ipn, etc: use controlplane.tailscale.com

Signed-off-by: David Crawshaw <crawshaw@tailscale.com>

net/dnsfallback/dnsfallback.go

@@ -87,7 +87,7 @@ func Lookup(ctx context.Context, host string) ([]netaddr.IP, error) {
 }
 
 // serverName and serverIP of are, say, "derpN.tailscale.com".
-// queryName is the name being sought (e.g. "login.tailscale.com"), passed as hint.
+// queryName is the name being sought (e.g. "controlplane.tailscale.com"), passed as hint.
 func bootstrapDNSMap(ctx context.Context, serverName string, serverIP netaddr.IP, queryName string) (dnsMap, error) {
 	dialer := netns.NewDialer()
 	tr := http.DefaultTransport.(*http.Transport).Clone()

net/interfaces/interfaces.go

@@ -22,7 +22,7 @@ import (
 
 // LoginEndpointForProxyDetermination is the URL used for testing
 // which HTTP proxy the system should use.
-var LoginEndpointForProxyDetermination = "https://login.tailscale.com/"
+var LoginEndpointForProxyDetermination = "https://controlplane.tailscale.com/"
 
 // Tailscale returns the current machine's Tailscale interface, if any.
 // If none is found, all zero values are returned.