/*
    * Copyright 2016 The Netty Project
    *
    * The Netty Project licenses this file to you 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 io.netty5.handler.ssl;
  
  import io.netty.internal.tcnative.CertificateCallback;
  import io.netty.internal.tcnative.SSL;
  import io.netty.internal.tcnative.SSLContext;
  import io.netty5.util.internal.EmptyArrays;
  
  import javax.net.ssl.KeyManagerFactory;
  import javax.net.ssl.SSLException;
  import javax.net.ssl.TrustManagerFactory;
  import javax.net.ssl.X509ExtendedTrustManager;
  import javax.net.ssl.X509TrustManager;
  import javax.security.auth.x500.X500Principal;
  import java.security.KeyStore;
  import java.security.PrivateKey;
  import java.security.cert.X509Certificate;
  import java.util.Arrays;
  import java.util.Collections;
  import java.util.HashSet;
  import java.util.LinkedHashSet;
  import java.util.Map;
  import java.util.Set;
  
  /**
   * A client-side {@link SslContext} which uses OpenSSL's SSL/TLS implementation.
   * <p>Instances of this class must be {@link #release() released} or else native memory will leak!
   *
   * <p>Instances of this class <strong>must not</strong> be released before any {@link ReferenceCountedOpenSslEngine}
   * which depends upon the instance of this class is released. Otherwise if any method of
   * {@link ReferenceCountedOpenSslEngine} is called which uses this class's JNI resources the JVM may crash.
   */
  public final class ReferenceCountedOpenSslClientContext extends ReferenceCountedOpenSslContext {
  
      private static final Set<String> SUPPORTED_KEY_TYPES = Collections.unmodifiableSet(new LinkedHashSet<>(
              Arrays.asList(OpenSslKeyMaterialManager.KEY_TYPE_RSA,
                            OpenSslKeyMaterialManager.KEY_TYPE_DH_RSA,
                            OpenSslKeyMaterialManager.KEY_TYPE_EC,
                            OpenSslKeyMaterialManager.KEY_TYPE_EC_RSA,
                            OpenSslKeyMaterialManager.KEY_TYPE_EC_EC)));
  
      private final OpenSslSessionContext sessionContext;
  
      ReferenceCountedOpenSslClientContext(X509Certificate[] trustCertCollection, TrustManagerFactory trustManagerFactory,
                                           X509Certificate[] keyCertChain, PrivateKey key, String keyPassword,
                                           KeyManagerFactory keyManagerFactory, Iterable<String> ciphers,
                                           CipherSuiteFilter cipherFilter, ApplicationProtocolConfig apn,
                                           String[] protocols, long sessionCacheSize, long sessionTimeout,
                                           boolean enableOcsp, String keyStore,
                                           Map.Entry<SslContextOption<?>, Object>... options) throws SSLException {
          super(ciphers, cipherFilter, toNegotiator(apn), SSL.SSL_MODE_CLIENT, keyCertChain,
                ClientAuth.NONE, protocols, false, enableOcsp, true, options);
          boolean success = false;
          try {
              sessionContext = newSessionContext(this, ctx, engineMap, trustCertCollection, trustManagerFactory,
                                                 keyCertChain, key, keyPassword, keyManagerFactory, keyStore,
                                                 sessionCacheSize, sessionTimeout);
              success = true;
          } finally {
              if (!success) {
                  release();
              }
          }
      }
  
      @Override
      public OpenSslSessionContext sessionContext() {
          return sessionContext;
      }
  
      static OpenSslSessionContext newSessionContext(ReferenceCountedOpenSslContext thiz, long ctx,
                                                     OpenSslEngineMap engineMap,
                                                     X509Certificate[] trustCertCollection,
                                                     TrustManagerFactory trustManagerFactory,
                                                     X509Certificate[] keyCertChain, PrivateKey key,
                                                     String keyPassword, KeyManagerFactory keyManagerFactory,
                                                     String keyStore, long sessionCacheSize, long sessionTimeout)
              throws SSLException {
          if (key == null && keyCertChain != null || key != null && keyCertChain == null) {
              throw new IllegalArgumentException(
                      "Either both keyCertChain and key needs to be null or none of them");
          }
          OpenSslKeyMaterialProvider keyMaterialProvider = null;
          try {
              try {
                 if (!OpenSsl.supportsKeyManagerFactory()) {
                     if (keyManagerFactory != null) {
                         throw new IllegalArgumentException(
                                 "KeyManagerFactory not supported");
                     }
                     if (keyCertChain != null/* && key != null*/) {
                         setKeyMaterial(ctx, keyCertChain, key, keyPassword);
                     }
                 } else {
                     // javadocs state that keyManagerFactory has precedent over keyCertChain
                     if (keyManagerFactory == null && keyCertChain != null) {
                         char[] keyPasswordChars = keyStorePassword(keyPassword);
                         KeyStore ks = buildKeyStore(keyCertChain, key, keyPasswordChars, keyStore);
                         if (ks.aliases().hasMoreElements()) {
                             keyManagerFactory = new OpenSslX509KeyManagerFactory();
                         } else {
                             keyManagerFactory = new OpenSslCachingX509KeyManagerFactory(
                                     KeyManagerFactory.getInstance(KeyManagerFactory.getDefaultAlgorithm()));
                         }
                         keyManagerFactory.init(ks, keyPasswordChars);
                         keyMaterialProvider = providerFor(keyManagerFactory, keyPassword);
                     } else if (keyManagerFactory != null) {
                         keyMaterialProvider = providerFor(keyManagerFactory, keyPassword);
                     }
 
                     if (keyMaterialProvider != null) {
                         OpenSslKeyMaterialManager materialManager = new OpenSslKeyMaterialManager(keyMaterialProvider);
                         SSLContext.setCertificateCallback(ctx, new OpenSslClientCertificateCallback(
                                 engineMap, materialManager));
                     }
                 }
             } catch (Exception e) {
                 throw new SSLException("failed to set certificate and key", e);
             }
 
             // On the client side we always need to use SSL_CVERIFY_OPTIONAL (which will translate to SSL_VERIFY_PEER)
             // to ensure that when the TrustManager throws we will produce the correct alert back to the server.
             //
             // See:
             //   - https://www.openssl.org/docs/man1.0.2/man3/SSL_CTX_set_verify.html
             //   - https://github.com/netty/netty/issues/8942
             SSLContext.setVerify(ctx, SSL.SSL_CVERIFY_OPTIONAL, VERIFY_DEPTH);
 
             try {
                 if (trustCertCollection != null) {
                     trustManagerFactory = buildTrustManagerFactory(trustCertCollection, trustManagerFactory, keyStore);
                 } else if (trustManagerFactory == null) {
                     trustManagerFactory = TrustManagerFactory.getInstance(
                             TrustManagerFactory.getDefaultAlgorithm());
                     trustManagerFactory.init((KeyStore) null);
                 }
                 final X509TrustManager manager = chooseTrustManager(trustManagerFactory.getTrustManagers());
 
                 // IMPORTANT: The callbacks set for verification must be static to prevent memory leak as
                 //            otherwise the context can never be collected. This is because the JNI code holds
                 //            a global reference to the callbacks.
                 //
                 //            See https://github.com/netty/netty/issues/5372
 
                 // Use this to prevent an error when running on java < 7
                 if (useExtendedTrustManager(manager)) {
                     SSLContext.setCertVerifyCallback(ctx,
                             new ExtendedTrustManagerVerifyCallback(engineMap, (X509ExtendedTrustManager) manager));
                 } else {
                     SSLContext.setCertVerifyCallback(ctx, new TrustManagerVerifyCallback(engineMap, manager));
                 }
             } catch (Exception e) {
                 if (keyMaterialProvider != null) {
                     keyMaterialProvider.destroy();
                 }
                 throw new SSLException("unable to setup trustmanager", e);
             }
             OpenSslClientSessionContext context = new OpenSslClientSessionContext(thiz, keyMaterialProvider);
             context.setSessionCacheEnabled(CLIENT_ENABLE_SESSION_CACHE);
             if (sessionCacheSize > 0) {
                 context.setSessionCacheSize((int) Math.min(sessionCacheSize, Integer.MAX_VALUE));
             }
             if (sessionTimeout > 0) {
                 context.setSessionTimeout((int) Math.min(sessionTimeout, Integer.MAX_VALUE));
             }
 
             if (CLIENT_ENABLE_SESSION_TICKET) {
                 context.setTicketKeys();
             }
 
             keyMaterialProvider = null;
             return context;
         } finally {
             if (keyMaterialProvider != null) {
                 keyMaterialProvider.destroy();
             }
         }
     }
 
     static final class OpenSslClientSessionContext extends OpenSslSessionContext {
         OpenSslClientSessionContext(ReferenceCountedOpenSslContext context, OpenSslKeyMaterialProvider provider) {
             super(context, provider, SSL.SSL_SESS_CACHE_CLIENT, new OpenSslClientSessionCache(context.engineMap));
         }
     }
 
     private static final class TrustManagerVerifyCallback extends AbstractCertificateVerifier {
         private final X509TrustManager manager;
 
         TrustManagerVerifyCallback(OpenSslEngineMap engineMap, X509TrustManager manager) {
             super(engineMap);
             this.manager = manager;
         }
 
         @Override
         void verify(ReferenceCountedOpenSslEngine engine, X509Certificate[] peerCerts, String auth)
                 throws Exception {
             manager.checkServerTrusted(peerCerts, auth);
         }
     }
 
     private static final class ExtendedTrustManagerVerifyCallback extends AbstractCertificateVerifier {
         private final X509ExtendedTrustManager manager;
 
         ExtendedTrustManagerVerifyCallback(OpenSslEngineMap engineMap, X509ExtendedTrustManager manager) {
             super(engineMap);
             this.manager = manager;
         }
 
         @Override
         void verify(ReferenceCountedOpenSslEngine engine, X509Certificate[] peerCerts, String auth)
                 throws Exception {
             manager.checkServerTrusted(peerCerts, auth, engine);
         }
     }
 
     private static final class OpenSslClientCertificateCallback implements CertificateCallback {
         private final OpenSslEngineMap engineMap;
         private final OpenSslKeyMaterialManager keyManagerHolder;
 
         OpenSslClientCertificateCallback(OpenSslEngineMap engineMap, OpenSslKeyMaterialManager keyManagerHolder) {
             this.engineMap = engineMap;
             this.keyManagerHolder = keyManagerHolder;
         }
 
         @Override
         public void handle(long ssl, byte[] keyTypeBytes, byte[][] asn1DerEncodedPrincipals) throws Exception {
             final ReferenceCountedOpenSslEngine engine = engineMap.get(ssl);
             // May be null if it was destroyed in the meantime.
             if (engine == null) {
                 return;
             }
             try {
                 final Set<String> keyTypesSet = supportedClientKeyTypes(keyTypeBytes);
                 final String[] keyTypes = keyTypesSet.toArray(EmptyArrays.EMPTY_STRINGS);
                 final X500Principal[] issuers;
                 if (asn1DerEncodedPrincipals == null) {
                     issuers = null;
                 } else {
                     issuers = new X500Principal[asn1DerEncodedPrincipals.length];
                     for (int i = 0; i < asn1DerEncodedPrincipals.length; i++) {
                         issuers[i] = new X500Principal(asn1DerEncodedPrincipals[i]);
                     }
                 }
                 keyManagerHolder.setKeyMaterialClientSide(engine, keyTypes, issuers);
             } catch (Throwable cause) {
                 engine.initHandshakeException(cause);
                 if (cause instanceof Exception) {
                     throw (Exception) cause;
                 }
                 throw new SSLException(cause);
             }
         }
 
         /**
          * Gets the supported key types for client certificates.
          *
          * @param clientCertificateTypes {@code ClientCertificateType} values provided by the server.
          *        See https://www.ietf.org/assignments/tls-parameters/tls-parameters.xml.
          * @return supported key types that can be used in {@code X509KeyManager.chooseClientAlias} and
          *         {@code X509ExtendedKeyManager.chooseEngineClientAlias}.
          */
         private static Set<String> supportedClientKeyTypes(byte[] clientCertificateTypes) {
             if (clientCertificateTypes == null) {
                 // Try all of the supported key types.
                 return SUPPORTED_KEY_TYPES;
             }
             Set<String> result = new HashSet<>(clientCertificateTypes.length);
             for (byte keyTypeCode : clientCertificateTypes) {
                 String keyType = clientKeyType(keyTypeCode);
                 if (keyType == null) {
                     // Unsupported client key type -- ignore
                     continue;
                 }
                 result.add(keyType);
             }
             return result;
         }
 
         private static String clientKeyType(byte clientCertificateType) {
             // See also https://www.ietf.org/assignments/tls-parameters/tls-parameters.xml
             switch (clientCertificateType) {
                 case CertificateCallback.TLS_CT_RSA_SIGN:
                     return OpenSslKeyMaterialManager.KEY_TYPE_RSA; // RFC rsa_sign
                 case CertificateCallback.TLS_CT_RSA_FIXED_DH:
                     return OpenSslKeyMaterialManager.KEY_TYPE_DH_RSA; // RFC rsa_fixed_dh
                 case CertificateCallback.TLS_CT_ECDSA_SIGN:
                     return OpenSslKeyMaterialManager.KEY_TYPE_EC; // RFC ecdsa_sign
                 case CertificateCallback.TLS_CT_RSA_FIXED_ECDH:
                     return OpenSslKeyMaterialManager.KEY_TYPE_EC_RSA; // RFC rsa_fixed_ecdh
                 case CertificateCallback.TLS_CT_ECDSA_FIXED_ECDH:
                     return OpenSslKeyMaterialManager.KEY_TYPE_EC_EC; // RFC ecdsa_fixed_ecdh
                 default:
                     return null;
             }
         }
     }
 }