org.apache.hadoop.hdfs.server.datanode.web.SimpleHttpProxyHandler.java Source code

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Here is the source code for org.apache.hadoop.hdfs.server.datanode.web.SimpleHttpProxyHandler.java

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/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF 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 org.apache.hadoop.hdfs.server.datanode.web;

import io.netty.bootstrap.Bootstrap;
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.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;
import io.netty.handler.codec.http.DefaultFullHttpRequest;
import io.netty.handler.codec.http.DefaultHttpResponse;
import io.netty.handler.codec.http.HttpRequest;
import io.netty.handler.codec.http.HttpRequestEncoder;
import io.netty.handler.codec.http.HttpResponseEncoder;
import org.apache.commons.logging.Log;

import java.net.InetSocketAddress;

import static io.netty.handler.codec.http.HttpHeaders.Names.CONNECTION;
import static io.netty.handler.codec.http.HttpHeaders.Values;
import static io.netty.handler.codec.http.HttpResponseStatus.INTERNAL_SERVER_ERROR;
import static io.netty.handler.codec.http.HttpVersion.HTTP_1_1;

/**
 * Dead simple session-layer HTTP proxy. It gets the HTTP responses
 * inside the context, assuming that the remote peer is reasonable fast and
 * the response is small. The upper layer should be filtering out malicious
 * inputs.
 */
class SimpleHttpProxyHandler extends SimpleChannelInboundHandler<HttpRequest> {
    private String uri;
    private Channel proxiedChannel;
    private final InetSocketAddress host;
    static final Log LOG = DatanodeHttpServer.LOG;

    SimpleHttpProxyHandler(InetSocketAddress host) {
        this.host = host;
    }

    private static class Forwarder extends ChannelInboundHandlerAdapter {
        private final String uri;
        private final Channel client;

        private Forwarder(String uri, Channel client) {
            this.uri = uri;
            this.client = client;
        }

        @Override
        public void channelInactive(ChannelHandlerContext ctx) {
            closeOnFlush(client);
        }

        @Override
        public void channelRead(final ChannelHandlerContext ctx, Object msg) {
            client.writeAndFlush(msg).addListener(new ChannelFutureListener() {
                @Override
                public void operationComplete(ChannelFuture future) {
                    if (future.isSuccess()) {
                        ctx.channel().read();
                    } else {
                        LOG.debug("Proxy failed. Cause: ", future.cause());
                        future.channel().close();
                    }
                }
            });
        }

        @Override
        public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
            LOG.debug("Proxy for " + uri + " failed. cause: ", cause);
            closeOnFlush(ctx.channel());
        }
    }

    @Override
    public void channelRead0(final ChannelHandlerContext ctx, final HttpRequest req) {
        uri = req.getUri();
        final Channel client = ctx.channel();
        Bootstrap proxiedServer = new Bootstrap().group(client.eventLoop()).channel(NioSocketChannel.class)
                .handler(new ChannelInitializer<SocketChannel>() {
                    @Override
                    protected void initChannel(SocketChannel ch) throws Exception {
                        ChannelPipeline p = ch.pipeline();
                        p.addLast(new HttpRequestEncoder(), new Forwarder(uri, client));
                    }
                });
        ChannelFuture f = proxiedServer.connect(host);
        proxiedChannel = f.channel();
        f.addListener(new ChannelFutureListener() {
            @Override
            public void operationComplete(ChannelFuture future) throws Exception {
                if (future.isSuccess()) {
                    ctx.channel().pipeline().remove(HttpResponseEncoder.class);
                    HttpRequest newReq = new DefaultFullHttpRequest(HTTP_1_1, req.getMethod(), req.getUri());
                    newReq.headers().add(req.headers());
                    newReq.headers().set(CONNECTION, Values.CLOSE);
                    future.channel().writeAndFlush(newReq);
                } else {
                    DefaultHttpResponse resp = new DefaultHttpResponse(HTTP_1_1, INTERNAL_SERVER_ERROR);
                    resp.headers().set(CONNECTION, Values.CLOSE);
                    LOG.info("Proxy " + uri + " failed. Cause: ", future.cause());
                    ctx.writeAndFlush(resp).addListener(ChannelFutureListener.CLOSE);
                    client.close();
                }
            }
        });
    }

    @Override
    public void channelInactive(ChannelHandlerContext ctx) {
        if (proxiedChannel != null) {
            proxiedChannel.close();
            proxiedChannel = null;
        }
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
        LOG.info("Proxy for " + uri + " failed. cause: ", cause);
        if (proxiedChannel != null) {
            proxiedChannel.close();
            proxiedChannel = null;
        }
        ctx.close();
    }

    private static void closeOnFlush(Channel ch) {
        if (ch.isActive()) {
            ch.writeAndFlush(Unpooled.EMPTY_BUFFER).addListener(ChannelFutureListener.CLOSE);
        }
    }
}