001/**
002 *
003 * Copyright 2013-2020 Florian Schmaus
004 *
005 * Licensed under the Apache License, Version 2.0 (the "License");
006 * you may not use this file except in compliance with the License.
007 * You may obtain a copy of the License at
008 *
009 *     http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.jivesoftware.smack.compression;
018
019import java.io.IOException;
020import java.io.InputStream;
021import java.io.OutputStream;
022
023import org.jivesoftware.smack.util.Objects;
024
025public abstract class XMPPInputOutputStream {
026
027    protected static FlushMethod flushMethod = FlushMethod.SYNC_FLUSH;
028
029    /**
030     * Set the used flushed method when compressing data. The default is full flush which may not
031     * achieve the best compression ratio, but provides better security against certain attacks.
032     * Only use sync flush if you fully understand the implications.
033     *
034     * @see <a href="https://blog.thijsalkema.de/blog/2014/08/07/https-attacks-and-xmpp-2-crime-and-breach/">Attacks against XMPP when using compression</a>
035     * @param flushMethod TODO javadoc me please
036     */
037    public static void setFlushMethod(FlushMethod flushMethod) {
038        XMPPInputOutputStream.flushMethod = Objects.requireNonNull(flushMethod);
039    }
040
041    public static FlushMethod getFlushMethod() {
042        return flushMethod;
043    }
044
045    protected final String compressionMethod;
046
047    protected XMPPInputOutputStream(String compressionMethod) {
048        this.compressionMethod = compressionMethod;
049    }
050
051    public String getCompressionMethod() {
052        return compressionMethod;
053    }
054
055    public abstract boolean isSupported();
056
057    public abstract InputStream getInputStream(InputStream inputStream) throws IOException;
058
059    public abstract OutputStream getOutputStream(OutputStream outputStream) throws IOException;
060
061    public enum FlushMethod {
062        FULL_FLUSH,
063        SYNC_FLUSH,
064    }
065}