/*
    * 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.netty.internal.tcnative.SniHostNameMatcher;
  import io.netty5.buffer.api.DefaultBufferAllocators;
  import io.netty5.util.CharsetUtil;
  import io.netty5.util.internal.logging.InternalLogger;
  import io.netty5.util.internal.logging.InternalLoggerFactory;
  
  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 java.security.KeyStore;
  import java.security.PrivateKey;
  import java.security.cert.X509Certificate;
  import java.util.Map;
  
  import static java.util.Objects.requireNonNull;
  
  /**
   * A server-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 ReferenceCountedOpenSslServerContext extends ReferenceCountedOpenSslContext {
      private static final InternalLogger logger =
              InternalLoggerFactory.getInstance(ReferenceCountedOpenSslServerContext.class);
      private static final byte[] ID = {'n', 'e', 't', 't', 'y'};
      private final OpenSslServerSessionContext sessionContext;
  
      ReferenceCountedOpenSslServerContext(
              X509Certificate[] trustCertCollection, TrustManagerFactory trustManagerFactory,
              X509Certificate[] keyCertChain, PrivateKey key, String keyPassword, KeyManagerFactory keyManagerFactory,
              Iterable<String> ciphers, CipherSuiteFilter cipherFilter, ApplicationProtocolConfig apn,
              long sessionCacheSize, long sessionTimeout, ClientAuth clientAuth, String[] protocols, boolean startTls,
              boolean enableOcsp, String keyStore, Map.Entry<SslContextOption<?>, Object>... options)
              throws SSLException {
          this(trustCertCollection, trustManagerFactory, keyCertChain, key, keyPassword, keyManagerFactory, ciphers,
                  cipherFilter, toNegotiator(apn), sessionCacheSize, sessionTimeout, clientAuth, protocols, startTls,
                  enableOcsp, keyStore, options);
      }
  
      ReferenceCountedOpenSslServerContext(
              X509Certificate[] trustCertCollection, TrustManagerFactory trustManagerFactory,
              X509Certificate[] keyCertChain, PrivateKey key, String keyPassword, KeyManagerFactory keyManagerFactory,
              Iterable<String> ciphers, CipherSuiteFilter cipherFilter, OpenSslApplicationProtocolNegotiator apn,
              long sessionCacheSize, long sessionTimeout, ClientAuth clientAuth, String[] protocols, boolean startTls,
              boolean enableOcsp, String keyStore, Map.Entry<SslContextOption<?>, Object>... options)
              throws SSLException {
          super(ciphers, cipherFilter, apn, SSL.SSL_MODE_SERVER, keyCertChain,
                clientAuth, protocols, startTls, enableOcsp, true, options);
          // Create a new SSL_CTX and configure it.
          boolean success = false;
          try {
              sessionContext = newSessionContext(this, ctx, engineMap, trustCertCollection, trustManagerFactory,
                      keyCertChain, key, keyPassword, keyManagerFactory, keyStore,
                      sessionCacheSize, sessionTimeout);
              if (SERVER_ENABLE_SESSION_TICKET) {
                  sessionContext.setTicketKeys();
              }
              success = true;
          } finally {
              if (!success) {
                  release();
              }
          }
      }
  
      @Override
      public OpenSslServerSessionContext sessionContext() {
          return sessionContext;
      }
  
      static OpenSslServerSessionContext 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 {
         OpenSslKeyMaterialProvider keyMaterialProvider = null;
         try {
             try {
                 SSLContext.setVerify(ctx, SSL.SSL_CVERIFY_NONE, VERIFY_DEPTH);
                 if (!OpenSsl.supportsKeyManagerFactory()) {
                     if (keyManagerFactory != null) {
                         throw new IllegalArgumentException(
                                 "KeyManagerFactory not supported");
                     }
                     requireNonNull(keyCertChain, "keyCertChain");
 
                     setKeyMaterial(ctx, keyCertChain, key, keyPassword);
                 } else {
                     // javadocs state that keyManagerFactory has precedent over keyCertChain, and we must have a
                     // keyManagerFactory for the server so build one if it is not specified.
                     if (keyManagerFactory == 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);
 
                     SSLContext.setCertificateCallback(ctx, new OpenSslServerCertificateCallback(
                             engineMap, new OpenSslKeyMaterialManager(keyMaterialProvider)));
                 }
             } catch (Exception e) {
                 throw new SSLException("failed to set certificate and key", e);
             }
             try {
                 if (trustCertCollection != null) {
                     trustManagerFactory = buildTrustManagerFactory(trustCertCollection, trustManagerFactory, keyStore);
                 } else if (trustManagerFactory == null) {
                     // Mimic the way SSLContext.getInstance(KeyManager[], null, null) works
                     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));
                 }
 
                 X509Certificate[] issuers = manager.getAcceptedIssuers();
                 if (issuers != null && issuers.length > 0) {
                     long bio = 0;
                     try {
                         bio = toBIO(DefaultBufferAllocators.offHeapAllocator(), issuers);
                         if (!SSLContext.setCACertificateBio(ctx, bio)) {
                             throw new SSLException("unable to setup accepted issuers for trustmanager " + manager);
                         }
                     } finally {
                         freeBio(bio);
                     }
                 }
 
                 // IMPORTANT: The callbacks set for hostname matching 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 matcher.
                 SSLContext.setSniHostnameMatcher(ctx, new OpenSslSniHostnameMatcher(engineMap));
             } catch (SSLException e) {
                 throw e;
             } catch (Exception e) {
                 throw new SSLException("unable to setup trustmanager", e);
             }
 
             OpenSslServerSessionContext sessionContext = new OpenSslServerSessionContext(thiz, keyMaterialProvider);
             sessionContext.setSessionIdContext(ID);
             // Enable session caching by default
             sessionContext.setSessionCacheEnabled(SERVER_ENABLE_SESSION_CACHE);
             if (sessionCacheSize > 0) {
                 sessionContext.setSessionCacheSize((int) Math.min(sessionCacheSize, Integer.MAX_VALUE));
             }
             if (sessionTimeout > 0) {
                 sessionContext.setSessionTimeout((int) Math.min(sessionTimeout, Integer.MAX_VALUE));
             }
 
             keyMaterialProvider = null;
 
             return sessionContext;
         } finally {
             if (keyMaterialProvider != null) {
                 keyMaterialProvider.destroy();
             }
         }
     }
 
     private static final class OpenSslServerCertificateCallback implements CertificateCallback {
         private final OpenSslEngineMap engineMap;
         private final OpenSslKeyMaterialManager keyManagerHolder;
 
         OpenSslServerCertificateCallback(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);
             if (engine == null) {
                 // Maybe null if destroyed in the meantime.
                 return;
             }
             try {
                 // For now we just ignore the asn1DerEncodedPrincipals as this is kind of inline with what the
                 // OpenJDK SSLEngineImpl does.
                 keyManagerHolder.setKeyMaterialServerSide(engine);
             } catch (Throwable cause) {
                 engine.initHandshakeException(cause);
 
                 if (cause instanceof Exception) {
                     throw (Exception) cause;
                 }
                 throw new SSLException(cause);
             }
         }
     }
 
     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.checkClientTrusted(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.checkClientTrusted(peerCerts, auth, engine);
         }
     }
 
     private static final class OpenSslSniHostnameMatcher implements SniHostNameMatcher {
         private final OpenSslEngineMap engineMap;
 
         OpenSslSniHostnameMatcher(OpenSslEngineMap engineMap) {
             this.engineMap = engineMap;
         }
 
         @Override
         public boolean match(long ssl, String hostname) {
             ReferenceCountedOpenSslEngine engine = engineMap.get(ssl);
             if (engine != null) {
                 // TODO: In the next release of tcnative we should pass the byte[] directly in and not use a String.
                 return engine.checkSniHostnameMatch(hostname.getBytes(CharsetUtil.UTF_8));
             }
             logger.warn("No ReferenceCountedOpenSslEngine found for SSL pointer: {}", ssl);
             return false;
         }
     }
 }