ChannelOutputStream.java

/*
 * Copyright 2010 netling project <http://netling.org>
 *
 * 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.
 *
 * This file may incorporate work covered by the following copyright and
 * permission notice:
 *
 *     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.
 */
package org.netling.ssh.connection.channel;

import java.io.IOException;
import java.io.OutputStream;

import org.netling.ssh.common.ErrorNotifiable;
import org.netling.ssh.common.Message;
import org.netling.ssh.common.SSHException;
import org.netling.ssh.common.SSHPacket;
import org.netling.ssh.connection.ConnectionException;
import org.netling.ssh.transport.Transport;

/**
 * {@link OutputStream} for channels. Buffers data upto the remote window's maximum packet size. Data can also be
 * flushed via {@link #flush()} and is also flushed on {@link #close()}.
 */
public final class ChannelOutputStream
        extends OutputStream
        implements ErrorNotifiable {

    private final Channel chan;
    private final Transport trans;
    private final Window.Remote win;
    private final SSHPacket buffer = new SSHPacket();
    private final byte[] b = new byte[1];
    private int bufferLength;
    private boolean closed;
    private SSHException error;

    public ChannelOutputStream(Channel chan, Transport trans, Window.Remote win) {
        this.chan = chan;
        this.trans = trans;
        this.win = win;
        prepBuffer();
    }

    private void prepBuffer() {
        bufferLength = 0;
        buffer.rpos(5);
        buffer.wpos(5);
        buffer.putMessageID(Message.CHANNEL_DATA);
        buffer.putInt(0); // meant to be recipient
        buffer.putInt(0); // meant to be data length
    }

    @Override
    public synchronized void write(int w)
            throws IOException {
        b[0] = (byte) w;
        write(b, 0, 1);
    }

    @Override
    public synchronized void write(byte[] data, int off, int len)
            throws IOException {
        checkClose();
        while (len > 0) {
            final int x = Math.min(len, win.getMaxPacketSize() - bufferLength);
            if (x <= 0) {
                flush();
                continue;
            }
            buffer.putRawBytes(data, off, x);
            bufferLength += x;
            off += x;
            len -= x;
        }
    }

    @Override
    public synchronized void notifyError(SSHException error) {
        this.error = error;
    }

    private synchronized void checkClose()
            throws SSHException {
        if (closed)
            if (error != null)
                throw error;
            else
                throw new ConnectionException("Stream closed");
    }

    @Override
    public synchronized void close()
            throws IOException {
        if (!closed)
            try {
                flush();
                chan.sendEOF();
            } finally {
                setClosed();
            }
    }

    public synchronized void setClosed() {
        closed = true;
    }

    @Override
    public synchronized void flush()
            throws IOException {
        checkClose();

        if (bufferLength <= 0) // No data to send
            return;

        putRecipientAndLength();

        try {
            win.waitAndConsume(bufferLength);
            trans.write(buffer);
        } finally {
            prepBuffer();
        }
    }

    private void putRecipientAndLength() {
        final int origPos = buffer.wpos();
        buffer.wpos(6);
        buffer.putInt(chan.getRecipient());
        buffer.putInt(bufferLength);
        buffer.wpos(origPos);
    }

    @Override
    public String toString() {
        return "< ChannelOutputStream for Channel #" + chan.getID() + " >";
    }

}