliasKeyManagerFactorySpi(delegate, alias), delegate.getProvider(), algorithm);
		}

	}

	private static final class ConfigurableAliasKeyManagerFactorySpi extends KeyManagerFactorySpi {

		private final KeyManagerFactory delegate;

		private final String alias;

		private ConfigurableAliasKeyManagerFactorySpi(KeyManagerFactory delegate, String alias) {
			this.delegate = delegate;
			this.alias = alias;
		}

		@Override
		protected void engineInit(KeyStore keyStore, char[] chars)
				throws KeyStoreException, NoSuchAlgorithmException, UnrecoverableKeyException {
			this.delegate.init(keyStore, chars);
		}

		@Override
		protected void engineInit(ManagerFactoryParameters managerFactoryParameters)
				throws InvalidAlgorithmParameterException {
			throw new InvalidAlgorithmParameterException("Unsupported ManagerFactoryParameters");
		}

		@Override
		protected KeyManager[] engineGetKeyManagers() {
			return Arrays.stream(this.delegate.getKeyManagers()).filter(X509ExtendedKeyManager.class::isInstance)
					.map(X509ExtendedKeyManager.class::cast).map(this::wrap).toArray(KeyManager[]::new);
		}

		private ConfigurableAliasKeyManager wrap(X509ExtendedKeyManager keyManager) {
			return new ConfigurableAliasKeyManager(keyManager, this.alias);
		}

	}

	private static final class ConfigurableAliasKeyManager extends X509ExtendedKeyManager {

		private final X509ExtendedKeyManager delegate;

		private final String alias;

		private ConfigurableAliasKeyManager(X509ExtendedKeyManager keyManager, String alias) {
			this.delegate = keyManager;
			this.alias = alias;
		}

		@Override
		public String chooseEngineClientAlias(String[] strings, Principal[] principals, SSLEngine sslEngine) {
			return this.delegate.chooseEngineClientAlias(strings, principals, sslEngine);
		}

		@Override
		public String chooseEngineServerAlias(String s, Principal[] principals, SSLEngine sslEngine) {
			return (this.alias != null) ? this.alias : this.delegate.chooseEngineServerAlias(s, principals, sslEngine);
		}

		@Override
		public String chooseClientAlias(String[] keyType, Principal[] issuers, Socket socket) {
			return this.delegate.chooseClientAlias(keyType, issuers, socket);
		}

		@Override
		public String chooseServerAlias(String keyType, Principal[] issuers, Socket socket) {
			return this.delegate.chooseServerAlias(keyType, issuers, socket);
		}

		@Override
		public X509Certificate[] getCertificateChain(String alias) {
			return this.delegate.getCertificateChain(alias);
		}

		@Override
		public String[] getClientAliases(String keyType, Principal[] issuers) {
			return this.delegate.getClientAliases(keyType, issuers);
		}

		@Override
		public PrivateKey getPrivateKey(String alias) {
			return this.delegate.getPrivateKey(alias);
		}

		@Override
		public String[] getServerAliases(String keyType, Principal[] issuers) {
			return this.delegate.getServerAliases(keyType, issuers);
		}

	}

}