/*
 * Copyright (C) 2017 The Android Open Source Project
 *
 * 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
 *
 *      http://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.conscrypt;

import java.nio.ByteBuffer;
import java.security.KeyManagementException;
import java.security.PrivateKey;
import java.security.Provider;
import java.security.cert.X509Certificate;
import javax.net.ssl.HostnameVerifier;
import javax.net.ssl.HttpsURLConnection;
import javax.net.ssl.SSLContext;
import javax.net.ssl.SSLContextSpi;
import javax.net.ssl.SSLEngine;
import javax.net.ssl.SSLEngineResult;
import javax.net.ssl.SSLException;
import javax.net.ssl.SSLServerSocketFactory;
import javax.net.ssl.SSLSession;
import javax.net.ssl.SSLSessionContext;
import javax.net.ssl.SSLSocket;
import javax.net.ssl.SSLSocketFactory;
import javax.net.ssl.TrustManager;
import javax.net.ssl.X509TrustManager;

/**
 * Core API for creating and configuring all Conscrypt types.
 * This is identical to the original Conscrypt.java, except with the slow
 * version initialization code removed.
 */
@SuppressWarnings("unused")
public final class ConscryptSignal {
  private ConscryptSignal() {}

  /**
   * Returns {@code true} if the Conscrypt native library has been successfully loaded.
   */
  public static boolean isAvailable() {
    try {
      checkAvailability();
      return true;
    } catch (Throwable e) {
      return false;
    }
  }

  // BEGIN MODIFICATION
  /*public static class Version {
    private final int major;
    private final int minor;
    private final int patch;

    private Version(int major, int minor, int patch) {
      this.major = major;
      this.minor = minor;
      this.patch = patch;
    }

    public int major() { return major; }
    public int minor() { return minor; }
    public int patch() { return patch; }
  }

  private static final Version VERSION;

  static {
    int major = -1;
    int minor = -1;
    int patch = -1;
    InputStream stream = null;
    try {
      stream = Conscrypt.class.getResourceAsStream("conscrypt.properties");
      if (stream != null) {
        Properties props = new Properties();
        props.load(stream);
        major = Integer.parseInt(props.getProperty("org.conscrypt.version.major", "-1"));
        minor = Integer.parseInt(props.getProperty("org.conscrypt.version.minor", "-1"));
        patch = Integer.parseInt(props.getProperty("org.conscrypt.version.patch", "-1"));
      }
    } catch (IOException e) {
      // TODO(prb): This should probably be fatal or have some fallback behaviour
    } finally {
      IoUtils.closeQuietly(stream);
    }
    if ((major >= 0) && (minor >= 0) && (patch >= 0)) {
      VERSION = new Version(major, minor, patch);
    } else {
      VERSION = null;
    }
  }

  /**
   * Returns the version of this distribution of Conscrypt.  If version information is
   * unavailable, returns {@code null}.
   */
  /*public static Version version() {
    return VERSION;
  }*/

  // END MODIFICATION

  /**
   * Checks that the Conscrypt support is available for the system.
   *
   * @throws UnsatisfiedLinkError if unavailable
   */
  public static void checkAvailability() {
    NativeCrypto.checkAvailability();
  }

  /**
   * Indicates whether the given {@link Provider} was created by this distribution of Conscrypt.
   */
  public static boolean isConscrypt(Provider provider) {
    return provider instanceof OpenSSLProvider;
  }

  /**
   * Constructs a new {@link Provider} with the default name.
   */
  public static Provider newProvider() {
    checkAvailability();
    return new OpenSSLProvider();
  }

  /**
   * Constructs a new {@link Provider} with the given name.
   *
   * @deprecated Use {@link #newProviderBuilder()} instead.
   */
  @Deprecated
  public static Provider newProvider(String providerName) {
    checkAvailability();
    return newProviderBuilder().setName(providerName).build();
  }

  public static class ProviderBuilder {
    private String name = Platform.getDefaultProviderName();
    private boolean provideTrustManager = Platform.provideTrustManagerByDefault();
    private String defaultTlsProtocol = NativeCrypto.SUPPORTED_PROTOCOL_TLSV1_3;

    private ProviderBuilder() {}

    /**
     * Sets the name of the Provider to be built.
     */
    public ProviderBuilder setName(String name) {
      this.name = name;
      return this;
    }

    /**
     * Causes the returned provider to provide an implementation of
     * {@link javax.net.ssl.TrustManagerFactory}.
     * @deprecated Use provideTrustManager(true)
     */
    @Deprecated
    public ProviderBuilder provideTrustManager() {
      return provideTrustManager(true);
    }

    /**
     * Specifies whether the returned provider will provide an implementation of
     * {@link javax.net.ssl.TrustManagerFactory}.
     */
    public ProviderBuilder provideTrustManager(boolean provide) {
      this.provideTrustManager = provide;
      return this;
    }

    /**
     * Specifies what the default TLS protocol should be for SSLContext identifiers
     * {@code TLS}, {@code SSL}, and {@code Default}.
     */
    public ProviderBuilder defaultTlsProtocol(String defaultTlsProtocol) {
      this.defaultTlsProtocol = defaultTlsProtocol;
      return this;
    }

    public Provider build() {
      return new OpenSSLProvider(name, provideTrustManager, defaultTlsProtocol);
    }
  }

  public static ProviderBuilder newProviderBuilder() {
    return new ProviderBuilder();
  }

  /**
   * Returns the maximum length (in bytes) of an encrypted packet.
   */
  public static int maxEncryptedPacketLength() {
    return NativeConstants.SSL3_RT_MAX_PACKET_SIZE;
  }

  /**
   * Gets the default X.509 trust manager.
   */
  @ExperimentalApi
  public static X509TrustManager getDefaultX509TrustManager() throws KeyManagementException {
    checkAvailability();
    return SSLParametersImpl.getDefaultX509TrustManager();
  }

  /**
   * Indicates whether the given {@link SSLContext} was created by this distribution of Conscrypt.
   */
  public static boolean isConscrypt(SSLContext context) {
    return context.getProvider() instanceof OpenSSLProvider;
  }

  /**
   * Constructs a new instance of the preferred {@link SSLContextSpi}.
   */
  public static SSLContextSpi newPreferredSSLContextSpi() {
    checkAvailability();
    return OpenSSLContextImpl.getPreferred();
  }

  /**
   * Sets the client-side persistent cache to be used by the context.
   */
  public static void setClientSessionCache(SSLContext context, SSLClientSessionCache cache) {
    SSLSessionContext clientContext = context.getClientSessionContext();
    if (!(clientContext instanceof ClientSessionContext)) {
      throw new IllegalArgumentException(
          "Not a conscrypt client context: " + clientContext.getClass().getName());
    }
    ((ClientSessionContext) clientContext).setPersistentCache(cache);
  }

  /**
   * Sets the server-side persistent cache to be used by the context.
   */
  public static void setServerSessionCache(SSLContext context, SSLServerSessionCache cache) {
    SSLSessionContext serverContext = context.getServerSessionContext();
    if (!(serverContext instanceof ServerSessionContext)) {
      throw new IllegalArgumentException(
          "Not a conscrypt client context: " + serverContext.getClass().getName());
    }
    ((ServerSessionContext) serverContext).setPersistentCache(cache);
  }

  /**
   * Indicates whether the given {@link SSLSocketFactory} was created by this distribution of
   * Conscrypt.
   */
  public static boolean isConscrypt(SSLSocketFactory factory) {
    return factory instanceof OpenSSLSocketFactoryImpl;
  }

  private static OpenSSLSocketFactoryImpl toConscrypt(SSLSocketFactory factory) {
    if (!isConscrypt(factory)) {
      throw new IllegalArgumentException(
          "Not a conscrypt socket factory: " + factory.getClass().getName());
    }
    return (OpenSSLSocketFactoryImpl) factory;
  }

  /**
   * Configures the default socket to be created for all socket factory instances.
   */
  @ExperimentalApi
  public static void setUseEngineSocketByDefault(boolean useEngineSocket) {
    OpenSSLSocketFactoryImpl.setUseEngineSocketByDefault(useEngineSocket);
    OpenSSLServerSocketFactoryImpl.setUseEngineSocketByDefault(useEngineSocket);
  }

  /**
   * Configures the socket to be created for the given socket factory instance.
   */
  @ExperimentalApi
  public static void setUseEngineSocket(SSLSocketFactory factory, boolean useEngineSocket) {
    toConscrypt(factory).setUseEngineSocket(useEngineSocket);
  }

  /**
   * Indicates whether the given {@link SSLServerSocketFactory} was created by this distribution
   * of Conscrypt.
   */
  public static boolean isConscrypt(SSLServerSocketFactory factory) {
    return factory instanceof OpenSSLServerSocketFactoryImpl;
  }

  private static OpenSSLServerSocketFactoryImpl toConscrypt(SSLServerSocketFactory factory) {
    if (!isConscrypt(factory)) {
      throw new IllegalArgumentException(
          "Not a conscrypt server socket factory: " + factory.getClass().getName());
    }
    return (OpenSSLServerSocketFactoryImpl) factory;
  }

  /**
   * Configures the socket to be created for the given server socket factory instance.
   */
  @ExperimentalApi
  public static void setUseEngineSocket(SSLServerSocketFactory factory, boolean useEngineSocket) {
    toConscrypt(factory).setUseEngineSocket(useEngineSocket);
  }

  /**
   * Indicates whether the given {@link SSLSocket} was created by this distribution of Conscrypt.
   */
  public static boolean isConscrypt(SSLSocket socket) {
    return socket instanceof AbstractConscryptSocket;
  }

  private static AbstractConscryptSocket toConscrypt(SSLSocket socket) {
    if (!isConscrypt(socket)) {
      throw new IllegalArgumentException(
          "Not a conscrypt socket: " + socket.getClass().getName());
    }
    return (AbstractConscryptSocket) socket;
  }

  /**
   * This method enables Server Name Indication (SNI) and overrides the hostname supplied
   * during socket creation.  If the hostname is not a valid SNI hostname, the SNI extension
   * will be omitted from the handshake.
   *
   * @param socket the socket
   * @param hostname the desired SNI hostname, or null to disable
   */
  public static void setHostname(SSLSocket socket, String hostname) {
    toConscrypt(socket).setHostname(hostname);
  }

  /**
   * Returns either the hostname supplied during socket creation or via
   * {@link #setHostname(SSLSocket, String)}. No DNS resolution is attempted before
   * returning the hostname.
   */
  public static String getHostname(SSLSocket socket) {
    return toConscrypt(socket).getHostname();
  }

  /**
   * This method attempts to create a textual representation of the peer host or IP. Does
   * not perform a reverse DNS lookup. This is typically used during session creation.
   */
  public static String getHostnameOrIP(SSLSocket socket) {
    return toConscrypt(socket).getHostnameOrIP();
  }

  /**
   * This method enables session ticket support.
   *
   * @param socket the socket
   * @param useSessionTickets True to enable session tickets
   */
  public static void setUseSessionTickets(SSLSocket socket, boolean useSessionTickets) {
    toConscrypt(socket).setUseSessionTickets(useSessionTickets);
  }

  /**
   * Enables/disables TLS Channel ID for the given server-side socket.
   *
   * <p>This method needs to be invoked before the handshake starts.
   *
   * @param socket the socket
   * @param enabled Whether to enable channel ID.
   * @throws IllegalStateException if this is a client socket or if the handshake has already
   * started.
   */
  public static void setChannelIdEnabled(SSLSocket socket, boolean enabled) {
    toConscrypt(socket).setChannelIdEnabled(enabled);
  }

  /**
   * Gets the TLS Channel ID for the given server-side socket. Channel ID is only available
   * once the handshake completes.
   *
   * @param socket the socket
   * @return channel ID or {@code null} if not available.
   * @throws IllegalStateException if this is a client socket or if the handshake has not yet
   * completed.
   * @throws SSLException if channel ID is available but could not be obtained.
   */
  public static byte[] getChannelId(SSLSocket socket) throws SSLException {
    return toConscrypt(socket).getChannelId();
  }

  /**
   * Sets the {@link PrivateKey} to be used for TLS Channel ID by this client socket.
   *
   * <p>This method needs to be invoked before the handshake starts.
   *
   * @param socket the socket
   * @param privateKey private key (enables TLS Channel ID) or {@code null} for no key
   * (disables TLS Channel ID).
   * The private key must be an Elliptic Curve (EC) key based on the NIST P-256 curve (aka
   * SECG secp256r1 or ANSI
   * X9.62 prime256v1).
   * @throws IllegalStateException if this is a server socket or if the handshake has already
   * started.
   */
  public static void setChannelIdPrivateKey(SSLSocket socket, PrivateKey privateKey) {
    toConscrypt(socket).setChannelIdPrivateKey(privateKey);
  }

  /**
   * Returns the ALPN protocol agreed upon by client and server.
   *
   * @param socket the socket
   * @return the selected protocol or {@code null} if no protocol was agreed upon.
   */
  public static String getApplicationProtocol(SSLSocket socket) {
    return toConscrypt(socket).getApplicationProtocol();
  }

  /**
   * Sets an application-provided ALPN protocol selector. If provided, this will override
   * the list of protocols set by {@link #setApplicationProtocols(SSLSocket, String[])}.
   *
   * @param socket the socket
   * @param selector the ALPN protocol selector
   */
  public static void setApplicationProtocolSelector(SSLSocket socket,
                                                    ApplicationProtocolSelector selector) {
    toConscrypt(socket).setApplicationProtocolSelector(selector);
  }

  /**
   * Sets the application-layer protocols (ALPN) in prioritization order.
   *
   * @param socket the socket being configured
   * @param protocols the protocols in descending order of preference. If empty, no protocol
   * indications will be used. This array will be copied.
   * @throws IllegalArgumentException - if protocols is null, or if any element in a non-empty
   * array is null or an empty (zero-length) string
   */
  public static void setApplicationProtocols(SSLSocket socket, String[] protocols) {
    toConscrypt(socket).setApplicationProtocols(protocols);
  }

  /**
   * Gets the application-layer protocols (ALPN) in prioritization order.
   *
   * @param socket the socket
   * @return the protocols in descending order of preference, or an empty array if protocol
   * indications are not being used. Always returns a new array.
   */
  public static String[] getApplicationProtocols(SSLSocket socket) {
    return toConscrypt(socket).getApplicationProtocols();
  }

  /**
   * Returns the tls-unique channel binding value for this connection, per RFC 5929.  This
   * will return {@code null} if there is no such value available, such as if the handshake
   * has not yet completed or this connection is closed.
   */
  public static byte[] getTlsUnique(SSLSocket socket) {
    return toConscrypt(socket).getTlsUnique();
  }

  /**
   * Exports a value derived from the TLS master secret as described in RFC 5705.
   *
   * @param label the label to use in calculating the exported value.  This must be
   * an ASCII-only string.
   * @param context the application-specific context value to use in calculating the
   * exported value.  This may be {@code null} to use no application context, which is
   * treated differently than an empty byte array.
   * @param length the number of bytes of keying material to return.
   * @return a value of the specified length, or {@code null} if the handshake has not yet
   * completed or the connection has been closed.
   * @throws SSLException if the value could not be exported.
   */
  public static byte[] exportKeyingMaterial(SSLSocket socket, String label, byte[] context,
                                            int length) throws SSLException {
    return toConscrypt(socket).exportKeyingMaterial(label, context, length);
  }

  /**
   * Indicates whether the given {@link SSLEngine} was created by this distribution of Conscrypt.
   */
  public static boolean isConscrypt(SSLEngine engine) {
    return engine instanceof AbstractConscryptEngine;
  }

  private static AbstractConscryptEngine toConscrypt(SSLEngine engine) {
    if (!isConscrypt(engine)) {
      throw new IllegalArgumentException(
          "Not a conscrypt engine: " + engine.getClass().getName());
    }
    return (AbstractConscryptEngine) engine;
  }

  /**
   * Provides the given engine with the provided bufferAllocator.
   * @throws IllegalArgumentException if the provided engine is not a Conscrypt engine.
   * @throws IllegalStateException if the provided engine has already begun its handshake.
   */
  @ExperimentalApi
  public static void setBufferAllocator(SSLEngine engine, BufferAllocator bufferAllocator) {
    toConscrypt(engine).setBufferAllocator(bufferAllocator);
  }

  /**
   * Provides the given socket with the provided bufferAllocator.  If the given socket is a
   * Conscrypt socket but does not use buffer allocators, this method does nothing.
   * @throws IllegalArgumentException if the provided socket is not a Conscrypt socket.
   * @throws IllegalStateException if the provided socket has already begun its handshake.
   */
  @ExperimentalApi
  public static void setBufferAllocator(SSLSocket socket, BufferAllocator bufferAllocator) {
    AbstractConscryptSocket s = toConscrypt(socket);
    if (s instanceof ConscryptEngineSocket) {
      ((ConscryptEngineSocket) s).setBufferAllocator(bufferAllocator);
    }
  }

  /**
   * Configures the default {@link BufferAllocator} to be used by all future
   * {@link SSLEngine} instances from this provider.
   */
  @ExperimentalApi
  public static void setDefaultBufferAllocator(BufferAllocator bufferAllocator) {
    ConscryptEngine.setDefaultBufferAllocator(bufferAllocator);
  }

  /**
   * This method enables Server Name Indication (SNI) and overrides the hostname supplied
   * during engine creation.
   *
   * @param engine the engine
   * @param hostname the desired SNI hostname, or {@code null} to disable
   */
  public static void setHostname(SSLEngine engine, String hostname) {
    toConscrypt(engine).setHostname(hostname);
  }

  /**
   * Returns either the hostname supplied during socket creation or via
   * {@link #setHostname(SSLEngine, String)}. No DNS resolution is attempted before
   * returning the hostname.
   */
  public static String getHostname(SSLEngine engine) {
    return toConscrypt(engine).getHostname();
  }

  /**
   * Returns the maximum overhead, in bytes, of sealing a record with SSL.
   */
  public static int maxSealOverhead(SSLEngine engine) {
    return toConscrypt(engine).maxSealOverhead();
  }

  /**
   * Sets a listener on the given engine for completion of the TLS handshake
   */
  public static void setHandshakeListener(SSLEngine engine, HandshakeListener handshakeListener) {
    toConscrypt(engine).setHandshakeListener(handshakeListener);
  }

  /**
   * Enables/disables TLS Channel ID for the given server-side engine.
   *
   * <p>This method needs to be invoked before the handshake starts.
   *
   * @param engine the engine
   * @param enabled Whether to enable channel ID.
   * @throws IllegalStateException if this is a client engine or if the handshake has already
   * started.
   */
  public static void setChannelIdEnabled(SSLEngine engine, boolean enabled) {
    toConscrypt(engine).setChannelIdEnabled(enabled);
  }

  /**
   * Gets the TLS Channel ID for the given server-side engine. Channel ID is only available
   * once the handshake completes.
   *
   * @param engine the engine
   * @return channel ID or {@code null} if not available.
   * @throws IllegalStateException if this is a client engine or if the handshake has not yet
   * completed.
   * @throws SSLException if channel ID is available but could not be obtained.
   */
  public static byte[] getChannelId(SSLEngine engine) throws SSLException {
    return toConscrypt(engine).getChannelId();
  }

  /**
   * Sets the {@link PrivateKey} to be used for TLS Channel ID by this client engine.
   *
   * <p>This method needs to be invoked before the handshake starts.
   *
   * @param engine the engine
   * @param privateKey private key (enables TLS Channel ID) or {@code null} for no key
   * (disables TLS Channel ID).
   * The private key must be an Elliptic Curve (EC) key based on the NIST P-256 curve (aka
   * SECG secp256r1 or ANSI X9.62 prime256v1).
   * @throws IllegalStateException if this is a server engine or if the handshake has already
   * started.
   */
  public static void setChannelIdPrivateKey(SSLEngine engine, PrivateKey privateKey) {
    toConscrypt(engine).setChannelIdPrivateKey(privateKey);
  }

  /**
   * Extended unwrap method for multiple source and destination buffers.
   *
   * @param engine the target engine for the unwrap
   * @param srcs the source buffers
   * @param dsts the destination buffers
   * @return the result of the unwrap operation
   * @throws SSLException thrown if an SSL error occurred
   */
  public static SSLEngineResult unwrap(SSLEngine engine, final ByteBuffer[] srcs,
                                       final ByteBuffer[] dsts) throws SSLException {
    return toConscrypt(engine).unwrap(srcs, dsts);
  }

  /**
   * Exteneded unwrap method for multiple source and destination buffers.
   *
   * @param engine the target engine for the unwrap.
   * @param srcs the source buffers
   * @param srcsOffset the offset in the {@code srcs} array of the first source buffer
   * @param srcsLength the number of source buffers starting at {@code srcsOffset}
   * @param dsts the destination buffers
   * @param dstsOffset the offset in the {@code dsts} array of the first destination buffer
   * @param dstsLength the number of destination buffers starting at {@code dstsOffset}
   * @return the result of the unwrap operation
   * @throws SSLException thrown if an SSL error occurred
   */
  public static SSLEngineResult unwrap(SSLEngine engine, final ByteBuffer[] srcs, int srcsOffset,
                                       final int srcsLength, final ByteBuffer[] dsts, final int dstsOffset,
                                       final int dstsLength) throws SSLException {
    return toConscrypt(engine).unwrap(
        srcs, srcsOffset, srcsLength, dsts, dstsOffset, dstsLength);
  }

  /**
   * This method enables session ticket support.
   *
   * @param engine the engine
   * @param useSessionTickets True to enable session tickets
   */
  public static void setUseSessionTickets(SSLEngine engine, boolean useSessionTickets) {
    toConscrypt(engine).setUseSessionTickets(useSessionTickets);
  }

  /**
   * Sets the application-layer protocols (ALPN) in prioritization order.
   *
   * @param engine the engine being configured
   * @param protocols the protocols in descending order of preference. If empty, no protocol
   * indications will be used.  This array will be copied.
   * @throws IllegalArgumentException - if protocols is null, or if any element in a non-empty
   * array is null or an empty (zero-length) string
   */
  public static void setApplicationProtocols(SSLEngine engine, String[] protocols) {
    toConscrypt(engine).setApplicationProtocols(protocols);
  }

  /**
   * Gets the application-layer protocols (ALPN) in prioritization order.
   *
   * @param engine the engine
   * @return the protocols in descending order of preference, or an empty array if protocol
   * indications are not being used. Always returns a new array.
   */
  public static String[] getApplicationProtocols(SSLEngine engine) {
    return toConscrypt(engine).getApplicationProtocols();
  }

  /**
   * Sets an application-provided ALPN protocol selector. If provided, this will override
   * the list of protocols set by {@link #setApplicationProtocols(SSLEngine, String[])}.
   *
   * @param engine the engine
   * @param selector the ALPN protocol selector
   */
  public static void setApplicationProtocolSelector(SSLEngine engine,
                                                    ApplicationProtocolSelector selector) {
    toConscrypt(engine).setApplicationProtocolSelector(selector);
  }

  /**
   * Returns the ALPN protocol agreed upon by client and server.
   *
   * @param engine the engine
   * @return the selected protocol or {@code null} if no protocol was agreed upon.
   */
  public static String getApplicationProtocol(SSLEngine engine) {
    return toConscrypt(engine).getApplicationProtocol();
  }

  /**
   * Returns the tls-unique channel binding value for this connection, per RFC 5929.  This
   * will return {@code null} if there is no such value available, such as if the handshake
   * has not yet completed or this connection is closed.
   */
  public static byte[] getTlsUnique(SSLEngine engine) {
    return toConscrypt(engine).getTlsUnique();
  }

  /**
   * Exports a value derived from the TLS master secret as described in RFC 5705.
   *
   * @param label the label to use in calculating the exported value.  This must be
   * an ASCII-only string.
   * @param context the application-specific context value to use in calculating the
   * exported value.  This may be {@code null} to use no application context, which is
   * treated differently than an empty byte array.
   * @param length the number of bytes of keying material to return.
   * @return a value of the specified length, or {@code null} if the handshake has not yet
   * completed or the connection has been closed.
   * @throws SSLException if the value could not be exported.
   */
  public static byte[] exportKeyingMaterial(SSLEngine engine, String label, byte[] context,
                                            int length) throws SSLException {
    return toConscrypt(engine).exportKeyingMaterial(label, context, length);
  }

  /**
   * Indicates whether the given {@link TrustManager} was created by this distribution of
   * Conscrypt.
   */
  public static boolean isConscrypt(TrustManager trustManager) {
    return trustManager instanceof TrustManagerImpl;
  }

  private static TrustManagerImpl toConscrypt(TrustManager trustManager) {
    if (!isConscrypt(trustManager)) {
      throw new IllegalArgumentException(
          "Not a Conscrypt trust manager: " + trustManager.getClass().getName());
    }
    return (TrustManagerImpl) trustManager;
  }

  /**
   * Set the default hostname verifier that will be used for HTTPS endpoint identification by
   * Conscrypt trust managers.  If {@code null} (the default), endpoint identification will use
   * the default hostname verifier set in
   * {@link HttpsURLConnection#setDefaultHostnameVerifier(javax.net.ssl.HostnameVerifier)}.
   */
  public synchronized static void setDefaultHostnameVerifier(ConscryptHostnameVerifier verifier) {
    TrustManagerImpl.setDefaultHostnameVerifier(verifier);
  }

  /**
   * Returns the currently-set default hostname verifier for Conscrypt trust managers.
   *
   * @see #setDefaultHostnameVerifier(ConscryptHostnameVerifier)
   */
  public synchronized static ConscryptHostnameVerifier getDefaultHostnameVerifier(TrustManager trustManager) {
    return TrustManagerImpl.getDefaultHostnameVerifier();
  }

  /**
   * Set the hostname verifier that will be used for HTTPS endpoint identification by the
   * given trust manager.  If {@code null} (the default), endpoint identification will use the
   * default hostname verifier set in {@link #setDefaultHostnameVerifier(ConscryptHostnameVerifier)}.
   *
   * @throws IllegalArgumentException if the provided trust manager is not a Conscrypt trust
   * manager per {@link #isConscrypt(TrustManager)}
   */
  public static void setHostnameVerifier(TrustManager trustManager, ConscryptHostnameVerifier verifier) {
    toConscrypt(trustManager).setHostnameVerifier(verifier);
  }

  /**
   * Returns the currently-set hostname verifier for the given trust manager.
   *
   * @throws IllegalArgumentException if the provided trust manager is not a Conscrypt trust
   * manager per {@link #isConscrypt(TrustManager)}
   *
   * @see #setHostnameVerifier(TrustManager, ConscryptHostnameVerifier)
   */
  public static ConscryptHostnameVerifier getHostnameVerifier(TrustManager trustManager) {
    return toConscrypt(trustManager).getHostnameVerifier();
  }

  /**
   * Wraps the HttpsURLConnection.HostnameVerifier into a ConscryptHostnameVerifier
   */
  public static ConscryptHostnameVerifier wrapHostnameVerifier(final HostnameVerifier verifier) {
    return  new ConscryptHostnameVerifier() {
      @Override
      public boolean verify(X509Certificate[] certificates, String hostname, SSLSession session) {
        return verifier.verify(hostname, session);
      }
    };
  }
}