feat: update

bin/main.dart

@@ -2,6 +2,12 @@ import 'dart:convert';
 import 'dart:io';
 import 'config.dart';
 
+int createdConnectionCount = 0;
+int runningConnectionCount = 0;
+int upstreamBytes = 0;
+int downstreamBytes = 0;
+Map<int, bool> createdConnectionMap = <int, bool>{};
+
 void main(List<String> arguments) {
   final listenAddress = "127.0.0.1";
   final listenPort = 8801;
@@ -34,9 +40,54 @@ void main(List<String> arguments) {
 
 void startListen(HostAndPort listen, HostAndPort target) {
   ServerSocket.bind(listen.host, listen.port).then((serverSocket) {
-    Socket.connect(target.host, target.port).then((clientSocket) {
-      // TODO ...
+    serverSocket.listen((Socket socket) {
+      Socket.connect(target.host, target.port).then((clientSocket) {
+        final createdConnectionIndex = createdConnectionCount;
+        createdConnectionCount++;
+        runningConnectionCount++;
+        createdConnectionMap[createdConnectionIndex] = true;
+        socket.listen(
+          (event) {
+            upstreamBytes += event.lengthInBytes;
+            clientSocket.write(event);
+          },
+          onError: (error, StackTrace stackTrace) {
+            if (createdConnectionMap.remove(createdConnectionIndex) != null) {
+              runningConnectionCount--;
+            }
+            print(
+                'Error in connection: ' + error + " " + stackTrace.toString());
+          },
+          onDone: () {
+            if (createdConnectionMap.remove(createdConnectionIndex) != null) {
+              runningConnectionCount--;
+            }
+            clientSocket.destroy();
+          },
+          cancelOnError: true,
+        );
+
+        clientSocket.listen(
+          (event) {
+            downstreamBytes += event.lengthInBytes;
+            socket.write(event);
+          },
+          onError: (error, StackTrace stackTrace) {
+            if (createdConnectionMap.remove(createdConnectionIndex) != null) {
+              runningConnectionCount--;
+            }
+            print(
+                'Error in connection: ' + error + " " + stackTrace.toString());
+          },
+          onDone: () {
+            if (createdConnectionMap.remove(createdConnectionIndex) != null) {
+              runningConnectionCount--;
+            }
+            socket.destroy();
+          },
+          cancelOnError: true,
+        );
+      });
     });
-    // serverSocket.listen((event) { })
   });
 }