/*

 * Copyright (c) 2000, 2019, Oracle and/or its affiliates. All rights reserved.

 * 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

 * published by the Free Software Foundation.  Oracle designates this

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

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * 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.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package java.net;

import java.io.IOException;

import java.io.InputStream;

import java.io.OutputStream;

import java.io.BufferedOutputStream;

import java.security.AccessController;

import java.util.Iterator;

import jdk.internal.util.StaticProperty;

import sun.net.SocksProxy;

import sun.net.spi.DefaultProxySelector;

import sun.net.www.ParseUtil;

/**

 * SOCKS (V4 & V5) TCP socket implementation (RFC 1928).

 */

class SocksSocketImpl extends DelegatingSocketImpl implements SocksConsts {

    private String server = null;

    private int serverPort = DEFAULT_PORT;

    private InetSocketAddress external_address;

    private boolean useV4 = false;

    private Socket cmdsock = null;

    private InputStream cmdIn = null;

    private OutputStream cmdOut = null;

    SocksSocketImpl(SocketImpl delegate) {

        super(delegate);

    }

    SocksSocketImpl(Proxy proxy, SocketImpl delegate) {

        super(delegate);

        SocketAddress a = proxy.address();

        if (a instanceof InetSocketAddress) {

            InetSocketAddress ad = (InetSocketAddress) a;

            // Use getHostString() to avoid reverse lookups

            server = ad.getHostString();

            serverPort = ad.getPort();

        }

        useV4 = useV4(proxy);

    }

    private static boolean useV4(Proxy proxy) {

        if (proxy instanceof SocksProxy

            && ((SocksProxy)proxy).protocolVersion() == 4) {

            return true;

        }

        return DefaultProxySelector.socksProxyVersion() == 4;

    }

    private synchronized void privilegedConnect(final String host,

                                              final int port,

                                              final int timeout)

        throws IOException

    {

        try {

            AccessController.doPrivileged(

                new java.security.PrivilegedExceptionAction<>() {

                    public Void run() throws IOException {

                              superConnectServer(host, port, timeout);

                              cmdIn = getInputStream();

                              cmdOut = getOutputStream();

                              return null;

                          }

                      });

        } catch (java.security.PrivilegedActionException pae) {

            throw (IOException) pae.getException();

        }

    }

    private void superConnectServer(String host, int port,

                                    int timeout) throws IOException {

        delegate.connect(new InetSocketAddress(host, port), timeout);

    }

    private static int remainingMillis(long deadlineMillis) throws IOException {

        if (deadlineMillis == 0L)

            return 0;

        final long remaining = deadlineMillis - System.currentTimeMillis();

        if (remaining > 0)

            return (int) remaining;

        throw new SocketTimeoutException();

    }

    private int readSocksReply(InputStream in, byte[] data, long deadlineMillis) throws IOException {

        int len = data.length;

        int received = 0;

        int originalTimeout = (int) getOption(SocketOptions.SO_TIMEOUT);

        try {

            while (received < len) {

                int count;

                int remaining = remainingMillis(deadlineMillis);

                setOption(SocketOptions.SO_TIMEOUT, remaining);

                try {

                    count = in.read(data, received, len - received);

                } catch (SocketTimeoutException e) {

                    throw new SocketTimeoutException("Connect timed out");

                }

                if (count < 0)

                    throw new SocketException("Malformed reply from SOCKS server");

                received += count;

            }

        } finally {

            setOption(SocketOptions.SO_TIMEOUT, originalTimeout);

        }

        return received;

    }

    private boolean authenticate(byte method, InputStream in,

                                 BufferedOutputStream out,

                                 long deadlineMillis) throws IOException {

        // No Authentication required. We're done then!

        if (method == NO_AUTH)

            return true;

        /*

         * User/Password authentication. Try, in that order :

         * - The application provided Authenticator, if any

         * - the user.name & no password (backward compatibility behavior).

         */

        if (method == USER_PASSW) {

            String userName;

            String password = null;

            final InetAddress addr = InetAddress.getByName(server);

            PasswordAuthentication pw =

                java.security.AccessController.doPrivileged(

                    new java.security.PrivilegedAction<>() {

                        public PasswordAuthentication run() {

                                return Authenticator.requestPasswordAuthentication(

                                       server, addr, serverPort, "SOCKS5", "SOCKS authentication", null);

                            }

                        });

            if (pw != null) {

                userName = pw.getUserName();

                password = new String(pw.getPassword());

            } else {

                userName = StaticProperty.userName();

            }

            if (userName == null)

                return false;

            out.write(1);

            out.write(userName.length());

            try {

                out.write(userName.getBytes("ISO-8859-1"));

            } catch (java.io.UnsupportedEncodingException uee) {

                assert false;

            }

            if (password != null) {

                out.write(password.length());

                try {

                    out.write(password.getBytes("ISO-8859-1"));

                } catch (java.io.UnsupportedEncodingException uee) {

                    assert false;

                }

            } else

                out.write(0);

            out.flush();

            byte[] data = new byte[2];

            int i = readSocksReply(in, data, deadlineMillis);

            if (i != 2 || data[1] != 0) {

                /* RFC 1929 specifies that the connection MUST be closed if

                   authentication fails */

                out.close();

                in.close();

                return false;

            }

            /* Authentication succeeded */

            return true;

        }

        return false;

    }

    private void connectV4(InputStream in, OutputStream out,

                           InetSocketAddress endpoint,

                           long deadlineMillis) throws IOException {

        if (!(endpoint.getAddress() instanceof Inet4Address)) {

            throw new SocketException("SOCKS V4 requires IPv4 only addresses");

        }

        out.write(PROTO_VERS4);

        out.write(CONNECT);

        out.write((endpoint.getPort() >> 8) & 0xff);

        out.write((endpoint.getPort() >> 0) & 0xff);

        out.write(endpoint.getAddress().getAddress());

        String userName = getUserName();

        try {

            out.write(userName.getBytes("ISO-8859-1"));

        } catch (java.io.UnsupportedEncodingException uee) {

            assert false;

        }

        out.write(0);

        out.flush();

        byte[] data = new byte[8];

        int n = readSocksReply(in, data, deadlineMillis);

        if (n != 8)

            throw new SocketException("Reply from SOCKS server has bad length: " + n);

        if (data[0] != 0 && data[0] != 4)

            throw new SocketException("Reply from SOCKS server has bad version");

        SocketException ex = null;

        switch (data[1]) {

        case 90:

            // Success!

            external_address = endpoint;

            break;

        case 91:

            ex = new SocketException("SOCKS request rejected");

            break;

        case 92:

            ex = new SocketException("SOCKS server couldn't reach destination");

            break;

        case 93:

            ex = new SocketException("SOCKS authentication failed");

            break;

        default:

            ex = new SocketException("Reply from SOCKS server contains bad status");

            break;

        }

        if (ex != null) {

            in.close();

            out.close();

            throw ex;

        }

    }

    @Override

    protected void connect(String host, int port) throws IOException {

        connect(new InetSocketAddress(host, port), 0);

    }

    @Override

    protected void connect(InetAddress address, int port) throws IOException {

        connect(new InetSocketAddress(address, port), 0);

    }

    /**

     * Connects the Socks Socket to the specified endpoint. It will first

     * connect to the SOCKS proxy and negotiate the access. If the proxy

     * grants the connections, then the connect is successful and all

     * further traffic will go to the "real" endpoint.

     *

     * @param   endpoint        the {@code SocketAddress} to connect to.

     * @param   timeout         the timeout value in milliseconds

     * @throws  IOException     if the connection can't be established.

     * @throws  SecurityException if there is a security manager and it

     *                          doesn't allow the connection

     * @throws  IllegalArgumentException if endpoint is null or a

     *          SocketAddress subclass not supported by this socket

     */

    @Override

    protected void connect(SocketAddress endpoint, int timeout) throws IOException {

        final long deadlineMillis;

        if (timeout == 0) {

            deadlineMillis = 0L;

        } else {

            long finish = System.currentTimeMillis() + timeout;

            deadlineMillis = finish < 0 ? Long.MAX_VALUE : finish;

        }

        SecurityManager security = System.getSecurityManager();

        if (endpoint == null || !(endpoint instanceof InetSocketAddress))

            throw new IllegalArgumentException("Unsupported address type");

        InetSocketAddress epoint = (InetSocketAddress) endpoint;

        if (security != null) {

            if (epoint.isUnresolved())

                security.checkConnect(epoint.getHostName(),

                                      epoint.getPort());

            else

                security.checkConnect(epoint.getAddress().getHostAddress(),

                                      epoint.getPort());

        }

        if (server == null) {

            // This is the general case

            // server is not null only when the socket was created with a

            // specified proxy in which case it does bypass the ProxySelector

            ProxySelector sel = java.security.AccessController.doPrivileged(

                new java.security.PrivilegedAction<>() {

                    public ProxySelector run() {

                            return ProxySelector.getDefault();

                        }

                    });

            if (sel == null) {

                /*

                 * No default proxySelector --> direct connection

                 */

                delegate.connect(epoint, remainingMillis(deadlineMillis));

                return;

            }

            URI uri;

            // Use getHostString() to avoid reverse lookups

            String host = epoint.getHostString();

            // IPv6 literal?

            if (epoint.getAddress() instanceof Inet6Address &&

                (!host.startsWith("[")) && (host.indexOf(':') >= 0)) {

                host = "[" + host + "]";

            }

            try {

                uri = new URI("socket://" + ParseUtil.encodePath(host) + ":"+ epoint.getPort());

            } catch (URISyntaxException e) {

                // This shouldn't happen

                assert false : e;

                uri = null;

            }

            Proxy p = null;

            IOException savedExc = null;

            final Iterator<Proxy> iProxy;

            try {

                iProxy = sel.select(uri).iterator();

            } catch (IllegalArgumentException iae) {

                throw new IOException("Failed to select a proxy", iae);

            }

            if (iProxy == null || !(iProxy.hasNext())) {

                delegate.connect(epoint, remainingMillis(deadlineMillis));

                return;

            }

            while (iProxy.hasNext()) {

                p = iProxy.next();

                if (p == null || p.type() != Proxy.Type.SOCKS) {

                    delegate.connect(epoint, remainingMillis(deadlineMillis));

                    return;

                }

                if (!(p.address() instanceof InetSocketAddress))

                    throw new SocketException("Unknown address type for proxy: " + p);

                // Use getHostString() to avoid reverse lookups

                server = ((InetSocketAddress) p.address()).getHostString();

                serverPort = ((InetSocketAddress) p.address()).getPort();

                useV4 = useV4(p);

                // Connects to the SOCKS server

                try {

                    privilegedConnect(server, serverPort, remainingMillis(deadlineMillis));

                    // Worked, let's get outta here

                    break;

                } catch (IOException e) {

                    // Ooops, let's notify the ProxySelector

                    sel.connectFailed(uri,p.address(),e);

                    server = null;

                    serverPort = -1;

                    savedExc = e;

                    // Will continue the while loop and try the next proxy

                }

            }

            /*

             * If server is still null at this point, none of the proxy

             * worked

             */

            if (server == null) {

                throw new SocketException("Can't connect to SOCKS proxy:"

                                          + savedExc.getMessage());

            }

        } else {

            // Connects to the SOCKS server

            try {

                privilegedConnect(server, serverPort, remainingMillis(deadlineMillis));

            } catch (IOException e) {

                throw new SocketException(e.getMessage());

            }

        }

        // cmdIn & cmdOut were initialized during the privilegedConnect() call

        BufferedOutputStream out = new BufferedOutputStream(cmdOut, 512);

        InputStream in = cmdIn;

        if (useV4) {

            // SOCKS Protocol version 4 doesn't know how to deal with

            // DOMAIN type of addresses (unresolved addresses here)

            if (epoint.isUnresolved())

                throw new UnknownHostException(epoint.toString());

            connectV4(in, out, epoint, deadlineMillis);

            return;

        }

        // This is SOCKS V5

        out.write(PROTO_VERS);

        out.write(2);

        out.write(NO_AUTH);

        out.write(USER_PASSW);

        out.flush();

        byte[] data = new byte[2];

        int i = readSocksReply(in, data, deadlineMillis);

        if (i != 2 || ((int)data[0]) != PROTO_VERS) {

            // Maybe it's not a V5 sever after all

            // Let's try V4 before we give up

            // SOCKS Protocol version 4 doesn't know how to deal with

            // DOMAIN type of addresses (unresolved addresses here)

            if (epoint.isUnresolved())

                throw new UnknownHostException(epoint.toString());

            connectV4(in, out, epoint, deadlineMillis);

            return;

        }

        if (((int)data[1]) == NO_METHODS)

            throw new SocketException("SOCKS : No acceptable methods");

        if (!authenticate(data[1], in, out, deadlineMillis)) {

            throw new SocketException("SOCKS : authentication failed");

        }

        out.write(PROTO_VERS);

        out.write(CONNECT);

        out.write(0);

        /* Test for IPV4/IPV6/Unresolved */

        if (epoint.isUnresolved()) {

            out.write(DOMAIN_NAME);

            out.write(epoint.getHostName().length());

            try {

                out.write(epoint.getHostName().getBytes("ISO-8859-1"));

            } catch (java.io.UnsupportedEncodingException uee) {

                assert false;

            }

            out.write((epoint.getPort() >> 8) & 0xff);

            out.write((epoint.getPort() >> 0) & 0xff);

        } else if (epoint.getAddress() instanceof Inet6Address) {

            out.write(IPV6);

            out.write(epoint.getAddress().getAddress());

            out.write((epoint.getPort() >> 8) & 0xff);

            out.write((epoint.getPort() >> 0) & 0xff);

        } else {

            out.write(IPV4);

            out.write(epoint.getAddress().getAddress());

            out.write((epoint.getPort() >> 8) & 0xff);

            out.write((epoint.getPort() >> 0) & 0xff);

        }

        out.flush();

        data = new byte[4];

        i = readSocksReply(in, data, deadlineMillis);

        if (i != 4)

            throw new SocketException("Reply from SOCKS server has bad length");

        SocketException ex = null;

        int len;

        byte[] addr;

        switch (data[1]) {

        case REQUEST_OK:

            // success!

            switch(data[3]) {

            case IPV4:

                addr = new byte[4];

                i = readSocksReply(in, addr, deadlineMillis);

                if (i != 4)

                    throw new SocketException("Reply from SOCKS server badly formatted");

                data = new byte[2];

                i = readSocksReply(in, data, deadlineMillis);

                if (i != 2)

                    throw new SocketException("Reply from SOCKS server badly formatted");

                break;

            case DOMAIN_NAME:

                byte[] lenByte = new byte[1];

                i = readSocksReply(in, lenByte, deadlineMillis);

                if (i != 1)

                    throw new SocketException("Reply from SOCKS server badly formatted");

                len = lenByte[0] & 0xFF;

                byte[] host = new byte[len];

                i = readSocksReply(in, host, deadlineMillis);

                if (i != len)

                    throw new SocketException("Reply from SOCKS server badly formatted");

                data = new byte[2];

                i = readSocksReply(in, data, deadlineMillis);

                if (i != 2)

                    throw new SocketException("Reply from SOCKS server badly formatted");

                break;

            case IPV6:

                len = 16;

                addr = new byte[len];

                i = readSocksReply(in, addr, deadlineMillis);

                if (i != len)

                    throw new SocketException("Reply from SOCKS server badly formatted");

                data = new byte[2];

                i = readSocksReply(in, data, deadlineMillis);

                if (i != 2)

                    throw new SocketException("Reply from SOCKS server badly formatted");

                break;

            default:

                ex = new SocketException("Reply from SOCKS server contains wrong code");

                break;

            }

            break;

        case GENERAL_FAILURE:

            ex = new SocketException("SOCKS server general failure");

            break;

        case NOT_ALLOWED:

            ex = new SocketException("SOCKS: Connection not allowed by ruleset");

            break;

        case NET_UNREACHABLE:

            ex = new SocketException("SOCKS: Network unreachable");

            break;

        case HOST_UNREACHABLE: