/*
* 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 com.facebook.presto.jdbc.internal.netty.handler.codec.http.websocketx;
import com.facebook.presto.jdbc.internal.netty.buffer.ChannelBuffer;
import com.facebook.presto.jdbc.internal.netty.channel.Channel;
import com.facebook.presto.jdbc.internal.netty.channel.ChannelHandlerContext;
import com.facebook.presto.jdbc.internal.netty.handler.codec.frame.TooLongFrameException;
import com.facebook.presto.jdbc.internal.netty.handler.codec.replay.ReplayingDecoder;
import com.facebook.presto.jdbc.internal.netty.handler.codec.replay.VoidEnum;
/**
* Decodes {@link ChannelBuffer}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 com.facebook.presto.jdbc.internal.netty.example.http.websocket} package.
*
* @apiviz.landmark
* @apiviz.uses com.facebook.presto.jdbc.internal.netty.handler.codec.http.websocket.WebSocketFrame
*/
public class WebSocket00FrameDecoder extends ReplayingDecoder<VoidEnum> {
private static final long 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
* @deprecated
*/
@Deprecated
public WebSocket00FrameDecoder(int maxFrameSize) {
this.maxFrameSize = maxFrameSize;
}
/**
* 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(long maxFrameSize) {
this.maxFrameSize = maxFrameSize;
}
@Override
protected Object decode(ChannelHandlerContext ctx, Channel channel, ChannelBuffer buffer, VoidEnum state)
throws Exception {
// Discard all data received if closing handshake was received before.
if (receivedClosingHandshake) {
buffer.skipBytes(actualReadableBytes());
return null;
}
// Decode a frame otherwise.
byte type = buffer.readByte();
if ((type & 0x80) == 0x80) {
// If the MSB on type is set, decode the frame length
return decodeBinaryFrame(type, buffer);
} else {
// Decode a 0xff terminated UTF-8 string
return decodeTextFrame(buffer);
}
}
private WebSocketFrame decodeBinaryFrame(byte type, ChannelBuffer buffer) throws TooLongFrameException {
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();
}
return new BinaryWebSocketFrame(buffer.readBytes((int) frameSize));
}
private WebSocketFrame decodeTextFrame(ChannelBuffer buffer) throws TooLongFrameException {
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();
}
ChannelBuffer binaryData = buffer.readBytes(frameSize);
buffer.skipBytes(1);
int ffDelimPos = binaryData.indexOf(binaryData.readerIndex(), binaryData.writerIndex(), (byte) 0xFF);
if (ffDelimPos >= 0) {
throw new IllegalArgumentException("a text frame should not contain 0xFF.");
}
return new TextWebSocketFrame(binaryData);
}
}