Move all of tun into overlay (#577)

overlay/tun.go

@@ -0,0 +1,41 @@
+package overlay
+
+import (
+	"net"
+
+	"github.com/sirupsen/logrus"
+	"github.com/slackhq/nebula/config"
+)
+
+const DefaultMTU = 1300
+
+func NewDeviceFromConfig(c *config.C, l *logrus.Logger, tunCidr *net.IPNet, routes, unsafeRoutes []Route, fd *int, routines int) (Device, error) {
+	switch {
+	case c.GetBool("tun.disabled", false):
+		tun := newDisabledTun(tunCidr, c.GetInt("tun.tx_queue", 500), c.GetBool("stats.message_metrics", false), l)
+		return tun, nil
+
+	case fd != nil:
+		return newTunFromFd(
+			l,
+			*fd,
+			tunCidr,
+			c.GetInt("tun.mtu", DefaultMTU),
+			routes,
+			unsafeRoutes,
+			c.GetInt("tun.tx_queue", 500),
+		)
+
+	default:
+		return newTun(
+			l,
+			c.GetString("tun.dev", ""),
+			tunCidr,
+			c.GetInt("tun.mtu", DefaultMTU),
+			routes,
+			unsafeRoutes,
+			c.GetInt("tun.tx_queue", 500),
+			routines > 1,
+		)
+	}
+}