add socks5 proxy support (apache#3624)

Author: nihongye

dubbo-remoting/dubbo-remoting-netty4/src/main/java/org/apache/dubbo/remoting/transport/netty4/NettyClient.java

@@ -21,6 +21,7 @@
 import org.apache.dubbo.common.Version;
 import org.apache.dubbo.common.logger.Logger;
 import org.apache.dubbo.common.logger.LoggerFactory;
+import org.apache.dubbo.common.utils.ConfigUtils;
 import org.apache.dubbo.common.utils.NetUtils;
 import org.apache.dubbo.common.utils.UrlUtils;
 import org.apache.dubbo.remoting.ChannelHandler;
@@ -35,11 +36,14 @@
 import io.netty.channel.ChannelOption;
 import io.netty.channel.nio.NioEventLoopGroup;
 import io.netty.channel.socket.nio.NioSocketChannel;
+import io.netty.handler.proxy.Socks5ProxyHandler;
 import io.netty.handler.timeout.IdleStateHandler;
 import io.netty.util.concurrent.DefaultThreadFactory;
 
 import static java.util.concurrent.TimeUnit.MILLISECONDS;
 
+import java.net.InetSocketAddress;
+
 /**
  * NettyClient.
  */
@@ -48,6 +52,12 @@ public class NettyClient extends AbstractClient {
     private static final Logger logger = LoggerFactory.getLogger(NettyClient.class);
 
     private static final NioEventLoopGroup nioEventLoopGroup = new NioEventLoopGroup(Constants.DEFAULT_IO_THREADS, new DefaultThreadFactory("NettyClientWorker", true));
+    
+    private static final String SOCKS_PROXY_HOST = "socksProxyHost";
+
+    private static final String SOCKS_PROXY_PORT = "socksProxyPort";
+
+    private static final String DEFAULT_SOCKS_PROXY_PORT = "1080";
 
     private Bootstrap bootstrap;
 
@@ -85,6 +95,12 @@ protected void initChannel(Channel ch) throws Exception {
                         .addLast("encoder", adapter.getEncoder())
                         .addLast("client-idle-handler", new IdleStateHandler(heartbeatInterval, 0, 0, MILLISECONDS))
                         .addLast("handler", nettyClientHandler);
+                String socksProxyHost = ConfigUtils.getProperty(SOCKS_PROXY_HOST);
+                if(socksProxyHost != null) {
+                    int socksProxyPort = Integer.parseInt(ConfigUtils.getProperty(SOCKS_PROXY_PORT, DEFAULT_SOCKS_PROXY_PORT));
+                    Socks5ProxyHandler socks5ProxyHandler = new Socks5ProxyHandler(new InetSocketAddress(socksProxyHost, socksProxyPort));
+                    ch.pipeline().addFirst(socks5ProxyHandler);
+                }
             }
         });
     }