fix(teardown): properly destroy a topology when initial connect fails

Fixes NODE-1595

lib/mongo_client.js

@@ -201,8 +201,9 @@ MongoClient.prototype.close = function(force, callback) {
  if (typeof force === 'function') (callback = force), (force = false);
 
  // Close the topology connection
- this.topology.close(force);
-
+ if (this.topology) {
+ this.topology.close(force);
+ }
  // Emit close event
  this.emit('close', this);
 

lib/operations/mongo_client_ops.js

@@ -334,16 +334,21 @@ function createServer(mongoClient, options, callback) {
  // Propagate the events to the client
  const collectedEvents = collectEvents(mongoClient, servers[0]);
 
+ const server = servers[0];
+
  // Connect to topology
- servers[0].connect(options, (err, topology) => {
- if (err) return callback(err);
+ server.connect(options, (err, topology) => {
+ if (err) {
+ server.close(true);
+ return callback(err);
+ }
  // Clear out all the collected event listeners
- clearAllEvents(servers[0]);
+ clearAllEvents(server);
 
  // Relay all the events
- relayEvents(mongoClient, servers[0]);
+ relayEvents(mongoClient, server);
  // Add listeners
- addListeners(mongoClient, servers[0]);
+ addListeners(mongoClient, server);
  // Check if we are really speaking to a mongos
  const ismaster = topology.lastIsMaster();
 
@@ -388,7 +393,10 @@ function createTopology(mongoClient, topologyType, options, callback) {
 
  // Open the connection
  topology.connect(options, (err, topology) => {
- if (err) return callback(err);
+ if (err) {
+ topology.close(true);
+ return callback(err);
+ }
 
  assignTopology(mongoClient, topology);
  callback(null, topology);