From 442cceb9fa07e84980d7c7ec5a4c8ac1553932d1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E4=B8=96=E7=95=8C?= <i@sekai.icu>
Date: Thu, 12 Dec 2024 20:40:01 +0800
Subject: [PATCH] Fix disable UDP fragment

---
 common/control/frag_darwin.go  | 17 ++++++++++++-----
 common/control/frag_linux.go   | 16 +++++++++-------
 common/control/frag_windows.go | 16 +++++++++-------
 3 files changed, 30 insertions(+), 19 deletions(-)

diff --git a/common/control/frag_darwin.go b/common/control/frag_darwin.go
index 567a821..f76b241 100644
--- a/common/control/frag_darwin.go
+++ b/common/control/frag_darwin.go
@@ -4,19 +4,26 @@ import (
 	"os"
 	"syscall"
 
+	N "github.com/sagernet/sing/common/network"
+
 	"golang.org/x/sys/unix"
 )
 
 func DisableUDPFragment() Func {
 	return func(network, address string, conn syscall.RawConn) error {
+		if N.NetworkName(network) != N.NetworkUDP {
+			return nil
+		}
 		return Raw(conn, func(fd uintptr) error {
-			switch network {
-			case "udp4":
-				if err := unix.SetsockoptInt(int(fd), unix.IPPROTO_IP, unix.IP_DONTFRAG, 1); err != nil {
+			if network == "udp" || network == "udp4" {
+				err := unix.SetsockoptInt(int(fd), unix.IPPROTO_IP, unix.IP_DONTFRAG, 1)
+				if err != nil {
 					return os.NewSyscallError("SETSOCKOPT IP_DONTFRAG", err)
 				}
-			case "udp6":
-				if err := unix.SetsockoptInt(int(fd), unix.IPPROTO_IPV6, unix.IPV6_DONTFRAG, 1); err != nil {
+			}
+			if network == "udp" || network == "udp6" {
+				err := unix.SetsockoptInt(int(fd), unix.IPPROTO_IPV6, unix.IPV6_DONTFRAG, 1)
+				if err != nil {
 					return os.NewSyscallError("SETSOCKOPT IPV6_DONTFRAG", err)
 				}
 			}
diff --git a/common/control/frag_linux.go b/common/control/frag_linux.go
index 5cb5fca..3bf9d57 100644
--- a/common/control/frag_linux.go
+++ b/common/control/frag_linux.go
@@ -11,17 +11,19 @@ import (
 
 func DisableUDPFragment() Func {
 	return func(network, address string, conn syscall.RawConn) error {
-		switch N.NetworkName(network) {
-		case N.NetworkUDP:
-		default:
+		if N.NetworkName(network) != N.NetworkUDP {
 			return nil
 		}
 		return Raw(conn, func(fd uintptr) error {
-			if err := unix.SetsockoptInt(int(fd), unix.IPPROTO_IP, unix.IP_MTU_DISCOVER, unix.IP_PMTUDISC_DO); err != nil {
-				return os.NewSyscallError("SETSOCKOPT IP_MTU_DISCOVER IP_PMTUDISC_DO", err)
+			if network == "udp" || network == "udp4" {
+				err := unix.SetsockoptInt(int(fd), unix.IPPROTO_IP, unix.IP_MTU_DISCOVER, unix.IP_PMTUDISC_DO)
+				if err != nil {
+					return os.NewSyscallError("SETSOCKOPT IP_MTU_DISCOVER IP_PMTUDISC_DO", err)
+				}
 			}
-			if network == "udp6" {
-				if err := unix.SetsockoptInt(int(fd), unix.IPPROTO_IPV6, unix.IPV6_MTU_DISCOVER, unix.IP_PMTUDISC_DO); err != nil {
+			if network == "udp" || network == "udp6" {
+				err := unix.SetsockoptInt(int(fd), unix.IPPROTO_IPV6, unix.IPV6_MTU_DISCOVER, unix.IP_PMTUDISC_DO)
+				if err != nil {
 					return os.NewSyscallError("SETSOCKOPT IPV6_MTU_DISCOVER IP_PMTUDISC_DO", err)
 				}
 			}
diff --git a/common/control/frag_windows.go b/common/control/frag_windows.go
index bf02948..8e9bb83 100644
--- a/common/control/frag_windows.go
+++ b/common/control/frag_windows.go
@@ -25,17 +25,19 @@ const (
 
 func DisableUDPFragment() Func {
 	return func(network, address string, conn syscall.RawConn) error {
-		switch N.NetworkName(network) {
-		case N.NetworkUDP:
-		default:
+		if N.NetworkName(network) != N.NetworkUDP {
 			return nil
 		}
 		return Raw(conn, func(fd uintptr) error {
-			if err := windows.SetsockoptInt(windows.Handle(fd), windows.IPPROTO_IP, IP_MTU_DISCOVER, IP_PMTUDISC_DO); err != nil {
-				return os.NewSyscallError("SETSOCKOPT IP_MTU_DISCOVER IP_PMTUDISC_DO", err)
+			if network == "udp" || network == "udp4" {
+				err := windows.SetsockoptInt(windows.Handle(fd), windows.IPPROTO_IP, IP_MTU_DISCOVER, IP_PMTUDISC_DO)
+				if err != nil {
+					return os.NewSyscallError("SETSOCKOPT IP_MTU_DISCOVER IP_PMTUDISC_DO", err)
+				}
 			}
-			if network == "udp6" {
-				if err := windows.SetsockoptInt(windows.Handle(fd), windows.IPPROTO_IPV6, IPV6_MTU_DISCOVER, IP_PMTUDISC_DO); err != nil {
+			if network == "udp" || network == "udp6" {
+				err := windows.SetsockoptInt(windows.Handle(fd), windows.IPPROTO_IPV6, IPV6_MTU_DISCOVER, IP_PMTUDISC_DO)
+				if err != nil {
 					return os.NewSyscallError("SETSOCKOPT IPV6_MTU_DISCOVER IP_PMTUDISC_DO", err)
 				}
 			}