Factoring a QuicCryptoServerStreamBase API out of QuicCryptoServerStream

net/quic/crypto/quic_crypto_server_config.cc

 // Copyright 2013 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/crypto/quic_crypto_server_config.h"
 
 #include <stdlib.h>
 #include <algorithm>
 
 #include "base/stl_util.h"
@@ skipping 529 matching lines @@
     QuicCryptoNegotiatedParameters* params,
     QuicCryptoProof* crypto_proof,
     CryptoHandshakeMessage* out,
     string* error_details) const {
   DCHECK(error_details);
 
   const CryptoHandshakeMessage& client_hello =
       validate_chlo_result.client_hello;
   const ClientHelloInfo& info = validate_chlo_result.info;
 
-  // If the client's preferred version is not the version we are currently
-  // speaking, then the client went through a version negotiation.  In this
-  // case, we need to make sure that we actually do not support this version
-  // and that it wasn't a downgrade attack.
-  QuicTag client_version_tag;
-  if (client_hello.GetUint32(kVER, &client_version_tag) != QUIC_NO_ERROR) {
-    *error_details = "client hello missing version list";
-    return QUIC_INVALID_CRYPTO_MESSAGE_PARAMETER;
-  }
-  QuicVersion client_version = QuicTagToQuicVersion(client_version_tag);
-  if (client_version != version) {
-    // Just because client_version is a valid version enum doesn't mean that
-    // this server actually supports that version, so we check to see if
-    // it's actually in the supported versions list.
-    for (size_t i = 0; i < supported_versions.size(); ++i) {
-      if (client_version == supported_versions[i]) {
-        *error_details = "Downgrade attack detected";
-        return QUIC_VERSION_NEGOTIATION_MISMATCH;
-      }
-    }
-  }
+  QuicErrorCode valid = CryptoUtils::ValidateClientHello(
+      client_hello, version, supported_versions, error_details);
+  if (valid != QUIC_NO_ERROR)
+    return valid;
 
   StringPiece requested_scid;
   client_hello.GetStringPiece(kSCID, &requested_scid);
   const QuicWallTime now(clock->WallNow());
 
   scoped_refptr<Config> requested_config;
   scoped_refptr<Config> primary_config;
   {
     base::AutoLock locked(configs_lock_);
 
@@ skipping 1160 matching lines @@
 QuicCryptoServerConfig::Config::Config()
     : channel_id_enabled(false),
       is_primary(false),
       primary_time(QuicWallTime::Zero()),
       priority(0),
       source_address_token_boxer(nullptr) {}
 
 QuicCryptoServerConfig::Config::~Config() { STLDeleteElements(&key_exchanges); }
 
 }  // namespace net