initial commit

.gitignore

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+pifi

Makefile

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+build:
+	env GOOS=linux GOARCH=arm64 go build -o pifi main.go
+
+upload:
+	scp pifi pi@rpi-40ac:/home/pi/pifi

README.md

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+# PiFi
+
+This is a simple tool to create and manage a hotspot on a Raspberry Pi (ARM64).  
+The code is based on https://github.com/NetworkManager/NetworkManager/blob/main/examples/python/dbus/wifi-hotspot.py
+and adds following features:
+
+- Environment variables or intput parameters for SSID and password
+- Option to remove the connection
+
+## Build
+
+```bash
+make build
+```
+
+## Usage
+
+```bash
+sudo ./pifi wlan0 up "My Hotspot" "my password"
+sudo ./pifi wlan0 down
+sudo ./pifi wlan0 remove
+```
+
+## Environment variables
+
+The hotspot will use the environment variables `WIFI_SSID` and `WIFI_PASSWORD` if they are set.
+
+```bash
+export WIFI_SSID="My Hotspot"
+export WIFI_PASSWORD="my password"
+
+sudo -E ./pifi wlan0 up
+```

go.mod

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+module dcentral/pifi
+
+go 1.23.4
+
+require github.com/godbus/dbus/v5 v5.1.0

go.sum

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+github.com/godbus/dbus/v5 v5.1.0 h1:4KLkAxT3aOY8Li4FRJe/KvhoNFFxo0m6fNuFUO8QJUk=
+github.com/godbus/dbus/v5 v5.1.0/go.mod h1:xhWf0FNVPg57R7Z0UbKHbJfkEywrmjJnf7w5xrFpKfA=

main.go

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+// Usage: go run hotspot.go <ifname> [up|down|remove] [ssid] [password]
+
+package main
+
+import (
+	"fmt"
+	"log"
+	"os"
+	"time"
+
+	"github.com/godbus/dbus/v5"
+)
+
+const (
+	ourUUID = "7d706027-727c-4d4c-a816-f0e1b99db8ab"
+)
+
+var (
+	defaultSSID     = "PIAP"
+	defaultPassword = "raspberry"
+)
+
+func usage() {
+	fmt.Printf("Usage: %s <ifname> [up|down|remove] [ssid] [password]\n", os.Args[0])
+	os.Exit(0)
+}
+
+func startAccessPoint(conn *dbus.Conn, connPath, devPath dbus.ObjectPath) error {
+	nmObj := conn.Object(
+		"org.freedesktop.NetworkManager",
+		"/org/freedesktop/NetworkManager",
+	)
+
+	// Activate the connection
+	var activePath dbus.ObjectPath
+	err := nmObj.
+		Call("org.freedesktop.NetworkManager.ActivateConnection", 0,
+			connPath, devPath, dbus.ObjectPath("/")).
+		Store(&activePath)
+	if err != nil {
+		return fmt.Errorf("ActivateConnection failed: %v", err)
+	}
+
+	// Wait until the connection is activated
+	props := conn.Object(
+		"org.freedesktop.NetworkManager",
+		activePath,
+	)
+
+	start := time.Now()
+	for time.Since(start) < 10*time.Second {
+		var stateVar dbus.Variant
+		err = props.
+			Call("org.freedesktop.DBus.Properties.Get", 0,
+				"org.freedesktop.NetworkManager.Connection.Active",
+				"State").
+			Store(&stateVar)
+		if err != nil {
+			return fmt.Errorf("Properties.Get(State) failed: %v", err)
+		}
+		if state, ok := stateVar.Value().(uint32); ok && state == 2 {
+			fmt.Println("Access point started")
+			return nil
+		}
+		time.Sleep(1 * time.Second)
+	}
+	return fmt.Errorf("failed to start access point")
+}
+
+func stopAccessPoint(conn *dbus.Conn, devPath dbus.ObjectPath) error {
+	devObj := conn.Object(
+		"org.freedesktop.NetworkManager",
+		devPath,
+	)
+	err := devObj.
+		Call("org.freedesktop.NetworkManager.Device.Disconnect", 0).
+		Err
+	if err != nil {
+		return fmt.Errorf("Device.Disconnect failed: %v", err)
+	}
+	fmt.Println("Access point stopped")
+	return nil
+}
+
+func removeConnection(conn *dbus.Conn, connPath dbus.ObjectPath) error {
+	connObj := conn.Object(
+		"org.freedesktop.NetworkManager",
+		connPath,
+	)
+	err := connObj.
+		Call("org.freedesktop.NetworkManager.Settings.Connection.Delete", 0).
+		Err
+	if err != nil {
+		return fmt.Errorf("Connection.Delete failed: %v", err)
+	}
+	fmt.Println("Connection removed")
+	return nil
+}
+
+func main() {
+	if len(os.Args) < 3 {
+		usage()
+	}
+	iface := os.Args[1]
+	op := os.Args[2]
+
+	// Get SSID and password from args, env vars or use defaults
+	ssid := defaultSSID
+	password := defaultPassword
+
+	// Check environment variables first
+	if v, ok := os.LookupEnv("WIFI_SSID"); ok {
+		ssid = v
+	}
+	if v, ok := os.LookupEnv("WIFI_PASSWORD"); ok {
+		password = v
+	}
+
+	// Command line args override environment variables
+	if op == "up" && len(os.Args) >= 5 {
+		ssid = os.Args[3]
+		password = os.Args[4]
+	}
+
+	// Connect to the system bus
+	conn, err := dbus.SystemBus()
+	if err != nil {
+		log.Fatalf("Failed to connect to system bus: %v", err)
+	}
+
+	// Get the Settings interface
+	settingsObj := conn.Object(
+		"org.freedesktop.NetworkManager",
+		"/org/freedesktop/NetworkManager/Settings",
+	)
+
+	// List existing connections
+	var paths []dbus.ObjectPath
+	err = settingsObj.
+		Call("org.freedesktop.NetworkManager.Settings.ListConnections", 0).
+		Store(&paths)
+	if err != nil {
+		log.Fatalf("ListConnections failed: %v", err)
+	}
+
+	// Look up our connection by UUID
+	var connPath dbus.ObjectPath
+	for _, p := range paths {
+		obj := conn.Object(
+			"org.freedesktop.NetworkManager",
+			p,
+		)
+		var cfg map[string]map[string]dbus.Variant
+		err = obj.
+			Call("org.freedesktop.NetworkManager.Settings.Connection.GetSettings", 0).
+			Store(&cfg)
+		if err != nil {
+			continue
+		}
+		if v, ok := cfg["connection"]["uuid"].Value().(string); ok && v == ourUUID {
+			connPath = p
+			break
+		}
+	}
+
+	// If not found, add it
+	if connPath == "" {
+		settingsMap := map[string]map[string]dbus.Variant{
+			"connection": {
+				"type":        dbus.MakeVariant("802-11-wireless"),
+				"uuid":        dbus.MakeVariant(ourUUID),
+				"id":          dbus.MakeVariant(ssid),
+				"autoconnect": dbus.MakeVariant(false),
+			},
+			"802-11-wireless": {
+				"ssid":    dbus.MakeVariant([]byte(ssid)),
+				"mode":    dbus.MakeVariant("ap"),
+				"band":    dbus.MakeVariant("bg"),
+				"channel": dbus.MakeVariant(uint32(1)),
+			},
+			"802-11-wireless-security": {
+				"key-mgmt": dbus.MakeVariant("wpa-psk"),
+				"psk":      dbus.MakeVariant(password),
+			},
+			"ipv4": {
+				"method": dbus.MakeVariant("shared"),
+			},
+			"ipv6": {
+				"method": dbus.MakeVariant("ignore"),
+			},
+		}
+
+		err = settingsObj.
+			Call("org.freedesktop.NetworkManager.Settings.AddConnection", 0, settingsMap).
+			Store(&connPath)
+		if err != nil {
+			log.Fatalf("AddConnection failed: %v", err)
+		}
+	}
+
+	// Get the NetworkManager interface
+	nmObj := conn.Object(
+		"org.freedesktop.NetworkManager",
+		"/org/freedesktop/NetworkManager",
+	)
+
+	// Find the device by interface name
+	var devPath dbus.ObjectPath
+	err = nmObj.
+		Call("org.freedesktop.NetworkManager.GetDeviceByIpIface", 0, iface).
+		Store(&devPath)
+	if err != nil {
+		log.Fatalf("GetDeviceByIpIface(%s) failed: %v", iface, err)
+	}
+
+	switch op {
+	case "up":
+		if err := startAccessPoint(conn, connPath, devPath); err != nil {
+			log.Fatal(err)
+		}
+		os.Exit(0)
+
+	case "down":
+		if err := stopAccessPoint(conn, devPath); err != nil {
+			log.Fatal(err)
+		}
+		os.Exit(0)
+
+	case "remove":
+		if connPath == "" {
+			fmt.Println("No connection found to remove")
+			os.Exit(0)
+		}
+		if err := removeConnection(conn, connPath); err != nil {
+			log.Fatal(err)
+		}
+		os.Exit(0)
+
+	default:
+		usage()
+	}
+}