chore(all): make code compilable for other platforms than Linux

internal/netlink/wireguard_linux.go

@@ -0,0 +1,35 @@
+package netlink
+
+import (
+	"github.com/qdm12/gluetun/internal/mod"
+	"github.com/vishvananda/netlink"
+)
+
+func (n *NetLink) IsWireguardSupported() bool {
+	// Check for Wireguard family without loading the wireguard module.
+	// Some kernels have the wireguard module built-in, and don't have a
+	// modules directory, such as WSL2 kernels.
+	ok := hasWireguardFamily()
+	if ok {
+		return true
+	}
+
+	// Try loading the wireguard module, since some systems do not load
+	// it after a boot. If this fails, wireguard is assumed to not be supported.
+	n.debugLogger.Debugf("wireguard family not found, trying to load wireguard kernel module")
+	err := mod.Probe("wireguard")
+	if err != nil {
+		n.debugLogger.Debugf("failed loading wireguard kernel module: %s", err)
+		return false
+	}
+	n.debugLogger.Debugf("wireguard kernel module loaded successfully")
+
+	// Re-check if the Wireguard family is now available, after loading
+	// the wireguard kernel module.
+	return hasWireguardFamily()
+}
+
+func hasWireguardFamily() bool {
+	_, err := netlink.GenlFamilyGet("wireguard")
+	return err == nil
+}