[Draft] Fix canceling pin prompt causes host overload

remoting/host/chromoting_host.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "remoting/host/chromoting_host.h"
 
 #include <algorithm>
 
 #include "base/bind.h"
 #include "base/callback.h"
@@ skipping 153 matching lines @@
     DisconnectAllClients();
 }
 
 void ChromotingHost::SetMaximumSessionDuration(
     const base::TimeDelta& max_session_duration) {
   max_session_duration_ = max_session_duration;
 }
 
 ////////////////////////////////////////////////////////////////////////////
 // protocol::ClientSession::EventHandler implementation.
+void ChromotingHost::OnSessionAuthenticating(ClientSession* client) {
+  // We treat each incoming connection as a failure to authenticate,
+  // and clear the backoff when a connection successfully
+  // authenticates. This allows the backoff to protect from parallel
+  // connection attempts as well as sequential ones.
+  if (login_backoff_.ShouldRejectRequest()) {
+    LOG(WARNING) << "Disconnecting client " << client->client_jid() << " due to"
+                    " an overload of failed login attempts.";
+    client->DisconnectSession();
+    return;
+  }
+  login_backoff_.InformOfRequest(false);
+}
+
 bool ChromotingHost::OnSessionAuthenticated(ClientSession* client) {
   DCHECK(CalledOnValidThread());
 
   login_backoff_.Reset();
 
   // Disconnect all other clients. |it| should be advanced before Disconnect()
   // is called to avoid it becoming invalid when the client is removed from
   // the list.
   ClientList::iterator it = clients_.begin();
   while (it != clients_.end()) {
@@ skipping 74 matching lines @@
       protocol::Session* session,
       protocol::SessionManager::IncomingSessionResponse* response) {
   DCHECK(CalledOnValidThread());
 
   if (!started_) {
     *response = protocol::SessionManager::DECLINE;
     return;
   }
 
   if (login_backoff_.ShouldRejectRequest()) {
+    LOG(WARNING) << "Rejecting connection due to"
+                    " an overload of failed login attempts.";
     *response = protocol::SessionManager::OVERLOAD;
     return;
   }
 
-  // We treat each incoming connection as a failure to authenticate,
-  // and clear the backoff when a connection successfully
-  // authenticates. This allows the backoff to protect from parallel
-  // connection attempts as well as sequential ones.
-  login_backoff_.InformOfRequest(false);
-
   protocol::SessionConfig config;
   if (!protocol_config_->Select(session->candidate_config(), &config)) {
     LOG(WARNING) << "Rejecting connection from " << session->jid()
                  << " because no compatible configuration has been found.";
     *response = protocol::SessionManager::INCOMPATIBLE;
     return;
   }
 
   session->set_config(config);
 
@@ skipping 31 matching lines @@
   DCHECK(CalledOnValidThread());
 
   while (!clients_.empty()) {
     size_t size = clients_.size();
     clients_.front()->DisconnectSession();
     CHECK_EQ(clients_.size(), size - 1);
   }
 }
 
 }  // namespace remoting