1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4 
5 #ifndef QUICHE_QUIC_CORE_CRYPTO_CRYPTO_PROTOCOL_H_
6 #define QUICHE_QUIC_CORE_CRYPTO_CRYPTO_PROTOCOL_H_
7 
8 #include <cstddef>
9 #include <string>
10 
11 #include "net/third_party/quiche/src/quic/core/quic_tag.h"
12 
13 // Version and Crypto tags are written to the wire with a big-endian
14 // representation of the name of the tag.  For example
15 // the client hello tag (CHLO) will be written as the
16 // following 4 bytes: 'C' 'H' 'L' 'O'.  Since it is
17 // stored in memory as a little endian uint32_t, we need
18 // to reverse the order of the bytes.
19 //
20 // We use a macro to ensure that no static initialisers are created. Use the
21 // MakeQuicTag function in normal code.
22 #define TAG(a, b, c, d) \
23   static_cast<QuicTag>((d << 24) + (c << 16) + (b << 8) + a)
24 
25 namespace quic {
26 
27 using ServerConfigID = std::string;
28 
29 // The following tags have been deprecated and should not be reused:
30 // "1CON", "BBQ4", "NCON", "RCID", "SREJ", "TBKP", "TB10", "SCLS", "SMHL",
31 // "QNZR", "B2HI"
32 
33 // clang-format off
34 const QuicTag kCHLO = TAG('C', 'H', 'L', 'O');   // Client hello
35 const QuicTag kSHLO = TAG('S', 'H', 'L', 'O');   // Server hello
36 const QuicTag kSCFG = TAG('S', 'C', 'F', 'G');   // Server config
37 const QuicTag kREJ  = TAG('R', 'E', 'J', '\0');  // Reject
38 const QuicTag kCETV = TAG('C', 'E', 'T', 'V');   // Client encrypted tag-value
39                                                  // pairs
40 const QuicTag kPRST = TAG('P', 'R', 'S', 'T');   // Public reset
41 const QuicTag kSCUP = TAG('S', 'C', 'U', 'P');   // Server config update
42 const QuicTag kALPN = TAG('A', 'L', 'P', 'N');   // Application-layer protocol
43 
44 // Key exchange methods
45 const QuicTag kP256 = TAG('P', '2', '5', '6');   // ECDH, Curve P-256
46 const QuicTag kC255 = TAG('C', '2', '5', '5');   // ECDH, Curve25519
47 
48 // AEAD algorithms
49 const QuicTag kAESG = TAG('A', 'E', 'S', 'G');   // AES128 + GCM-12
50 const QuicTag kCC20 = TAG('C', 'C', '2', '0');   // ChaCha20 + Poly1305 RFC7539
51 
52 // Congestion control feedback types
53 const QuicTag kQBIC = TAG('Q', 'B', 'I', 'C');   // TCP cubic
54 
55 // Connection options (COPT) values
56 const QuicTag kAFCW = TAG('A', 'F', 'C', 'W');   // Auto-tune flow control
57                                                  // receive windows.
58 const QuicTag kIFW5 = TAG('I', 'F', 'W', '5');   // Set initial size
59                                                  // of stream flow control
60                                                  // receive window to
61                                                  // 32KB. (2^5 KB).
62 const QuicTag kIFW6 = TAG('I', 'F', 'W', '6');   // Set initial size
63                                                  // of stream flow control
64                                                  // receive window to
65                                                  // 64KB. (2^6 KB).
66 const QuicTag kIFW7 = TAG('I', 'F', 'W', '7');   // Set initial size
67                                                  // of stream flow control
68                                                  // receive window to
69                                                  // 128KB. (2^7 KB).
70 const QuicTag kIFW8 = TAG('I', 'F', 'W', '8');   // Set initial size
71                                                  // of stream flow control
72                                                  // receive window to
73                                                  // 256KB. (2^8 KB).
74 const QuicTag kIFW9 = TAG('I', 'F', 'W', '9');   // Set initial size
75                                                  // of stream flow control
76                                                  // receive window to
77                                                  // 512KB. (2^9 KB).
78 const QuicTag kIFWA = TAG('I', 'F', 'W', 'a');   // Set initial size
79                                                  // of stream flow control
80                                                  // receive window to
81                                                  // 1MB. (2^0xa KB).
82 const QuicTag kTBBR = TAG('T', 'B', 'B', 'R');   // Reduced Buffer Bloat TCP
83 const QuicTag k1RTT = TAG('1', 'R', 'T', 'T');   // STARTUP in BBR for 1 RTT
84 const QuicTag k2RTT = TAG('2', 'R', 'T', 'T');   // STARTUP in BBR for 2 RTTs
85 const QuicTag kLRTT = TAG('L', 'R', 'T', 'T');   // Exit STARTUP in BBR on loss
86 const QuicTag kBBS1 = TAG('B', 'B', 'S', '1');   // DEPRECATED
87 const QuicTag kBBS2 = TAG('B', 'B', 'S', '2');   // More aggressive packet
88                                                  // conservation in BBR STARTUP
89 const QuicTag kBBS3 = TAG('B', 'B', 'S', '3');   // Slowstart packet
90                                                  // conservation in BBR STARTUP
91 const QuicTag kBBS4 = TAG('B', 'B', 'S', '4');   // DEPRECATED
92 const QuicTag kBBS5 = TAG('B', 'B', 'S', '5');   // DEPRECATED
93 const QuicTag kBBRR = TAG('B', 'B', 'R', 'R');   // Rate-based recovery in BBR
94 const QuicTag kBBR1 = TAG('B', 'B', 'R', '1');   // DEPRECATED
95 const QuicTag kBBR2 = TAG('B', 'B', 'R', '2');   // DEPRECATED
96 const QuicTag kBBR3 = TAG('B', 'B', 'R', '3');   // Fully drain the queue once
97                                                  // per cycle
98 const QuicTag kBBR4 = TAG('B', 'B', 'R', '4');   // 20 RTT ack aggregation
99 const QuicTag kBBR5 = TAG('B', 'B', 'R', '5');   // 40 RTT ack aggregation
100 const QuicTag kBBR9 = TAG('B', 'B', 'R', '9');   // DEPRECATED
101 const QuicTag kBBRS = TAG('B', 'B', 'R', 'S');   // DEPRECATED
102 const QuicTag kBBQ1 = TAG('B', 'B', 'Q', '1');   // BBR with lower 2.77 STARTUP
103                                                  // pacing and CWND gain.
104 const QuicTag kBBQ2 = TAG('B', 'B', 'Q', '2');   // BBRv2 with 2.885 STARTUP and
105                                                  // DRAIN CWND gain.
106 const QuicTag kBBQ3 = TAG('B', 'B', 'Q', '3');   // BBR with ack aggregation
107                                                  // compensation in STARTUP.
108 const QuicTag kBBQ5 = TAG('B', 'B', 'Q', '5');   // Expire ack aggregation upon
109                                                  // bandwidth increase in
110                                                  // STARTUP.
111 const QuicTag kRENO = TAG('R', 'E', 'N', 'O');   // Reno Congestion Control
112 const QuicTag kTPCC = TAG('P', 'C', 'C', '\0');  // Performance-Oriented
113                                                  // Congestion Control
114 const QuicTag kBYTE = TAG('B', 'Y', 'T', 'E');   // TCP cubic or reno in bytes
115 const QuicTag kIW03 = TAG('I', 'W', '0', '3');   // Force ICWND to 3
116 const QuicTag kIW10 = TAG('I', 'W', '1', '0');   // Force ICWND to 10
117 const QuicTag kIW20 = TAG('I', 'W', '2', '0');   // Force ICWND to 20
118 const QuicTag kIW50 = TAG('I', 'W', '5', '0');   // Force ICWND to 50
119 const QuicTag kB2ON = TAG('B', '2', 'O', 'N');   // Enable BBRv2
120 const QuicTag kB2NA = TAG('B', '2', 'N', 'A');   // For BBRv2, do not add ack
121                                                  // height to queueing threshold
122 const QuicTag kB2NE = TAG('B', '2', 'N', 'E');   // For BBRv2, do not exit
123                                                  // STARTUP if there's enough
124                                                  // bandwidth growth
125 const QuicTag kB2RP = TAG('B', '2', 'R', 'P');   // For BBRv2, run PROBE_RTT on
126                                                  // the regular schedule
127 const QuicTag kB2CL = TAG('B', '2', 'C', 'L');   // For BBRv2, allow PROBE_BW
128                                                  // cwnd to be below BDP + ack
129                                                  // height.
130 const QuicTag kB2LO = TAG('B', '2', 'L', 'O');   // Ignore inflight_lo in BBR2
131 const QuicTag kB2HR = TAG('B', '2', 'H', 'R');   // 15% inflight_hi headroom.
132 const QuicTag kB2SL = TAG('B', '2', 'S', 'L');   // When exiting STARTUP due to
133                                                  // loss, set inflight_hi to the
134                                                  // max of bdp and max bytes
135                                                  // delivered in round.
136 const QuicTag kB2H2 = TAG('B', '2', 'H', '2');   // When exiting PROBE_UP due to
137                                                  // loss, set inflight_hi to the
138                                                  // max of inflight@send and max
139                                                  // bytes delivered in round.
140 const QuicTag kBSAO = TAG('B', 'S', 'A', 'O');   // Avoid Overestimation in
141                                                  // Bandwidth Sampler with ack
142                                                  // aggregation
143 const QuicTag kNTLP = TAG('N', 'T', 'L', 'P');   // No tail loss probe
144 const QuicTag k1TLP = TAG('1', 'T', 'L', 'P');   // 1 tail loss probe
145 const QuicTag k1RTO = TAG('1', 'R', 'T', 'O');   // Send 1 packet upon RTO
146 const QuicTag kNRTO = TAG('N', 'R', 'T', 'O');   // CWND reduction on loss
147 const QuicTag kTIME = TAG('T', 'I', 'M', 'E');   // Time based loss detection
148 const QuicTag kATIM = TAG('A', 'T', 'I', 'M');   // Adaptive time loss detection
149 const QuicTag kMIN1 = TAG('M', 'I', 'N', '1');   // Min CWND of 1 packet
150 const QuicTag kMIN4 = TAG('M', 'I', 'N', '4');   // Min CWND of 4 packets,
151                                                  // with a min rate of 1 BDP.
152 const QuicTag kTLPR = TAG('T', 'L', 'P', 'R');   // Tail loss probe delay of
153                                                  // 0.5RTT.
154 const QuicTag kMAD0 = TAG('M', 'A', 'D', '0');   // Ignore ack delay
155 const QuicTag kMAD1 = TAG('M', 'A', 'D', '1');   // 25ms initial max ack delay
156 const QuicTag kMAD2 = TAG('M', 'A', 'D', '2');   // No min TLP
157 const QuicTag kMAD3 = TAG('M', 'A', 'D', '3');   // No min RTO
158 const QuicTag kMAD4 = TAG('M', 'A', 'D', '4');   // IETF style TLP
159 const QuicTag kMAD5 = TAG('M', 'A', 'D', '5');   // IETF style TLP with 2x mult
160 const QuicTag k1ACK = TAG('1', 'A', 'C', 'K');   // 1 fast ack for reordering
161 const QuicTag kACD0 = TAG('A', 'D', 'D', '0');   // Disable ack decimation
162 const QuicTag kACKD = TAG('A', 'C', 'K', 'D');   // Ack decimation style acking.
163 const QuicTag kAKD2 = TAG('A', 'K', 'D', '2');   // Ack decimation tolerating
164                                                  // out of order packets.
165 const QuicTag kAKD3 = TAG('A', 'K', 'D', '3');   // Ack decimation style acking
166                                                  // with 1/8 RTT acks.
167 const QuicTag kAKD4 = TAG('A', 'K', 'D', '4');   // Ack decimation with 1/8 RTT
168                                                  // tolerating out of order.
169 const QuicTag kAKDU = TAG('A', 'K', 'D', 'U');   // Unlimited number of packets
170                                                  // received before acking
171 const QuicTag kACKQ = TAG('A', 'C', 'K', 'Q');   // Send an immediate ack after
172                                                  // 1 RTT of not receiving.
173 const QuicTag kAFFE = TAG('A', 'F', 'F', 'E');   // Enable client receiving
174                                                  // AckFrequencyFrame.
175 const QuicTag kAFF1 = TAG('A', 'F', 'F', '1');   // Use SRTT in building
176                                                  // AckFrequencyFrame.
177 const QuicTag kAFF2 = TAG('A', 'F', 'F', '2');   // Send AckFrequencyFrame upon
178                                                  // handshake completion.
179 const QuicTag kSSLR = TAG('S', 'S', 'L', 'R');   // Slow Start Large Reduction.
180 const QuicTag kNPRR = TAG('N', 'P', 'R', 'R');   // Pace at unity instead of PRR
181 const QuicTag k2RTO = TAG('2', 'R', 'T', 'O');   // Close connection on 2 RTOs
182 const QuicTag k3RTO = TAG('3', 'R', 'T', 'O');   // Close connection on 3 RTOs
183 const QuicTag k4RTO = TAG('4', 'R', 'T', 'O');   // Close connection on 4 RTOs
184 const QuicTag k5RTO = TAG('5', 'R', 'T', 'O');   // Close connection on 5 RTOs
185 const QuicTag k6RTO = TAG('6', 'R', 'T', 'O');   // Close connection on 6 RTOs
186 const QuicTag kCBHD = TAG('C', 'B', 'H', 'D');   // Client only blackhole
187                                                  // detection.
188 const QuicTag kNBHD = TAG('N', 'B', 'H', 'D');   // No blackhole detection.
189 const QuicTag kCONH = TAG('C', 'O', 'N', 'H');   // Conservative Handshake
190                                                  // Retransmissions.
191 const QuicTag kLFAK = TAG('L', 'F', 'A', 'K');   // Don't invoke FACK on the
192                                                  // first ack.
193 const QuicTag kSTMP = TAG('S', 'T', 'M', 'P');   // Send and process timestamps
194 const QuicTag kEACK = TAG('E', 'A', 'C', 'K');   // Bundle ack-eliciting frame
195                                                  // with an ACK after PTO/RTO
196 
197 const QuicTag kILD0 = TAG('I', 'L', 'D', '0');   // IETF style loss detection
198                                                  // (default with 1/8 RTT time
199                                                  // threshold)
200 const QuicTag kILD1 = TAG('I', 'L', 'D', '1');   // IETF style loss detection
201                                                  // with 1/4 RTT time threshold
202 const QuicTag kILD2 = TAG('I', 'L', 'D', '2');   // IETF style loss detection
203                                                  // with adaptive packet
204                                                  // threshold
205 const QuicTag kILD3 = TAG('I', 'L', 'D', '3');   // IETF style loss detection
206                                                  // with 1/4 RTT time threshold
207                                                  // and adaptive packet
208                                                  // threshold
209 const QuicTag kILD4 = TAG('I', 'L', 'D', '4');   // IETF style loss detection
210                                                  // with both adaptive time
211                                                  // threshold (default 1/4 RTT)
212                                                  // and adaptive packet
213                                                  // threshold
214 const QuicTag kRUNT = TAG('R', 'U', 'N', 'T');   // No packet threshold loss
215                                                  // detection for "runt" packet.
216 const QuicTag kNSTP = TAG('N', 'S', 'T', 'P');   // No stop waiting frames.
217 const QuicTag kNRTT = TAG('N', 'R', 'T', 'T');   // Ignore initial RTT
218 
219 const QuicTag k1PTO = TAG('1', 'P', 'T', 'O');   // Send 1 packet upon PTO.
220 const QuicTag k2PTO = TAG('2', 'P', 'T', 'O');   // Send 2 packets upon PTO.
221 
222 const QuicTag k6PTO = TAG('6', 'P', 'T', 'O');   // Closes connection on 6
223                                                  // consecutive PTOs.
224 const QuicTag k7PTO = TAG('7', 'P', 'T', 'O');   // Closes connection on 7
225                                                  // consecutive PTOs.
226 const QuicTag k8PTO = TAG('8', 'P', 'T', 'O');   // Closes connection on 8
227                                                  // consecutive PTOs.
228 const QuicTag kPTOS = TAG('P', 'T', 'O', 'S');   // Skip packet number before
229                                                  // sending the last PTO.
230 const QuicTag kPTOA = TAG('P', 'T', 'O', 'A');   // Do not add max ack delay
231                                                  // when computing PTO timeout
232                                                  // if an immediate ACK is
233                                                  // expected.
234 const QuicTag kPEB1 = TAG('P', 'E', 'B', '1');   // Start exponential backoff
235                                                  // since 1st PTO.
236 const QuicTag kPEB2 = TAG('P', 'E', 'B', '2');   // Start exponential backoff
237                                                  // since 2nd PTO.
238 const QuicTag kPVS1 = TAG('P', 'V', 'S', '1');   // Use 2 * rttvar when
239                                                  // calculating PTO timeout.
240 const QuicTag kPAG1 = TAG('P', 'A', 'G', '1');   // Make 1st PTO more aggressive
241 const QuicTag kPAG2 = TAG('P', 'A', 'G', '2');   // Make first 2 PTOs more
242                                                  // aggressive
243 const QuicTag kPSDA = TAG('P', 'S', 'D', 'A');   // Use standard deviation when
244                                                  // calculating PTO timeout.
245 const QuicTag kPLE1 = TAG('P', 'L', 'E', '1');   // Arm the 1st PTO with
246                                                  // earliest in flight sent time
247                                                  // and at least 0.5*srtt from
248                                                  // last sent packet.
249 const QuicTag kPLE2 = TAG('P', 'L', 'E', '2');   // Arm the 1st PTO with
250                                                  // earliest in flight sent time
251                                                  // and at least 1.5*srtt from
252                                                  // last sent packet.
253 const QuicTag kAPTO = TAG('A', 'P', 'T', 'O');   // Use 1.5 * initial RTT before
254                                                  // any RTT sample is available.
255 
256 const QuicTag kELDT = TAG('E', 'L', 'D', 'T');   // Enable Loss Detection Tuning
257 
258 // Optional support of truncated Connection IDs.  If sent by a peer, the value
259 // is the minimum number of bytes allowed for the connection ID sent to the
260 // peer.
261 const QuicTag kTCID = TAG('T', 'C', 'I', 'D');   // Connection ID truncation.
262 
263 // Multipath option.
264 const QuicTag kMPTH = TAG('M', 'P', 'T', 'H');   // Enable multipath.
265 
266 const QuicTag kNCMR = TAG('N', 'C', 'M', 'R');   // Do not attempt connection
267                                                  // migration.
268 
269 // Disable Pacing offload option.
270 const QuicTag kNPCO = TAG('N', 'P', 'C', 'O');    // No pacing offload.
271 
272 // Enable bandwidth resumption experiment.
273 const QuicTag kBWRE = TAG('B', 'W', 'R', 'E');  // Bandwidth resumption.
274 const QuicTag kBWMX = TAG('B', 'W', 'M', 'X');  // Max bandwidth resumption.
275 const QuicTag kBWRS = TAG('B', 'W', 'R', 'S');  // Server bandwidth resumption.
276 const QuicTag kBWS2 = TAG('B', 'W', 'S', '2');  // Server bw resumption v2.
277 const QuicTag kBWS3 = TAG('B', 'W', 'S', '3');  // QUIC Initial CWND - Control.
278 const QuicTag kBWS4 = TAG('B', 'W', 'S', '4');  // QUIC Initial CWND - Enabled.
279 const QuicTag kBWS5 = TAG('B', 'W', 'S', '5');  // QUIC Initial CWND up and down
280 const QuicTag kBWS6 = TAG('B', 'W', 'S', '6');  // QUIC Initial CWND - Enabled
281                                                 // with 0.5 * default
282                                                 // multiplier.
283 const QuicTag kBWP0 = TAG('B', 'W', 'P', '0');  // QUIC Initial CWND - SPDY
284                                                 // priority 0.
285 const QuicTag kBWP1 = TAG('B', 'W', 'P', '1');  // QUIC Initial CWND - SPDY
286                                                 // priorities 0 and 1.
287 const QuicTag kBWP2 = TAG('B', 'W', 'P', '2');  // QUIC Initial CWND - SPDY
288                                                 // priorities 0, 1 and 2.
289 const QuicTag kBWP3 = TAG('B', 'W', 'P', '3');  // QUIC Initial CWND - SPDY
290                                                 // priorities 0, 1, 2 and 3.
291 const QuicTag kBWP4 = TAG('B', 'W', 'P', '4');  // QUIC Initial CWND - SPDY
292                                                 // priorities >= 0, 1, 2, 3 and
293                                                 // 4.
294 const QuicTag kBWG4 = TAG('B', 'W', 'G', '4');  // QUIC Initial CWND -
295                                                 // Bandwidth model 1.
296 const QuicTag kBWG7 = TAG('B', 'W', 'G', '7');  // QUIC Initial CWND -
297                                                 // Bandwidth model 2.
298 const QuicTag kBWG8 = TAG('B', 'W', 'G', '8');  // QUIC Initial CWND -
299                                                 // Bandwidth model 3.
300 const QuicTag kBWS7 = TAG('B', 'W', 'S', '7');  // QUIC Initial CWND - Enabled
301                                                 // with 0.75 * default
302                                                 // multiplier.
303 const QuicTag kBWM3 = TAG('B', 'W', 'M', '3');  // Consider overshooting if
304                                                 // bytes lost after bandwidth
305                                                 // resumption * 3 > IW.
306 const QuicTag kBWM4 = TAG('B', 'W', 'M', '4');  // Consider overshooting if
307                                                 // bytes lost after bandwidth
308                                                 // resumption * 4 > IW.
309 const QuicTag kICW1 = TAG('I', 'C', 'W', '1');  // Max initial congestion window
310                                                 // 100.
311 const QuicTag kDTOS = TAG('D', 'T', 'O', 'S');  // Enable overshooting
312                                                 // detection.
313 
314 const QuicTag kFIDT = TAG('F', 'I', 'D', 'T');  // Extend idle timer by PTO
315                                                 // instead of the whole idle
316                                                 // timeout.
317 
318 const QuicTag k3AFF = TAG('3', 'A', 'F', 'F');  // 3 anti amplification factor.
319 const QuicTag k10AF = TAG('1', '0', 'A', 'F');  // 10 anti amplification factor.
320 
321 // Enable path MTU discovery experiment.
322 const QuicTag kMTUH = TAG('M', 'T', 'U', 'H');  // High-target MTU discovery.
323 const QuicTag kMTUL = TAG('M', 'T', 'U', 'L');  // Low-target MTU discovery.
324 
325 // Enable Priority scheme experiment.
326 const QuicTag kH2PR = TAG('H', '2', 'P', 'R');  // HTTP2 priorities.
327 const QuicTag kFIFO = TAG('F', 'I', 'F', 'O');  // Stream with the smallest ID
328                                                 // has the highest priority.
329 const QuicTag kLIFO = TAG('L', 'I', 'F', 'O');  // Stream with the largest ID
330                                                 // has the highest priority.
331 const QuicTag kRRWS = TAG('R', 'R', 'W', 'S');  // Round robin write scheduling.
332 
333 const QuicTag kNSLC = TAG('N', 'S', 'L', 'C');  // Always send connection close
334                                                 // for idle timeout.
335 
336 // Proof types (i.e. certificate types)
337 // NOTE: although it would be silly to do so, specifying both kX509 and kX59R
338 // is allowed and is equivalent to specifying only kX509.
339 const QuicTag kX509 = TAG('X', '5', '0', '9');   // X.509 certificate, all key
340                                                  // types
341 const QuicTag kX59R = TAG('X', '5', '9', 'R');   // X.509 certificate, RSA keys
342                                                  // only
343 const QuicTag kCHID = TAG('C', 'H', 'I', 'D');   // Channel ID.
344 
345 // Client hello tags
346 const QuicTag kVER  = TAG('V', 'E', 'R', '\0');  // Version
347 const QuicTag kNONC = TAG('N', 'O', 'N', 'C');   // The client's nonce
348 const QuicTag kNONP = TAG('N', 'O', 'N', 'P');   // The client's proof nonce
349 const QuicTag kKEXS = TAG('K', 'E', 'X', 'S');   // Key exchange methods
350 const QuicTag kAEAD = TAG('A', 'E', 'A', 'D');   // Authenticated
351                                                  // encryption algorithms
352 const QuicTag kCOPT = TAG('C', 'O', 'P', 'T');   // Connection options
353 const QuicTag kCLOP = TAG('C', 'L', 'O', 'P');   // Client connection options
354 const QuicTag kICSL = TAG('I', 'C', 'S', 'L');   // Idle network timeout
355 const QuicTag kMIBS = TAG('M', 'I', 'D', 'S');   // Max incoming bidi streams
356 const QuicTag kMIUS = TAG('M', 'I', 'U', 'S');   // Max incoming unidi streams
357 const QuicTag kADE  = TAG('A', 'D', 'E', 0);     // Ack Delay Exponent (IETF
358                                                  // QUIC ACK Frame Only).
359 const QuicTag kIRTT = TAG('I', 'R', 'T', 'T');   // Estimated initial RTT in us.
360 const QuicTag kSNI  = TAG('S', 'N', 'I', '\0');  // Server name
361                                                  // indication
362 const QuicTag kPUBS = TAG('P', 'U', 'B', 'S');   // Public key values
363 const QuicTag kSCID = TAG('S', 'C', 'I', 'D');   // Server config id
364 const QuicTag kORBT = TAG('O', 'B', 'I', 'T');   // Server orbit.
365 const QuicTag kPDMD = TAG('P', 'D', 'M', 'D');   // Proof demand.
366 const QuicTag kPROF = TAG('P', 'R', 'O', 'F');   // Proof (signature).
367 const QuicTag kCCS  = TAG('C', 'C', 'S', 0);     // Common certificate set
368 const QuicTag kCCRT = TAG('C', 'C', 'R', 'T');   // Cached certificate
369 const QuicTag kEXPY = TAG('E', 'X', 'P', 'Y');   // Expiry
370 const QuicTag kSTTL = TAG('S', 'T', 'T', 'L');   // Server Config TTL
371 const QuicTag kSFCW = TAG('S', 'F', 'C', 'W');   // Initial stream flow control
372                                                  // receive window.
373 const QuicTag kCFCW = TAG('C', 'F', 'C', 'W');   // Initial session/connection
374                                                  // flow control receive window.
375 const QuicTag kUAID = TAG('U', 'A', 'I', 'D');   // Client's User Agent ID.
376 const QuicTag kXLCT = TAG('X', 'L', 'C', 'T');   // Expected leaf certificate.
377 const QuicTag kQLVE = TAG('Q', 'L', 'V', 'E');   // Legacy Version
378                                                  // Encapsulation.
379 
380 const QuicTag kQNZ2 = TAG('Q', 'N', 'Z', '2');   // Turn off QUIC crypto 0-RTT.
381 
382 const QuicTag kQNSP = TAG('Q', 'N', 'S', 'P');   // Turn off server push in
383                                                  // gQUIC.
384 
385 const QuicTag kMAD  = TAG('M', 'A', 'D', 0);     // Max Ack Delay (IETF QUIC)
386 
387 // Rejection tags
388 const QuicTag kRREJ = TAG('R', 'R', 'E', 'J');   // Reasons for server sending
389 
390 // Server hello tags
391 const QuicTag kCADR = TAG('C', 'A', 'D', 'R');   // Client IP address and port
392 const QuicTag kASAD = TAG('A', 'S', 'A', 'D');   // Alternate Server IP address
393                                                  // and port.
394 const QuicTag kSRST = TAG('S', 'R', 'S', 'T');   // Stateless reset token used
395                                                  // in IETF public reset packet
396 
397 // CETV tags
398 const QuicTag kCIDK = TAG('C', 'I', 'D', 'K');   // ChannelID key
399 const QuicTag kCIDS = TAG('C', 'I', 'D', 'S');   // ChannelID signature
400 
401 // Public reset tags
402 const QuicTag kRNON = TAG('R', 'N', 'O', 'N');   // Public reset nonce proof
403 const QuicTag kRSEQ = TAG('R', 'S', 'E', 'Q');   // Rejected packet number
404 
405 // Universal tags
406 const QuicTag kPAD  = TAG('P', 'A', 'D', '\0');  // Padding
407 
408 // Stats collection tags
409 const QuicTag kEPID = TAG('E', 'P', 'I', 'D');  // Endpoint identifier.
410 
411 // clang-format on
412 
413 // These tags have a special form so that they appear either at the beginning
414 // or the end of a handshake message. Since handshake messages are sorted by
415 // tag value, the tags with 0 at the end will sort first and those with 255 at
416 // the end will sort last.
417 //
418 // The certificate chain should have a tag that will cause it to be sorted at
419 // the end of any handshake messages because it's likely to be large and the
420 // client might be able to get everything that it needs from the small values at
421 // the beginning.
422 //
423 // Likewise tags with random values should be towards the beginning of the
424 // message because the server mightn't hold state for a rejected client hello
425 // and therefore the client may have issues reassembling the rejection message
426 // in the event that it sent two client hellos.
427 const QuicTag kServerNonceTag = TAG('S', 'N', 'O', 0);  // The server's nonce
428 const QuicTag kSourceAddressTokenTag =
429     TAG('S', 'T', 'K', 0);  // Source-address token
430 const QuicTag kCertificateTag = TAG('C', 'R', 'T', 255);  // Certificate chain
431 const QuicTag kCertificateSCTTag =
432     TAG('C', 'S', 'C', 'T');  // Signed cert timestamp (RFC6962) of leaf cert.
433 
434 #undef TAG
435 
436 const size_t kMaxEntries = 128;  // Max number of entries in a message.
437 
438 const size_t kNonceSize = 32;  // Size in bytes of the connection nonce.
439 
440 const size_t kOrbitSize = 8;  // Number of bytes in an orbit value.
441 
442 // kProofSignatureLabel is prepended to the CHLO hash and server configs before
443 // signing to avoid any cross-protocol attacks on the signature.
444 const char kProofSignatureLabel[] = "QUIC CHLO and server config signature";
445 
446 // kClientHelloMinimumSize is the minimum size of a client hello. Client hellos
447 // will have PAD tags added in order to ensure this minimum is met and client
448 // hellos smaller than this will be an error. This minimum size reduces the
449 // amplification factor of any mirror DoS attack.
450 //
451 // A client may pad an inchoate client hello to a size larger than
452 // kClientHelloMinimumSize to make it more likely to receive a complete
453 // rejection message.
454 const size_t kClientHelloMinimumSize = 1024;
455 
456 }  // namespace quic
457 
458 #endif  // QUICHE_QUIC_CORE_CRYPTO_CRYPTO_PROTOCOL_H_
459