/*
* Copyright 2012 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;
import io.netty.buffer.
ByteBuf;
import io.netty.channel.
ChannelHandlerContext;
import io.netty.handler.codec.
ReplayingDecoder;
import io.netty.handler.codec.
TooLongFrameException;
import java.util.
List;
import static io.netty.buffer.
ByteBufUtil.readBytes;
/**
* Decodes {@link ByteBuf}s into {@link WebSocketFrame}s.
* <p>
* For the detailed instruction on adding add Web Socket support to your HTTP server, take a look into the
* <tt>WebSocketServer</tt> example located in the {@code io.netty.example.http.websocket} package.
*/
public class
WebSocket00FrameDecoder extends
ReplayingDecoder<
Void> implements
WebSocketFrameDecoder {
static final int
DEFAULT_MAX_FRAME_SIZE = 16384;
private final long
maxFrameSize;
private boolean
receivedClosingHandshake;
public
WebSocket00FrameDecoder() {
this(
DEFAULT_MAX_FRAME_SIZE);
}
/**
* Creates a new instance of {@code WebSocketFrameDecoder} with the specified {@code maxFrameSize}. If the client
* sends a frame size larger than {@code maxFrameSize}, the channel will be closed.
*
* @param maxFrameSize
* the maximum frame size to decode
*/
public
WebSocket00FrameDecoder(int
maxFrameSize) {
this.
maxFrameSize =
maxFrameSize;
}
@
Override
protected void
decode(
ChannelHandlerContext ctx,
ByteBuf in,
List<
Object>
out) throws
Exception {
// Discard all data received if closing handshake was received before.
if (
receivedClosingHandshake) {
in.
skipBytes(
actualReadableBytes());
return;
}
// Decode a frame otherwise.
byte
type =
in.
readByte();
WebSocketFrame frame;
if ((
type & 0x80) == 0x80) {
// If the MSB on type is set, decode the frame length
frame =
decodeBinaryFrame(
ctx,
type,
in);
} else {
// Decode a 0xff terminated UTF-8 string
frame =
decodeTextFrame(
ctx,
in);
}
if (
frame != null) {
out.
add(
frame);
}
}
private
WebSocketFrame decodeBinaryFrame(
ChannelHandlerContext ctx, byte
type,
ByteBuf buffer) {
long
frameSize = 0;
int
lengthFieldSize = 0;
byte
b;
do {
b =
buffer.
readByte();
frameSize <<= 7;
frameSize |=
b & 0x7f;
if (
frameSize >
maxFrameSize) {
throw new
TooLongFrameException();
}
lengthFieldSize++;
if (
lengthFieldSize > 8) {
// Perhaps a malicious peer?
throw new
TooLongFrameException();
}
} while ((
b & 0x80) == 0x80);
if (
type == (byte) 0xFF &&
frameSize == 0) {
receivedClosingHandshake = true;
return new
CloseWebSocketFrame();
}
ByteBuf payload =
readBytes(
ctx.
alloc(),
buffer, (int)
frameSize);
return new
BinaryWebSocketFrame(
payload);
}
private
WebSocketFrame decodeTextFrame(
ChannelHandlerContext ctx,
ByteBuf buffer) {
int
ridx =
buffer.
readerIndex();
int
rbytes =
actualReadableBytes();
int
delimPos =
buffer.
indexOf(
ridx,
ridx +
rbytes, (byte) 0xFF);
if (
delimPos == -1) {
// Frame delimiter (0xFF) not found
if (
rbytes >
maxFrameSize) {
// Frame length exceeded the maximum
throw new
TooLongFrameException();
} else {
// Wait until more data is received
return null;
}
}
int
frameSize =
delimPos -
ridx;
if (
frameSize >
maxFrameSize) {
throw new
TooLongFrameException();
}
ByteBuf binaryData =
readBytes(
ctx.
alloc(),
buffer,
frameSize);
buffer.
skipBytes(1);
int
ffDelimPos =
binaryData.
indexOf(
binaryData.
readerIndex(),
binaryData.
writerIndex(), (byte) 0xFF);
if (
ffDelimPos >= 0) {
binaryData.
release();
throw new
IllegalArgumentException("a text frame should not contain 0xFF.");
}
return new
TextWebSocketFrame(
binaryData);
}
}