/*
 * @(#)SocketTransportService.java	1.28 03/12/19
 *
 * Copyright (c) 2004, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

package com.sun.tools.jdi;

import com.sun.jdi.*;
import com.sun.jdi.connect.*;
import com.sun.jdi.connect.spi.*;
import java.net.*;
import java.io.*;
import java.util.Map;
import java.util.ResourceBundle;

/*
 * A transport service based on a TCP connection between the 
 * debugger and debugee. 
 */

public class SocketTransportService extends TransportService {
    private ResourceBundle messages = null;

    /**
     * The listener returned by startListening encapsulates
     * the ServerSocket. 
     */
    static class SocketListenKey extends ListenKey {
	ServerSocket ss;

	SocketListenKey(ServerSocket ss) {
	    this.ss = ss;
	}

	ServerSocket socket() {
	    return ss;
	}

	/*
	 * Returns the string representation of the address that this
	 * listen key represents. 
	 */
	public String address() {
	    InetAddress address = ss.getInetAddress();

	    /*
	     * If bound to the wildcard address then use current local
	     * hostname. In the event that we don't know our own hostname
	     * then assume that host supports IPv4 and return something to
	     * represent the loopback address.
	     */
	    if (address.isAnyLocalAddress()) {
		try {
		    address = InetAddress.getLocalHost();
		} catch (UnknownHostException uhe) {
	 	    byte[] loopback = {0x7f,0x00,0x00,0x01};
		    try {
		        address = InetAddress.getByAddress("127.0.0.1", loopback);
		    } catch (UnknownHostException x) {
			throw new InternalError("unable to get local hostname");
		    }
		}
	    }

	    /*
 	     * Now decide if we return a hostname or IP address. Where possible
	     * return a hostname but in the case that we are bound to an
	     * address that isn't registered in the name service then we 
	     * return an address. 
	     */
	    String result;
	    String hostname = address.getHostName();
	    String hostaddr = address.getHostAddress();
	    if (hostname.equals(hostaddr)) {
		if (address instanceof Inet6Address) {		
		    result = "[" + hostaddr + "]";
		} else {
		    result = hostaddr;
		}
	    } else {
		result = hostname;
	    }

	    /*
	     * Finally return "hostname:port", "ipv4-address:port" or 
	     * "[ipv6-address]:port".
	     */
	    return result + ":" + ss.getLocalPort();
	}

	public String toString() {
	    return address();
	}
    }

    /**
     * Handshake with the debuggee
     */
    void handshake(Socket s, long timeout) throws IOException {
	s.setSoTimeout((int)timeout);

        byte[] hello = "JDWP-Handshake".getBytes("UTF-8");
        s.getOutputStream().write(hello);

        byte[] b = new byte[hello.length];
        int received = 0;
        while (received < hello.length) {
            int n;
            try {
                n = s.getInputStream().read(b, received, hello.length-received);
            } catch (SocketTimeoutException x) {
                throw new IOException("handshake timeout");
            }
            if (n < 0) {
                s.close();
                throw new IOException("handshake failed - connection prematurally closed");
            }
            received += n;
        }
        for (int i=0; i<hello.length; i++) {
            if (b[i] != hello[i]) {
                throw new IOException("handshake failed - unrecognized message from target VM");
            }
        }

	// disable read timeout
	s.setSoTimeout(0);
    }

    /**
     * No-arg constructor 
     */
    public SocketTransportService() {
    }

    /**
     * The name of this transport service
     */
    public String name() {
        return "Socket";
    }

    /**
     * Return localized description of this transport service
     */
    public String description() {
	synchronized (this) {
	    if (messages == null) {
                messages = ResourceBundle.getBundle("com.sun.tools.jdi.resources.jdi");
	    }
        }
        return messages.getString("socket_transportservice.description");
    }

    /**
     * Return the capabilities of this transport service
     */
    public Capabilities capabilities() {
        return new SocketTransportServiceCapabilities();
    }


    /**
     * Attach to the specified address with optional attach and handshake
     * timeout.
     */
    public Connection attach(String address, long attachTimeout, long handshakeTimeout) 
	throws IOException {

	if (address == null) {
            throw new NullPointerException("address is null");
        }
        if (attachTimeout < 0 || handshakeTimeout < 0) {
            throw new IllegalArgumentException("timeout is negative");
        }

        int splitIndex = address.indexOf(':');
	String host;
	String portStr;
        if (splitIndex < 0) {
	    host = InetAddress.getLocalHost().getHostName();
	    portStr = address;
	} else {
	    host = address.substring(0, splitIndex);
	    portStr = address.substring(splitIndex+1);
	}

	int port;
	try {
            port = Integer.decode(portStr).intValue();
        } catch (NumberFormatException e) {
            throw new IllegalArgumentException(
                "unable to parse port number in address");
        }


	// open TCP connection to VM 

	InetSocketAddress sa = new InetSocketAddress(host, port);
	Socket s = new Socket();
	try {
	    s.connect(sa, (int)attachTimeout);
	} catch (SocketTimeoutException exc) {
	    try {
		s.close();
	    } catch (IOException x) { }
	    throw new TransportTimeoutException("timed out trying to establish connection");
	}

	// handshake with the target VM
  	try {
	    handshake(s, handshakeTimeout);
	} catch (IOException exc) {
	    try {
		s.close();
	    } catch (IOException x) { }
	    throw exc;
 	}

        return new SocketConnection(s);
    }

    /*
     * Listen on the specified address and port. Return a listener
     * that encapsulates the ServerSocket.
     */
    ListenKey startListening(String localaddress, int port) throws IOException {
        InetSocketAddress sa;
        if (localaddress == null) {
            sa = new InetSocketAddress(port);
        } else {
            sa = new InetSocketAddress(localaddress, port);
        }
        ServerSocket ss = new ServerSocket();
        ss.bind(sa);
        return new SocketListenKey(ss);
    }

    /**
     * Listen on the specified address
     */
    public ListenKey startListening(String address) throws IOException {
	// use ephemeral port if address isn't specified.
        if (address == null || address.length() == 0) {
	    address = "0";
        }

        int splitIndex = address.indexOf(':');
	String localaddr = null;
        if (splitIndex >= 0) {
            localaddr = address.substring(0, splitIndex);
	    address = address.substring(splitIndex+1);
	}

	int port;
        try {
	    port = Integer.decode(address).intValue();
        } catch (NumberFormatException e) {
            throw new IllegalArgumentException(
                    "unable to parse port number in address");
        }

        return startListening(localaddr, port);
    }

    /**
     * Listen on the default address
     */
    public ListenKey startListening() throws IOException {
        return startListening(null, 0);
    }

    /**
     * Stop the listener
     */
    public void stopListening(ListenKey listener) throws IOException {
	if (!(listener instanceof SocketListenKey)) {
	    throw new IllegalArgumentException("Invalid listener");
	}

	synchronized (listener) {
            ServerSocket ss = ((SocketListenKey)listener).socket();
	
  	    // if the ServerSocket has been closed it means
	    // the listener is invalid
	    if (ss.isClosed()) {
	        throw new IllegalArgumentException("Invalid listener");
	    }
            ss.close();
	}
    }

    /**
     * Accept a connection from a debuggee and handshake with it.
     */
    public Connection accept(ListenKey listener, long acceptTimeout, long handshakeTimeout) throws IOException {
	if (acceptTimeout < 0 || handshakeTimeout < 0) {
	    throw new IllegalArgumentException("timeout is negative");
	}
	if (!(listener instanceof SocketListenKey)) {
            throw new IllegalArgumentException("Invalid listener");
        }
        ServerSocket ss;

	// obtain the ServerSocket from the listener - if the
	// socket is closed it means the listener is invalid
	synchronized (listener) {
	    ss = ((SocketListenKey)listener).socket();
	    if (ss.isClosed()) {
               throw new IllegalArgumentException("Invalid listener");
	    }
        }

	// from here onwards it's possible that the ServerSocket
	// may be closed by a call to stopListening - that's okay
	// because the ServerSocket methods will throw an
	// IOException indicating the socket is closed.
	//
	// Additionally, it's possible that another thread calls accept
	// with a different accept timeout - that creates a same race
	// condition between setting the timeout and calling accept.
	// As it is such an unlikely scenario (requires both threads
	// to be using the same listener we've chosen to ignore the issue).

	ss.setSoTimeout((int)acceptTimeout);
	Socket s;
	try {
	    s = ss.accept();
	} catch (SocketTimeoutException x) {
	    throw new TransportTimeoutException("timeout waiting for connection");
	}

	// handshake here
	handshake(s, handshakeTimeout);

        return new SocketConnection(s);
    }

    public String toString() {
       return name();
    }
}


/*
 * The Connection returned by attach and accept is one of these
 */
class SocketConnection extends Connection {
    private Socket socket;
    private boolean closed = false;
    private OutputStream socketOutput;
    private InputStream socketInput;
    private Object receiveLock = new Object();
    private Object sendLock = new Object();
    private Object closeLock = new Object();

    SocketConnection(Socket socket) throws IOException {
        this.socket = socket;
        socket.setTcpNoDelay(true);
        socketInput = socket.getInputStream();
        socketOutput = socket.getOutputStream();
    }

    public void close() throws IOException {
	synchronized (closeLock) {
	   if (closed) {
	        return;
	   }
           socketOutput.close();
           socketInput.close();
           socket.close();
	   closed = true;
	}
    }

    public boolean isOpen() {
	synchronized (closeLock) {
	    return !closed;
	}
    }

    public byte[] readPacket() throws IOException {
	if (!isOpen()) {
	    throw new ClosedConnectionException("connection is closed");
	}
        synchronized (receiveLock) {
            int b1,b2,b3,b4;
    
            // length
	    try {
                b1 = socketInput.read();
                b2 = socketInput.read();
                b3 = socketInput.read();
                b4 = socketInput.read();
	    } catch (IOException ioe) {
		if (!isOpen()) {
		    throw new ClosedConnectionException("connection is closed");
		} else {
		    throw ioe;
		}
	    }
  
	    // EOF 
            if (b1<0) {
	       return new byte[0];
	    }

	    if (b2<0 || b3<0 || b4<0) {
		throw new IOException("protocol error - premature EOF");
	    }

            int len = ((b1 << 24) | (b2 << 16) | (b3 << 8) | (b4 << 0));

	    if (len < 0) {
		throw new IOException("protocol error - invalid length");
	    }

	    byte b[] = new byte[len];
	    b[0] = (byte)b1;
	    b[1] = (byte)b2;
	    b[2] = (byte)b3;
	    b[3] = (byte)b4;

	    int off = 4;
	    len -= off;

	    while (len > 0) {
		int count;
		try { 
		    count = socketInput.read(b, off, len);
		} catch (IOException ioe) {
		    if (!isOpen()) {
			throw new ClosedConnectionException("connection is closed");
		    } else {
			throw ioe;
		    }
		}
                if (count < 0) {
		    throw new IOException("protocol error - premature EOF");
                }
		len -= count;
		off += count;
            }

	    return b;
        }
    }

    public void writePacket(byte b[]) throws IOException {
	if (!isOpen()) {
            throw new ClosedConnectionException("connection is closed");
        }

	/*
	 * Check the packet size
	 */
        if (b.length < 11) {
            throw new IllegalArgumentException("packet is insufficient size");
        }
        int b0 = b[0] & 0xff;
        int b1 = b[1] & 0xff;
        int b2 = b[2] & 0xff;
        int b3 = b[3] & 0xff;
        int len = ((b0 << 24) | (b1 << 16) | (b2 << 8) | (b3 << 0));
	if (len < 11) {
            throw new IllegalArgumentException("packet is insufficient size");
        }

	/*
	 * Check that the byte array contains the complete packet
	 */
        if (len > b.length) {
            throw new IllegalArgumentException("length mis-match");
        }

        synchronized (sendLock) {
	    try {
		/*
	 	 * Send the packet (ignoring any bytes that follow
		 * the packet in the byte array).
	 	 */
	        socketOutput.write(b, 0, len);
	    } catch (IOException ioe) {
		if (!isOpen()) {
                    throw new ClosedConnectionException("connection is closed");
                } else {   
                    throw ioe;
                }  
	    }
        }
    }
}


/*
 * The capabilities of the socket transport service 
 */
class SocketTransportServiceCapabilities extends TransportService.Capabilities {

    public boolean supportsMultipleConnections() {
	return true;
    }

    public boolean supportsAttachTimeout() {
	return true;
    }

    public boolean supportsAcceptTimeout() {
	return true;
    }

    public boolean supportsHandshakeTimeout() {
	return true;
    }

}