Java tutorial
/* * 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.netty.grpc.proxy.demo.handler; import io.netty.bootstrap.Bootstrap; import io.netty.buffer.ByteBuf; import io.netty.buffer.ByteBufAllocator; import io.netty.buffer.ByteBufUtil; import io.netty.buffer.Unpooled; import io.netty.channel.Channel; import io.netty.channel.ChannelFuture; import io.netty.channel.ChannelFutureListener; import io.netty.channel.ChannelHandlerContext; import io.netty.channel.ChannelInboundHandlerAdapter; import io.netty.channel.ChannelOption; import io.netty.handler.codec.http2.*; import io.netty.handler.logging.LogLevel; import java.util.concurrent.atomic.AtomicInteger; import static io.netty.buffer.ByteBufUtil.hexDump; import static io.netty.handler.codec.http2.Http2CodecUtil.readUnsignedInt; import static io.netty.handler.codec.http2.Http2Error.PROTOCOL_ERROR; import static io.netty.handler.codec.http2.Http2Exception.connectionError; import static java.lang.Math.min; public class GrpcProxyFrontendHandler extends ChannelInboundHandlerAdapter { private final String[] remoteHosts; private final int[] remotePorts; private final Channel[] outboundChannels; private boolean first = true; private final AtomicInteger counter; private Channel selectedChannel; public GrpcProxyFrontendHandler(String[] remoteHosts, int[] remotePorts, AtomicInteger counter) { this.remoteHosts = remoteHosts; this.remotePorts = remotePorts; this.outboundChannels = new Channel[remoteHosts.length]; this.counter = counter; } @Override public void channelActive(ChannelHandlerContext ctx) { final Channel inboundChannel = ctx.channel(); // ?? Bootstrap b = new Bootstrap(); b.group(inboundChannel.eventLoop()).channel(ctx.channel().getClass()) .handler(new GrpcProxyBackendHandler(inboundChannel)).option(ChannelOption.AUTO_READ, false); for (int i = 0; i < remoteHosts.length; i++) { final ChannelFuture f = b.connect(remoteHosts[i], remotePorts[i]); outboundChannels[i] = f.channel(); f.addListener(new ChannelFutureListener() { public void operationComplete(ChannelFuture future) { if (future.isSuccess()) { // connection complete start to read first data inboundChannel.read(); // System.out.println(f.channel().remoteAddress() + ", " + f.channel().localAddress()); } else { // Close the connection if the connection attempt has failed. // System.out.println("channelActive close" + inboundChannel.remoteAddress() + ", " + inboundChannel.localAddress()); inboundChannel.close(); } } }); } } @Override public void channelRead(final ChannelHandlerContext ctx, Object msg) { readFrame(ctx, (ByteBuf) msg); } private void readFrame(final ChannelHandlerContext ctx, ByteBuf buf) { if (first) { try { readClientPrefaceString(buf); } catch (Http2Exception e) { e.printStackTrace(); } first = false; } while (buf.readableBytes() > 0) { int payload = buf.readUnsignedMedium(); int frameType = buf.readByte(); Http2Flags flags = new Http2Flags(buf.readUnsignedByte()); int streamId = readUnsignedInt(buf); ByteBuf payloadBuf = buf.readBytes(payload); ByteBuf copy = ctx.alloc().buffer(); switch (frameType) { case Http2FrameTypes.SETTINGS: handleSettingFrame(ctx, flags); break; case Http2FrameTypes.WINDOW_UPDATE: handleWindowsUpdateFrame(ctx); break; case Http2FrameTypes.HEADERS: copy.writeMedium(payload); copy.writeByte(frameType); copy.writeByte(flags.value()); copy.writeInt(streamId); copy.writeBytes(payloadBuf); handleHeaderFrame(ctx, copy, streamId); break; case Http2FrameTypes.DATA: copy.writeMedium(payload); copy.writeByte(frameType); copy.writeByte(flags.value()); copy.writeInt(streamId); copy.writeBytes(payloadBuf); handleDataFrame(ctx, copy, streamId); break; default: break; } } } private boolean readClientPrefaceString(ByteBuf in) throws Http2Exception { ByteBuf clientPrefaceString = Http2CodecUtil.connectionPrefaceBuf(); int prefaceRemaining = clientPrefaceString.readableBytes(); int bytesRead = min(in.readableBytes(), prefaceRemaining); // If the input so far doesn't match the preface, break the connection. if (bytesRead == 0 || !ByteBufUtil.equals(in, in.readerIndex(), clientPrefaceString, clientPrefaceString.readerIndex(), bytesRead)) { String receivedBytes = hexDump(in, in.readerIndex(), min(in.readableBytes(), clientPrefaceString.readableBytes())); throw connectionError(PROTOCOL_ERROR, "HTTP/2 client preface string missing or corrupt. " + "Hex dump for received bytes: %s", receivedBytes); } in.skipBytes(bytesRead); clientPrefaceString.skipBytes(bytesRead); if (!clientPrefaceString.isReadable()) { // Entire preface has been read. clientPrefaceString.release(); return true; } return false; } private void handleSettingFrame(final ChannelHandlerContext ctx, Http2Flags flags) { ByteBufAllocator alloc = ctx.alloc(); ByteBuf byteBuf = alloc.buffer(); if (!flags.ack()) { // System.out.println("********************* setting received ..."); //00 00 0c 04 00 00 00 00 00 00 03 7f ff ff ff 00 byteBuf.writeByte(0x00); byteBuf.writeByte(0x00); byteBuf.writeByte(0x0c); byteBuf.writeByte(0x04); byteBuf.writeByte(0x00); byteBuf.writeByte(0x00); byteBuf.writeByte(0x00); byteBuf.writeByte(0x00); byteBuf.writeByte(0x00); byteBuf.writeByte(0x00); byteBuf.writeByte(0x03); byteBuf.writeByte(0x7f); byteBuf.writeByte(0xff); byteBuf.writeByte(0xff); byteBuf.writeByte(0xff); byteBuf.writeByte(0x00); //04 00 10 00 00 byteBuf.writeByte(0x04); byteBuf.writeByte(0x00); byteBuf.writeByte(0x10); byteBuf.writeByte(0x00); byteBuf.writeByte(0x00); } else { // System.out.println("********************* setting ack received ..."); //00 00 00 04 01 00 00 00 00 byteBuf.writeByte(0x00); byteBuf.writeByte(0x00); byteBuf.writeByte(0x00); byteBuf.writeByte(0x04); byteBuf.writeByte(0x01); byteBuf.writeByte(0x00); byteBuf.writeByte(0x00); byteBuf.writeByte(0x00); byteBuf.writeByte(0x00); } ctx.writeAndFlush(byteBuf).addListener(new ChannelFutureListener() { public void operationComplete(ChannelFuture future) { if (future.isSuccess()) { // System.out.println(" ...operationComplete isSuccess"); ctx.channel().read(); } else { // System.out.println("...operationComplete failure"); future.channel().close(); } } }); } private void handleWindowsUpdateFrame(final ChannelHandlerContext ctx) { ByteBufAllocator alloc = ctx.alloc(); ByteBuf byteBuf = alloc.buffer(); // 00 00 04 08 00 00 00 00 00 00 0f 00 01 byteBuf.writeByte(0x00); byteBuf.writeByte(0x00); byteBuf.writeByte(0x04); byteBuf.writeByte(0x08); byteBuf.writeByte(0x00); byteBuf.writeByte(0x00); byteBuf.writeByte(0x00); byteBuf.writeByte(0x00); byteBuf.writeByte(0x00); byteBuf.writeByte(0x00); byteBuf.writeByte(0x0f); byteBuf.writeByte(0x00); byteBuf.writeByte(0x01); ctx.writeAndFlush(byteBuf).addListener(new ChannelFutureListener() { public void operationComplete(ChannelFuture future) { if (future.isSuccess()) { ctx.channel().read(); } else { future.channel().close(); } } }); } private void handleHeaderFrame(final ChannelHandlerContext ctx, final ByteBuf copy, final int streamId) { // System.out.print("******************************** headers received"); forwardThisFrame(ctx, copy, streamId, 1); } private void handleDataFrame(final ChannelHandlerContext ctx, final ByteBuf copy, int streamId) { // System.out.print("******************************** data received"); forwardThisFrame(ctx, copy, streamId, 2); } private void forwardThisFrame(final ChannelHandlerContext ctx, final ByteBuf copy, int streamId, final int type) { if (selectedChannel == null) { int select = (counter.getAndIncrement()) % remoteHosts.length; selectedChannel = outboundChannels[select]; } //int select = 0; // System.out.println("---------------------------------select:" + select + "," + ByteBufUtil.hexDump(copy)); final Channel inboundChannel = ctx.channel(); selectedChannel.writeAndFlush(copy).addListener(new ChannelFutureListener() { public void operationComplete(ChannelFuture future) { if (future.isSuccess()) { // System.out.println("forward success ------------------------------------------type=" + type); inboundChannel.read(); } else { // System.out.println("forward failure------------------------------------------"); inboundChannel.close(); } } }); } @Override public void channelInactive(ChannelHandlerContext ctx) { if (outboundChannels != null) { for (int i = 0; i < outboundChannels.length; i++) { if (outboundChannels[i].isActive()) { closeOnFlush(outboundChannels[i]); } } } } @Override public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) { cause.printStackTrace(); closeOnFlush(ctx.channel()); } /** * Closes the specified channel after all queued write requests are flushed. */ static void closeOnFlush(Channel ch) { if (ch.isActive()) { // System.out.println("----------------------------------------------"); ch.writeAndFlush(Unpooled.EMPTY_BUFFER).addListener(ChannelFutureListener.CLOSE); } } }