FreeBSD kernel IPv4 code
tcp.h
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1 /*-
2  * SPDX-License-Identifier: BSD-3-Clause
3  *
4  * Copyright (c) 1982, 1986, 1993
5  * The Regents of the University of California. All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  * notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  * notice, this list of conditions and the following disclaimer in the
14  * documentation and/or other materials provided with the distribution.
15  * 3. Neither the name of the University nor the names of its contributors
16  * may be used to endorse or promote products derived from this software
17  * without specific prior written permission.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22  * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29  * SUCH DAMAGE.
30  *
31  * @(#)tcp.h 8.1 (Berkeley) 6/10/93
32  * $FreeBSD: head/sys/netinet/tcp.h 353328 2019-10-08 21:34:06Z jhb $
33  */
34 
35 #ifndef _NETINET_TCP_H_
36 #define _NETINET_TCP_H_
37 
38 #include <sys/cdefs.h>
39 #include <sys/types.h>
40 
41 #if __BSD_VISIBLE
42 
43 typedef u_int32_t tcp_seq;
44 
45 #define tcp6_seq tcp_seq /* for KAME src sync over BSD*'s */
46 #define tcp6hdr tcphdr /* for KAME src sync over BSD*'s */
47 
48 /*
49  * TCP header.
50  * Per RFC 793, September, 1981.
51  */
52 struct tcphdr {
53  u_short th_sport; /* source port */
54  u_short th_dport; /* destination port */
55  tcp_seq th_seq; /* sequence number */
56  tcp_seq th_ack; /* acknowledgement number */
57 #if BYTE_ORDER == LITTLE_ENDIAN
58  u_char th_x2:4, /* (unused) */
59  th_off:4; /* data offset */
60 #endif
61 #if BYTE_ORDER == BIG_ENDIAN
62  u_char th_off:4, /* data offset */
63  th_x2:4; /* (unused) */
64 #endif
65  u_char th_flags;
66 #define TH_FIN 0x01
67 #define TH_SYN 0x02
68 #define TH_RST 0x04
69 #define TH_PUSH 0x08
70 #define TH_ACK 0x10
71 #define TH_URG 0x20
72 #define TH_ECE 0x40
73 #define TH_CWR 0x80
74 #define TH_FLAGS (TH_FIN|TH_SYN|TH_RST|TH_PUSH|TH_ACK|TH_URG|TH_ECE|TH_CWR)
75 #define PRINT_TH_FLAGS "\20\1FIN\2SYN\3RST\4PUSH\5ACK\6URG\7ECE\10CWR"
76 
77  u_short th_win; /* window */
78  u_short th_sum; /* checksum */
79  u_short th_urp; /* urgent pointer */
80 };
81 
82 #define TCPOPT_EOL 0
83 #define TCPOLEN_EOL 1
84 #define TCPOPT_PAD 0 /* padding after EOL */
85 #define TCPOLEN_PAD 1
86 #define TCPOPT_NOP 1
87 #define TCPOLEN_NOP 1
88 #define TCPOPT_MAXSEG 2
89 #define TCPOLEN_MAXSEG 4
90 #define TCPOPT_WINDOW 3
91 #define TCPOLEN_WINDOW 3
92 #define TCPOPT_SACK_PERMITTED 4
93 #define TCPOLEN_SACK_PERMITTED 2
94 #define TCPOPT_SACK 5
95 #define TCPOLEN_SACKHDR 2
96 #define TCPOLEN_SACK 8 /* 2*sizeof(tcp_seq) */
97 #define TCPOPT_TIMESTAMP 8
98 #define TCPOLEN_TIMESTAMP 10
99 #define TCPOLEN_TSTAMP_APPA (TCPOLEN_TIMESTAMP+2) /* appendix A */
100 #define TCPOPT_SIGNATURE 19 /* Keyed MD5: RFC 2385 */
101 #define TCPOLEN_SIGNATURE 18
102 #define TCPOPT_FAST_OPEN 34
103 #define TCPOLEN_FAST_OPEN_EMPTY 2
104 
105 /* Miscellaneous constants */
106 #define MAX_SACK_BLKS 6 /* Max # SACK blocks stored at receiver side */
107 #define TCP_MAX_SACK 4 /* MAX # SACKs sent in any segment */
108 
109 
110 /*
111  * The default maximum segment size (MSS) to be used for new TCP connections
112  * when path MTU discovery is not enabled.
113  *
114  * RFC879 derives the default MSS from the largest datagram size hosts are
115  * minimally required to handle directly or through IP reassembly minus the
116  * size of the IP and TCP header. With IPv6 the minimum MTU is specified
117  * in RFC2460.
118  *
119  * For IPv4 the MSS is 576 - sizeof(struct tcpiphdr)
120  * For IPv6 the MSS is IPV6_MMTU - sizeof(struct ip6_hdr) - sizeof(struct tcphdr)
121  *
122  * We use explicit numerical definition here to avoid header pollution.
123  */
124 #define TCP_MSS 536
125 #define TCP6_MSS 1220
126 
127 /*
128  * Limit the lowest MSS we accept for path MTU discovery and the TCP SYN MSS
129  * option. Allowing low values of MSS can consume significant resources and
130  * be used to mount a resource exhaustion attack.
131  * Connections requesting lower MSS values will be rounded up to this value
132  * and the IP_DF flag will be cleared to allow fragmentation along the path.
133  *
134  * See tcp_subr.c tcp_minmss SYSCTL declaration for more comments. Setting
135  * it to "0" disables the minmss check.
136  *
137  * The default value is fine for TCP across the Internet's smallest official
138  * link MTU (256 bytes for AX.25 packet radio). However, a connection is very
139  * unlikely to come across such low MTU interfaces these days (anno domini 2003).
140  */
141 #define TCP_MINMSS 216
142 
143 #define TCP_MAXWIN 65535 /* largest value for (unscaled) window */
144 #define TTCP_CLIENT_SND_WND 4096 /* dflt send window for T/TCP client */
145 
146 #define TCP_MAX_WINSHIFT 14 /* maximum window shift */
147 
148 #define TCP_MAXBURST 4 /* maximum segments in a burst */
149 
150 #define TCP_MAXHLEN (0xf<<2) /* max length of header in bytes */
151 #define TCP_MAXOLEN (TCP_MAXHLEN - sizeof(struct tcphdr))
152  /* max space left for options */
153 
154 #define TCP_FASTOPEN_MIN_COOKIE_LEN 4 /* Per RFC7413 */
155 #define TCP_FASTOPEN_MAX_COOKIE_LEN 16 /* Per RFC7413 */
156 #define TCP_FASTOPEN_PSK_LEN 16 /* Same as TCP_FASTOPEN_KEY_LEN */
157 #endif /* __BSD_VISIBLE */
158 
159 /*
160  * User-settable options (used with setsockopt). These are discrete
161  * values and are not masked together. Some values appear to be
162  * bitmasks for historical reasons.
163  */
164 #define TCP_NODELAY 1 /* don't delay send to coalesce packets */
165 #if __BSD_VISIBLE
166 #define TCP_MAXSEG 2 /* set maximum segment size */
167 #define TCP_NOPUSH 4 /* don't push last block of write */
168 #define TCP_NOOPT 8 /* don't use TCP options */
169 #define TCP_MD5SIG 16 /* use MD5 digests (RFC2385) */
170 #define TCP_INFO 32 /* retrieve tcp_info structure */
171 #define TCP_LOG 34 /* configure event logging for connection */
172 #define TCP_LOGBUF 35 /* retrieve event log for connection */
173 #define TCP_LOGID 36 /* configure log ID to correlate connections */
174 #define TCP_LOGDUMP 37 /* dump connection log events to device */
175 #define TCP_LOGDUMPID 38 /* dump events from connections with same ID to
176  device */
177 #define TCP_TXTLS_ENABLE 39 /* TLS framing and encryption for transmit */
178 #define TCP_TXTLS_MODE 40 /* Transmit TLS mode */
179 #define TCP_CONGESTION 64 /* get/set congestion control algorithm */
180 #define TCP_CCALGOOPT 65 /* get/set cc algorithm specific options */
181 #define TCP_DELACK 72 /* socket option for delayed ack */
182 #define TCP_KEEPINIT 128 /* N, time to establish connection */
183 #define TCP_KEEPIDLE 256 /* L,N,X start keeplives after this period */
184 #define TCP_KEEPINTVL 512 /* L,N interval between keepalives */
185 #define TCP_KEEPCNT 1024 /* L,N number of keepalives before close */
186 #define TCP_FASTOPEN 1025 /* enable TFO / was created via TFO */
187 #define TCP_PCAP_OUT 2048 /* number of output packets to keep */
188 #define TCP_PCAP_IN 4096 /* number of input packets to keep */
189 #define TCP_FUNCTION_BLK 8192 /* Set the tcp function pointers to the specified stack */
190 /* Options for Rack and BBR */
191 #define TCP_RACK_PROP 1051 /* RACK proportional rate reduction (bool) */
192 #define TCP_RACK_TLP_REDUCE 1052 /* RACK TLP cwnd reduction (bool) */
193 #define TCP_RACK_PACE_REDUCE 1053 /* RACK Pacing reduction factor (divisor) */
194 #define TCP_RACK_PACE_MAX_SEG 1054 /* Max segments in a pace */
195 #define TCP_RACK_PACE_ALWAYS 1055 /* Use the always pace method */
196 #define TCP_RACK_PROP_RATE 1056 /* The proportional reduction rate */
197 #define TCP_RACK_PRR_SENDALOT 1057 /* Allow PRR to send more than one seg */
198 #define TCP_RACK_MIN_TO 1058 /* Minimum time between rack t-o's in ms */
199 #define TCP_RACK_EARLY_RECOV 1059 /* Should recovery happen early (bool) */
200 #define TCP_RACK_EARLY_SEG 1060 /* If early recovery max segments */
201 #define TCP_RACK_REORD_THRESH 1061 /* RACK reorder threshold (shift amount) */
202 #define TCP_RACK_REORD_FADE 1062 /* Does reordering fade after ms time */
203 #define TCP_RACK_TLP_THRESH 1063 /* RACK TLP theshold i.e. srtt+(srtt/N) */
204 #define TCP_RACK_PKT_DELAY 1064 /* RACK added ms i.e. rack-rtt + reord + N */
205 #define TCP_RACK_TLP_INC_VAR 1065 /* Does TLP include rtt variance in t-o */
206 #define TCP_BBR_IWINTSO 1067 /* Initial TSO window for BBRs first sends */
207 #define TCP_BBR_RECFORCE 1068 /* Enter recovery force out a segment disregard pacer no longer valid */
208 #define TCP_BBR_STARTUP_PG 1069 /* Startup pacing gain */
209 #define TCP_BBR_DRAIN_PG 1070 /* Drain pacing gain */
210 #define TCP_BBR_RWND_IS_APP 1071 /* Rwnd limited is considered app limited */
211 #define TCP_BBR_PROBE_RTT_INT 1072 /* How long in useconds between probe-rtt */
212 #define TCP_BBR_ONE_RETRAN 1073 /* Is only one segment allowed out during retran */
213 #define TCP_BBR_STARTUP_LOSS_EXIT 1074 /* Do we exit a loss during startup if not 20% incr */
214 #define TCP_BBR_USE_LOWGAIN 1075 /* lower the gain in PROBE_BW enable */
215 #define TCP_BBR_LOWGAIN_THRESH 1076 /* Unused after 2.3 morphs to TSLIMITS >= 2.3 */
216 #define TCP_BBR_TSLIMITS 1076 /* Do we use experimental Timestamp limiting for our algo */
217 #define TCP_BBR_LOWGAIN_HALF 1077 /* Unused after 2.3 */
218 #define TCP_BBR_PACE_OH 1077 /* Reused in 4.2 for pacing overhead setting */
219 #define TCP_BBR_LOWGAIN_FD 1078 /* Unused after 2.3 */
220 #define TCP_BBR_HOLD_TARGET 1078 /* For 4.3 on */
221 #define TCP_BBR_USEDEL_RATE 1079 /* Enable use of delivery rate for loss recovery */
222 #define TCP_BBR_MIN_RTO 1080 /* Min RTO in milliseconds */
223 #define TCP_BBR_MAX_RTO 1081 /* Max RTO in milliseconds */
224 #define TCP_BBR_REC_OVER_HPTS 1082 /* Recovery override htps settings 0/1/3 */
225 #define TCP_BBR_UNLIMITED 1083 /* Not used before 2.3 and morphs to algorithm >= 2.3 */
226 #define TCP_BBR_ALGORITHM 1083 /* What measurement algo does BBR use netflix=0, google=1 */
227 #define TCP_BBR_DRAIN_INC_EXTRA 1084 /* Does the 3/4 drain target include the extra gain */
228 #define TCP_BBR_STARTUP_EXIT_EPOCH 1085 /* what epoch gets us out of startup */
229 #define TCP_BBR_PACE_PER_SEC 1086
230 #define TCP_BBR_PACE_DEL_TAR 1087
231 #define TCP_BBR_PACE_SEG_MAX 1088
232 #define TCP_BBR_PACE_SEG_MIN 1089
233 #define TCP_BBR_PACE_CROSS 1090
234 #define TCP_RACK_IDLE_REDUCE_HIGH 1092 /* Reduce the highest cwnd seen to IW on idle */
235 #define TCP_RACK_MIN_PACE 1093 /* Do we enforce rack min pace time */
236 #define TCP_RACK_MIN_PACE_SEG 1094 /* If so what is the seg threshould */
237 #define TCP_RACK_GP_INCREASE 1094 /* After 4.1 its the GP increase */
238 #define TCP_RACK_TLP_USE 1095
239 #define TCP_BBR_ACK_COMP_ALG 1096 /* Not used */
240 #define TCP_BBR_TMR_PACE_OH 1096 /* Recycled in 4.2 */
241 #define TCP_BBR_EXTRA_GAIN 1097
242 #define TCP_RACK_DO_DETECTION 1097 /* Recycle of extra gain for rack, attack detection */
243 #define TCP_BBR_RACK_RTT_USE 1098 /* what RTT should we use 0, 1, or 2? */
244 #define TCP_BBR_RETRAN_WTSO 1099
245 #define TCP_DATA_AFTER_CLOSE 1100
246 #define TCP_BBR_PROBE_RTT_GAIN 1101
247 #define TCP_BBR_PROBE_RTT_LEN 1102
248 #define TCP_BBR_SEND_IWND_IN_TSO 1103 /* Do we burst out whole iwin size chunks at start? */
249 #define TCP_BBR_USE_RACK_CHEAT 1104 /* Do we use the rack cheat for pacing rxt's */
250 #define TCP_BBR_HDWR_PACE 1105 /* Enable/disable hardware pacing */
251 #define TCP_BBR_UTTER_MAX_TSO 1106 /* Do we enforce an utter max TSO size */
252 #define TCP_BBR_EXTRA_STATE 1107 /* Special exit-persist catch up */
253 #define TCP_BBR_FLOOR_MIN_TSO 1108 /* The min tso size */
254 #define TCP_BBR_MIN_TOPACEOUT 1109 /* Do we suspend pacing until */
255 #define TCP_BBR_TSTMP_RAISES 1110 /* Can a timestamp measurement raise the b/w */
256 #define TCP_BBR_POLICER_DETECT 1111 /* Turn on/off google mode policer detection */
257 
258 
259 /* Start of reserved space for third-party user-settable options. */
260 #define TCP_VENDOR SO_VENDOR
261 
262 #define TCP_CA_NAME_MAX 16 /* max congestion control name length */
263 
264 #define TCPI_OPT_TIMESTAMPS 0x01
265 #define TCPI_OPT_SACK 0x02
266 #define TCPI_OPT_WSCALE 0x04
267 #define TCPI_OPT_ECN 0x08
268 #define TCPI_OPT_TOE 0x10
269 
270 /* Maximum length of log ID. */
271 #define TCP_LOG_ID_LEN 64
272 
273 /*
274  * The TCP_INFO socket option comes from the Linux 2.6 TCP API, and permits
275  * the caller to query certain information about the state of a TCP
276  * connection. We provide an overlapping set of fields with the Linux
277  * implementation, but since this is a fixed size structure, room has been
278  * left for growth. In order to maximize potential future compatibility with
279  * the Linux API, the same variable names and order have been adopted, and
280  * padding left to make room for omitted fields in case they are added later.
281  *
282  * XXX: This is currently an unstable ABI/API, in that it is expected to
283  * change.
284  */
285 struct tcp_info {
286  u_int8_t tcpi_state; /* TCP FSM state. */
287  u_int8_t __tcpi_ca_state;
288  u_int8_t __tcpi_retransmits;
289  u_int8_t __tcpi_probes;
290  u_int8_t __tcpi_backoff;
291  u_int8_t tcpi_options; /* Options enabled on conn. */
292  u_int8_t tcpi_snd_wscale:4, /* RFC1323 send shift value. */
293  tcpi_rcv_wscale:4; /* RFC1323 recv shift value. */
294 
295  u_int32_t tcpi_rto; /* Retransmission timeout (usec). */
296  u_int32_t __tcpi_ato;
297  u_int32_t tcpi_snd_mss; /* Max segment size for send. */
298  u_int32_t tcpi_rcv_mss; /* Max segment size for receive. */
299 
300  u_int32_t __tcpi_unacked;
301  u_int32_t __tcpi_sacked;
302  u_int32_t __tcpi_lost;
303  u_int32_t __tcpi_retrans;
304  u_int32_t __tcpi_fackets;
305 
306  /* Times; measurements in usecs. */
307  u_int32_t __tcpi_last_data_sent;
308  u_int32_t __tcpi_last_ack_sent; /* Also unimpl. on Linux? */
309  u_int32_t tcpi_last_data_recv; /* Time since last recv data. */
310  u_int32_t __tcpi_last_ack_recv;
311 
312  /* Metrics; variable units. */
313  u_int32_t __tcpi_pmtu;
314  u_int32_t __tcpi_rcv_ssthresh;
315  u_int32_t tcpi_rtt; /* Smoothed RTT in usecs. */
316  u_int32_t tcpi_rttvar; /* RTT variance in usecs. */
317  u_int32_t tcpi_snd_ssthresh; /* Slow start threshold. */
318  u_int32_t tcpi_snd_cwnd; /* Send congestion window. */
319  u_int32_t __tcpi_advmss;
320  u_int32_t __tcpi_reordering;
321 
322  u_int32_t __tcpi_rcv_rtt;
323  u_int32_t tcpi_rcv_space; /* Advertised recv window. */
324 
325  /* FreeBSD extensions to tcp_info. */
326  u_int32_t tcpi_snd_wnd; /* Advertised send window. */
327  u_int32_t tcpi_snd_bwnd; /* No longer used. */
328  u_int32_t tcpi_snd_nxt; /* Next egress seqno */
329  u_int32_t tcpi_rcv_nxt; /* Next ingress seqno */
330  u_int32_t tcpi_toe_tid; /* HWTID for TOE endpoints */
331  u_int32_t tcpi_snd_rexmitpack; /* Retransmitted packets */
332  u_int32_t tcpi_rcv_ooopack; /* Out-of-order packets */
333  u_int32_t tcpi_snd_zerowin; /* Zero-sized windows sent */
334 
335  /* Padding to grow without breaking ABI. */
336  u_int32_t __tcpi_pad[26]; /* Padding. */
337 };
338 
339 /*
340  * If this structure is provided when setting the TCP_FASTOPEN socket
341  * option, and the enable member is non-zero, a subsequent connect will use
342  * pre-shared key (PSK) mode using the provided key.
343  */
344 struct tcp_fastopen {
345  int enable;
346  uint8_t psk[TCP_FASTOPEN_PSK_LEN];
347 };
348 #endif
349 #define TCP_FUNCTION_NAME_LEN_MAX 32
350 
354 };
355 
356 /* TLS modes for TCP_TXTLS_MODE */
357 #define TCP_TLS_MODE_NONE 0
358 #define TCP_TLS_MODE_SW 1
359 #define TCP_TLS_MODE_IFNET 2
360 #define TCP_TLS_MODE_TOE 3
361 
362 /*
363  * TCP Control message types
364  */
365 #define TLS_SET_RECORD_TYPE 1
366 
367 #endif /* !_NETINET_TCP_H_ */
char function_set_name[TCP_FUNCTION_NAME_LEN_MAX]
Definition: tcp.h:352
__uint8_t uint8_t
Definition: in.h:52
#define TCP_FUNCTION_NAME_LEN_MAX
Definition: tcp.h:349
uint32_t pcbcnt
Definition: tcp.h:353
__uint32_t uint32_t
Definition: in.h:62