Avoid race by using conditional deep copy

Signed-off-by: Derek Collison <derek@nats.io>

server/client.go

@@ -908,7 +908,7 @@ func (c *client) processPing() {
 		// If there was a cluster update since this client was created,
 		// send an updated INFO protocol now.
 		if srv.lastCURLsUpdate >= c.start.UnixNano() {
-			c.sendInfo(c.generateClientInfoJSON(srv.info))
+			c.sendInfo(c.generateClientInfoJSON(srv.copyInfo()))
 		}
 		c.mu.Unlock()
 		srv.mu.Unlock()

server/route.go

@@ -389,7 +389,7 @@ func (s *Server) sendAsyncInfoToClients() {
 		if c.opts.Protocol >= ClientProtoInfo && c.flags.isSet(firstPongSent) {
 			// sendInfo takes care of checking if the connection is still
 			// valid or not, so don't duplicate tests here.
-			c.sendInfo(c.generateClientInfoJSON(s.info))
+			c.sendInfo(c.generateClientInfoJSON(s.copyInfo()))
 		}
 		c.mu.Unlock()
 	}

server/server.go

@@ -708,6 +708,18 @@ func (s *Server) HTTPHandler() http.Handler {
 	return s.httpHandler
 }
 
+// Perform a conditional deep copy due to reference nature of ClientConnectURLs.
+// If updates are made to Info, this function should be consulted and updated.
+// Assume lock is held.
+func (s *Server) copyInfo() Info {
+	info := s.info
+	if info.ClientConnectURLs != nil {
+		info.ClientConnectURLs = make([]string, len(s.info.ClientConnectURLs))
+		copy(info.ClientConnectURLs, s.info.ClientConnectURLs)
+	}
+	return info
+}
+
 func (s *Server) createClient(conn net.Conn) *client {
 	// Snapshot server options.
 	opts := s.getOpts()
@@ -716,7 +728,7 @@ func (s *Server) createClient(conn net.Conn) *client {
 
 	// Grab JSON info string
 	s.mu.Lock()
-	info := s.info
+	info := s.copyInfo()
 	s.totalClients++
 	s.mu.Unlock()