package com.trilead.ssh2.packets;

import java.io.IOException;

/**
 * PacketOpenSessionChannel.
 *
 * @author Christian Plattner, plattner@trilead.com
 * @version $Id: PacketOpenSessionChannel.java,v 1.1 2007/10/15 12:49:55 cplattne Exp $
 */
public class PacketOpenSessionChannel {
    byte[] payload;

    int channelID;
    int initialWindowSize;
    int maxPacketSize;

    public PacketOpenSessionChannel(int channelID, int initialWindowSize,
                                    int maxPacketSize) {
        this.channelID = channelID;
        this.initialWindowSize = initialWindowSize;
        this.maxPacketSize = maxPacketSize;
    }

    public PacketOpenSessionChannel(byte payload[], int off, int len) throws IOException {
        this.payload = new byte[len];
        System.arraycopy(payload, off, this.payload, 0, len);
        TypesReader tr = new TypesReader(payload);
        int packet_type = tr.readByte();

        if (packet_type != Packets.SSH_MSG_CHANNEL_OPEN)
            throw new IOException("This is not a SSH_MSG_CHANNEL_OPEN! ("
                                  + packet_type + ")");

        channelID = tr.readUINT32();
        initialWindowSize = tr.readUINT32();
        maxPacketSize = tr.readUINT32();

        if (tr.remain() != 0)
            throw new IOException("Padding in SSH_MSG_CHANNEL_OPEN packet!");
    }

    public byte[] getPayload() {
        if (payload == null) {
            TypesWriter tw = new TypesWriter();
            tw.writeByte(Packets.SSH_MSG_CHANNEL_OPEN);
            tw.writeString("session");
            tw.writeUINT32(channelID);
            tw.writeUINT32(initialWindowSize);
            tw.writeUINT32(maxPacketSize);
            payload = tw.getBytes();
        }

        return payload;
    }
}