Prevent multiple simultaneous calls to GetProof

net/quic/core/quic_crypto_server_stream.h

 // 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.
 
 #ifndef NET_QUIC_CORE_QUIC_CRYPTO_SERVER_STREAM_H_
 #define NET_QUIC_CORE_QUIC_CRYPTO_SERVER_STREAM_H_
 
 #include <cstdint>
 #include <memory>
 #include <string>
@@ skipping 203 matching lines @@
   QuicCompressedCertsCache* compressed_certs_cache_;
 
   // Server's certificate chain and signature of the server config, as provided
   // by ProofSource::GetProof.
   QuicReferenceCountedPointer<QuicSignedServerConfig> signed_config_;
 
   // Hash of the last received CHLO message which can be used for generating
   // server config update messages.
   std::string chlo_hash_;
 
-  // Pointer to the active callback that will receive the result of
-  // the client hello validation request and forward it to
-  // FinishProcessingHandshakeMessage for processing.  nullptr if no
-  // handshake message is being validated.
-  ValidateCallback* validate_client_hello_cb_;
-
   // Pointer to the helper for this crypto stream. Must outlive this stream.
   Helper* helper_;
 
   // Number of handshake messages received by this stream.
   uint8_t num_handshake_messages_;
 
   // Number of handshake messages received by this stream that contain
   // server nonces (indicating that this is a non-zero-RTT handshake
   // attempt).
   uint8_t num_handshake_messages_with_server_nonces_;
@@ skipping 22 matching lines @@
 
   // Set to true, once the server has received information from the
   // client that it supports stateless reject.
   //  TODO(jokulik): Remove once client stateless reject support
   // becomes the default.
   bool peer_supports_stateless_rejects_;
 
   // Size of the packet containing the most recently received CHLO.
   QuicByteCount chlo_packet_size_;
 
+  // Pointer to the active callback that will receive the result of the client
+  // hello validation request and forward it to FinishProcessingHandshakeMessage
+  // for processing.  nullptr if no handshake message is being validated.  Note
+  // that this field is mutually exclusive with process_client_hello_cb_.
+  ValidateCallback* validate_client_hello_cb_;
+
   // Pointer to the active callback which will receive the results of
   // ProcessClientHello and forward it to
-  // FinishProcessingHandshakeMessageAfterProcessClientHello.
+  // FinishProcessingHandshakeMessageAfterProcessClientHello.  Note that this
+  // field is mutually exclusive with validate_client_hello_cb_.
   ProcessClientHelloCallback* process_client_hello_cb_;
 
   DISALLOW_COPY_AND_ASSIGN(QuicCryptoServerStream);
 };
 
 }  // namespace net
 
 #endif  // NET_QUIC_CORE_QUIC_CRYPTO_SERVER_STREAM_H_