/*
 * ====================================================================
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF 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
 *
 *   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.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */

package org.apache.http.conn.ssl;

import java.io.IOException;
import java.io.InputStream;
import java.net.InetSocketAddress;
import java.net.Socket;
import java.security.cert.Certificate;
import java.security.cert.X509Certificate;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.List;

import javax.net.SocketFactory;
import javax.net.ssl.HostnameVerifier;
import javax.net.ssl.SSLContext;
import javax.net.ssl.SSLHandshakeException;
import javax.net.ssl.SSLPeerUnverifiedException;
import javax.net.ssl.SSLSession;
import javax.net.ssl.SSLSocket;
import javax.security.auth.x500.X500Principal;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.http.HttpHost;
import org.apache.http.annotation.Contract;
import org.apache.http.annotation.ThreadingBehavior;
import org.apache.http.conn.socket.LayeredConnectionSocketFactory;
import org.apache.http.conn.util.PublicSuffixMatcherLoader;
import org.apache.http.protocol.HttpContext;
import org.apache.http.ssl.SSLContexts;
import org.apache.http.util.Args;
import org.apache.http.util.TextUtils;

Layered socket factory for TLS/SSL connections.

SSLSocketFactory can be used to validate the identity of the HTTPS server against a list of
trusted certificates and to authenticate to the HTTPS server using a private key.
 SSLSocketFactory will enable server authentication when supplied with a trust-store file containing one or several trusted certificates. The client secure socket will reject the connection during the SSL session handshake if the target HTTPS server attempts to authenticate itself with a non-trusted certificate. 

Use JDK keytool utility to import a trusted certificate and generate a trust-store file:
   
    keytool -import -alias "my server cert" -file server.crt -keystore my.truststore
   
 In special cases the standard trust verification process can be bypassed by using a custom TrustStrategy. This interface is primarily intended for allowing self-signed certificates to be accepted as trusted without having to add them to the trust-store file. 
 SSLSocketFactory will enable client authentication when supplied with a key-store file containing a private key/public certificate pair. The client secure socket will use the private key to authenticate itself to the target HTTPS server during the SSL session handshake if requested to do so by the server. The target HTTPS server will in its turn verify the certificate presented by the client in order to establish client's authenticity. 

Use the following sequence of actions to generate a key-store file

  

    

     

     Use JDK keytool utility to generate a new key
     
     
keytool -genkey -v -alias "my client key" -validity 365 -keystore my.keystore
     

     For simplicity use the same password for the key as that of the key-store
     
    
    

     

     Issue a certificate signing request (CSR)
     
     
keytool -certreq -alias "my client key" -file mycertreq.csr -keystore my.keystore
    
    

     

     Send the certificate request to the trusted Certificate Authority for signature.
     One may choose to act as her own CA and sign the certificate request using a PKI
     tool, such as OpenSSL.
     
    
    

     

      Import the trusted CA root certificate
     
      
keytool -import -alias "my trusted ca" -file caroot.crt -keystore my.keystore
    
    

      

      Import the PKCS#7 file containing the complete certificate chain
      
      
keytool -import -alias "my client key" -file mycert.p7 -keystore my.keystore
    
    

      

      Verify the content of the resultant keystore file
      
      
keytool -list -v -keystore my.keystore
    
  
Since:
4.3/**
 * Layered socket factory for TLS/SSL connections.
 * <p>
 * SSLSocketFactory can be used to validate the identity of the HTTPS server against a list of
 * trusted certificates and to authenticate to the HTTPS server using a private key.
 * <p>
 * SSLSocketFactory will enable server authentication when supplied with
 * a {@link java.security.KeyStore trust-store} file containing one or several trusted certificates. The client
 * secure socket will reject the connection during the SSL session handshake if the target HTTPS
 * server attempts to authenticate itself with a non-trusted certificate.
 * <p>
 * Use JDK keytool utility to import a trusted certificate and generate a trust-store file:
 *    <pre>
 *     keytool -import -alias "my server cert" -file server.crt -keystore my.truststore
 *    </pre>
 * <p>
 * In special cases the standard trust verification process can be bypassed by using a custom
 * {@link org.apache.http.conn.ssl.TrustStrategy}. This interface is primarily intended for allowing self-signed
 * certificates to be accepted as trusted without having to add them to the trust-store file.
 * <p>
 * SSLSocketFactory will enable client authentication when supplied with
 * a {@link java.security.KeyStore key-store} file containing a private key/public certificate
 * pair. The client secure socket will use the private key to authenticate
 * itself to the target HTTPS server during the SSL session handshake if
 * requested to do so by the server.
 * The target HTTPS server will in its turn verify the certificate presented
 * by the client in order to establish client's authenticity.
 * <p>
 * Use the following sequence of actions to generate a key-store file
 * </p>
 *   <ul>
 *     <li>
 *      <p>
 *      Use JDK keytool utility to generate a new key
 *      </p>
 *      <pre>keytool -genkey -v -alias "my client key" -validity 365 -keystore my.keystore</pre>
 *      <p>
 *      For simplicity use the same password for the key as that of the key-store
 *      </p>
 *     </li>
 *     <li>
 *      <p>
 *      Issue a certificate signing request (CSR)
 *      </p>
 *      <pre>keytool -certreq -alias "my client key" -file mycertreq.csr -keystore my.keystore</pre>
 *     </li>
 *     <li>
 *      <p>
 *      Send the certificate request to the trusted Certificate Authority for signature.
 *      One may choose to act as her own CA and sign the certificate request using a PKI
 *      tool, such as OpenSSL.
 *      </p>
 *     </li>
 *     <li>
 *      <p>
 *       Import the trusted CA root certificate
 *      </p>
 *       <pre>keytool -import -alias "my trusted ca" -file caroot.crt -keystore my.keystore</pre>
 *     </li>
 *     <li>
 *       <p>
 *       Import the PKCS#7 file containing the complete certificate chain
 *       </p>
 *       <pre>keytool -import -alias "my client key" -file mycert.p7 -keystore my.keystore</pre>
 *     </li>
 *     <li>
 *       <p>
 *       Verify the content of the resultant keystore file
 *       </p>
 *       <pre>keytool -list -v -keystore my.keystore</pre>
 *     </li>
 *   </ul>
 *
 * @since 4.3
 */
@Contract(threading = ThreadingBehavior.SAFE)
@SuppressWarnings("deprecation")
public class SSLConnectionSocketFactory implements LayeredConnectionSocketFactory {

    public static final String TLS   = "TLS";
    public static final String SSL   = "SSL";
    public static final String SSLV2 = "SSLv2";

    
Deprecated:
Use AllowAllHostnameVerifier.INSTANCE./**
     * @deprecated Use {@link AllowAllHostnameVerifier#INSTANCE}.
     */
    @Deprecated
    public static final X509HostnameVerifier ALLOW_ALL_HOSTNAME_VERIFIER
        = AllowAllHostnameVerifier.INSTANCE;

    
Deprecated:
Use BrowserCompatHostnameVerifier.INSTANCE./**
     * @deprecated Use {@link BrowserCompatHostnameVerifier#INSTANCE}.
     */
    @Deprecated
    public static final X509HostnameVerifier BROWSER_COMPATIBLE_HOSTNAME_VERIFIER
        = BrowserCompatHostnameVerifier.INSTANCE;

    
Deprecated:
Use StrictHostnameVerifier.INSTANCE./**
     * @deprecated Use {@link StrictHostnameVerifier#INSTANCE}.
     */
    @Deprecated
    public static final X509HostnameVerifier STRICT_HOSTNAME_VERIFIER
        = StrictHostnameVerifier.INSTANCE;

    private final Log log = LogFactory.getLog(getClass());

    
Since:
4.4/**
     * @since 4.4
     */
    public static HostnameVerifier getDefaultHostnameVerifier() {
        return new DefaultHostnameVerifier(PublicSuffixMatcherLoader.getDefault());
    }

    
Obtains default SSL socket factory with an SSL context based on the standard JSSE trust material (cacerts file in the security properties directory). System properties are not taken into consideration. 
Returns:
default SSL socket factory/**
     * Obtains default SSL socket factory with an SSL context based on the standard JSSE
     * trust material ({@code cacerts} file in the security properties directory).
     * System properties are not taken into consideration.
     *
     * @return default SSL socket factory
     */
    public static SSLConnectionSocketFactory getSocketFactory() throws SSLInitializationException {
        return new SSLConnectionSocketFactory(SSLContexts.createDefault(), getDefaultHostnameVerifier());
    }

    private static String[] split(final String s) {
        if (TextUtils.isBlank(s)) {
            return null;
        }
        return s.split(" *, *");
    }

    
Obtains default SSL socket factory with an SSL context based on system properties
as described in

Java™ Secure Socket Extension (JSSE) Reference Guide.
Returns:
default system SSL socket factory/**
     * Obtains default SSL socket factory with an SSL context based on system properties
     * as described in
     * <a href="http://docs.oracle.com/javase/6/docs/technotes/guides/security/jsse/JSSERefGuide.html">
     * Java&#x2122; Secure Socket Extension (JSSE) Reference Guide</a>.
     *
     * @return default system SSL socket factory
     */
    public static SSLConnectionSocketFactory getSystemSocketFactory() throws SSLInitializationException {
        return new SSLConnectionSocketFactory(
            (javax.net.ssl.SSLSocketFactory) javax.net.ssl.SSLSocketFactory.getDefault(),
            split(System.getProperty("https.protocols")),
            split(System.getProperty("https.cipherSuites")),
            getDefaultHostnameVerifier());
    }

    private final javax.net.ssl.SSLSocketFactory socketfactory;
    private final HostnameVerifier hostnameVerifier;
    private final String[] supportedProtocols;
    private final String[] supportedCipherSuites;

    public SSLConnectionSocketFactory(final SSLContext sslContext) {
        this(sslContext, getDefaultHostnameVerifier());
    }

    
Deprecated:
(4.4) Use SSLConnectionSocketFactory(SSLContext, HostnameVerifier)/**
     * @deprecated (4.4) Use {@link #SSLConnectionSocketFactory(javax.net.ssl.SSLContext,
     *   javax.net.ssl.HostnameVerifier)}
     */
    @Deprecated
    public SSLConnectionSocketFactory(
            final SSLContext sslContext, final X509HostnameVerifier hostnameVerifier) {
        this(Args.notNull(sslContext, "SSL context").getSocketFactory(),
                null, null, hostnameVerifier);
    }

    
Deprecated:
(4.4) Use SSLConnectionSocketFactory(SSLContext, String[], String[], HostnameVerifier)/**
     * @deprecated (4.4) Use {@link #SSLConnectionSocketFactory(javax.net.ssl.SSLContext,
     *   String[], String[], javax.net.ssl.HostnameVerifier)}
     */
    @Deprecated
    public SSLConnectionSocketFactory(
            final SSLContext sslContext,
            final String[] supportedProtocols,
            final String[] supportedCipherSuites,
            final X509HostnameVerifier hostnameVerifier) {
        this(Args.notNull(sslContext, "SSL context").getSocketFactory(),
                supportedProtocols, supportedCipherSuites, hostnameVerifier);
    }

    
Deprecated:
(4.4) Use SSLConnectionSocketFactory(SSLSocketFactory, HostnameVerifier)/**
     * @deprecated (4.4) Use {@link #SSLConnectionSocketFactory(javax.net.ssl.SSLSocketFactory,
     *   javax.net.ssl.HostnameVerifier)}
     */
    @Deprecated
    public SSLConnectionSocketFactory(
            final javax.net.ssl.SSLSocketFactory socketfactory,
            final X509HostnameVerifier hostnameVerifier) {
        this(socketfactory, null, null, hostnameVerifier);
    }

    
Deprecated:
(4.4) Use SSLConnectionSocketFactory(SSLSocketFactory, String[], String[], HostnameVerifier)/**
     * @deprecated (4.4) Use {@link #SSLConnectionSocketFactory(javax.net.ssl.SSLSocketFactory,
     *   String[], String[], javax.net.ssl.HostnameVerifier)}
     */
    @Deprecated
    public SSLConnectionSocketFactory(
            final javax.net.ssl.SSLSocketFactory socketfactory,
            final String[] supportedProtocols,
            final String[] supportedCipherSuites,
            final X509HostnameVerifier hostnameVerifier) {
        this(socketfactory, supportedProtocols, supportedCipherSuites, (HostnameVerifier) hostnameVerifier);
    }

    
Since:
4.4/**
     * @since 4.4
     */
    public SSLConnectionSocketFactory(
            final SSLContext sslContext, final HostnameVerifier hostnameVerifier) {
        this(Args.notNull(sslContext, "SSL context").getSocketFactory(),
                null, null, hostnameVerifier);
    }

    
Since:
4.4/**
     * @since 4.4
     */
    public SSLConnectionSocketFactory(
            final SSLContext sslContext,
            final String[] supportedProtocols,
            final String[] supportedCipherSuites,
            final HostnameVerifier hostnameVerifier) {
        this(Args.notNull(sslContext, "SSL context").getSocketFactory(),
                supportedProtocols, supportedCipherSuites, hostnameVerifier);
    }

    
Since:
4.4/**
     * @since 4.4
     */
    public SSLConnectionSocketFactory(
            final javax.net.ssl.SSLSocketFactory socketfactory,
            final HostnameVerifier hostnameVerifier) {
        this(socketfactory, null, null, hostnameVerifier);
    }

    
Since:
4.4/**
     * @since 4.4
     */
    public SSLConnectionSocketFactory(
            final javax.net.ssl.SSLSocketFactory socketfactory,
            final String[] supportedProtocols,
            final String[] supportedCipherSuites,
            final HostnameVerifier hostnameVerifier) {
        this.socketfactory = Args.notNull(socketfactory, "SSL socket factory");
        this.supportedProtocols = supportedProtocols;
        this.supportedCipherSuites = supportedCipherSuites;
        this.hostnameVerifier = hostnameVerifier != null ? hostnameVerifier : getDefaultHostnameVerifier();
    }

    
Performs any custom initialization for a newly created SSLSocket (before the SSL handshake happens). The default implementation is a no-op, but could be overridden to, e.g., call SSLSocket.setEnabledCipherSuites(String[]). 
Throws:
IOException – may be thrown if overridden/**
     * Performs any custom initialization for a newly created SSLSocket
     * (before the SSL handshake happens).
     *
     * The default implementation is a no-op, but could be overridden to, e.g.,
     * call {@link javax.net.ssl.SSLSocket#setEnabledCipherSuites(String[])}.
     * @throws IOException may be thrown if overridden
     */
    protected void prepareSocket(final SSLSocket socket) throws IOException {
    }

    @Override
    public Socket createSocket(final HttpContext context) throws IOException {
        return SocketFactory.getDefault().createSocket();
    }

    @Override
    public Socket connectSocket(
            final int connectTimeout,
            final Socket socket,
            final HttpHost host,
            final InetSocketAddress remoteAddress,
            final InetSocketAddress localAddress,
            final HttpContext context) throws IOException {
        Args.notNull(host, "HTTP host");
        Args.notNull(remoteAddress, "Remote address");
        final Socket sock = socket != null ? socket : createSocket(context);
        if (localAddress != null) {
            sock.bind(localAddress);
        }
        try {
            if (connectTimeout > 0 && sock.getSoTimeout() == 0) {
                sock.setSoTimeout(connectTimeout);
            }
            if (this.log.isDebugEnabled()) {
                this.log.debug("Connecting socket to " + remoteAddress + " with timeout " + connectTimeout);
            }
            sock.connect(remoteAddress, connectTimeout);
        } catch (final IOException ex) {
            try {
                sock.close();
            } catch (final IOException ignore) {
            }
            throw ex;
        }
        // Setup SSL layering if necessary
        if (sock instanceof SSLSocket) {
            final SSLSocket sslsock = (SSLSocket) sock;
            this.log.debug("Starting handshake");
            sslsock.startHandshake();
            verifyHostname(sslsock, host.getHostName());
            return sock;
        }
        return createLayeredSocket(sock, host.getHostName(), remoteAddress.getPort(), context);
    }

    @Override
    public Socket createLayeredSocket(
            final Socket socket,
            final String target,
            final int port,
            final HttpContext context) throws IOException {
        final SSLSocket sslsock = (SSLSocket) this.socketfactory.createSocket(
                socket,
                target,
                port,
                true);
        if (supportedProtocols != null) {
            sslsock.setEnabledProtocols(supportedProtocols);
        } else {
            // If supported protocols are not explicitly set, remove all SSL protocol versions
            final String[] allProtocols = sslsock.getEnabledProtocols();
            final List<String> enabledProtocols = new ArrayList<String>(allProtocols.length);
            for (final String protocol: allProtocols) {
                if (!protocol.startsWith("SSL")) {
                    enabledProtocols.add(protocol);
                }
            }
            if (!enabledProtocols.isEmpty()) {
                sslsock.setEnabledProtocols(enabledProtocols.toArray(new String[enabledProtocols.size()]));
            }
        }
        if (supportedCipherSuites != null) {
            sslsock.setEnabledCipherSuites(supportedCipherSuites);
        }

        if (this.log.isDebugEnabled()) {
            this.log.debug("Enabled protocols: " + Arrays.asList(sslsock.getEnabledProtocols()));
            this.log.debug("Enabled cipher suites:" + Arrays.asList(sslsock.getEnabledCipherSuites()));
        }

        prepareSocket(sslsock);
        this.log.debug("Starting handshake");
        sslsock.startHandshake();
        verifyHostname(sslsock, target);
        return sslsock;
    }

    private void verifyHostname(final SSLSocket sslsock, final String hostname) throws IOException {
        try {
            SSLSession session = sslsock.getSession();
            if (session == null) {
                // In our experience this only happens under IBM 1.4.x when
                // spurious (unrelated) certificates show up in the server'
                // chain.  Hopefully this will unearth the real problem:
                final InputStream in = sslsock.getInputStream();
                in.available();
                // If ssl.getInputStream().available() didn't cause an
                // exception, maybe at least now the session is available?
                session = sslsock.getSession();
                if (session == null) {
                    // If it's still null, probably a startHandshake() will
                    // unearth the real problem.
                    sslsock.startHandshake();
                    session = sslsock.getSession();
                }
            }
            if (session == null) {
                throw new SSLHandshakeException("SSL session not available");
            }

            if (this.log.isDebugEnabled()) {
                this.log.debug("Secure session established");
                this.log.debug(" negotiated protocol: " + session.getProtocol());
                this.log.debug(" negotiated cipher suite: " + session.getCipherSuite());

                try {

                    final Certificate[] certs = session.getPeerCertificates();
                    final X509Certificate x509 = (X509Certificate) certs[0];
                    final X500Principal peer = x509.getSubjectX500Principal();

                    this.log.debug(" peer principal: " + peer.toString());
                    final Collection<List<?>> altNames1 = x509.getSubjectAlternativeNames();
                    if (altNames1 != null) {
                        final List<String> altNames = new ArrayList<String>();
                        for (final List<?> aC : altNames1) {
                            if (!aC.isEmpty()) {
                                altNames.add((String) aC.get(1));
                            }
                        }
                        this.log.debug(" peer alternative names: " + altNames);
                    }

                    final X500Principal issuer = x509.getIssuerX500Principal();
                    this.log.debug(" issuer principal: " + issuer.toString());
                    final Collection<List<?>> altNames2 = x509.getIssuerAlternativeNames();
                    if (altNames2 != null) {
                        final List<String> altNames = new ArrayList<String>();
                        for (final List<?> aC : altNames2) {
                            if (!aC.isEmpty()) {
                                altNames.add((String) aC.get(1));
                            }
                        }
                        this.log.debug(" issuer alternative names: " + altNames);
                    }
                } catch (final Exception ignore) {
                }
            }

            if (!this.hostnameVerifier.verify(hostname, session)) {
                final Certificate[] certs = session.getPeerCertificates();
                final X509Certificate x509 = (X509Certificate) certs[0];
                final List<SubjectName> subjectAlts = DefaultHostnameVerifier.getSubjectAltNames(x509);
                throw new SSLPeerUnverifiedException("Certificate for <" + hostname + "> doesn't match any " +
                        "of the subject alternative names: " + subjectAlts);
            }
            // verifyHostName() didn't blowup - good!
        } catch (final IOException iox) {
            // close the socket before re-throwing the exception
            try { sslsock.close(); } catch (final Exception x) { /*ignore*/ }
            throw iox;
        }
    }

}