Address review suggestions

conn.go

@@ -232,9 +232,20 @@ func (cc *Conn) CloseLasting() error {
 }
 
 // Flush sends all buffered commands in a single batch to nftables.
-// If an optional gen ID is provided, it will be used in the batch begin message.
-// If the gen ID is not matched by the kernel, it will return an ERESTART error.
-func (cc *Conn) Flush(genID ...uint32) error {
+func (cc *Conn) Flush() error {
+	return cc.flush(0)
+}
+
+// FlushWithGenID sends all buffered commands in a single batch to nftables
+// along with the provided gen ID. If the ruleset has changed since the gen ID
+// was retrieved, an ERESTART error will be returned.
+func (cc *Conn) FlushWithGenID(genID uint32) error {
+	return cc.flush(genID)
+}
+
+// flush sends all buffered commands in a single batch to nftables. If genID is
+// non-zero, it will be included in the batch messages.
+func (cc *Conn) flush(genID uint32) error {
 	cc.mu.Lock()
 	defer func() {
 		cc.messages = nil
@@ -261,7 +272,7 @@ func (cc *Conn) Flush(genID ...uint32) error {
 		return err
 	}
 
-	batch, err := batch(cc.messages, genID...)
+	batch, err := batch(cc.messages, genID)
 	if err != nil {
 		return err
 	}
@@ -395,17 +406,17 @@ func (cc *Conn) marshalExpr(fam byte, e expr.Any) []byte {
 	return b
 }
 
-// Batch wraps the given messages in a batch begin and end message, and returns
-// the resulting slice of netlink messages. If a genID is provided, it is
+// batch wraps the given messages in a batch begin and end message, and returns
+// the resulting slice of netlink messages. If the genID is non-zero, it will be
 // included in both batch messages.
-func batch(messages []netlinkMessage, genID ...uint32) ([]netlink.Message, error) {
+func batch(messages []netlinkMessage, genID uint32) ([]netlink.Message, error) {
 	batch := make([]netlink.Message, len(messages)+2)
 
 	data := extraHeader(0, unix.NFNL_SUBSYS_NFTABLES)
 
-	if len(genID) > 0 && genID[0] > 0 {
+	if genID > 0 {
 		attr, err := netlink.MarshalAttributes([]netlink.Attribute{
-			{Type: unix.NFNL_BATCH_GENID, Data: binaryutil.BigEndian.PutUint32(genID[0])},
+			{Type: unix.NFNL_BATCH_GENID, Data: binaryutil.BigEndian.PutUint32(genID)},
 		})
 		if err != nil {
 			return nil, err

gen.go

@@ -14,6 +14,7 @@ type Gen struct {
 	ProcComm string // [16]byte - max 16bytes - kernel TASK_COMM_LEN
 }
 
+// Deprecated: GenMsg is an inconsistent old name for Gen. Prefer using Gen.
 type GenMsg = Gen
 
 const genHeaderType = netlink.HeaderType((unix.NFNL_SUBSYS_NFTABLES << 8) | unix.NFT_MSG_NEWGEN)

nftables_test.go

@@ -7493,7 +7493,7 @@ func TestFlushWithGenID(t *testing.T) {
 		Family: nftables.TableFamilyIPv4,
 	})
 
-	err = conn.Flush(gen.ID)
+	err = conn.FlushWithGenID(gen.ID)
 	if err == nil || !errors.Is(err, syscall.ERESTART) {
 		t.Errorf("expected error to be ERESTART, got: %v", err)
 	}