/*
* 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.compression.
ZlibCodecFactory;
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.
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
PerMessageDeflateServerExtensionHandshaker implements
WebSocketServerExtensionHandshaker {
public static final int
MIN_WINDOW_SIZE = 8;
public static final int
MAX_WINDOW_SIZE = 15;
static final
String PERMESSAGE_DEFLATE_EXTENSION = "permessage-deflate";
static final
String CLIENT_MAX_WINDOW = "client_max_window_bits";
static final
String SERVER_MAX_WINDOW = "server_max_window_bits";
static final
String CLIENT_NO_CONTEXT = "client_no_context_takeover";
static final
String SERVER_NO_CONTEXT = "server_no_context_takeover";
private final int
compressionLevel;
private final boolean
allowServerWindowSize;
private final int
preferredClientWindowSize;
private final boolean
allowServerNoContext;
private final boolean
preferredClientNoContext;
/**
* Constructor with default configuration.
*/
public
PerMessageDeflateServerExtensionHandshaker() {
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 allowServerWindowSize
* allows WebSocket client to customize the server inflater window size
* (default is false).
* @param preferredClientWindowSize
* indicates the preferred client window size to use if client inflater is customizable.
* @param allowServerNoContext
* allows WebSocket client to activate server_no_context_takeover
* (default is false).
* @param preferredClientNoContext
* indicates if server prefers to activate client_no_context_takeover
* if client is compatible with (default is false).
*/
public
PerMessageDeflateServerExtensionHandshaker(int
compressionLevel,
boolean
allowServerWindowSize, int
preferredClientWindowSize,
boolean
allowServerNoContext, boolean
preferredClientNoContext) {
if (
preferredClientWindowSize >
MAX_WINDOW_SIZE ||
preferredClientWindowSize <
MIN_WINDOW_SIZE) {
throw new
IllegalArgumentException(
"preferredServerWindowSize: " +
preferredClientWindowSize + " (expected: 8-15)");
}
if (
compressionLevel < 0 ||
compressionLevel > 9) {
throw new
IllegalArgumentException(
"compressionLevel: " +
compressionLevel + " (expected: 0-9)");
}
this.
compressionLevel =
compressionLevel;
this.
allowServerWindowSize =
allowServerWindowSize;
this.
preferredClientWindowSize =
preferredClientWindowSize;
this.
allowServerNoContext =
allowServerNoContext;
this.
preferredClientNoContext =
preferredClientNoContext;
}
@
Override
public
WebSocketServerExtension handshakeExtension(
WebSocketExtensionData extensionData) {
if (!
PERMESSAGE_DEFLATE_EXTENSION.
equals(
extensionData.
name())) {
return null;
}
boolean
deflateEnabled = 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 (
deflateEnabled &&
parametersIterator.
hasNext()) {
Entry<
String,
String>
parameter =
parametersIterator.
next();
if (
CLIENT_MAX_WINDOW.
equalsIgnoreCase(
parameter.
getKey())) {
// use preferred clientWindowSize because client is compatible with customization
clientWindowSize =
preferredClientWindowSize;
} else if (
SERVER_MAX_WINDOW.
equalsIgnoreCase(
parameter.
getKey())) {
// use provided windowSize if it is allowed
if (
allowServerWindowSize) {
serverWindowSize =
Integer.
parseInt(
parameter.
getValue());
if (
serverWindowSize >
MAX_WINDOW_SIZE ||
serverWindowSize <
MIN_WINDOW_SIZE) {
deflateEnabled = false;
}
} else {
deflateEnabled = false;
}
} else if (
CLIENT_NO_CONTEXT.
equalsIgnoreCase(
parameter.
getKey())) {
// use preferred clientNoContext because client is compatible with customization
clientNoContext =
preferredClientNoContext;
} else if (
SERVER_NO_CONTEXT.
equalsIgnoreCase(
parameter.
getKey())) {
// use server no context if allowed
if (
allowServerNoContext) {
serverNoContext = true;
} else {
deflateEnabled = false;
}
} else {
// unknown parameter
deflateEnabled = false;
}
}
if (
deflateEnabled) {
return new
PermessageDeflateExtension(
compressionLevel,
serverNoContext,
serverWindowSize,
clientNoContext,
clientWindowSize);
} else {
return null;
}
}
private static class
PermessageDeflateExtension implements
WebSocketServerExtension {
private final int
compressionLevel;
private final boolean
serverNoContext;
private final int
serverWindowSize;
private final boolean
clientNoContext;
private final int
clientWindowSize;
public
PermessageDeflateExtension(int
compressionLevel, boolean
serverNoContext,
int
serverWindowSize, boolean
clientNoContext, int
clientWindowSize) {
this.
compressionLevel =
compressionLevel;
this.
serverNoContext =
serverNoContext;
this.
serverWindowSize =
serverWindowSize;
this.
clientNoContext =
clientNoContext;
this.
clientWindowSize =
clientWindowSize;
}
@
Override
public int
rsv() {
return
RSV1;
}
@
Override
public
WebSocketExtensionEncoder newExtensionEncoder() {
return new
PerMessageDeflateEncoder(
compressionLevel,
clientWindowSize,
clientNoContext);
}
@
Override
public
WebSocketExtensionDecoder newExtensionDecoder() {
return new
PerMessageDeflateDecoder(
serverNoContext);
}
@
Override
public
WebSocketExtensionData newReponseData() {
HashMap<
String,
String>
parameters = new
HashMap<
String,
String>(4);
if (
serverNoContext) {
parameters.
put(
SERVER_NO_CONTEXT, null);
}
if (
clientNoContext) {
parameters.
put(
CLIENT_NO_CONTEXT, null);
}
if (
serverWindowSize !=
MAX_WINDOW_SIZE) {
parameters.
put(
SERVER_MAX_WINDOW,
Integer.
toString(
serverWindowSize));
}
if (
clientWindowSize !=
MAX_WINDOW_SIZE) {
parameters.
put(
CLIENT_MAX_WINDOW,
Integer.
toString(
clientWindowSize));
}
return new
WebSocketExtensionData(
PERMESSAGE_DEFLATE_EXTENSION,
parameters);
}
}
}