TUN Interface Management

This module provides functionality to manage TUN (network tunnel) interfaces on Linux and macOS systems.

Functions

available() !bool

Checks if TUN/TAP functionality is available on the system:- Linux: Verifies /dev/net/tun exists and is a character device

• macOS: Checks for utun interfaces using ifconfig and sysctl

free() !string

Returns the name of an available TUN interface:- Linux: Returns first available interface from tun0-tun10

• macOS: Returns next available utun interface number

Example Usage

//#!/usr/bin/env -S v -n -w -gc none  -cc tcc -d use_openssl -enable-globals run
import freeflowuniverse.herolib.osal.tun


// Check if TUN is available
if available := tun.available() {
    if available {
        println('TUN is available on this system')

        // Get a free TUN interface name
        if interface_name := tun.free() {
            println('Found free TUN interface: ${interface_name}')

            // Example: Now you could use this interface name
            // to set up your tunnel
        } else {
            println('Error finding free interface: ${err}')
        }
    } else {
        println('TUN is not available on this system')
    }
} else {
    println('Error checking TUN availability: ${err}')
}

Platform Support

The module automatically detects the platform (Linux/macOS) and uses the appropriate methods:

• On Linux: Uses /dev/net/tun and ip link commands
• On macOS: Uses utun interfaces via ifconfig

Error Handling

Both functions return a Result type, so errors should be handled appropriately:- Unsupported platform errors

• Interface availability errors
• System command execution errors

fn available() !bool

available checks if TUN/TAP is available on the system

fn free() !string

free returns the name of an available TUN interface e.g. returns 'utun1'