001/** 002 * 003 * Copyright 2013 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 023public abstract class XMPPInputOutputStream { 024 025 protected static FlushMethod flushMethod; 026 027 /** 028 * Set the used flushed method when compressing data. The default is full flush which may not 029 * achieve the best compression ratio, but provides better security against certain attacks. 030 * Only use sync flush if you fully understand the implications. 031 * 032 * @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> 033 * @param flushMethod 034 */ 035 public static void setFlushMethod(FlushMethod flushMethod) { 036 XMPPInputOutputStream.flushMethod = flushMethod; 037 } 038 039 protected final String compressionMethod; 040 041 protected XMPPInputOutputStream(String compressionMethod) { 042 this.compressionMethod = compressionMethod; 043 } 044 045 public String getCompressionMethod() { 046 return compressionMethod; 047 } 048 049 public abstract boolean isSupported(); 050 051 public abstract InputStream getInputStream(InputStream inputStream) throws IOException; 052 053 public abstract OutputStream getOutputStream(OutputStream outputStream) throws IOException; 054 055 public enum FlushMethod { 056 FULL_FLUSH, 057 SYNC_FLUSH, 058 } 059}