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//go:build linux
package netstate
import (
"bufio"
"net"
"os"
"slices"
"strconv"
"strings"
"github.com/armanlife/firefox-vpn-client/core/internal/egress"
)
// connected looks for a default route (IPv4 or IPv6) on an interface
// other than loopback and the TUN mode's adapter.
func connected() bool {
tun := tunName()
v4, err4 := hasDefaultRoute("/proc/net/route", parseRoute4, tun)
v6, err6 := hasDefaultRoute("/proc/net/ipv6_route", parseRoute6, tun)
if err4 != nil && err6 != nil {
return true
}
return v4 || v6
}
// current names the connected networks: the default routes, with their
// interfaces and gateways.
func current() (string, bool) {
tun := tunName()
v4, err4 := defaultRoutes("/proc/net/route", parseRoute4, tun, 0, 2)
v6, err6 := defaultRoutes("/proc/net/ipv6_route", parseRoute6, tun, 9, 4)
if err4 != nil && err6 != nil {
return "", false
}
return strings.Join(append(v4, v6...), ";"), true
}
// tunName is the TUN mode's adapter while one runs: it has default routes
// (IPv6's are listed with the system's) but is no network of its own.
func tunName() string {
index, _, ok := egress.Tun()
if !ok {
return ""
}
iface, err := net.InterfaceByIndex(int(index))
if err != nil {
return ""
}
return iface.Name
}
// defaultRoutes lists "interface gateway" for each default route in path.
func defaultRoutes(path string, isDefault func([]string, string) bool, tun string, iface, gateway int) ([]string, error) {
f, err := os.Open(path)
if err != nil {
return nil, err
}
defer f.Close()
var routes []string
scanner := bufio.NewScanner(f)
for scanner.Scan() {
if fields := strings.Fields(scanner.Text()); isDefault(fields, tun) {
routes = append(routes, fields[iface]+" "+fields[gateway])
}
}
slices.Sort(routes)
return routes, scanner.Err()
}
const routeUp = 0x1 // RTF_UP
func hasDefaultRoute(path string, isDefault func([]string, string) bool, tun string) (bool, error) {
f, err := os.Open(path)
if err != nil {
return false, err
}
defer f.Close()
scanner := bufio.NewScanner(f)
for scanner.Scan() {
if isDefault(strings.Fields(scanner.Text()), tun) {
return true, nil
}
}
return false, scanner.Err()
}
// parseRoute4 reads a /proc/net/route line: Iface Destination Gateway
// Flags RefCnt Use Metric Mask ...
func parseRoute4(f []string, tun string) bool {
if len(f) < 8 || f[0] == "lo" || (tun != "" && f[0] == tun) || f[1] != "00000000" || f[7] != "00000000" {
return false
}
flags, err := strconv.ParseUint(f[3], 16, 32)
return err == nil && flags&routeUp != 0
}
// parseRoute6 reads a /proc/net/ipv6_route line: Destination PrefixLen
// Source SourcePrefixLen NextHop Metric RefCnt Use Flags Iface. Loopback
// carries unreachable default entries, which do not count.
func parseRoute6(f []string, tun string) bool {
if len(f) < 10 || f[9] == "lo" || (tun != "" && f[9] == tun) || f[0] != strings.Repeat("0", 32) || f[1] != "00" {
return false
}
flags, err := strconv.ParseUint(f[8], 16, 32)
return err == nil && flags&routeUp != 0
}
arblant