/*
* 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 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 io.netty.handler.codec.http.websocketx.extensions.WebSocketServerExtension;
import io.netty.handler.codec.http.websocketx.extensions.WebSocketServerExtensionHandshaker;
import java.util.Collections;
/**
* <a href="https://tools.ietf.org/id/draft-tyoshino-hybi-websocket-perframe-deflate-06.txt">perframe-deflate</a>
* handshake implementation.
*/
public final class DeflateFrameServerExtensionHandshaker implements WebSocketServerExtensionHandshaker {
static final String X_WEBKIT_DEFLATE_FRAME_EXTENSION = "x-webkit-deflate-frame";
static final String DEFLATE_FRAME_EXTENSION = "deflate-frame";
private final int compressionLevel;
/**
* Constructor with default configuration.
*/
public DeflateFrameServerExtensionHandshaker() {
this(6);
}
/**
* Constructor with custom configuration.
*
* @param compressionLevel
* Compression level between 0 and 9 (default is 6).
*/
public DeflateFrameServerExtensionHandshaker(int compressionLevel) {
if (compressionLevel < 0 || compressionLevel > 9) {
throw new IllegalArgumentException(
"compressionLevel: " + compressionLevel + " (expected: 0-9)");
}
this.compressionLevel = compressionLevel;
}
@Override
public WebSocketServerExtension handshakeExtension(WebSocketExtensionData extensionData) {
if (!X_WEBKIT_DEFLATE_FRAME_EXTENSION.equals(extensionData.name()) &&
!DEFLATE_FRAME_EXTENSION.equals(extensionData.name())) {
return null;
}
if (extensionData.parameters().isEmpty()) {
return new DeflateFrameServerExtension(compressionLevel, extensionData.name());
} else {
return null;
}
}
private static class DeflateFrameServerExtension implements WebSocketServerExtension {
private final String extensionName;
private final int compressionLevel;
public DeflateFrameServerExtension(int compressionLevel, String extensionName) {
this.extensionName = extensionName;
this.compressionLevel = compressionLevel;
}
@Override
public int rsv() {
return RSV1;
}
@Override
public WebSocketExtensionEncoder newExtensionEncoder() {
return new PerFrameDeflateEncoder(compressionLevel, 15, false);
}
@Override
public WebSocketExtensionDecoder newExtensionDecoder() {
return new PerFrameDeflateDecoder(false);
}
@Override
public WebSocketExtensionData newReponseData() {
return new WebSocketExtensionData(extensionName, Collections.<String, String>emptyMap());
}
}
}