[client] Refactor/iface pkg (#2646)

Refactor the flat code structure

client/iface/netstack/proxy.go

@@ -0,0 +1,65 @@
+package netstack
+
+import (
+	"net"
+
+	"github.com/things-go/go-socks5"
+
+	log "github.com/sirupsen/logrus"
+)
+
+const (
+	DefaultSocks5Port = 1080
+)
+
+// Proxy todo close server
+type Proxy struct {
+	server *socks5.Server
+
+	listener net.Listener
+	closed   bool
+}
+
+func NewSocks5(dialer Dialer) (*Proxy, error) {
+	server := socks5.NewServer(
+		socks5.WithDial(dialer.Dial),
+	)
+
+	return &Proxy{
+		server: server,
+	}, nil
+}
+
+func (s *Proxy) ListenAndServe(addr string) error {
+	listener, err := net.Listen("tcp", addr)
+	if err != nil {
+		log.Errorf("failed to create listener for socks5 proxy: %s", err)
+		return err
+	}
+	s.listener = listener
+
+	for {
+		conn, err := listener.Accept()
+		if err != nil {
+			if s.closed {
+				return nil
+			}
+			return err
+		}
+
+		go func() {
+			if err := s.server.ServeConn(conn); err != nil {
+				log.Errorf("failed to serve a connection: %s", err)
+			}
+		}()
+	}
+}
+
+func (s *Proxy) Close() error {
+	if s.listener == nil {
+		return nil
+	}
+
+	s.closed = true
+	return s.listener.Close()
+}