Adding an option for peers to negotiate the length of the QUIC

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 <string>
 
 #include "net/base/net_export.h"
@@ skipping 43 matching lines @@
 const QuicTag kTBBR = TAG('T', 'B', 'B', 'R');   // Reduced Buffer Bloat TCP
 const QuicTag kRENO = TAG('R', 'E', 'N', 'O');   // Reno Congestion Control
 const QuicTag kIW10 = TAG('I', 'W', '1', '0');   // Force ICWND to 10
 const QuicTag kPACE = TAG('P', 'A', 'C', 'E');   // Paced TCP cubic
 const QuicTag k1CON = TAG('1', 'C', 'O', 'N');   // Emulate a single connection
 
 // Loss detection algorithm types
 const QuicTag kNACK = TAG('N', 'A', 'C', 'K');   // TCP style nack counting
 const QuicTag kTIME = TAG('T', 'I', 'M', 'E');   // Time based
 
+// Optional support of truncated Connection IDs.  If sent by a peer, the value
+// is the minimum number of bytes allowed for the connection ID sent to the
+// peer.
+const QuicTag kTCID = TAG('T', 'C', 'I', 'D');   // Connection ID truncation.
+
 // FEC options
 const QuicTag kFHDR = TAG('F', 'H', 'D', 'R');   // FEC protect headers
 
 // Proof types (i.e. certificate types)
 // NOTE: although it would be silly to do so, specifying both kX509 and kX59R
 // is allowed and is equivalent to specifying only kX509.
 const QuicTag kX509 = TAG('X', '5', '0', '9');   // X.509 certificate, all key
                                                  // types
 const QuicTag kX59R = TAG('X', '5', '9', 'R');   // X.509 certificate, RSA keys
                                                  // only
@@ skipping 91 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_