Disable QUIC versions less than v32, protected by --FLAGS_quic_disable_pre_32.

net/quic/core/quic_protocol.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/core/quic_protocol.h"
 
 #include "base/stl_util.h"
 #include "base/strings/string_number_conversions.h"
 #include "net/quic/core/quic_flags.h"
 #include "net/quic/core/quic_utils.h"
@@ skipping 169 matching lines @@
 }
 
 QuicVersionVector CurrentSupportedVersions() {
   return FilterSupportedVersions(AllSupportedVersions());
 }
 
 QuicVersionVector FilterSupportedVersions(QuicVersionVector versions) {
   QuicVersionVector filtered_versions(versions.size());
   filtered_versions.clear();  // Guaranteed by spec not to change capacity.
   for (QuicVersion version : versions) {
-    if (version == QUIC_VERSION_35) {
+    if (version < QUIC_VERSION_32) {
+      if (!FLAGS_quic_disable_pre_32) {
+        filtered_versions.push_back(version);
+      }
+    } else if (version == QUIC_VERSION_35) {
       if (FLAGS_quic_enable_version_35) {
         filtered_versions.push_back(version);
       }
     } else if (version == QUIC_VERSION_36) {
       if (FLAGS_quic_enable_version_35 && FLAGS_quic_enable_version_36_v2) {
         filtered_versions.push_back(version);
       }
     } else {
       filtered_versions.push_back(version);
     }
@@ skipping 641 matching lines @@
 
 StringPiece QuicPacket::Plaintext(QuicVersion version) const {
   const size_t start_of_encrypted_data = GetStartOfEncryptedData(
       version, connection_id_length_, includes_version_, includes_path_id_,
       includes_diversification_nonce_, packet_number_length_);
   return StringPiece(data() + start_of_encrypted_data,
                      length() - start_of_encrypted_data);
 }
 
 QuicVersionManager::QuicVersionManager(QuicVersionVector supported_versions)
-    : enable_quic_version_35_(FLAGS_quic_enable_version_35),
-      enable_quic_version_36_(FLAGS_quic_enable_version_36_v2),
+    : disable_pre_32_(FLAGS_quic_disable_pre_32),
+      enable_version_35_(FLAGS_quic_enable_version_35),
+      enable_version_36_(FLAGS_quic_enable_version_36_v2),
       allowed_supported_versions_(supported_versions),
       filtered_supported_versions_(
           FilterSupportedVersions(supported_versions)) {}
 
+QuicVersionManager::~QuicVersionManager() {}
+
 const QuicVersionVector& QuicVersionManager::GetSupportedVersions() {
-  if (enable_quic_version_35_ != FLAGS_quic_enable_version_35 ||
-      enable_quic_version_36_ != FLAGS_quic_enable_version_36_v2) {
-    enable_quic_version_35_ = FLAGS_quic_enable_version_35;
-    enable_quic_version_36_ = FLAGS_quic_enable_version_36_v2;
+  if (disable_pre_32_ != FLAGS_quic_disable_pre_32 ||
+      enable_version_35_ != FLAGS_quic_enable_version_35 ||
+      enable_version_36_ != FLAGS_quic_enable_version_36_v2) {
+    disable_pre_32_ = FLAGS_quic_disable_pre_32;
+    enable_version_35_ = FLAGS_quic_enable_version_35;
+    enable_version_36_ = FLAGS_quic_enable_version_36_v2;
     filtered_supported_versions_ =
         FilterSupportedVersions(allowed_supported_versions_);
   }
   return filtered_supported_versions_;
 }
 
-QuicVersionManager::~QuicVersionManager() {}
-
 AckListenerWrapper::AckListenerWrapper(QuicAckListenerInterface* listener,
                                        QuicPacketLength data_length)
     : ack_listener(listener), length(data_length) {
   DCHECK(listener != nullptr);
 }
 
 AckListenerWrapper::AckListenerWrapper(const AckListenerWrapper& other) =
     default;
 
 AckListenerWrapper::~AckListenerWrapper() {}
@@ skipping 53 matching lines @@
       is_unackable(false),
       has_crypto_handshake(has_crypto_handshake),
       num_padding_bytes(num_padding_bytes),
       retransmission(0) {}
 
 TransmissionInfo::TransmissionInfo(const TransmissionInfo& other) = default;
 
 TransmissionInfo::~TransmissionInfo() {}
 
 }  // namespace net