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* JBoss, Home of Professional Open Source.
* Copyright 2014 Red Hat, Inc., and individual contributors
* as indicated by the @author tags.
*
* 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 io.undertow.websockets.extensions;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import java.util.zip.Deflater;
import io.undertow.websockets.WebSocketExtension;
import io.undertow.websockets.core.WebSocketLogger;
/**
* Implementation of {@code permessage-deflate} WebSocket Extension handshake.
* <p>
* This implementation supports parameters: {@code server_no_context_takeover, client_no_context_takeover} .
* <p>
* This implementation does not support parameters: {@code server_max_window_bits, client_max_window_bits} .
*
* @see <a href="http://tools.ietf.org/html/draft-ietf-hybi-permessage-compression-18">Compression Extensions for WebSocket</a>
*
* @author Lucas Ponce
*/
public class PerMessageDeflateHandshake implements ExtensionHandshake {
private static final String PERMESSAGE_DEFLATE = "permessage-deflate";
private static final String SERVER_NO_CONTEXT_TAKEOVER = "server_no_context_takeover";
private static final String CLIENT_NO_CONTEXT_TAKEOVER = "client_no_context_takeover";
private static final String SERVER_MAX_WINDOW_BITS = "server_max_window_bits";
private static final String CLIENT_MAX_WINDOW_BITS = "client_max_window_bits";
private final Set<String> incompatibleExtensions = new HashSet<>();
private boolean compressContextTakeover;
private boolean decompressContextTakeover;
private final boolean client;
private final int deflaterLevel;
/**
* Default configuration for DEFLATE algorithm implementation
*/
public static final int DEFAULT_DEFLATER = Deflater.DEFAULT_COMPRESSION;
public PerMessageDeflateHandshake() {
this(false);
}
/**
* Create a new {@code PerMessageDeflateHandshake} instance.
*
* @param client indicate if extension is configured in client ({@code true }) context or server ({@code false }) context.
*/
public PerMessageDeflateHandshake(final boolean client) {
this(client, DEFAULT_DEFLATER);
}
/**
* Create a new {@code PerMessageDeflateHandshake} instance.
*
* @param client indicate if extension is configured in client ({@code true }) context or server ({@code false }) context
* @param deflaterLevel the level of configuration of DEFLATE algorithm implementation
*/
public PerMessageDeflateHandshake(final boolean client, final int deflaterLevel) {
this(client, deflaterLevel, true, true);
}
/**
* Create a new {@code PerMessageDeflateHandshake} instance.
*
* @param client flag for client ({@code true }) context or server ({@code false }) context
* @param compressContextTakeover flag for compressor context takeover or without compressor context
* @param decompressContextTakeover flag for decompressor context takeover or without decompressor context
*/
public PerMessageDeflateHandshake(final boolean client, boolean compressContextTakeover, boolean decompressContextTakeover) {
this(client, DEFAULT_DEFLATER, compressContextTakeover, decompressContextTakeover);
}
/**
* Create a new {@code PerMessageDeflateHandshake} instance.
*
* @param client flag for client ({@code true }) context or server ({@code false }) context
* @param deflaterLevel the level of configuration of DEFLATE algorithm implementation
* @param compressContextTakeover flag for compressor context takeover or without compressor context
* @param decompressContextTakeover flag for decompressor context takeover or without decompressor context
*/
public PerMessageDeflateHandshake(final boolean client, final int deflaterLevel, boolean compressContextTakeover, boolean decompressContextTakeover) {
this.client = client;
this.deflaterLevel = deflaterLevel;
/*
This extension is incompatible with multiple instances of same extension in the same Endpoint.
*/
incompatibleExtensions.add(PERMESSAGE_DEFLATE);
this.compressContextTakeover = compressContextTakeover;
this.decompressContextTakeover = decompressContextTakeover;
}
@Override
public String getName() {
return PERMESSAGE_DEFLATE;
}
@Override
public WebSocketExtension accept(final WebSocketExtension extension) {
if (extension == null || !extension.getName().equals(getName())) return null;
WebSocketExtension negotiated = new WebSocketExtension(extension.getName());
if (extension.getParameters() == null || extension.getParameters().size() == 0) return negotiated;
for (WebSocketExtension.Parameter parameter : extension.getParameters()) {
if (parameter.getName().equals(SERVER_MAX_WINDOW_BITS)) {
/*
Not supported
*/
} else if (parameter.getName().equals(CLIENT_MAX_WINDOW_BITS)) {
/*
Not supported
*/
} else if (parameter.getName().equals(SERVER_NO_CONTEXT_TAKEOVER)) {
negotiated.getParameters().add(parameter);
if (client) {
decompressContextTakeover = false;
} else {
compressContextTakeover = false;
}
} else if (parameter.getName().equals(CLIENT_NO_CONTEXT_TAKEOVER)) {
negotiated.getParameters().add(parameter);
if (client) {
compressContextTakeover = false;
} else {
decompressContextTakeover = false;
}
} else {
WebSocketLogger.EXTENSION_LOGGER.incorrectExtensionParameter(parameter);
return null;
}
}
WebSocketLogger.EXTENSION_LOGGER.debugf("Negotiated extension %s for handshake %s", negotiated, extension);
return negotiated;
}
@Override
public boolean isIncompatible(List<ExtensionHandshake> extensions) {
for (ExtensionHandshake extension : extensions) {
if (incompatibleExtensions.contains(extension.getName())) {
return true;
}
}
return false;
}
@Override
public ExtensionFunction create() {
return new PerMessageDeflateFunction(deflaterLevel, compressContextTakeover, decompressContextTakeover);
}
}