From a8305210786cce91bfca5b61214f5b6a173c620c Mon Sep 17 00:00:00 2001
From: Neil Alexander <neilalexander@users.noreply.github.com>
Date: Fri, 29 Mar 2019 08:38:09 +0000
Subject: [PATCH] Don't crash if Yggdrasil is started with no router adapter

---
 cmd/yggdrasil/main.go   |  6 +++---
 src/yggdrasil/core.go   | 12 ++++++++----
 src/yggdrasil/router.go |  4 +++-
 3 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/cmd/yggdrasil/main.go b/cmd/yggdrasil/main.go
index 72f02840..9278867b 100644
--- a/cmd/yggdrasil/main.go
+++ b/cmd/yggdrasil/main.go
@@ -248,10 +248,10 @@ func main() {
 	// Setup the Yggdrasil node itself. The node{} type includes a Core, so we
 	// don't need to create this manually.
 	n := node{}
-	// Now that we have a working configuration, we can now actually start
-	// Yggdrasil. This will start the router, switch, DHT node, TCP and UDP
-	// sockets, TUN/TAP adapter and multicast discovery port.
+	// Before we start the node, set the TUN/TAP to be our router adapter
 	n.core.SetRouterAdapter(&n.tuntap)
+	// Now start Yggdrasil - this starts the DHT, router, switch and other core
+	// components needed for Yggdrasil to operate
 	state, err := n.core.Start(cfg, logger)
 	if err != nil {
 		logger.Errorln("An error occurred during startup")
diff --git a/src/yggdrasil/core.go b/src/yggdrasil/core.go
index dbc893a8..0e9b251e 100644
--- a/src/yggdrasil/core.go
+++ b/src/yggdrasil/core.go
@@ -220,9 +220,11 @@ func (c *Core) Start(nc *config.NodeConfig, log *log.Logger) (*config.NodeState,
 		return nil, err
 	}
 
-	if err := c.router.adapter.Start(c.router.addr, c.router.subnet); err != nil {
-		c.log.Errorln("Failed to start TUN/TAP")
-		return nil, err
+	if c.router.adapter != nil {
+		if err := c.router.adapter.Start(c.router.addr, c.router.subnet); err != nil {
+			c.log.Errorln("Failed to start TUN/TAP")
+			return nil, err
+		}
 	}
 
 	go c.addPeerLoop()
@@ -234,7 +236,9 @@ func (c *Core) Start(nc *config.NodeConfig, log *log.Logger) (*config.NodeState,
 // Stops the Yggdrasil node.
 func (c *Core) Stop() {
 	c.log.Infoln("Stopping...")
-	c.router.adapter.Close()
+	if c.router.adapter != nil {
+		c.router.adapter.Close()
+	}
 	c.admin.close()
 }
 
diff --git a/src/yggdrasil/router.go b/src/yggdrasil/router.go
index 6314cb12..bef564fd 100644
--- a/src/yggdrasil/router.go
+++ b/src/yggdrasil/router.go
@@ -128,7 +128,9 @@ func (r *router) init(core *Core) {
 	r.nodeinfo.setNodeInfo(r.core.config.Current.NodeInfo, r.core.config.Current.NodeInfoPrivacy)
 	r.core.config.Mutex.RUnlock()
 	r.cryptokey.init(r.core)
-	r.adapter.Init(&r.core.config, r.core.log, send, recv, reject)
+	if r.adapter != nil {
+		r.adapter.Init(&r.core.config, r.core.log, send, recv, reject)
+	}
 }
 
 // Starts the mainLoop goroutine.