Delay a QUIC server's use of the FORWARD_SECURE encrypter until the

net/quic/quic_crypto_server_stream.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 "net/quic/quic_crypto_server_stream.h"
 
 #include "base/base64.h"
 #include "crypto/secure_hash.h"
 #include "net/quic/crypto/crypto_protocol.h"
 #include "net/quic/crypto/crypto_utils.h"
 #include "net/quic/crypto/quic_crypto_server_config.h"
 #include "net/quic/crypto/source_address_token.h"
 #include "net/quic/quic_config.h"
+#include "net/quic/quic_flags.h"
 #include "net/quic/quic_protocol.h"
 #include "net/quic/quic_session.h"
 
 namespace net {
 
 void ServerHelloNotifier::OnAckNotification(
     int num_original_packets,
     int num_original_bytes,
     int num_retransmitted_packets,
     int num_retransmitted_bytes,
@@ skipping 88 matching lines @@
   config->ToHandshakeMessage(&reply);
 
   // Receiving a full CHLO implies the client is prepared to decrypt with
   // the new server write key.  We can start to encrypt with the new server
   // write key.
   //
   // NOTE: the SHLO will be encrypted with the new server write key.
   session()->connection()->SetEncrypter(
       ENCRYPTION_INITIAL,
       crypto_negotiated_params_.initial_crypters.encrypter.release());
-  session()->connection()->SetDefaultEncryptionLevel(
-      ENCRYPTION_INITIAL);
+  session()->connection()->SetDefaultEncryptionLevel(ENCRYPTION_INITIAL);
   // Set the decrypter immediately so that we no longer accept unencrypted
   // packets.
   session()->connection()->SetDecrypter(
       crypto_negotiated_params_.initial_crypters.decrypter.release(),
       ENCRYPTION_INITIAL);
 
   // We want to be notified when the SHLO is ACKed so that we can disable
   // HANDSHAKE_MODE in the sent packet manager.
   if (session()->connection()->version() <= QUIC_VERSION_21) {
     SendHandshakeMessage(reply);
   } else {
     scoped_refptr<ServerHelloNotifier> server_hello_notifier(
         new ServerHelloNotifier(this));
     SendHandshakeMessage(reply, server_hello_notifier.get());
   }
 
   session()->connection()->SetEncrypter(
       ENCRYPTION_FORWARD_SECURE,
       crypto_negotiated_params_.forward_secure_crypters.encrypter.release());
-  session()->connection()->SetDefaultEncryptionLevel(
-      ENCRYPTION_FORWARD_SECURE);
+  if (!FLAGS_enable_quic_delay_forward_security) {
+    session()->connection()->SetDefaultEncryptionLevel(
+        ENCRYPTION_FORWARD_SECURE);
+  }
   session()->connection()->SetAlternativeDecrypter(
       crypto_negotiated_params_.forward_secure_crypters.decrypter.release(),
       ENCRYPTION_FORWARD_SECURE, false /* don't latch */);
 
   encryption_established_ = true;
   handshake_confirmed_ = true;
   session()->OnCryptoHandshakeEvent(QuicSession::HANDSHAKE_CONFIRMED);
 }
 
 void QuicCryptoServerStream::SendServerConfigUpdate(
@@ skipping 101 matching lines @@
 
 void QuicCryptoServerStream::ValidateCallback::RunImpl(
     const CryptoHandshakeMessage& client_hello,
     const Result& result) {
   if (parent_ != nullptr) {
     parent_->FinishProcessingHandshakeMessage(client_hello, result);
   }
 }
 
 }  // namespace net