Objects implementation refactor

Refactored obj.go to a more generic approach
Added object support for already implemented expressions
Added test for limit object
Fixes https://github.com/google/nftables/issues/253

counter.go

@@ -16,11 +16,11 @@ package nftables
 
 import (
 	"github.com/google/nftables/binaryutil"
+	"github.com/google/nftables/expr"
 	"github.com/mdlayher/netlink"
 	"golang.org/x/sys/unix"
 )
 
-// CounterObj implements Obj.
 type CounterObj struct {
 	Table *Table
 	Name  string // e.g. “fwded”
@@ -41,6 +41,20 @@ func (c *CounterObj) unmarshal(ad *netlink.AttributeDecoder) error {
 	return ad.Err()
 }
 
+func (c *CounterObj) data() expr.Any {
+	return &expr.Counter{
+		Bytes:   c.Bytes,
+		Packets: c.Packets,
+	}
+}
+
+func (c *CounterObj) name() string {
+	return c.Name
+}
+func (c *CounterObj) objType() ObjType {
+	return ObjTypeCounter
+}
+
 func (c *CounterObj) table() *Table {
 	return c.Table
 }

expr/bitwise.go

@@ -31,6 +31,17 @@ type Bitwise struct {
 }
 
 func (e *Bitwise) marshal(fam byte) ([]byte, error) {
+	data, err := e.marshalData(fam)
+	if err != nil {
+		return nil, err
+	}
+	return netlink.MarshalAttributes([]netlink.Attribute{
+		{Type: unix.NFTA_EXPR_NAME, Data: []byte("bitwise\x00")},
+		{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: data},
+	})
+}
+
+func (e *Bitwise) marshalData(fam byte) ([]byte, error) {
 	mask, err := netlink.MarshalAttributes([]netlink.Attribute{
 		{Type: unix.NFTA_DATA_VALUE, Data: e.Mask},
 	})
@@ -44,20 +55,13 @@ func (e *Bitwise) marshal(fam byte) ([]byte, error) {
 		return nil, err
 	}
 
-	data, err := netlink.MarshalAttributes([]netlink.Attribute{
+	return netlink.MarshalAttributes([]netlink.Attribute{
 		{Type: unix.NFTA_BITWISE_SREG, Data: binaryutil.BigEndian.PutUint32(e.SourceRegister)},
 		{Type: unix.NFTA_BITWISE_DREG, Data: binaryutil.BigEndian.PutUint32(e.DestRegister)},
 		{Type: unix.NFTA_BITWISE_LEN, Data: binaryutil.BigEndian.PutUint32(e.Len)},
 		{Type: unix.NLA_F_NESTED | unix.NFTA_BITWISE_MASK, Data: mask},
 		{Type: unix.NLA_F_NESTED | unix.NFTA_BITWISE_XOR, Data: xor},
 	})
-	if err != nil {
-		return nil, err
-	}
-	return netlink.MarshalAttributes([]netlink.Attribute{
-		{Type: unix.NFTA_EXPR_NAME, Data: []byte("bitwise\x00")},
-		{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: data},
-	})
 }
 
 func (e *Bitwise) unmarshal(fam byte, data []byte) error {

expr/byteorder.go

@@ -38,13 +38,7 @@ type Byteorder struct {
 }
 
 func (e *Byteorder) marshal(fam byte) ([]byte, error) {
-	data, err := netlink.MarshalAttributes([]netlink.Attribute{
+	data, err := e.marshalData(fam)
-		{Type: unix.NFTA_BYTEORDER_SREG, Data: binaryutil.BigEndian.PutUint32(e.SourceRegister)},
-		{Type: unix.NFTA_BYTEORDER_DREG, Data: binaryutil.BigEndian.PutUint32(e.DestRegister)},
-		{Type: unix.NFTA_BYTEORDER_OP, Data: binaryutil.BigEndian.PutUint32(uint32(e.Op))},
-		{Type: unix.NFTA_BYTEORDER_LEN, Data: binaryutil.BigEndian.PutUint32(e.Len)},
-		{Type: unix.NFTA_BYTEORDER_SIZE, Data: binaryutil.BigEndian.PutUint32(e.Size)},
-	})
 	if err != nil {
 		return nil, err
 	}
@@ -54,6 +48,16 @@ func (e *Byteorder) marshal(fam byte) ([]byte, error) {
 	})
 }
 
+func (e *Byteorder) marshalData(fam byte) ([]byte, error) {
+	return netlink.MarshalAttributes([]netlink.Attribute{
+		{Type: unix.NFTA_BYTEORDER_SREG, Data: binaryutil.BigEndian.PutUint32(e.SourceRegister)},
+		{Type: unix.NFTA_BYTEORDER_DREG, Data: binaryutil.BigEndian.PutUint32(e.DestRegister)},
+		{Type: unix.NFTA_BYTEORDER_OP, Data: binaryutil.BigEndian.PutUint32(uint32(e.Op))},
+		{Type: unix.NFTA_BYTEORDER_LEN, Data: binaryutil.BigEndian.PutUint32(e.Len)},
+		{Type: unix.NFTA_BYTEORDER_SIZE, Data: binaryutil.BigEndian.PutUint32(e.Size)},
+	})
+}
+
 func (e *Byteorder) unmarshal(fam byte, data []byte) error {
 	return fmt.Errorf("not yet implemented")
 }

expr/connlimit.go

@@ -37,10 +37,7 @@ type Connlimit struct {
 }
 
 func (e *Connlimit) marshal(fam byte) ([]byte, error) {
-	data, err := netlink.MarshalAttributes([]netlink.Attribute{
+	data, err := e.marshalData(fam)
-		{Type: NFTA_CONNLIMIT_COUNT, Data: binaryutil.BigEndian.PutUint32(e.Count)},
-		{Type: NFTA_CONNLIMIT_FLAGS, Data: binaryutil.BigEndian.PutUint32(e.Flags)},
-	})
 	if err != nil {
 		return nil, err
 	}
@@ -51,6 +48,13 @@ func (e *Connlimit) marshal(fam byte) ([]byte, error) {
 	})
 }
 
+func (e *Connlimit) marshalData(fam byte) ([]byte, error) {
+	return netlink.MarshalAttributes([]netlink.Attribute{
+		{Type: NFTA_CONNLIMIT_COUNT, Data: binaryutil.BigEndian.PutUint32(e.Count)},
+		{Type: NFTA_CONNLIMIT_FLAGS, Data: binaryutil.BigEndian.PutUint32(e.Flags)},
+	})
+}
+
 func (e *Connlimit) unmarshal(fam byte, data []byte) error {
 	ad, err := netlink.NewAttributeDecoder(data)
 	if err != nil {

expr/counter.go

@@ -28,10 +28,7 @@ type Counter struct {
 }
 
 func (e *Counter) marshal(fam byte) ([]byte, error) {
-	data, err := netlink.MarshalAttributes([]netlink.Attribute{
+	data, err := e.marshalData(fam)
-		{Type: unix.NFTA_COUNTER_BYTES, Data: binaryutil.BigEndian.PutUint64(e.Bytes)},
-		{Type: unix.NFTA_COUNTER_PACKETS, Data: binaryutil.BigEndian.PutUint64(e.Packets)},
-	})
 	if err != nil {
 		return nil, err
 	}
@@ -42,6 +39,13 @@ func (e *Counter) marshal(fam byte) ([]byte, error) {
 	})
 }
 
+func (e *Counter) marshalData(fam byte) ([]byte, error) {
+	return netlink.MarshalAttributes([]netlink.Attribute{
+		{Type: unix.NFTA_COUNTER_BYTES, Data: binaryutil.BigEndian.PutUint64(e.Bytes)},
+		{Type: unix.NFTA_COUNTER_PACKETS, Data: binaryutil.BigEndian.PutUint64(e.Packets)},
+	})
+}
+
 func (e *Counter) unmarshal(fam byte, data []byte) error {
 	ad, err := netlink.NewAttributeDecoder(data)
 	if err != nil {

expr/ct.go

@@ -64,7 +64,19 @@ type Ct struct {
 }
 
 func (e *Ct) marshal(fam byte) ([]byte, error) {
-	regData := []byte{}
+	exprData, err := e.marshalData(fam)
+	if err != nil {
+		return nil, err
+	}
+
+	return netlink.MarshalAttributes([]netlink.Attribute{
+		{Type: unix.NFTA_EXPR_NAME, Data: []byte("ct\x00")},
+		{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: exprData},
+	})
+}
+
+func (e *Ct) marshalData(fam byte) ([]byte, error) {
+	var regData []byte
 	exprData, err := netlink.MarshalAttributes(
 		[]netlink.Attribute{
 			{Type: unix.NFTA_CT_KEY, Data: binaryutil.BigEndian.PutUint32(uint32(e.Key))},
@@ -90,11 +102,7 @@ func (e *Ct) marshal(fam byte) ([]byte, error) {
 		return nil, err
 	}
 	exprData = append(exprData, regData...)
-
+	return exprData, nil
-	return netlink.MarshalAttributes([]netlink.Attribute{
-		{Type: unix.NFTA_EXPR_NAME, Data: []byte("ct\x00")},
-		{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: exprData},
-	})
 }
 
 func (e *Ct) unmarshal(fam byte, data []byte) error {

expr/dup.go

@@ -29,16 +29,7 @@ type Dup struct {
 }
 
 func (e *Dup) marshal(fam byte) ([]byte, error) {
-	attrs := []netlink.Attribute{
+	data, err := e.marshalData(fam)
-		{Type: unix.NFTA_DUP_SREG_ADDR, Data: binaryutil.BigEndian.PutUint32(e.RegAddr)},
-	}
-
-	if e.IsRegDevSet {
-		attrs = append(attrs, netlink.Attribute{Type: unix.NFTA_DUP_SREG_DEV, Data: binaryutil.BigEndian.PutUint32(e.RegDev)})
-	}
-
-	data, err := netlink.MarshalAttributes(attrs)
-
 	if err != nil {
 		return nil, err
 	}
@@ -49,6 +40,18 @@ func (e *Dup) marshal(fam byte) ([]byte, error) {
 	})
 }
 
+func (e *Dup) marshalData(fam byte) ([]byte, error) {
+	attrs := []netlink.Attribute{
+		{Type: unix.NFTA_DUP_SREG_ADDR, Data: binaryutil.BigEndian.PutUint32(e.RegAddr)},
+	}
+
+	if e.IsRegDevSet {
+		attrs = append(attrs, netlink.Attribute{Type: unix.NFTA_DUP_SREG_DEV, Data: binaryutil.BigEndian.PutUint32(e.RegDev)})
+	}
+
+	return netlink.MarshalAttributes(attrs)
+}
+
 func (e *Dup) unmarshal(fam byte, data []byte) error {
 	ad, err := netlink.NewAttributeDecoder(data)
 	if err != nil {

expr/dynset.go

@@ -44,6 +44,18 @@ type Dynset struct {
 }
 
 func (e *Dynset) marshal(fam byte) ([]byte, error) {
+	opData, err := e.marshalData(fam)
+	if err != nil {
+		return nil, err
+	}
+
+	return netlink.MarshalAttributes([]netlink.Attribute{
+		{Type: unix.NFTA_EXPR_NAME, Data: []byte("dynset\x00")},
+		{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: opData},
+	})
+}
+
+func (e *Dynset) marshalData(fam byte) ([]byte, error) {
 	// See: https://git.netfilter.org/libnftnl/tree/src/expr/dynset.c
 	var opAttrs []netlink.Attribute
 	opAttrs = append(opAttrs, netlink.Attribute{Type: unix.NFTA_DYNSET_SREG_KEY, Data: binaryutil.BigEndian.PutUint32(e.SrcRegKey)})
@@ -89,17 +101,9 @@ func (e *Dynset) marshal(fam byte) ([]byte, error) {
 			opAttrs = append(opAttrs, netlink.Attribute{Type: NFTA_DYNSET_EXPRESSIONS, Data: elemData})
 		}
 	}
+
 	opAttrs = append(opAttrs, netlink.Attribute{Type: unix.NFTA_DYNSET_FLAGS, Data: binaryutil.BigEndian.PutUint32(flags)})
-
+	return netlink.MarshalAttributes(opAttrs)
-	opData, err := netlink.MarshalAttributes(opAttrs)
-	if err != nil {
-		return nil, err
-	}
-
-	return netlink.MarshalAttributes([]netlink.Attribute{
-		{Type: unix.NFTA_EXPR_NAME, Data: []byte("dynset\x00")},
-		{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: opData},
-	})
 }
 
 func (e *Dynset) unmarshal(fam byte, data []byte) error {
@@ -125,7 +129,7 @@ func (e *Dynset) unmarshal(fam byte, data []byte) error {
 		case unix.NFTA_DYNSET_FLAGS:
 			e.Invert = (ad.Uint32() & unix.NFT_DYNSET_F_INV) != 0
 		case unix.NFTA_DYNSET_EXPR:
-			exprs, err := parseexprfunc.ParseExprBytesFunc(fam, ad, ad.Bytes())
+			exprs, err := parseexprfunc.ParseExprBytesFunc(fam, ad)
 			if err != nil {
 				return err
 			}

expr/expr.go

@@ -25,8 +25,8 @@ import (
 )
 
 func init() {
-	parseexprfunc.ParseExprBytesFunc = func(fam byte, ad *netlink.AttributeDecoder, b []byte) ([]interface{}, error) {
+	parseexprfunc.ParseExprBytesFunc = func(fam byte, ad *netlink.AttributeDecoder, args ...string) ([]interface{}, error) {
-		exprs, err := exprsFromBytes(fam, ad, b)
+		exprs, err := exprsFromBytes(fam, ad, args...)
 		if err != nil {
 			return nil, err
 		}
@@ -36,7 +36,7 @@ func init() {
 		}
 		return result, nil
 	}
-	parseexprfunc.ParseExprMsgFunc = func(fam byte, b []byte) ([]interface{}, error) {
+	parseexprfunc.ParseExprMsgFunc = func(fam byte, b []byte, args ...string) ([]interface{}, error) {
 		ad, err := netlink.NewAttributeDecoder(b)
 		if err != nil {
 			return nil, err
@@ -44,7 +44,7 @@ func init() {
 		ad.ByteOrder = binary.BigEndian
 		var exprs []interface{}
 		for ad.Next() {
-			e, err := parseexprfunc.ParseExprBytesFunc(fam, ad, b)
+			e, err := parseexprfunc.ParseExprBytesFunc(fam, ad, args...)
 			if err != nil {
 				return e, err
 			}
@@ -59,6 +59,10 @@ func Marshal(fam byte, e Any) ([]byte, error) {
 	return e.marshal(fam)
 }
 
+func MarshalExprData(fam byte, e Any) ([]byte, error) {
+	return e.marshalData(fam)
+}
+
 // Unmarshal fills an expression from the specified byte slice.
 func Unmarshal(fam byte, data []byte, e Any) error {
 	return e.unmarshal(fam, data)
@@ -66,8 +70,20 @@ func Unmarshal(fam byte, data []byte, e Any) error {
 
 // exprsFromBytes parses nested raw expressions bytes
 // to construct nftables expressions
-func exprsFromBytes(fam byte, ad *netlink.AttributeDecoder, b []byte) ([]Any, error) {
+func exprsFromBytes(fam byte, ad *netlink.AttributeDecoder, args ...string) ([]Any, error) {
 	var exprs []Any
+	if len(args) > 0 {
+		e := exprFromName(args[0])
+		ad.Do(func(b []byte) error {
+			if err := Unmarshal(fam, b, e); err != nil {
+				return err
+			}
+			exprs = append(exprs, e)
+			return nil
+		})
+		return exprs, ad.Err()
+	}
+
 	ad.Do(func(b []byte) error {
 		ad, err := netlink.NewAttributeDecoder(b)
 		if err != nil {
@@ -84,65 +100,12 @@ func exprsFromBytes(fam byte, ad *netlink.AttributeDecoder, b []byte) ([]Any, er
 					exprs = append(exprs, e)
 				}
 			case unix.NFTA_EXPR_DATA:
-				var e Any
+				e := exprFromName(name)
-				switch name {
-				case "ct":
-					e = &Ct{}
-				case "range":
-					e = &Range{}
-				case "meta":
-					e = &Meta{}
-				case "cmp":
-					e = &Cmp{}
-				case "counter":
-					e = &Counter{}
-				case "objref":
-					e = &Objref{}
-				case "payload":
-					e = &Payload{}
-				case "lookup":
-					e = &Lookup{}
-				case "immediate":
-					e = &Immediate{}
-				case "bitwise":
-					e = &Bitwise{}
-				case "redir":
-					e = &Redir{}
-				case "nat":
-					e = &NAT{}
-				case "limit":
-					e = &Limit{}
-				case "quota":
-					e = &Quota{}
-				case "dynset":
-					e = &Dynset{}
-				case "log":
-					e = &Log{}
-				case "exthdr":
-					e = &Exthdr{}
-				case "match":
-					e = &Match{}
-				case "target":
-					e = &Target{}
-				case "connlimit":
-					e = &Connlimit{}
-				case "queue":
-					e = &Queue{}
-				case "flow_offload":
-					e = &FlowOffload{}
-				case "reject":
-					e = &Reject{}
-				case "masq":
-					e = &Masq{}
-				case "hash":
-					e = &Hash{}
-				}
 				if e == nil {
 					// TODO: introduce an opaque expression type so that users know
 					// something is here.
 					continue // unsupported expression type
 				}
-
 				ad.Do(func(b []byte) error {
 					if err := Unmarshal(fam, b, e); err != nil {
 						return err
@@ -166,9 +129,67 @@ func exprsFromBytes(fam byte, ad *netlink.AttributeDecoder, b []byte) ([]Any, er
 	return exprs, ad.Err()
 }
 
+func exprFromName(name string) Any {
+	var e Any
+	switch name {
+	case "ct":
+		e = &Ct{}
+	case "range":
+		e = &Range{}
+	case "meta":
+		e = &Meta{}
+	case "cmp":
+		e = &Cmp{}
+	case "counter":
+		e = &Counter{}
+	case "objref":
+		e = &Objref{}
+	case "payload":
+		e = &Payload{}
+	case "lookup":
+		e = &Lookup{}
+	case "immediate":
+		e = &Immediate{}
+	case "bitwise":
+		e = &Bitwise{}
+	case "redir":
+		e = &Redir{}
+	case "nat":
+		e = &NAT{}
+	case "limit":
+		e = &Limit{}
+	case "quota":
+		e = &Quota{}
+	case "dynset":
+		e = &Dynset{}
+	case "log":
+		e = &Log{}
+	case "exthdr":
+		e = &Exthdr{}
+	case "match":
+		e = &Match{}
+	case "target":
+		e = &Target{}
+	case "connlimit":
+		e = &Connlimit{}
+	case "queue":
+		e = &Queue{}
+	case "flow_offload":
+		e = &FlowOffload{}
+	case "reject":
+		e = &Reject{}
+	case "masq":
+		e = &Masq{}
+	case "hash":
+		e = &Hash{}
+	}
+	return e
+}
+
 // Any is an interface implemented by any expression type.
 type Any interface {
 	marshal(fam byte) ([]byte, error)
+	marshalData(fam byte) ([]byte, error)
 	unmarshal(fam byte, data []byte) error
 }
 
@@ -214,7 +235,19 @@ type Meta struct {
 }
 
 func (e *Meta) marshal(fam byte) ([]byte, error) {
-	regData := []byte{}
+	exprData, err := e.marshalData(fam)
+	if err != nil {
+		return nil, err
+	}
+
+	return netlink.MarshalAttributes([]netlink.Attribute{
+		{Type: unix.NFTA_EXPR_NAME, Data: []byte("meta\x00")},
+		{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: exprData},
+	})
+}
+
+func (e *Meta) marshalData(fam byte) ([]byte, error) {
+	var regData []byte
 	exprData, err := netlink.MarshalAttributes(
 		[]netlink.Attribute{
 			{Type: unix.NFTA_META_KEY, Data: binaryutil.BigEndian.PutUint32(uint32(e.Key))},
@@ -240,11 +273,7 @@ func (e *Meta) marshal(fam byte) ([]byte, error) {
 		return nil, err
 	}
 	exprData = append(exprData, regData...)
-
+	return exprData, nil
-	return netlink.MarshalAttributes([]netlink.Attribute{
-		{Type: unix.NFTA_EXPR_NAME, Data: []byte("meta\x00")},
-		{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: exprData},
-	})
 }
 
 func (e *Meta) unmarshal(fam byte, data []byte) error {
@@ -291,6 +320,17 @@ const (
 )
 
 func (e *Masq) marshal(fam byte) ([]byte, error) {
+	msgData, err := e.marshalData(fam)
+	if err != nil {
+		return nil, err
+	}
+	return netlink.MarshalAttributes([]netlink.Attribute{
+		{Type: unix.NFTA_EXPR_NAME, Data: []byte("masq\x00")},
+		{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: msgData},
+	})
+}
+
+func (e *Masq) marshalData(fam byte) ([]byte, error) {
 	msgData := []byte{}
 	if !e.ToPorts {
 		flags := uint32(0)
@@ -327,10 +367,7 @@ func (e *Masq) marshal(fam byte) ([]byte, error) {
 			msgData = append(msgData, regsData...)
 		}
 	}
-	return netlink.MarshalAttributes([]netlink.Attribute{
+	return msgData, nil
-		{Type: unix.NFTA_EXPR_NAME, Data: []byte("masq\x00")},
-		{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: msgData},
-	})
 }
 
 func (e *Masq) unmarshal(fam byte, data []byte) error {
@@ -377,17 +414,7 @@ type Cmp struct {
 }
 
 func (e *Cmp) marshal(fam byte) ([]byte, error) {
-	cmpData, err := netlink.MarshalAttributes([]netlink.Attribute{
+	exprData, err := e.marshalData(fam)
-		{Type: unix.NFTA_DATA_VALUE, Data: e.Data},
-	})
-	if err != nil {
-		return nil, err
-	}
-	exprData, err := netlink.MarshalAttributes([]netlink.Attribute{
-		{Type: unix.NFTA_CMP_SREG, Data: binaryutil.BigEndian.PutUint32(e.Register)},
-		{Type: unix.NFTA_CMP_OP, Data: binaryutil.BigEndian.PutUint32(uint32(e.Op))},
-		{Type: unix.NLA_F_NESTED | unix.NFTA_CMP_DATA, Data: cmpData},
-	})
 	if err != nil {
 		return nil, err
 	}
@@ -397,6 +424,20 @@ func (e *Cmp) marshal(fam byte) ([]byte, error) {
 	})
 }
 
+func (e *Cmp) marshalData(fam byte) ([]byte, error) {
+	cmpData, err := netlink.MarshalAttributes([]netlink.Attribute{
+		{Type: unix.NFTA_DATA_VALUE, Data: e.Data},
+	})
+	if err != nil {
+		return nil, err
+	}
+	return netlink.MarshalAttributes([]netlink.Attribute{
+		{Type: unix.NFTA_CMP_SREG, Data: binaryutil.BigEndian.PutUint32(e.Register)},
+		{Type: unix.NFTA_CMP_OP, Data: binaryutil.BigEndian.PutUint32(uint32(e.Op))},
+		{Type: unix.NLA_F_NESTED | unix.NFTA_CMP_DATA, Data: cmpData},
+	})
+}
+
 func (e *Cmp) unmarshal(fam byte, data []byte) error {
 	ad, err := netlink.NewAttributeDecoder(data)
 	if err != nil {

expr/exthdr.go

@@ -40,6 +40,17 @@ type Exthdr struct {
 }
 
 func (e *Exthdr) marshal(fam byte) ([]byte, error) {
+	data, err := e.marshalData(fam)
+	if err != nil {
+		return nil, err
+	}
+	return netlink.MarshalAttributes([]netlink.Attribute{
+		{Type: unix.NFTA_EXPR_NAME, Data: []byte("exthdr\x00")},
+		{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: data},
+	})
+}
+
+func (e *Exthdr) marshalData(fam byte) ([]byte, error) {
 	var attr []netlink.Attribute
 
 	// Operations are differentiated by the Op and whether the SourceRegister
@@ -64,14 +75,7 @@ func (e *Exthdr) marshal(fam byte) ([]byte, error) {
 			netlink.Attribute{Type: unix.NFTA_EXTHDR_FLAGS, Data: binaryutil.BigEndian.PutUint32(e.Flags)})
 	}
 
-	data, err := netlink.MarshalAttributes(attr)
+	return netlink.MarshalAttributes(attr)
-	if err != nil {
-		return nil, err
-	}
-	return netlink.MarshalAttributes([]netlink.Attribute{
-		{Type: unix.NFTA_EXPR_NAME, Data: []byte("exthdr\x00")},
-		{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: data},
-	})
 }
 
 func (e *Exthdr) unmarshal(fam byte, data []byte) error {

expr/fib.go

@@ -37,6 +37,17 @@ type Fib struct {
 }
 
 func (e *Fib) marshal(fam byte) ([]byte, error) {
+	data, err := e.marshalData(fam)
+	if err != nil {
+		return nil, err
+	}
+	return netlink.MarshalAttributes([]netlink.Attribute{
+		{Type: unix.NFTA_EXPR_NAME, Data: []byte("fib\x00")},
+		{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: data},
+	})
+}
+
+func (e *Fib) marshalData(fam byte) ([]byte, error) {
 	data := []byte{}
 	reg, err := netlink.MarshalAttributes([]netlink.Attribute{
 		{Type: unix.NFTA_FIB_DREG, Data: binaryutil.BigEndian.PutUint32(e.Register)},
@@ -92,11 +103,7 @@ func (e *Fib) marshal(fam byte) ([]byte, error) {
 		}
 		data = append(data, rslt...)
 	}
-
+	return data, nil
-	return netlink.MarshalAttributes([]netlink.Attribute{
-		{Type: unix.NFTA_EXPR_NAME, Data: []byte("fib\x00")},
-		{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: data},
-	})
 }
 
 func (e *Fib) unmarshal(fam byte, data []byte) error {

expr/flow_offload.go

@@ -28,9 +28,7 @@ type FlowOffload struct {
 }
 
 func (e *FlowOffload) marshal(fam byte) ([]byte, error) {
-	data, err := netlink.MarshalAttributes([]netlink.Attribute{
+	data, err := e.marshalData(fam)
-		{Type: NFTNL_EXPR_FLOW_TABLE_NAME, Data: []byte(e.Name)},
-	})
 	if err != nil {
 		return nil, err
 	}
@@ -41,6 +39,12 @@ func (e *FlowOffload) marshal(fam byte) ([]byte, error) {
 	})
 }
 
+func (e *FlowOffload) marshalData(fam byte) ([]byte, error) {
+	return netlink.MarshalAttributes([]netlink.Attribute{
+		{Type: NFTNL_EXPR_FLOW_TABLE_NAME, Data: []byte(e.Name)},
+	})
+}
+
 func (e *FlowOffload) unmarshal(fam byte, data []byte) error {
 	ad, err := netlink.NewAttributeDecoder(data)
 	if err != nil {

expr/hash.go

@@ -41,6 +41,17 @@ type Hash struct {
 }
 
 func (e *Hash) marshal(fam byte) ([]byte, error) {
+	data, err := e.marshalData(fam)
+	if err != nil {
+		return nil, err
+	}
+	return netlink.MarshalAttributes([]netlink.Attribute{
+		{Type: unix.NFTA_EXPR_NAME, Data: []byte("hash\x00")},
+		{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: data},
+	})
+}
+
+func (e *Hash) marshalData(fam byte) ([]byte, error) {
 	hashAttrs := []netlink.Attribute{
 		{Type: unix.NFTA_HASH_SREG, Data: binaryutil.BigEndian.PutUint32(uint32(e.SourceRegister))},
 		{Type: unix.NFTA_HASH_DREG, Data: binaryutil.BigEndian.PutUint32(uint32(e.DestRegister))},
@@ -56,14 +67,7 @@ func (e *Hash) marshal(fam byte) ([]byte, error) {
 		{Type: unix.NFTA_HASH_OFFSET, Data: binaryutil.BigEndian.PutUint32(uint32(e.Offset))},
 		{Type: unix.NFTA_HASH_TYPE, Data: binaryutil.BigEndian.PutUint32(uint32(e.Type))},
 	}...)
-	data, err := netlink.MarshalAttributes(hashAttrs)
+	return netlink.MarshalAttributes(hashAttrs)
-	if err != nil {
-		return nil, err
-	}
-	return netlink.MarshalAttributes([]netlink.Attribute{
-		{Type: unix.NFTA_EXPR_NAME, Data: []byte("hash\x00")},
-		{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: data},
-	})
 }
 
 func (e *Hash) unmarshal(fam byte, data []byte) error {

expr/immediate.go

@@ -29,6 +29,17 @@ type Immediate struct {
 }
 
 func (e *Immediate) marshal(fam byte) ([]byte, error) {
+	data, err := e.marshalData(fam)
+	if err != nil {
+		return nil, err
+	}
+	return netlink.MarshalAttributes([]netlink.Attribute{
+		{Type: unix.NFTA_EXPR_NAME, Data: []byte("immediate\x00")},
+		{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: data},
+	})
+}
+
+func (e *Immediate) marshalData(fam byte) ([]byte, error) {
 	immData, err := netlink.MarshalAttributes([]netlink.Attribute{
 		{Type: unix.NFTA_DATA_VALUE, Data: e.Data},
 	})
@@ -36,17 +47,10 @@ func (e *Immediate) marshal(fam byte) ([]byte, error) {
 		return nil, err
 	}
 
-	data, err := netlink.MarshalAttributes([]netlink.Attribute{
+	return netlink.MarshalAttributes([]netlink.Attribute{
 		{Type: unix.NFTA_IMMEDIATE_DREG, Data: binaryutil.BigEndian.PutUint32(e.Register)},
 		{Type: unix.NLA_F_NESTED | unix.NFTA_IMMEDIATE_DATA, Data: immData},
 	})
-	if err != nil {
-		return nil, err
-	}
-	return netlink.MarshalAttributes([]netlink.Attribute{
-		{Type: unix.NFTA_EXPR_NAME, Data: []byte("immediate\x00")},
-		{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: data},
-	})
 }
 
 func (e *Immediate) unmarshal(fam byte, data []byte) error {

expr/limit.go

@@ -72,6 +72,18 @@ type Limit struct {
 }
 
 func (l *Limit) marshal(fam byte) ([]byte, error) {
+	data, err := l.marshalData(fam)
+	if err != nil {
+		return nil, err
+	}
+
+	return netlink.MarshalAttributes([]netlink.Attribute{
+		{Type: unix.NFTA_EXPR_NAME, Data: []byte("limit\x00")},
+		{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: data},
+	})
+}
+
+func (l *Limit) marshalData(fam byte) ([]byte, error) {
 	var flags uint32
 	if l.Over {
 		flags = unix.NFT_LIMIT_F_INV
@@ -84,15 +96,7 @@ func (l *Limit) marshal(fam byte) ([]byte, error) {
 		{Type: unix.NFTA_LIMIT_FLAGS, Data: binaryutil.BigEndian.PutUint32(flags)},
 	}
 
-	data, err := netlink.MarshalAttributes(attrs)
+	return netlink.MarshalAttributes(attrs)
-	if err != nil {
-		return nil, err
-	}
-
-	return netlink.MarshalAttributes([]netlink.Attribute{
-		{Type: unix.NFTA_EXPR_NAME, Data: []byte("limit\x00")},
-		{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: data},
-	})
 }
 
 func (l *Limit) unmarshal(fam byte, data []byte) error {

expr/log.go

@@ -69,6 +69,18 @@ type Log struct {
 }
 
 func (e *Log) marshal(fam byte) ([]byte, error) {
+	data, err := e.marshalData(fam)
+	if err != nil {
+		return nil, err
+	}
+
+	return netlink.MarshalAttributes([]netlink.Attribute{
+		{Type: unix.NFTA_EXPR_NAME, Data: []byte("log\x00")},
+		{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: data},
+	})
+}
+
+func (e *Log) marshalData(fam byte) ([]byte, error) {
 	// Per https://git.netfilter.org/libnftnl/tree/src/expr/log.c?id=09456c720e9c00eecc08e41ac6b7c291b3821ee5#n129
 	attrs := make([]netlink.Attribute, 0)
 	if e.Key&(1<<unix.NFTA_LOG_GROUP) != 0 {
@@ -109,15 +121,7 @@ func (e *Log) marshal(fam byte) ([]byte, error) {
 		})
 	}
 
-	data, err := netlink.MarshalAttributes(attrs)
+	return netlink.MarshalAttributes(attrs)
-	if err != nil {
-		return nil, err
-	}
-
-	return netlink.MarshalAttributes([]netlink.Attribute{
-		{Type: unix.NFTA_EXPR_NAME, Data: []byte("log\x00")},
-		{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: data},
-	})
 }
 
 func (e *Log) unmarshal(fam byte, data []byte) error {

expr/lookup.go

@@ -34,6 +34,18 @@ type Lookup struct {
 }
 
 func (e *Lookup) marshal(fam byte) ([]byte, error) {
+	opData, err := e.marshalData(fam)
+	if err != nil {
+		return nil, err
+	}
+
+	return netlink.MarshalAttributes([]netlink.Attribute{
+		{Type: unix.NFTA_EXPR_NAME, Data: []byte("lookup\x00")},
+		{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: opData},
+	})
+}
+
+func (e *Lookup) marshalData(fam byte) ([]byte, error) {
 	// See: https://git.netfilter.org/libnftnl/tree/src/expr/lookup.c?id=6dc1c3d8bb64077da7f3f28c7368fb087d10a492#n115
 	var opAttrs []netlink.Attribute
 	if e.SourceRegister != 0 {
@@ -49,15 +61,7 @@ func (e *Lookup) marshal(fam byte) ([]byte, error) {
 		netlink.Attribute{Type: unix.NFTA_LOOKUP_SET, Data: []byte(e.SetName + "\x00")},
 		netlink.Attribute{Type: unix.NFTA_LOOKUP_SET_ID, Data: binaryutil.BigEndian.PutUint32(e.SetID)},
 	)
-	opData, err := netlink.MarshalAttributes(opAttrs)
+	return netlink.MarshalAttributes(opAttrs)
-	if err != nil {
-		return nil, err
-	}
-
-	return netlink.MarshalAttributes([]netlink.Attribute{
-		{Type: unix.NFTA_EXPR_NAME, Data: []byte("lookup\x00")},
-		{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: opData},
-	})
 }
 
 func (e *Lookup) unmarshal(fam byte, data []byte) error {

expr/match.go

@@ -18,6 +18,17 @@ type Match struct {
 }
 
 func (e *Match) marshal(fam byte) ([]byte, error) {
+	data, err := e.marshalData(fam)
+	if err != nil {
+		return nil, err
+	}
+	return netlink.MarshalAttributes([]netlink.Attribute{
+		{Type: unix.NFTA_EXPR_NAME, Data: []byte("match\x00")},
+		{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: data},
+	})
+}
+
+func (e *Match) marshalData(fam byte) ([]byte, error) {
 	// Per https://git.netfilter.org/libnftnl/tree/src/expr/match.c?id=09456c720e9c00eecc08e41ac6b7c291b3821ee5#n38
 	name := e.Name
 	// limit the extension name as (some) user-space tools do and leave room for
@@ -36,15 +47,7 @@ func (e *Match) marshal(fam byte) ([]byte, error) {
 		{Type: unix.NFTA_MATCH_REV, Data: binaryutil.BigEndian.PutUint32(e.Rev)},
 		{Type: unix.NFTA_MATCH_INFO, Data: info},
 	}
-	data, err := netlink.MarshalAttributes(attrs)
+	return netlink.MarshalAttributes(attrs)
-	if err != nil {
-		return nil, err
-	}
-
-	return netlink.MarshalAttributes([]netlink.Attribute{
-		{Type: unix.NFTA_EXPR_NAME, Data: []byte("match\x00")},
-		{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: data},
-	})
 }
 
 func (e *Match) unmarshal(fam byte, data []byte) error {

expr/nat.go

@@ -57,6 +57,17 @@ type NAT struct {
 // | 00 00 00 02  |	|      data      |  reg 2
 
 func (e *NAT) marshal(fam byte) ([]byte, error) {
+	data, err := e.marshalData(fam)
+	if err != nil {
+		return nil, err
+	}
+	return netlink.MarshalAttributes([]netlink.Attribute{
+		{Type: unix.NFTA_EXPR_NAME, Data: []byte("nat\x00")},
+		{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: data},
+	})
+}
+
+func (e *NAT) marshalData(fam byte) ([]byte, error) {
 	attrs := []netlink.Attribute{
 		{Type: unix.NFTA_NAT_TYPE, Data: binaryutil.BigEndian.PutUint32(uint32(e.Type))},
 		{Type: unix.NFTA_NAT_FAMILY, Data: binaryutil.BigEndian.PutUint32(e.Family)},
@@ -90,14 +101,7 @@ func (e *NAT) marshal(fam byte) ([]byte, error) {
 		attrs = append(attrs, netlink.Attribute{Type: unix.NFTA_NAT_FLAGS, Data: binaryutil.BigEndian.PutUint32(flags)})
 	}
 
-	data, err := netlink.MarshalAttributes(attrs)
+	return netlink.MarshalAttributes(attrs)
-	if err != nil {
-		return nil, err
-	}
-	return netlink.MarshalAttributes([]netlink.Attribute{
-		{Type: unix.NFTA_EXPR_NAME, Data: []byte("nat\x00")},
-		{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: data},
-	})
 }
 
 func (e *NAT) unmarshal(fam byte, data []byte) error {

expr/notrack.go

@@ -27,6 +27,10 @@ func (e *Notrack) marshal(fam byte) ([]byte, error) {
 	})
 }
 
+func (e *Notrack) marshalData(fam byte) ([]byte, error) {
+	return []byte("notrack\x00"), nil
+}
+
 func (e *Notrack) unmarshal(fam byte, data []byte) error {
 	ad, err := netlink.NewAttributeDecoder(data)
 

expr/numgen.go

@@ -32,6 +32,18 @@ type Numgen struct {
 }
 
 func (e *Numgen) marshal(fam byte) ([]byte, error) {
+	data, err := e.marshalData(fam)
+	if err != nil {
+		return nil, err
+	}
+
+	return netlink.MarshalAttributes([]netlink.Attribute{
+		{Type: unix.NFTA_EXPR_NAME, Data: []byte("numgen\x00")},
+		{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: data},
+	})
+}
+
+func (e *Numgen) marshalData(fam byte) ([]byte, error) {
 	// Currently only two types are supported, failing if Type is not of two known types
 	switch e.Type {
 	case unix.NFT_NG_INCREMENTAL:
@@ -40,20 +52,12 @@ func (e *Numgen) marshal(fam byte) ([]byte, error) {
 		return nil, fmt.Errorf("unsupported numgen type %d", e.Type)
 	}
 
-	data, err := netlink.MarshalAttributes([]netlink.Attribute{
+	return netlink.MarshalAttributes([]netlink.Attribute{
 		{Type: unix.NFTA_NG_DREG, Data: binaryutil.BigEndian.PutUint32(e.Register)},
 		{Type: unix.NFTA_NG_MODULUS, Data: binaryutil.BigEndian.PutUint32(e.Modulus)},
 		{Type: unix.NFTA_NG_TYPE, Data: binaryutil.BigEndian.PutUint32(e.Type)},
 		{Type: unix.NFTA_NG_OFFSET, Data: binaryutil.BigEndian.PutUint32(e.Offset)},
 	})
-	if err != nil {
-		return nil, err
-	}
-
-	return netlink.MarshalAttributes([]netlink.Attribute{
-		{Type: unix.NFTA_EXPR_NAME, Data: []byte("numgen\x00")},
-		{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: data},
-	})
 }
 
 func (e *Numgen) unmarshal(fam byte, data []byte) error {

expr/objref.go

@@ -28,10 +28,7 @@ type Objref struct {
 }
 
 func (e *Objref) marshal(fam byte) ([]byte, error) {
-	data, err := netlink.MarshalAttributes([]netlink.Attribute{
+	data, err := e.marshalData(fam)
-		{Type: unix.NFTA_OBJREF_IMM_TYPE, Data: binaryutil.BigEndian.PutUint32(uint32(e.Type))},
-		{Type: unix.NFTA_OBJREF_IMM_NAME, Data: []byte(e.Name)}, // NOT \x00-terminated?!
-	})
 	if err != nil {
 		return nil, err
 	}
@@ -42,6 +39,13 @@ func (e *Objref) marshal(fam byte) ([]byte, error) {
 	})
 }
 
+func (e *Objref) marshalData(fam byte) ([]byte, error) {
+	return netlink.MarshalAttributes([]netlink.Attribute{
+		{Type: unix.NFTA_OBJREF_IMM_TYPE, Data: binaryutil.BigEndian.PutUint32(uint32(e.Type))},
+		{Type: unix.NFTA_OBJREF_IMM_NAME, Data: []byte(e.Name)}, // NOT \x00-terminated?!
+	})
+}
+
 func (e *Objref) unmarshal(fam byte, data []byte) error {
 	ad, err := netlink.NewAttributeDecoder(data)
 	if err != nil {

expr/payload.go

@@ -58,7 +58,18 @@ type Payload struct {
 }
 
 func (e *Payload) marshal(fam byte) ([]byte, error) {
+	data, err := e.marshalData(fam)
+	if err != nil {
+		return nil, err
+	}
 
+	return netlink.MarshalAttributes([]netlink.Attribute{
+		{Type: unix.NFTA_EXPR_NAME, Data: []byte("payload\x00")},
+		{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: data},
+	})
+}
+
+func (e *Payload) marshalData(fam byte) ([]byte, error) {
 	var attrs []netlink.Attribute
 
 	if e.OperationType == PayloadWrite {
@@ -89,15 +100,7 @@ func (e *Payload) marshal(fam byte) ([]byte, error) {
 		}
 	}
 
-	data, err := netlink.MarshalAttributes(attrs)
+	return netlink.MarshalAttributes(attrs)
-
-	if err != nil {
-		return nil, err
-	}
-	return netlink.MarshalAttributes([]netlink.Attribute{
-		{Type: unix.NFTA_EXPR_NAME, Data: []byte("payload\x00")},
-		{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: data},
-	})
 }
 
 func (e *Payload) unmarshal(fam byte, data []byte) error {

expr/queue.go

@@ -44,14 +44,7 @@ type Queue struct {
 }
 
 func (e *Queue) marshal(fam byte) ([]byte, error) {
-	if e.Total == 0 {
+	data, err := e.marshalData(fam)
-		e.Total = 1 // The total default value is 1
-	}
-	data, err := netlink.MarshalAttributes([]netlink.Attribute{
-		{Type: unix.NFTA_QUEUE_NUM, Data: binaryutil.BigEndian.PutUint16(e.Num)},
-		{Type: unix.NFTA_QUEUE_TOTAL, Data: binaryutil.BigEndian.PutUint16(e.Total)},
-		{Type: unix.NFTA_QUEUE_FLAGS, Data: binaryutil.BigEndian.PutUint16(uint16(e.Flag))},
-	})
 	if err != nil {
 		return nil, err
 	}
@@ -61,6 +54,17 @@ func (e *Queue) marshal(fam byte) ([]byte, error) {
 	})
 }
 
+func (e *Queue) marshalData(fam byte) ([]byte, error) {
+	if e.Total == 0 {
+		e.Total = 1 // The total default value is 1
+	}
+	return netlink.MarshalAttributes([]netlink.Attribute{
+		{Type: unix.NFTA_QUEUE_NUM, Data: binaryutil.BigEndian.PutUint16(e.Num)},
+		{Type: unix.NFTA_QUEUE_TOTAL, Data: binaryutil.BigEndian.PutUint16(e.Total)},
+		{Type: unix.NFTA_QUEUE_FLAGS, Data: binaryutil.BigEndian.PutUint16(uint16(e.Flag))},
+	})
+}
+
 func (e *Queue) unmarshal(fam byte, data []byte) error {
 	ad, err := netlink.NewAttributeDecoder(data)
 	if err != nil {

expr/quota.go

@@ -30,6 +30,18 @@ type Quota struct {
 }
 
 func (q *Quota) marshal(fam byte) ([]byte, error) {
+	data, err := q.marshalData(fam)
+	if err != nil {
+		return nil, err
+	}
+
+	return netlink.MarshalAttributes([]netlink.Attribute{
+		{Type: unix.NFTA_EXPR_NAME, Data: []byte("quota\x00")},
+		{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: data},
+	})
+}
+
+func (q *Quota) marshalData(fam byte) ([]byte, error) {
 	attrs := []netlink.Attribute{
 		{Type: unix.NFTA_QUOTA_BYTES, Data: binaryutil.BigEndian.PutUint64(q.Bytes)},
 		{Type: unix.NFTA_QUOTA_CONSUMED, Data: binaryutil.BigEndian.PutUint64(q.Consumed)},
@@ -44,15 +56,7 @@ func (q *Quota) marshal(fam byte) ([]byte, error) {
 		Data: binaryutil.BigEndian.PutUint32(flags),
 	})
 
-	data, err := netlink.MarshalAttributes(attrs)
+	return netlink.MarshalAttributes(attrs)
-	if err != nil {
-		return nil, err
-	}
-
-	return netlink.MarshalAttributes([]netlink.Attribute{
-		{Type: unix.NFTA_EXPR_NAME, Data: []byte("quota\x00")},
-		{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: data},
-	})
 }
 
 func (q *Quota) unmarshal(fam byte, data []byte) error {

expr/range.go

@@ -31,6 +31,18 @@ type Range struct {
 }
 
 func (e *Range) marshal(fam byte) ([]byte, error) {
+	data, err := e.marshalData(fam)
+	if err != nil {
+		return nil, err
+	}
+
+	return netlink.MarshalAttributes([]netlink.Attribute{
+		{Type: unix.NFTA_EXPR_NAME, Data: []byte("range\x00")},
+		{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: data},
+	})
+}
+
+func (e *Range) marshalData(fam byte) ([]byte, error) {
 	var attrs []netlink.Attribute
 	var err error
 	var rangeFromData, rangeToData []byte
@@ -57,11 +69,7 @@ func (e *Range) marshal(fam byte) ([]byte, error) {
 	}
 	data = append(data, rangeFromData...)
 	data = append(data, rangeToData...)
-
+	return data, nil
-	return netlink.MarshalAttributes([]netlink.Attribute{
-		{Type: unix.NFTA_EXPR_NAME, Data: []byte("range\x00")},
-		{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: data},
-	})
 }
 
 func (e *Range) unmarshal(fam byte, data []byte) error {

expr/redirect.go

@@ -29,6 +29,18 @@ type Redir struct {
 }
 
 func (e *Redir) marshal(fam byte) ([]byte, error) {
+	data, err := e.marshalData(fam)
+	if err != nil {
+		return nil, err
+	}
+
+	return netlink.MarshalAttributes([]netlink.Attribute{
+		{Type: unix.NFTA_EXPR_NAME, Data: []byte("redir\x00")},
+		{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: data},
+	})
+}
+
+func (e *Redir) marshalData(fam byte) ([]byte, error) {
 	var attrs []netlink.Attribute
 	if e.RegisterProtoMin > 0 {
 		attrs = append(attrs, netlink.Attribute{Type: unix.NFTA_REDIR_REG_PROTO_MIN, Data: binaryutil.BigEndian.PutUint32(e.RegisterProtoMin)})
@@ -40,15 +52,7 @@ func (e *Redir) marshal(fam byte) ([]byte, error) {
 		attrs = append(attrs, netlink.Attribute{Type: unix.NFTA_REDIR_FLAGS, Data: binaryutil.BigEndian.PutUint32(e.Flags)})
 	}
 
-	data, err := netlink.MarshalAttributes(attrs)
+	return netlink.MarshalAttributes(attrs)
-	if err != nil {
-		return nil, err
-	}
-
-	return netlink.MarshalAttributes([]netlink.Attribute{
-		{Type: unix.NFTA_EXPR_NAME, Data: []byte("redir\x00")},
-		{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: data},
-	})
 }
 
 func (e *Redir) unmarshal(fam byte, data []byte) error {

expr/reject.go

@@ -28,10 +28,7 @@ type Reject struct {
 }
 
 func (e *Reject) marshal(fam byte) ([]byte, error) {
-	data, err := netlink.MarshalAttributes([]netlink.Attribute{
+	data, err := e.marshalData(fam)
-		{Type: unix.NFTA_REJECT_TYPE, Data: binaryutil.BigEndian.PutUint32(e.Type)},
-		{Type: unix.NFTA_REJECT_ICMP_CODE, Data: []byte{e.Code}},
-	})
 	if err != nil {
 		return nil, err
 	}
@@ -41,6 +38,13 @@ func (e *Reject) marshal(fam byte) ([]byte, error) {
 	})
 }
 
+func (e *Reject) marshalData(fam byte) ([]byte, error) {
+	return netlink.MarshalAttributes([]netlink.Attribute{
+		{Type: unix.NFTA_REJECT_TYPE, Data: binaryutil.BigEndian.PutUint32(e.Type)},
+		{Type: unix.NFTA_REJECT_ICMP_CODE, Data: []byte{e.Code}},
+	})
+}
+
 func (e *Reject) unmarshal(fam byte, data []byte) error {
 	ad, err := netlink.NewAttributeDecoder(data)
 	if err != nil {

expr/rt.go

@@ -37,10 +37,7 @@ type Rt struct {
 }
 
 func (e *Rt) marshal(fam byte) ([]byte, error) {
-	data, err := netlink.MarshalAttributes([]netlink.Attribute{
+	data, err := e.marshalData(fam)
-		{Type: unix.NFTA_RT_KEY, Data: binaryutil.BigEndian.PutUint32(uint32(e.Key))},
-		{Type: unix.NFTA_RT_DREG, Data: binaryutil.BigEndian.PutUint32(e.Register)},
-	})
 	if err != nil {
 		return nil, err
 	}
@@ -50,6 +47,13 @@ func (e *Rt) marshal(fam byte) ([]byte, error) {
 	})
 }
 
+func (e *Rt) marshalData(fam byte) ([]byte, error) {
+	return netlink.MarshalAttributes([]netlink.Attribute{
+		{Type: unix.NFTA_RT_KEY, Data: binaryutil.BigEndian.PutUint32(uint32(e.Key))},
+		{Type: unix.NFTA_RT_DREG, Data: binaryutil.BigEndian.PutUint32(e.Register)},
+	})
+}
+
 func (e *Rt) unmarshal(fam byte, data []byte) error {
 	return fmt.Errorf("not yet implemented")
 }

expr/socket.go

@@ -49,23 +49,26 @@ const (
 )
 
 func (e *Socket) marshal(fam byte) ([]byte, error) {
+	exprData, err := e.marshalData(fam)
+	if err != nil {
+		return nil, err
+	}
+	return netlink.MarshalAttributes([]netlink.Attribute{
+		{Type: unix.NFTA_EXPR_NAME, Data: []byte("socket\x00")},
+		{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: exprData},
+	})
+}
+
+func (e *Socket) marshalData(fam byte) ([]byte, error) {
 	// NOTE: Socket.Level is only used when Socket.Key == SocketKeyCgroupv2. But `nft` always encoding it. Check link below:
 	// http://git.netfilter.org/nftables/tree/src/netlink_linearize.c?id=0583bac241ea18c9d7f61cb20ca04faa1e043b78#n319
-	exprData, err := netlink.MarshalAttributes(
+	return netlink.MarshalAttributes(
 		[]netlink.Attribute{
 			{Type: NFTA_SOCKET_DREG, Data: binaryutil.BigEndian.PutUint32(e.Register)},
 			{Type: NFTA_SOCKET_KEY, Data: binaryutil.BigEndian.PutUint32(uint32(e.Key))},
 			{Type: NFTA_SOCKET_LEVEL, Data: binaryutil.BigEndian.PutUint32(uint32(e.Level))},
 		},
 	)
-	if err != nil {
-		return nil, err
-	}
-
-	return netlink.MarshalAttributes([]netlink.Attribute{
-		{Type: unix.NFTA_EXPR_NAME, Data: []byte("socket\x00")},
-		{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: exprData},
-	})
 }
 
 func (e *Socket) unmarshal(fam byte, data []byte) error {

expr/target.go

@@ -21,6 +21,17 @@ type Target struct {
 }
 
 func (e *Target) marshal(fam byte) ([]byte, error) {
+	data, err := e.marshalData(fam)
+	if err != nil {
+		return nil, err
+	}
+	return netlink.MarshalAttributes([]netlink.Attribute{
+		{Type: unix.NFTA_EXPR_NAME, Data: []byte("target\x00")},
+		{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: data},
+	})
+}
+
+func (e *Target) marshalData(fam byte) ([]byte, error) {
 	// Per https://git.netfilter.org/libnftnl/tree/src/expr/target.c?id=09456c720e9c00eecc08e41ac6b7c291b3821ee5#n38
 	name := e.Name
 	// limit the extension name as (some) user-space tools do and leave room for
@@ -40,15 +51,7 @@ func (e *Target) marshal(fam byte) ([]byte, error) {
 		{Type: unix.NFTA_TARGET_INFO, Data: info},
 	}
 
-	data, err := netlink.MarshalAttributes(attrs)
+	return netlink.MarshalAttributes(attrs)
-	if err != nil {
-		return nil, err
-	}
-
-	return netlink.MarshalAttributes([]netlink.Attribute{
-		{Type: unix.NFTA_EXPR_NAME, Data: []byte("target\x00")},
-		{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: data},
-	})
 }
 
 func (e *Target) unmarshal(fam byte, data []byte) error {

expr/tproxy.go

@@ -40,6 +40,17 @@ type TProxy struct {
 }
 
 func (e *TProxy) marshal(fam byte) ([]byte, error) {
+	data, err := e.marshalData(fam)
+	if err != nil {
+		return nil, err
+	}
+	return netlink.MarshalAttributes([]netlink.Attribute{
+		{Type: unix.NFTA_EXPR_NAME, Data: []byte("tproxy\x00")},
+		{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: data},
+	})
+}
+
+func (e *TProxy) marshalData(fam byte) ([]byte, error) {
 	attrs := []netlink.Attribute{
 		{Type: NFTA_TPROXY_FAMILY, Data: binaryutil.BigEndian.PutUint32(uint32(e.Family))},
 		{Type: NFTA_TPROXY_REG_PORT, Data: binaryutil.BigEndian.PutUint32(e.RegPort)},
@@ -52,14 +63,7 @@ func (e *TProxy) marshal(fam byte) ([]byte, error) {
 		})
 	}
 
-	data, err := netlink.MarshalAttributes(attrs)
+	return netlink.MarshalAttributes(attrs)
-	if err != nil {
-		return nil, err
-	}
-	return netlink.MarshalAttributes([]netlink.Attribute{
-		{Type: unix.NFTA_EXPR_NAME, Data: []byte("tproxy\x00")},
-		{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: data},
-	})
 }
 
 func (e *TProxy) unmarshal(fam byte, data []byte) error {

expr/verdict.go

@@ -64,7 +64,17 @@ func (e *Verdict) marshal(fam byte) ([]byte, error) {
 	//     }
 	//   }
 	// }
+	data, err := e.marshalData(fam)
+	if err != nil {
+		return nil, err
+	}
+	return netlink.MarshalAttributes([]netlink.Attribute{
+		{Type: unix.NFTA_EXPR_NAME, Data: []byte("immediate\x00")},
+		{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: data},
+	})
+}
 
+func (e *Verdict) marshalData(fam byte) ([]byte, error) {
 	attrs := []netlink.Attribute{
 		{Type: unix.NFTA_VERDICT_CODE, Data: binaryutil.BigEndian.PutUint32(uint32(e.Kind))},
 	}
@@ -83,17 +93,10 @@ func (e *Verdict) marshal(fam byte) ([]byte, error) {
 		return nil, err
 	}
 
-	data, err := netlink.MarshalAttributes([]netlink.Attribute{
+	return netlink.MarshalAttributes([]netlink.Attribute{
 		{Type: unix.NFTA_IMMEDIATE_DREG, Data: binaryutil.BigEndian.PutUint32(unix.NFT_REG_VERDICT)},
 		{Type: unix.NLA_F_NESTED | unix.NFTA_IMMEDIATE_DATA, Data: immData},
 	})
-	if err != nil {
-		return nil, err
-	}
-	return netlink.MarshalAttributes([]netlink.Attribute{
-		{Type: unix.NFTA_EXPR_NAME, Data: []byte("immediate\x00")},
-		{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: data},
-	})
 }
 
 func (e *Verdict) unmarshal(fam byte, data []byte) error {

internal/parseexprfunc/parseexprfunc.go

@@ -5,6 +5,6 @@ import (
 )
 
 var (
-	ParseExprBytesFunc func(fam byte, ad *netlink.AttributeDecoder, b []byte) ([]interface{}, error)
+	ParseExprBytesFunc func(fam byte, ad *netlink.AttributeDecoder, args ...string) ([]interface{}, error)
-	ParseExprMsgFunc   func(fam byte, b []byte) ([]interface{}, error)
+	ParseExprMsgFunc   func(fam byte, b []byte, args ...string) ([]interface{}, error)
 )

monitor.go

@@ -259,7 +259,7 @@ func (monitor *Monitor) monitor() {
 				}
 				monitor.eventCh <- event
 			case unix.NFT_MSG_NEWOBJ, unix.NFT_MSG_DELOBJ:
-				obj, err := objFromMsg(msg)
+				obj, err := objFromMsg(msg, true)
 				event := &MonitorEvent{
 					Type:  MonitorEventType(msgType),
 					Data:  obj,

nftables_test.go

@@ -1783,7 +1783,7 @@ func TestListChainByName(t *testing.T) {
 }
 
 func TestListChainByNameUsingLasting(t *testing.T) {
-	conn, newNS := nftest.OpenSystemConn(t, *enableSysTests)
+	_, newNS := nftest.OpenSystemConn(t, *enableSysTests)
 	conn, err := nftables.New(nftables.WithNetNSFd(int(newNS)), nftables.AsLasting())
 	if err != nil {
 		t.Fatalf("nftables.New() failed: %v", err)
@@ -1882,8 +1882,7 @@ func TestListTableByName(t *testing.T) {
 	}
 
 	// not specifying correct family should return err since no table in ipv4
-	tr, err = conn.ListTable(table2.Name)
+	if _, err = conn.ListTable(table2.Name); err == nil {
-	if err == nil {
 		t.Fatalf("conn.ListTable() should have failed")
 	}
 
@@ -2106,17 +2105,18 @@ func TestGetObjReset(t *testing.T) {
 	}
 
 	filter := &nftables.Table{Name: "filter", Family: nftables.TableFamilyIPv4}
-	obj, err := c.ResetObject(&nftables.CounterObj{
+	obj, err := c.ResetObject(&nftables.ObjAttr{
 		Table: filter,
 		Name:  "fwded",
+		Type:  nftables.ObjTypeCounter,
 	})
 	if err != nil {
 		t.Fatal(err)
 	}
 
-	co, ok := obj.(*nftables.CounterObj)
+	co, ok := obj.(*nftables.ObjAttr)
 	if !ok {
-		t.Fatalf("unexpected type: got %T, want *nftables.CounterObj", obj)
+		t.Fatalf("unexpected type: got %T, want *nftables.ObjAttr", obj)
 	}
 	if got, want := co.Table.Name, filter.Name; got != want {
 		t.Errorf("unexpected table name: got %q, want %q", got, want)
@@ -2124,10 +2124,14 @@ func TestGetObjReset(t *testing.T) {
 	if got, want := co.Table.Family, filter.Family; got != want {
 		t.Errorf("unexpected table family: got %d, want %d", got, want)
 	}
-	if got, want := co.Packets, uint64(9); got != want {
+	o, ok := co.Obj.(*expr.Counter)
+	if !ok {
+		t.Fatalf("unexpected type: got %T, want *expr.Counter", o)
+	}
+	if got, want := o.Packets, uint64(9); got != want {
 		t.Errorf("unexpected number of packets: got %d, want %d", got, want)
 	}
-	if got, want := co.Bytes, uint64(1121); got != want {
+	if got, want := o.Bytes, uint64(1121); got != want {
 		t.Errorf("unexpected number of bytes: got %d, want %d", got, want)
 	}
 }
@@ -2164,6 +2168,366 @@ func TestObjAPI(t *testing.T) {
 		Priority: nftables.ChainPriorityFilter,
 	})
 
+	counter1 := c.AddObj(&nftables.ObjAttr{
+		Table: table,
+		Name:  "fwded1",
+		Type:  nftables.ObjTypeCounter,
+		Obj: &expr.Counter{
+			Bytes:   1,
+			Packets: 1,
+		},
+	})
+
+	counter2 := c.AddObj(&nftables.ObjAttr{
+		Table: table,
+		Name:  "fwded2",
+		Type:  nftables.ObjTypeCounter,
+		Obj: &expr.Counter{
+			Bytes:   1,
+			Packets: 1,
+		},
+	})
+
+	c.AddObj(&nftables.ObjAttr{
+		Table: tableOther,
+		Name:  "fwdedOther",
+		Type:  nftables.ObjTypeCounter,
+		Obj: &expr.Counter{
+			Bytes:   0,
+			Packets: 0,
+		},
+	})
+
+	c.AddRule(&nftables.Rule{
+		Table: table,
+		Chain: chain,
+		Exprs: []expr.Any{
+			&expr.Objref{
+				Type: 1,
+				Name: "fwded1",
+			},
+		},
+	})
+
+	if err := c.Flush(); err != nil {
+		t.Fatalf(err.Error())
+	}
+
+	objs, err := c.GetObjects(table)
+	if err != nil {
+		t.Errorf("c.GetObjects(table) failed: %v failed", err)
+	}
+
+	if got := len(objs); got != 2 {
+		t.Fatalf("unexpected number of objects: got %d, want %d", got, 2)
+	}
+
+	objsOther, err := c.GetObjects(tableOther)
+	if err != nil {
+		t.Errorf("c.GetObjects(tableOther) failed: %v failed", err)
+	}
+
+	if got := len(objsOther); got != 1 {
+		t.Fatalf("unexpected number of objects: got %d, want %d", got, 1)
+	}
+
+	obj1, err := c.GetObject(counter1)
+	if err != nil {
+		t.Errorf("c.GetObject(counter1) failed: %v failed", err)
+	}
+
+	rcounter1, ok := obj1.(*nftables.ObjAttr)
+	if !ok {
+		t.Fatalf("unexpected type: got %T, want *nftables.ObjAttr", obj1)
+	}
+
+	if rcounter1.Name != "fwded1" {
+		t.Fatalf("unexpected counter name: got %s, want %s", rcounter1.Name, "fwded1")
+	}
+
+	obj2, err := c.GetObject(counter2)
+	if err != nil {
+		t.Errorf("c.GetObject(counter2) failed: %v failed", err)
+	}
+
+	rcounter2, ok := obj2.(*nftables.ObjAttr)
+	if !ok {
+		t.Fatalf("unexpected type: got %T, want *nftables.CounterObj", obj2)
+	}
+
+	if rcounter2.Name != "fwded2" {
+		t.Fatalf("unexpected counter name: got %s, want %s", rcounter2.Name, "fwded2")
+	}
+
+	_, err = c.ResetObject(counter1)
+
+	if err != nil {
+		t.Errorf("c.ResetObjects(table) failed: %v failed", err)
+	}
+
+	obj1, err = c.GetObject(counter1)
+
+	if err != nil {
+		t.Errorf("c.GetObject(counter1) failed: %v failed", err)
+	}
+
+	if counter1 := obj1.(*nftables.ObjAttr).Obj.(*expr.Counter); counter1.Packets > 0 {
+		t.Errorf("unexpected packets number: got %d, want %d", counter1.Packets, 0)
+	}
+
+	obj2, err = c.GetObject(counter2)
+
+	if err != nil {
+		t.Errorf("c.GetObject(counter2) failed: %v failed", err)
+	}
+
+	if counter2 := obj2.(*nftables.ObjAttr).Obj.(*expr.Counter); counter2.Packets != 1 {
+		t.Errorf("unexpected packets number: got %d, want %d", counter2.Packets, 1)
+	}
+
+	legacy, err := c.GetObj(counter1)
+	if err != nil {
+		t.Errorf("c.GetObj(counter1) failed: %v failed", err)
+	}
+
+	if len(legacy) != 2 {
+		t.Errorf("unexpected number of objects: got %d, want %d", len(legacy), 2)
+	}
+
+	legacyReset, err := c.GetObjReset(counter1)
+	if err != nil {
+		t.Errorf("c.GetObjReset(counter1) failed: %v failed", err)
+	}
+
+	if len(legacyReset) != 2 {
+		t.Errorf("unexpected number of objects: got %d, want %d", len(legacyReset), 2)
+	}
+}
+
+func TestDeleteLegacyQuotaObj(t *testing.T) {
+	conn, newNS := nftest.OpenSystemConn(t, *enableSysTests)
+	defer nftest.CleanupSystemConn(t, newNS)
+	conn.FlushRuleset()
+	defer conn.FlushRuleset()
+
+	table := &nftables.Table{
+		Name:   "quota_demo",
+		Family: nftables.TableFamilyIPv4,
+	}
+	tr := conn.AddTable(table)
+
+	c := &nftables.Chain{
+		Name:  "filter",
+		Table: table,
+	}
+	conn.AddChain(c)
+
+	o := &nftables.QuotaObj{
+		Table:    tr,
+		Name:     "q_test",
+		Bytes:    0x06400000,
+		Consumed: 0,
+		Over:     true,
+	}
+	conn.AddObj(o)
+
+	if err := conn.Flush(); err != nil {
+		t.Fatalf("conn.Flush() failed: %v", err)
+	}
+
+	obj, err := conn.GetObj(&nftables.QuotaObj{
+		Table: table,
+		Name:  "q_test",
+	})
+	if err != nil {
+		t.Fatalf("conn.GetObj() failed: %v", err)
+	}
+
+	if got, want := len(obj), 1; got != want {
+		t.Fatalf("unexpected number of objects: got %d, want %d", got, want)
+	}
+
+	if got, want := obj[0], o; !reflect.DeepEqual(got, want) {
+		t.Errorf("got = %+v, want = %+v", got, want)
+	}
+
+	conn.DeleteObject(&nftables.QuotaObj{
+		Table: tr,
+		Name:  "q_test",
+	})
+
+	if err := conn.Flush(); err != nil {
+		t.Fatalf("conn.Flush() failed: %v", err)
+	}
+
+	obj, err = conn.GetObj(&nftables.QuotaObj{
+		Table: table,
+		Name:  "q_test",
+	})
+	if err != nil {
+		t.Fatalf("conn.GetObj() failed: %v", err)
+	}
+	if got, want := len(obj), 0; got != want {
+		t.Fatalf("unexpected object list length: got %d, want %d", got, want)
+	}
+}
+
+func TestAddLegacyQuotaObj(t *testing.T) {
+	conn, newNS := nftest.OpenSystemConn(t, *enableSysTests)
+	defer nftest.CleanupSystemConn(t, newNS)
+	conn.FlushRuleset()
+	defer conn.FlushRuleset()
+
+	table := &nftables.Table{
+		Name:   "quota_demo",
+		Family: nftables.TableFamilyIPv4,
+	}
+	tr := conn.AddTable(table)
+
+	c := &nftables.Chain{
+		Name:  "filter",
+		Table: table,
+	}
+	conn.AddChain(c)
+
+	o := &nftables.QuotaObj{
+		Table:    tr,
+		Name:     "q_test",
+		Bytes:    0x06400000,
+		Consumed: 0,
+		Over:     true,
+	}
+	conn.AddObj(o)
+
+	if err := conn.Flush(); err != nil {
+		t.Errorf("conn.Flush() failed: %v", err)
+	}
+
+	obj, err := conn.GetObj(&nftables.QuotaObj{
+		Table: table,
+		Name:  "q_test",
+	})
+	if err != nil {
+		t.Fatalf("conn.GetObj() failed: %v", err)
+	}
+
+	if got, want := len(obj), 1; got != want {
+		t.Fatalf("unexpected object list length: got %d, want %d", got, want)
+	}
+
+	o1, ok := obj[0].(*nftables.QuotaObj)
+	if !ok {
+		t.Fatalf("unexpected type: got %T, want *QuotaObj", obj[0])
+	}
+	if got, want := o1.Name, o.Name; got != want {
+		t.Fatalf("quota name mismatch: got %s, want %s", got, want)
+	}
+	if got, want := o1.Bytes, o.Bytes; got != want {
+		t.Fatalf("quota bytes mismatch: got %d, want %d", got, want)
+	}
+	if got, want := o1.Consumed, o.Consumed; got != want {
+		t.Fatalf("quota consumed mismatch: got %d, want %d", got, want)
+	}
+	if got, want := o1.Over, o.Over; got != want {
+		t.Fatalf("quota over mismatch: got %v, want %v", got, want)
+	}
+}
+
+func TestAddLegacyQuotaObjRef(t *testing.T) {
+	conn, newNS := nftest.OpenSystemConn(t, *enableSysTests)
+	defer nftest.CleanupSystemConn(t, newNS)
+	conn.FlushRuleset()
+	defer conn.FlushRuleset()
+
+	table := &nftables.Table{
+		Name:   "quota_demo",
+		Family: nftables.TableFamilyIPv4,
+	}
+	tr := conn.AddTable(table)
+
+	c := &nftables.Chain{
+		Name:  "filter",
+		Table: table,
+	}
+	conn.AddChain(c)
+
+	o := &nftables.QuotaObj{
+		Table:    tr,
+		Name:     "q_test",
+		Bytes:    0x06400000,
+		Consumed: 0,
+		Over:     true,
+	}
+	conn.AddObj(o)
+
+	r := &nftables.Rule{
+		Table: table,
+		Chain: c,
+		Exprs: []expr.Any{
+			&expr.Objref{
+				Type: 2,
+				Name: "q_test",
+			},
+		},
+	}
+	conn.AddRule(r)
+	if err := conn.Flush(); err != nil {
+		t.Fatalf("failed to flush: %v", err)
+	}
+
+	rules, err := conn.GetRules(table, c)
+	if err != nil {
+		t.Fatalf("failed to get rules: %v", err)
+	}
+
+	if got, want := len(rules), 1; got != want {
+		t.Fatalf("unexpected number of rules: got %d, want %d", got, want)
+	}
+	if got, want := len(rules[0].Exprs), 1; got != want {
+		t.Fatalf("unexpected number of exprs: got %d, want %d", got, want)
+	}
+
+	objref, ok := rules[0].Exprs[0].(*expr.Objref)
+	if !ok {
+		t.Fatalf("Exprs[0] is type %T, want *expr.Objref", rules[0].Exprs[0])
+	}
+	if want := r.Exprs[0]; !reflect.DeepEqual(objref, want) {
+		t.Errorf("objref expr = %+v, wanted %+v", objref, want)
+	}
+}
+
+func TestObjAPICounterLegacyType(t *testing.T) {
+	if os.Getenv("TRAVIS") == "true" {
+		t.SkipNow()
+	}
+
+	// Create a new network namespace to test these operations,
+	// and tear down the namespace at test completion.
+	c, newNS := nftest.OpenSystemConn(t, *enableSysTests)
+	defer nftest.CleanupSystemConn(t, newNS)
+
+	// Clear all rules at the beginning + end of the test.
+	c.FlushRuleset()
+	defer c.FlushRuleset()
+
+	table := c.AddTable(&nftables.Table{
+		Family: nftables.TableFamilyIPv4,
+		Name:   "filter",
+	})
+
+	tableOther := c.AddTable(&nftables.Table{
+		Family: nftables.TableFamilyIPv4,
+		Name:   "foo",
+	})
+
+	chain := c.AddChain(&nftables.Chain{
+		Name:     "chain",
+		Table:    table,
+		Type:     nftables.ChainTypeFilter,
+		Hooknum:  nftables.ChainHookPostrouting,
+		Priority: nftables.ChainPriorityFilter,
+	})
+
 	counter1 := c.AddObj(&nftables.CounterObj{
 		Table:   table,
 		Name:    "fwded1",
@@ -2767,7 +3131,7 @@ func TestCreateUseAnonymousSet(t *testing.T) {
 }
 
 func TestCappedErrMsgOnSets(t *testing.T) {
-	c, newNS := nftest.OpenSystemConn(t, *enableSysTests)
+	_, newNS := nftest.OpenSystemConn(t, *enableSysTests)
 	c, err := nftables.New(nftables.WithNetNSFd(int(newNS)), nftables.AsLasting())
 	if err != nil {
 		t.Fatalf("nftables.New() failed: %v", err)
@@ -6285,6 +6649,84 @@ func TestGetRulesObjref(t *testing.T) {
 	}
 }
 
+func TestAddLimitObj(t *testing.T) {
+	conn, newNS := nftest.OpenSystemConn(t, *enableSysTests)
+	defer nftest.CleanupSystemConn(t, newNS)
+	conn.FlushRuleset()
+	defer conn.FlushRuleset()
+
+	table := &nftables.Table{
+		Name:   "limit_demo",
+		Family: nftables.TableFamilyIPv4,
+	}
+	tr := conn.AddTable(table)
+
+	c := &nftables.Chain{
+		Name:  "filter",
+		Table: table,
+	}
+	conn.AddChain(c)
+
+	l := &expr.Limit{
+		Type:  expr.LimitTypePkts,
+		Rate:  400,
+		Unit:  expr.LimitTimeMinute,
+		Burst: 5,
+		Over:  false,
+	}
+	o := &nftables.ObjAttr{
+		Table: tr,
+		Name:  "limit_test",
+		Type:  nftables.ObjTypeLimit,
+		Obj:   l,
+	}
+	conn.AddObj(o)
+
+	if err := conn.Flush(); err != nil {
+		t.Errorf("conn.Flush() failed: %v", err)
+	}
+
+	obj, err := conn.GetObj(&nftables.ObjAttr{
+		Table: table,
+		Name:  "limit_test",
+		Type:  nftables.ObjTypeLimit,
+	})
+	if err != nil {
+		t.Fatalf("conn.GetObj() failed: %v", err)
+	}
+
+	if got, want := len(obj), 1; got != want {
+		t.Fatalf("unexpected object list length: got %d, want %d", got, want)
+	}
+
+	o1, ok := obj[0].(*nftables.ObjAttr)
+	if !ok {
+		t.Fatalf("unexpected type: got %T, want *ObjAttr", obj[0])
+	}
+	if got, want := o1.Name, o.Name; got != want {
+		t.Fatalf("limit name mismatch: got %s, want %s", got, want)
+	}
+	q, ok := o1.Obj.(*expr.Limit)
+	if !ok {
+		t.Fatalf("unexpected type: got %T, want *expr.Quota", o1.Obj)
+	}
+	if got, want := q.Burst, l.Burst; got != want {
+		t.Fatalf("limit burst mismatch: got %d, want %d", got, want)
+	}
+	if got, want := q.Unit, l.Unit; got != want {
+		t.Fatalf("limit unit mismatch: got %d, want %d", got, want)
+	}
+	if got, want := q.Rate, l.Rate; got != want {
+		t.Fatalf("limit rate mismatch: got %v, want %v", got, want)
+	}
+	if got, want := q.Over, l.Over; got != want {
+		t.Fatalf("limit over mismatch: got %v, want %v", got, want)
+	}
+	if got, want := q.Type, l.Type; got != want {
+		t.Fatalf("limit type mismatch: got %v, want %v", got, want)
+	}
+}
+
 func TestAddQuotaObj(t *testing.T) {
 	conn, newNS := nftest.OpenSystemConn(t, *enableSysTests)
 	defer nftest.CleanupSystemConn(t, newNS)
@@ -6303,22 +6745,26 @@ func TestAddQuotaObj(t *testing.T) {
 	}
 	conn.AddChain(c)
 
-	o := &nftables.QuotaObj{
+	o := &nftables.ObjAttr{
-		Table:    tr,
+		Table: tr,
-		Name:     "q_test",
+		Name:  "q_test",
-		Bytes:    0x06400000,
+		Type:  nftables.ObjTypeQuota,
-		Consumed: 0,
+		Obj: &expr.Quota{
-		Over:     true,
+			Bytes:    0x06400000,
+			Consumed: 0,
+			Over:     true,
+		},
 	}
 	conn.AddObj(o)
 
 	if err := conn.Flush(); err != nil {
-		t.Errorf("conn.Flush() failed: %v", err)
+		t.Fatalf("conn.Flush() failed: %v", err)
 	}
 
-	obj, err := conn.GetObj(&nftables.QuotaObj{
+	obj, err := conn.GetObj(&nftables.ObjAttr{
 		Table: table,
 		Name:  "q_test",
+		Type:  nftables.ObjTypeQuota,
 	})
 	if err != nil {
 		t.Fatalf("conn.GetObj() failed: %v", err)
@@ -6328,20 +6774,25 @@ func TestAddQuotaObj(t *testing.T) {
 		t.Fatalf("unexpected object list length: got %d, want %d", got, want)
 	}
 
-	o1, ok := obj[0].(*nftables.QuotaObj)
+	o1, ok := obj[0].(*nftables.ObjAttr)
 	if !ok {
-		t.Fatalf("unexpected type: got %T, want *QuotaObj", obj[0])
+		t.Fatalf("unexpected type: got %T, want *ObjAttr", obj[0])
 	}
 	if got, want := o1.Name, o.Name; got != want {
 		t.Fatalf("quota name mismatch: got %s, want %s", got, want)
 	}
-	if got, want := o1.Bytes, o.Bytes; got != want {
+	q, ok := o1.Obj.(*expr.Quota)
+	if !ok {
+		t.Fatalf("unexpected type: got %T, want *expr.Quota", o1.Obj)
+	}
+	o2, _ := o.Obj.(*expr.Quota)
+	if got, want := q.Bytes, o2.Bytes; got != want {
 		t.Fatalf("quota bytes mismatch: got %d, want %d", got, want)
 	}
-	if got, want := o1.Consumed, o.Consumed; got != want {
+	if got, want := q.Consumed, o2.Consumed; got != want {
 		t.Fatalf("quota consumed mismatch: got %d, want %d", got, want)
 	}
-	if got, want := o1.Over, o.Over; got != want {
+	if got, want := q.Over, o2.Over; got != want {
 		t.Fatalf("quota over mismatch: got %v, want %v", got, want)
 	}
 }
@@ -6409,7 +6860,7 @@ func TestAddQuotaObjRef(t *testing.T) {
 	}
 }
 
-func TestDeleteQuotaObj(t *testing.T) {
+func TestDeleteQuotaObjMixedTypes(t *testing.T) {
 	conn, newNS := nftest.OpenSystemConn(t, *enableSysTests)
 	defer nftest.CleanupSystemConn(t, newNS)
 	conn.FlushRuleset()
@@ -6427,12 +6878,15 @@ func TestDeleteQuotaObj(t *testing.T) {
 	}
 	conn.AddChain(c)
 
-	o := &nftables.QuotaObj{
+	o := &nftables.ObjAttr{
-		Table:    tr,
+		Table: tr,
-		Name:     "q_test",
+		Name:  "q_test",
-		Bytes:    0x06400000,
+		Type:  nftables.ObjTypeQuota,
-		Consumed: 0,
+		Obj: &expr.Quota{
-		Over:     true,
+			Bytes:    0x06400000,
+			Consumed: 0,
+			Over:     true,
+		},
 	}
 	conn.AddObj(o)
 
@@ -6440,9 +6894,10 @@ func TestDeleteQuotaObj(t *testing.T) {
 		t.Fatalf("conn.Flush() failed: %v", err)
 	}
 
-	obj, err := conn.GetObj(&nftables.QuotaObj{
+	obj, err := conn.GetObj(&nftables.ObjAttr{
-		Table: table,
+		Table: tr,
 		Name:  "q_test",
+		Type:  nftables.ObjTypeQuota,
 	})
 	if err != nil {
 		t.Fatalf("conn.GetObj() failed: %v", err)
@@ -6452,7 +6907,18 @@ func TestDeleteQuotaObj(t *testing.T) {
 		t.Fatalf("unexpected number of objects: got %d, want %d", got, want)
 	}
 
-	if got, want := obj[0], o; !reflect.DeepEqual(got, want) {
+	o2, _ := o.Obj.(*expr.Quota)
+	want := &nftables.ObjAttr{
+		Table: tr,
+		Name:  "q_test",
+		Type:  nftables.ObjTypeQuota,
+		Obj: &expr.Quota{
+			Bytes:    o2.Bytes,
+			Consumed: o2.Consumed,
+			Over:     o2.Over,
+		},
+	}
+	if got, want := obj[0], want; !reflect.DeepEqual(got, want) {
 		t.Errorf("got = %+v, want = %+v", got, want)
 	}
 

obj.go

@@ -18,6 +18,9 @@ import (
 	"encoding/binary"
 	"fmt"
 
+	"github.com/google/nftables/binaryutil"
+	"github.com/google/nftables/expr"
+	"github.com/google/nftables/internal/parseexprfunc"
 	"github.com/mdlayher/netlink"
 	"golang.org/x/sys/unix"
 )
@@ -27,13 +30,70 @@ var (
 	delObjHeaderType = netlink.HeaderType((unix.NFNL_SUBSYS_NFTABLES << 8) | unix.NFT_MSG_DELOBJ)
 )
 
+type ObjType uint32
+
+// https://git.netfilter.org/libnftnl/tree/include/linux/netfilter/nf_tables.h?id=be0bae0ad31b0adb506f96de083f52a2bd0d4fbf#n1612
+const (
+	ObjTypeCounter   ObjType = unix.NFT_OBJECT_COUNTER
+	ObjTypeQuota     ObjType = unix.NFT_OBJECT_QUOTA
+	ObjTypeCtHelper  ObjType = unix.NFT_OBJECT_CT_HELPER
+	ObjTypeLimit     ObjType = unix.NFT_OBJECT_LIMIT
+	ObjTypeConnLimit ObjType = unix.NFT_OBJECT_CONNLIMIT
+	ObjTypeTunnel    ObjType = unix.NFT_OBJECT_TUNNEL
+	ObjTypeCtTimeout ObjType = unix.NFT_OBJECT_CT_TIMEOUT
+	ObjTypeSecMark   ObjType = unix.NFT_OBJECT_SECMARK
+	ObjTypeCtExpect  ObjType = unix.NFT_OBJECT_CT_EXPECT
+	ObjTypeSynProxy  ObjType = unix.NFT_OBJECT_SYNPROXY
+)
+
+var objByObjTypeMagic = map[ObjType]string{
+	ObjTypeCounter:   "counter",
+	ObjTypeQuota:     "quota",
+	ObjTypeLimit:     "limit",
+	ObjTypeConnLimit: "connlimit",
+	ObjTypeCtHelper:  "cthelper",  // not implemented in expr
+	ObjTypeTunnel:    "tunnel",    // not implemented in expr
+	ObjTypeCtTimeout: "cttimeout", // not implemented in expr
+	ObjTypeSecMark:   "secmark",   // not implemented in expr
+	ObjTypeCtExpect:  "ctexpect",  // not implemented in expr
+	ObjTypeSynProxy:  "synproxy",  // not implemented in expr
+}
+
 // Obj represents a netfilter stateful object. See also
 // https://wiki.nftables.org/wiki-nftables/index.php/Stateful_objects
 type Obj interface {
 	table() *Table
 	family() TableFamily
-	unmarshal(*netlink.AttributeDecoder) error
+	data() expr.Any
-	marshal(data bool) ([]byte, error)
+	name() string
+	objType() ObjType
+}
+
+type ObjAttr struct {
+	Table *Table
+	Name  string
+	Type  ObjType
+	Obj   expr.Any
+}
+
+func (o *ObjAttr) table() *Table {
+	return o.Table
+}
+
+func (o *ObjAttr) family() TableFamily {
+	return o.Table.Family
+}
+
+func (o *ObjAttr) data() expr.Any {
+	return o.Obj
+}
+
+func (o *ObjAttr) name() string {
+	return o.Name
+}
+
+func (o *ObjAttr) objType() ObjType {
+	return o.Type
 }
 
 // AddObject adds the specified Obj. Alias of AddObj.
@@ -46,18 +106,27 @@ func (cc *Conn) AddObject(o Obj) Obj {
 func (cc *Conn) AddObj(o Obj) Obj {
 	cc.mu.Lock()
 	defer cc.mu.Unlock()
-	data, err := o.marshal(true)
+	data, err := expr.MarshalExprData(byte(o.family()), o.data())
 	if err != nil {
 		cc.setErr(err)
 		return nil
 	}
 
+	attrs := []netlink.Attribute{
+		{Type: unix.NFTA_OBJ_TABLE, Data: []byte(o.table().Name + "\x00")},
+		{Type: unix.NFTA_OBJ_NAME, Data: []byte(o.name() + "\x00")},
+		{Type: unix.NFTA_OBJ_TYPE, Data: binaryutil.BigEndian.PutUint32(uint32(o.objType()))},
+	}
+	if len(data) > 0 {
+		attrs = append(attrs, netlink.Attribute{Type: unix.NLA_F_NESTED | unix.NFTA_OBJ_DATA, Data: data})
+	}
+
 	cc.messages = append(cc.messages, netlink.Message{
 		Header: netlink.Header{
 			Type:  netlink.HeaderType((unix.NFNL_SUBSYS_NFTABLES << 8) | unix.NFT_MSG_NEWOBJ),
 			Flags: netlink.Request | netlink.Acknowledge | netlink.Create,
 		},
-		Data: append(extraHeader(uint8(o.family()), 0), data...),
+		Data: append(extraHeader(uint8(o.family()), 0), cc.marshalAttr(attrs)...),
 	})
 	return o
 }
@@ -66,12 +135,12 @@ func (cc *Conn) AddObj(o Obj) Obj {
 func (cc *Conn) DeleteObject(o Obj) {
 	cc.mu.Lock()
 	defer cc.mu.Unlock()
-	data, err := o.marshal(false)
+	attrs := []netlink.Attribute{
-	if err != nil {
+		{Type: unix.NFTA_OBJ_TABLE, Data: []byte(o.table().Name + "\x00")},
-		cc.setErr(err)
+		{Type: unix.NFTA_OBJ_NAME, Data: []byte(o.name() + "\x00")},
-		return
+		{Type: unix.NFTA_OBJ_TYPE, Data: binaryutil.BigEndian.PutUint32(uint32(o.objType()))},
 	}
-
+	data := cc.marshalAttr(attrs)
 	data = append(data, cc.marshalAttr([]netlink.Attribute{{Type: unix.NLA_F_NESTED | unix.NFTA_OBJ_DATA}})...)
 
 	cc.messages = append(cc.messages, netlink.Message{
@@ -86,13 +155,13 @@ func (cc *Conn) DeleteObject(o Obj) {
 // GetObj is a legacy method that return all Obj that belongs
 // to the same table as the given one
 func (cc *Conn) GetObj(o Obj) ([]Obj, error) {
-	return cc.getObj(nil, o.table(), unix.NFT_MSG_GETOBJ)
+	return cc.getObjWithLegacyType(nil, o.table(), unix.NFT_MSG_GETOBJ, cc.useLegacyObjType(o))
 }
 
 // GetObjReset is a legacy method that reset all Obj that belongs
 // the same table as the given one
 func (cc *Conn) GetObjReset(o Obj) ([]Obj, error) {
-	return cc.getObj(nil, o.table(), unix.NFT_MSG_GETOBJ_RESET)
+	return cc.getObjWithLegacyType(nil, o.table(), unix.NFT_MSG_GETOBJ_RESET, cc.useLegacyObjType(o))
 }
 
 // GetObject gets the specified Object
@@ -127,7 +196,7 @@ func (cc *Conn) ResetObjects(t *Table) ([]Obj, error) {
 	return cc.getObj(nil, t, unix.NFT_MSG_GETOBJ_RESET)
 }
 
-func objFromMsg(msg netlink.Message) (Obj, error) {
+func objFromMsg(msg netlink.Message, returnLegacyType bool) (Obj, error) {
 	if got, want1, want2 := msg.Header.Type, newObjHeaderType, delObjHeaderType; got != want1 && got != want2 {
 		return nil, fmt.Errorf("unexpected header type: got %v, want %v or %v", got, want1, want2)
 	}
@@ -150,6 +219,29 @@ func objFromMsg(msg netlink.Message) (Obj, error) {
 		case unix.NFTA_OBJ_TYPE:
 			objectType = ad.Uint32()
 		case unix.NFTA_OBJ_DATA:
+			if !returnLegacyType {
+				o := ObjAttr{
+					Table: table,
+					Name:  name,
+					Type:  ObjType(objectType),
+				}
+
+				objs, err := parseexprfunc.ParseExprBytesFunc(byte(o.family()), ad, objByObjTypeMagic[o.Type])
+				if err != nil {
+					return nil, err
+				}
+				exprs := make([]expr.Any, len(objs))
+				for i := range exprs {
+					exprs[i] = objs[i].(expr.Any)
+				}
+				if len(exprs) == 0 {
+					return nil, fmt.Errorf("objFromMsg: exprs is empty for obj %v", o)
+				}
+
+				o.Obj = exprs[0]
+				return &o, ad.Err()
+			}
+
 			switch objectType {
 			case unix.NFT_OBJECT_COUNTER:
 				o := CounterObj{
@@ -166,7 +258,7 @@ func objFromMsg(msg netlink.Message) (Obj, error) {
 					return o.unmarshal(ad)
 				})
 				return &o, ad.Err()
-			case NFT_OBJECT_QUOTA:
+			case unix.NFT_OBJECT_QUOTA:
 				o := QuotaObj{
 					Table: table,
 					Name:  name,
@@ -191,6 +283,10 @@ func objFromMsg(msg netlink.Message) (Obj, error) {
 }
 
 func (cc *Conn) getObj(o Obj, t *Table, msgType uint16) ([]Obj, error) {
+	return cc.getObjWithLegacyType(o, t, msgType, cc.useLegacyObjType(o))
+}
+
+func (cc *Conn) getObjWithLegacyType(o Obj, t *Table, msgType uint16, returnLegacyObjType bool) ([]Obj, error) {
 	conn, closer, err := cc.netlinkConn()
 	if err != nil {
 		return nil, err
@@ -201,7 +297,12 @@ func (cc *Conn) getObj(o Obj, t *Table, msgType uint16) ([]Obj, error) {
 	var flags netlink.HeaderFlags
 
 	if o != nil {
-		data, err = o.marshal(false)
+		attrs := []netlink.Attribute{
+			{Type: unix.NFTA_OBJ_TABLE, Data: []byte(o.table().Name + "\x00")},
+			{Type: unix.NFTA_OBJ_NAME, Data: []byte(o.name() + "\x00")},
+			{Type: unix.NFTA_OBJ_TYPE, Data: binaryutil.BigEndian.PutUint32(uint32(o.objType()))},
+		}
+		data = cc.marshalAttr(attrs)
 	} else {
 		flags = netlink.Dump
 		data, err = netlink.MarshalAttributes([]netlink.Attribute{
@@ -230,7 +331,7 @@ func (cc *Conn) getObj(o Obj, t *Table, msgType uint16) ([]Obj, error) {
 	}
 	var objs []Obj
 	for _, msg := range reply {
-		o, err := objFromMsg(msg)
+		o, err := objFromMsg(msg, returnLegacyObjType)
 		if err != nil {
 			return nil, err
 		}
@@ -239,3 +340,14 @@ func (cc *Conn) getObj(o Obj, t *Table, msgType uint16) ([]Obj, error) {
 
 	return objs, nil
 }
+
+func (cc *Conn) useLegacyObjType(o Obj) bool {
+	useLegacyType := true
+	if o != nil {
+		switch o.(type) {
+		case *ObjAttr:
+			useLegacyType = false
+		}
+	}
+	return useLegacyType
+}

quota.go

@@ -16,15 +16,11 @@ package nftables
 
 import (
 	"github.com/google/nftables/binaryutil"
+	"github.com/google/nftables/expr"
 	"github.com/mdlayher/netlink"
 	"golang.org/x/sys/unix"
 )
 
-const (
-	NFTA_OBJ_USERDATA = 8
-	NFT_OBJECT_QUOTA  = 2
-)
-
 type QuotaObj struct {
 	Table    *Table
 	Name     string
@@ -63,7 +59,7 @@ func (q *QuotaObj) marshal(data bool) ([]byte, error) {
 	attrs := []netlink.Attribute{
 		{Type: unix.NFTA_OBJ_TABLE, Data: []byte(q.Table.Name + "\x00")},
 		{Type: unix.NFTA_OBJ_NAME, Data: []byte(q.Name + "\x00")},
-		{Type: unix.NFTA_OBJ_TYPE, Data: binaryutil.BigEndian.PutUint32(NFT_OBJECT_QUOTA)},
+		{Type: unix.NFTA_OBJ_TYPE, Data: binaryutil.BigEndian.PutUint32(unix.NFT_OBJECT_QUOTA)},
 	}
 	if data {
 		attrs = append(attrs, netlink.Attribute{Type: unix.NLA_F_NESTED | unix.NFTA_OBJ_DATA, Data: obj})
@@ -78,3 +74,19 @@ func (q *QuotaObj) table() *Table {
 func (q *QuotaObj) family() TableFamily {
 	return q.Table.Family
 }
+
+func (q *QuotaObj) data() expr.Any {
+	return &expr.Quota{
+		Bytes:    q.Bytes,
+		Consumed: q.Consumed,
+		Over:     q.Over,
+	}
+}
+
+func (q *QuotaObj) name() string {
+	return q.Name
+}
+
+func (q *QuotaObj) objType() ObjType {
+	return ObjTypeQuota
+}

set.go

@@ -321,7 +321,7 @@ func (s *SetElement) decode(fam byte) func(b []byte) error {
 			case unix.NFTA_SET_ELEM_EXPIRATION:
 				s.Expires = time.Millisecond * time.Duration(ad.Uint64())
 			case unix.NFTA_SET_ELEM_EXPR:
-				elems, err := parseexprfunc.ParseExprBytesFunc(fam, ad, ad.Bytes())
+				elems, err := parseexprfunc.ParseExprBytesFunc(fam, ad)
 				if err != nil {
 					return err
 				}