From 61f1f05339fa23c795ced6c0c622dee2ddd6394b Mon Sep 17 00:00:00 2001
From: ginuerzh <ginuerzh@gmail.com>
Date: Sun, 8 Oct 2023 22:04:36 +0800
Subject: [PATCH] fix panic in tun handler

---
 handler/tap/handler.go | 6 ++++++
 handler/tun/server.go  | 6 ++++++
 2 files changed, 12 insertions(+)

diff --git a/handler/tap/handler.go b/handler/tap/handler.go
index e73af6d..1d081a2 100644
--- a/handler/tap/handler.go
+++ b/handler/tap/handler.go
@@ -204,6 +204,9 @@ func (h *tapHandler) transport(tap net.Conn, conn net.PacketConn, raddr net.Addr
 					}
 					return err
 				}
+				if n == 0 {
+					return nil
+				}
 
 				src := waterutil.MACSource((*b)[:n])
 				dst := waterutil.MACDestination((*b)[:n])
@@ -260,6 +263,9 @@ func (h *tapHandler) transport(tap net.Conn, conn net.PacketConn, raddr net.Addr
 					err != shadowaead.ErrShortPacket {
 					return err
 				}
+				if n == 0 {
+					return nil
+				}
 
 				src := waterutil.MACSource((*b)[:n])
 				dst := waterutil.MACDestination((*b)[:n])
diff --git a/handler/tun/server.go b/handler/tun/server.go
index cc30a5b..09e7b66 100644
--- a/handler/tun/server.go
+++ b/handler/tun/server.go
@@ -49,6 +49,9 @@ func (h *tunHandler) transportServer(ctx context.Context, tun io.ReadWriter, con
 				if err != nil {
 					return ErrTun
 				}
+				if n == 0 {
+					return nil
+				}
 
 				var src, dst net.IP
 				if waterutil.IsIPv4((*b)[:n]) {
@@ -110,6 +113,9 @@ func (h *tunHandler) transportServer(ctx context.Context, tun io.ReadWriter, con
 				if err != nil {
 					return err
 				}
+				if n == 0 {
+					return nil
+				}
 				if n > keepAliveHeaderLength && bytes.Equal((*b)[:4], magicHeader) {
 					var peerIPs []net.IP
 					data := (*b)[keepAliveHeaderLength:n]