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/*
 * 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:
 *
 *   https://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.buffer.Unpooled;
import io.netty.channel.ChannelHandler.Sharable;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.MessageToMessageEncoder;

import java.util.List;

/**
 * Encodes a {@link WebSocketFrame} into a {@link ByteBuf}.
 * 

* For the detailed instruction on adding add Web Socket support to your HTTP server, take a look into the * WebSocketServer example located in the {@code io.netty.example.http.websocket} package. */ @Sharable public class WebSocket00FrameEncoder extends MessageToMessageEncoder implements WebSocketFrameEncoder { private static final ByteBuf _0X00 = Unpooled.unreleasableBuffer( Unpooled.directBuffer(1, 1).writeByte(0x00)).asReadOnly(); private static final ByteBuf _0XFF = Unpooled.unreleasableBuffer( Unpooled.directBuffer(1, 1).writeByte((byte) 0xFF)).asReadOnly(); private static final ByteBuf _0XFF_0X00 = Unpooled.unreleasableBuffer( Unpooled.directBuffer(2, 2).writeByte((byte) 0xFF).writeByte(0x00)).asReadOnly(); @Override protected void encode(ChannelHandlerContext ctx, WebSocketFrame msg, List out) throws Exception { if (msg instanceof TextWebSocketFrame) { // Text frame ByteBuf data = msg.content(); out.add(_0X00.duplicate()); out.add(data.retain()); out.add(_0XFF.duplicate()); } else if (msg instanceof CloseWebSocketFrame) { // Close frame, needs to call duplicate to allow multiple writes. // See https://github.com/netty/netty/issues/2768 out.add(_0XFF_0X00.duplicate()); } else { // Binary frame ByteBuf data = msg.content(); int dataLen = data.readableBytes(); ByteBuf buf = ctx.alloc().buffer(5); boolean release = true; try { // Encode type. buf.writeByte((byte) 0x80); // Encode length. int b1 = dataLen >>> 28 & 0x7F; int b2 = dataLen >>> 14 & 0x7F; int b3 = dataLen >>> 7 & 0x7F; int b4 = dataLen & 0x7F; if (b1 == 0) { if (b2 == 0) { if (b3 != 0) { buf.writeByte(b3 | 0x80); } buf.writeByte(b4); } else { buf.writeByte(b2 | 0x80); buf.writeByte(b3 | 0x80); buf.writeByte(b4); } } else { buf.writeByte(b1 | 0x80); buf.writeByte(b2 | 0x80); buf.writeByte(b3 | 0x80); buf.writeByte(b4); } // Encode binary data. out.add(buf); out.add(data.retain()); release = false; } finally { if (release) { buf.release(); } } } } }