ZlibCompression.java

/*
 * Copyright (C)2009 - SSHJ Contributors
 *
 * 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.
 */
package net.schmizz.sshj.transport.compression;

import com.jcraft.jzlib.JZlib;
import com.jcraft.jzlib.ZStream;
import net.schmizz.sshj.common.Buffer;
import net.schmizz.sshj.common.DisconnectReason;
import net.schmizz.sshj.common.SSHRuntimeException;
import net.schmizz.sshj.transport.TransportException;

/** ZLib based Compression. */
public class ZlibCompression
        implements Compression {

    /** Named factory for the ZLib Compression. */
    public static class Factory
            implements net.schmizz.sshj.common.Factory.Named<Compression> {

        @Override
        public Compression create() {
            return new ZlibCompression();
        }

        @Override
        public String getName() {
            return "zlib";
        }
    }

    private static final int BUF_SIZE = 4096;

    private final byte[] tempBuf = new byte[BUF_SIZE];

    private ZStream stream;

    @Override
    public void init(Mode mode) {
        stream = new ZStream();
        switch (mode) {
            case DEFLATE:
                stream.deflateInit(JZlib.Z_DEFAULT_COMPRESSION);
                break;
            case INFLATE:
                stream.inflateInit();
                break;
            default:
                assert false;
        }
    }

    @Override
    public boolean isDelayed() {
        return false;
    }

    @Override
    public void compress(Buffer buffer) {
        stream.next_in = buffer.array();
        stream.next_in_index = buffer.rpos();
        stream.avail_in = buffer.available();
        buffer.wpos(buffer.rpos());
        do {
            stream.next_out = tempBuf;
            stream.next_out_index = 0;
            stream.avail_out = BUF_SIZE;
            final int status = stream.deflate(JZlib.Z_PARTIAL_FLUSH);
            if (status == JZlib.Z_OK) {
                buffer.putRawBytes(tempBuf, 0, BUF_SIZE - stream.avail_out);
            } else {
                throw new SSHRuntimeException("compress: deflate returned " + status);
            }
        } while (stream.avail_out == 0);
    }


    @Override
    public void uncompress(Buffer from, Buffer to)
            throws TransportException {
        stream.next_in = from.array();
        stream.next_in_index = from.rpos();
        stream.avail_in = from.available();
        while (true) {
            stream.next_out = tempBuf;
            stream.next_out_index = 0;
            stream.avail_out = BUF_SIZE;
            final int status = stream.inflate(JZlib.Z_PARTIAL_FLUSH);
            switch (status) {
                case JZlib.Z_OK:
                    to.putRawBytes(tempBuf, 0, BUF_SIZE - stream.avail_out);
                    break;
                case JZlib.Z_BUF_ERROR:
                    return;
                default:
                    throw new TransportException(DisconnectReason.COMPRESSION_ERROR, "uncompress: inflate returned "
                            + status);
            }
        }
    }

}