Fix nil pointer deref on uncommon tor errors

tor/torProvider.go

@@ -192,17 +192,22 @@ func (tp *torProvider) Listen(identity connectivity.PrivateKey, port int) (conne
 
 	conf := &tor.ListenConf{NoWait: true, Version3: true, Key: identity, RemotePorts: []int{port}, Detach: true, DiscardKey: true, LocalListener: localListener}
 	os, err := tp.t.Listen(nil, conf)
+
+	// Reattach to the old local listener...
+	// Note: this code probably shouldn't be hit in Cwtch anymore because we purge torrc on restart.
 	if err != nil && strings.Contains(err.Error(), "550 Unspecified Tor error: Onion address collision") {
+		log.Errorf("550 Unspecified Tor error: Onion address collision - Recovering, but this probably indicates some weird tor configuration issue...")
 		os = &tor.OnionService{Tor: tp.t, LocalListener: localListener, ID: onion, Version3: true, Key: bineed255192.FromCryptoPrivateKey(privkey), ClientAuths: make(map[string]string, 0), RemotePorts: []int{port}}
 		err = nil
 	}
-	// Not set in t.Listen if supplied, we want it to handle this however
-	os.CloseLocalListenerOnClose = true
 
+	// Any other errors require an immediate return as os is likely nil...
 	if err != nil {
 		return nil, err
 	}
 
+	os.CloseLocalListenerOnClose = true
+
 	ols := &onionListenService{os: os, tp: tp}
 	tp.childListeners[ols.AddressIdentity()] = ols
 	return ols, nil
@@ -218,7 +223,6 @@ func (tp *torProvider) Restart() {
 		return
 	}
 
-
 	go tp.restart()
 }
 

tor/torProvider_test.go

@@ -45,7 +45,5 @@ func TestTorProvider(t *testing.T) {
 	acn.Restart()
 	acn.Restart()
 
-
-
 	acn.Close()
 }