From e298327ba8d7027808a202538b3f9529842cd196 Mon Sep 17 00:00:00 2001
From: Brad Fitzpatrick <bradfitz@tailscale.com>
Date: Sat, 25 Jul 2020 19:37:08 -0700
Subject: [PATCH] wgengine/magicsock: remove overkill, slow reflect.DeepEqual
 of NetworkMap

No need to allocate or compare all the fields we don't care about.
---
 wgengine/magicsock/magicsock.go | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/wgengine/magicsock/magicsock.go b/wgengine/magicsock/magicsock.go
index c7902a35d..248c3f5e1 100644
--- a/wgengine/magicsock/magicsock.go
+++ b/wgengine/magicsock/magicsock.go
@@ -1847,8 +1847,20 @@ func (c *Conn) SetDERPMap(dm *tailcfg.DERPMap) {
 	go c.ReSTUN("derp-map-update")
 }
 
+func nodesEqual(x, y []*tailcfg.Node) bool {
+	if len(x) != len(y) {
+		return false
+	}
+	for i := range x {
+		if !x[i].Equal(y[i]) {
+			return false
+		}
+	}
+	return true
+}
+
 // SetNetworkMap is called when the control client gets a new network
-// map from the control server.
+// map from the control server. It must always be non-nil.
 //
 // It should not use the DERPMap field of NetworkMap; that's
 // conditionally sent to SetDERPMap instead.
@@ -1856,7 +1868,7 @@ func (c *Conn) SetNetworkMap(nm *controlclient.NetworkMap) {
 	c.mu.Lock()
 	defer c.mu.Unlock()
 
-	if reflect.DeepEqual(nm, c.netMap) {
+	if c.netMap != nil && nodesEqual(c.netMap.Peers, nm.Peers) {
 		return
 	}