/*
* Copyright 2014 The Netty Project
*
* The Netty Project licenses this file to you 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.netty.handler.codec.http.websocketx.extensions.compression;
import static io.netty.handler.codec.http.websocketx.extensions.compression.
PerMessageDeflateServerExtensionHandshaker.*;
import io.netty.handler.codec.compression.ZlibCodecFactory;
import io.netty.handler.codec.http.websocketx.extensions.WebSocketClientExtension;
import io.netty.handler.codec.http.websocketx.extensions.WebSocketClientExtensionHandshaker;
import io.netty.handler.codec.http.websocketx.extensions.WebSocketExtensionData;
import io.netty.handler.codec.http.websocketx.extensions.WebSocketExtensionDecoder;
import io.netty.handler.codec.http.websocketx.extensions.WebSocketExtensionEncoder;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map.Entry;
/**
* <a href="http://tools.ietf.org/html/draft-ietf-hybi-permessage-compression-18">permessage-deflate</a>
* handshake implementation.
*/
public final class PerMessageDeflateClientExtensionHandshaker implements WebSocketClientExtensionHandshaker {
private final int compressionLevel;
private final boolean allowClientWindowSize;
private final int requestedServerWindowSize;
private final boolean allowClientNoContext;
private final boolean requestedServerNoContext;
/**
* Constructor with default configuration.
*/
public PerMessageDeflateClientExtensionHandshaker() {
this(6, ZlibCodecFactory.isSupportingWindowSizeAndMemLevel(), MAX_WINDOW_SIZE, false, false);
}
/**
* Constructor with custom configuration.
*
* @param compressionLevel
* Compression level between 0 and 9 (default is 6).
* @param allowClientWindowSize
* allows WebSocket server to customize the client inflater window size
* (default is false).
* @param requestedServerWindowSize
* indicates the requested sever window size to use if server inflater is customizable.
* @param allowClientNoContext
* allows WebSocket server to activate client_no_context_takeover
* (default is false).
* @param requestedServerNoContext
* indicates if client needs to activate server_no_context_takeover
* if server is compatible with (default is false).
*/
public PerMessageDeflateClientExtensionHandshaker(int compressionLevel,
boolean allowClientWindowSize, int requestedServerWindowSize,
boolean allowClientNoContext, boolean requestedServerNoContext) {
if (requestedServerWindowSize > MAX_WINDOW_SIZE || requestedServerWindowSize < MIN_WINDOW_SIZE) {
throw new IllegalArgumentException(
"requestedServerWindowSize: " + requestedServerWindowSize + " (expected: 8-15)");
}
if (compressionLevel < 0 || compressionLevel > 9) {
throw new IllegalArgumentException(
"compressionLevel: " + compressionLevel + " (expected: 0-9)");
}
this.compressionLevel = compressionLevel;
this.allowClientWindowSize = allowClientWindowSize;
this.requestedServerWindowSize = requestedServerWindowSize;
this.allowClientNoContext = allowClientNoContext;
this.requestedServerNoContext = requestedServerNoContext;
}
@Override
public WebSocketExtensionData newRequestData() {
HashMap<String, String> parameters = new HashMap<String, String>(4);
if (requestedServerWindowSize != MAX_WINDOW_SIZE) {
parameters.put(SERVER_NO_CONTEXT, null);
}
if (allowClientNoContext) {
parameters.put(CLIENT_NO_CONTEXT, null);
}
if (requestedServerWindowSize != MAX_WINDOW_SIZE) {
parameters.put(SERVER_MAX_WINDOW, Integer.toString(requestedServerWindowSize));
}
if (allowClientWindowSize) {
parameters.put(CLIENT_MAX_WINDOW, null);
}
return new WebSocketExtensionData(PERMESSAGE_DEFLATE_EXTENSION, parameters);
}
@Override
public WebSocketClientExtension handshakeExtension(WebSocketExtensionData extensionData) {
if (!PERMESSAGE_DEFLATE_EXTENSION.equals(extensionData.name())) {
return null;
}
boolean succeed = true;
int clientWindowSize = MAX_WINDOW_SIZE;
int serverWindowSize = MAX_WINDOW_SIZE;
boolean serverNoContext = false;
boolean clientNoContext = false;
Iterator<Entry<String, String>> parametersIterator =
extensionData.parameters().entrySet().iterator();
while (succeed && parametersIterator.hasNext()) {
Entry<String, String> parameter = parametersIterator.next();
if (CLIENT_MAX_WINDOW.equalsIgnoreCase(parameter.getKey())) {
// allowed client_window_size_bits
if (allowClientWindowSize) {
clientWindowSize = Integer.parseInt(parameter.getValue());
} else {
succeed = false;
}
} else if (SERVER_MAX_WINDOW.equalsIgnoreCase(parameter.getKey())) {
// acknowledged server_window_size_bits
serverWindowSize = Integer.parseInt(parameter.getValue());
if (clientWindowSize > MAX_WINDOW_SIZE || clientWindowSize < MIN_WINDOW_SIZE) {
succeed = false;
}
} else if (CLIENT_NO_CONTEXT.equalsIgnoreCase(parameter.getKey())) {
// allowed client_no_context_takeover
if (allowClientNoContext) {
clientNoContext = true;
} else {
succeed = false;
}
} else if (SERVER_NO_CONTEXT.equalsIgnoreCase(parameter.getKey())) {
// acknowledged server_no_context_takeover
if (requestedServerNoContext) {
serverNoContext = true;
} else {
succeed = false;
}
} else {
// unknown parameter
succeed = false;
}
}
if ((requestedServerNoContext && !serverNoContext) ||
requestedServerWindowSize != serverWindowSize) {
succeed = false;
}
if (succeed) {
return new PermessageDeflateExtension(serverNoContext, serverWindowSize,
clientNoContext, clientWindowSize);
} else {
return null;
}
}
private final class PermessageDeflateExtension implements WebSocketClientExtension {
private final boolean serverNoContext;
private final int serverWindowSize;
private final boolean clientNoContext;
private final int clientWindowSize;
@Override
public int rsv() {
return RSV1;
}
public PermessageDeflateExtension(boolean serverNoContext, int serverWindowSize,
boolean clientNoContext, int clientWindowSize) {
this.serverNoContext = serverNoContext;
this.serverWindowSize = serverWindowSize;
this.clientNoContext = clientNoContext;
this.clientWindowSize = clientWindowSize;
}
@Override
public WebSocketExtensionEncoder newExtensionEncoder() {
return new PerMessageDeflateEncoder(compressionLevel, serverWindowSize, serverNoContext);
}
@Override
public WebSocketExtensionDecoder newExtensionDecoder() {
return new PerMessageDeflateDecoder(clientNoContext);
}
}
}