Simplify QUIC stateless rejects by latching the value of FLAGS_enable_quic_stateless_reject_support…

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"
@@ skipping 20 matching lines @@
 
 QuicCryptoServerStream::QuicCryptoServerStream(
     const QuicCryptoServerConfig* crypto_config,
     QuicSession* session)
     : QuicCryptoStream(session),
       crypto_config_(crypto_config),
       validate_client_hello_cb_(nullptr),
       num_handshake_messages_(0),
       num_handshake_messages_with_server_nonces_(0),
       num_server_config_update_messages_sent_(0),
-      use_stateless_rejects_if_peer_supported_(false),
+      use_stateless_rejects_if_peer_supported_(
+          FLAGS_enable_quic_stateless_reject_support),
       peer_supports_stateless_rejects_(false) {
   DCHECK_EQ(Perspective::IS_SERVER, session->connection()->perspective());
 }
 
 QuicCryptoServerStream::~QuicCryptoServerStream() {
   CancelOutstandingCallbacks();
 }
 
 void QuicCryptoServerStream::CancelOutstandingCallbacks() {
   // Detach from the validation callback.  Calling this multiple times is safe.
@@ skipping 34 matching lines @@
       validate_client_hello_cb_);
 }
 
 void QuicCryptoServerStream::FinishProcessingHandshakeMessage(
     const CryptoHandshakeMessage& message,
     const ValidateClientHelloResultCallback::Result& result) {
   // Clear the callback that got us here.
   DCHECK(validate_client_hello_cb_ != nullptr);
   validate_client_hello_cb_ = nullptr;
 
-  if (FLAGS_enable_quic_stateless_reject_support) {
+  if (use_stateless_rejects_if_peer_supported_) {
     peer_supports_stateless_rejects_ = DoesPeerSupportStatelessRejects(message);
   }
 
   CryptoHandshakeMessage reply;
   string error_details;
   QuicErrorCode error =
       ProcessClientHello(message, result, &reply, &error_details);
 
   if (error != QUIC_NO_ERROR) {
     CloseConnectionWithDetails(error, error_details);
     return;
   }
 
   if (reply.tag() != kSHLO) {
-    if (FLAGS_enable_quic_stateless_reject_support &&
-        reply.tag() == kSREJ) {
+    if (reply.tag() == kSREJ) {
+      DCHECK(use_stateless_rejects_if_peer_supported());
+      DCHECK(peer_supports_stateless_rejects());
       // Before sending the SREJ, cause the connection to save crypto packets
       // so that they can be added to the time wait list manager and
       // retransmitted.
       session()->connection()->EnableSavingCryptoPackets();
     }
     SendHandshakeMessage(reply);
 
-    if (FLAGS_enable_quic_stateless_reject_support && reply.tag() == kSREJ) {
+    if (reply.tag() == kSREJ) {
       DCHECK(use_stateless_rejects_if_peer_supported());
       DCHECK(peer_supports_stateless_rejects());
       DCHECK(!handshake_confirmed());
       DVLOG(1) << "Closing connection "
                << session()->connection()->connection_id()
                << " because of a stateless reject.";
       session()->connection()->CloseConnection(
           QUIC_CRYPTO_HANDSHAKE_STATELESS_REJECT, /* from_peer */ false);
     }
     return;
@@ skipping 124 matching lines @@
     ++num_handshake_messages_with_server_nonces_;
   }
   // Store the bandwidth estimate from the client.
   if (result.cached_network_params.bandwidth_estimate_bytes_per_second() > 0) {
     previous_cached_network_params_.reset(
         new CachedNetworkParameters(result.cached_network_params));
   }
   previous_source_address_tokens_ = result.info.source_address_tokens;
 
   const bool use_stateless_rejects_in_crypto_config =
-      FLAGS_enable_quic_stateless_reject_support &&
       use_stateless_rejects_if_peer_supported_ &&
       peer_supports_stateless_rejects_;
   QuicConnection* connection = session()->connection();
   const QuicConnectionId server_designated_connection_id =
       use_stateless_rejects_in_crypto_config
           ? GenerateConnectionIdForReject(connection->connection_id())
           : 0;
   return crypto_config_->ProcessClientHello(
       result, connection->connection_id(), connection->self_address().address(),
       connection->peer_address(), version(), connection->supported_versions(),
@@ skipping 43 matching lines @@
   }
   for (size_t i = 0; i < received_tags_length; ++i) {
     if (received_tags[i] == kSREJ) {
       return true;
     }
   }
   return false;
 }
 
 }  // namespace net