Update

vendor/tailscale.com/net/dnsfallback/dnsfallback.go

@@ -1,4 +1,4 @@
-// Copyright (c) Tailscale Inc & AUTHORS
+// Copyright (c) Tailscale Inc & contributors
 // SPDX-License-Identifier: BSD-3-Clause
 
 // Package dnsfallback contains a DNS fallback mechanism
@@ -30,6 +30,7 @@ import (
 	"tailscale.com/health"
 	"tailscale.com/net/netmon"
 	"tailscale.com/net/netns"
+	"tailscale.com/net/netutil"
 	"tailscale.com/net/tlsdial"
 	"tailscale.com/tailcfg"
 	"tailscale.com/types/logger"
@@ -130,10 +131,14 @@ func lookup(ctx context.Context, host string, logf logger.Logf, ht *health.Track
 // serverName and serverIP of are, say, "derpN.tailscale.com".
 // queryName is the name being sought (e.g. "controlplane.tailscale.com"), passed as hint.
 //
-// ht may be nil.
+// ht and netMon may be nil. If netMon is nil, a plain net.Dialer is used
+// instead of a netns-aware one.
 func bootstrapDNSMap(ctx context.Context, serverName string, serverIP netip.Addr, queryName string, logf logger.Logf, ht *health.Tracker, netMon *netmon.Monitor) (dnsMap, error) {
-	dialer := netns.NewDialer(logf, netMon)
-	tr := http.DefaultTransport.(*http.Transport).Clone()
+	var dialer netns.Dialer = new(net.Dialer)
+	if netMon != nil {
+		dialer = netns.NewDialer(logf, netMon)
+	}
+	tr := netutil.NewDefaultTransport()
 	tr.DisableKeepAlives = true // This transport is meant to be used once.
 	tr.Proxy = feature.HookProxyFromEnvironment.GetOrNil()
 	tr.DialContext = func(ctx context.Context, netw, addr string) (net.Conn, error) {