From 2f8719741e6de14539e31173f1acd9efae0b8a2e Mon Sep 17 00:00:00 2001
From: David Crawshaw <crawshaw@tailscale.com>
Date: Thu, 2 Apr 2020 11:18:39 +1100
Subject: [PATCH] controlclient: do not send duplicate hostinfo/netinfo

This should never happen, so log when it does so we can fix it.

Signed-off-by: David Crawshaw <crawshaw@tailscale.com>
---
 control/controlclient/auto.go   | 14 ++++++++++++--
 control/controlclient/direct.go | 21 ++++++++++++++-------
 2 files changed, 26 insertions(+), 9 deletions(-)

diff --git a/control/controlclient/auto.go b/control/controlclient/auto.go
index ce49ad0ec..831b736cb 100644
--- a/control/controlclient/auto.go
+++ b/control/controlclient/auto.go
@@ -496,7 +496,12 @@ func (c *Client) SetHostinfo(hi *tailcfg.Hostinfo) {
 	if hi == nil {
 		panic("nil Hostinfo")
 	}
-	c.direct.SetHostinfo(hi)
+	if !c.direct.SetHostinfo(hi) {
+		c.logf("[unexpected] duplicate Hostinfo: %v", hi)
+		return
+	}
+	c.logf("Hostinfo: %v", hi)
+
 	// Send new Hostinfo to server
 	c.cancelMapSafely()
 }
@@ -505,7 +510,12 @@ func (c *Client) SetNetInfo(ni *tailcfg.NetInfo) {
 	if ni == nil {
 		panic("nil NetInfo")
 	}
-	c.direct.SetNetInfo(ni)
+	if !c.direct.SetNetInfo(ni) {
+		c.logf("[unexpected] duplicate NetInfo: %v", ni)
+		return
+	}
+	c.logf("NetInfo: %v", ni)
+
 	// Send new Hostinfo (which includes NetInfo) to server
 	c.cancelMapSafely()
 }
diff --git a/control/controlclient/direct.go b/control/controlclient/direct.go
index a8c8b460f..56a8f30c0 100644
--- a/control/controlclient/direct.go
+++ b/control/controlclient/direct.go
@@ -17,6 +17,7 @@ import (
 	"log"
 	"net/http"
 	"os"
+	"reflect"
 	"strconv"
 	"strings"
 	"sync"
@@ -149,21 +150,24 @@ func NewHostinfo() *tailcfg.Hostinfo {
 }
 
 // SetHostinfo clones the provided Hostinfo and remembers it for the
-// next update.
-func (c *Direct) SetHostinfo(hi *tailcfg.Hostinfo) {
+// next update. It reports whether the Hostinfo has changed.
+func (c *Direct) SetHostinfo(hi *tailcfg.Hostinfo) bool {
 	if hi == nil {
 		panic("nil Hostinfo")
 	}
 	c.mu.Lock()
 	defer c.mu.Unlock()
 
-	c.logf("Hostinfo: %v\n", hi)
+	if hi.Equal(c.hostinfo) {
+		return false
+	}
 	c.hostinfo = hi.Clone()
+	return true
 }
 
 // SetNetInfo clones the provided NetInfo and remembers it for the
-// next update.
-func (c *Direct) SetNetInfo(ni *tailcfg.NetInfo) {
+// next update. It reports whether the NetInfo has changed.
+func (c *Direct) SetNetInfo(ni *tailcfg.NetInfo) bool {
 	if ni == nil {
 		panic("nil NetInfo")
 	}
@@ -172,10 +176,13 @@ func (c *Direct) SetNetInfo(ni *tailcfg.NetInfo) {
 
 	if c.hostinfo == nil {
 		c.logf("[unexpected] SetNetInfo called with no HostInfo; ignoring NetInfo update: %+v", ni)
-		return
+		return false
+	}
+	if reflect.DeepEqual(ni, c.hostinfo.NetInfo) {
+		return false
 	}
-	c.logf("NetInfo: %v\n", ni)
 	c.hostinfo.NetInfo = ni.Clone()
+	return true
 }
 
 func (c *Direct) GetPersist() Persist {