From 980d4bf9a38d8fca9fb96b51671695569530bfe2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E4=B8=96=E7=95=8C?= <i@sekai.icu>
Date: Sun, 26 Mar 2023 10:37:44 +0800
Subject: [PATCH] Flush DNS cache on macOS

---
 tun_darwin.go  |  7 +++++++
 tun_windows.go | 13 +++++++------
 2 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/tun_darwin.go b/tun_darwin.go
index 4c33161..8dc8b17 100644
--- a/tun_darwin.go
+++ b/tun_darwin.go
@@ -13,6 +13,7 @@ import (
 	"github.com/sagernet/sing/common/bufio"
 	E "github.com/sagernet/sing/common/exceptions"
 	N "github.com/sagernet/sing/common/network"
+	"github.com/sagernet/sing/common/shell"
 
 	"golang.org/x/net/route"
 	"golang.org/x/sys/unix"
@@ -101,6 +102,7 @@ func (t *NativeTun) Write(p []byte) (n int, err error) {
 }
 
 func (t *NativeTun) Close() error {
+	flushDNSCache()
 	return t.tunFile.Close()
 }
 
@@ -285,6 +287,7 @@ func configure(tunFd int, ifIndex int, name string, options Options) error {
 				}
 			}
 		}
+		flushDNSCache()
 	}
 	return nil
 }
@@ -326,3 +329,7 @@ func addRoute(destination netip.Prefix, gateway netip.Addr) error {
 		return common.Error(unix.Write(socketFd, request))
 	})
 }
+
+func flushDNSCache() {
+	shell.Exec("dscacheutil", "-flushcache").Start()
+}
diff --git a/tun_windows.go b/tun_windows.go
index 8396444..488f8a7 100644
--- a/tun_windows.go
+++ b/tun_windows.go
@@ -116,6 +116,10 @@ func (t *NativeTun) configure() error {
 				}
 			}
 		}
+		err := windnsapi.FlushResolverCache()
+		if err != nil {
+			return err
+		}
 	}
 	if len(t.options.Inet4Address) > 0 {
 		inetIf, err := luid.IPInterface(winipcfg.AddressFamily(windows.AF_INET))
@@ -331,11 +335,6 @@ func (t *NativeTun) configure() error {
 		if err != nil {
 			return os.NewSyscallError("FwpmFilterAdd0", err)
 		}
-
-		err = windnsapi.FlushResolverCache()
-		if err != nil {
-			return err
-		}
 	}
 
 	return nil
@@ -479,7 +478,9 @@ func (t *NativeTun) Close() error {
 		if t.fwpmSession != 0 {
 			winsys.FwpmEngineClose0(t.fwpmSession)
 		}
-		windnsapi.FlushResolverCache()
+		if t.options.AutoRoute {
+			windnsapi.FlushResolverCache()
+		}
 	})
 	return err
 }