透明代理(二)

二 、代理实现

1. 监听TCP链接

   var bindAddr=":3128"
   laddr, err := net.ResolveTCPAddr("tcp", bindAddr)
   if err != nil {
       log.Println(err)
       return
   }
   tl, err := net.ListenTCP("tcp", laddr)
   if err != nil {
       log.Println(err)
       return
   }
   for {
       conn, err := tl.AcceptTCP()
       if err != nil {
           log.Println(err)
           return
       }
       go handleConnection(conn)
   }

2. 建立远程链接+传输数据

   func handleConnection(conn *net.TCPConn) {
   	defer func() { _ = conn.Close() }()
   	originAddr, nConn, err := GetOriginalDst(conn)
   	if err != nil {
   		_ = conn.Close()
   		return
   	}
   	defer func() { _ = nConn.Close() }()
   	log.Println(originAddr.String())
   	rconn, err := dialWithUpStream(&originAddr)
   	if err != nil {
   		log.Println(err)
   		return
   	}
   	defer func() { _ = rconn.Close() }()
   	go func() {
   		_, _ = io.Copy(rconn, nConn)
   	}()
   	_, _ = io.Copy(nConn, rconn)
   }