chore: limit tuicv5's maxUdpRelayPacketSize up to 1200-PacketOverHead

adapter/outbound/tuic.go

@@ -323,6 +323,10 @@ func NewTuic(option TuicOption) (*Tuic, error) {
 
 		t.client = tuic.NewPoolClientV4(clientOption)
 	} else {
+		maxUdpRelayPacketSize := option.MaxUdpRelayPacketSize
+		if maxUdpRelayPacketSize > tuic.MaxFragSizeV5 {
+			maxUdpRelayPacketSize = tuic.MaxFragSizeV5
+		}
 		clientOption := &tuic.ClientOptionV5{
 			TlsConfig:             tlsConfig,
 			QuicConfig:            quicConfig,
@@ -331,7 +335,7 @@ func NewTuic(option TuicOption) (*Tuic, error) {
 			UdpRelayMode:          udpRelayMode,
 			CongestionController:  option.CongestionController,
 			ReduceRtt:             option.ReduceRtt,
-			MaxUdpRelayPacketSize: option.MaxUdpRelayPacketSize,
+			MaxUdpRelayPacketSize: maxUdpRelayPacketSize,
 			MaxOpenStreams:        clientMaxOpenStreams,
 			CWND:                  option.CWND,
 		}

transport/tuic/server.go

@@ -223,6 +223,10 @@ func NewServer(option *ServerOption, pc net.PacketConn) (*Server, error) {
 		}
 	}
 	if len(option.Users) > 0 {
+		maxUdpRelayPacketSize := option.MaxUdpRelayPacketSize
+		if maxUdpRelayPacketSize > MaxFragSizeV5 {
+			maxUdpRelayPacketSize = MaxFragSizeV5
+		}
 		server.optionV5 = &v5.ServerOption{
 			HandleTcpFn:           option.HandleTcpFn,
 			HandleUdpFn:           option.HandleUdpFn,

transport/tuic/tuic.go

@@ -30,6 +30,7 @@ const DefaultConnectionReceiveWindow = common.DefaultConnectionReceiveWindow
 var GenTKN = v4.GenTKN
 var PacketOverHeadV4 = v4.PacketOverHead
 var PacketOverHeadV5 = v5.PacketOverHead
+var MaxFragSizeV5 = v5.MaxFragSize
 
 type UdpRelayMode = common.UdpRelayMode
 

transport/tuic/v5/frag.go

@@ -9,6 +9,11 @@ import (
 	"github.com/metacubex/quic-go"
 )
 
+// MaxFragSize is a safe udp relay packet size
+// because tuicv5 support udp fragment so we unneeded to do a magic modify for quic-go to increase MaxDatagramFrameSize
+// it may not work fine in some platform
+var MaxFragSize = 1200 - PacketOverHead
+
 func fragWriteNative(quicConn quic.Connection, packet Packet, buf *bytes.Buffer, fragSize int) (err error) {
 	fullPayload := packet.DATA
 	off := 0