Add alternate server address to QuicConfig.

net/quic/crypto/crypto_protocol.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_CRYPTO_CRYPTO_PROTOCOL_H_
 #define NET_QUIC_CRYPTO_CRYPTO_PROTOCOL_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 156 matching lines @@
 const QuicTag kXLCT = TAG('X', 'L', 'C', 'T');   // Expected leaf certificate.
 const QuicTag kTBKP = TAG('T', 'B', 'K', 'P');   // Token Binding key params.
 
 // Rejection tags
 const QuicTag kRREJ = TAG('R', 'R', 'E', 'J');   // Reasons for server sending
 // Stateless Reject tags
 const QuicTag kRCID = TAG('R', 'C', 'I', 'D');   // Server-designated
                                                  // connection ID
 // Server hello tags
 const QuicTag kCADR = TAG('C', 'A', 'D', 'R');   // Client IP address and port
+const QuicTag kASAD = TAG('A', 'S', 'A', 'D');   // Alternate Server IP address
+                                                 // and port.
 
 // CETV tags
 const QuicTag kCIDK = TAG('C', 'I', 'D', 'K');   // ChannelID key
 const QuicTag kCIDS = TAG('C', 'I', 'D', 'S');   // ChannelID signature
 
 // Public reset tags
 const QuicTag kRNON = TAG('R', 'N', 'O', 'N');   // Public reset nonce proof
 const QuicTag kRSEQ = TAG('R', 'S', 'E', 'Q');   // Rejected packet number
 
 // Universal tags
@@ skipping 50 matching lines @@
 // amplification factor of any mirror DoS attack.
 //
 // A client may pad an inchoate client hello to a size larger than
 // kClientHelloMinimumSize to make it more likely to receive a complete
 // rejection message.
 const size_t kClientHelloMinimumSize = 1024;
 
 }  // namespace net
 
 #endif  // NET_QUIC_CRYPTO_CRYPTO_PROTOCOL_H_