tcp_subr.c revision 1.37 1 /* $NetBSD: tcp_subr.c,v 1.37 1997/12/31 03:31:26 thorpej Exp $ */
2
3 /*
4 * Copyright (c) 1982, 1986, 1988, 1990, 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. All advertising materials mentioning features or use of this software
16 * must display the following acknowledgement:
17 * This product includes software developed by the University of
18 * California, Berkeley and its contributors.
19 * 4. Neither the name of the University nor the names of its contributors
20 * may be used to endorse or promote products derived from this software
21 * without specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
34 *
35 * @(#)tcp_subr.c 8.1 (Berkeley) 6/10/93
36 */
37
38 #include "rnd.h"
39
40 #include <sys/param.h>
41 #include <sys/proc.h>
42 #include <sys/systm.h>
43 #include <sys/malloc.h>
44 #include <sys/mbuf.h>
45 #include <sys/socket.h>
46 #include <sys/socketvar.h>
47 #include <sys/protosw.h>
48 #include <sys/errno.h>
49 #include <sys/kernel.h>
50 #if NRND > 0
51 #include <sys/rnd.h>
52 #endif
53
54 #include <net/route.h>
55 #include <net/if.h>
56
57 #include <netinet/in.h>
58 #include <netinet/in_systm.h>
59 #include <netinet/ip.h>
60 #include <netinet/in_pcb.h>
61 #include <netinet/ip_var.h>
62 #include <netinet/ip_icmp.h>
63 #include <netinet/tcp.h>
64 #include <netinet/tcp_fsm.h>
65 #include <netinet/tcp_seq.h>
66 #include <netinet/tcp_timer.h>
67 #include <netinet/tcp_var.h>
68 #include <netinet/tcpip.h>
69
70 /* patchable/settable parameters for tcp */
71 int tcp_mssdflt = TCP_MSS;
72 int tcp_rttdflt = TCPTV_SRTTDFLT / PR_SLOWHZ;
73 int tcp_do_rfc1323 = 1;
74 int tcp_init_win = 1;
75
76 #ifndef TCBHASHSIZE
77 #define TCBHASHSIZE 128
78 #endif
79 int tcbhashsize = TCBHASHSIZE;
80
81 int tcp_freeq __P((struct tcpcb *));
82
83 /*
84 * Tcp initialization
85 */
86 void
87 tcp_init()
88 {
89
90 in_pcbinit(&tcbtable, tcbhashsize, tcbhashsize);
91 LIST_INIT(&tcp_delacks);
92 if (max_protohdr < sizeof(struct tcpiphdr))
93 max_protohdr = sizeof(struct tcpiphdr);
94 if (max_linkhdr + sizeof(struct tcpiphdr) > MHLEN)
95 panic("tcp_init");
96 }
97
98 /*
99 * Create template to be used to send tcp packets on a connection.
100 * Call after host entry created, allocates an mbuf and fills
101 * in a skeletal tcp/ip header, minimizing the amount of work
102 * necessary when the connection is used.
103 */
104 struct tcpiphdr *
105 tcp_template(tp)
106 struct tcpcb *tp;
107 {
108 register struct inpcb *inp = tp->t_inpcb;
109 register struct tcpiphdr *n;
110
111 if ((n = tp->t_template) == 0) {
112 MALLOC(n, struct tcpiphdr *, sizeof (struct tcpiphdr),
113 M_MBUF, M_NOWAIT);
114 if (n == NULL)
115 return (0);
116 }
117 bzero(n->ti_x1, sizeof n->ti_x1);
118 n->ti_pr = IPPROTO_TCP;
119 n->ti_len = htons(sizeof (struct tcpiphdr) - sizeof (struct ip));
120 n->ti_src = inp->inp_laddr;
121 n->ti_dst = inp->inp_faddr;
122 n->ti_sport = inp->inp_lport;
123 n->ti_dport = inp->inp_fport;
124 n->ti_seq = 0;
125 n->ti_ack = 0;
126 n->ti_x2 = 0;
127 n->ti_off = 5;
128 n->ti_flags = 0;
129 n->ti_win = 0;
130 n->ti_sum = 0;
131 n->ti_urp = 0;
132 return (n);
133 }
134
135 /*
136 * Send a single message to the TCP at address specified by
137 * the given TCP/IP header. If m == 0, then we make a copy
138 * of the tcpiphdr at ti and send directly to the addressed host.
139 * This is used to force keep alive messages out using the TCP
140 * template for a connection tp->t_template. If flags are given
141 * then we send a message back to the TCP which originated the
142 * segment ti, and discard the mbuf containing it and any other
143 * attached mbufs.
144 *
145 * In any case the ack and sequence number of the transmitted
146 * segment are as specified by the parameters.
147 */
148 int
149 tcp_respond(tp, ti, m, ack, seq, flags)
150 struct tcpcb *tp;
151 register struct tcpiphdr *ti;
152 register struct mbuf *m;
153 tcp_seq ack, seq;
154 int flags;
155 {
156 register int tlen;
157 int win = 0;
158 struct route *ro = 0;
159
160 if (tp) {
161 win = sbspace(&tp->t_inpcb->inp_socket->so_rcv);
162 ro = &tp->t_inpcb->inp_route;
163 }
164 if (m == 0) {
165 m = m_gethdr(M_DONTWAIT, MT_HEADER);
166 if (m == NULL)
167 return (ENOBUFS);
168 #ifdef TCP_COMPAT_42
169 tlen = 1;
170 #else
171 tlen = 0;
172 #endif
173 m->m_data += max_linkhdr;
174 *mtod(m, struct tcpiphdr *) = *ti;
175 ti = mtod(m, struct tcpiphdr *);
176 flags = TH_ACK;
177 } else {
178 m_freem(m->m_next);
179 m->m_next = 0;
180 m->m_data = (caddr_t)ti;
181 m->m_len = sizeof (struct tcpiphdr);
182 tlen = 0;
183 #define xchg(a,b,type) { type t; t=a; a=b; b=t; }
184 xchg(ti->ti_dst.s_addr, ti->ti_src.s_addr, u_int32_t);
185 xchg(ti->ti_dport, ti->ti_sport, u_int16_t);
186 #undef xchg
187 }
188 bzero(ti->ti_x1, sizeof ti->ti_x1);
189 ti->ti_seq = htonl(seq);
190 ti->ti_ack = htonl(ack);
191 ti->ti_x2 = 0;
192 if ((flags & TH_SYN) == 0) {
193 if (tp)
194 ti->ti_win = htons((u_int16_t) (win >> tp->rcv_scale));
195 else
196 ti->ti_win = htons((u_int16_t)win);
197 ti->ti_off = sizeof (struct tcphdr) >> 2;
198 tlen += sizeof (struct tcphdr);
199 } else
200 tlen += ti->ti_off << 2;
201 ti->ti_len = htons((u_int16_t)tlen);
202 tlen += sizeof (struct ip);
203 m->m_len = tlen;
204 m->m_pkthdr.len = tlen;
205 m->m_pkthdr.rcvif = (struct ifnet *) 0;
206 ti->ti_flags = flags;
207 ti->ti_urp = 0;
208 ti->ti_sum = 0;
209 ti->ti_sum = in_cksum(m, tlen);
210 ((struct ip *)ti)->ip_len = tlen;
211 ((struct ip *)ti)->ip_ttl = ip_defttl;
212 return ip_output(m, NULL, ro, 0, NULL);
213 }
214
215 /*
216 * Create a new TCP control block, making an
217 * empty reassembly queue and hooking it to the argument
218 * protocol control block.
219 */
220 struct tcpcb *
221 tcp_newtcpcb(inp)
222 struct inpcb *inp;
223 {
224 register struct tcpcb *tp;
225
226 tp = malloc(sizeof(*tp), M_PCB, M_NOWAIT);
227 if (tp == NULL)
228 return ((struct tcpcb *)0);
229 bzero((caddr_t)tp, sizeof(struct tcpcb));
230 LIST_INIT(&tp->segq);
231 tp->t_peermss = tcp_mssdflt;
232 tp->t_ourmss = tcp_mssdflt;
233 tp->t_segsz = tcp_mssdflt;
234
235 tp->t_flags = tcp_do_rfc1323 ? (TF_REQ_SCALE|TF_REQ_TSTMP) : 0;
236 tp->t_inpcb = inp;
237 /*
238 * Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no
239 * rtt estimate. Set rttvar so that srtt + 2 * rttvar gives
240 * reasonable initial retransmit time.
241 */
242 tp->t_srtt = TCPTV_SRTTBASE;
243 tp->t_rttvar = tcp_rttdflt * PR_SLOWHZ << (TCP_RTTVAR_SHIFT + 2 - 1);
244 tp->t_rttmin = TCPTV_MIN;
245 TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp),
246 TCPTV_MIN, TCPTV_REXMTMAX);
247 tp->snd_cwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT;
248 tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT;
249 inp->inp_ip.ip_ttl = ip_defttl;
250 inp->inp_ppcb = (caddr_t)tp;
251 return (tp);
252 }
253
254 /*
255 * Drop a TCP connection, reporting
256 * the specified error. If connection is synchronized,
257 * then send a RST to peer.
258 */
259 struct tcpcb *
260 tcp_drop(tp, errno)
261 register struct tcpcb *tp;
262 int errno;
263 {
264 struct socket *so = tp->t_inpcb->inp_socket;
265
266 if (TCPS_HAVERCVDSYN(tp->t_state)) {
267 tp->t_state = TCPS_CLOSED;
268 (void) tcp_output(tp);
269 tcpstat.tcps_drops++;
270 } else
271 tcpstat.tcps_conndrops++;
272 if (errno == ETIMEDOUT && tp->t_softerror)
273 errno = tp->t_softerror;
274 so->so_error = errno;
275 return (tcp_close(tp));
276 }
277
278 /*
279 * Close a TCP control block:
280 * discard all space held by the tcp
281 * discard internet protocol block
282 * wake up any sleepers
283 */
284 struct tcpcb *
285 tcp_close(tp)
286 register struct tcpcb *tp;
287 {
288 struct inpcb *inp = tp->t_inpcb;
289 struct socket *so = inp->inp_socket;
290 #ifdef RTV_RTT
291 register struct rtentry *rt;
292
293 /*
294 * If we sent enough data to get some meaningful characteristics,
295 * save them in the routing entry. 'Enough' is arbitrarily
296 * defined as the sendpipesize (default 4K) * 16. This would
297 * give us 16 rtt samples assuming we only get one sample per
298 * window (the usual case on a long haul net). 16 samples is
299 * enough for the srtt filter to converge to within 5% of the correct
300 * value; fewer samples and we could save a very bogus rtt.
301 *
302 * Don't update the default route's characteristics and don't
303 * update anything that the user "locked".
304 */
305 if (SEQ_LT(tp->iss + so->so_snd.sb_hiwat * 16, tp->snd_max) &&
306 (rt = inp->inp_route.ro_rt) &&
307 !in_nullhost(satosin(rt_key(rt))->sin_addr)) {
308 register u_long i = 0;
309
310 if ((rt->rt_rmx.rmx_locks & RTV_RTT) == 0) {
311 i = tp->t_srtt *
312 ((RTM_RTTUNIT / PR_SLOWHZ) >> (TCP_RTT_SHIFT + 2));
313 if (rt->rt_rmx.rmx_rtt && i)
314 /*
315 * filter this update to half the old & half
316 * the new values, converting scale.
317 * See route.h and tcp_var.h for a
318 * description of the scaling constants.
319 */
320 rt->rt_rmx.rmx_rtt =
321 (rt->rt_rmx.rmx_rtt + i) / 2;
322 else
323 rt->rt_rmx.rmx_rtt = i;
324 }
325 if ((rt->rt_rmx.rmx_locks & RTV_RTTVAR) == 0) {
326 i = tp->t_rttvar *
327 ((RTM_RTTUNIT / PR_SLOWHZ) >> (TCP_RTTVAR_SHIFT + 2));
328 if (rt->rt_rmx.rmx_rttvar && i)
329 rt->rt_rmx.rmx_rttvar =
330 (rt->rt_rmx.rmx_rttvar + i) / 2;
331 else
332 rt->rt_rmx.rmx_rttvar = i;
333 }
334 /*
335 * update the pipelimit (ssthresh) if it has been updated
336 * already or if a pipesize was specified & the threshhold
337 * got below half the pipesize. I.e., wait for bad news
338 * before we start updating, then update on both good
339 * and bad news.
340 */
341 if (((rt->rt_rmx.rmx_locks & RTV_SSTHRESH) == 0 &&
342 (i = tp->snd_ssthresh) && rt->rt_rmx.rmx_ssthresh) ||
343 i < (rt->rt_rmx.rmx_sendpipe / 2)) {
344 /*
345 * convert the limit from user data bytes to
346 * packets then to packet data bytes.
347 */
348 i = (i + tp->t_segsz / 2) / tp->t_segsz;
349 if (i < 2)
350 i = 2;
351 i *= (u_long)(tp->t_segsz + sizeof (struct tcpiphdr));
352 if (rt->rt_rmx.rmx_ssthresh)
353 rt->rt_rmx.rmx_ssthresh =
354 (rt->rt_rmx.rmx_ssthresh + i) / 2;
355 else
356 rt->rt_rmx.rmx_ssthresh = i;
357 }
358 }
359 #endif /* RTV_RTT */
360 /* free the reassembly queue, if any */
361 (void) tcp_freeq(tp);
362
363 if (tp->t_template)
364 FREE(tp->t_template, M_MBUF);
365 free(tp, M_PCB);
366 inp->inp_ppcb = 0;
367 soisdisconnected(so);
368 in_pcbdetach(inp);
369 tcpstat.tcps_closed++;
370 return ((struct tcpcb *)0);
371 }
372
373 int
374 tcp_freeq(tp)
375 struct tcpcb *tp;
376 {
377 register struct ipqent *qe;
378 int rv = 0;
379
380 while ((qe = tp->segq.lh_first) != NULL) {
381 LIST_REMOVE(qe, ipqe_q);
382 m_freem(qe->ipqe_m);
383 FREE(qe, M_IPQ);
384 rv = 1;
385 }
386 return (rv);
387 }
388
389 /*
390 * Protocol drain routine. Called when memory is in short supply.
391 */
392 void
393 tcp_drain()
394 {
395 register struct inpcb *inp;
396 register struct tcpcb *tp;
397
398 /*
399 * Free the sequence queue of all TCP connections.
400 */
401 inp = tcbtable.inpt_queue.cqh_first;
402 if (inp) /* XXX */
403 for (; inp != (struct inpcb *)&tcbtable.inpt_queue;
404 inp = inp->inp_queue.cqe_next) {
405 if ((tp = intotcpcb(inp)) != NULL) {
406 if (tcp_freeq(tp))
407 tcpstat.tcps_connsdrained++;
408 }
409 }
410 }
411
412 /*
413 * Notify a tcp user of an asynchronous error;
414 * store error as soft error, but wake up user
415 * (for now, won't do anything until can select for soft error).
416 */
417 void
418 tcp_notify(inp, error)
419 struct inpcb *inp;
420 int error;
421 {
422 register struct tcpcb *tp = (struct tcpcb *)inp->inp_ppcb;
423 register struct socket *so = inp->inp_socket;
424
425 /*
426 * Ignore some errors if we are hooked up.
427 * If connection hasn't completed, has retransmitted several times,
428 * and receives a second error, give up now. This is better
429 * than waiting a long time to establish a connection that
430 * can never complete.
431 */
432 if (tp->t_state == TCPS_ESTABLISHED &&
433 (error == EHOSTUNREACH || error == ENETUNREACH ||
434 error == EHOSTDOWN)) {
435 return;
436 } else if (TCPS_HAVEESTABLISHED(tp->t_state) == 0 &&
437 tp->t_rxtshift > 3 && tp->t_softerror)
438 so->so_error = error;
439 else
440 tp->t_softerror = error;
441 wakeup((caddr_t) &so->so_timeo);
442 sorwakeup(so);
443 sowwakeup(so);
444 }
445
446 void *
447 tcp_ctlinput(cmd, sa, v)
448 int cmd;
449 struct sockaddr *sa;
450 register void *v;
451 {
452 register struct ip *ip = v;
453 register struct tcphdr *th;
454 extern int inetctlerrmap[];
455 void (*notify) __P((struct inpcb *, int)) = tcp_notify;
456 int errno;
457 int nmatch;
458
459 if ((unsigned)cmd >= PRC_NCMDS)
460 return NULL;
461 errno = inetctlerrmap[cmd];
462 if (cmd == PRC_QUENCH)
463 notify = tcp_quench;
464 else if (PRC_IS_REDIRECT(cmd))
465 notify = in_rtchange, ip = 0;
466 else if (cmd == PRC_MSGSIZE && ip_mtudisc)
467 notify = tcp_mtudisc, ip = 0;
468 else if (cmd == PRC_HOSTDEAD)
469 ip = 0;
470 else if (errno == 0)
471 return NULL;
472 if (ip) {
473 th = (struct tcphdr *)((caddr_t)ip + (ip->ip_hl << 2));
474 nmatch = in_pcbnotify(&tcbtable, satosin(sa)->sin_addr,
475 th->th_dport, ip->ip_src, th->th_sport, errno, notify);
476 if (nmatch == 0 && syn_cache_count &&
477 (inetctlerrmap[cmd] == EHOSTUNREACH ||
478 inetctlerrmap[cmd] == ENETUNREACH ||
479 inetctlerrmap[cmd] == EHOSTDOWN))
480 syn_cache_unreach(ip, th);
481 } else
482 (void)in_pcbnotifyall(&tcbtable, satosin(sa)->sin_addr, errno,
483 notify);
484 return NULL;
485 }
486
487 /*
488 * When a source quench is received, close congestion window
489 * to one segment. We will gradually open it again as we proceed.
490 */
491 void
492 tcp_quench(inp, errno)
493 struct inpcb *inp;
494 int errno;
495 {
496 struct tcpcb *tp = intotcpcb(inp);
497
498 if (tp)
499 tp->snd_cwnd = tp->t_segsz;
500 }
501
502 /*
503 * On receipt of path MTU corrections, flush old route and replace it
504 * with the new one. Retransmit all unacknowledged packets, to ensure
505 * that all packets will be received.
506 */
507 void
508 tcp_mtudisc(inp, errno)
509 struct inpcb *inp;
510 int errno;
511 {
512 struct tcpcb *tp = intotcpcb(inp);
513 struct rtentry *rt = in_pcbrtentry(inp);
514
515 if (tp != 0) {
516 if (rt != 0) {
517 /*
518 * If this was not a host route, remove and realloc.
519 */
520 if ((rt->rt_flags & RTF_HOST) == 0) {
521 in_rtchange(inp, errno);
522 if ((rt = in_pcbrtentry(inp)) == 0)
523 return;
524 }
525
526 /*
527 * Slow start out of the error condition. We
528 * use the MTU because we know it's smaller
529 * than the previously transmitted segment.
530 */
531 if (rt->rt_rmx.rmx_mtu != 0)
532 tp->snd_cwnd =
533 TCP_INITIAL_WINDOW(rt->rt_rmx.rmx_mtu);
534 }
535
536 /*
537 * Resend unacknowledged packets.
538 */
539 tp->snd_nxt = tp->snd_una;
540 tcp_output(tp);
541 }
542 }
543
544
545 /*
546 * Compute the MSS to advertise to the peer. Called only during
547 * the 3-way handshake. If we are the server (peer initiated
548 * connection), we are called with the TCPCB for the listen
549 * socket. If we are the client (we initiated connection), we
550 * are called witht he TCPCB for the actual connection.
551 */
552 int
553 tcp_mss_to_advertise(tp)
554 const struct tcpcb *tp;
555 {
556 extern u_long in_maxmtu;
557 struct inpcb *inp;
558 struct socket *so;
559 int mss;
560
561 inp = tp->t_inpcb;
562 so = inp->inp_socket;
563
564 /*
565 * In order to avoid defeating path MTU discovery on the peer,
566 * we advertise the max MTU of all attached networks as our MSS,
567 * per RFC 1191, section 3.1.
568 *
569 * XXX Should we allow room for the timestamp option if
570 * XXX rfc1323 is enabled?
571 */
572 mss = in_maxmtu - sizeof(struct tcpiphdr);
573
574 return (mss);
575 }
576
577 /*
578 * Set connection variables based on the peer's advertised MSS.
579 * We are passed the TCPCB for the actual connection. If we
580 * are the server, we are called by the compressed state engine
581 * when the 3-way handshake is complete. If we are the client,
582 * we are called when we recieve the SYN,ACK from the server.
583 *
584 * NOTE: Our advertised MSS value must be initialized in the TCPCB
585 * before this routine is called!
586 */
587 void
588 tcp_mss_from_peer(tp, offer)
589 struct tcpcb *tp;
590 int offer;
591 {
592 struct inpcb *inp = tp->t_inpcb;
593 struct socket *so = inp->inp_socket;
594 #if defined(RTV_SPIPE) || defined(RTV_SSTHRESH)
595 struct rtentry *rt = in_pcbrtentry(inp);
596 #endif
597 u_long bufsize;
598 int mss;
599
600 /*
601 * Assume our MSS is the MSS of the peer, unless they sent us
602 * an offer. Do not accept offers less than 32 bytes.
603 */
604 mss = tp->t_ourmss;
605 if (offer)
606 mss = offer;
607 mss = max(mss, 32); /* sanity */
608
609 /*
610 * If there's a pipesize, change the socket buffer to that size.
611 * Make the socket buffer an integral number of MSS units. If
612 * the MSS is larger than the socket buffer, artificially decrease
613 * the MSS.
614 */
615 #ifdef RTV_SPIPE
616 if (rt != NULL && rt->rt_rmx.rmx_sendpipe != 0)
617 bufsize = rt->rt_rmx.rmx_sendpipe;
618 else
619 #endif
620 bufsize = so->so_snd.sb_hiwat;
621 if (bufsize < mss)
622 mss = bufsize;
623 else {
624 bufsize = roundup(bufsize, mss);
625 if (bufsize > sb_max)
626 bufsize = sb_max;
627 (void) sbreserve(&so->so_snd, bufsize);
628 }
629 tp->t_peermss = mss;
630 tp->t_segsz = mss;
631
632 /* Initialize the initial congestion window. */
633 tp->snd_cwnd = TCP_INITIAL_WINDOW(mss);
634
635 #ifdef RTV_SSTHRESH
636 if (rt != NULL && rt->rt_rmx.rmx_ssthresh) {
637 /*
638 * There's some sort of gateway or interface buffer
639 * limit on the path. Use this to set the slow
640 * start threshold, but set the threshold to no less
641 * than 2 * MSS.
642 */
643 tp->snd_ssthresh = max(2 * mss, rt->rt_rmx.rmx_ssthresh);
644 }
645 #endif
646 }
647
648 /*
649 * Processing necessary when a TCP connection is established.
650 */
651 void
652 tcp_established(tp)
653 struct tcpcb *tp;
654 {
655 struct inpcb *inp = tp->t_inpcb;
656 struct socket *so = inp->inp_socket;
657 #ifdef RTV_RPIPE
658 struct rtentry *rt = in_pcbrtentry(inp);
659 #endif
660 u_long bufsize;
661
662 tp->t_state = TCPS_ESTABLISHED;
663 tp->t_timer[TCPT_KEEP] = tcp_keepidle;
664
665 #ifdef RTV_RPIPE
666 if (rt != NULL && rt->rt_rmx.rmx_recvpipe != 0)
667 bufsize = rt->rt_rmx.rmx_recvpipe;
668 else
669 #endif
670 bufsize = so->so_rcv.sb_hiwat;
671 if (bufsize > tp->t_ourmss) {
672 bufsize = roundup(bufsize, tp->t_ourmss);
673 if (bufsize > sb_max)
674 bufsize = sb_max;
675 (void) sbreserve(&so->so_rcv, bufsize);
676 }
677 }
678
679 /*
680 * Check if there's an initial rtt or rttvar. Convert from the
681 * route-table units to scaled multiples of the slow timeout timer.
682 * Called only during the 3-way handshake.
683 */
684 void
685 tcp_rmx_rtt(tp)
686 struct tcpcb *tp;
687 {
688 #ifdef RTV_RTT
689 struct rtentry *rt;
690 int rtt;
691
692 if ((rt = in_pcbrtentry(tp->t_inpcb)) == NULL)
693 return;
694
695 if (tp->t_srtt == 0 && (rtt = rt->rt_rmx.rmx_rtt)) {
696 /*
697 * XXX The lock bit for MTU indicates that the value
698 * is also a minimum value; this is subject to time.
699 */
700 if (rt->rt_rmx.rmx_locks & RTV_RTT)
701 tp->t_rttmin = rtt / (RTM_RTTUNIT / PR_SLOWHZ);
702 tp->t_srtt = rtt /
703 ((RTM_RTTUNIT / PR_SLOWHZ) >> (TCP_RTT_SHIFT + 2));
704 if (rt->rt_rmx.rmx_rttvar) {
705 tp->t_rttvar = rt->rt_rmx.rmx_rttvar /
706 ((RTM_RTTUNIT / PR_SLOWHZ) >>
707 (TCP_RTTVAR_SHIFT + 2));
708 } else {
709 /* Default variation is +- 1 rtt */
710 tp->t_rttvar =
711 tp->t_srtt >> (TCP_RTT_SHIFT - TCP_RTTVAR_SHIFT);
712 }
713 TCPT_RANGESET(tp->t_rxtcur,
714 ((tp->t_srtt >> 2) + tp->t_rttvar) >> (1 + 2),
715 tp->t_rttmin, TCPTV_REXMTMAX);
716 }
717 #endif
718 }
719
720 tcp_seq tcp_iss_seq = 0; /* tcp initial seq # */
721
722 /*
723 * Get a new sequence value given a tcp control block
724 */
725 tcp_seq
726 tcp_new_iss(tp, len, addin)
727 void *tp;
728 u_long len;
729 tcp_seq addin;
730 {
731 tcp_seq tcp_iss;
732
733 /*
734 * add randomness about this connection, but do not estimate
735 * entropy from the timing, since the physical device driver would
736 * have done that for us.
737 */
738 #if NRND > 0
739 if (tp != NULL)
740 rnd_add_data(NULL, tp, len, 0);
741 #endif
742
743 /*
744 * randomize.
745 */
746 #if NRND > 0
747 rnd_extract_data(&tcp_iss, sizeof(tcp_iss), RND_EXTRACT_ANY);
748 #else
749 tcp_iss = random();
750 #endif
751
752 /*
753 * If we were asked to add some amount to a known value,
754 * we will take a random value obtained above, mask off the upper
755 * bits, and add in the known value. We also add in a constant to
756 * ensure that we are at least a certain distance from the original
757 * value.
758 *
759 * This is used when an old connection is in timed wait
760 * and we have a new one coming in, for instance.
761 */
762 if (addin != 0) {
763 #ifdef TCPISS_DEBUG
764 printf("Random %08x, ", tcp_iss);
765 #endif
766 tcp_iss &= TCP_ISS_RANDOM_MASK;
767 tcp_iss = tcp_iss + addin + TCP_ISSINCR;
768 tcp_iss_seq += TCP_ISSINCR;
769 tcp_iss += tcp_iss_seq;
770 #ifdef TCPISS_DEBUG
771 printf("Old ISS %08x, ISS %08x\n", addin, tcp_iss);
772 #endif
773 } else {
774 tcp_iss &= TCP_ISS_RANDOM_MASK;
775 tcp_iss_seq += TCP_ISSINCR;
776 tcp_iss += tcp_iss_seq;
777 #ifdef TCPISS_DEBUG
778 printf("ISS %08x\n", tcp_iss);
779 #endif
780 }
781
782 #ifdef TCP_COMPAT_42
783 /*
784 * limit it to the positive range for really old TCP implementations
785 */
786 if ((int)tcp_iss < 0)
787 tcp_iss &= 0x7fffffff; /* XXX */
788 #endif
789
790 return tcp_iss;
791 }
792