148 lines
5.2 KiB
Java
148 lines
5.2 KiB
Java
/*
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* Copyright 2019 The Netty Project
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*
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* The Netty Project licenses this file to you under the Apache License,
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* version 2.0 (the "License"); you may not use this file except in compliance
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* with the License. You may obtain a copy of the License at:
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*/
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package io.netty.handler.codec.http.websocketx;
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import io.netty.buffer.ByteBuf;
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import io.netty.channel.ChannelHandlerContext;
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import io.netty.handler.codec.ReplayingDecoder;
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import io.netty.handler.codec.TooLongFrameException;
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import java.util.Objects;
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import static io.netty.buffer.ByteBufUtil.readBytes;
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/**
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* Decodes {@link ByteBuf}s into {@link WebSocketFrame}s.
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* <p>
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* For the detailed instruction on adding add Web Socket support to your HTTP server, take a look into the
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* <tt>WebSocketServer</tt> example located in the {@code io.netty.example.http.websocket} package.
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*/
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public class WebSocket00FrameDecoder extends ReplayingDecoder<Void> implements WebSocketFrameDecoder {
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static final int DEFAULT_MAX_FRAME_SIZE = 16384;
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private final long maxFrameSize;
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private boolean receivedClosingHandshake;
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public WebSocket00FrameDecoder() {
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this(DEFAULT_MAX_FRAME_SIZE);
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}
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/**
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* Creates a new instance of {@code WebSocketFrameDecoder} with the specified {@code maxFrameSize}. If the client
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* sends a frame size larger than {@code maxFrameSize}, the channel will be closed.
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*
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* @param maxFrameSize
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* the maximum frame size to decode
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*/
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public WebSocket00FrameDecoder(int maxFrameSize) {
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this.maxFrameSize = maxFrameSize;
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}
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/**
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* Creates a new instance of {@code WebSocketFrameDecoder} with the specified {@code maxFrameSize}. If the client
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* sends a frame size larger than {@code maxFrameSize}, the channel will be closed.
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*
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* @param decoderConfig
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* Frames decoder configuration.
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*/
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public WebSocket00FrameDecoder(WebSocketDecoderConfig decoderConfig) {
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this.maxFrameSize = Objects.requireNonNull(decoderConfig, "decoderConfig").maxFramePayloadLength();
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}
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@Override
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protected void decode(ChannelHandlerContext ctx, ByteBuf in) throws Exception {
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// Discard all data received if closing handshake was received before.
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if (receivedClosingHandshake) {
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in.skipBytes(actualReadableBytes());
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return;
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}
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// Decode a frame otherwise.
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byte type = in.readByte();
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WebSocketFrame frame;
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if ((type & 0x80) == 0x80) {
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// If the MSB on type is set, decode the frame length
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frame = decodeBinaryFrame(ctx, type, in);
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} else {
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// Decode a 0xff terminated UTF-8 string
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frame = decodeTextFrame(ctx, in);
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}
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if (frame != null) {
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ctx.fireChannelRead(frame);
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}
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}
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private WebSocketFrame decodeBinaryFrame(ChannelHandlerContext ctx, byte type, ByteBuf buffer) {
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long frameSize = 0;
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int lengthFieldSize = 0;
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byte b;
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do {
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b = buffer.readByte();
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frameSize <<= 7;
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frameSize |= b & 0x7f;
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if (frameSize > maxFrameSize) {
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throw new TooLongFrameException();
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}
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lengthFieldSize++;
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if (lengthFieldSize > 8) {
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// Perhaps a malicious peer?
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throw new TooLongFrameException();
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}
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} while ((b & 0x80) == 0x80);
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if (type == (byte) 0xFF && frameSize == 0) {
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receivedClosingHandshake = true;
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return new CloseWebSocketFrame(true, 0, ctx.alloc().buffer(0));
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}
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ByteBuf payload = readBytes(ctx.alloc(), buffer, (int) frameSize);
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return new BinaryWebSocketFrame(payload);
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}
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private WebSocketFrame decodeTextFrame(ChannelHandlerContext ctx, ByteBuf buffer) {
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int ridx = buffer.readerIndex();
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int rbytes = actualReadableBytes();
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int delimPos = buffer.indexOf(ridx, ridx + rbytes, (byte) 0xFF);
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if (delimPos == -1) {
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// Frame delimiter (0xFF) not found
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if (rbytes > maxFrameSize) {
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// Frame length exceeded the maximum
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throw new TooLongFrameException();
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} else {
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// Wait until more data is received
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return null;
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}
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}
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int frameSize = delimPos - ridx;
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if (frameSize > maxFrameSize) {
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throw new TooLongFrameException();
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}
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ByteBuf binaryData = readBytes(ctx.alloc(), buffer, frameSize);
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buffer.skipBytes(1);
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int ffDelimPos = binaryData.indexOf(binaryData.readerIndex(), binaryData.writerIndex(), (byte) 0xFF);
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if (ffDelimPos >= 0) {
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binaryData.release();
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throw new IllegalArgumentException("a text frame should not contain 0xFF.");
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}
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return new TextWebSocketFrame(binaryData);
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}
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}
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