//go:build linux

package netdetect

import (
	"os"
	"os/exec"
)

// DefaultRoutes returns the host's IPv4 default routes. It prefers the `ip`
// command and falls back to reading /proc/net/route.
func DefaultRoutes() ([]Route, error) {
	out, err := exec.Command("ip", "-4", "route", "show", "default").Output()
	if err == nil {
		if routes := parseIPRoute(string(out)); len(routes) > 0 {
			return routes, nil
		}
	}

	data, err := os.ReadFile("/proc/net/route")
	if err != nil {
		return nil, err
	}

	return parseProcNetRoute(string(data)), nil
}