Merge a8e056d949 into aa8348f790

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

obj.go

@@ -69,6 +69,9 @@ type Obj interface {
 	objType() ObjType
 }
 
+// ObjAttr represents nftables stateful object attributes
+// Corresponds to netfilter nft_object_attributes as per
+// https://git.netfilter.org/libnftnl/tree/include/linux/netfilter/nf_tables.h?id=116e95aa7b6358c917de8c69f6f173874030b46b#n1626
 type ObjAttr struct {
 	Table *Table
 	Name  string
@@ -154,17 +157,32 @@ 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
+// This function will determine whether returned object will be
+// one of legacy types QuotaObj/CounterObj or the new ObjAttr
+// type struct based passed o parameter type
+// If o is of type ObjAttr, the implementation will work with
+// the new ObjAttr type, otherwise falls back to legacy QuotaObj/CounterObj
 func (cc *Conn) GetObj(o Obj) ([]Obj, error) {
 	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
+// This function will determine whether returned object will be
+// one of legacy types QuotaObj/CounterObj or the new ObjAttr
+// type struct based passed o parameter type
+// If o is of type ObjAttr, the implementation will work with
+// the new ObjAttr type, otherwise falls back to legacy QuotaObj/CounterObj
 func (cc *Conn) GetObjReset(o Obj) ([]Obj, error) {
 	return cc.getObjWithLegacyType(nil, o.table(), unix.NFT_MSG_GETOBJ_RESET, cc.useLegacyObjType(o))
 }
 
 // GetObject gets the specified Object
+// This function will determine whether returned object will be
+// one of legacy types QuotaObj/CounterObj or the new ObjAttr
+// type struct based passed o parameter type
+// If o is of type ObjAttr, the implementation will work with
+// the new ObjAttr type, otherwise falls back to legacy QuotaObj/CounterObj
 func (cc *Conn) GetObject(o Obj) (Obj, error) {
 	objs, err := cc.getObj(o, o.table(), unix.NFT_MSG_GETOBJ)
 
@@ -176,11 +194,18 @@ func (cc *Conn) GetObject(o Obj) (Obj, error) {
 }
 
 // GetObjects get all the Obj that belongs to the given table
+// This function will always return legacy QuotaObj/CounterObj
+// types for backwards compatibility
 func (cc *Conn) GetObjects(t *Table) ([]Obj, error) {
 	return cc.getObj(nil, t, unix.NFT_MSG_GETOBJ)
 }
 
 // ResetObject reset the given Obj
+// This function will determine whether returned object will be
+// one of legacy types QuotaObj/CounterObj or the new ObjAttr
+// type struct based passed o parameter type
+// If o is of type ObjAttr, the implementation will work with
+// the new ObjAttr type, otherwise falls back to legacy QuotaObj/CounterObj
 func (cc *Conn) ResetObject(o Obj) (Obj, error) {
 	objs, err := cc.getObj(o, o.table(), unix.NFT_MSG_GETOBJ_RESET)
 
@@ -192,6 +217,8 @@ func (cc *Conn) ResetObject(o Obj) (Obj, error) {
 }
 
 // ResetObjects reset all the Obj that belongs to the given table
+// This function will always return legacy QuotaObj/CounterObj
+// types for backwards compatibility
 func (cc *Conn) ResetObjects(t *Table) ([]Obj, error) {
 	return cc.getObj(nil, t, unix.NFT_MSG_GETOBJ_RESET)
 }
@@ -219,61 +246,30 @@ func objFromMsg(msg netlink.Message, returnLegacyType bool) (Obj, error) {
 		case unix.NFTA_OBJ_TYPE:
 			objectType = ad.Uint32()
 		case unix.NFTA_OBJ_DATA:
-			if !returnLegacyType {
+			if returnLegacyType {
-				o := ObjAttr{
+				return objDataFromMsgLegacy(ad, table, name, objectType)
-					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 {
+			o := ObjAttr{
-			case unix.NFT_OBJECT_COUNTER:
+				Table: table,
-				o := CounterObj{
+				Name:  name,
-					Table: table,
+				Type:  ObjType(objectType),
-					Name:  name,
-				}
-
-				ad.Do(func(b []byte) error {
-					ad, err := netlink.NewAttributeDecoder(b)
-					if err != nil {
-						return err
-					}
-					ad.ByteOrder = binary.BigEndian
-					return o.unmarshal(ad)
-				})
-				return &o, ad.Err()
-			case unix.NFT_OBJECT_QUOTA:
-				o := QuotaObj{
-					Table: table,
-					Name:  name,
-				}
-
-				ad.Do(func(b []byte) error {
-					ad, err := netlink.NewAttributeDecoder(b)
-					if err != nil {
-						return err
-					}
-					ad.ByteOrder = binary.BigEndian
-					return o.unmarshal(ad)
-				})
-				return &o, ad.Err()
 			}
+
+			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()
 		}
 	}
 	if err := ad.Err(); err != nil {
@@ -282,6 +278,45 @@ func objFromMsg(msg netlink.Message, returnLegacyType bool) (Obj, error) {
 	return nil, fmt.Errorf("malformed stateful object")
 }
 
+func objDataFromMsgLegacy(ad *netlink.AttributeDecoder, table *Table, name string, objectType uint32) (Obj, error) {
+	switch objectType {
+	case unix.NFT_OBJECT_COUNTER:
+		o := CounterObj{
+			Table: table,
+			Name:  name,
+		}
+
+		ad.Do(func(b []byte) error {
+			ad, err := netlink.NewAttributeDecoder(b)
+			if err != nil {
+				return err
+			}
+			ad.ByteOrder = binary.BigEndian
+			return o.unmarshal(ad)
+		})
+		return &o, ad.Err()
+	case unix.NFT_OBJECT_QUOTA:
+		o := QuotaObj{
+			Table: table,
+			Name:  name,
+		}
+
+		ad.Do(func(b []byte) error {
+			ad, err := netlink.NewAttributeDecoder(b)
+			if err != nil {
+				return err
+			}
+			ad.ByteOrder = binary.BigEndian
+			return o.unmarshal(ad)
+		})
+		return &o, ad.Err()
+	}
+	if err := ad.Err(); err != nil {
+		return nil, err
+	}
+	return nil, fmt.Errorf("malformed stateful object")
+}
+
 func (cc *Conn) getObj(o Obj, t *Table, msgType uint16) ([]Obj, error) {
 	return cc.getObjWithLegacyType(o, t, msgType, cc.useLegacyObjType(o))
 }