io.github.aomsweet.cyber.ClientRelayHandler Maven / Gradle / Ivy

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/*
  Copyright 2021 The Cyber Project

  Licensed 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 io.github.aomsweet.cyber;

import io.netty.channel.*;
import io.netty.util.internal.logging.InternalLogger;

import java.net.InetSocketAddress;
import java.util.Queue;

/**
 * @author aomsweet
 */
public abstract class ClientRelayHandler extends RelayHandler {

    protected Credentials credentials;
    protected InetSocketAddress serverAddress;

    public ClientRelayHandler(CyberServer cyber, InternalLogger logger) {
        super(cyber, logger);
    }

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        if (state == State.READY) {
            relay(ctx, msg);
        } else {
            channelRead0(ctx, msg);
        }
    }

    public abstract void channelRead0(ChannelHandlerContext ctx, Object msg) throws Exception;

    protected void doConnectServer(ChannelHandlerContext ctx, Channel clientChannel, Q request) throws Exception {
        ServerConnector connector = cyber.getConnector();
        UpstreamProxyManager upstreamProxyManager = cyber.getUpstreamProxyManager();
        Queue upstreamProxies = null;
        if (upstreamProxyManager != null) {
            upstreamProxies = upstreamProxyManager.lookupUpstreamProxies(request, credentials,
                clientChannel.remoteAddress(), serverAddress);
        }

        ChannelFuture channelFuture;
        if (upstreamProxies == null || upstreamProxies.isEmpty()) {
            channelFuture = connector.channel(serverAddress, ctx);
        } else {
            CompleteChannelPromise promise = new CompleteChannelPromise(ctx.channel().eventLoop());
            doConnectServer(ctx, connector, upstreamProxies, upstreamProxyManager, promise);
            channelFuture = promise;
        }
        channelFuture.addListener(future -> {
            if (future.isSuccess()) {
                try {
                    state = State.CONNECTED;
                    relayChannel = channelFuture.channel();
                    if (clientChannel.isActive()) {
                        onConnected(ctx, clientChannel, request);
                    }
                } catch (Exception e) {
                    logger.error("{}: {}", e.getClass().getName(), e.getMessage(), e);
                    release(ctx);
                }
            } else {
                logger.error("Unable to establish a remote connection.", future.cause());
                this.onConnectFailed(ctx, clientChannel, request);
            }
        });
    }

    protected void doConnectServer(ChannelHandlerContext ctx,
                                   ServerConnector connector,
                                   Queue upstreamProxies,
                                   UpstreamProxyManager upstreamProxyManager,
                                   CompleteChannelPromise promise) {
        UpstreamProxy upstreamProxy = upstreamProxies.poll();
        if (logger.isDebugEnabled()) {
            logger.debug("Use upstream proxy: [{}]", upstreamProxy);
        }
        connector.channel(serverAddress, ctx, upstreamProxy).addListener((ChannelFutureListener) future -> {
            if (future.isSuccess()) {
                promise.setChannel(future.channel()).setSuccess();
            } else {
                Throwable cause = future.cause();
                upstreamProxyManager.failConnectExceptionCaught(upstreamProxy, serverAddress, cause);
                if (upstreamProxies.peek() != null) {
                    doConnectServer(ctx, connector, upstreamProxies, upstreamProxyManager, promise);
                } else {
                    promise.setFailure(cause);
                }
            }
        });
    }

    public void doServerRelay(ChannelHandlerContext ctx) {
        if (relayChannel.isActive()) {
            relayChannel.pipeline().addLast(HandlerNames.RELAY, newServerRelayHandler(ctx));
            state = State.READY;
        } else {
            release(ctx);
        }
    }

    public ChannelHandler newServerRelayHandler(ChannelHandlerContext ctx) {
        return new ServerRelayHandler(cyber, ctx.channel());
    }

    protected abstract void onConnected(ChannelHandlerContext ctx, Channel clientChannel, Q request) throws Exception;

    protected void onConnectFailed(ChannelHandlerContext ctx, Channel clientChannel, Q request) throws Exception {
        release(ctx);
    }

    public ClientRelayHandler setCredentials(Credentials credentials) {
        this.credentials = credentials;
        return this;
    }

    public ClientRelayHandler setServerAddress(InetSocketAddress serverAddress) {
        this.serverAddress = serverAddress;
        return this;
    }
}