add go-tun2socks code

common/route/route_linux.go

@@ -0,0 +1,18 @@
+package route
+
+import (
+	"errors"
+	"fmt"
+	"os/exec"
+)
+
+func AddRoute(dest, netmask, gateway string) error {
+	out, err := exec.Command("ip", "route", "add", dest+"/32", "via", gateway).Output()
+	if err != nil {
+		if len(out) != 0 {
+			return errors.New(fmt.Sprintf("%v, output: %s", err, out))
+		}
+		return err
+	}
+	return nil
+}