1/*-
2 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 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 * 4. Neither the name of the University nor the names of its contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 * @(#)tcp_subr.c 8.2 (Berkeley) 5/24/95
30 */
31
32#include <sys/cdefs.h>
| 1/*-
2 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 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 * 4. Neither the name of the University nor the names of its contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 * @(#)tcp_subr.c 8.2 (Berkeley) 5/24/95
30 */
31
32#include <sys/cdefs.h>
|
152SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, nolocaltimewait, CTLFLAG_RW,
153 &VNET_NAME(nolocaltimewait), 0,
154 "Do not create compressed TCP TIME_WAIT entries for local connections");
155
156void
157tcp_tw_zone_change(void)
158{
159
160 if (maxtcptw == 0)
161 uma_zone_set_max(V_tcptw_zone, tcptw_auto_size());
162}
163
164void
165tcp_tw_init(void)
166{
167
168 V_tcptw_zone = uma_zcreate("tcptw", sizeof(struct tcptw),
169 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
170 TUNABLE_INT_FETCH("net.inet.tcp.maxtcptw", &maxtcptw);
171 if (maxtcptw == 0)
172 uma_zone_set_max(V_tcptw_zone, tcptw_auto_size());
173 else
174 uma_zone_set_max(V_tcptw_zone, maxtcptw);
175 TAILQ_INIT(&V_twq_2msl);
176}
177
178#ifdef VIMAGE
179void
180tcp_tw_destroy(void)
181{
182 struct tcptw *tw;
183
184 INP_INFO_WLOCK(&V_tcbinfo);
185 while((tw = TAILQ_FIRST(&V_twq_2msl)) != NULL)
186 tcp_twclose(tw, 0);
187 INP_INFO_WUNLOCK(&V_tcbinfo);
188
189 uma_zdestroy(V_tcptw_zone);
190}
191#endif
192
193/*
194 * Move a TCP connection into TIME_WAIT state.
195 * tcbinfo is locked.
196 * inp is locked, and is unlocked before returning.
197 */
198void
199tcp_twstart(struct tcpcb *tp)
200{
201 struct tcptw *tw;
202 struct inpcb *inp = tp->t_inpcb;
203 int acknow;
204 struct socket *so;
205
206 INP_INFO_WLOCK_ASSERT(&V_tcbinfo); /* tcp_tw_2msl_reset(). */
207 INP_WLOCK_ASSERT(inp);
208
209 if (V_nolocaltimewait && in_localip(inp->inp_faddr)) {
210 tp = tcp_close(tp);
211 if (tp != NULL)
212 INP_WUNLOCK(inp);
213 return;
214 }
215
216 tw = uma_zalloc(V_tcptw_zone, M_NOWAIT);
217 if (tw == NULL) {
218 tw = tcp_tw_2msl_scan(1);
219 if (tw == NULL) {
220 tp = tcp_close(tp);
221 if (tp != NULL)
222 INP_WUNLOCK(inp);
223 return;
224 }
225 }
226 tw->tw_inpcb = inp;
227
228 /*
229 * Recover last window size sent.
230 */
231 tw->last_win = (tp->rcv_adv - tp->rcv_nxt) >> tp->rcv_scale;
232
233 /*
234 * Set t_recent if timestamps are used on the connection.
235 */
236 if ((tp->t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP|TF_NOOPT)) ==
237 (TF_REQ_TSTMP|TF_RCVD_TSTMP)) {
238 tw->t_recent = tp->ts_recent;
239 tw->ts_offset = tp->ts_offset;
240 } else {
241 tw->t_recent = 0;
242 tw->ts_offset = 0;
243 }
244
245 tw->snd_nxt = tp->snd_nxt;
246 tw->rcv_nxt = tp->rcv_nxt;
247 tw->iss = tp->iss;
248 tw->irs = tp->irs;
249 tw->t_starttime = tp->t_starttime;
250 tw->tw_time = 0;
251
252/* XXX
253 * If this code will
254 * be used for fin-wait-2 state also, then we may need
255 * a ts_recent from the last segment.
256 */
257 acknow = tp->t_flags & TF_ACKNOW;
258
259 /*
260 * First, discard tcpcb state, which includes stopping its timers and
261 * freeing it. tcp_discardcb() used to also release the inpcb, but
262 * that work is now done in the caller.
263 *
264 * Note: soisdisconnected() call used to be made in tcp_discardcb(),
265 * and might not be needed here any longer.
266 */
267 tcp_discardcb(tp);
268 so = inp->inp_socket;
269 soisdisconnected(so);
270 tw->tw_cred = crhold(so->so_cred);
271 SOCK_LOCK(so);
272 tw->tw_so_options = so->so_options;
273 SOCK_UNLOCK(so);
274 if (acknow)
275 tcp_twrespond(tw, TH_ACK);
276 inp->inp_ppcb = tw;
277 inp->inp_flags |= INP_TIMEWAIT;
278 tcp_tw_2msl_reset(tw, 0);
279
280 /*
281 * If the inpcb owns the sole reference to the socket, then we can
282 * detach and free the socket as it is not needed in time wait.
283 */
284 if (inp->inp_flags & INP_SOCKREF) {
285 KASSERT(so->so_state & SS_PROTOREF,
286 ("tcp_twstart: !SS_PROTOREF"));
287 inp->inp_flags &= ~INP_SOCKREF;
288 INP_WUNLOCK(inp);
289 ACCEPT_LOCK();
290 SOCK_LOCK(so);
291 so->so_state &= ~SS_PROTOREF;
292 sofree(so);
293 } else
294 INP_WUNLOCK(inp);
295}
296
297#if 0
298/*
299 * The appromixate rate of ISN increase of Microsoft TCP stacks;
300 * the actual rate is slightly higher due to the addition of
301 * random positive increments.
302 *
303 * Most other new OSes use semi-randomized ISN values, so we
304 * do not need to worry about them.
305 */
306#define MS_ISN_BYTES_PER_SECOND 250000
307
308/*
309 * Determine if the ISN we will generate has advanced beyond the last
310 * sequence number used by the previous connection. If so, indicate
311 * that it is safe to recycle this tw socket by returning 1.
312 */
313int
314tcp_twrecycleable(struct tcptw *tw)
315{
316 tcp_seq new_iss = tw->iss;
317 tcp_seq new_irs = tw->irs;
318
319 INP_INFO_WLOCK_ASSERT(&V_tcbinfo);
320 new_iss += (ticks - tw->t_starttime) * (ISN_BYTES_PER_SECOND / hz);
321 new_irs += (ticks - tw->t_starttime) * (MS_ISN_BYTES_PER_SECOND / hz);
322
323 if (SEQ_GT(new_iss, tw->snd_nxt) && SEQ_GT(new_irs, tw->rcv_nxt))
324 return (1);
325 else
326 return (0);
327}
328#endif
329
330/*
331 * Returns 1 if the TIME_WAIT state was killed and we should start over,
332 * looking for a pcb in the listen state. Returns 0 otherwise.
333 */
334int
335tcp_twcheck(struct inpcb *inp, struct tcpopt *to, struct tcphdr *th,
336 struct mbuf *m, int tlen)
337{
338 struct tcptw *tw;
339 int thflags;
340 tcp_seq seq;
341
342 /* tcbinfo lock required for tcp_twclose(), tcp_tw_2msl_reset(). */
343 INP_INFO_WLOCK_ASSERT(&V_tcbinfo);
344 INP_WLOCK_ASSERT(inp);
345
346 /*
347 * XXXRW: Time wait state for inpcb has been recycled, but inpcb is
348 * still present. This is undesirable, but temporarily necessary
349 * until we work out how to handle inpcb's who's timewait state has
350 * been removed.
351 */
352 tw = intotw(inp);
353 if (tw == NULL)
354 goto drop;
355
356 thflags = th->th_flags;
357
358 /*
359 * NOTE: for FIN_WAIT_2 (to be added later),
360 * must validate sequence number before accepting RST
361 */
362
363 /*
364 * If the segment contains RST:
365 * Drop the segment - see Stevens, vol. 2, p. 964 and
366 * RFC 1337.
367 */
368 if (thflags & TH_RST)
369 goto drop;
370
371#if 0
372/* PAWS not needed at the moment */
373 /*
374 * RFC 1323 PAWS: If we have a timestamp reply on this segment
375 * and it's less than ts_recent, drop it.
376 */
377 if ((to.to_flags & TOF_TS) != 0 && tp->ts_recent &&
378 TSTMP_LT(to.to_tsval, tp->ts_recent)) {
379 if ((thflags & TH_ACK) == 0)
380 goto drop;
381 goto ack;
382 }
383 /*
384 * ts_recent is never updated because we never accept new segments.
385 */
386#endif
387
388 /*
389 * If a new connection request is received
390 * while in TIME_WAIT, drop the old connection
391 * and start over if the sequence numbers
392 * are above the previous ones.
393 */
394 if ((thflags & TH_SYN) && SEQ_GT(th->th_seq, tw->rcv_nxt)) {
395 tcp_twclose(tw, 0);
396 return (1);
397 }
398
399 /*
400 * Drop the the segment if it does not contain an ACK.
401 */
402 if ((thflags & TH_ACK) == 0)
403 goto drop;
404
405 /*
406 * Reset the 2MSL timer if this is a duplicate FIN.
407 */
408 if (thflags & TH_FIN) {
409 seq = th->th_seq + tlen + (thflags & TH_SYN ? 1 : 0);
410 if (seq + 1 == tw->rcv_nxt)
411 tcp_tw_2msl_reset(tw, 1);
412 }
413
414 /*
415 * Acknowledge the segment if it has data or is not a duplicate ACK.
416 */
417 if (thflags != TH_ACK || tlen != 0 ||
418 th->th_seq != tw->rcv_nxt || th->th_ack != tw->snd_nxt)
419 tcp_twrespond(tw, TH_ACK);
420drop:
421 INP_WUNLOCK(inp);
422 m_freem(m);
423 return (0);
424}
425
426void
427tcp_twclose(struct tcptw *tw, int reuse)
428{
429 struct socket *so;
430 struct inpcb *inp;
431
432 /*
433 * At this point, we are in one of two situations:
434 *
435 * (1) We have no socket, just an inpcb<->twtcp pair. We can free
436 * all state.
437 *
438 * (2) We have a socket -- if we own a reference, release it and
439 * notify the socket layer.
440 */
441 inp = tw->tw_inpcb;
442 KASSERT((inp->inp_flags & INP_TIMEWAIT), ("tcp_twclose: !timewait"));
443 KASSERT(intotw(inp) == tw, ("tcp_twclose: inp_ppcb != tw"));
444 INP_INFO_WLOCK_ASSERT(&V_tcbinfo); /* tcp_tw_2msl_stop(). */
445 INP_WLOCK_ASSERT(inp);
446
447 tw->tw_inpcb = NULL;
448 tcp_tw_2msl_stop(tw);
449 inp->inp_ppcb = NULL;
450 in_pcbdrop(inp);
451
452 so = inp->inp_socket;
453 if (so != NULL) {
454 /*
455 * If there's a socket, handle two cases: first, we own a
456 * strong reference, which we will now release, or we don't
457 * in which case another reference exists (XXXRW: think
458 * about this more), and we don't need to take action.
459 */
460 if (inp->inp_flags & INP_SOCKREF) {
461 inp->inp_flags &= ~INP_SOCKREF;
462 INP_WUNLOCK(inp);
463 ACCEPT_LOCK();
464 SOCK_LOCK(so);
465 KASSERT(so->so_state & SS_PROTOREF,
466 ("tcp_twclose: INP_SOCKREF && !SS_PROTOREF"));
467 so->so_state &= ~SS_PROTOREF;
468 sofree(so);
469 } else {
470 /*
471 * If we don't own the only reference, the socket and
472 * inpcb need to be left around to be handled by
473 * tcp_usr_detach() later.
474 */
475 INP_WUNLOCK(inp);
476 }
477 } else
478 in_pcbfree(inp);
479 TCPSTAT_INC(tcps_closed);
480 crfree(tw->tw_cred);
481 tw->tw_cred = NULL;
482 if (reuse)
483 return;
484 uma_zfree(V_tcptw_zone, tw);
485}
486
487int
488tcp_twrespond(struct tcptw *tw, int flags)
489{
490 struct inpcb *inp = tw->tw_inpcb;
491 struct tcphdr *th;
492 struct mbuf *m;
493 struct ip *ip = NULL;
494 u_int hdrlen, optlen;
495 int error;
496 struct tcpopt to;
497#ifdef INET6
498 struct ip6_hdr *ip6 = NULL;
499 int isipv6 = inp->inp_inc.inc_flags & INC_ISIPV6;
500#endif
501
502 INP_WLOCK_ASSERT(inp);
503
504 m = m_gethdr(M_DONTWAIT, MT_DATA);
505 if (m == NULL)
506 return (ENOBUFS);
507 m->m_data += max_linkhdr;
508
509#ifdef MAC
510 mac_inpcb_create_mbuf(inp, m);
511#endif
512
513#ifdef INET6
514 if (isipv6) {
515 hdrlen = sizeof(struct ip6_hdr) + sizeof(struct tcphdr);
516 ip6 = mtod(m, struct ip6_hdr *);
517 th = (struct tcphdr *)(ip6 + 1);
518 tcpip_fillheaders(inp, ip6, th);
519 } else
520#endif
521 {
522 hdrlen = sizeof(struct tcpiphdr);
523 ip = mtod(m, struct ip *);
524 th = (struct tcphdr *)(ip + 1);
525 tcpip_fillheaders(inp, ip, th);
526 }
527 to.to_flags = 0;
528
529 /*
530 * Send a timestamp and echo-reply if both our side and our peer
531 * have sent timestamps in our SYN's and this is not a RST.
532 */
533 if (tw->t_recent && flags == TH_ACK) {
534 to.to_flags |= TOF_TS;
535 to.to_tsval = ticks + tw->ts_offset;
536 to.to_tsecr = tw->t_recent;
537 }
538 optlen = tcp_addoptions(&to, (u_char *)(th + 1));
539
540 m->m_len = hdrlen + optlen;
541 m->m_pkthdr.len = m->m_len;
542
543 KASSERT(max_linkhdr + m->m_len <= MHLEN, ("tcptw: mbuf too small"));
544
545 th->th_seq = htonl(tw->snd_nxt);
546 th->th_ack = htonl(tw->rcv_nxt);
547 th->th_off = (sizeof(struct tcphdr) + optlen) >> 2;
548 th->th_flags = flags;
549 th->th_win = htons(tw->last_win);
550
551#ifdef INET6
552 if (isipv6) {
553 th->th_sum = in6_cksum(m, IPPROTO_TCP, sizeof(struct ip6_hdr),
554 sizeof(struct tcphdr) + optlen);
555 ip6->ip6_hlim = in6_selecthlim(inp, NULL);
556 error = ip6_output(m, inp->in6p_outputopts, NULL,
557 (tw->tw_so_options & SO_DONTROUTE), NULL, NULL, inp);
558 } else
559#endif
560 {
561 th->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr,
562 htons(sizeof(struct tcphdr) + optlen + IPPROTO_TCP));
563 m->m_pkthdr.csum_flags = CSUM_TCP;
564 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum);
565 ip->ip_len = m->m_pkthdr.len;
566 if (V_path_mtu_discovery)
567 ip->ip_off |= IP_DF;
568 error = ip_output(m, inp->inp_options, NULL,
569 ((tw->tw_so_options & SO_DONTROUTE) ? IP_ROUTETOIF : 0),
570 NULL, inp);
571 }
572 if (flags & TH_ACK)
573 TCPSTAT_INC(tcps_sndacks);
574 else
575 TCPSTAT_INC(tcps_sndctrl);
576 TCPSTAT_INC(tcps_sndtotal);
577 return (error);
578}
579
580static void
581tcp_tw_2msl_reset(struct tcptw *tw, int rearm)
582{
583
584 INP_INFO_WLOCK_ASSERT(&V_tcbinfo);
585 INP_WLOCK_ASSERT(tw->tw_inpcb);
586 if (rearm)
587 TAILQ_REMOVE(&V_twq_2msl, tw, tw_2msl);
588 tw->tw_time = ticks + 2 * tcp_msl;
589 TAILQ_INSERT_TAIL(&V_twq_2msl, tw, tw_2msl);
590}
591
592static void
593tcp_tw_2msl_stop(struct tcptw *tw)
594{
595
596 INP_INFO_WLOCK_ASSERT(&V_tcbinfo);
597 TAILQ_REMOVE(&V_twq_2msl, tw, tw_2msl);
598}
599
600struct tcptw *
601tcp_tw_2msl_scan(int reuse)
602{
603 struct tcptw *tw;
604
605 INP_INFO_WLOCK_ASSERT(&V_tcbinfo);
606 for (;;) {
607 tw = TAILQ_FIRST(&V_twq_2msl);
608 if (tw == NULL || (!reuse && (tw->tw_time - ticks) > 0))
609 break;
610 INP_WLOCK(tw->tw_inpcb);
611 tcp_twclose(tw, reuse);
612 if (reuse)
613 return (tw);
614 }
615 return (NULL);
616}
| 152SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, nolocaltimewait, CTLFLAG_RW,
153 &VNET_NAME(nolocaltimewait), 0,
154 "Do not create compressed TCP TIME_WAIT entries for local connections");
155
156void
157tcp_tw_zone_change(void)
158{
159
160 if (maxtcptw == 0)
161 uma_zone_set_max(V_tcptw_zone, tcptw_auto_size());
162}
163
164void
165tcp_tw_init(void)
166{
167
168 V_tcptw_zone = uma_zcreate("tcptw", sizeof(struct tcptw),
169 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
170 TUNABLE_INT_FETCH("net.inet.tcp.maxtcptw", &maxtcptw);
171 if (maxtcptw == 0)
172 uma_zone_set_max(V_tcptw_zone, tcptw_auto_size());
173 else
174 uma_zone_set_max(V_tcptw_zone, maxtcptw);
175 TAILQ_INIT(&V_twq_2msl);
176}
177
178#ifdef VIMAGE
179void
180tcp_tw_destroy(void)
181{
182 struct tcptw *tw;
183
184 INP_INFO_WLOCK(&V_tcbinfo);
185 while((tw = TAILQ_FIRST(&V_twq_2msl)) != NULL)
186 tcp_twclose(tw, 0);
187 INP_INFO_WUNLOCK(&V_tcbinfo);
188
189 uma_zdestroy(V_tcptw_zone);
190}
191#endif
192
193/*
194 * Move a TCP connection into TIME_WAIT state.
195 * tcbinfo is locked.
196 * inp is locked, and is unlocked before returning.
197 */
198void
199tcp_twstart(struct tcpcb *tp)
200{
201 struct tcptw *tw;
202 struct inpcb *inp = tp->t_inpcb;
203 int acknow;
204 struct socket *so;
205
206 INP_INFO_WLOCK_ASSERT(&V_tcbinfo); /* tcp_tw_2msl_reset(). */
207 INP_WLOCK_ASSERT(inp);
208
209 if (V_nolocaltimewait && in_localip(inp->inp_faddr)) {
210 tp = tcp_close(tp);
211 if (tp != NULL)
212 INP_WUNLOCK(inp);
213 return;
214 }
215
216 tw = uma_zalloc(V_tcptw_zone, M_NOWAIT);
217 if (tw == NULL) {
218 tw = tcp_tw_2msl_scan(1);
219 if (tw == NULL) {
220 tp = tcp_close(tp);
221 if (tp != NULL)
222 INP_WUNLOCK(inp);
223 return;
224 }
225 }
226 tw->tw_inpcb = inp;
227
228 /*
229 * Recover last window size sent.
230 */
231 tw->last_win = (tp->rcv_adv - tp->rcv_nxt) >> tp->rcv_scale;
232
233 /*
234 * Set t_recent if timestamps are used on the connection.
235 */
236 if ((tp->t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP|TF_NOOPT)) ==
237 (TF_REQ_TSTMP|TF_RCVD_TSTMP)) {
238 tw->t_recent = tp->ts_recent;
239 tw->ts_offset = tp->ts_offset;
240 } else {
241 tw->t_recent = 0;
242 tw->ts_offset = 0;
243 }
244
245 tw->snd_nxt = tp->snd_nxt;
246 tw->rcv_nxt = tp->rcv_nxt;
247 tw->iss = tp->iss;
248 tw->irs = tp->irs;
249 tw->t_starttime = tp->t_starttime;
250 tw->tw_time = 0;
251
252/* XXX
253 * If this code will
254 * be used for fin-wait-2 state also, then we may need
255 * a ts_recent from the last segment.
256 */
257 acknow = tp->t_flags & TF_ACKNOW;
258
259 /*
260 * First, discard tcpcb state, which includes stopping its timers and
261 * freeing it. tcp_discardcb() used to also release the inpcb, but
262 * that work is now done in the caller.
263 *
264 * Note: soisdisconnected() call used to be made in tcp_discardcb(),
265 * and might not be needed here any longer.
266 */
267 tcp_discardcb(tp);
268 so = inp->inp_socket;
269 soisdisconnected(so);
270 tw->tw_cred = crhold(so->so_cred);
271 SOCK_LOCK(so);
272 tw->tw_so_options = so->so_options;
273 SOCK_UNLOCK(so);
274 if (acknow)
275 tcp_twrespond(tw, TH_ACK);
276 inp->inp_ppcb = tw;
277 inp->inp_flags |= INP_TIMEWAIT;
278 tcp_tw_2msl_reset(tw, 0);
279
280 /*
281 * If the inpcb owns the sole reference to the socket, then we can
282 * detach and free the socket as it is not needed in time wait.
283 */
284 if (inp->inp_flags & INP_SOCKREF) {
285 KASSERT(so->so_state & SS_PROTOREF,
286 ("tcp_twstart: !SS_PROTOREF"));
287 inp->inp_flags &= ~INP_SOCKREF;
288 INP_WUNLOCK(inp);
289 ACCEPT_LOCK();
290 SOCK_LOCK(so);
291 so->so_state &= ~SS_PROTOREF;
292 sofree(so);
293 } else
294 INP_WUNLOCK(inp);
295}
296
297#if 0
298/*
299 * The appromixate rate of ISN increase of Microsoft TCP stacks;
300 * the actual rate is slightly higher due to the addition of
301 * random positive increments.
302 *
303 * Most other new OSes use semi-randomized ISN values, so we
304 * do not need to worry about them.
305 */
306#define MS_ISN_BYTES_PER_SECOND 250000
307
308/*
309 * Determine if the ISN we will generate has advanced beyond the last
310 * sequence number used by the previous connection. If so, indicate
311 * that it is safe to recycle this tw socket by returning 1.
312 */
313int
314tcp_twrecycleable(struct tcptw *tw)
315{
316 tcp_seq new_iss = tw->iss;
317 tcp_seq new_irs = tw->irs;
318
319 INP_INFO_WLOCK_ASSERT(&V_tcbinfo);
320 new_iss += (ticks - tw->t_starttime) * (ISN_BYTES_PER_SECOND / hz);
321 new_irs += (ticks - tw->t_starttime) * (MS_ISN_BYTES_PER_SECOND / hz);
322
323 if (SEQ_GT(new_iss, tw->snd_nxt) && SEQ_GT(new_irs, tw->rcv_nxt))
324 return (1);
325 else
326 return (0);
327}
328#endif
329
330/*
331 * Returns 1 if the TIME_WAIT state was killed and we should start over,
332 * looking for a pcb in the listen state. Returns 0 otherwise.
333 */
334int
335tcp_twcheck(struct inpcb *inp, struct tcpopt *to, struct tcphdr *th,
336 struct mbuf *m, int tlen)
337{
338 struct tcptw *tw;
339 int thflags;
340 tcp_seq seq;
341
342 /* tcbinfo lock required for tcp_twclose(), tcp_tw_2msl_reset(). */
343 INP_INFO_WLOCK_ASSERT(&V_tcbinfo);
344 INP_WLOCK_ASSERT(inp);
345
346 /*
347 * XXXRW: Time wait state for inpcb has been recycled, but inpcb is
348 * still present. This is undesirable, but temporarily necessary
349 * until we work out how to handle inpcb's who's timewait state has
350 * been removed.
351 */
352 tw = intotw(inp);
353 if (tw == NULL)
354 goto drop;
355
356 thflags = th->th_flags;
357
358 /*
359 * NOTE: for FIN_WAIT_2 (to be added later),
360 * must validate sequence number before accepting RST
361 */
362
363 /*
364 * If the segment contains RST:
365 * Drop the segment - see Stevens, vol. 2, p. 964 and
366 * RFC 1337.
367 */
368 if (thflags & TH_RST)
369 goto drop;
370
371#if 0
372/* PAWS not needed at the moment */
373 /*
374 * RFC 1323 PAWS: If we have a timestamp reply on this segment
375 * and it's less than ts_recent, drop it.
376 */
377 if ((to.to_flags & TOF_TS) != 0 && tp->ts_recent &&
378 TSTMP_LT(to.to_tsval, tp->ts_recent)) {
379 if ((thflags & TH_ACK) == 0)
380 goto drop;
381 goto ack;
382 }
383 /*
384 * ts_recent is never updated because we never accept new segments.
385 */
386#endif
387
388 /*
389 * If a new connection request is received
390 * while in TIME_WAIT, drop the old connection
391 * and start over if the sequence numbers
392 * are above the previous ones.
393 */
394 if ((thflags & TH_SYN) && SEQ_GT(th->th_seq, tw->rcv_nxt)) {
395 tcp_twclose(tw, 0);
396 return (1);
397 }
398
399 /*
400 * Drop the the segment if it does not contain an ACK.
401 */
402 if ((thflags & TH_ACK) == 0)
403 goto drop;
404
405 /*
406 * Reset the 2MSL timer if this is a duplicate FIN.
407 */
408 if (thflags & TH_FIN) {
409 seq = th->th_seq + tlen + (thflags & TH_SYN ? 1 : 0);
410 if (seq + 1 == tw->rcv_nxt)
411 tcp_tw_2msl_reset(tw, 1);
412 }
413
414 /*
415 * Acknowledge the segment if it has data or is not a duplicate ACK.
416 */
417 if (thflags != TH_ACK || tlen != 0 ||
418 th->th_seq != tw->rcv_nxt || th->th_ack != tw->snd_nxt)
419 tcp_twrespond(tw, TH_ACK);
420drop:
421 INP_WUNLOCK(inp);
422 m_freem(m);
423 return (0);
424}
425
426void
427tcp_twclose(struct tcptw *tw, int reuse)
428{
429 struct socket *so;
430 struct inpcb *inp;
431
432 /*
433 * At this point, we are in one of two situations:
434 *
435 * (1) We have no socket, just an inpcb<->twtcp pair. We can free
436 * all state.
437 *
438 * (2) We have a socket -- if we own a reference, release it and
439 * notify the socket layer.
440 */
441 inp = tw->tw_inpcb;
442 KASSERT((inp->inp_flags & INP_TIMEWAIT), ("tcp_twclose: !timewait"));
443 KASSERT(intotw(inp) == tw, ("tcp_twclose: inp_ppcb != tw"));
444 INP_INFO_WLOCK_ASSERT(&V_tcbinfo); /* tcp_tw_2msl_stop(). */
445 INP_WLOCK_ASSERT(inp);
446
447 tw->tw_inpcb = NULL;
448 tcp_tw_2msl_stop(tw);
449 inp->inp_ppcb = NULL;
450 in_pcbdrop(inp);
451
452 so = inp->inp_socket;
453 if (so != NULL) {
454 /*
455 * If there's a socket, handle two cases: first, we own a
456 * strong reference, which we will now release, or we don't
457 * in which case another reference exists (XXXRW: think
458 * about this more), and we don't need to take action.
459 */
460 if (inp->inp_flags & INP_SOCKREF) {
461 inp->inp_flags &= ~INP_SOCKREF;
462 INP_WUNLOCK(inp);
463 ACCEPT_LOCK();
464 SOCK_LOCK(so);
465 KASSERT(so->so_state & SS_PROTOREF,
466 ("tcp_twclose: INP_SOCKREF && !SS_PROTOREF"));
467 so->so_state &= ~SS_PROTOREF;
468 sofree(so);
469 } else {
470 /*
471 * If we don't own the only reference, the socket and
472 * inpcb need to be left around to be handled by
473 * tcp_usr_detach() later.
474 */
475 INP_WUNLOCK(inp);
476 }
477 } else
478 in_pcbfree(inp);
479 TCPSTAT_INC(tcps_closed);
480 crfree(tw->tw_cred);
481 tw->tw_cred = NULL;
482 if (reuse)
483 return;
484 uma_zfree(V_tcptw_zone, tw);
485}
486
487int
488tcp_twrespond(struct tcptw *tw, int flags)
489{
490 struct inpcb *inp = tw->tw_inpcb;
491 struct tcphdr *th;
492 struct mbuf *m;
493 struct ip *ip = NULL;
494 u_int hdrlen, optlen;
495 int error;
496 struct tcpopt to;
497#ifdef INET6
498 struct ip6_hdr *ip6 = NULL;
499 int isipv6 = inp->inp_inc.inc_flags & INC_ISIPV6;
500#endif
501
502 INP_WLOCK_ASSERT(inp);
503
504 m = m_gethdr(M_DONTWAIT, MT_DATA);
505 if (m == NULL)
506 return (ENOBUFS);
507 m->m_data += max_linkhdr;
508
509#ifdef MAC
510 mac_inpcb_create_mbuf(inp, m);
511#endif
512
513#ifdef INET6
514 if (isipv6) {
515 hdrlen = sizeof(struct ip6_hdr) + sizeof(struct tcphdr);
516 ip6 = mtod(m, struct ip6_hdr *);
517 th = (struct tcphdr *)(ip6 + 1);
518 tcpip_fillheaders(inp, ip6, th);
519 } else
520#endif
521 {
522 hdrlen = sizeof(struct tcpiphdr);
523 ip = mtod(m, struct ip *);
524 th = (struct tcphdr *)(ip + 1);
525 tcpip_fillheaders(inp, ip, th);
526 }
527 to.to_flags = 0;
528
529 /*
530 * Send a timestamp and echo-reply if both our side and our peer
531 * have sent timestamps in our SYN's and this is not a RST.
532 */
533 if (tw->t_recent && flags == TH_ACK) {
534 to.to_flags |= TOF_TS;
535 to.to_tsval = ticks + tw->ts_offset;
536 to.to_tsecr = tw->t_recent;
537 }
538 optlen = tcp_addoptions(&to, (u_char *)(th + 1));
539
540 m->m_len = hdrlen + optlen;
541 m->m_pkthdr.len = m->m_len;
542
543 KASSERT(max_linkhdr + m->m_len <= MHLEN, ("tcptw: mbuf too small"));
544
545 th->th_seq = htonl(tw->snd_nxt);
546 th->th_ack = htonl(tw->rcv_nxt);
547 th->th_off = (sizeof(struct tcphdr) + optlen) >> 2;
548 th->th_flags = flags;
549 th->th_win = htons(tw->last_win);
550
551#ifdef INET6
552 if (isipv6) {
553 th->th_sum = in6_cksum(m, IPPROTO_TCP, sizeof(struct ip6_hdr),
554 sizeof(struct tcphdr) + optlen);
555 ip6->ip6_hlim = in6_selecthlim(inp, NULL);
556 error = ip6_output(m, inp->in6p_outputopts, NULL,
557 (tw->tw_so_options & SO_DONTROUTE), NULL, NULL, inp);
558 } else
559#endif
560 {
561 th->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr,
562 htons(sizeof(struct tcphdr) + optlen + IPPROTO_TCP));
563 m->m_pkthdr.csum_flags = CSUM_TCP;
564 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum);
565 ip->ip_len = m->m_pkthdr.len;
566 if (V_path_mtu_discovery)
567 ip->ip_off |= IP_DF;
568 error = ip_output(m, inp->inp_options, NULL,
569 ((tw->tw_so_options & SO_DONTROUTE) ? IP_ROUTETOIF : 0),
570 NULL, inp);
571 }
572 if (flags & TH_ACK)
573 TCPSTAT_INC(tcps_sndacks);
574 else
575 TCPSTAT_INC(tcps_sndctrl);
576 TCPSTAT_INC(tcps_sndtotal);
577 return (error);
578}
579
580static void
581tcp_tw_2msl_reset(struct tcptw *tw, int rearm)
582{
583
584 INP_INFO_WLOCK_ASSERT(&V_tcbinfo);
585 INP_WLOCK_ASSERT(tw->tw_inpcb);
586 if (rearm)
587 TAILQ_REMOVE(&V_twq_2msl, tw, tw_2msl);
588 tw->tw_time = ticks + 2 * tcp_msl;
589 TAILQ_INSERT_TAIL(&V_twq_2msl, tw, tw_2msl);
590}
591
592static void
593tcp_tw_2msl_stop(struct tcptw *tw)
594{
595
596 INP_INFO_WLOCK_ASSERT(&V_tcbinfo);
597 TAILQ_REMOVE(&V_twq_2msl, tw, tw_2msl);
598}
599
600struct tcptw *
601tcp_tw_2msl_scan(int reuse)
602{
603 struct tcptw *tw;
604
605 INP_INFO_WLOCK_ASSERT(&V_tcbinfo);
606 for (;;) {
607 tw = TAILQ_FIRST(&V_twq_2msl);
608 if (tw == NULL || (!reuse && (tw->tw_time - ticks) > 0))
609 break;
610 INP_WLOCK(tw->tw_inpcb);
611 tcp_twclose(tw, reuse);
612 if (reuse)
613 return (tw);
614 }
615 return (NULL);
616}
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