/*

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * particular file as subject to the "Classpath" exception as provided

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 */

package sun.security.ssl;

import java.io.*;

import java.net.*;

import java.security.GeneralSecurityException;

import java.security.AccessController;

import java.security.AccessControlContext;

import java.security.PrivilegedAction;

import java.util.*;

import java.util.concurrent.TimeUnit;

import java.util.concurrent.locks.ReentrantLock;

import javax.crypto.BadPaddingException;

import javax.net.ssl.*;

import com.sun.net.ssl.internal.ssl.X509ExtendedTrustManager;

/**

 * Implementation of an SSL socket.  This is a normal connection type

 * socket, implementing SSL over some lower level socket, such as TCP.

 * Because it is layered over some lower level socket, it MUST override

 * all default socket methods.

 *

 * <P> This API offers a non-traditional option for establishing SSL

 * connections.  You may first establish the connection directly, then pass

 * that connection to the SSL socket constructor with a flag saying which

 * role should be taken in the handshake protocol.  (The two ends of the

 * connection must not choose the same role!)  This allows setup of SSL

 * proxying or tunneling, and also allows the kind of "role reversal"

 * that is required for most FTP data transfers.

 *

 * @see javax.net.ssl.SSLSocket

 * @see SSLServerSocket

 *

 * @author David Brownell

 */

final public class SSLSocketImpl extends BaseSSLSocketImpl {

    /*

     * ERROR HANDLING GUIDELINES

     * (which exceptions to throw and catch and which not to throw and catch)

     *

     * . if there is an IOException (SocketException) when accessing the

     *   underlying Socket, pass it through

     *

     * . do not throw IOExceptions, throw SSLExceptions (or a subclass)

     *

     * . for internal errors (things that indicate a bug in JSSE or a

     *   grossly misconfigured J2RE), throw either an SSLException or

     *   a RuntimeException at your convenience.

     *

     * . handshaking code (Handshaker or HandshakeMessage) should generally

     *   pass through exceptions, but can handle them if they know what to

     *   do.

     *

     * . exception chaining should be used for all new code. If you happen

     *   to touch old code that does not use chaining, you should change it.

     *

     * . there is a top level exception handler that sits at all entry

     *   points from application code to SSLSocket read/write code. It

     *   makes sure that all errors are handled (see handleException()).

     *

     * . JSSE internal code should generally not call close(), call

     *   closeInternal().

     */

    /*

     * There's a state machine associated with each connection, which

     * among other roles serves to negotiate session changes.

     *

     * - START with constructor, until the TCP connection's around.

     * - HANDSHAKE picks session parameters before allowing traffic.

     *          There are many substates due to sequencing requirements

     *          for handshake messages.

     * - DATA may be transmitted.

     * - RENEGOTIATE state allows concurrent data and handshaking

     *          traffic ("same" substates as HANDSHAKE), and terminates

     *          in selection of new session (and connection) parameters

     * - ERROR state immediately precedes abortive disconnect.

     * - SENT_CLOSE sent a close_notify to the peer. For layered,

     *          non-autoclose socket, must now read close_notify

     *          from peer before closing the connection. For nonlayered or

     *          non-autoclose socket, close connection and go onto

     *          cs_CLOSED state.

     * - CLOSED after sending close_notify alert, & socket is closed.

     *          SSL connection objects are not reused.

     * - APP_CLOSED once the application calls close(). Then it behaves like

     *          a closed socket, e.g.. getInputStream() throws an Exception.

     *

     * State affects what SSL record types may legally be sent:

     *

     * - Handshake ... only in HANDSHAKE and RENEGOTIATE states

     * - App Data ... only in DATA and RENEGOTIATE states

     * - Alert ... in HANDSHAKE, DATA, RENEGOTIATE

     *

     * Re what may be received:  same as what may be sent, except that

     * HandshakeRequest handshaking messages can come from servers even

     * in the application data state, to request entry to RENEGOTIATE.

     *

     * The state machine within HANDSHAKE and RENEGOTIATE states controls

     * the pending session, not the connection state, until the change

     * cipher spec and "Finished" handshake messages are processed and

     * make the "new" session become the current one.

     *

     * NOTE: details of the SMs always need to be nailed down better.

     * The text above illustrates the core ideas.

     *

     *                +---->-------+------>--------->-------+

     *                |            |                        |

     *     <-----<    ^            ^  <-----<               v

     *START>----->HANDSHAKE>----->DATA>----->RENEGOTIATE  SENT_CLOSE

     *                v            v               v        |   |

     *                |            |               |        |   v

     *                +------------+---------------+        v ERROR

     *                |                                     |   |

     *                v                                     |   |

     *               ERROR>------>----->CLOSED<--------<----+-- +

     *                                     |

     *                                     v

     *                                 APP_CLOSED

     *

     * ALSO, note that the the purpose of handshaking (renegotiation is

     * included) is to assign a different, and perhaps new, session to

     * the connection.  The SSLv3 spec is a bit confusing on that new

     * protocol feature.

     */

    private static final int    cs_START = 0;

    private static final int    cs_HANDSHAKE = 1;

    private static final int    cs_DATA = 2;

    private static final int    cs_RENEGOTIATE = 3;

    private static final int    cs_ERROR = 4;

    private static final int   cs_SENT_CLOSE = 5;

    private static final int    cs_CLOSED = 6;

    private static final int    cs_APP_CLOSED = 7;

    /*

     * Client authentication be off, requested, or required.

     *

     * Migrated to SSLEngineImpl:

     *    clauth_none/cl_auth_requested/clauth_required

     */

    /*

     * Drives the protocol state machine.

     */

    private int                 connectionState;

    /*

     * Flag indicating if the next record we receive MUST be a Finished

     * message. Temporarily set during the handshake to ensure that

     * a change cipher spec message is followed by a finished message.

     */

    private boolean             expectingFinished;

    /*

     * For improved diagnostics, we detail connection closure

     * If the socket is closed (connectionState >= cs_ERROR),

     * closeReason != null indicates if the socket was closed

     * because of an error or because or normal shutdown.

     */

    private SSLException        closeReason;

    /*

     * Per-connection private state that doesn't change when the

     * session is changed.

     */

    private byte                doClientAuth;

    private boolean             roleIsServer;

    private CipherSuiteList     enabledCipherSuites;

    private boolean             enableSessionCreation = true;

    private String              host;

    private boolean             autoClose = true;

    private AccessControlContext acc;

    // hostname identification algorithm, the hostname identification is

    // disabled by default.

    private String              identificationAlg = null;

    /*

     * READ ME * READ ME * READ ME * READ ME * READ ME * READ ME *

     * IMPORTANT STUFF TO UNDERSTANDING THE SYNCHRONIZATION ISSUES.

     * READ ME * READ ME * READ ME * READ ME * READ ME * READ ME *

     *

     * There are several locks here.

     *

     * The primary lock is the per-instance lock used by

     * synchronized(this) and the synchronized methods.  It controls all

     * access to things such as the connection state and variables which

     * affect handshaking.  If we are inside a synchronized method, we

     * can access the state directly, otherwise, we must use the

     * synchronized equivalents.

     *

     * The handshakeLock is used to ensure that only one thread performs

     * the *complete initial* handshake.  If someone is handshaking, any

     * stray application or startHandshake() requests who find the

     * connection state is cs_HANDSHAKE will stall on handshakeLock

     * until handshaking is done.  Once the handshake is done, we either

     * succeeded or failed, but we can never go back to the cs_HANDSHAKE

     * or cs_START state again.

     *

     * Note that the read/write() calls here in SSLSocketImpl are not

     * obviously synchronized.  In fact, it's very nonintuitive, and

     * requires careful examination of code paths.  Grab some coffee,

     * and be careful with any code changes.

     *

     * There can be only three threads active at a time in the I/O

     * subsection of this class.

     *    1.  startHandshake

     *    2.  AppInputStream

     *    3.  AppOutputStream

     * One thread could call startHandshake().

     * AppInputStream/AppOutputStream read() and write() calls are each

     * synchronized on 'this' in their respective classes, so only one

     * app. thread will be doing a SSLSocketImpl.read() or .write()'s at

     * a time.

     *

     * If handshaking is required (state cs_HANDSHAKE), and

     * getConnectionState() for some/all threads returns cs_HANDSHAKE,

     * only one can grab the handshakeLock, and the rest will stall

     * either on getConnectionState(), or on the handshakeLock if they

     * happen to successfully race through the getConnectionState().

     *

     * If a writer is doing the initial handshaking, it must create a

     * temporary reader to read the responses from the other side.  As a

     * side-effect, the writer's reader will have priority over any

     * other reader.  However, the writer's reader is not allowed to

     * consume any application data.  When handshakeLock is finally

     * released, we either have a cs_DATA connection, or a

     * cs_CLOSED/cs_ERROR socket.

     *

     * The writeLock is held while writing on a socket connection and

     * also to protect the MAC and cipher for their direction.  The

     * writeLock is package private for Handshaker which holds it while

     * writing the ChangeCipherSpec message.

     *

     * To avoid the problem of a thread trying to change operational

     * modes on a socket while handshaking is going on, we synchronize

     * on 'this'.  If handshaking has not started yet, we tell the

     * handshaker to change its mode.  If handshaking has started,

     * we simply store that request until the next pending session

     * is created, at which time the new handshaker's state is set.

     *

     * The readLock is held during readRecord(), which is responsible

     * for reading an InputRecord, decrypting it, and processing it.

     * The readLock ensures that these three steps are done atomically

     * and that once started, no other thread can block on InputRecord.read.

     * This is necessary so that processing of close_notify alerts

     * from the peer are handled properly.

     */

    private Object              handshakeLock;

    ReentrantLock               writeLock;

    private Object              readLock;

    private InputRecord         inrec;

    /*

     * Crypto state that's reinitialized when the session changes.

     */

    private MAC                 readMAC, writeMAC;

    private CipherBox           readCipher, writeCipher;

    // NOTE: compression state would be saved here

    /*

     * The authentication context holds all information used to establish

     * who this end of the connection is (certificate chains, private keys,

     * etc) and who is trusted (e.g. as CAs or websites).

     */

    private SSLContextImpl      sslContext;

    /*

     * This connection is one of (potentially) many associated with

     * any given session.  The output of the handshake protocol is a

     * new session ... although all the protocol description talks

     * about changing the cipher spec (and it does change), in fact

     * that's incidental since it's done by changing everything that

     * is associated with a session at the same time.  (TLS/IETF may

     * change that to add client authentication w/o new key exchg.)

     */

    private SSLSessionImpl      sess;

    private Handshaker          handshaker;

    /*

     * If anyone wants to get notified about handshake completions,

     * they'll show up on this list.

     */

    private HashMap<HandshakeCompletedListener, AccessControlContext>

                                                        handshakeListeners;

    /*

     * Reuse the same internal input/output streams.

     */

    private InputStream         sockInput;

    private OutputStream        sockOutput;

    /*

     * These input and output streams block their data in SSL records,

     * and usually arrange integrity and privacy protection for those

     * records.  The guts of the SSL protocol are wrapped up in these

     * streams, and in the handshaking that establishes the details of

     * that integrity and privacy protection.

     */

    private AppInputStream      input;

    private AppOutputStream     output;

    /*

     * The protocols we support are SSL Version 3.0) and

     * TLS (version 3.1).

     * In addition we support a pseudo protocol called

     * SSLv2Hello which when set will result in an SSL v2 Hello

     * being sent with SSLv3 or TLSv1 version info.

     */

    private ProtocolList enabledProtocols;

    /*

     * The SSL version associated with this connection.

     */

    private ProtocolVersion     protocolVersion = ProtocolVersion.DEFAULT;

    /* Class and subclass dynamic debugging support */

    private static final Debug debug = Debug.getInstance("ssl");

    //

    // CONSTRUCTORS AND INITIALIZATION CODE

    //

    /**

     * Constructs an SSL connection to a named host at a specified port,

     * using the authentication context provided.  This endpoint acts as

     * the client, and may rejoin an existing SSL session if appropriate.

     *

     * @param context authentication context to use

     * @param host name of the host with which to connect

     * @param port number of the server's port

     */

    SSLSocketImpl(SSLContextImpl context, String host, int port)

            throws IOException, UnknownHostException {

        super();

        this.host = host;

        init(context, false);

        SocketAddress socketAddress =

               host != null ? new InetSocketAddress(host, port) :

               new InetSocketAddress(InetAddress.getByName(null), port);

        connect(socketAddress, 0);

    }

    /**

     * Constructs an SSL connection to a server at a specified address.

     * and TCP port, using the authentication context provided.  This

     * endpoint acts as the client, and may rejoin an existing SSL session

     * if appropriate.

     *

     * @param context authentication context to use

     * @param address the server's host

     * @param port its port

     */

    SSLSocketImpl(SSLContextImpl context, InetAddress host, int port)

            throws IOException {

        super();

        init(context, false);

        SocketAddress socketAddress = new InetSocketAddress(host, port);

        connect(socketAddress, 0);

    }

    /**

     * Constructs an SSL connection to a named host at a specified port,

     * using the authentication context provided.  This endpoint acts as

     * the client, and may rejoin an existing SSL session if appropriate.

     *

     * @param context authentication context to use

     * @param host name of the host with which to connect

     * @param port number of the server's port

     * @param localAddr the local address the socket is bound to

     * @param localPort the local port the socket is bound to

     */

    SSLSocketImpl(SSLContextImpl context, String host, int port,

            InetAddress localAddr, int localPort)

            throws IOException, UnknownHostException {

        super();

        this.host = host;

        init(context, false);

        bind(new InetSocketAddress(localAddr, localPort));

        SocketAddress socketAddress =

               host != null ? new InetSocketAddress(host, port) :

               new InetSocketAddress(InetAddress.getByName(null), port);

        connect(socketAddress, 0);

    }

    /**

     * Constructs an SSL connection to a server at a specified address.

     * and TCP port, using the authentication context provided.  This

     * endpoint acts as the client, and may rejoin an existing SSL session

     * if appropriate.

     *

     * @param context authentication context to use

     * @param address the server's host

     * @param port its port

     * @param localAddr the local address the socket is bound to

     * @param localPort the local port the socket is bound to

     */

    SSLSocketImpl(SSLContextImpl context, InetAddress host, int port,

            InetAddress localAddr, int localPort)

            throws IOException {

        super();

        init(context, false);

        bind(new InetSocketAddress(localAddr, localPort));

        SocketAddress socketAddress = new InetSocketAddress(host, port);

        connect(socketAddress, 0);

    }

    /*

     * Package-private constructor used ONLY by SSLServerSocket.  The

     * java.net package accepts the TCP connection after this call is

     * made.  This just initializes handshake state to use "server mode",

     * giving control over the use of SSL client authentication.

     */

    SSLSocketImpl(SSLContextImpl context, boolean serverMode,

            CipherSuiteList suites, byte clientAuth,

            boolean sessionCreation, ProtocolList protocols)

            throws IOException {

        super();

        doClientAuth = clientAuth;

        enableSessionCreation = sessionCreation;

        init(context, serverMode);

        /*

         * Override what was picked out for us.

         */

        enabledCipherSuites = suites;

        enabledProtocols = protocols;

    }

    /**

     * Package-private constructor used to instantiate an unconnected

     * socket. The java.net package will connect it, either when the

     * connect() call is made by the application.  This instance is

     * meant to set handshake state to use "client mode".

     */

    SSLSocketImpl(SSLContextImpl context) {

        super();

        init(context, false);

    }

    /**

     * Layer SSL traffic over an existing connection, rather than creating

     * a new connection.  The existing connection may be used only for SSL

     * traffic (using this SSLSocket) until the SSLSocket.close() call

     * returns. However, if a protocol error is detected, that existing

     * connection is automatically closed.

     *

     * <P> This particular constructor always uses the socket in the

     * role of an SSL client. It may be useful in cases which start

     * using SSL after some initial data transfers, for example in some

     * SSL tunneling applications or as part of some kinds of application

     * protocols which negotiate use of a SSL based security.

     *

     * @param sock the existing connection

     * @param context the authentication context to use

     */

    SSLSocketImpl(SSLContextImpl context, Socket sock, String host,

            int port, boolean autoClose) throws IOException {

        super(sock);

        // We always layer over a connected socket

        if (!sock.isConnected()) {

            throw new SocketException("Underlying socket is not connected");

        }

        this.host = host;

        init(context, false);

        this.autoClose = autoClose;

        doneConnect();

    }

    /**

     * Initializes the client socket.

     */

    private void init(SSLContextImpl context, boolean isServer) {

        sslContext = context;

        sess = SSLSessionImpl.nullSession;

        /*

         * role is as specified, state is START until after

         * the low level connection's established.

         */

        roleIsServer = isServer;

        connectionState = cs_START;

        /*

         * default read and write side cipher and MAC support

         *

         * Note:  compression support would go here too

         */

        readCipher = CipherBox.NULL;