From 97e82c6cc00a55148227c2d4443f4e86c02ef013 Mon Sep 17 00:00:00 2001
From: Brad Fitzpatrick <bradfitz@tailscale.com>
Date: Wed, 11 Nov 2020 11:52:35 -0800
Subject: [PATCH] net/netcheck: remove unused DNSCache from netcheck

It's easy to add back later if/when the TODO is implemented.
---
 cmd/tailscale/cli/netcheck.go | 5 +----
 net/netcheck/netcheck.go      | 5 -----
 2 files changed, 1 insertion(+), 9 deletions(-)

diff --git a/cmd/tailscale/cli/netcheck.go b/cmd/tailscale/cli/netcheck.go
index 1ad30dd02..04d3ab0ab 100644
--- a/cmd/tailscale/cli/netcheck.go
+++ b/cmd/tailscale/cli/netcheck.go
@@ -17,7 +17,6 @@ import (
 
 	"github.com/peterbourgon/ff/v2/ffcli"
 	"tailscale.com/derp/derpmap"
-	"tailscale.com/net/dnscache"
 	"tailscale.com/net/netcheck"
 	"tailscale.com/tailcfg"
 	"tailscale.com/types/logger"
@@ -44,9 +43,7 @@ var netcheckArgs struct {
 }
 
 func runNetcheck(ctx context.Context, args []string) error {
-	c := &netcheck.Client{
-		DNSCache: dnscache.Get(),
-	}
+	c := &netcheck.Client{}
 	if netcheckArgs.verbose {
 		c.Logf = logger.WithPrefix(log.Printf, "netcheck: ")
 		c.Verbose = true
diff --git a/net/netcheck/netcheck.go b/net/netcheck/netcheck.go
index 272f2333d..cdb767bff 100644
--- a/net/netcheck/netcheck.go
+++ b/net/netcheck/netcheck.go
@@ -28,7 +28,6 @@ import (
 	"go4.org/mem"
 	"inet.af/netaddr"
 	"tailscale.com/derp/derphttp"
-	"tailscale.com/net/dnscache"
 	"tailscale.com/net/interfaces"
 	"tailscale.com/net/netns"
 	"tailscale.com/net/stun"
@@ -134,10 +133,6 @@ func cloneDurationMap(m map[int]time.Duration) map[int]time.Duration {
 
 // Client generates a netcheck Report.
 type Client struct {
-	// DNSCache optionally specifies a DNSCache to use.
-	// If nil, a DNS cache is not used.
-	DNSCache *dnscache.Resolver
-
 	// Verbose enables verbose logging.
 	Verbose bool