Implement Queue Expr (#8)

expr/queue.go

@@ -0,0 +1,82 @@
+// Copyright 2018 Google LLC. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package expr
+
+import (
+	"encoding/binary"
+
+	"github.com/google/nftables/binaryutil"
+	"github.com/mdlayher/netlink"
+	"golang.org/x/sys/unix"
+)
+
+type QueueAttribute uint16
+
+type QueueFlag uint16
+
+// Possible QueueAttribute values
+const (
+	QueueNum   QueueAttribute = unix.NFTA_QUEUE_NUM
+	QueueTotal QueueAttribute = unix.NFTA_QUEUE_TOTAL
+	QueueFlags QueueAttribute = unix.NFTA_QUEUE_FLAGS
+
+	// TODO: get into x/sys/unix
+	QueueFlagBypass QueueFlag = 0x01
+	QueueFlagFanout QueueFlag = 0x02
+	QueueFlagMask   QueueFlag = 0x03
+)
+
+type Queue struct {
+	Num   uint16
+	Total uint16
+	Flag  QueueFlag
+}
+
+func (e *Queue) marshal() ([]byte, error) {
+	if e.Total == 0 {
+		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
+	}
+	return netlink.MarshalAttributes([]netlink.Attribute{
+		{Type: unix.NFTA_EXPR_NAME, Data: []byte("queue\x00")},
+		{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: data},
+	})
+}
+
+func (e *Queue) unmarshal(data []byte) error {
+	ad, err := netlink.NewAttributeDecoder(data)
+	if err != nil {
+		return err
+	}
+	ad.ByteOrder = binary.BigEndian
+	for ad.Next() {
+		switch ad.Type() {
+		case unix.NFTA_QUEUE_NUM:
+			e.Num = ad.Uint16()
+		case unix.NFTA_QUEUE_TOTAL:
+			e.Total = ad.Uint16()
+		case unix.NFTA_QUEUE_FLAGS:
+			e.Flag = QueueFlag(ad.Uint16())
+		}
+	}
+	return ad.Err()
+}