133 lines
3.5 KiB
Go
133 lines
3.5 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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"errors"
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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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// LimitType represents the type of the limit expression.
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type LimitType uint32
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// Imported from the nft_limit_type enum in netfilter/nf_tables.h.
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const (
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LimitTypePkts LimitType = unix.NFT_LIMIT_PKTS
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LimitTypePktBytes LimitType = unix.NFT_LIMIT_PKT_BYTES
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)
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// LimitTime represents the limit unit.
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type LimitTime uint64
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// Possible limit unit values.
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const (
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LimitTimeSecond LimitTime = 1
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LimitTimeMinute LimitTime = 60
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LimitTimeHour LimitTime = 60 * 60
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LimitTimeDay LimitTime = 60 * 60 * 24
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LimitTimeWeek LimitTime = 60 * 60 * 24 * 7
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)
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func limitTime(value uint64) (LimitTime, error) {
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switch LimitTime(value) {
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case LimitTimeSecond:
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return LimitTimeSecond, nil
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case LimitTimeMinute:
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return LimitTimeMinute, nil
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case LimitTimeHour:
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return LimitTimeHour, nil
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case LimitTimeDay:
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return LimitTimeDay, nil
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case LimitTimeWeek:
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return LimitTimeWeek, nil
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default:
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return 0, fmt.Errorf("expr: invalid limit unit value %d", value)
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}
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}
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// Limit represents a rate limit expression.
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type Limit struct {
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Type LimitType
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Rate uint64
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Over bool
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Unit LimitTime
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Burst uint32
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}
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func (l *Limit) marshal(fam byte) ([]byte, error) {
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data, err := l.marshalData(fam)
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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("limit\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 (l *Limit) marshalData(fam byte) ([]byte, error) {
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var flags uint32
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if l.Over {
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flags = unix.NFT_LIMIT_F_INV
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}
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attrs := []netlink.Attribute{
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{Type: unix.NFTA_LIMIT_RATE, Data: binaryutil.BigEndian.PutUint64(l.Rate)},
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{Type: unix.NFTA_LIMIT_UNIT, Data: binaryutil.BigEndian.PutUint64(uint64(l.Unit))},
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{Type: unix.NFTA_LIMIT_BURST, Data: binaryutil.BigEndian.PutUint32(l.Burst)},
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{Type: unix.NFTA_LIMIT_TYPE, Data: binaryutil.BigEndian.PutUint32(uint32(l.Type))},
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{Type: unix.NFTA_LIMIT_FLAGS, Data: binaryutil.BigEndian.PutUint32(flags)},
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}
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return netlink.MarshalAttributes(attrs)
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}
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func (l *Limit) unmarshal(fam byte, 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_LIMIT_RATE:
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l.Rate = ad.Uint64()
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case unix.NFTA_LIMIT_UNIT:
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l.Unit, err = limitTime(ad.Uint64())
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if err != nil {
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return err
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}
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case unix.NFTA_LIMIT_BURST:
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l.Burst = ad.Uint32()
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case unix.NFTA_LIMIT_TYPE:
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l.Type = LimitType(ad.Uint32())
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if l.Type != LimitTypePkts && l.Type != LimitTypePktBytes {
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return fmt.Errorf("expr: invalid limit type %d", l.Type)
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}
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case unix.NFTA_LIMIT_FLAGS:
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l.Over = (ad.Uint32() & unix.NFT_LIMIT_F_INV) == 1
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default:
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return errors.New("expr: unhandled limit netlink attribute")
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}
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}
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return ad.Err()
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}
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