79 lines
2.2 KiB
Go
79 lines
2.2 KiB
Go
// Copyright 2018 Google LLC. All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package expr
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import (
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"encoding/binary"
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"fmt"
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"github.com/google/nftables/binaryutil"
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"github.com/mdlayher/netlink"
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"golang.org/x/sys/unix"
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)
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// Numgen defines Numgen expression structure
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type Numgen struct {
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Register uint32
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Modulus uint32
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Type uint32
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Offset uint32
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}
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func (e *Numgen) marshal() ([]byte, error) {
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// Currently only two types are supported, failing if Type is not of two known types
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switch e.Type {
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case unix.NFT_NG_INCREMENTAL:
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case unix.NFT_NG_RANDOM:
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default:
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return nil, fmt.Errorf("unsupported numgen type %d", e.Type)
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}
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data, err := netlink.MarshalAttributes([]netlink.Attribute{
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{Type: unix.NFTA_NG_DREG, Data: binaryutil.BigEndian.PutUint32(e.Register)},
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{Type: unix.NFTA_NG_MODULUS, Data: binaryutil.BigEndian.PutUint32(e.Modulus)},
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{Type: unix.NFTA_NG_TYPE, Data: binaryutil.BigEndian.PutUint32(e.Type)},
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{Type: unix.NFTA_NG_OFFSET, Data: binaryutil.BigEndian.PutUint32(e.Offset)},
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})
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if err != nil {
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return nil, err
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}
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return netlink.MarshalAttributes([]netlink.Attribute{
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{Type: unix.NFTA_EXPR_NAME, Data: []byte("numgen\x00")},
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{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: data},
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})
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}
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func (e *Numgen) unmarshal(data []byte) error {
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ad, err := netlink.NewAttributeDecoder(data)
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if err != nil {
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return err
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}
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ad.ByteOrder = binary.BigEndian
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for ad.Next() {
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switch ad.Type() {
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case unix.NFTA_NG_DREG:
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e.Register = ad.Uint32()
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case unix.NFTA_NG_MODULUS:
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e.Modulus = ad.Uint32()
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case unix.NFTA_NG_TYPE:
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e.Type = ad.Uint32()
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case unix.NFTA_NG_OFFSET:
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e.Offset = ad.Uint32()
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}
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}
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return ad.Err()
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}
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