/*
* 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());
}
}
}