feat: add udp handler

app/tun/config.pb.go

@@ -7,6 +7,7 @@
 package tun
 
 import (
+	packetaddr "github.com/v2fly/v2ray-core/v5/common/net/packetaddr"
 	_ "github.com/v2fly/v2ray-core/v5/common/protoext"
 	protoreflect "google.golang.org/protobuf/reflect/protoreflect"
 	protoimpl "google.golang.org/protobuf/runtime/protoimpl"
@@ -26,9 +27,10 @@ type Config struct {
 	sizeCache     protoimpl.SizeCache
 	unknownFields protoimpl.UnknownFields
 
-	Name      string `protobuf:"bytes,1,opt,name=name,proto3" json:"name,omitempty"`
-	Mtu       uint32 `protobuf:"varint,2,opt,name=mtu,proto3" json:"mtu,omitempty"`
-	UserLevel uint32 `protobuf:"varint,3,opt,name=user_level,json=userLevel,proto3" json:"user_level,omitempty"`
+	Name           string                    `protobuf:"bytes,1,opt,name=name,proto3" json:"name,omitempty"`
+	Mtu            uint32                    `protobuf:"varint,2,opt,name=mtu,proto3" json:"mtu,omitempty"`
+	UserLevel      uint32                    `protobuf:"varint,3,opt,name=user_level,json=userLevel,proto3" json:"user_level,omitempty"`
+	PacketEncoding packetaddr.PacketAddrType `protobuf:"varint,4,opt,name=packet_encoding,json=packetEncoding,proto3,enum=v2ray.core.net.packetaddr.PacketAddrType" json:"packet_encoding,omitempty"`
 }
 
 func (x *Config) Reset() {
@@ -84,26 +86,41 @@ func (x *Config) GetUserLevel() uint32 {
 	return 0
 }
 
+func (x *Config) GetPacketEncoding() packetaddr.PacketAddrType {
+	if x != nil {
+		return x.PacketEncoding
+	}
+	return packetaddr.PacketAddrType(0)
+}
+
 var File_app_tun_config_proto protoreflect.FileDescriptor
 
 var file_app_tun_config_proto_rawDesc = []byte{
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 }
 
 var (
@@ -120,14 +137,16 @@ func file_app_tun_config_proto_rawDescGZIP() []byte {
 
 var file_app_tun_config_proto_msgTypes = make([]protoimpl.MessageInfo, 1)
 var file_app_tun_config_proto_goTypes = []interface{}{
-	(*Config)(nil), // 0: v2ray.core.app.tun.Config
+	(*Config)(nil),                 // 0: v2ray.core.app.tun.Config
+	(packetaddr.PacketAddrType)(0), // 1: v2ray.core.net.packetaddr.PacketAddrType
 }
 var file_app_tun_config_proto_depIdxs = []int32{
-	0, // [0:0] is the sub-list for method output_type
-	0, // [0:0] is the sub-list for method input_type
-	0, // [0:0] is the sub-list for extension type_name
-	0, // [0:0] is the sub-list for extension extendee
-	0, // [0:0] is the sub-list for field type_name
+	1, // 0: v2ray.core.app.tun.Config.packet_encoding:type_name -> v2ray.core.net.packetaddr.PacketAddrType
+	1, // [1:1] is the sub-list for method output_type
+	1, // [1:1] is the sub-list for method input_type
+	1, // [1:1] is the sub-list for extension type_name
+	1, // [1:1] is the sub-list for extension extendee
+	0, // [0:1] is the sub-list for field type_name
 }
 
 func init() { file_app_tun_config_proto_init() }

app/tun/config.proto

@@ -8,7 +8,7 @@ option java_multiple_files = true;
 
 
 // import "app/router/routercommon/common.proto";
-
+import "common/net/packetaddr/config.proto";
 import "common/protoext/extensions.proto";
 
 message Config {
@@ -19,4 +19,5 @@ message Config {
     string name = 1;
     uint32 mtu = 2;
     uint32 user_level = 3;
+    v2ray.core.net.packetaddr.PacketAddrType packet_encoding = 4;
 }

app/tun/handler_udp.go

@@ -0,0 +1,89 @@
+package tun
+
+import (
+	"context"
+
+	"github.com/v2fly/v2ray-core/v5/common/buf"
+	"github.com/v2fly/v2ray-core/v5/common/net"
+	"github.com/v2fly/v2ray-core/v5/common/net/packetaddr"
+	udp_proto "github.com/v2fly/v2ray-core/v5/common/protocol/udp"
+	"github.com/v2fly/v2ray-core/v5/features/policy"
+	"github.com/v2fly/v2ray-core/v5/features/routing"
+	"github.com/v2fly/v2ray-core/v5/transport/internet/udp"
+	"gvisor.dev/gvisor/pkg/tcpip/adapters/gonet"
+	"gvisor.dev/gvisor/pkg/tcpip/stack"
+	gvisor_udp "gvisor.dev/gvisor/pkg/tcpip/transport/udp"
+	"gvisor.dev/gvisor/pkg/waiter"
+)
+
+type UDPHandler struct {
+	ctx           context.Context
+	dispatcher    routing.Dispatcher
+	policyManager policy.Manager
+	config        *Config
+
+	stack *stack.Stack
+}
+
+func SetUDPHandler(ctx context.Context, dispatcher routing.Dispatcher, policyManager policy.Manager, config *Config) StackOption {
+	return func(s *stack.Stack) error {
+		udpForwarder := gvisor_udp.NewForwarder(s, func(r *gvisor_udp.ForwarderRequest) {
+			wg := new(waiter.Queue)
+			linkedEndpoint, err := r.CreateEndpoint(wg)
+			if err != nil {
+				// TODO: log
+				return
+			}
+
+			udpConn := gonet.NewUDPConn(s, wg, linkedEndpoint)
+			udpHandler := &UDPHandler{
+				ctx:           ctx,
+				dispatcher:    dispatcher,
+				policyManager: policyManager,
+				config:        config,
+				stack:         s,
+			}
+			udpHandler.Handle(udpConn)
+		})
+		s.SetTransportProtocolHandler(gvisor_udp.ProtocolNumber, udpForwarder.HandlePacket)
+		return nil
+	}
+}
+func (h *UDPHandler) Handle(conn net.Conn) error {
+	ctx := h.ctx
+	packetConn := conn.(net.PacketConn)
+
+	udpDispatcherConstructor := udp.NewSplitDispatcher
+	switch h.config.PacketEncoding {
+	case packetaddr.PacketAddrType_None:
+		break
+	case packetaddr.PacketAddrType_Packet:
+		packetAddrDispatcherFactory := udp.NewPacketAddrDispatcherCreator(ctx)
+		udpDispatcherConstructor = packetAddrDispatcherFactory.NewPacketAddrDispatcher
+	}
+
+	udpServer := udpDispatcherConstructor(h.dispatcher, func(ctx context.Context, packet *udp_proto.Packet) {
+		if _, err := packetConn.WriteTo(packet.Payload.Bytes(), &net.UDPAddr{
+			IP:   packet.Source.Address.IP(),
+			Port: int(packet.Source.Port),
+		}); err != nil {
+			newError("failed to write UDP packet").Base(err).WriteToLog()
+		}
+	})
+
+	for {
+		select {
+		case <-ctx.Done():
+			return nil
+		default:
+			var buffer [2048]byte
+			n, addr, err := packetConn.ReadFrom(buffer[:])
+			if err != nil {
+				return newError("failed to read UDP packet").Base(err)
+			}
+			currentPacketCtx := ctx
+
+			udpServer.Dispatch(currentPacketCtx, net.DestinationFromAddr(addr), buf.FromBytes(buffer[:n]))
+		}
+	}
+}

app/tun/stack.go

@@ -30,6 +30,7 @@ func (t *TUN) CreateStack(linkedEndpoint stack.LinkEndpoint) (*stack.Stack, erro
 
 	opts := []StackOption{
 		SetTCPHandler(t.ctx, t.dispatcher, t.policyManager, t.config),
+		SetUDPHandler(t.ctx, t.dispatcher, t.policyManager, t.config),
 
 		CreateNIC(nicID, linkedEndpoint),
 	}