/*
* 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.
*/
// (BSD License: http://www.opensource.org/licenses/bsd-license)
//
// Copyright (c) 2011, Joe Walnes and contributors
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or
// without modification, are permitted provided that the
// following conditions are met:
//
// * Redistributions of source code must retain the above
// copyright notice, this list of conditions and the
// following disclaimer.
//
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the
// following disclaimer in the documentation and/or other
// materials provided with the distribution.
//
// * Neither the name of the Webbit nor the names of
// its contributors may be used to endorse or promote products
// derived from this software without specific prior written
// permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
// CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
// INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
// GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
// BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
// LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
// OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.
package io.netty.handler.codec.http.websocketx;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.ByteToMessageDecoder;
import io.netty.handler.codec.CorruptedFrameException;
import io.netty.handler.codec.TooLongFrameException;
import io.netty.util.internal.logging.InternalLogger;
import io.netty.util.internal.logging.InternalLoggerFactory;
import java.nio.ByteOrder;
import java.util.List;
import static io.netty.buffer.ByteBufUtil.readBytes;
/**
* Decodes a web socket frame from wire protocol version 8 format. This code was forked from <a
* href="https://github.com/joewalnes/webbit">webbit</a> and modified.
*/
public class WebSocket08FrameDecoder extends ByteToMessageDecoder
implements WebSocketFrameDecoder {
enum State {
READING_FIRST,
READING_SECOND,
READING_SIZE,
MASKING_KEY,
PAYLOAD,
CORRUPT
}
private static final InternalLogger logger = InternalLoggerFactory.getInstance(WebSocket08FrameDecoder.class);
private static final byte OPCODE_CONT = 0x0;
private static final byte OPCODE_TEXT = 0x1;
private static final byte OPCODE_BINARY = 0x2;
private static final byte OPCODE_CLOSE = 0x8;
private static final byte OPCODE_PING = 0x9;
private static final byte OPCODE_PONG = 0xA;
private final long maxFramePayloadLength;
private final boolean allowExtensions;
private final boolean expectMaskedFrames;
private final boolean allowMaskMismatch;
private int fragmentedFramesCount;
private boolean frameFinalFlag;
private boolean frameMasked;
private int frameRsv;
private int frameOpcode;
private long framePayloadLength;
private byte[] maskingKey;
private int framePayloadLen1;
private boolean receivedClosingHandshake;
private State state = State.READING_FIRST;
/**
* Constructor
*
* @param expectMaskedFrames
* Web socket servers must set this to true processed incoming masked payload. Client implementations
* must set this to false.
* @param allowExtensions
* Flag to allow reserved extension bits to be used or not
* @param maxFramePayloadLength
* Maximum length of a frame's payload. Setting this to an appropriate value for you application
* helps check for denial of services attacks.
*/
public WebSocket08FrameDecoder(boolean expectMaskedFrames, boolean allowExtensions, int maxFramePayloadLength) {
this(expectMaskedFrames, allowExtensions, maxFramePayloadLength, false);
}
/**
* Constructor
*
* @param expectMaskedFrames
* Web socket servers must set this to true processed incoming masked payload. Client implementations
* must set this to false.
* @param allowExtensions
* Flag to allow reserved extension bits to be used or not
* @param maxFramePayloadLength
* Maximum length of a frame's payload. Setting this to an appropriate value for you application
* helps check for denial of services attacks.
* @param allowMaskMismatch
* When set to true, frames which are not masked properly according to the standard will still be
* accepted.
*/
public WebSocket08FrameDecoder(boolean expectMaskedFrames, boolean allowExtensions, int maxFramePayloadLength,
boolean allowMaskMismatch) {
this.expectMaskedFrames = expectMaskedFrames;
this.allowMaskMismatch = allowMaskMismatch;
this.allowExtensions = allowExtensions;
this.maxFramePayloadLength = maxFramePayloadLength;
}
@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;
}
switch (state) {
case READING_FIRST:
if (!in.isReadable()) {
return;
}
framePayloadLength = 0;
// FIN, RSV, OPCODE
byte b = in.readByte();
frameFinalFlag = (b & 0x80) != 0;
frameRsv = (b & 0x70) >> 4;
frameOpcode = b & 0x0F;
if (logger.isDebugEnabled()) {
logger.debug("Decoding WebSocket Frame opCode={}", frameOpcode);
}
state = State.READING_SECOND;
case READING_SECOND:
if (!in.isReadable()) {
return;
}
// MASK, PAYLOAD LEN 1
b = in.readByte();
frameMasked = (b & 0x80) != 0;
framePayloadLen1 = b & 0x7F;
if (frameRsv != 0 && !allowExtensions) {
protocolViolation(ctx, "RSV != 0 and no extension negotiated, RSV:" + frameRsv);
return;
}
if (!allowMaskMismatch && expectMaskedFrames != frameMasked) {
protocolViolation(ctx, "received a frame that is not masked as expected");
return;
}
if (frameOpcode > 7) { // control frame (have MSB in opcode set)
// control frames MUST NOT be fragmented
if (!frameFinalFlag) {
protocolViolation(ctx, "fragmented control frame");
return;
}
// control frames MUST have payload 125 octets or less
if (framePayloadLen1 > 125) {
protocolViolation(ctx, "control frame with payload length > 125 octets");
return;
}
// check for reserved control frame opcodes
if (!(frameOpcode == OPCODE_CLOSE || frameOpcode == OPCODE_PING
|| frameOpcode == OPCODE_PONG)) {
protocolViolation(ctx, "control frame using reserved opcode " + frameOpcode);
return;
}
// close frame : if there is a body, the first two bytes of the
// body MUST be a 2-byte unsigned integer (in network byte
// order) representing a getStatus code
if (frameOpcode == 8 && framePayloadLen1 == 1) {
protocolViolation(ctx, "received close control frame with payload len 1");
return;
}
} else { // data frame
// check for reserved data frame opcodes
if (!(frameOpcode == OPCODE_CONT || frameOpcode == OPCODE_TEXT
|| frameOpcode == OPCODE_BINARY)) {
protocolViolation(ctx, "data frame using reserved opcode " + frameOpcode);
return;
}
// check opcode vs message fragmentation state 1/2
if (fragmentedFramesCount == 0 && frameOpcode == OPCODE_CONT) {
protocolViolation(ctx, "received continuation data frame outside fragmented message");
return;
}
// check opcode vs message fragmentation state 2/2
if (fragmentedFramesCount != 0 && frameOpcode != OPCODE_CONT && frameOpcode != OPCODE_PING) {
protocolViolation(ctx,
"received non-continuation data frame while inside fragmented message");
return;
}
}
state = State.READING_SIZE;
case READING_SIZE:
// Read frame payload length
if (framePayloadLen1 == 126) {
if (in.readableBytes() < 2) {
return;
}
framePayloadLength = in.readUnsignedShort();
if (framePayloadLength < 126) {
protocolViolation(ctx, "invalid data frame length (not using minimal length encoding)");
return;
}
} else if (framePayloadLen1 == 127) {
if (in.readableBytes() < 8) {
return;
}
framePayloadLength = in.readLong();
// TODO: check if it's bigger than 0x7FFFFFFFFFFFFFFF, Maybe
// just check if it's negative?
if (framePayloadLength < 65536) {
protocolViolation(ctx, "invalid data frame length (not using minimal length encoding)");
return;
}
} else {
framePayloadLength = framePayloadLen1;
}
if (framePayloadLength > maxFramePayloadLength) {
protocolViolation(ctx, "Max frame length of " + maxFramePayloadLength + " has been exceeded.");
return;
}
if (logger.isDebugEnabled()) {
logger.debug("Decoding WebSocket Frame length={}", framePayloadLength);
}
state = State.MASKING_KEY;
case MASKING_KEY:
if (frameMasked) {
if (in.readableBytes() < 4) {
return;
}
if (maskingKey == null) {
maskingKey = new byte[4];
}
in.readBytes(maskingKey);
}
state = State.PAYLOAD;
case PAYLOAD:
if (in.readableBytes() < framePayloadLength) {
return;
}
ByteBuf payloadBuffer = null;
try {
payloadBuffer = readBytes(ctx.alloc(), in, toFrameLength(framePayloadLength));
// Now we have all the data, the next checkpoint must be the next
// frame
state = State.READING_FIRST;
// Unmask data if needed
if (frameMasked) {
unmask(payloadBuffer);
}
// Processing ping/pong/close frames because they cannot be
// fragmented
if (frameOpcode == OPCODE_PING) {
out.add(new PingWebSocketFrame(frameFinalFlag, frameRsv, payloadBuffer));
payloadBuffer = null;
return;
}
if (frameOpcode == OPCODE_PONG) {
out.add(new PongWebSocketFrame(frameFinalFlag, frameRsv, payloadBuffer));
payloadBuffer = null;
return;
}
if (frameOpcode == OPCODE_CLOSE) {
receivedClosingHandshake = true;
checkCloseFrameBody(ctx, payloadBuffer);
out.add(new CloseWebSocketFrame(frameFinalFlag, frameRsv, payloadBuffer));
payloadBuffer = null;
return;
}
// Processing for possible fragmented messages for text and binary
// frames
if (frameFinalFlag) {
// Final frame of the sequence. Apparently ping frames are
// allowed in the middle of a fragmented message
if (frameOpcode != OPCODE_PING) {
fragmentedFramesCount = 0;
}
} else {
// Increment counter
fragmentedFramesCount++;
}
// Return the frame
if (frameOpcode == OPCODE_TEXT) {
out.add(new TextWebSocketFrame(frameFinalFlag, frameRsv, payloadBuffer));
payloadBuffer = null;
return;
} else if (frameOpcode == OPCODE_BINARY) {
out.add(new BinaryWebSocketFrame(frameFinalFlag, frameRsv, payloadBuffer));
payloadBuffer = null;
return;
} else if (frameOpcode == OPCODE_CONT) {
out.add(new ContinuationWebSocketFrame(frameFinalFlag, frameRsv,
payloadBuffer));
payloadBuffer = null;
return;
} else {
throw new UnsupportedOperationException("Cannot decode web socket frame with opcode: "
+ frameOpcode);
}
} finally {
if (payloadBuffer != null) {
payloadBuffer.release();
}
}
case CORRUPT:
if (in.isReadable()) {
// If we don't keep reading Netty will throw an exception saying
// we can't return null if no bytes read and state not changed.
in.readByte();
}
return;
default:
throw new Error("Shouldn't reach here.");
}
}
private void unmask(ByteBuf frame) {
int i = frame.readerIndex();
int end = frame.writerIndex();
ByteOrder order = frame.order();
// Remark: & 0xFF is necessary because Java will do signed expansion from
// byte to int which we don't want.
int intMask = ((maskingKey[0] & 0xFF) << 24)
| ((maskingKey[1] & 0xFF) << 16)
| ((maskingKey[2] & 0xFF) << 8)
| (maskingKey[3] & 0xFF);
// If the byte order of our buffers it little endian we have to bring our mask
// into the same format, because getInt() and writeInt() will use a reversed byte order
if (order == ByteOrder.LITTLE_ENDIAN) {
intMask = Integer.reverseBytes(intMask);
}
for (; i + 3 < end; i += 4) {
int unmasked = frame.getInt(i) ^ intMask;
frame.setInt(i, unmasked);
}
for (; i < end; i++) {
frame.setByte(i, frame.getByte(i) ^ maskingKey[i % 4]);
}
}
private void protocolViolation(ChannelHandlerContext ctx, String reason) {
protocolViolation(ctx, new CorruptedFrameException(reason));
}
private void protocolViolation(ChannelHandlerContext ctx, CorruptedFrameException ex) {
state = State.CORRUPT;
if (ctx.channel().isActive()) {
Object closeMessage;
if (receivedClosingHandshake) {
closeMessage = Unpooled.EMPTY_BUFFER;
} else {
closeMessage = new CloseWebSocketFrame(1002, null);
}
ctx.writeAndFlush(closeMessage).addListener(ChannelFutureListener.CLOSE);
}
throw ex;
}
private static int toFrameLength(long l) {
if (l > Integer.MAX_VALUE) {
throw new TooLongFrameException("Length:" + l);
} else {
return (int) l;
}
}
/** */
protected void checkCloseFrameBody(
ChannelHandlerContext ctx, ByteBuf buffer) {
if (buffer == null || !buffer.isReadable()) {
return;
}
if (buffer.readableBytes() == 1) {
protocolViolation(ctx, "Invalid close frame body");
}
// Save reader index
int idx = buffer.readerIndex();
buffer.readerIndex(0);
// Must have 2 byte integer within the valid range
int statusCode = buffer.readShort();
if (statusCode >= 0 && statusCode <= 999 || statusCode >= 1004 && statusCode <= 1006
|| statusCode >= 1012 && statusCode <= 2999) {
protocolViolation(ctx, "Invalid close frame getStatus code: " + statusCode);
}
// May have UTF-8 message
if (buffer.isReadable()) {
try {
new Utf8Validator().check(buffer);
} catch (CorruptedFrameException ex) {
protocolViolation(ctx, ex);
}
}
// Restore reader index
buffer.readerIndex(idx);
}
}