From e3f6fbfa5f6567d4f3f824b5a9ef69acab21a5de Mon Sep 17 00:00:00 2001
From: singchia <singchia@163.com>
Date: Sat, 13 May 2023 20:58:06 -0400
Subject: [PATCH] feat: add Monitor definiation Committer: singchia
 <singchia@163.com>

---
 monitor.go | 122 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 122 insertions(+)
 create mode 100644 monitor.go

diff --git a/monitor.go b/monitor.go
new file mode 100644
index 0000000..b622315
--- /dev/null
+++ b/monitor.go
@@ -0,0 +1,122 @@
+// 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 nftables
+
+import (
+	"sync"
+
+	"golang.org/x/sys/unix"
+)
+
+type MonitorEvent uint8
+
+const (
+	MonitorEventNew MonitorEvent = 1 << iota
+	MonitorEventDel
+	MonitorEventMask MonitorEvent = (1 << iota) - 1
+	MonitorEventAny  MonitorEvent = MonitorEventMask
+)
+
+type MonitorObject uint32
+
+// Possible MonitorObject values.
+const (
+	MonitorObjectTables MonitorObject = 1 << iota
+	MonitorObjectChains
+	MonitorObjectSets
+	MonitorObjectRules
+	MonitorObjectElements
+	MonitorObjectRuleset
+	MonitorObjectTrace
+	MonitorObjectMask MonitorObject = (1 << iota) - 1
+	MonitorObjectAny  MonitorObject = MonitorObjectMask
+)
+
+var (
+	monitorFlags         map[MonitorEvent]map[MonitorObject]uint32
+	monitorFlagsInitOnce sync.Once
+)
+
+func lazyInitOnce() {
+	monitorFlagsInitOnce.Do(func() {
+		monitorFlags = map[MonitorEvent]map[MonitorObject]uint32{
+			MonitorEventAny: {
+				MonitorObjectAny:      0xffffffff,
+				MonitorObjectTables:   1<<unix.NFT_MSG_NEWTABLE | 1<<unix.NFT_MSG_DELCHAIN,
+				MonitorObjectChains:   1<<unix.NFT_MSG_NEWCHAIN | 1<<unix.NFT_MSG_DELCHAIN,
+				MonitorObjectRules:    1<<unix.NFT_MSG_NEWRULE | 1<<unix.NFT_MSG_DELRULE,
+				MonitorObjectSets:     1<<unix.NFT_MSG_NEWSET | 1<<unix.NFT_MSG_DELSET,
+				MonitorObjectElements: 1<<unix.NFT_MSG_NEWSETELEM | 1<<unix.NFT_MSG_DELSETELEM,
+				MonitorObjectRuleset: 1<<unix.NFT_MSG_NEWTABLE | 1<<unix.NFT_MSG_DELCHAIN |
+					1<<unix.NFT_MSG_NEWCHAIN | 1<<unix.NFT_MSG_DELCHAIN |
+					1<<unix.NFT_MSG_NEWRULE | 1<<unix.NFT_MSG_DELRULE |
+					1<<unix.NFT_MSG_NEWSET | 1<<unix.NFT_MSG_DELSET |
+					1<<unix.NFT_MSG_NEWSETELEM | 1<<unix.NFT_MSG_DELSETELEM |
+					1<<unix.NFT_MSG_NEWOBJ | 1<<unix.NFT_MSG_DELOBJ,
+				MonitorObjectTrace: 1 << unix.NFT_MSG_TRACE,
+			},
+			MonitorEventNew: {
+				MonitorObjectAny: 1<<unix.NFT_MSG_NEWTABLE |
+					1<<unix.NFT_MSG_NEWCHAIN |
+					1<<unix.NFT_MSG_NEWRULE |
+					1<<unix.NFT_MSG_NEWSET |
+					1<<unix.NFT_MSG_NEWSETELEM,
+				MonitorObjectTables: 1 << unix.NFT_MSG_NEWTABLE,
+				MonitorObjectChains: 1 << unix.NFT_MSG_NEWCHAIN,
+				MonitorObjectRules:  1 << unix.NFT_MSG_NEWRULE,
+				MonitorObjectSets:   1 << unix.NFT_MSG_NEWSET,
+				MonitorObjectRuleset: 1<<unix.NFT_MSG_NEWTABLE |
+					1<<unix.NFT_MSG_NEWCHAIN |
+					1<<unix.NFT_MSG_NEWRULE |
+					1<<unix.NFT_MSG_NEWSET |
+					1<<unix.NFT_MSG_NEWSETELEM |
+					1<<unix.NFT_MSG_NEWOBJ,
+				MonitorObjectTrace: 0,
+			},
+			MonitorEventDel: {
+				MonitorObjectAny: 1<<unix.NFT_MSG_DELTABLE |
+					1<<unix.NFT_MSG_DELCHAIN |
+					1<<unix.NFT_MSG_DELRULE |
+					1<<unix.NFT_MSG_DELSET |
+					1<<unix.NFT_MSG_DELSETELEM |
+					1<<unix.NFT_MSG_DELOBJ,
+				MonitorObjectTrace: 0,
+			},
+		}
+	})
+}
+
+type Monitor struct {
+	Event      MonitorEvent
+	Object     MonitorObject
+	BufferSize int
+}
+
+func (monitor *Monitor) AddMonitorObject(obj MonitorObject) {
+	monitor.Object = monitor.Object | obj
+}
+
+type Event struct{}
+
+func (cc *Conn) AddMonitor(monitor *Monitor) (chan *Event, error) {
+	_, closer, err := cc.netlinkConn()
+	if err != nil {
+		return nil, err
+	}
+	defer func() { _ = closer() }()
+
+	ch := make(chan *Event, monitor.BufferSize)
+	return ch, nil
+}