303 lines
8.0 KiB
Go
303 lines
8.0 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 nftables
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import (
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"sync"
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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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type MonitorAction uint8
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// Possible MonitorAction values.
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const (
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MonitorActionNew MonitorAction = 1 << iota
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MonitorActionDel
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MonitorActionMask MonitorAction = (1 << iota) - 1
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MonitorActionAny MonitorAction = MonitorActionMask
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)
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type MonitorObject uint32
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// Possible MonitorObject values.
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const (
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MonitorObjectTables MonitorObject = 1 << iota
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MonitorObjectChains
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MonitorObjectSets
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MonitorObjectRules
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MonitorObjectElements
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MonitorObjectRuleset
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MonitorObjectMask MonitorObject = (1 << iota) - 1
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MonitorObjectAny MonitorObject = MonitorObjectMask
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)
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var (
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monitorFlags map[MonitorAction]map[MonitorObject]uint32
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monitorFlagsInitOnce sync.Once
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)
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// A lazy init function to define flags.
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func lazyInit() {
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monitorFlagsInitOnce.Do(func() {
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monitorFlags = map[MonitorAction]map[MonitorObject]uint32{
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MonitorActionAny: {
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MonitorObjectAny: 0xffffffff,
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MonitorObjectTables: 1<<unix.NFT_MSG_NEWTABLE | 1<<unix.NFT_MSG_DELCHAIN,
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MonitorObjectChains: 1<<unix.NFT_MSG_NEWCHAIN | 1<<unix.NFT_MSG_DELCHAIN,
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MonitorObjectRules: 1<<unix.NFT_MSG_NEWRULE | 1<<unix.NFT_MSG_DELRULE,
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MonitorObjectSets: 1<<unix.NFT_MSG_NEWSET | 1<<unix.NFT_MSG_DELSET,
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MonitorObjectElements: 1<<unix.NFT_MSG_NEWSETELEM | 1<<unix.NFT_MSG_DELSETELEM,
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MonitorObjectRuleset: 1<<unix.NFT_MSG_NEWTABLE | 1<<unix.NFT_MSG_DELCHAIN |
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1<<unix.NFT_MSG_NEWCHAIN | 1<<unix.NFT_MSG_DELCHAIN |
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1<<unix.NFT_MSG_NEWRULE | 1<<unix.NFT_MSG_DELRULE |
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1<<unix.NFT_MSG_NEWSET | 1<<unix.NFT_MSG_DELSET |
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1<<unix.NFT_MSG_NEWSETELEM | 1<<unix.NFT_MSG_DELSETELEM |
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1<<unix.NFT_MSG_NEWOBJ | 1<<unix.NFT_MSG_DELOBJ,
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},
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MonitorActionNew: {
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MonitorObjectAny: 1<<unix.NFT_MSG_NEWTABLE |
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1<<unix.NFT_MSG_NEWCHAIN |
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1<<unix.NFT_MSG_NEWRULE |
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1<<unix.NFT_MSG_NEWSET |
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1<<unix.NFT_MSG_NEWSETELEM,
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MonitorObjectTables: 1 << unix.NFT_MSG_NEWTABLE,
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MonitorObjectChains: 1 << unix.NFT_MSG_NEWCHAIN,
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MonitorObjectRules: 1 << unix.NFT_MSG_NEWRULE,
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MonitorObjectSets: 1 << unix.NFT_MSG_NEWSET,
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MonitorObjectRuleset: 1<<unix.NFT_MSG_NEWTABLE |
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1<<unix.NFT_MSG_NEWCHAIN |
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1<<unix.NFT_MSG_NEWRULE |
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1<<unix.NFT_MSG_NEWSET |
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1<<unix.NFT_MSG_NEWSETELEM |
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1<<unix.NFT_MSG_NEWOBJ,
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},
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MonitorActionDel: {
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MonitorObjectAny: 1<<unix.NFT_MSG_DELTABLE |
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1<<unix.NFT_MSG_DELCHAIN |
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1<<unix.NFT_MSG_DELRULE |
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1<<unix.NFT_MSG_DELSET |
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1<<unix.NFT_MSG_DELSETELEM |
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1<<unix.NFT_MSG_DELOBJ,
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},
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}
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})
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}
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type EventType int
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const (
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EventTypeNewTable EventType = unix.NFT_MSG_NEWTABLE
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EventTypeDelTable EventType = unix.NFT_MSG_DELTABLE
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EventTypeNewChain EventType = unix.NFT_MSG_NEWCHAIN
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EventTypeDELChain EventType = unix.NFT_MSG_DELCHAIN
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EventTypeNewRule EventType = unix.NFT_MSG_NEWRULE
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EventTypeDelRule EventType = unix.NFT_MSG_DELRULE
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EventTypeNewSet EventType = unix.NFT_MSG_NEWSET
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EventTypeDelSet EventType = unix.NFT_MSG_DELSET
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EventTypeNewSetElem EventType = unix.NFT_MSG_NEWSETELEM
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EventTypeDelSetElem EventType = unix.NFT_MSG_DELSETELEM
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EventTypeNewObj EventType = unix.NFT_MSG_NEWOBJ
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EventTypeDelObj EventType = unix.NFT_MSG_DELOBJ
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)
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type Event struct {
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Type EventType
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Data interface{}
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Error error
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}
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const (
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monitorOK = iota
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monitorClosed
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)
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// A Monitor to track actions on objects.
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type Monitor struct {
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action MonitorAction
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object MonitorObject
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monitorFlags uint32
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// mtx covers eventCh and status
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mtx sync.Mutex
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eventCh chan *Event
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status int
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conn *netlink.Conn
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closer netlinkCloser
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}
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type MonitorOption func(*Monitor)
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func WithMonitorEventBuffer(size int) MonitorOption {
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return func(monitor *Monitor) {
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monitor.eventCh = make(chan *Event, size)
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}
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}
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// WithMonitorAction to set monitor actions like new, del or any.
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func WithMonitorAction(action MonitorAction) MonitorOption {
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return func(monitor *Monitor) {
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monitor.action = action
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}
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}
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// WithMonitorObject to set monitor objects.
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func WithMonitorObject(object MonitorObject) MonitorOption {
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return func(monitor *Monitor) {
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monitor.object = object
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}
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}
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// NewMonitor returns a Monitor with options to be started.
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func NewMonitor(opts ...MonitorOption) *Monitor {
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lazyInit()
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monitor := &Monitor{
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status: monitorOK,
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}
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for _, opt := range opts {
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opt(monitor)
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}
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if monitor.eventCh == nil {
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monitor.eventCh = make(chan *Event)
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}
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objects, ok := monitorFlags[monitor.action]
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if !ok {
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objects = monitorFlags[MonitorActionAny]
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}
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flags, ok := objects[monitor.object]
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if !ok {
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flags = objects[MonitorObjectAny]
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}
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monitor.monitorFlags = flags
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return monitor
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}
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func (monitor *Monitor) monitor() {
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for {
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msgs, err := monitor.conn.Receive()
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if err != nil {
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break
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}
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for _, msg := range msgs {
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if got, want := msg.Header.Type&0xff00>>8, netlink.HeaderType(unix.NFNL_SUBSYS_NFTABLES); got != want {
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continue
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}
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msgType := msg.Header.Type & 0x00ff
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if monitor.monitorFlags&1<<msgType == 0 {
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continue
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}
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switch msgType {
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case unix.NFT_MSG_NEWTABLE, unix.NFT_MSG_DELTABLE:
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table, err := tableFromMsg(msg)
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event := &Event{
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Type: EventType(msgType),
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Data: table,
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Error: err,
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}
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monitor.eventCh <- event
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case unix.NFT_MSG_NEWCHAIN, unix.NFT_MSG_DELCHAIN:
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chain, err := chainFromMsg(msg)
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event := &Event{
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Type: EventType(msgType),
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Data: chain,
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Error: err,
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}
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monitor.eventCh <- event
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case unix.NFT_MSG_NEWRULE, unix.NFT_MSG_DELRULE:
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rule, err := parseRuleFromMsg(msg)
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event := &Event{
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Type: EventType(msgType),
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Data: rule,
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Error: err,
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}
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monitor.eventCh <- event
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case unix.NFT_MSG_NEWSET, unix.NFT_MSG_DELSET:
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set, err := setsFromMsg(msg)
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event := &Event{
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Type: EventType(msgType),
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Data: set,
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Error: err,
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}
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monitor.eventCh <- event
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case unix.NFT_MSG_NEWSETELEM, unix.NFT_MSG_DELSETELEM:
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elems, err := elementsFromMsg(uint8(TableFamilyUnspecified), msg)
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event := &Event{
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Type: EventType(msgType),
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Data: elems,
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Error: err,
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}
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monitor.eventCh <- event
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case unix.NFT_MSG_NEWOBJ, unix.NFT_MSG_DELOBJ:
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obj, err := objFromMsg(msg)
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event := &Event{
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Type: EventType(msgType),
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Data: obj,
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Error: err,
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}
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monitor.eventCh <- event
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case unix.NFT_MSG_TRACE:
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}
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}
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}
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monitor.mtx.Lock()
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if monitor.status != monitorClosed {
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monitor.status = monitorClosed
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monitor.closer()
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close(monitor.eventCh)
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}
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monitor.mtx.Unlock()
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}
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func (monitor *Monitor) Close() {
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monitor.mtx.Lock()
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if monitor.status != monitorClosed {
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monitor.status = monitorClosed
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monitor.closer()
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close(monitor.eventCh)
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}
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monitor.mtx.Unlock()
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}
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// AddMonitor to perform the monitor immediately. The channel will be closed after
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// calling Close on Monitor or encountering a netlink conn error while Receive.
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func (cc *Conn) AddMonitor(monitor *Monitor) (chan *Event, error) {
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conn, closer, err := cc.netlinkConn()
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if err != nil {
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return nil, err
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}
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monitor.conn = conn
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monitor.closer = closer
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if monitor.monitorFlags != 0 {
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err = conn.JoinGroup(uint32(unix.NFNLGRP_NFTABLES))
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if err != nil {
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monitor.closer()
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return nil, err
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}
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conn.JoinGroup(uint32(unix.NFNLGRP_NFTRACE))
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}
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go monitor.monitor()
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return monitor.eventCh, nil
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}
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func parseRuleFromMsg(msg netlink.Message) (*Rule, error) {
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genmsg := &NFGenMsg{}
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genmsg.Decode(msg.Data[:4])
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return ruleFromMsg(TableFamily(genmsg.NFGenFamily), msg)
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}
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