From 5eccd25e3ca863d78323f69a1ecb759b157d7570 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E4=B8=96=E7=95=8C?= <i@sekai.icu>
Date: Mon, 8 Apr 2024 11:11:04 +0800
Subject: [PATCH] Fix reset UDP MTU

---
 hysteria/packet.go  | 4 ++--
 hysteria2/packet.go | 4 ++--
 tuic/packet.go      | 4 ++--
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/hysteria/packet.go b/hysteria/packet.go
index 18110e1..18f7a97 100644
--- a/hysteria/packet.go
+++ b/hysteria/packet.go
@@ -208,7 +208,7 @@ func (c *udpPacketConn) WritePacket(buffer *buf.Buffer, destination M.Socksaddr)
 	if !errors.As(err, &tooLargeErr) {
 		return err
 	}
-	return c.writePackets(fragUDPMessage(message, int(tooLargeErr)))
+	return c.writePackets(fragUDPMessage(message, int(tooLargeErr)-3))
 }
 
 func (c *udpPacketConn) WriteTo(p []byte, addr net.Addr) (n int, err error) {
@@ -246,7 +246,7 @@ func (c *udpPacketConn) WriteTo(p []byte, addr net.Addr) (n int, err error) {
 	if !errors.As(err, &tooLargeErr) {
 		return
 	}
-	err = c.writePackets(fragUDPMessage(message, int(tooLargeErr)))
+	err = c.writePackets(fragUDPMessage(message, int(tooLargeErr)-3))
 	if err == nil {
 		return len(p), nil
 	}
diff --git a/hysteria2/packet.go b/hysteria2/packet.go
index 07887b0..ffe42cd 100644
--- a/hysteria2/packet.go
+++ b/hysteria2/packet.go
@@ -203,7 +203,7 @@ func (c *udpPacketConn) WritePacket(buffer *buf.Buffer, destination M.Socksaddr)
 	if !errors.As(err, &tooLargeErr) {
 		return err
 	}
-	return c.writePackets(fragUDPMessage(message, int(tooLargeErr)))
+	return c.writePackets(fragUDPMessage(message, int(tooLargeErr)-3))
 }
 
 func (c *udpPacketConn) WriteTo(p []byte, addr net.Addr) (n int, err error) {
@@ -239,7 +239,7 @@ func (c *udpPacketConn) WriteTo(p []byte, addr net.Addr) (n int, err error) {
 	if !errors.As(err, &tooLargeErr) {
 		return
 	}
-	err = c.writePackets(fragUDPMessage(message, int(tooLargeErr)))
+	err = c.writePackets(fragUDPMessage(message, int(tooLargeErr)-3))
 	if err == nil {
 		return len(p), nil
 	}
diff --git a/tuic/packet.go b/tuic/packet.go
index 1a358fa..fdc5192 100644
--- a/tuic/packet.go
+++ b/tuic/packet.go
@@ -227,7 +227,7 @@ func (c *udpPacketConn) WritePacket(buffer *buf.Buffer, destination M.Socksaddr)
 	if !errors.As(err, &tooLargeErr) {
 		return err
 	}
-	c.udpMTU = int(tooLargeErr)
+	c.udpMTU = int(tooLargeErr) - 3
 	c.udpMTUTime = time.Now()
 	return c.writePackets(fragUDPMessage(message, c.udpMTU))
 }
@@ -269,7 +269,7 @@ func (c *udpPacketConn) WriteTo(p []byte, addr net.Addr) (n int, err error) {
 	if !errors.As(err, &tooLargeErr) {
 		return
 	}
-	c.udpMTU = int(tooLargeErr)
+	c.udpMTU = int(tooLargeErr) - 3
 	c.udpMTUTime = time.Now()
 	err = c.writePackets(fragUDPMessage(message, c.udpMTU))
 	if err == nil {