From 9d863e8ebf85de4d09f98d69f094186a9ad6966b Mon Sep 17 00:00:00 2001
From: h4l0gen <ks3913688@gmail.com>
Date: Wed, 20 Mar 2024 23:41:09 +0530
Subject: [PATCH] adding an event on interpreted procs inbound network activity

Signed-off-by: h4l0gen <ks3913688@gmail.com>

adding an event on interpreted procs inbound network activity

Signed-off-by: h4l0gen <ks3913688@gmail.com>

commits squashed

Signed-off-by: h4l0gen <ks3913688@gmail.com>
---
 events/helper/inbound_connection.go           | 63 +++++++++++++++++++
 .../interpreted_inbound_network_activity.go   | 28 +++++++++
 2 files changed, 91 insertions(+)
 create mode 100644 events/helper/inbound_connection.go
 create mode 100644 events/syscall/interpreted_inbound_network_activity.go

diff --git a/events/helper/inbound_connection.go b/events/helper/inbound_connection.go
new file mode 100644
index 00000000..d2f17435
--- /dev/null
+++ b/events/helper/inbound_connection.go
@@ -0,0 +1,63 @@
+// SPDX-License-Identifier: Apache-2.0
+/*
+Copyright (C) 2023 The Falco Authors.
+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 helper
+
+import (
+	"fmt"
+	"net"
+
+	"github.com/falcosecurity/event-generator/events"
+)
+
+var _ = events.Register(InboundConnection)
+
+func InboundConnection(h events.Helper) error {
+	address, _ := getRandomLocalAddress()
+	listener, err := net.Listen("tcp", address)
+	if err != nil {
+		return err
+	}
+	fmt.Println("Server started on", address)
+	defer listener.Close()
+	fmt.Println("Server closed on", address)
+	return nil
+}
+
+func getRandomLocalAddress() (string, error) {
+	addrs, err := net.InterfaceAddrs()
+	if err != nil {
+		return "", err
+	}
+	for _, addr := range addrs {
+		ipNet, ok := addr.(*net.IPNet)
+		if !ok {
+			continue
+		}
+		if ipNet.IP.IsLoopback() || ipNet.IP.IsUnspecified() {
+			continue
+		}
+		ip := ipNet.IP.To4()
+		if ip == nil {
+			continue
+		}
+		listener, err := net.ListenTCP("tcp4", &net.TCPAddr{IP: ip})
+		if err != nil {
+			continue
+		}
+		listener.Close()
+		return fmt.Sprintf("%s:%d", ip, listener.Addr().(*net.TCPAddr).Port), nil
+	}
+	return "", fmt.Errorf("no valid local address found")
+}
diff --git a/events/syscall/interpreted_inbound_network_activity.go b/events/syscall/interpreted_inbound_network_activity.go
new file mode 100644
index 00000000..deaae373
--- /dev/null
+++ b/events/syscall/interpreted_inbound_network_activity.go
@@ -0,0 +1,28 @@
+// SPDX-License-Identifier: Apache-2.0
+/*
+Copyright (C) 2024 The Falco Authors.
+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 syscall
+
+import (
+	"github.com/falcosecurity/event-generator/events"
+)
+
+var _ = events.Register(
+	InterpretedProcsInboundNetworkActivity,
+	events.WithDisabled(), // this rule is not included in falco_rules.yaml (stable rules), so disable the action
+)
+
+func InterpretedProcsInboundNetworkActivity(h events.Helper) error {
+	return h.SpawnAs("lua", "helper.InboundConnection")
+}