FreeBSD/Linux Kernel Cross Reference
sys/netinet/tcp_var.h
1 /*
2 * Copyright (c) 1982, 1986, 1993, 1994, 1995
3 * The Regents of the University of California. All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. All advertising materials mentioning features or use of this software
14 * must display the following acknowledgement:
15 * This product includes software developed by the University of
16 * California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 * may be used to endorse or promote products derived from this software
19 * without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 *
33 * @(#)tcp_var.h 8.4 (Berkeley) 5/24/95
34 * $FreeBSD: src/sys/netinet/tcp_var.h,v 1.36.2.2 1999/09/05 08:18:46 peter Exp $
35 */
36
37 #ifndef _NETINET_TCP_VAR_H_
38 #define _NETINET_TCP_VAR_H_
39 /*
40 * Kernel variables for tcp.
41 */
42
43 /*
44 * Tcp control block, one per tcp; fields:
45 */
46 struct tcpcb {
47 struct tcpiphdr *seg_next; /* sequencing queue */
48 struct tcpiphdr *seg_prev;
49 int t_state; /* state of this connection */
50 int t_timer[TCPT_NTIMERS]; /* tcp timers */
51 int t_rxtshift; /* log(2) of rexmt exp. backoff */
52 int t_rxtcur; /* current retransmit value */
53 int t_dupacks; /* consecutive dup acks recd */
54 u_int t_maxseg; /* maximum segment size */
55 u_int t_maxopd; /* mss plus options */
56 int t_force; /* 1 if forcing out a byte */
57 u_int t_flags;
58 #define TF_ACKNOW 0x0001 /* ack peer immediately */
59 #define TF_DELACK 0x0002 /* ack, but try to delay it */
60 #define TF_NODELAY 0x0004 /* don't delay packets to coalesce */
61 #define TF_NOOPT 0x0008 /* don't use tcp options */
62 #define TF_SENTFIN 0x0010 /* have sent FIN */
63 #define TF_REQ_SCALE 0x0020 /* have/will request window scaling */
64 #define TF_RCVD_SCALE 0x0040 /* other side has requested scaling */
65 #define TF_REQ_TSTMP 0x0080 /* have/will request timestamps */
66 #define TF_RCVD_TSTMP 0x0100 /* a timestamp was received in SYN */
67 #define TF_SACK_PERMIT 0x0200 /* other side said I could SACK */
68 #define TF_NEEDSYN 0x0400 /* send SYN (implicit state) */
69 #define TF_NEEDFIN 0x0800 /* send FIN (implicit state) */
70 #define TF_NOPUSH 0x1000 /* don't push */
71 #define TF_REQ_CC 0x2000 /* have/will request CC */
72 #define TF_RCVD_CC 0x4000 /* a CC was received in SYN */
73 #define TF_SENDCCNEW 0x8000 /* send CCnew instead of CC in SYN */
74
75 struct tcpiphdr *t_template; /* skeletal packet for transmit */
76 struct inpcb *t_inpcb; /* back pointer to internet pcb */
77 /*
78 * The following fields are used as in the protocol specification.
79 * See RFC783, Dec. 1981, page 21.
80 */
81 /* send sequence variables */
82 tcp_seq snd_una; /* send unacknowledged */
83 tcp_seq snd_nxt; /* send next */
84 tcp_seq snd_up; /* send urgent pointer */
85 tcp_seq snd_wl1; /* window update seg seq number */
86 tcp_seq snd_wl2; /* window update seg ack number */
87 tcp_seq iss; /* initial send sequence number */
88 u_long snd_wnd; /* send window */
89 /* receive sequence variables */
90 u_long rcv_wnd; /* receive window */
91 tcp_seq rcv_nxt; /* receive next */
92 tcp_seq rcv_up; /* receive urgent pointer */
93 tcp_seq irs; /* initial receive sequence number */
94 /*
95 * Additional variables for this implementation.
96 */
97 /* receive variables */
98 tcp_seq rcv_adv; /* advertised window */
99 /* retransmit variables */
100 tcp_seq snd_max; /* highest sequence number sent;
101 * used to recognize retransmits
102 */
103 /* congestion control (for slow start, source quench, retransmit after loss) */
104 u_long snd_cwnd; /* congestion-controlled window */
105 u_long snd_ssthresh; /* snd_cwnd size threshold for
106 * for slow start exponential to
107 * linear switch
108 */
109 /*
110 * transmit timing stuff. See below for scale of srtt and rttvar.
111 * "Variance" is actually smoothed difference.
112 */
113 u_int t_idle; /* inactivity time */
114 int t_rtt; /* round trip time */
115 tcp_seq t_rtseq; /* sequence number being timed */
116 int t_srtt; /* smoothed round-trip time */
117 int t_rttvar; /* variance in round-trip time */
118 u_int t_rttmin; /* minimum rtt allowed */
119 u_long max_sndwnd; /* largest window peer has offered */
120
121 /* out-of-band data */
122 char t_oobflags; /* have some */
123 char t_iobc; /* input character */
124 #define TCPOOB_HAVEDATA 0x01
125 #define TCPOOB_HADDATA 0x02
126 int t_softerror; /* possible error not yet reported */
127
128 /* RFC 1323 variables */
129 u_char snd_scale; /* window scaling for send window */
130 u_char rcv_scale; /* window scaling for recv window */
131 u_char request_r_scale; /* pending window scaling */
132 u_char requested_s_scale;
133 u_long ts_recent; /* timestamp echo data */
134 u_long ts_recent_age; /* when last updated */
135 tcp_seq last_ack_sent;
136 /* RFC 1644 variables */
137 tcp_cc cc_send; /* send connection count */
138 tcp_cc cc_recv; /* receive connection count */
139 u_long t_duration; /* connection duration */
140
141 /* TUBA stuff */
142 caddr_t t_tuba_pcb; /* next level down pcb for TCP over z */
143 /* More RTT stuff */
144 u_long t_rttupdated; /* number of times rtt sampled */
145 };
146
147 /*
148 * Structure to hold TCP options that are only used during segment
149 * processing (in tcp_input), but not held in the tcpcb.
150 * It's basically used to reduce the number of parameters
151 * to tcp_dooptions.
152 */
153 struct tcpopt {
154 u_long to_flag; /* which options are present */
155 #define TOF_TS 0x0001 /* timestamp */
156 #define TOF_CC 0x0002 /* CC and CCnew are exclusive */
157 #define TOF_CCNEW 0x0004
158 #define TOF_CCECHO 0x0008
159 u_long to_tsval;
160 u_long to_tsecr;
161 tcp_cc to_cc; /* holds CC or CCnew */
162 tcp_cc to_ccecho;
163 };
164
165 /*
166 * The TAO cache entry which is stored in the protocol family specific
167 * portion of the route metrics.
168 */
169 struct rmxp_tao {
170 tcp_cc tao_cc; /* latest CC in valid SYN */
171 tcp_cc tao_ccsent; /* latest CC sent to peer */
172 u_short tao_mssopt; /* peer's cached MSS */
173 #ifdef notyet
174 u_short tao_flags; /* cache status flags */
175 #define TAOF_DONT 0x0001 /* peer doesn't understand rfc1644 */
176 #define TAOF_OK 0x0002 /* peer does understand rfc1644 */
177 #define TAOF_UNDEF 0 /* we don't know yet */
178 #endif /* notyet */
179 };
180 #define rmx_taop(r) ((struct rmxp_tao *)(r).rmx_filler)
181
182 #define intotcpcb(ip) ((struct tcpcb *)(ip)->inp_ppcb)
183 #define sototcpcb(so) (intotcpcb(sotoinpcb(so)))
184
185 /*
186 * The smoothed round-trip time and estimated variance
187 * are stored as fixed point numbers scaled by the values below.
188 * For convenience, these scales are also used in smoothing the average
189 * (smoothed = (1/scale)sample + ((scale-1)/scale)smoothed).
190 * With these scales, srtt has 3 bits to the right of the binary point,
191 * and thus an "ALPHA" of 0.875. rttvar has 2 bits to the right of the
192 * binary point, and is smoothed with an ALPHA of 0.75.
193 */
194 #define TCP_RTT_SCALE 32 /* multiplier for srtt; 3 bits frac. */
195 #define TCP_RTT_SHIFT 5 /* shift for srtt; 3 bits frac. */
196 #define TCP_RTTVAR_SCALE 16 /* multiplier for rttvar; 2 bits */
197 #define TCP_RTTVAR_SHIFT 4 /* shift for rttvar; 2 bits */
198 #define TCP_DELTA_SHIFT 2 /* see tcp_input.c */
199
200 /*
201 * The initial retransmission should happen at rtt + 4 * rttvar.
202 * Because of the way we do the smoothing, srtt and rttvar
203 * will each average +1/2 tick of bias. When we compute
204 * the retransmit timer, we want 1/2 tick of rounding and
205 * 1 extra tick because of +-1/2 tick uncertainty in the
206 * firing of the timer. The bias will give us exactly the
207 * 1.5 tick we need. But, because the bias is
208 * statistical, we have to test that we don't drop below
209 * the minimum feasible timer (which is 2 ticks).
210 * This version of the macro adapted from a paper by Lawrence
211 * Brakmo and Larry Peterson which outlines a problem caused
212 * by insufficient precision in the original implementation,
213 * which results in inappropriately large RTO values for very
214 * fast networks.
215 */
216 #define TCP_REXMTVAL(tp) \
217 max((tp)->t_rttmin, (((tp)->t_srtt >> (TCP_RTT_SHIFT - TCP_DELTA_SHIFT)) \
218 + (tp)->t_rttvar) >> TCP_DELTA_SHIFT)
219
220 /* XXX
221 * We want to avoid doing m_pullup on incoming packets but that
222 * means avoiding dtom on the tcp reassembly code. That in turn means
223 * keeping an mbuf pointer in the reassembly queue (since we might
224 * have a cluster). As a quick hack, the source & destination
225 * port numbers (which are no longer needed once we've located the
226 * tcpcb) are overlayed with an mbuf pointer.
227 */
228 #define REASS_MBUF(ti) (*(struct mbuf **)&((ti)->ti_t))
229
230 /*
231 * TCP statistics.
232 * Many of these should be kept per connection,
233 * but that's inconvenient at the moment.
234 */
235 struct tcpstat {
236 u_long tcps_connattempt; /* connections initiated */
237 u_long tcps_accepts; /* connections accepted */
238 u_long tcps_connects; /* connections established */
239 u_long tcps_drops; /* connections dropped */
240 u_long tcps_conndrops; /* embryonic connections dropped */
241 u_long tcps_closed; /* conn. closed (includes drops) */
242 u_long tcps_segstimed; /* segs where we tried to get rtt */
243 u_long tcps_rttupdated; /* times we succeeded */
244 u_long tcps_delack; /* delayed acks sent */
245 u_long tcps_timeoutdrop; /* conn. dropped in rxmt timeout */
246 u_long tcps_rexmttimeo; /* retransmit timeouts */
247 u_long tcps_persisttimeo; /* persist timeouts */
248 u_long tcps_keeptimeo; /* keepalive timeouts */
249 u_long tcps_keepprobe; /* keepalive probes sent */
250 u_long tcps_keepdrops; /* connections dropped in keepalive */
251
252 u_long tcps_sndtotal; /* total packets sent */
253 u_long tcps_sndpack; /* data packets sent */
254 u_long tcps_sndbyte; /* data bytes sent */
255 u_long tcps_sndrexmitpack; /* data packets retransmitted */
256 u_long tcps_sndrexmitbyte; /* data bytes retransmitted */
257 u_long tcps_sndacks; /* ack-only packets sent */
258 u_long tcps_sndprobe; /* window probes sent */
259 u_long tcps_sndurg; /* packets sent with URG only */
260 u_long tcps_sndwinup; /* window update-only packets sent */
261 u_long tcps_sndctrl; /* control (SYN|FIN|RST) packets sent */
262
263 u_long tcps_rcvtotal; /* total packets received */
264 u_long tcps_rcvpack; /* packets received in sequence */
265 u_long tcps_rcvbyte; /* bytes received in sequence */
266 u_long tcps_rcvbadsum; /* packets received with ccksum errs */
267 u_long tcps_rcvbadoff; /* packets received with bad offset */
268 u_long tcps_rcvshort; /* packets received too short */
269 u_long tcps_rcvduppack; /* duplicate-only packets received */
270 u_long tcps_rcvdupbyte; /* duplicate-only bytes received */
271 u_long tcps_rcvpartduppack; /* packets with some duplicate data */
272 u_long tcps_rcvpartdupbyte; /* dup. bytes in part-dup. packets */
273 u_long tcps_rcvoopack; /* out-of-order packets received */
274 u_long tcps_rcvoobyte; /* out-of-order bytes received */
275 u_long tcps_rcvpackafterwin; /* packets with data after window */
276 u_long tcps_rcvbyteafterwin; /* bytes rcvd after window */
277 u_long tcps_rcvafterclose; /* packets rcvd after "close" */
278 u_long tcps_rcvwinprobe; /* rcvd window probe packets */
279 u_long tcps_rcvdupack; /* rcvd duplicate acks */
280 u_long tcps_rcvacktoomuch; /* rcvd acks for unsent data */
281 u_long tcps_rcvackpack; /* rcvd ack packets */
282 u_long tcps_rcvackbyte; /* bytes acked by rcvd acks */
283 u_long tcps_rcvwinupd; /* rcvd window update packets */
284 u_long tcps_pawsdrop; /* segments dropped due to PAWS */
285 u_long tcps_predack; /* times hdr predict ok for acks */
286 u_long tcps_preddat; /* times hdr predict ok for data pkts */
287 u_long tcps_pcbcachemiss;
288 u_long tcps_cachedrtt; /* times cached RTT in route updated */
289 u_long tcps_cachedrttvar; /* times cached rttvar updated */
290 u_long tcps_cachedssthresh; /* times cached ssthresh updated */
291 u_long tcps_usedrtt; /* times RTT initialized from route */
292 u_long tcps_usedrttvar; /* times RTTVAR initialized from rt */
293 u_long tcps_usedssthresh; /* times ssthresh initialized from rt*/
294 u_long tcps_persistdrop; /* timeout in persist state */
295 u_long tcps_badsyn; /* bogus SYN, e.g. premature ACK */
296 u_long tcps_mturesent; /* resends due to MTU discovery */
297 u_long tcps_listendrop; /* listen queue overflows */
298 };
299
300 /*
301 * Names for TCP sysctl objects
302 */
303 #define TCPCTL_DO_RFC1323 1 /* use RFC-1323 extensions */
304 #define TCPCTL_DO_RFC1644 2 /* use RFC-1644 extensions */
305 #define TCPCTL_MSSDFLT 3 /* MSS default */
306 #define TCPCTL_STATS 4 /* statistics (read-only) */
307 #define TCPCTL_RTTDFLT 5 /* default RTT estimate */
308 #define TCPCTL_KEEPIDLE 6 /* keepalive idle timer */
309 #define TCPCTL_KEEPINTVL 7 /* interval to send keepalives */
310 #define TCPCTL_SENDSPACE 8 /* send buffer space */
311 #define TCPCTL_RECVSPACE 9 /* receive buffer space */
312 #define TCPCTL_KEEPINIT 10 /* receive buffer space */
313 #define TCPCTL_MAXID 11
314
315 #define TCPCTL_NAMES { \
316 { 0, 0 }, \
317 { "rfc1323", CTLTYPE_INT }, \
318 { "rfc1644", CTLTYPE_INT }, \
319 { "mssdflt", CTLTYPE_INT }, \
320 { "stats", CTLTYPE_STRUCT }, \
321 { "rttdflt", CTLTYPE_INT }, \
322 { "keepidle", CTLTYPE_INT }, \
323 { "keepintvl", CTLTYPE_INT }, \
324 { "sendspace", CTLTYPE_INT }, \
325 { "recvspace", CTLTYPE_INT }, \
326 { "keepinit", CTLTYPE_INT }, \
327 }
328
329 #ifdef KERNEL
330 extern struct inpcbhead tcb; /* head of queue of active tcpcb's */
331 extern struct inpcbinfo tcbinfo;
332 extern struct tcpstat tcpstat; /* tcp statistics */
333 extern int tcp_mssdflt; /* XXX */
334 extern u_long tcp_now; /* for RFC 1323 timestamps */
335
336 void tcp_canceltimers __P((struct tcpcb *));
337 struct tcpcb *
338 tcp_close __P((struct tcpcb *));
339 void tcp_ctlinput __P((int, struct sockaddr *, void *));
340 int tcp_ctloutput __P((int, struct socket *, int, int, struct mbuf **));
341 struct tcpcb *
342 tcp_drop __P((struct tcpcb *, int));
343 void tcp_drain __P((void));
344 void tcp_fasttimo __P((void));
345 struct rmxp_tao *
346 tcp_gettaocache __P((struct inpcb *));
347 void tcp_init __P((void));
348 void tcp_input __P((struct mbuf *, int));
349 void tcp_mss __P((struct tcpcb *, int));
350 int tcp_mssopt __P((struct tcpcb *));
351 void tcp_mtudisc __P((struct inpcb *, int));
352 struct tcpcb *
353 tcp_newtcpcb __P((struct inpcb *));
354 int tcp_output __P((struct tcpcb *));
355 void tcp_quench __P((struct inpcb *, int));
356 void tcp_respond __P((struct tcpcb *,
357 struct tcpiphdr *, struct mbuf *, u_long, u_long, int));
358 struct rtentry *
359 tcp_rtlookup __P((struct inpcb *));
360 void tcp_setpersist __P((struct tcpcb *));
361 void tcp_slowtimo __P((void));
362 struct tcpiphdr *
363 tcp_template __P((struct tcpcb *));
364 struct tcpcb *
365 tcp_timers __P((struct tcpcb *, int));
366 void tcp_trace __P((int, int, struct tcpcb *, struct tcpiphdr *, int));
367
368 extern struct pr_usrreqs tcp_usrreqs;
369 extern u_long tcp_sendspace;
370 extern u_long tcp_recvspace;
371
372 #endif /* KERNEL */
373
374 #endif /* _NETINET_TCP_VAR_H_ */
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