35 */
36
37#include "opt_compat.h"
38#include "opt_inet6.h"
39#include "opt_ipsec.h"
40#include "opt_mac.h"
41#include "opt_tcpdebug.h"
42
43#include <sys/param.h>
44#include <sys/systm.h>
45#include <sys/callout.h>
46#include <sys/kernel.h>
47#include <sys/sysctl.h>
48#include <sys/mac.h>
49#include <sys/malloc.h>
50#include <sys/mbuf.h>
51#ifdef INET6
52#include <sys/domain.h>
53#endif
54#include <sys/proc.h>
55#include <sys/socket.h>
56#include <sys/socketvar.h>
57#include <sys/protosw.h>
58#include <sys/random.h>
59
60#include <vm/uma.h>
61
62#include <net/route.h>
63#include <net/if.h>
64
65#include <netinet/in.h>
66#include <netinet/in_systm.h>
67#include <netinet/ip.h>
68#ifdef INET6
69#include <netinet/ip6.h>
70#endif
71#include <netinet/in_pcb.h>
72#ifdef INET6
73#include <netinet6/in6_pcb.h>
74#endif
75#include <netinet/in_var.h>
76#include <netinet/ip_var.h>
77#ifdef INET6
78#include <netinet6/ip6_var.h>
79#endif
80#include <netinet/tcp.h>
81#include <netinet/tcp_fsm.h>
82#include <netinet/tcp_seq.h>
83#include <netinet/tcp_timer.h>
84#include <netinet/tcp_var.h>
85#ifdef INET6
86#include <netinet6/tcp6_var.h>
87#endif
88#include <netinet/tcpip.h>
89#ifdef TCPDEBUG
90#include <netinet/tcp_debug.h>
91#endif
92#include <netinet6/ip6protosw.h>
93
94#ifdef IPSEC
95#include <netinet6/ipsec.h>
96#ifdef INET6
97#include <netinet6/ipsec6.h>
98#endif
99#endif /*IPSEC*/
100
101#ifdef FAST_IPSEC
102#include <netipsec/ipsec.h>
103#ifdef INET6
104#include <netipsec/ipsec6.h>
105#endif
106#define IPSEC
107#endif /*FAST_IPSEC*/
108
109#include <machine/in_cksum.h>
110#include <sys/md5.h>
111
112int tcp_mssdflt = TCP_MSS;
113SYSCTL_INT(_net_inet_tcp, TCPCTL_MSSDFLT, mssdflt, CTLFLAG_RW,
114 &tcp_mssdflt , 0, "Default TCP Maximum Segment Size");
115
116#ifdef INET6
117int tcp_v6mssdflt = TCP6_MSS;
118SYSCTL_INT(_net_inet_tcp, TCPCTL_V6MSSDFLT, v6mssdflt,
119 CTLFLAG_RW, &tcp_v6mssdflt , 0,
120 "Default TCP Maximum Segment Size for IPv6");
121#endif
122
123#if 0
124static int tcp_rttdflt = TCPTV_SRTTDFLT / PR_SLOWHZ;
125SYSCTL_INT(_net_inet_tcp, TCPCTL_RTTDFLT, rttdflt, CTLFLAG_RW,
126 &tcp_rttdflt , 0, "Default maximum TCP Round Trip Time");
127#endif
128
129int tcp_do_rfc1323 = 1;
130SYSCTL_INT(_net_inet_tcp, TCPCTL_DO_RFC1323, rfc1323, CTLFLAG_RW,
131 &tcp_do_rfc1323 , 0, "Enable rfc1323 (high performance TCP) extensions");
132
133int tcp_do_rfc1644 = 0;
134SYSCTL_INT(_net_inet_tcp, TCPCTL_DO_RFC1644, rfc1644, CTLFLAG_RW,
135 &tcp_do_rfc1644 , 0, "Enable rfc1644 (TTCP) extensions");
136
137static int tcp_tcbhashsize = 0;
138SYSCTL_INT(_net_inet_tcp, OID_AUTO, tcbhashsize, CTLFLAG_RD,
139 &tcp_tcbhashsize, 0, "Size of TCP control-block hashtable");
140
141static int do_tcpdrain = 1;
142SYSCTL_INT(_net_inet_tcp, OID_AUTO, do_tcpdrain, CTLFLAG_RW, &do_tcpdrain, 0,
143 "Enable tcp_drain routine for extra help when low on mbufs");
144
145SYSCTL_INT(_net_inet_tcp, OID_AUTO, pcbcount, CTLFLAG_RD,
146 &tcbinfo.ipi_count, 0, "Number of active PCBs");
147
148static int icmp_may_rst = 1;
149SYSCTL_INT(_net_inet_tcp, OID_AUTO, icmp_may_rst, CTLFLAG_RW, &icmp_may_rst, 0,
150 "Certain ICMP unreachable messages may abort connections in SYN_SENT");
151
152static int tcp_isn_reseed_interval = 0;
153SYSCTL_INT(_net_inet_tcp, OID_AUTO, isn_reseed_interval, CTLFLAG_RW,
154 &tcp_isn_reseed_interval, 0, "Seconds between reseeding of ISN secret");
155
156/*
157 * TCP bandwidth limiting sysctls. Note that the default lower bound of
158 * 1024 exists only for debugging. A good production default would be
159 * something like 6100.
160 */
161static int tcp_inflight_enable = 0;
162SYSCTL_INT(_net_inet_tcp, OID_AUTO, inflight_enable, CTLFLAG_RW,
163 &tcp_inflight_enable, 0, "Enable automatic TCP inflight data limiting");
164
165static int tcp_inflight_debug = 0;
166SYSCTL_INT(_net_inet_tcp, OID_AUTO, inflight_debug, CTLFLAG_RW,
167 &tcp_inflight_debug, 0, "Debug TCP inflight calculations");
168
169static int tcp_inflight_min = 6144;
170SYSCTL_INT(_net_inet_tcp, OID_AUTO, inflight_min, CTLFLAG_RW,
171 &tcp_inflight_min, 0, "Lower-bound for TCP inflight window");
172
173static int tcp_inflight_max = TCP_MAXWIN << TCP_MAX_WINSHIFT;
174SYSCTL_INT(_net_inet_tcp, OID_AUTO, inflight_max, CTLFLAG_RW,
175 &tcp_inflight_max, 0, "Upper-bound for TCP inflight window");
176static int tcp_inflight_stab = 20;
177SYSCTL_INT(_net_inet_tcp, OID_AUTO, inflight_stab, CTLFLAG_RW,
178 &tcp_inflight_stab, 0, "Inflight Algorithm Stabilization 20 = 2 packets");
179
180static void tcp_cleartaocache(void);
181static struct inpcb *tcp_notify(struct inpcb *, int);
182static void tcp_discardcb(struct tcpcb *);
183
184/*
185 * Target size of TCP PCB hash tables. Must be a power of two.
186 *
187 * Note that this can be overridden by the kernel environment
188 * variable net.inet.tcp.tcbhashsize
189 */
190#ifndef TCBHASHSIZE
191#define TCBHASHSIZE 512
192#endif
193
194/*
195 * XXX
196 * Callouts should be moved into struct tcp directly. They are currently
197 * separate becuase the tcpcb structure is exported to userland for sysctl
198 * parsing purposes, which do not know about callouts.
199 */
200struct tcpcb_mem {
201 struct tcpcb tcb;
202 struct callout tcpcb_mem_rexmt, tcpcb_mem_persist, tcpcb_mem_keep;
203 struct callout tcpcb_mem_2msl, tcpcb_mem_delack;
204};
205
206static uma_zone_t tcpcb_zone;
207static uma_zone_t tcptw_zone;
208
209/*
210 * Tcp initialization
211 */
212void
213tcp_init()
214{
215 int hashsize = TCBHASHSIZE;
216
217 tcp_ccgen = 1;
218 tcp_cleartaocache();
219
220 tcp_delacktime = TCPTV_DELACK;
221 tcp_keepinit = TCPTV_KEEP_INIT;
222 tcp_keepidle = TCPTV_KEEP_IDLE;
223 tcp_keepintvl = TCPTV_KEEPINTVL;
224 tcp_maxpersistidle = TCPTV_KEEP_IDLE;
225 tcp_msl = TCPTV_MSL;
226 tcp_rexmit_min = TCPTV_MIN;
227 tcp_rexmit_slop = TCPTV_CPU_VAR;
228
229 INP_INFO_LOCK_INIT(&tcbinfo, "tcp");
230 LIST_INIT(&tcb);
231 tcbinfo.listhead = &tcb;
232 TUNABLE_INT_FETCH("net.inet.tcp.tcbhashsize", &hashsize);
233 if (!powerof2(hashsize)) {
234 printf("WARNING: TCB hash size not a power of 2\n");
235 hashsize = 512; /* safe default */
236 }
237 tcp_tcbhashsize = hashsize;
238 tcbinfo.hashbase = hashinit(hashsize, M_PCB, &tcbinfo.hashmask);
239 tcbinfo.porthashbase = hashinit(hashsize, M_PCB,
240 &tcbinfo.porthashmask);
241 tcbinfo.ipi_zone = uma_zcreate("inpcb", sizeof(struct inpcb),
242 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
243 uma_zone_set_max(tcbinfo.ipi_zone, maxsockets);
244#ifdef INET6
245#define TCP_MINPROTOHDR (sizeof(struct ip6_hdr) + sizeof(struct tcphdr))
246#else /* INET6 */
247#define TCP_MINPROTOHDR (sizeof(struct tcpiphdr))
248#endif /* INET6 */
249 if (max_protohdr < TCP_MINPROTOHDR)
250 max_protohdr = TCP_MINPROTOHDR;
251 if (max_linkhdr + TCP_MINPROTOHDR > MHLEN)
252 panic("tcp_init");
253#undef TCP_MINPROTOHDR
254 /*
255 * These have to be type stable for the benefit of the timers.
256 */
257 tcpcb_zone = uma_zcreate("tcpcb", sizeof(struct tcpcb_mem),
258 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
259 uma_zone_set_max(tcpcb_zone, maxsockets);
260 tcptw_zone = uma_zcreate("tcptw", sizeof(struct tcptw),
261 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
262 uma_zone_set_max(tcptw_zone, maxsockets);
263 tcp_timer_init();
264 syncache_init();
265}
266
267/*
268 * Fill in the IP and TCP headers for an outgoing packet, given the tcpcb.
269 * tcp_template used to store this data in mbufs, but we now recopy it out
270 * of the tcpcb each time to conserve mbufs.
271 */
272void
273tcpip_fillheaders(inp, ip_ptr, tcp_ptr)
274 struct inpcb *inp;
275 void *ip_ptr;
276 void *tcp_ptr;
277{
278 struct tcphdr *th = (struct tcphdr *)tcp_ptr;
279
280#ifdef INET6
281 if ((inp->inp_vflag & INP_IPV6) != 0) {
282 struct ip6_hdr *ip6;
283
284 ip6 = (struct ip6_hdr *)ip_ptr;
285 ip6->ip6_flow = (ip6->ip6_flow & ~IPV6_FLOWINFO_MASK) |
286 (inp->in6p_flowinfo & IPV6_FLOWINFO_MASK);
287 ip6->ip6_vfc = (ip6->ip6_vfc & ~IPV6_VERSION_MASK) |
288 (IPV6_VERSION & IPV6_VERSION_MASK);
289 ip6->ip6_nxt = IPPROTO_TCP;
290 ip6->ip6_plen = sizeof(struct tcphdr);
291 ip6->ip6_src = inp->in6p_laddr;
292 ip6->ip6_dst = inp->in6p_faddr;
293 } else
294#endif
295 {
296 struct ip *ip;
297
298 ip = (struct ip *)ip_ptr;
299 ip->ip_v = IPVERSION;
300 ip->ip_hl = 5;
301 ip->ip_tos = inp->inp_ip_tos;
302 ip->ip_len = 0;
303 ip->ip_id = 0;
304 ip->ip_off = 0;
305 ip->ip_ttl = inp->inp_ip_ttl;
306 ip->ip_sum = 0;
307 ip->ip_p = IPPROTO_TCP;
308 ip->ip_src = inp->inp_laddr;
309 ip->ip_dst = inp->inp_faddr;
310 }
311 th->th_sport = inp->inp_lport;
312 th->th_dport = inp->inp_fport;
313 th->th_seq = 0;
314 th->th_ack = 0;
315 th->th_x2 = 0;
316 th->th_off = 5;
317 th->th_flags = 0;
318 th->th_win = 0;
319 th->th_urp = 0;
320 th->th_sum = 0; /* in_pseudo() is called later for ipv4 */
321}
322
323/*
324 * Create template to be used to send tcp packets on a connection.
325 * Allocates an mbuf and fills in a skeletal tcp/ip header. The only
326 * use for this function is in keepalives, which use tcp_respond.
327 */
328struct tcptemp *
329tcpip_maketemplate(inp)
330 struct inpcb *inp;
331{
332 struct mbuf *m;
333 struct tcptemp *n;
334
335 m = m_get(M_DONTWAIT, MT_HEADER);
336 if (m == NULL)
337 return (0);
338 m->m_len = sizeof(struct tcptemp);
339 n = mtod(m, struct tcptemp *);
340
341 tcpip_fillheaders(inp, (void *)&n->tt_ipgen, (void *)&n->tt_t);
342 return (n);
343}
344
345/*
346 * Send a single message to the TCP at address specified by
347 * the given TCP/IP header. If m == 0, then we make a copy
348 * of the tcpiphdr at ti and send directly to the addressed host.
349 * This is used to force keep alive messages out using the TCP
350 * template for a connection. If flags are given then we send
351 * a message back to the TCP which originated the * segment ti,
352 * and discard the mbuf containing it and any other attached mbufs.
353 *
354 * In any case the ack and sequence number of the transmitted
355 * segment are as specified by the parameters.
356 *
357 * NOTE: If m != NULL, then ti must point to *inside* the mbuf.
358 */
359void
360tcp_respond(tp, ipgen, th, m, ack, seq, flags)
361 struct tcpcb *tp;
362 void *ipgen;
363 register struct tcphdr *th;
364 register struct mbuf *m;
365 tcp_seq ack, seq;
366 int flags;
367{
368 register int tlen;
369 int win = 0;
370 struct route *ro = 0;
371 struct route sro;
372 struct ip *ip;
373 struct tcphdr *nth;
374#ifdef INET6
375 struct route_in6 *ro6 = 0;
376 struct route_in6 sro6;
377 struct ip6_hdr *ip6;
378 int isipv6;
379#endif /* INET6 */
380 int ipflags = 0;
381
382 KASSERT(tp != NULL || m != NULL, ("tcp_respond: tp and m both NULL"));
383
384#ifdef INET6
385 isipv6 = ((struct ip *)ipgen)->ip_v == 6;
386 ip6 = ipgen;
387#endif /* INET6 */
388 ip = ipgen;
389
390 if (tp) {
391 if (!(flags & TH_RST)) {
392 win = sbspace(&tp->t_inpcb->inp_socket->so_rcv);
393 if (win > (long)TCP_MAXWIN << tp->rcv_scale)
394 win = (long)TCP_MAXWIN << tp->rcv_scale;
395 }
396#ifdef INET6
397 if (isipv6)
398 ro6 = &tp->t_inpcb->in6p_route;
399 else
400#endif /* INET6 */
401 ro = &tp->t_inpcb->inp_route;
402 } else {
403#ifdef INET6
404 if (isipv6) {
405 ro6 = &sro6;
406 bzero(ro6, sizeof *ro6);
407 } else
408#endif /* INET6 */
409 {
410 ro = &sro;
411 bzero(ro, sizeof *ro);
412 }
413 }
414 if (m == 0) {
415 m = m_gethdr(M_DONTWAIT, MT_HEADER);
416 if (m == NULL)
417 return;
418 tlen = 0;
419 m->m_data += max_linkhdr;
420#ifdef INET6
421 if (isipv6) {
422 bcopy((caddr_t)ip6, mtod(m, caddr_t),
423 sizeof(struct ip6_hdr));
424 ip6 = mtod(m, struct ip6_hdr *);
425 nth = (struct tcphdr *)(ip6 + 1);
426 } else
427#endif /* INET6 */
428 {
429 bcopy((caddr_t)ip, mtod(m, caddr_t), sizeof(struct ip));
430 ip = mtod(m, struct ip *);
431 nth = (struct tcphdr *)(ip + 1);
432 }
433 bcopy((caddr_t)th, (caddr_t)nth, sizeof(struct tcphdr));
434 flags = TH_ACK;
435 } else {
436 m_freem(m->m_next);
437 m->m_next = 0;
438 m->m_data = (caddr_t)ipgen;
439 /* m_len is set later */
440 tlen = 0;
441#define xchg(a,b,type) { type t; t=a; a=b; b=t; }
442#ifdef INET6
443 if (isipv6) {
444 xchg(ip6->ip6_dst, ip6->ip6_src, struct in6_addr);
445 nth = (struct tcphdr *)(ip6 + 1);
446 } else
447#endif /* INET6 */
448 {
449 xchg(ip->ip_dst.s_addr, ip->ip_src.s_addr, n_long);
450 nth = (struct tcphdr *)(ip + 1);
451 }
452 if (th != nth) {
453 /*
454 * this is usually a case when an extension header
455 * exists between the IPv6 header and the
456 * TCP header.
457 */
458 nth->th_sport = th->th_sport;
459 nth->th_dport = th->th_dport;
460 }
461 xchg(nth->th_dport, nth->th_sport, n_short);
462#undef xchg
463 }
464#ifdef INET6
465 if (isipv6) {
466 ip6->ip6_flow = 0;
467 ip6->ip6_vfc = IPV6_VERSION;
468 ip6->ip6_nxt = IPPROTO_TCP;
469 ip6->ip6_plen = htons((u_short)(sizeof (struct tcphdr) +
470 tlen));
471 tlen += sizeof (struct ip6_hdr) + sizeof (struct tcphdr);
472 } else
473#endif
474 {
475 tlen += sizeof (struct tcpiphdr);
476 ip->ip_len = tlen;
477 ip->ip_ttl = ip_defttl;
478 }
479 m->m_len = tlen;
480 m->m_pkthdr.len = tlen;
481 m->m_pkthdr.rcvif = (struct ifnet *) 0;
482#ifdef MAC
483 if (tp != NULL && tp->t_inpcb != NULL) {
484 /*
485 * Packet is associated with a socket, so allow the
486 * label of the response to reflect the socket label.
487 */
488 mac_create_mbuf_from_socket(tp->t_inpcb->inp_socket, m);
489 } else {
490 /*
491 * Packet is not associated with a socket, so possibly
492 * update the label in place.
493 */
494 mac_reflect_mbuf_tcp(m);
495 }
496#endif
497 nth->th_seq = htonl(seq);
498 nth->th_ack = htonl(ack);
499 nth->th_x2 = 0;
500 nth->th_off = sizeof (struct tcphdr) >> 2;
501 nth->th_flags = flags;
502 if (tp)
503 nth->th_win = htons((u_short) (win >> tp->rcv_scale));
504 else
505 nth->th_win = htons((u_short)win);
506 nth->th_urp = 0;
507#ifdef INET6
508 if (isipv6) {
509 nth->th_sum = 0;
510 nth->th_sum = in6_cksum(m, IPPROTO_TCP,
511 sizeof(struct ip6_hdr),
512 tlen - sizeof(struct ip6_hdr));
513 ip6->ip6_hlim = in6_selecthlim(tp ? tp->t_inpcb : NULL,
514 ro6 && ro6->ro_rt ?
515 ro6->ro_rt->rt_ifp :
516 NULL);
517 } else
518#endif /* INET6 */
519 {
520 nth->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr,
521 htons((u_short)(tlen - sizeof(struct ip) + ip->ip_p)));
522 m->m_pkthdr.csum_flags = CSUM_TCP;
523 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum);
524 }
525#ifdef TCPDEBUG
526 if (tp == NULL || (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
527 tcp_trace(TA_OUTPUT, 0, tp, mtod(m, void *), th, 0);
528#endif
529#ifdef INET6
530 if (isipv6) {
531 (void)ip6_output(m, NULL, ro6, ipflags, NULL, NULL,
532 tp ? tp->t_inpcb : NULL);
533 if (ro6 == &sro6 && ro6->ro_rt) {
534 RTFREE(ro6->ro_rt);
535 ro6->ro_rt = NULL;
536 }
537 } else
538#endif /* INET6 */
539 {
540 (void) ip_output(m, NULL, ro, ipflags, NULL, tp ? tp->t_inpcb : NULL);
541 if (ro == &sro && ro->ro_rt) {
542 RTFREE(ro->ro_rt);
543 ro->ro_rt = NULL;
544 }
545 }
546}
547
548/*
549 * Create a new TCP control block, making an
550 * empty reassembly queue and hooking it to the argument
551 * protocol control block. The `inp' parameter must have
552 * come from the zone allocator set up in tcp_init().
553 */
554struct tcpcb *
555tcp_newtcpcb(inp)
556 struct inpcb *inp;
557{
558 struct tcpcb_mem *tm;
559 struct tcpcb *tp;
560#ifdef INET6
561 int isipv6 = (inp->inp_vflag & INP_IPV6) != 0;
562#endif /* INET6 */
563
564 tm = uma_zalloc(tcpcb_zone, M_NOWAIT | M_ZERO);
565 if (tm == NULL)
566 return (NULL);
567 tp = &tm->tcb;
568 /* LIST_INIT(&tp->t_segq); */ /* XXX covered by M_ZERO */
569 tp->t_maxseg = tp->t_maxopd =
570#ifdef INET6
571 isipv6 ? tcp_v6mssdflt :
572#endif /* INET6 */
573 tcp_mssdflt;
574
575 /* Set up our timeouts. */
576 callout_init(tp->tt_rexmt = &tm->tcpcb_mem_rexmt, 0);
577 callout_init(tp->tt_persist = &tm->tcpcb_mem_persist, 0);
578 callout_init(tp->tt_keep = &tm->tcpcb_mem_keep, 0);
579 callout_init(tp->tt_2msl = &tm->tcpcb_mem_2msl, 0);
580 callout_init(tp->tt_delack = &tm->tcpcb_mem_delack, 0);
581
582 if (tcp_do_rfc1323)
583 tp->t_flags = (TF_REQ_SCALE|TF_REQ_TSTMP);
584 if (tcp_do_rfc1644)
585 tp->t_flags |= TF_REQ_CC;
586 tp->t_inpcb = inp; /* XXX */
587 /*
588 * Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no
589 * rtt estimate. Set rttvar so that srtt + 4 * rttvar gives
590 * reasonable initial retransmit time.
591 */
592 tp->t_srtt = TCPTV_SRTTBASE;
593 tp->t_rttvar = ((TCPTV_RTOBASE - TCPTV_SRTTBASE) << TCP_RTTVAR_SHIFT) / 4;
594 tp->t_rttmin = tcp_rexmit_min;
595 tp->t_rxtcur = TCPTV_RTOBASE;
596 tp->snd_cwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT;
597 tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT;
598 tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT;
599 tp->t_rcvtime = ticks;
600 tp->t_bw_rtttime = ticks;
601 /*
602 * IPv4 TTL initialization is necessary for an IPv6 socket as well,
603 * because the socket may be bound to an IPv6 wildcard address,
604 * which may match an IPv4-mapped IPv6 address.
605 */
606 inp->inp_ip_ttl = ip_defttl;
607 inp->inp_ppcb = (caddr_t)tp;
608 return (tp); /* XXX */
609}
610
611/*
612 * Drop a TCP connection, reporting
613 * the specified error. If connection is synchronized,
614 * then send a RST to peer.
615 */
616struct tcpcb *
617tcp_drop(tp, errno)
618 register struct tcpcb *tp;
619 int errno;
620{
621 struct socket *so = tp->t_inpcb->inp_socket;
622
623 if (TCPS_HAVERCVDSYN(tp->t_state)) {
624 tp->t_state = TCPS_CLOSED;
625 (void) tcp_output(tp);
626 tcpstat.tcps_drops++;
627 } else
628 tcpstat.tcps_conndrops++;
629 if (errno == ETIMEDOUT && tp->t_softerror)
630 errno = tp->t_softerror;
631 so->so_error = errno;
632 return (tcp_close(tp));
633}
634
635static void
636tcp_discardcb(tp)
637 struct tcpcb *tp;
638{
639 struct tseg_qent *q;
640 struct inpcb *inp = tp->t_inpcb;
641 struct socket *so = inp->inp_socket;
642#ifdef INET6
643 int isipv6 = (inp->inp_vflag & INP_IPV6) != 0;
644#endif /* INET6 */
645 struct rtentry *rt;
646 int dosavessthresh;
647
648 /*
649 * Make sure that all of our timers are stopped before we
650 * delete the PCB.
651 */
652 callout_stop(tp->tt_rexmt);
653 callout_stop(tp->tt_persist);
654 callout_stop(tp->tt_keep);
655 callout_stop(tp->tt_2msl);
656 callout_stop(tp->tt_delack);
657
658 /*
659 * If we got enough samples through the srtt filter,
660 * save the rtt and rttvar in the routing entry.
661 * 'Enough' is arbitrarily defined as the 16 samples.
662 * 16 samples is enough for the srtt filter to converge
663 * to within 5% of the correct value; fewer samples and
664 * we could save a very bogus rtt.
665 *
666 * Don't update the default route's characteristics and don't
667 * update anything that the user "locked".
668 */
669 if (tp->t_rttupdated >= 16) {
670 register u_long i = 0;
671#ifdef INET6
672 if (isipv6) {
673 struct sockaddr_in6 *sin6;
674
675 if ((rt = inp->in6p_route.ro_rt) == NULL)
676 goto no_valid_rt;
677 sin6 = (struct sockaddr_in6 *)rt_key(rt);
678 if (IN6_IS_ADDR_UNSPECIFIED(&sin6->sin6_addr))
679 goto no_valid_rt;
680 }
681 else
682#endif /* INET6 */
683 if ((rt = inp->inp_route.ro_rt) == NULL ||
684 ((struct sockaddr_in *)rt_key(rt))->sin_addr.s_addr
685 == INADDR_ANY)
686 goto no_valid_rt;
687
688 if ((rt->rt_rmx.rmx_locks & RTV_RTT) == 0) {
689 i = tp->t_srtt *
690 (RTM_RTTUNIT / (hz * TCP_RTT_SCALE));
691 if (rt->rt_rmx.rmx_rtt && i)
692 /*
693 * filter this update to half the old & half
694 * the new values, converting scale.
695 * See route.h and tcp_var.h for a
696 * description of the scaling constants.
697 */
698 rt->rt_rmx.rmx_rtt =
699 (rt->rt_rmx.rmx_rtt + i) / 2;
700 else
701 rt->rt_rmx.rmx_rtt = i;
702 tcpstat.tcps_cachedrtt++;
703 }
704 if ((rt->rt_rmx.rmx_locks & RTV_RTTVAR) == 0) {
705 i = tp->t_rttvar *
706 (RTM_RTTUNIT / (hz * TCP_RTTVAR_SCALE));
707 if (rt->rt_rmx.rmx_rttvar && i)
708 rt->rt_rmx.rmx_rttvar =
709 (rt->rt_rmx.rmx_rttvar + i) / 2;
710 else
711 rt->rt_rmx.rmx_rttvar = i;
712 tcpstat.tcps_cachedrttvar++;
713 }
714 /*
715 * The old comment here said:
716 * update the pipelimit (ssthresh) if it has been updated
717 * already or if a pipesize was specified & the threshhold
718 * got below half the pipesize. I.e., wait for bad news
719 * before we start updating, then update on both good
720 * and bad news.
721 *
722 * But we want to save the ssthresh even if no pipesize is
723 * specified explicitly in the route, because such
724 * connections still have an implicit pipesize specified
725 * by the global tcp_sendspace. In the absence of a reliable
726 * way to calculate the pipesize, it will have to do.
727 */
728 i = tp->snd_ssthresh;
729 if (rt->rt_rmx.rmx_sendpipe != 0)
730 dosavessthresh = (i < rt->rt_rmx.rmx_sendpipe / 2);
731 else
732 dosavessthresh = (i < so->so_snd.sb_hiwat / 2);
733 if (((rt->rt_rmx.rmx_locks & RTV_SSTHRESH) == 0 &&
734 i != 0 && rt->rt_rmx.rmx_ssthresh != 0)
735 || dosavessthresh) {
736 /*
737 * convert the limit from user data bytes to
738 * packets then to packet data bytes.
739 */
740 i = (i + tp->t_maxseg / 2) / tp->t_maxseg;
741 if (i < 2)
742 i = 2;
743 i *= (u_long)(tp->t_maxseg +
744#ifdef INET6
745 (isipv6 ? sizeof (struct ip6_hdr) +
746 sizeof (struct tcphdr) :
747#endif
748 sizeof (struct tcpiphdr)
749#ifdef INET6
750 )
751#endif
752 );
753 if (rt->rt_rmx.rmx_ssthresh)
754 rt->rt_rmx.rmx_ssthresh =
755 (rt->rt_rmx.rmx_ssthresh + i) / 2;
756 else
757 rt->rt_rmx.rmx_ssthresh = i;
758 tcpstat.tcps_cachedssthresh++;
759 }
760 }
761 no_valid_rt:
762 /* free the reassembly queue, if any */
763 while ((q = LIST_FIRST(&tp->t_segq)) != NULL) {
764 LIST_REMOVE(q, tqe_q);
765 m_freem(q->tqe_m);
766 FREE(q, M_TSEGQ);
767 }
768 inp->inp_ppcb = NULL;
769 tp->t_inpcb = NULL;
770 uma_zfree(tcpcb_zone, tp);
771 soisdisconnected(so);
772}
773
774/*
775 * Close a TCP control block:
776 * discard all space held by the tcp
777 * discard internet protocol block
778 * wake up any sleepers
779 */
780struct tcpcb *
781tcp_close(tp)
782 struct tcpcb *tp;
783{
784 struct inpcb *inp = tp->t_inpcb;
785#ifdef INET6
786 struct socket *so = inp->inp_socket;
787#endif
788
789 tcp_discardcb(tp);
790#ifdef INET6
791 if (INP_CHECK_SOCKAF(so, AF_INET6))
792 in6_pcbdetach(inp);
793 else
794#endif
795 in_pcbdetach(inp);
796 tcpstat.tcps_closed++;
797 return ((struct tcpcb *)0);
798}
799
800void
801tcp_drain()
802{
803 if (do_tcpdrain)
804 {
805 struct inpcb *inpb;
806 struct tcpcb *tcpb;
807 struct tseg_qent *te;
808
809 /*
810 * Walk the tcpbs, if existing, and flush the reassembly queue,
811 * if there is one...
812 * XXX: The "Net/3" implementation doesn't imply that the TCP
813 * reassembly queue should be flushed, but in a situation
814 * where we're really low on mbufs, this is potentially
815 * usefull.
816 */
817 INP_INFO_RLOCK(&tcbinfo);
818 LIST_FOREACH(inpb, tcbinfo.listhead, inp_list) {
819 if (inpb->inp_vflag & INP_TIMEWAIT)
820 continue;
821 INP_LOCK(inpb);
822 if ((tcpb = intotcpcb(inpb))) {
823 while ((te = LIST_FIRST(&tcpb->t_segq))
824 != NULL) {
825 LIST_REMOVE(te, tqe_q);
826 m_freem(te->tqe_m);
827 FREE(te, M_TSEGQ);
828 }
829 }
830 INP_UNLOCK(inpb);
831 }
832 INP_INFO_RUNLOCK(&tcbinfo);
833 }
834}
835
836/*
837 * Notify a tcp user of an asynchronous error;
838 * store error as soft error, but wake up user
839 * (for now, won't do anything until can select for soft error).
840 *
841 * Do not wake up user since there currently is no mechanism for
842 * reporting soft errors (yet - a kqueue filter may be added).
843 */
844static struct inpcb *
845tcp_notify(inp, error)
846 struct inpcb *inp;
847 int error;
848{
849 struct tcpcb *tp = (struct tcpcb *)inp->inp_ppcb;
850
851 /*
852 * Ignore some errors if we are hooked up.
853 * If connection hasn't completed, has retransmitted several times,
854 * and receives a second error, give up now. This is better
855 * than waiting a long time to establish a connection that
856 * can never complete.
857 */
858 if (tp->t_state == TCPS_ESTABLISHED &&
859 (error == EHOSTUNREACH || error == ENETUNREACH ||
860 error == EHOSTDOWN)) {
861 return inp;
862 } else if (tp->t_state < TCPS_ESTABLISHED && tp->t_rxtshift > 3 &&
863 tp->t_softerror) {
864 tcp_drop(tp, error);
865 return (struct inpcb *)0;
866 } else {
867 tp->t_softerror = error;
868 return inp;
869 }
870#if 0
871 wakeup( &so->so_timeo);
872 sorwakeup(so);
873 sowwakeup(so);
874#endif
875}
876
877static int
878tcp_pcblist(SYSCTL_HANDLER_ARGS)
879{
880 int error, i, n, s;
881 struct inpcb *inp, **inp_list;
882 inp_gen_t gencnt;
883 struct xinpgen xig;
884
885 /*
886 * The process of preparing the TCB list is too time-consuming and
887 * resource-intensive to repeat twice on every request.
888 */
889 if (req->oldptr == 0) {
890 n = tcbinfo.ipi_count;
891 req->oldidx = 2 * (sizeof xig)
892 + (n + n/8) * sizeof(struct xtcpcb);
893 return 0;
894 }
895
896 if (req->newptr != 0)
897 return EPERM;
898
899 /*
900 * OK, now we're committed to doing something.
901 */
902 s = splnet();
903 INP_INFO_RLOCK(&tcbinfo);
904 gencnt = tcbinfo.ipi_gencnt;
905 n = tcbinfo.ipi_count;
906 INP_INFO_RUNLOCK(&tcbinfo);
907 splx(s);
908
909 sysctl_wire_old_buffer(req, 2 * (sizeof xig)
910 + n * sizeof(struct xtcpcb));
911
912 xig.xig_len = sizeof xig;
913 xig.xig_count = n;
914 xig.xig_gen = gencnt;
915 xig.xig_sogen = so_gencnt;
916 error = SYSCTL_OUT(req, &xig, sizeof xig);
917 if (error)
918 return error;
919
920 inp_list = malloc(n * sizeof *inp_list, M_TEMP, M_WAITOK);
921 if (inp_list == 0)
922 return ENOMEM;
923
924 s = splnet();
925 INP_INFO_RLOCK(&tcbinfo);
926 for (inp = LIST_FIRST(tcbinfo.listhead), i = 0; inp && i < n;
927 inp = LIST_NEXT(inp, inp_list)) {
928 INP_LOCK(inp);
929 if (inp->inp_gencnt <= gencnt) {
930 /*
931 * XXX: This use of cr_cansee(), introduced with
932 * TCP state changes, is not quite right, but for
933 * now, better than nothing.
934 */
935 if (inp->inp_vflag & INP_TIMEWAIT)
936 error = cr_cansee(req->td->td_ucred,
937 intotw(inp)->tw_cred);
938 else
939 error = cr_canseesocket(req->td->td_ucred,
940 inp->inp_socket);
941 if (error == 0)
942 inp_list[i++] = inp;
943 }
944 INP_UNLOCK(inp);
945 }
946 INP_INFO_RUNLOCK(&tcbinfo);
947 splx(s);
948 n = i;
949
950 error = 0;
951 for (i = 0; i < n; i++) {
952 inp = inp_list[i];
953 if (inp->inp_gencnt <= gencnt) {
954 struct xtcpcb xt;
955 caddr_t inp_ppcb;
956 xt.xt_len = sizeof xt;
957 /* XXX should avoid extra copy */
958 bcopy(inp, &xt.xt_inp, sizeof *inp);
959 inp_ppcb = inp->inp_ppcb;
960 if (inp_ppcb == NULL)
961 bzero((char *) &xt.xt_tp, sizeof xt.xt_tp);
962 else if (inp->inp_vflag & INP_TIMEWAIT) {
963 bzero((char *) &xt.xt_tp, sizeof xt.xt_tp);
964 xt.xt_tp.t_state = TCPS_TIME_WAIT;
965 } else
966 bcopy(inp_ppcb, &xt.xt_tp, sizeof xt.xt_tp);
967 if (inp->inp_socket)
968 sotoxsocket(inp->inp_socket, &xt.xt_socket);
969 else {
970 bzero(&xt.xt_socket, sizeof xt.xt_socket);
971 xt.xt_socket.xso_protocol = IPPROTO_TCP;
972 }
973 xt.xt_inp.inp_gencnt = inp->inp_gencnt;
974 error = SYSCTL_OUT(req, &xt, sizeof xt);
975 }
976 }
977 if (!error) {
978 /*
979 * Give the user an updated idea of our state.
980 * If the generation differs from what we told
981 * her before, she knows that something happened
982 * while we were processing this request, and it
983 * might be necessary to retry.
984 */
985 s = splnet();
986 INP_INFO_RLOCK(&tcbinfo);
987 xig.xig_gen = tcbinfo.ipi_gencnt;
988 xig.xig_sogen = so_gencnt;
989 xig.xig_count = tcbinfo.ipi_count;
990 INP_INFO_RUNLOCK(&tcbinfo);
991 splx(s);
992 error = SYSCTL_OUT(req, &xig, sizeof xig);
993 }
994 free(inp_list, M_TEMP);
995 return error;
996}
997
998SYSCTL_PROC(_net_inet_tcp, TCPCTL_PCBLIST, pcblist, CTLFLAG_RD, 0, 0,
999 tcp_pcblist, "S,xtcpcb", "List of active TCP connections");
1000
1001static int
1002tcp_getcred(SYSCTL_HANDLER_ARGS)
1003{
1004 struct xucred xuc;
1005 struct sockaddr_in addrs[2];
1006 struct inpcb *inp;
1007 int error, s;
1008
1009 error = suser_cred(req->td->td_ucred, PRISON_ROOT);
1010 if (error)
1011 return (error);
1012 error = SYSCTL_IN(req, addrs, sizeof(addrs));
1013 if (error)
1014 return (error);
1015 s = splnet();
1016 INP_INFO_RLOCK(&tcbinfo);
1017 inp = in_pcblookup_hash(&tcbinfo, addrs[1].sin_addr, addrs[1].sin_port,
1018 addrs[0].sin_addr, addrs[0].sin_port, 0, NULL);
1019 if (inp == NULL) {
1020 error = ENOENT;
1021 goto outunlocked;
1022 }
1023 INP_LOCK(inp);
1024 if (inp->inp_socket == NULL) {
1025 error = ENOENT;
1026 goto out;
1027 }
1028 error = cr_canseesocket(req->td->td_ucred, inp->inp_socket);
1029 if (error)
1030 goto out;
1031 cru2x(inp->inp_socket->so_cred, &xuc);
1032out:
1033 INP_UNLOCK(inp);
1034outunlocked:
1035 INP_INFO_RUNLOCK(&tcbinfo);
1036 splx(s);
1037 if (error == 0)
1038 error = SYSCTL_OUT(req, &xuc, sizeof(struct xucred));
1039 return (error);
1040}
1041
1042SYSCTL_PROC(_net_inet_tcp, OID_AUTO, getcred,
1043 CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_PRISON, 0, 0,
1044 tcp_getcred, "S,xucred", "Get the xucred of a TCP connection");
1045
1046#ifdef INET6
1047static int
1048tcp6_getcred(SYSCTL_HANDLER_ARGS)
1049{
1050 struct xucred xuc;
1051 struct sockaddr_in6 addrs[2];
1052 struct inpcb *inp;
1053 int error, s, mapped = 0;
1054
1055 error = suser_cred(req->td->td_ucred, PRISON_ROOT);
1056 if (error)
1057 return (error);
1058 error = SYSCTL_IN(req, addrs, sizeof(addrs));
1059 if (error)
1060 return (error);
1061 if (IN6_IS_ADDR_V4MAPPED(&addrs[0].sin6_addr)) {
1062 if (IN6_IS_ADDR_V4MAPPED(&addrs[1].sin6_addr))
1063 mapped = 1;
1064 else
1065 return (EINVAL);
1066 }
1067 s = splnet();
1068 INP_INFO_RLOCK(&tcbinfo);
1069 if (mapped == 1)
1070 inp = in_pcblookup_hash(&tcbinfo,
1071 *(struct in_addr *)&addrs[1].sin6_addr.s6_addr[12],
1072 addrs[1].sin6_port,
1073 *(struct in_addr *)&addrs[0].sin6_addr.s6_addr[12],
1074 addrs[0].sin6_port,
1075 0, NULL);
1076 else
1077 inp = in6_pcblookup_hash(&tcbinfo, &addrs[1].sin6_addr,
1078 addrs[1].sin6_port,
1079 &addrs[0].sin6_addr, addrs[0].sin6_port,
1080 0, NULL);
1081 if (inp == NULL) {
1082 error = ENOENT;
1083 goto outunlocked;
1084 }
1085 INP_LOCK(inp);
1086 if (inp->inp_socket == NULL) {
1087 error = ENOENT;
1088 goto out;
1089 }
1090 error = cr_canseesocket(req->td->td_ucred, inp->inp_socket);
1091 if (error)
1092 goto out;
1093 cru2x(inp->inp_socket->so_cred, &xuc);
1094out:
1095 INP_UNLOCK(inp);
1096outunlocked:
1097 INP_INFO_RUNLOCK(&tcbinfo);
1098 splx(s);
1099 if (error == 0)
1100 error = SYSCTL_OUT(req, &xuc, sizeof(struct xucred));
1101 return (error);
1102}
1103
1104SYSCTL_PROC(_net_inet6_tcp6, OID_AUTO, getcred,
1105 CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_PRISON, 0, 0,
1106 tcp6_getcred, "S,xucred", "Get the xucred of a TCP6 connection");
1107#endif
1108
1109
1110void
1111tcp_ctlinput(cmd, sa, vip)
1112 int cmd;
1113 struct sockaddr *sa;
1114 void *vip;
1115{
1116 struct ip *ip = vip;
1117 struct tcphdr *th;
1118 struct in_addr faddr;
1119 struct inpcb *inp;
1120 struct tcpcb *tp;
1121 struct inpcb *(*notify)(struct inpcb *, int) = tcp_notify;
1122 tcp_seq icmp_seq;
1123 int s;
1124
1125 faddr = ((struct sockaddr_in *)sa)->sin_addr;
1126 if (sa->sa_family != AF_INET || faddr.s_addr == INADDR_ANY)
1127 return;
1128
1129 if (cmd == PRC_QUENCH)
1130 notify = tcp_quench;
1131 else if (icmp_may_rst && (cmd == PRC_UNREACH_ADMIN_PROHIB ||
1132 cmd == PRC_UNREACH_PORT || cmd == PRC_TIMXCEED_INTRANS) && ip)
1133 notify = tcp_drop_syn_sent;
1134 else if (cmd == PRC_MSGSIZE)
1135 notify = tcp_mtudisc;
1136 else if (PRC_IS_REDIRECT(cmd)) {
1137 ip = 0;
1138 notify = in_rtchange;
1139 } else if (cmd == PRC_HOSTDEAD)
1140 ip = 0;
| 35 */
36
37#include "opt_compat.h"
38#include "opt_inet6.h"
39#include "opt_ipsec.h"
40#include "opt_mac.h"
41#include "opt_tcpdebug.h"
42
43#include <sys/param.h>
44#include <sys/systm.h>
45#include <sys/callout.h>
46#include <sys/kernel.h>
47#include <sys/sysctl.h>
48#include <sys/mac.h>
49#include <sys/malloc.h>
50#include <sys/mbuf.h>
51#ifdef INET6
52#include <sys/domain.h>
53#endif
54#include <sys/proc.h>
55#include <sys/socket.h>
56#include <sys/socketvar.h>
57#include <sys/protosw.h>
58#include <sys/random.h>
59
60#include <vm/uma.h>
61
62#include <net/route.h>
63#include <net/if.h>
64
65#include <netinet/in.h>
66#include <netinet/in_systm.h>
67#include <netinet/ip.h>
68#ifdef INET6
69#include <netinet/ip6.h>
70#endif
71#include <netinet/in_pcb.h>
72#ifdef INET6
73#include <netinet6/in6_pcb.h>
74#endif
75#include <netinet/in_var.h>
76#include <netinet/ip_var.h>
77#ifdef INET6
78#include <netinet6/ip6_var.h>
79#endif
80#include <netinet/tcp.h>
81#include <netinet/tcp_fsm.h>
82#include <netinet/tcp_seq.h>
83#include <netinet/tcp_timer.h>
84#include <netinet/tcp_var.h>
85#ifdef INET6
86#include <netinet6/tcp6_var.h>
87#endif
88#include <netinet/tcpip.h>
89#ifdef TCPDEBUG
90#include <netinet/tcp_debug.h>
91#endif
92#include <netinet6/ip6protosw.h>
93
94#ifdef IPSEC
95#include <netinet6/ipsec.h>
96#ifdef INET6
97#include <netinet6/ipsec6.h>
98#endif
99#endif /*IPSEC*/
100
101#ifdef FAST_IPSEC
102#include <netipsec/ipsec.h>
103#ifdef INET6
104#include <netipsec/ipsec6.h>
105#endif
106#define IPSEC
107#endif /*FAST_IPSEC*/
108
109#include <machine/in_cksum.h>
110#include <sys/md5.h>
111
112int tcp_mssdflt = TCP_MSS;
113SYSCTL_INT(_net_inet_tcp, TCPCTL_MSSDFLT, mssdflt, CTLFLAG_RW,
114 &tcp_mssdflt , 0, "Default TCP Maximum Segment Size");
115
116#ifdef INET6
117int tcp_v6mssdflt = TCP6_MSS;
118SYSCTL_INT(_net_inet_tcp, TCPCTL_V6MSSDFLT, v6mssdflt,
119 CTLFLAG_RW, &tcp_v6mssdflt , 0,
120 "Default TCP Maximum Segment Size for IPv6");
121#endif
122
123#if 0
124static int tcp_rttdflt = TCPTV_SRTTDFLT / PR_SLOWHZ;
125SYSCTL_INT(_net_inet_tcp, TCPCTL_RTTDFLT, rttdflt, CTLFLAG_RW,
126 &tcp_rttdflt , 0, "Default maximum TCP Round Trip Time");
127#endif
128
129int tcp_do_rfc1323 = 1;
130SYSCTL_INT(_net_inet_tcp, TCPCTL_DO_RFC1323, rfc1323, CTLFLAG_RW,
131 &tcp_do_rfc1323 , 0, "Enable rfc1323 (high performance TCP) extensions");
132
133int tcp_do_rfc1644 = 0;
134SYSCTL_INT(_net_inet_tcp, TCPCTL_DO_RFC1644, rfc1644, CTLFLAG_RW,
135 &tcp_do_rfc1644 , 0, "Enable rfc1644 (TTCP) extensions");
136
137static int tcp_tcbhashsize = 0;
138SYSCTL_INT(_net_inet_tcp, OID_AUTO, tcbhashsize, CTLFLAG_RD,
139 &tcp_tcbhashsize, 0, "Size of TCP control-block hashtable");
140
141static int do_tcpdrain = 1;
142SYSCTL_INT(_net_inet_tcp, OID_AUTO, do_tcpdrain, CTLFLAG_RW, &do_tcpdrain, 0,
143 "Enable tcp_drain routine for extra help when low on mbufs");
144
145SYSCTL_INT(_net_inet_tcp, OID_AUTO, pcbcount, CTLFLAG_RD,
146 &tcbinfo.ipi_count, 0, "Number of active PCBs");
147
148static int icmp_may_rst = 1;
149SYSCTL_INT(_net_inet_tcp, OID_AUTO, icmp_may_rst, CTLFLAG_RW, &icmp_may_rst, 0,
150 "Certain ICMP unreachable messages may abort connections in SYN_SENT");
151
152static int tcp_isn_reseed_interval = 0;
153SYSCTL_INT(_net_inet_tcp, OID_AUTO, isn_reseed_interval, CTLFLAG_RW,
154 &tcp_isn_reseed_interval, 0, "Seconds between reseeding of ISN secret");
155
156/*
157 * TCP bandwidth limiting sysctls. Note that the default lower bound of
158 * 1024 exists only for debugging. A good production default would be
159 * something like 6100.
160 */
161static int tcp_inflight_enable = 0;
162SYSCTL_INT(_net_inet_tcp, OID_AUTO, inflight_enable, CTLFLAG_RW,
163 &tcp_inflight_enable, 0, "Enable automatic TCP inflight data limiting");
164
165static int tcp_inflight_debug = 0;
166SYSCTL_INT(_net_inet_tcp, OID_AUTO, inflight_debug, CTLFLAG_RW,
167 &tcp_inflight_debug, 0, "Debug TCP inflight calculations");
168
169static int tcp_inflight_min = 6144;
170SYSCTL_INT(_net_inet_tcp, OID_AUTO, inflight_min, CTLFLAG_RW,
171 &tcp_inflight_min, 0, "Lower-bound for TCP inflight window");
172
173static int tcp_inflight_max = TCP_MAXWIN << TCP_MAX_WINSHIFT;
174SYSCTL_INT(_net_inet_tcp, OID_AUTO, inflight_max, CTLFLAG_RW,
175 &tcp_inflight_max, 0, "Upper-bound for TCP inflight window");
176static int tcp_inflight_stab = 20;
177SYSCTL_INT(_net_inet_tcp, OID_AUTO, inflight_stab, CTLFLAG_RW,
178 &tcp_inflight_stab, 0, "Inflight Algorithm Stabilization 20 = 2 packets");
179
180static void tcp_cleartaocache(void);
181static struct inpcb *tcp_notify(struct inpcb *, int);
182static void tcp_discardcb(struct tcpcb *);
183
184/*
185 * Target size of TCP PCB hash tables. Must be a power of two.
186 *
187 * Note that this can be overridden by the kernel environment
188 * variable net.inet.tcp.tcbhashsize
189 */
190#ifndef TCBHASHSIZE
191#define TCBHASHSIZE 512
192#endif
193
194/*
195 * XXX
196 * Callouts should be moved into struct tcp directly. They are currently
197 * separate becuase the tcpcb structure is exported to userland for sysctl
198 * parsing purposes, which do not know about callouts.
199 */
200struct tcpcb_mem {
201 struct tcpcb tcb;
202 struct callout tcpcb_mem_rexmt, tcpcb_mem_persist, tcpcb_mem_keep;
203 struct callout tcpcb_mem_2msl, tcpcb_mem_delack;
204};
205
206static uma_zone_t tcpcb_zone;
207static uma_zone_t tcptw_zone;
208
209/*
210 * Tcp initialization
211 */
212void
213tcp_init()
214{
215 int hashsize = TCBHASHSIZE;
216
217 tcp_ccgen = 1;
218 tcp_cleartaocache();
219
220 tcp_delacktime = TCPTV_DELACK;
221 tcp_keepinit = TCPTV_KEEP_INIT;
222 tcp_keepidle = TCPTV_KEEP_IDLE;
223 tcp_keepintvl = TCPTV_KEEPINTVL;
224 tcp_maxpersistidle = TCPTV_KEEP_IDLE;
225 tcp_msl = TCPTV_MSL;
226 tcp_rexmit_min = TCPTV_MIN;
227 tcp_rexmit_slop = TCPTV_CPU_VAR;
228
229 INP_INFO_LOCK_INIT(&tcbinfo, "tcp");
230 LIST_INIT(&tcb);
231 tcbinfo.listhead = &tcb;
232 TUNABLE_INT_FETCH("net.inet.tcp.tcbhashsize", &hashsize);
233 if (!powerof2(hashsize)) {
234 printf("WARNING: TCB hash size not a power of 2\n");
235 hashsize = 512; /* safe default */
236 }
237 tcp_tcbhashsize = hashsize;
238 tcbinfo.hashbase = hashinit(hashsize, M_PCB, &tcbinfo.hashmask);
239 tcbinfo.porthashbase = hashinit(hashsize, M_PCB,
240 &tcbinfo.porthashmask);
241 tcbinfo.ipi_zone = uma_zcreate("inpcb", sizeof(struct inpcb),
242 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
243 uma_zone_set_max(tcbinfo.ipi_zone, maxsockets);
244#ifdef INET6
245#define TCP_MINPROTOHDR (sizeof(struct ip6_hdr) + sizeof(struct tcphdr))
246#else /* INET6 */
247#define TCP_MINPROTOHDR (sizeof(struct tcpiphdr))
248#endif /* INET6 */
249 if (max_protohdr < TCP_MINPROTOHDR)
250 max_protohdr = TCP_MINPROTOHDR;
251 if (max_linkhdr + TCP_MINPROTOHDR > MHLEN)
252 panic("tcp_init");
253#undef TCP_MINPROTOHDR
254 /*
255 * These have to be type stable for the benefit of the timers.
256 */
257 tcpcb_zone = uma_zcreate("tcpcb", sizeof(struct tcpcb_mem),
258 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
259 uma_zone_set_max(tcpcb_zone, maxsockets);
260 tcptw_zone = uma_zcreate("tcptw", sizeof(struct tcptw),
261 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
262 uma_zone_set_max(tcptw_zone, maxsockets);
263 tcp_timer_init();
264 syncache_init();
265}
266
267/*
268 * Fill in the IP and TCP headers for an outgoing packet, given the tcpcb.
269 * tcp_template used to store this data in mbufs, but we now recopy it out
270 * of the tcpcb each time to conserve mbufs.
271 */
272void
273tcpip_fillheaders(inp, ip_ptr, tcp_ptr)
274 struct inpcb *inp;
275 void *ip_ptr;
276 void *tcp_ptr;
277{
278 struct tcphdr *th = (struct tcphdr *)tcp_ptr;
279
280#ifdef INET6
281 if ((inp->inp_vflag & INP_IPV6) != 0) {
282 struct ip6_hdr *ip6;
283
284 ip6 = (struct ip6_hdr *)ip_ptr;
285 ip6->ip6_flow = (ip6->ip6_flow & ~IPV6_FLOWINFO_MASK) |
286 (inp->in6p_flowinfo & IPV6_FLOWINFO_MASK);
287 ip6->ip6_vfc = (ip6->ip6_vfc & ~IPV6_VERSION_MASK) |
288 (IPV6_VERSION & IPV6_VERSION_MASK);
289 ip6->ip6_nxt = IPPROTO_TCP;
290 ip6->ip6_plen = sizeof(struct tcphdr);
291 ip6->ip6_src = inp->in6p_laddr;
292 ip6->ip6_dst = inp->in6p_faddr;
293 } else
294#endif
295 {
296 struct ip *ip;
297
298 ip = (struct ip *)ip_ptr;
299 ip->ip_v = IPVERSION;
300 ip->ip_hl = 5;
301 ip->ip_tos = inp->inp_ip_tos;
302 ip->ip_len = 0;
303 ip->ip_id = 0;
304 ip->ip_off = 0;
305 ip->ip_ttl = inp->inp_ip_ttl;
306 ip->ip_sum = 0;
307 ip->ip_p = IPPROTO_TCP;
308 ip->ip_src = inp->inp_laddr;
309 ip->ip_dst = inp->inp_faddr;
310 }
311 th->th_sport = inp->inp_lport;
312 th->th_dport = inp->inp_fport;
313 th->th_seq = 0;
314 th->th_ack = 0;
315 th->th_x2 = 0;
316 th->th_off = 5;
317 th->th_flags = 0;
318 th->th_win = 0;
319 th->th_urp = 0;
320 th->th_sum = 0; /* in_pseudo() is called later for ipv4 */
321}
322
323/*
324 * Create template to be used to send tcp packets on a connection.
325 * Allocates an mbuf and fills in a skeletal tcp/ip header. The only
326 * use for this function is in keepalives, which use tcp_respond.
327 */
328struct tcptemp *
329tcpip_maketemplate(inp)
330 struct inpcb *inp;
331{
332 struct mbuf *m;
333 struct tcptemp *n;
334
335 m = m_get(M_DONTWAIT, MT_HEADER);
336 if (m == NULL)
337 return (0);
338 m->m_len = sizeof(struct tcptemp);
339 n = mtod(m, struct tcptemp *);
340
341 tcpip_fillheaders(inp, (void *)&n->tt_ipgen, (void *)&n->tt_t);
342 return (n);
343}
344
345/*
346 * Send a single message to the TCP at address specified by
347 * the given TCP/IP header. If m == 0, then we make a copy
348 * of the tcpiphdr at ti and send directly to the addressed host.
349 * This is used to force keep alive messages out using the TCP
350 * template for a connection. If flags are given then we send
351 * a message back to the TCP which originated the * segment ti,
352 * and discard the mbuf containing it and any other attached mbufs.
353 *
354 * In any case the ack and sequence number of the transmitted
355 * segment are as specified by the parameters.
356 *
357 * NOTE: If m != NULL, then ti must point to *inside* the mbuf.
358 */
359void
360tcp_respond(tp, ipgen, th, m, ack, seq, flags)
361 struct tcpcb *tp;
362 void *ipgen;
363 register struct tcphdr *th;
364 register struct mbuf *m;
365 tcp_seq ack, seq;
366 int flags;
367{
368 register int tlen;
369 int win = 0;
370 struct route *ro = 0;
371 struct route sro;
372 struct ip *ip;
373 struct tcphdr *nth;
374#ifdef INET6
375 struct route_in6 *ro6 = 0;
376 struct route_in6 sro6;
377 struct ip6_hdr *ip6;
378 int isipv6;
379#endif /* INET6 */
380 int ipflags = 0;
381
382 KASSERT(tp != NULL || m != NULL, ("tcp_respond: tp and m both NULL"));
383
384#ifdef INET6
385 isipv6 = ((struct ip *)ipgen)->ip_v == 6;
386 ip6 = ipgen;
387#endif /* INET6 */
388 ip = ipgen;
389
390 if (tp) {
391 if (!(flags & TH_RST)) {
392 win = sbspace(&tp->t_inpcb->inp_socket->so_rcv);
393 if (win > (long)TCP_MAXWIN << tp->rcv_scale)
394 win = (long)TCP_MAXWIN << tp->rcv_scale;
395 }
396#ifdef INET6
397 if (isipv6)
398 ro6 = &tp->t_inpcb->in6p_route;
399 else
400#endif /* INET6 */
401 ro = &tp->t_inpcb->inp_route;
402 } else {
403#ifdef INET6
404 if (isipv6) {
405 ro6 = &sro6;
406 bzero(ro6, sizeof *ro6);
407 } else
408#endif /* INET6 */
409 {
410 ro = &sro;
411 bzero(ro, sizeof *ro);
412 }
413 }
414 if (m == 0) {
415 m = m_gethdr(M_DONTWAIT, MT_HEADER);
416 if (m == NULL)
417 return;
418 tlen = 0;
419 m->m_data += max_linkhdr;
420#ifdef INET6
421 if (isipv6) {
422 bcopy((caddr_t)ip6, mtod(m, caddr_t),
423 sizeof(struct ip6_hdr));
424 ip6 = mtod(m, struct ip6_hdr *);
425 nth = (struct tcphdr *)(ip6 + 1);
426 } else
427#endif /* INET6 */
428 {
429 bcopy((caddr_t)ip, mtod(m, caddr_t), sizeof(struct ip));
430 ip = mtod(m, struct ip *);
431 nth = (struct tcphdr *)(ip + 1);
432 }
433 bcopy((caddr_t)th, (caddr_t)nth, sizeof(struct tcphdr));
434 flags = TH_ACK;
435 } else {
436 m_freem(m->m_next);
437 m->m_next = 0;
438 m->m_data = (caddr_t)ipgen;
439 /* m_len is set later */
440 tlen = 0;
441#define xchg(a,b,type) { type t; t=a; a=b; b=t; }
442#ifdef INET6
443 if (isipv6) {
444 xchg(ip6->ip6_dst, ip6->ip6_src, struct in6_addr);
445 nth = (struct tcphdr *)(ip6 + 1);
446 } else
447#endif /* INET6 */
448 {
449 xchg(ip->ip_dst.s_addr, ip->ip_src.s_addr, n_long);
450 nth = (struct tcphdr *)(ip + 1);
451 }
452 if (th != nth) {
453 /*
454 * this is usually a case when an extension header
455 * exists between the IPv6 header and the
456 * TCP header.
457 */
458 nth->th_sport = th->th_sport;
459 nth->th_dport = th->th_dport;
460 }
461 xchg(nth->th_dport, nth->th_sport, n_short);
462#undef xchg
463 }
464#ifdef INET6
465 if (isipv6) {
466 ip6->ip6_flow = 0;
467 ip6->ip6_vfc = IPV6_VERSION;
468 ip6->ip6_nxt = IPPROTO_TCP;
469 ip6->ip6_plen = htons((u_short)(sizeof (struct tcphdr) +
470 tlen));
471 tlen += sizeof (struct ip6_hdr) + sizeof (struct tcphdr);
472 } else
473#endif
474 {
475 tlen += sizeof (struct tcpiphdr);
476 ip->ip_len = tlen;
477 ip->ip_ttl = ip_defttl;
478 }
479 m->m_len = tlen;
480 m->m_pkthdr.len = tlen;
481 m->m_pkthdr.rcvif = (struct ifnet *) 0;
482#ifdef MAC
483 if (tp != NULL && tp->t_inpcb != NULL) {
484 /*
485 * Packet is associated with a socket, so allow the
486 * label of the response to reflect the socket label.
487 */
488 mac_create_mbuf_from_socket(tp->t_inpcb->inp_socket, m);
489 } else {
490 /*
491 * Packet is not associated with a socket, so possibly
492 * update the label in place.
493 */
494 mac_reflect_mbuf_tcp(m);
495 }
496#endif
497 nth->th_seq = htonl(seq);
498 nth->th_ack = htonl(ack);
499 nth->th_x2 = 0;
500 nth->th_off = sizeof (struct tcphdr) >> 2;
501 nth->th_flags = flags;
502 if (tp)
503 nth->th_win = htons((u_short) (win >> tp->rcv_scale));
504 else
505 nth->th_win = htons((u_short)win);
506 nth->th_urp = 0;
507#ifdef INET6
508 if (isipv6) {
509 nth->th_sum = 0;
510 nth->th_sum = in6_cksum(m, IPPROTO_TCP,
511 sizeof(struct ip6_hdr),
512 tlen - sizeof(struct ip6_hdr));
513 ip6->ip6_hlim = in6_selecthlim(tp ? tp->t_inpcb : NULL,
514 ro6 && ro6->ro_rt ?
515 ro6->ro_rt->rt_ifp :
516 NULL);
517 } else
518#endif /* INET6 */
519 {
520 nth->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr,
521 htons((u_short)(tlen - sizeof(struct ip) + ip->ip_p)));
522 m->m_pkthdr.csum_flags = CSUM_TCP;
523 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum);
524 }
525#ifdef TCPDEBUG
526 if (tp == NULL || (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
527 tcp_trace(TA_OUTPUT, 0, tp, mtod(m, void *), th, 0);
528#endif
529#ifdef INET6
530 if (isipv6) {
531 (void)ip6_output(m, NULL, ro6, ipflags, NULL, NULL,
532 tp ? tp->t_inpcb : NULL);
533 if (ro6 == &sro6 && ro6->ro_rt) {
534 RTFREE(ro6->ro_rt);
535 ro6->ro_rt = NULL;
536 }
537 } else
538#endif /* INET6 */
539 {
540 (void) ip_output(m, NULL, ro, ipflags, NULL, tp ? tp->t_inpcb : NULL);
541 if (ro == &sro && ro->ro_rt) {
542 RTFREE(ro->ro_rt);
543 ro->ro_rt = NULL;
544 }
545 }
546}
547
548/*
549 * Create a new TCP control block, making an
550 * empty reassembly queue and hooking it to the argument
551 * protocol control block. The `inp' parameter must have
552 * come from the zone allocator set up in tcp_init().
553 */
554struct tcpcb *
555tcp_newtcpcb(inp)
556 struct inpcb *inp;
557{
558 struct tcpcb_mem *tm;
559 struct tcpcb *tp;
560#ifdef INET6
561 int isipv6 = (inp->inp_vflag & INP_IPV6) != 0;
562#endif /* INET6 */
563
564 tm = uma_zalloc(tcpcb_zone, M_NOWAIT | M_ZERO);
565 if (tm == NULL)
566 return (NULL);
567 tp = &tm->tcb;
568 /* LIST_INIT(&tp->t_segq); */ /* XXX covered by M_ZERO */
569 tp->t_maxseg = tp->t_maxopd =
570#ifdef INET6
571 isipv6 ? tcp_v6mssdflt :
572#endif /* INET6 */
573 tcp_mssdflt;
574
575 /* Set up our timeouts. */
576 callout_init(tp->tt_rexmt = &tm->tcpcb_mem_rexmt, 0);
577 callout_init(tp->tt_persist = &tm->tcpcb_mem_persist, 0);
578 callout_init(tp->tt_keep = &tm->tcpcb_mem_keep, 0);
579 callout_init(tp->tt_2msl = &tm->tcpcb_mem_2msl, 0);
580 callout_init(tp->tt_delack = &tm->tcpcb_mem_delack, 0);
581
582 if (tcp_do_rfc1323)
583 tp->t_flags = (TF_REQ_SCALE|TF_REQ_TSTMP);
584 if (tcp_do_rfc1644)
585 tp->t_flags |= TF_REQ_CC;
586 tp->t_inpcb = inp; /* XXX */
587 /*
588 * Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no
589 * rtt estimate. Set rttvar so that srtt + 4 * rttvar gives
590 * reasonable initial retransmit time.
591 */
592 tp->t_srtt = TCPTV_SRTTBASE;
593 tp->t_rttvar = ((TCPTV_RTOBASE - TCPTV_SRTTBASE) << TCP_RTTVAR_SHIFT) / 4;
594 tp->t_rttmin = tcp_rexmit_min;
595 tp->t_rxtcur = TCPTV_RTOBASE;
596 tp->snd_cwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT;
597 tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT;
598 tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT;
599 tp->t_rcvtime = ticks;
600 tp->t_bw_rtttime = ticks;
601 /*
602 * IPv4 TTL initialization is necessary for an IPv6 socket as well,
603 * because the socket may be bound to an IPv6 wildcard address,
604 * which may match an IPv4-mapped IPv6 address.
605 */
606 inp->inp_ip_ttl = ip_defttl;
607 inp->inp_ppcb = (caddr_t)tp;
608 return (tp); /* XXX */
609}
610
611/*
612 * Drop a TCP connection, reporting
613 * the specified error. If connection is synchronized,
614 * then send a RST to peer.
615 */
616struct tcpcb *
617tcp_drop(tp, errno)
618 register struct tcpcb *tp;
619 int errno;
620{
621 struct socket *so = tp->t_inpcb->inp_socket;
622
623 if (TCPS_HAVERCVDSYN(tp->t_state)) {
624 tp->t_state = TCPS_CLOSED;
625 (void) tcp_output(tp);
626 tcpstat.tcps_drops++;
627 } else
628 tcpstat.tcps_conndrops++;
629 if (errno == ETIMEDOUT && tp->t_softerror)
630 errno = tp->t_softerror;
631 so->so_error = errno;
632 return (tcp_close(tp));
633}
634
635static void
636tcp_discardcb(tp)
637 struct tcpcb *tp;
638{
639 struct tseg_qent *q;
640 struct inpcb *inp = tp->t_inpcb;
641 struct socket *so = inp->inp_socket;
642#ifdef INET6
643 int isipv6 = (inp->inp_vflag & INP_IPV6) != 0;
644#endif /* INET6 */
645 struct rtentry *rt;
646 int dosavessthresh;
647
648 /*
649 * Make sure that all of our timers are stopped before we
650 * delete the PCB.
651 */
652 callout_stop(tp->tt_rexmt);
653 callout_stop(tp->tt_persist);
654 callout_stop(tp->tt_keep);
655 callout_stop(tp->tt_2msl);
656 callout_stop(tp->tt_delack);
657
658 /*
659 * If we got enough samples through the srtt filter,
660 * save the rtt and rttvar in the routing entry.
661 * 'Enough' is arbitrarily defined as the 16 samples.
662 * 16 samples is enough for the srtt filter to converge
663 * to within 5% of the correct value; fewer samples and
664 * we could save a very bogus rtt.
665 *
666 * Don't update the default route's characteristics and don't
667 * update anything that the user "locked".
668 */
669 if (tp->t_rttupdated >= 16) {
670 register u_long i = 0;
671#ifdef INET6
672 if (isipv6) {
673 struct sockaddr_in6 *sin6;
674
675 if ((rt = inp->in6p_route.ro_rt) == NULL)
676 goto no_valid_rt;
677 sin6 = (struct sockaddr_in6 *)rt_key(rt);
678 if (IN6_IS_ADDR_UNSPECIFIED(&sin6->sin6_addr))
679 goto no_valid_rt;
680 }
681 else
682#endif /* INET6 */
683 if ((rt = inp->inp_route.ro_rt) == NULL ||
684 ((struct sockaddr_in *)rt_key(rt))->sin_addr.s_addr
685 == INADDR_ANY)
686 goto no_valid_rt;
687
688 if ((rt->rt_rmx.rmx_locks & RTV_RTT) == 0) {
689 i = tp->t_srtt *
690 (RTM_RTTUNIT / (hz * TCP_RTT_SCALE));
691 if (rt->rt_rmx.rmx_rtt && i)
692 /*
693 * filter this update to half the old & half
694 * the new values, converting scale.
695 * See route.h and tcp_var.h for a
696 * description of the scaling constants.
697 */
698 rt->rt_rmx.rmx_rtt =
699 (rt->rt_rmx.rmx_rtt + i) / 2;
700 else
701 rt->rt_rmx.rmx_rtt = i;
702 tcpstat.tcps_cachedrtt++;
703 }
704 if ((rt->rt_rmx.rmx_locks & RTV_RTTVAR) == 0) {
705 i = tp->t_rttvar *
706 (RTM_RTTUNIT / (hz * TCP_RTTVAR_SCALE));
707 if (rt->rt_rmx.rmx_rttvar && i)
708 rt->rt_rmx.rmx_rttvar =
709 (rt->rt_rmx.rmx_rttvar + i) / 2;
710 else
711 rt->rt_rmx.rmx_rttvar = i;
712 tcpstat.tcps_cachedrttvar++;
713 }
714 /*
715 * The old comment here said:
716 * update the pipelimit (ssthresh) if it has been updated
717 * already or if a pipesize was specified & the threshhold
718 * got below half the pipesize. I.e., wait for bad news
719 * before we start updating, then update on both good
720 * and bad news.
721 *
722 * But we want to save the ssthresh even if no pipesize is
723 * specified explicitly in the route, because such
724 * connections still have an implicit pipesize specified
725 * by the global tcp_sendspace. In the absence of a reliable
726 * way to calculate the pipesize, it will have to do.
727 */
728 i = tp->snd_ssthresh;
729 if (rt->rt_rmx.rmx_sendpipe != 0)
730 dosavessthresh = (i < rt->rt_rmx.rmx_sendpipe / 2);
731 else
732 dosavessthresh = (i < so->so_snd.sb_hiwat / 2);
733 if (((rt->rt_rmx.rmx_locks & RTV_SSTHRESH) == 0 &&
734 i != 0 && rt->rt_rmx.rmx_ssthresh != 0)
735 || dosavessthresh) {
736 /*
737 * convert the limit from user data bytes to
738 * packets then to packet data bytes.
739 */
740 i = (i + tp->t_maxseg / 2) / tp->t_maxseg;
741 if (i < 2)
742 i = 2;
743 i *= (u_long)(tp->t_maxseg +
744#ifdef INET6
745 (isipv6 ? sizeof (struct ip6_hdr) +
746 sizeof (struct tcphdr) :
747#endif
748 sizeof (struct tcpiphdr)
749#ifdef INET6
750 )
751#endif
752 );
753 if (rt->rt_rmx.rmx_ssthresh)
754 rt->rt_rmx.rmx_ssthresh =
755 (rt->rt_rmx.rmx_ssthresh + i) / 2;
756 else
757 rt->rt_rmx.rmx_ssthresh = i;
758 tcpstat.tcps_cachedssthresh++;
759 }
760 }
761 no_valid_rt:
762 /* free the reassembly queue, if any */
763 while ((q = LIST_FIRST(&tp->t_segq)) != NULL) {
764 LIST_REMOVE(q, tqe_q);
765 m_freem(q->tqe_m);
766 FREE(q, M_TSEGQ);
767 }
768 inp->inp_ppcb = NULL;
769 tp->t_inpcb = NULL;
770 uma_zfree(tcpcb_zone, tp);
771 soisdisconnected(so);
772}
773
774/*
775 * Close a TCP control block:
776 * discard all space held by the tcp
777 * discard internet protocol block
778 * wake up any sleepers
779 */
780struct tcpcb *
781tcp_close(tp)
782 struct tcpcb *tp;
783{
784 struct inpcb *inp = tp->t_inpcb;
785#ifdef INET6
786 struct socket *so = inp->inp_socket;
787#endif
788
789 tcp_discardcb(tp);
790#ifdef INET6
791 if (INP_CHECK_SOCKAF(so, AF_INET6))
792 in6_pcbdetach(inp);
793 else
794#endif
795 in_pcbdetach(inp);
796 tcpstat.tcps_closed++;
797 return ((struct tcpcb *)0);
798}
799
800void
801tcp_drain()
802{
803 if (do_tcpdrain)
804 {
805 struct inpcb *inpb;
806 struct tcpcb *tcpb;
807 struct tseg_qent *te;
808
809 /*
810 * Walk the tcpbs, if existing, and flush the reassembly queue,
811 * if there is one...
812 * XXX: The "Net/3" implementation doesn't imply that the TCP
813 * reassembly queue should be flushed, but in a situation
814 * where we're really low on mbufs, this is potentially
815 * usefull.
816 */
817 INP_INFO_RLOCK(&tcbinfo);
818 LIST_FOREACH(inpb, tcbinfo.listhead, inp_list) {
819 if (inpb->inp_vflag & INP_TIMEWAIT)
820 continue;
821 INP_LOCK(inpb);
822 if ((tcpb = intotcpcb(inpb))) {
823 while ((te = LIST_FIRST(&tcpb->t_segq))
824 != NULL) {
825 LIST_REMOVE(te, tqe_q);
826 m_freem(te->tqe_m);
827 FREE(te, M_TSEGQ);
828 }
829 }
830 INP_UNLOCK(inpb);
831 }
832 INP_INFO_RUNLOCK(&tcbinfo);
833 }
834}
835
836/*
837 * Notify a tcp user of an asynchronous error;
838 * store error as soft error, but wake up user
839 * (for now, won't do anything until can select for soft error).
840 *
841 * Do not wake up user since there currently is no mechanism for
842 * reporting soft errors (yet - a kqueue filter may be added).
843 */
844static struct inpcb *
845tcp_notify(inp, error)
846 struct inpcb *inp;
847 int error;
848{
849 struct tcpcb *tp = (struct tcpcb *)inp->inp_ppcb;
850
851 /*
852 * Ignore some errors if we are hooked up.
853 * If connection hasn't completed, has retransmitted several times,
854 * and receives a second error, give up now. This is better
855 * than waiting a long time to establish a connection that
856 * can never complete.
857 */
858 if (tp->t_state == TCPS_ESTABLISHED &&
859 (error == EHOSTUNREACH || error == ENETUNREACH ||
860 error == EHOSTDOWN)) {
861 return inp;
862 } else if (tp->t_state < TCPS_ESTABLISHED && tp->t_rxtshift > 3 &&
863 tp->t_softerror) {
864 tcp_drop(tp, error);
865 return (struct inpcb *)0;
866 } else {
867 tp->t_softerror = error;
868 return inp;
869 }
870#if 0
871 wakeup( &so->so_timeo);
872 sorwakeup(so);
873 sowwakeup(so);
874#endif
875}
876
877static int
878tcp_pcblist(SYSCTL_HANDLER_ARGS)
879{
880 int error, i, n, s;
881 struct inpcb *inp, **inp_list;
882 inp_gen_t gencnt;
883 struct xinpgen xig;
884
885 /*
886 * The process of preparing the TCB list is too time-consuming and
887 * resource-intensive to repeat twice on every request.
888 */
889 if (req->oldptr == 0) {
890 n = tcbinfo.ipi_count;
891 req->oldidx = 2 * (sizeof xig)
892 + (n + n/8) * sizeof(struct xtcpcb);
893 return 0;
894 }
895
896 if (req->newptr != 0)
897 return EPERM;
898
899 /*
900 * OK, now we're committed to doing something.
901 */
902 s = splnet();
903 INP_INFO_RLOCK(&tcbinfo);
904 gencnt = tcbinfo.ipi_gencnt;
905 n = tcbinfo.ipi_count;
906 INP_INFO_RUNLOCK(&tcbinfo);
907 splx(s);
908
909 sysctl_wire_old_buffer(req, 2 * (sizeof xig)
910 + n * sizeof(struct xtcpcb));
911
912 xig.xig_len = sizeof xig;
913 xig.xig_count = n;
914 xig.xig_gen = gencnt;
915 xig.xig_sogen = so_gencnt;
916 error = SYSCTL_OUT(req, &xig, sizeof xig);
917 if (error)
918 return error;
919
920 inp_list = malloc(n * sizeof *inp_list, M_TEMP, M_WAITOK);
921 if (inp_list == 0)
922 return ENOMEM;
923
924 s = splnet();
925 INP_INFO_RLOCK(&tcbinfo);
926 for (inp = LIST_FIRST(tcbinfo.listhead), i = 0; inp && i < n;
927 inp = LIST_NEXT(inp, inp_list)) {
928 INP_LOCK(inp);
929 if (inp->inp_gencnt <= gencnt) {
930 /*
931 * XXX: This use of cr_cansee(), introduced with
932 * TCP state changes, is not quite right, but for
933 * now, better than nothing.
934 */
935 if (inp->inp_vflag & INP_TIMEWAIT)
936 error = cr_cansee(req->td->td_ucred,
937 intotw(inp)->tw_cred);
938 else
939 error = cr_canseesocket(req->td->td_ucred,
940 inp->inp_socket);
941 if (error == 0)
942 inp_list[i++] = inp;
943 }
944 INP_UNLOCK(inp);
945 }
946 INP_INFO_RUNLOCK(&tcbinfo);
947 splx(s);
948 n = i;
949
950 error = 0;
951 for (i = 0; i < n; i++) {
952 inp = inp_list[i];
953 if (inp->inp_gencnt <= gencnt) {
954 struct xtcpcb xt;
955 caddr_t inp_ppcb;
956 xt.xt_len = sizeof xt;
957 /* XXX should avoid extra copy */
958 bcopy(inp, &xt.xt_inp, sizeof *inp);
959 inp_ppcb = inp->inp_ppcb;
960 if (inp_ppcb == NULL)
961 bzero((char *) &xt.xt_tp, sizeof xt.xt_tp);
962 else if (inp->inp_vflag & INP_TIMEWAIT) {
963 bzero((char *) &xt.xt_tp, sizeof xt.xt_tp);
964 xt.xt_tp.t_state = TCPS_TIME_WAIT;
965 } else
966 bcopy(inp_ppcb, &xt.xt_tp, sizeof xt.xt_tp);
967 if (inp->inp_socket)
968 sotoxsocket(inp->inp_socket, &xt.xt_socket);
969 else {
970 bzero(&xt.xt_socket, sizeof xt.xt_socket);
971 xt.xt_socket.xso_protocol = IPPROTO_TCP;
972 }
973 xt.xt_inp.inp_gencnt = inp->inp_gencnt;
974 error = SYSCTL_OUT(req, &xt, sizeof xt);
975 }
976 }
977 if (!error) {
978 /*
979 * Give the user an updated idea of our state.
980 * If the generation differs from what we told
981 * her before, she knows that something happened
982 * while we were processing this request, and it
983 * might be necessary to retry.
984 */
985 s = splnet();
986 INP_INFO_RLOCK(&tcbinfo);
987 xig.xig_gen = tcbinfo.ipi_gencnt;
988 xig.xig_sogen = so_gencnt;
989 xig.xig_count = tcbinfo.ipi_count;
990 INP_INFO_RUNLOCK(&tcbinfo);
991 splx(s);
992 error = SYSCTL_OUT(req, &xig, sizeof xig);
993 }
994 free(inp_list, M_TEMP);
995 return error;
996}
997
998SYSCTL_PROC(_net_inet_tcp, TCPCTL_PCBLIST, pcblist, CTLFLAG_RD, 0, 0,
999 tcp_pcblist, "S,xtcpcb", "List of active TCP connections");
1000
1001static int
1002tcp_getcred(SYSCTL_HANDLER_ARGS)
1003{
1004 struct xucred xuc;
1005 struct sockaddr_in addrs[2];
1006 struct inpcb *inp;
1007 int error, s;
1008
1009 error = suser_cred(req->td->td_ucred, PRISON_ROOT);
1010 if (error)
1011 return (error);
1012 error = SYSCTL_IN(req, addrs, sizeof(addrs));
1013 if (error)
1014 return (error);
1015 s = splnet();
1016 INP_INFO_RLOCK(&tcbinfo);
1017 inp = in_pcblookup_hash(&tcbinfo, addrs[1].sin_addr, addrs[1].sin_port,
1018 addrs[0].sin_addr, addrs[0].sin_port, 0, NULL);
1019 if (inp == NULL) {
1020 error = ENOENT;
1021 goto outunlocked;
1022 }
1023 INP_LOCK(inp);
1024 if (inp->inp_socket == NULL) {
1025 error = ENOENT;
1026 goto out;
1027 }
1028 error = cr_canseesocket(req->td->td_ucred, inp->inp_socket);
1029 if (error)
1030 goto out;
1031 cru2x(inp->inp_socket->so_cred, &xuc);
1032out:
1033 INP_UNLOCK(inp);
1034outunlocked:
1035 INP_INFO_RUNLOCK(&tcbinfo);
1036 splx(s);
1037 if (error == 0)
1038 error = SYSCTL_OUT(req, &xuc, sizeof(struct xucred));
1039 return (error);
1040}
1041
1042SYSCTL_PROC(_net_inet_tcp, OID_AUTO, getcred,
1043 CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_PRISON, 0, 0,
1044 tcp_getcred, "S,xucred", "Get the xucred of a TCP connection");
1045
1046#ifdef INET6
1047static int
1048tcp6_getcred(SYSCTL_HANDLER_ARGS)
1049{
1050 struct xucred xuc;
1051 struct sockaddr_in6 addrs[2];
1052 struct inpcb *inp;
1053 int error, s, mapped = 0;
1054
1055 error = suser_cred(req->td->td_ucred, PRISON_ROOT);
1056 if (error)
1057 return (error);
1058 error = SYSCTL_IN(req, addrs, sizeof(addrs));
1059 if (error)
1060 return (error);
1061 if (IN6_IS_ADDR_V4MAPPED(&addrs[0].sin6_addr)) {
1062 if (IN6_IS_ADDR_V4MAPPED(&addrs[1].sin6_addr))
1063 mapped = 1;
1064 else
1065 return (EINVAL);
1066 }
1067 s = splnet();
1068 INP_INFO_RLOCK(&tcbinfo);
1069 if (mapped == 1)
1070 inp = in_pcblookup_hash(&tcbinfo,
1071 *(struct in_addr *)&addrs[1].sin6_addr.s6_addr[12],
1072 addrs[1].sin6_port,
1073 *(struct in_addr *)&addrs[0].sin6_addr.s6_addr[12],
1074 addrs[0].sin6_port,
1075 0, NULL);
1076 else
1077 inp = in6_pcblookup_hash(&tcbinfo, &addrs[1].sin6_addr,
1078 addrs[1].sin6_port,
1079 &addrs[0].sin6_addr, addrs[0].sin6_port,
1080 0, NULL);
1081 if (inp == NULL) {
1082 error = ENOENT;
1083 goto outunlocked;
1084 }
1085 INP_LOCK(inp);
1086 if (inp->inp_socket == NULL) {
1087 error = ENOENT;
1088 goto out;
1089 }
1090 error = cr_canseesocket(req->td->td_ucred, inp->inp_socket);
1091 if (error)
1092 goto out;
1093 cru2x(inp->inp_socket->so_cred, &xuc);
1094out:
1095 INP_UNLOCK(inp);
1096outunlocked:
1097 INP_INFO_RUNLOCK(&tcbinfo);
1098 splx(s);
1099 if (error == 0)
1100 error = SYSCTL_OUT(req, &xuc, sizeof(struct xucred));
1101 return (error);
1102}
1103
1104SYSCTL_PROC(_net_inet6_tcp6, OID_AUTO, getcred,
1105 CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_PRISON, 0, 0,
1106 tcp6_getcred, "S,xucred", "Get the xucred of a TCP6 connection");
1107#endif
1108
1109
1110void
1111tcp_ctlinput(cmd, sa, vip)
1112 int cmd;
1113 struct sockaddr *sa;
1114 void *vip;
1115{
1116 struct ip *ip = vip;
1117 struct tcphdr *th;
1118 struct in_addr faddr;
1119 struct inpcb *inp;
1120 struct tcpcb *tp;
1121 struct inpcb *(*notify)(struct inpcb *, int) = tcp_notify;
1122 tcp_seq icmp_seq;
1123 int s;
1124
1125 faddr = ((struct sockaddr_in *)sa)->sin_addr;
1126 if (sa->sa_family != AF_INET || faddr.s_addr == INADDR_ANY)
1127 return;
1128
1129 if (cmd == PRC_QUENCH)
1130 notify = tcp_quench;
1131 else if (icmp_may_rst && (cmd == PRC_UNREACH_ADMIN_PROHIB ||
1132 cmd == PRC_UNREACH_PORT || cmd == PRC_TIMXCEED_INTRANS) && ip)
1133 notify = tcp_drop_syn_sent;
1134 else if (cmd == PRC_MSGSIZE)
1135 notify = tcp_mtudisc;
1136 else if (PRC_IS_REDIRECT(cmd)) {
1137 ip = 0;
1138 notify = in_rtchange;
1139 } else if (cmd == PRC_HOSTDEAD)
1140 ip = 0;
|
1208 return;
1209
1210 /* if the parameter is from icmp6, decode it. */
1211 if (d != NULL) {
1212 ip6cp = (struct ip6ctlparam *)d;
1213 m = ip6cp->ip6c_m;
1214 ip6 = ip6cp->ip6c_ip6;
1215 off = ip6cp->ip6c_off;
1216 sa6_src = ip6cp->ip6c_src;
1217 } else {
1218 m = NULL;
1219 ip6 = NULL;
1220 off = 0; /* fool gcc */
1221 sa6_src = &sa6_any;
1222 }
1223
1224 if (ip6) {
1225 struct in_conninfo inc;
1226 /*
1227 * XXX: We assume that when IPV6 is non NULL,
1228 * M and OFF are valid.
1229 */
1230
1231 /* check if we can safely examine src and dst ports */
1232 if (m->m_pkthdr.len < off + sizeof(*thp))
1233 return;
1234
1235 bzero(&th, sizeof(th));
1236 m_copydata(m, off, sizeof(*thp), (caddr_t)&th);
1237
1238 in6_pcbnotify(&tcb, sa, th.th_dport,
1239 (struct sockaddr *)ip6cp->ip6c_src,
1240 th.th_sport, cmd, notify);
1241
1242 inc.inc_fport = th.th_dport;
1243 inc.inc_lport = th.th_sport;
1244 inc.inc6_faddr = ((struct sockaddr_in6 *)sa)->sin6_addr;
1245 inc.inc6_laddr = ip6cp->ip6c_src->sin6_addr;
1246 inc.inc_isipv6 = 1;
1247 syncache_unreach(&inc, &th);
1248 } else
1249 in6_pcbnotify(&tcb, sa, 0, (const struct sockaddr *)sa6_src,
1250 0, cmd, notify);
1251}
1252#endif /* INET6 */
1253
1254
1255/*
1256 * Following is where TCP initial sequence number generation occurs.
1257 *
1258 * There are two places where we must use initial sequence numbers:
1259 * 1. In SYN-ACK packets.
1260 * 2. In SYN packets.
1261 *
1262 * All ISNs for SYN-ACK packets are generated by the syncache. See
1263 * tcp_syncache.c for details.
1264 *
1265 * The ISNs in SYN packets must be monotonic; TIME_WAIT recycling
1266 * depends on this property. In addition, these ISNs should be
1267 * unguessable so as to prevent connection hijacking. To satisfy
1268 * the requirements of this situation, the algorithm outlined in
1269 * RFC 1948 is used to generate sequence numbers.
1270 *
1271 * Implementation details:
1272 *
1273 * Time is based off the system timer, and is corrected so that it
1274 * increases by one megabyte per second. This allows for proper
1275 * recycling on high speed LANs while still leaving over an hour
1276 * before rollover.
1277 *
1278 * net.inet.tcp.isn_reseed_interval controls the number of seconds
1279 * between seeding of isn_secret. This is normally set to zero,
1280 * as reseeding should not be necessary.
1281 *
1282 */
1283
1284#define ISN_BYTES_PER_SECOND 1048576
1285
1286u_char isn_secret[32];
1287int isn_last_reseed;
1288MD5_CTX isn_ctx;
1289
1290tcp_seq
1291tcp_new_isn(tp)
1292 struct tcpcb *tp;
1293{
1294 u_int32_t md5_buffer[4];
1295 tcp_seq new_isn;
1296
1297 /* Seed if this is the first use, reseed if requested. */
1298 if ((isn_last_reseed == 0) || ((tcp_isn_reseed_interval > 0) &&
1299 (((u_int)isn_last_reseed + (u_int)tcp_isn_reseed_interval*hz)
1300 < (u_int)ticks))) {
1301 read_random(&isn_secret, sizeof(isn_secret));
1302 isn_last_reseed = ticks;
1303 }
1304
1305 /* Compute the md5 hash and return the ISN. */
1306 MD5Init(&isn_ctx);
1307 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_fport, sizeof(u_short));
1308 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_lport, sizeof(u_short));
1309#ifdef INET6
1310 if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0) {
1311 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_faddr,
1312 sizeof(struct in6_addr));
1313 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_laddr,
1314 sizeof(struct in6_addr));
1315 } else
1316#endif
1317 {
1318 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_faddr,
1319 sizeof(struct in_addr));
1320 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_laddr,
1321 sizeof(struct in_addr));
1322 }
1323 MD5Update(&isn_ctx, (u_char *) &isn_secret, sizeof(isn_secret));
1324 MD5Final((u_char *) &md5_buffer, &isn_ctx);
1325 new_isn = (tcp_seq) md5_buffer[0];
1326 new_isn += ticks * (ISN_BYTES_PER_SECOND / hz);
1327 return new_isn;
1328}
1329
1330/*
1331 * When a source quench is received, close congestion window
1332 * to one segment. We will gradually open it again as we proceed.
1333 */
1334struct inpcb *
1335tcp_quench(inp, errno)
1336 struct inpcb *inp;
1337 int errno;
1338{
1339 struct tcpcb *tp = intotcpcb(inp);
1340
1341 if (tp)
1342 tp->snd_cwnd = tp->t_maxseg;
1343 return (inp);
1344}
1345
1346/*
1347 * When a specific ICMP unreachable message is received and the
1348 * connection state is SYN-SENT, drop the connection. This behavior
1349 * is controlled by the icmp_may_rst sysctl.
1350 */
1351struct inpcb *
1352tcp_drop_syn_sent(inp, errno)
1353 struct inpcb *inp;
1354 int errno;
1355{
1356 struct tcpcb *tp = intotcpcb(inp);
1357
1358 if (tp && tp->t_state == TCPS_SYN_SENT) {
1359 tcp_drop(tp, errno);
1360 return (struct inpcb *)0;
1361 }
1362 return inp;
1363}
1364
1365/*
1366 * When `need fragmentation' ICMP is received, update our idea of the MSS
1367 * based on the new value in the route. Also nudge TCP to send something,
1368 * since we know the packet we just sent was dropped.
1369 * This duplicates some code in the tcp_mss() function in tcp_input.c.
1370 */
1371struct inpcb *
1372tcp_mtudisc(inp, errno)
1373 struct inpcb *inp;
1374 int errno;
1375{
1376 struct tcpcb *tp = intotcpcb(inp);
1377 struct rtentry *rt;
1378 struct rmxp_tao *taop;
1379 struct socket *so = inp->inp_socket;
1380 int offered;
1381 int mss;
1382#ifdef INET6
1383 int isipv6 = (tp->t_inpcb->inp_vflag & INP_IPV6) != 0;
1384#endif /* INET6 */
1385
1386 if (tp) {
1387#ifdef INET6
1388 if (isipv6)
1389 rt = tcp_rtlookup6(&inp->inp_inc);
1390 else
1391#endif /* INET6 */
1392 rt = tcp_rtlookup(&inp->inp_inc);
1393 if (!rt || !rt->rt_rmx.rmx_mtu) {
1394 tp->t_maxopd = tp->t_maxseg =
1395#ifdef INET6
1396 isipv6 ? tcp_v6mssdflt :
1397#endif /* INET6 */
1398 tcp_mssdflt;
1399 return inp;
1400 }
1401 taop = rmx_taop(rt->rt_rmx);
1402 offered = taop->tao_mssopt;
1403 mss = rt->rt_rmx.rmx_mtu -
1404#ifdef INET6
1405 (isipv6 ?
1406 sizeof(struct ip6_hdr) + sizeof(struct tcphdr) :
1407#endif /* INET6 */
1408 sizeof(struct tcpiphdr)
1409#ifdef INET6
1410 )
1411#endif /* INET6 */
1412 ;
1413
1414 if (offered)
1415 mss = min(mss, offered);
1416 /*
1417 * XXX - The above conditional probably violates the TCP
1418 * spec. The problem is that, since we don't know the
1419 * other end's MSS, we are supposed to use a conservative
1420 * default. But, if we do that, then MTU discovery will
1421 * never actually take place, because the conservative
1422 * default is much less than the MTUs typically seen
1423 * on the Internet today. For the moment, we'll sweep
1424 * this under the carpet.
1425 *
1426 * The conservative default might not actually be a problem
1427 * if the only case this occurs is when sending an initial
1428 * SYN with options and data to a host we've never talked
1429 * to before. Then, they will reply with an MSS value which
1430 * will get recorded and the new parameters should get
1431 * recomputed. For Further Study.
1432 */
1433 if (tp->t_maxopd <= mss)
1434 return inp;
1435 tp->t_maxopd = mss;
1436
1437 if ((tp->t_flags & (TF_REQ_TSTMP|TF_NOOPT)) == TF_REQ_TSTMP &&
1438 (tp->t_flags & TF_RCVD_TSTMP) == TF_RCVD_TSTMP)
1439 mss -= TCPOLEN_TSTAMP_APPA;
1440 if ((tp->t_flags & (TF_REQ_CC|TF_NOOPT)) == TF_REQ_CC &&
1441 (tp->t_flags & TF_RCVD_CC) == TF_RCVD_CC)
1442 mss -= TCPOLEN_CC_APPA;
1443#if (MCLBYTES & (MCLBYTES - 1)) == 0
1444 if (mss > MCLBYTES)
1445 mss &= ~(MCLBYTES-1);
1446#else
1447 if (mss > MCLBYTES)
1448 mss = mss / MCLBYTES * MCLBYTES;
1449#endif
1450 if (so->so_snd.sb_hiwat < mss)
1451 mss = so->so_snd.sb_hiwat;
1452
1453 tp->t_maxseg = mss;
1454
1455 tcpstat.tcps_mturesent++;
1456 tp->t_rtttime = 0;
1457 tp->snd_nxt = tp->snd_una;
1458 tcp_output(tp);
1459 }
1460 return inp;
1461}
1462
1463/*
1464 * Look-up the routing entry to the peer of this inpcb. If no route
1465 * is found and it cannot be allocated, then return NULL. This routine
1466 * is called by TCP routines that access the rmx structure and by tcp_mss
1467 * to get the interface MTU.
1468 */
1469struct rtentry *
1470tcp_rtlookup(inc)
1471 struct in_conninfo *inc;
1472{
1473 struct route *ro;
1474 struct rtentry *rt;
1475
1476 ro = &inc->inc_route;
1477 rt = ro->ro_rt;
1478 if (rt == NULL || !(rt->rt_flags & RTF_UP)) {
1479 /* No route yet, so try to acquire one */
1480 if (inc->inc_faddr.s_addr != INADDR_ANY) {
1481 ro->ro_dst.sa_family = AF_INET;
1482 ro->ro_dst.sa_len = sizeof(struct sockaddr_in);
1483 ((struct sockaddr_in *) &ro->ro_dst)->sin_addr =
1484 inc->inc_faddr;
1485 rtalloc(ro);
1486 rt = ro->ro_rt;
1487 }
1488 }
1489 return rt;
1490}
1491
1492#ifdef INET6
1493struct rtentry *
1494tcp_rtlookup6(inc)
1495 struct in_conninfo *inc;
1496{
1497 struct route_in6 *ro6;
1498 struct rtentry *rt;
1499
1500 ro6 = &inc->inc6_route;
1501 rt = ro6->ro_rt;
1502 if (rt == NULL || !(rt->rt_flags & RTF_UP)) {
1503 /* No route yet, so try to acquire one */
1504 if (!IN6_IS_ADDR_UNSPECIFIED(&inc->inc6_faddr)) {
1505 ro6->ro_dst.sin6_family = AF_INET6;
1506 ro6->ro_dst.sin6_len = sizeof(struct sockaddr_in6);
1507 ro6->ro_dst.sin6_addr = inc->inc6_faddr;
1508 rtalloc((struct route *)ro6);
1509 rt = ro6->ro_rt;
1510 }
1511 }
1512 return rt;
1513}
1514#endif /* INET6 */
1515
1516#ifdef IPSEC
1517/* compute ESP/AH header size for TCP, including outer IP header. */
1518size_t
1519ipsec_hdrsiz_tcp(tp)
1520 struct tcpcb *tp;
1521{
1522 struct inpcb *inp;
1523 struct mbuf *m;
1524 size_t hdrsiz;
1525 struct ip *ip;
1526#ifdef INET6
1527 struct ip6_hdr *ip6;
1528#endif
1529 struct tcphdr *th;
1530
1531 if ((tp == NULL) || ((inp = tp->t_inpcb) == NULL))
1532 return 0;
1533 MGETHDR(m, M_DONTWAIT, MT_DATA);
1534 if (!m)
1535 return 0;
1536
1537#ifdef INET6
1538 if ((inp->inp_vflag & INP_IPV6) != 0) {
1539 ip6 = mtod(m, struct ip6_hdr *);
1540 th = (struct tcphdr *)(ip6 + 1);
1541 m->m_pkthdr.len = m->m_len =
1542 sizeof(struct ip6_hdr) + sizeof(struct tcphdr);
1543 tcpip_fillheaders(inp, ip6, th);
1544 hdrsiz = ipsec6_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp);
1545 } else
1546#endif /* INET6 */
1547 {
1548 ip = mtod(m, struct ip *);
1549 th = (struct tcphdr *)(ip + 1);
1550 m->m_pkthdr.len = m->m_len = sizeof(struct tcpiphdr);
1551 tcpip_fillheaders(inp, ip, th);
1552 hdrsiz = ipsec4_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp);
1553 }
1554
1555 m_free(m);
1556 return hdrsiz;
1557}
1558#endif /*IPSEC*/
1559
1560/*
1561 * Return a pointer to the cached information about the remote host.
1562 * The cached information is stored in the protocol specific part of
1563 * the route metrics.
1564 */
1565struct rmxp_tao *
1566tcp_gettaocache(inc)
1567 struct in_conninfo *inc;
1568{
1569 struct rtentry *rt;
1570
1571#ifdef INET6
1572 if (inc->inc_isipv6)
1573 rt = tcp_rtlookup6(inc);
1574 else
1575#endif /* INET6 */
1576 rt = tcp_rtlookup(inc);
1577
1578 /* Make sure this is a host route and is up. */
1579 if (rt == NULL ||
1580 (rt->rt_flags & (RTF_UP|RTF_HOST)) != (RTF_UP|RTF_HOST))
1581 return NULL;
1582
1583 return rmx_taop(rt->rt_rmx);
1584}
1585
1586/*
1587 * Clear all the TAO cache entries, called from tcp_init.
1588 *
1589 * XXX
1590 * This routine is just an empty one, because we assume that the routing
1591 * routing tables are initialized at the same time when TCP, so there is
1592 * nothing in the cache left over.
1593 */
1594static void
1595tcp_cleartaocache()
1596{
1597}
1598
1599/*
1600 * Move a TCP connection into TIME_WAIT state.
1601 * tcbinfo is unlocked.
1602 * inp is locked, and is unlocked before returning.
1603 */
1604void
1605tcp_twstart(tp)
1606 struct tcpcb *tp;
1607{
1608 struct tcptw *tw;
1609 struct inpcb *inp;
1610 int tw_time, acknow;
1611 struct socket *so;
1612
1613 tw = uma_zalloc(tcptw_zone, M_NOWAIT);
1614 if (tw == NULL) {
1615 tw = tcp_timer_2msl_tw(1);
1616 if (tw == NULL) {
1617 tcp_close(tp);
1618 return;
1619 }
1620 }
1621 inp = tp->t_inpcb;
1622 tw->tw_inpcb = inp;
1623
1624 /*
1625 * Recover last window size sent.
1626 */
1627 tw->last_win = (tp->rcv_adv - tp->rcv_nxt) >> tp->rcv_scale;
1628
1629 /*
1630 * Set t_recent if timestamps are used on the connection.
1631 */
1632 if ((tp->t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP|TF_NOOPT)) ==
1633 (TF_REQ_TSTMP|TF_RCVD_TSTMP))
1634 tw->t_recent = tp->ts_recent;
1635 else
1636 tw->t_recent = 0;
1637
1638 tw->snd_nxt = tp->snd_nxt;
1639 tw->rcv_nxt = tp->rcv_nxt;
1640 tw->cc_recv = tp->cc_recv;
1641 tw->cc_send = tp->cc_send;
1642 tw->t_starttime = tp->t_starttime;
1643 tw->tw_time = 0;
1644
1645/* XXX
1646 * If this code will
1647 * be used for fin-wait-2 state also, then we may need
1648 * a ts_recent from the last segment.
1649 */
1650 /* Shorten TIME_WAIT [RFC-1644, p.28] */
1651 if (tp->cc_recv != 0 && (ticks - tp->t_starttime) < tcp_msl) {
1652 tw_time = tp->t_rxtcur * TCPTV_TWTRUNC;
1653 /* For T/TCP client, force ACK now. */
1654 acknow = 1;
1655 } else {
1656 tw_time = 2 * tcp_msl;
1657 acknow = tp->t_flags & TF_ACKNOW;
1658 }
1659 tcp_discardcb(tp);
1660 so = inp->inp_socket;
1661 so->so_pcb = NULL;
1662 tw->tw_cred = crhold(so->so_cred);
1663 tw->tw_so_options = so->so_options;
1664 if (acknow)
1665 tcp_twrespond(tw, so, NULL, TH_ACK);
1666 sotryfree(so);
1667 inp->inp_socket = NULL;
1668 inp->inp_ppcb = (caddr_t)tw;
1669 inp->inp_vflag |= INP_TIMEWAIT;
1670 tcp_timer_2msl_reset(tw, tw_time);
1671 INP_UNLOCK(inp);
1672}
1673
1674struct tcptw *
1675tcp_twclose(struct tcptw *tw, int reuse)
1676{
1677 struct inpcb *inp;
1678
1679 inp = tw->tw_inpcb;
1680 tw->tw_inpcb = NULL;
1681 tcp_timer_2msl_stop(tw);
1682 inp->inp_ppcb = NULL;
1683#ifdef INET6
1684 if (inp->inp_vflag & INP_IPV6PROTO)
1685 in6_pcbdetach(inp);
1686 else
1687#endif
1688 in_pcbdetach(inp);
1689 tcpstat.tcps_closed++;
1690 if (reuse)
1691 return (tw);
1692 uma_zfree(tcptw_zone, tw);
1693 return (NULL);
1694}
1695
1696/*
1697 * One of so and msrc must be non-NULL for use by the MAC Framework to
1698 * construct a label for ay resulting packet.
1699 */
1700int
1701tcp_twrespond(struct tcptw *tw, struct socket *so, struct mbuf *msrc,
1702 int flags)
1703{
1704 struct inpcb *inp = tw->tw_inpcb;
1705 struct tcphdr *th;
1706 struct mbuf *m;
1707 struct ip *ip = NULL;
1708 u_int8_t *optp;
1709 u_int hdrlen, optlen;
1710 int error;
1711#ifdef INET6
1712 struct ip6_hdr *ip6 = NULL;
1713 int isipv6 = inp->inp_inc.inc_isipv6;
1714#endif
1715
1716 KASSERT(so != NULL || msrc != NULL,
1717 ("tcp_twrespond: so and msrc NULL"));
1718
1719 m = m_gethdr(M_DONTWAIT, MT_HEADER);
1720 if (m == NULL)
1721 return (ENOBUFS);
1722 m->m_data += max_linkhdr;
1723
1724#ifdef MAC
1725 if (so != NULL)
1726 mac_create_mbuf_from_socket(so, m);
1727 else
1728 mac_create_mbuf_netlayer(msrc, m);
1729#endif
1730
1731#ifdef INET6
1732 if (isipv6) {
1733 hdrlen = sizeof(struct ip6_hdr) + sizeof(struct tcphdr);
1734 ip6 = mtod(m, struct ip6_hdr *);
1735 th = (struct tcphdr *)(ip6 + 1);
1736 tcpip_fillheaders(inp, ip6, th);
1737 } else
1738#endif
1739 {
1740 hdrlen = sizeof(struct tcpiphdr);
1741 ip = mtod(m, struct ip *);
1742 th = (struct tcphdr *)(ip + 1);
1743 tcpip_fillheaders(inp, ip, th);
1744 }
1745 optp = (u_int8_t *)(th + 1);
1746
1747 /*
1748 * Send a timestamp and echo-reply if both our side and our peer
1749 * have sent timestamps in our SYN's and this is not a RST.
1750 */
1751 if (tw->t_recent && flags == TH_ACK) {
1752 u_int32_t *lp = (u_int32_t *)optp;
1753
1754 /* Form timestamp option as shown in appendix A of RFC 1323. */
1755 *lp++ = htonl(TCPOPT_TSTAMP_HDR);
1756 *lp++ = htonl(ticks);
1757 *lp = htonl(tw->t_recent);
1758 optp += TCPOLEN_TSTAMP_APPA;
1759 }
1760
1761 /*
1762 * Send `CC-family' options if needed, and it's not a RST.
1763 */
1764 if (tw->cc_recv != 0 && flags == TH_ACK) {
1765 u_int32_t *lp = (u_int32_t *)optp;
1766
1767 *lp++ = htonl(TCPOPT_CC_HDR(TCPOPT_CC));
1768 *lp = htonl(tw->cc_send);
1769 optp += TCPOLEN_CC_APPA;
1770 }
1771 optlen = optp - (u_int8_t *)(th + 1);
1772
1773 m->m_len = hdrlen + optlen;
1774 m->m_pkthdr.len = m->m_len;
1775
1776 KASSERT(max_linkhdr + m->m_len <= MHLEN, ("tcptw: mbuf too small"));
1777
1778 th->th_seq = htonl(tw->snd_nxt);
1779 th->th_ack = htonl(tw->rcv_nxt);
1780 th->th_off = (sizeof(struct tcphdr) + optlen) >> 2;
1781 th->th_flags = flags;
1782 th->th_win = htons(tw->last_win);
1783
1784#ifdef INET6
1785 if (isipv6) {
1786 th->th_sum = in6_cksum(m, IPPROTO_TCP, sizeof(struct ip6_hdr),
1787 sizeof(struct tcphdr) + optlen);
1788 ip6->ip6_hlim = in6_selecthlim(inp, inp->in6p_route.ro_rt ?
1789 inp->in6p_route.ro_rt->rt_ifp : NULL);
1790 error = ip6_output(m, inp->in6p_outputopts, &inp->in6p_route,
1791 (tw->tw_so_options & SO_DONTROUTE), NULL, NULL, inp);
1792 } else
1793#endif
1794 {
1795 th->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr,
1796 htons(sizeof(struct tcphdr) + optlen + IPPROTO_TCP));
1797 m->m_pkthdr.csum_flags = CSUM_TCP;
1798 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum);
1799 ip->ip_len = m->m_pkthdr.len;
1800 error = ip_output(m, inp->inp_options, &inp->inp_route,
1801 (tw->tw_so_options & SO_DONTROUTE), NULL, inp);
1802 }
1803 if (flags & TH_ACK)
1804 tcpstat.tcps_sndacks++;
1805 else
1806 tcpstat.tcps_sndctrl++;
1807 tcpstat.tcps_sndtotal++;
1808 return (error);
1809}
1810
1811/*
1812 * TCP BANDWIDTH DELAY PRODUCT WINDOW LIMITING
1813 *
1814 * This code attempts to calculate the bandwidth-delay product as a
1815 * means of determining the optimal window size to maximize bandwidth,
1816 * minimize RTT, and avoid the over-allocation of buffers on interfaces and
1817 * routers. This code also does a fairly good job keeping RTTs in check
1818 * across slow links like modems. We implement an algorithm which is very
1819 * similar (but not meant to be) TCP/Vegas. The code operates on the
1820 * transmitter side of a TCP connection and so only effects the transmit
1821 * side of the connection.
1822 *
1823 * BACKGROUND: TCP makes no provision for the management of buffer space
1824 * at the end points or at the intermediate routers and switches. A TCP
1825 * stream, whether using NewReno or not, will eventually buffer as
1826 * many packets as it is able and the only reason this typically works is
1827 * due to the fairly small default buffers made available for a connection
1828 * (typicaly 16K or 32K). As machines use larger windows and/or window
1829 * scaling it is now fairly easy for even a single TCP connection to blow-out
1830 * all available buffer space not only on the local interface, but on
1831 * intermediate routers and switches as well. NewReno makes a misguided
1832 * attempt to 'solve' this problem by waiting for an actual failure to occur,
1833 * then backing off, then steadily increasing the window again until another
1834 * failure occurs, ad-infinitum. This results in terrible oscillation that
1835 * is only made worse as network loads increase and the idea of intentionally
1836 * blowing out network buffers is, frankly, a terrible way to manage network
1837 * resources.
1838 *
1839 * It is far better to limit the transmit window prior to the failure
1840 * condition being achieved. There are two general ways to do this: First
1841 * you can 'scan' through different transmit window sizes and locate the
1842 * point where the RTT stops increasing, indicating that you have filled the
1843 * pipe, then scan backwards until you note that RTT stops decreasing, then
1844 * repeat ad-infinitum. This method works in principle but has severe
1845 * implementation issues due to RTT variances, timer granularity, and
1846 * instability in the algorithm which can lead to many false positives and
1847 * create oscillations as well as interact badly with other TCP streams
1848 * implementing the same algorithm.
1849 *
1850 * The second method is to limit the window to the bandwidth delay product
1851 * of the link. This is the method we implement. RTT variances and our
1852 * own manipulation of the congestion window, bwnd, can potentially
1853 * destabilize the algorithm. For this reason we have to stabilize the
1854 * elements used to calculate the window. We do this by using the minimum
1855 * observed RTT, the long term average of the observed bandwidth, and
1856 * by adding two segments worth of slop. It isn't perfect but it is able
1857 * to react to changing conditions and gives us a very stable basis on
1858 * which to extend the algorithm.
1859 */
1860void
1861tcp_xmit_bandwidth_limit(struct tcpcb *tp, tcp_seq ack_seq)
1862{
1863 u_long bw;
1864 u_long bwnd;
1865 int save_ticks;
1866
1867 /*
1868 * If inflight_enable is disabled in the middle of a tcp connection,
1869 * make sure snd_bwnd is effectively disabled.
1870 */
1871 if (tcp_inflight_enable == 0) {
1872 tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT;
1873 tp->snd_bandwidth = 0;
1874 return;
1875 }
1876
1877 /*
1878 * Figure out the bandwidth. Due to the tick granularity this
1879 * is a very rough number and it MUST be averaged over a fairly
1880 * long period of time. XXX we need to take into account a link
1881 * that is not using all available bandwidth, but for now our
1882 * slop will ramp us up if this case occurs and the bandwidth later
1883 * increases.
1884 *
1885 * Note: if ticks rollover 'bw' may wind up negative. We must
1886 * effectively reset t_bw_rtttime for this case.
1887 */
1888 save_ticks = ticks;
1889 if ((u_int)(save_ticks - tp->t_bw_rtttime) < 1)
1890 return;
1891
1892 bw = (int64_t)(ack_seq - tp->t_bw_rtseq) * hz /
1893 (save_ticks - tp->t_bw_rtttime);
1894 tp->t_bw_rtttime = save_ticks;
1895 tp->t_bw_rtseq = ack_seq;
1896 if (tp->t_bw_rtttime == 0 || (int)bw < 0)
1897 return;
1898 bw = ((int64_t)tp->snd_bandwidth * 15 + bw) >> 4;
1899
1900 tp->snd_bandwidth = bw;
1901
1902 /*
1903 * Calculate the semi-static bandwidth delay product, plus two maximal
1904 * segments. The additional slop puts us squarely in the sweet
1905 * spot and also handles the bandwidth run-up case and stabilization.
1906 * Without the slop we could be locking ourselves into a lower
1907 * bandwidth.
1908 *
1909 * Situations Handled:
1910 * (1) Prevents over-queueing of packets on LANs, especially on
1911 * high speed LANs, allowing larger TCP buffers to be
1912 * specified, and also does a good job preventing
1913 * over-queueing of packets over choke points like modems
1914 * (at least for the transmit side).
1915 *
1916 * (2) Is able to handle changing network loads (bandwidth
1917 * drops so bwnd drops, bandwidth increases so bwnd
1918 * increases).
1919 *
1920 * (3) Theoretically should stabilize in the face of multiple
1921 * connections implementing the same algorithm (this may need
1922 * a little work).
1923 *
1924 * (4) Stability value (defaults to 20 = 2 maximal packets) can
1925 * be adjusted with a sysctl but typically only needs to be
1926 * on very slow connections. A value no smaller then 5
1927 * should be used, but only reduce this default if you have
1928 * no other choice.
1929 */
1930#define USERTT ((tp->t_srtt + tp->t_rttbest) / 2)
1931 bwnd = (int64_t)bw * USERTT / (hz << TCP_RTT_SHIFT) + tcp_inflight_stab * tp->t_maxseg / 10;
1932#undef USERTT
1933
1934 if (tcp_inflight_debug > 0) {
1935 static int ltime;
1936 if ((u_int)(ticks - ltime) >= hz / tcp_inflight_debug) {
1937 ltime = ticks;
1938 printf("%p bw %ld rttbest %d srtt %d bwnd %ld\n",
1939 tp,
1940 bw,
1941 tp->t_rttbest,
1942 tp->t_srtt,
1943 bwnd
1944 );
1945 }
1946 }
1947 if ((long)bwnd < tcp_inflight_min)
1948 bwnd = tcp_inflight_min;
1949 if (bwnd > tcp_inflight_max)
1950 bwnd = tcp_inflight_max;
1951 if ((long)bwnd < tp->t_maxseg * 2)
1952 bwnd = tp->t_maxseg * 2;
1953 tp->snd_bwnd = bwnd;
1954}
1955
| 1208 return;
1209
1210 /* if the parameter is from icmp6, decode it. */
1211 if (d != NULL) {
1212 ip6cp = (struct ip6ctlparam *)d;
1213 m = ip6cp->ip6c_m;
1214 ip6 = ip6cp->ip6c_ip6;
1215 off = ip6cp->ip6c_off;
1216 sa6_src = ip6cp->ip6c_src;
1217 } else {
1218 m = NULL;
1219 ip6 = NULL;
1220 off = 0; /* fool gcc */
1221 sa6_src = &sa6_any;
1222 }
1223
1224 if (ip6) {
1225 struct in_conninfo inc;
1226 /*
1227 * XXX: We assume that when IPV6 is non NULL,
1228 * M and OFF are valid.
1229 */
1230
1231 /* check if we can safely examine src and dst ports */
1232 if (m->m_pkthdr.len < off + sizeof(*thp))
1233 return;
1234
1235 bzero(&th, sizeof(th));
1236 m_copydata(m, off, sizeof(*thp), (caddr_t)&th);
1237
1238 in6_pcbnotify(&tcb, sa, th.th_dport,
1239 (struct sockaddr *)ip6cp->ip6c_src,
1240 th.th_sport, cmd, notify);
1241
1242 inc.inc_fport = th.th_dport;
1243 inc.inc_lport = th.th_sport;
1244 inc.inc6_faddr = ((struct sockaddr_in6 *)sa)->sin6_addr;
1245 inc.inc6_laddr = ip6cp->ip6c_src->sin6_addr;
1246 inc.inc_isipv6 = 1;
1247 syncache_unreach(&inc, &th);
1248 } else
1249 in6_pcbnotify(&tcb, sa, 0, (const struct sockaddr *)sa6_src,
1250 0, cmd, notify);
1251}
1252#endif /* INET6 */
1253
1254
1255/*
1256 * Following is where TCP initial sequence number generation occurs.
1257 *
1258 * There are two places where we must use initial sequence numbers:
1259 * 1. In SYN-ACK packets.
1260 * 2. In SYN packets.
1261 *
1262 * All ISNs for SYN-ACK packets are generated by the syncache. See
1263 * tcp_syncache.c for details.
1264 *
1265 * The ISNs in SYN packets must be monotonic; TIME_WAIT recycling
1266 * depends on this property. In addition, these ISNs should be
1267 * unguessable so as to prevent connection hijacking. To satisfy
1268 * the requirements of this situation, the algorithm outlined in
1269 * RFC 1948 is used to generate sequence numbers.
1270 *
1271 * Implementation details:
1272 *
1273 * Time is based off the system timer, and is corrected so that it
1274 * increases by one megabyte per second. This allows for proper
1275 * recycling on high speed LANs while still leaving over an hour
1276 * before rollover.
1277 *
1278 * net.inet.tcp.isn_reseed_interval controls the number of seconds
1279 * between seeding of isn_secret. This is normally set to zero,
1280 * as reseeding should not be necessary.
1281 *
1282 */
1283
1284#define ISN_BYTES_PER_SECOND 1048576
1285
1286u_char isn_secret[32];
1287int isn_last_reseed;
1288MD5_CTX isn_ctx;
1289
1290tcp_seq
1291tcp_new_isn(tp)
1292 struct tcpcb *tp;
1293{
1294 u_int32_t md5_buffer[4];
1295 tcp_seq new_isn;
1296
1297 /* Seed if this is the first use, reseed if requested. */
1298 if ((isn_last_reseed == 0) || ((tcp_isn_reseed_interval > 0) &&
1299 (((u_int)isn_last_reseed + (u_int)tcp_isn_reseed_interval*hz)
1300 < (u_int)ticks))) {
1301 read_random(&isn_secret, sizeof(isn_secret));
1302 isn_last_reseed = ticks;
1303 }
1304
1305 /* Compute the md5 hash and return the ISN. */
1306 MD5Init(&isn_ctx);
1307 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_fport, sizeof(u_short));
1308 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_lport, sizeof(u_short));
1309#ifdef INET6
1310 if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0) {
1311 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_faddr,
1312 sizeof(struct in6_addr));
1313 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_laddr,
1314 sizeof(struct in6_addr));
1315 } else
1316#endif
1317 {
1318 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_faddr,
1319 sizeof(struct in_addr));
1320 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_laddr,
1321 sizeof(struct in_addr));
1322 }
1323 MD5Update(&isn_ctx, (u_char *) &isn_secret, sizeof(isn_secret));
1324 MD5Final((u_char *) &md5_buffer, &isn_ctx);
1325 new_isn = (tcp_seq) md5_buffer[0];
1326 new_isn += ticks * (ISN_BYTES_PER_SECOND / hz);
1327 return new_isn;
1328}
1329
1330/*
1331 * When a source quench is received, close congestion window
1332 * to one segment. We will gradually open it again as we proceed.
1333 */
1334struct inpcb *
1335tcp_quench(inp, errno)
1336 struct inpcb *inp;
1337 int errno;
1338{
1339 struct tcpcb *tp = intotcpcb(inp);
1340
1341 if (tp)
1342 tp->snd_cwnd = tp->t_maxseg;
1343 return (inp);
1344}
1345
1346/*
1347 * When a specific ICMP unreachable message is received and the
1348 * connection state is SYN-SENT, drop the connection. This behavior
1349 * is controlled by the icmp_may_rst sysctl.
1350 */
1351struct inpcb *
1352tcp_drop_syn_sent(inp, errno)
1353 struct inpcb *inp;
1354 int errno;
1355{
1356 struct tcpcb *tp = intotcpcb(inp);
1357
1358 if (tp && tp->t_state == TCPS_SYN_SENT) {
1359 tcp_drop(tp, errno);
1360 return (struct inpcb *)0;
1361 }
1362 return inp;
1363}
1364
1365/*
1366 * When `need fragmentation' ICMP is received, update our idea of the MSS
1367 * based on the new value in the route. Also nudge TCP to send something,
1368 * since we know the packet we just sent was dropped.
1369 * This duplicates some code in the tcp_mss() function in tcp_input.c.
1370 */
1371struct inpcb *
1372tcp_mtudisc(inp, errno)
1373 struct inpcb *inp;
1374 int errno;
1375{
1376 struct tcpcb *tp = intotcpcb(inp);
1377 struct rtentry *rt;
1378 struct rmxp_tao *taop;
1379 struct socket *so = inp->inp_socket;
1380 int offered;
1381 int mss;
1382#ifdef INET6
1383 int isipv6 = (tp->t_inpcb->inp_vflag & INP_IPV6) != 0;
1384#endif /* INET6 */
1385
1386 if (tp) {
1387#ifdef INET6
1388 if (isipv6)
1389 rt = tcp_rtlookup6(&inp->inp_inc);
1390 else
1391#endif /* INET6 */
1392 rt = tcp_rtlookup(&inp->inp_inc);
1393 if (!rt || !rt->rt_rmx.rmx_mtu) {
1394 tp->t_maxopd = tp->t_maxseg =
1395#ifdef INET6
1396 isipv6 ? tcp_v6mssdflt :
1397#endif /* INET6 */
1398 tcp_mssdflt;
1399 return inp;
1400 }
1401 taop = rmx_taop(rt->rt_rmx);
1402 offered = taop->tao_mssopt;
1403 mss = rt->rt_rmx.rmx_mtu -
1404#ifdef INET6
1405 (isipv6 ?
1406 sizeof(struct ip6_hdr) + sizeof(struct tcphdr) :
1407#endif /* INET6 */
1408 sizeof(struct tcpiphdr)
1409#ifdef INET6
1410 )
1411#endif /* INET6 */
1412 ;
1413
1414 if (offered)
1415 mss = min(mss, offered);
1416 /*
1417 * XXX - The above conditional probably violates the TCP
1418 * spec. The problem is that, since we don't know the
1419 * other end's MSS, we are supposed to use a conservative
1420 * default. But, if we do that, then MTU discovery will
1421 * never actually take place, because the conservative
1422 * default is much less than the MTUs typically seen
1423 * on the Internet today. For the moment, we'll sweep
1424 * this under the carpet.
1425 *
1426 * The conservative default might not actually be a problem
1427 * if the only case this occurs is when sending an initial
1428 * SYN with options and data to a host we've never talked
1429 * to before. Then, they will reply with an MSS value which
1430 * will get recorded and the new parameters should get
1431 * recomputed. For Further Study.
1432 */
1433 if (tp->t_maxopd <= mss)
1434 return inp;
1435 tp->t_maxopd = mss;
1436
1437 if ((tp->t_flags & (TF_REQ_TSTMP|TF_NOOPT)) == TF_REQ_TSTMP &&
1438 (tp->t_flags & TF_RCVD_TSTMP) == TF_RCVD_TSTMP)
1439 mss -= TCPOLEN_TSTAMP_APPA;
1440 if ((tp->t_flags & (TF_REQ_CC|TF_NOOPT)) == TF_REQ_CC &&
1441 (tp->t_flags & TF_RCVD_CC) == TF_RCVD_CC)
1442 mss -= TCPOLEN_CC_APPA;
1443#if (MCLBYTES & (MCLBYTES - 1)) == 0
1444 if (mss > MCLBYTES)
1445 mss &= ~(MCLBYTES-1);
1446#else
1447 if (mss > MCLBYTES)
1448 mss = mss / MCLBYTES * MCLBYTES;
1449#endif
1450 if (so->so_snd.sb_hiwat < mss)
1451 mss = so->so_snd.sb_hiwat;
1452
1453 tp->t_maxseg = mss;
1454
1455 tcpstat.tcps_mturesent++;
1456 tp->t_rtttime = 0;
1457 tp->snd_nxt = tp->snd_una;
1458 tcp_output(tp);
1459 }
1460 return inp;
1461}
1462
1463/*
1464 * Look-up the routing entry to the peer of this inpcb. If no route
1465 * is found and it cannot be allocated, then return NULL. This routine
1466 * is called by TCP routines that access the rmx structure and by tcp_mss
1467 * to get the interface MTU.
1468 */
1469struct rtentry *
1470tcp_rtlookup(inc)
1471 struct in_conninfo *inc;
1472{
1473 struct route *ro;
1474 struct rtentry *rt;
1475
1476 ro = &inc->inc_route;
1477 rt = ro->ro_rt;
1478 if (rt == NULL || !(rt->rt_flags & RTF_UP)) {
1479 /* No route yet, so try to acquire one */
1480 if (inc->inc_faddr.s_addr != INADDR_ANY) {
1481 ro->ro_dst.sa_family = AF_INET;
1482 ro->ro_dst.sa_len = sizeof(struct sockaddr_in);
1483 ((struct sockaddr_in *) &ro->ro_dst)->sin_addr =
1484 inc->inc_faddr;
1485 rtalloc(ro);
1486 rt = ro->ro_rt;
1487 }
1488 }
1489 return rt;
1490}
1491
1492#ifdef INET6
1493struct rtentry *
1494tcp_rtlookup6(inc)
1495 struct in_conninfo *inc;
1496{
1497 struct route_in6 *ro6;
1498 struct rtentry *rt;
1499
1500 ro6 = &inc->inc6_route;
1501 rt = ro6->ro_rt;
1502 if (rt == NULL || !(rt->rt_flags & RTF_UP)) {
1503 /* No route yet, so try to acquire one */
1504 if (!IN6_IS_ADDR_UNSPECIFIED(&inc->inc6_faddr)) {
1505 ro6->ro_dst.sin6_family = AF_INET6;
1506 ro6->ro_dst.sin6_len = sizeof(struct sockaddr_in6);
1507 ro6->ro_dst.sin6_addr = inc->inc6_faddr;
1508 rtalloc((struct route *)ro6);
1509 rt = ro6->ro_rt;
1510 }
1511 }
1512 return rt;
1513}
1514#endif /* INET6 */
1515
1516#ifdef IPSEC
1517/* compute ESP/AH header size for TCP, including outer IP header. */
1518size_t
1519ipsec_hdrsiz_tcp(tp)
1520 struct tcpcb *tp;
1521{
1522 struct inpcb *inp;
1523 struct mbuf *m;
1524 size_t hdrsiz;
1525 struct ip *ip;
1526#ifdef INET6
1527 struct ip6_hdr *ip6;
1528#endif
1529 struct tcphdr *th;
1530
1531 if ((tp == NULL) || ((inp = tp->t_inpcb) == NULL))
1532 return 0;
1533 MGETHDR(m, M_DONTWAIT, MT_DATA);
1534 if (!m)
1535 return 0;
1536
1537#ifdef INET6
1538 if ((inp->inp_vflag & INP_IPV6) != 0) {
1539 ip6 = mtod(m, struct ip6_hdr *);
1540 th = (struct tcphdr *)(ip6 + 1);
1541 m->m_pkthdr.len = m->m_len =
1542 sizeof(struct ip6_hdr) + sizeof(struct tcphdr);
1543 tcpip_fillheaders(inp, ip6, th);
1544 hdrsiz = ipsec6_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp);
1545 } else
1546#endif /* INET6 */
1547 {
1548 ip = mtod(m, struct ip *);
1549 th = (struct tcphdr *)(ip + 1);
1550 m->m_pkthdr.len = m->m_len = sizeof(struct tcpiphdr);
1551 tcpip_fillheaders(inp, ip, th);
1552 hdrsiz = ipsec4_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp);
1553 }
1554
1555 m_free(m);
1556 return hdrsiz;
1557}
1558#endif /*IPSEC*/
1559
1560/*
1561 * Return a pointer to the cached information about the remote host.
1562 * The cached information is stored in the protocol specific part of
1563 * the route metrics.
1564 */
1565struct rmxp_tao *
1566tcp_gettaocache(inc)
1567 struct in_conninfo *inc;
1568{
1569 struct rtentry *rt;
1570
1571#ifdef INET6
1572 if (inc->inc_isipv6)
1573 rt = tcp_rtlookup6(inc);
1574 else
1575#endif /* INET6 */
1576 rt = tcp_rtlookup(inc);
1577
1578 /* Make sure this is a host route and is up. */
1579 if (rt == NULL ||
1580 (rt->rt_flags & (RTF_UP|RTF_HOST)) != (RTF_UP|RTF_HOST))
1581 return NULL;
1582
1583 return rmx_taop(rt->rt_rmx);
1584}
1585
1586/*
1587 * Clear all the TAO cache entries, called from tcp_init.
1588 *
1589 * XXX
1590 * This routine is just an empty one, because we assume that the routing
1591 * routing tables are initialized at the same time when TCP, so there is
1592 * nothing in the cache left over.
1593 */
1594static void
1595tcp_cleartaocache()
1596{
1597}
1598
1599/*
1600 * Move a TCP connection into TIME_WAIT state.
1601 * tcbinfo is unlocked.
1602 * inp is locked, and is unlocked before returning.
1603 */
1604void
1605tcp_twstart(tp)
1606 struct tcpcb *tp;
1607{
1608 struct tcptw *tw;
1609 struct inpcb *inp;
1610 int tw_time, acknow;
1611 struct socket *so;
1612
1613 tw = uma_zalloc(tcptw_zone, M_NOWAIT);
1614 if (tw == NULL) {
1615 tw = tcp_timer_2msl_tw(1);
1616 if (tw == NULL) {
1617 tcp_close(tp);
1618 return;
1619 }
1620 }
1621 inp = tp->t_inpcb;
1622 tw->tw_inpcb = inp;
1623
1624 /*
1625 * Recover last window size sent.
1626 */
1627 tw->last_win = (tp->rcv_adv - tp->rcv_nxt) >> tp->rcv_scale;
1628
1629 /*
1630 * Set t_recent if timestamps are used on the connection.
1631 */
1632 if ((tp->t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP|TF_NOOPT)) ==
1633 (TF_REQ_TSTMP|TF_RCVD_TSTMP))
1634 tw->t_recent = tp->ts_recent;
1635 else
1636 tw->t_recent = 0;
1637
1638 tw->snd_nxt = tp->snd_nxt;
1639 tw->rcv_nxt = tp->rcv_nxt;
1640 tw->cc_recv = tp->cc_recv;
1641 tw->cc_send = tp->cc_send;
1642 tw->t_starttime = tp->t_starttime;
1643 tw->tw_time = 0;
1644
1645/* XXX
1646 * If this code will
1647 * be used for fin-wait-2 state also, then we may need
1648 * a ts_recent from the last segment.
1649 */
1650 /* Shorten TIME_WAIT [RFC-1644, p.28] */
1651 if (tp->cc_recv != 0 && (ticks - tp->t_starttime) < tcp_msl) {
1652 tw_time = tp->t_rxtcur * TCPTV_TWTRUNC;
1653 /* For T/TCP client, force ACK now. */
1654 acknow = 1;
1655 } else {
1656 tw_time = 2 * tcp_msl;
1657 acknow = tp->t_flags & TF_ACKNOW;
1658 }
1659 tcp_discardcb(tp);
1660 so = inp->inp_socket;
1661 so->so_pcb = NULL;
1662 tw->tw_cred = crhold(so->so_cred);
1663 tw->tw_so_options = so->so_options;
1664 if (acknow)
1665 tcp_twrespond(tw, so, NULL, TH_ACK);
1666 sotryfree(so);
1667 inp->inp_socket = NULL;
1668 inp->inp_ppcb = (caddr_t)tw;
1669 inp->inp_vflag |= INP_TIMEWAIT;
1670 tcp_timer_2msl_reset(tw, tw_time);
1671 INP_UNLOCK(inp);
1672}
1673
1674struct tcptw *
1675tcp_twclose(struct tcptw *tw, int reuse)
1676{
1677 struct inpcb *inp;
1678
1679 inp = tw->tw_inpcb;
1680 tw->tw_inpcb = NULL;
1681 tcp_timer_2msl_stop(tw);
1682 inp->inp_ppcb = NULL;
1683#ifdef INET6
1684 if (inp->inp_vflag & INP_IPV6PROTO)
1685 in6_pcbdetach(inp);
1686 else
1687#endif
1688 in_pcbdetach(inp);
1689 tcpstat.tcps_closed++;
1690 if (reuse)
1691 return (tw);
1692 uma_zfree(tcptw_zone, tw);
1693 return (NULL);
1694}
1695
1696/*
1697 * One of so and msrc must be non-NULL for use by the MAC Framework to
1698 * construct a label for ay resulting packet.
1699 */
1700int
1701tcp_twrespond(struct tcptw *tw, struct socket *so, struct mbuf *msrc,
1702 int flags)
1703{
1704 struct inpcb *inp = tw->tw_inpcb;
1705 struct tcphdr *th;
1706 struct mbuf *m;
1707 struct ip *ip = NULL;
1708 u_int8_t *optp;
1709 u_int hdrlen, optlen;
1710 int error;
1711#ifdef INET6
1712 struct ip6_hdr *ip6 = NULL;
1713 int isipv6 = inp->inp_inc.inc_isipv6;
1714#endif
1715
1716 KASSERT(so != NULL || msrc != NULL,
1717 ("tcp_twrespond: so and msrc NULL"));
1718
1719 m = m_gethdr(M_DONTWAIT, MT_HEADER);
1720 if (m == NULL)
1721 return (ENOBUFS);
1722 m->m_data += max_linkhdr;
1723
1724#ifdef MAC
1725 if (so != NULL)
1726 mac_create_mbuf_from_socket(so, m);
1727 else
1728 mac_create_mbuf_netlayer(msrc, m);
1729#endif
1730
1731#ifdef INET6
1732 if (isipv6) {
1733 hdrlen = sizeof(struct ip6_hdr) + sizeof(struct tcphdr);
1734 ip6 = mtod(m, struct ip6_hdr *);
1735 th = (struct tcphdr *)(ip6 + 1);
1736 tcpip_fillheaders(inp, ip6, th);
1737 } else
1738#endif
1739 {
1740 hdrlen = sizeof(struct tcpiphdr);
1741 ip = mtod(m, struct ip *);
1742 th = (struct tcphdr *)(ip + 1);
1743 tcpip_fillheaders(inp, ip, th);
1744 }
1745 optp = (u_int8_t *)(th + 1);
1746
1747 /*
1748 * Send a timestamp and echo-reply if both our side and our peer
1749 * have sent timestamps in our SYN's and this is not a RST.
1750 */
1751 if (tw->t_recent && flags == TH_ACK) {
1752 u_int32_t *lp = (u_int32_t *)optp;
1753
1754 /* Form timestamp option as shown in appendix A of RFC 1323. */
1755 *lp++ = htonl(TCPOPT_TSTAMP_HDR);
1756 *lp++ = htonl(ticks);
1757 *lp = htonl(tw->t_recent);
1758 optp += TCPOLEN_TSTAMP_APPA;
1759 }
1760
1761 /*
1762 * Send `CC-family' options if needed, and it's not a RST.
1763 */
1764 if (tw->cc_recv != 0 && flags == TH_ACK) {
1765 u_int32_t *lp = (u_int32_t *)optp;
1766
1767 *lp++ = htonl(TCPOPT_CC_HDR(TCPOPT_CC));
1768 *lp = htonl(tw->cc_send);
1769 optp += TCPOLEN_CC_APPA;
1770 }
1771 optlen = optp - (u_int8_t *)(th + 1);
1772
1773 m->m_len = hdrlen + optlen;
1774 m->m_pkthdr.len = m->m_len;
1775
1776 KASSERT(max_linkhdr + m->m_len <= MHLEN, ("tcptw: mbuf too small"));
1777
1778 th->th_seq = htonl(tw->snd_nxt);
1779 th->th_ack = htonl(tw->rcv_nxt);
1780 th->th_off = (sizeof(struct tcphdr) + optlen) >> 2;
1781 th->th_flags = flags;
1782 th->th_win = htons(tw->last_win);
1783
1784#ifdef INET6
1785 if (isipv6) {
1786 th->th_sum = in6_cksum(m, IPPROTO_TCP, sizeof(struct ip6_hdr),
1787 sizeof(struct tcphdr) + optlen);
1788 ip6->ip6_hlim = in6_selecthlim(inp, inp->in6p_route.ro_rt ?
1789 inp->in6p_route.ro_rt->rt_ifp : NULL);
1790 error = ip6_output(m, inp->in6p_outputopts, &inp->in6p_route,
1791 (tw->tw_so_options & SO_DONTROUTE), NULL, NULL, inp);
1792 } else
1793#endif
1794 {
1795 th->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr,
1796 htons(sizeof(struct tcphdr) + optlen + IPPROTO_TCP));
1797 m->m_pkthdr.csum_flags = CSUM_TCP;
1798 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum);
1799 ip->ip_len = m->m_pkthdr.len;
1800 error = ip_output(m, inp->inp_options, &inp->inp_route,
1801 (tw->tw_so_options & SO_DONTROUTE), NULL, inp);
1802 }
1803 if (flags & TH_ACK)
1804 tcpstat.tcps_sndacks++;
1805 else
1806 tcpstat.tcps_sndctrl++;
1807 tcpstat.tcps_sndtotal++;
1808 return (error);
1809}
1810
1811/*
1812 * TCP BANDWIDTH DELAY PRODUCT WINDOW LIMITING
1813 *
1814 * This code attempts to calculate the bandwidth-delay product as a
1815 * means of determining the optimal window size to maximize bandwidth,
1816 * minimize RTT, and avoid the over-allocation of buffers on interfaces and
1817 * routers. This code also does a fairly good job keeping RTTs in check
1818 * across slow links like modems. We implement an algorithm which is very
1819 * similar (but not meant to be) TCP/Vegas. The code operates on the
1820 * transmitter side of a TCP connection and so only effects the transmit
1821 * side of the connection.
1822 *
1823 * BACKGROUND: TCP makes no provision for the management of buffer space
1824 * at the end points or at the intermediate routers and switches. A TCP
1825 * stream, whether using NewReno or not, will eventually buffer as
1826 * many packets as it is able and the only reason this typically works is
1827 * due to the fairly small default buffers made available for a connection
1828 * (typicaly 16K or 32K). As machines use larger windows and/or window
1829 * scaling it is now fairly easy for even a single TCP connection to blow-out
1830 * all available buffer space not only on the local interface, but on
1831 * intermediate routers and switches as well. NewReno makes a misguided
1832 * attempt to 'solve' this problem by waiting for an actual failure to occur,
1833 * then backing off, then steadily increasing the window again until another
1834 * failure occurs, ad-infinitum. This results in terrible oscillation that
1835 * is only made worse as network loads increase and the idea of intentionally
1836 * blowing out network buffers is, frankly, a terrible way to manage network
1837 * resources.
1838 *
1839 * It is far better to limit the transmit window prior to the failure
1840 * condition being achieved. There are two general ways to do this: First
1841 * you can 'scan' through different transmit window sizes and locate the
1842 * point where the RTT stops increasing, indicating that you have filled the
1843 * pipe, then scan backwards until you note that RTT stops decreasing, then
1844 * repeat ad-infinitum. This method works in principle but has severe
1845 * implementation issues due to RTT variances, timer granularity, and
1846 * instability in the algorithm which can lead to many false positives and
1847 * create oscillations as well as interact badly with other TCP streams
1848 * implementing the same algorithm.
1849 *
1850 * The second method is to limit the window to the bandwidth delay product
1851 * of the link. This is the method we implement. RTT variances and our
1852 * own manipulation of the congestion window, bwnd, can potentially
1853 * destabilize the algorithm. For this reason we have to stabilize the
1854 * elements used to calculate the window. We do this by using the minimum
1855 * observed RTT, the long term average of the observed bandwidth, and
1856 * by adding two segments worth of slop. It isn't perfect but it is able
1857 * to react to changing conditions and gives us a very stable basis on
1858 * which to extend the algorithm.
1859 */
1860void
1861tcp_xmit_bandwidth_limit(struct tcpcb *tp, tcp_seq ack_seq)
1862{
1863 u_long bw;
1864 u_long bwnd;
1865 int save_ticks;
1866
1867 /*
1868 * If inflight_enable is disabled in the middle of a tcp connection,
1869 * make sure snd_bwnd is effectively disabled.
1870 */
1871 if (tcp_inflight_enable == 0) {
1872 tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT;
1873 tp->snd_bandwidth = 0;
1874 return;
1875 }
1876
1877 /*
1878 * Figure out the bandwidth. Due to the tick granularity this
1879 * is a very rough number and it MUST be averaged over a fairly
1880 * long period of time. XXX we need to take into account a link
1881 * that is not using all available bandwidth, but for now our
1882 * slop will ramp us up if this case occurs and the bandwidth later
1883 * increases.
1884 *
1885 * Note: if ticks rollover 'bw' may wind up negative. We must
1886 * effectively reset t_bw_rtttime for this case.
1887 */
1888 save_ticks = ticks;
1889 if ((u_int)(save_ticks - tp->t_bw_rtttime) < 1)
1890 return;
1891
1892 bw = (int64_t)(ack_seq - tp->t_bw_rtseq) * hz /
1893 (save_ticks - tp->t_bw_rtttime);
1894 tp->t_bw_rtttime = save_ticks;
1895 tp->t_bw_rtseq = ack_seq;
1896 if (tp->t_bw_rtttime == 0 || (int)bw < 0)
1897 return;
1898 bw = ((int64_t)tp->snd_bandwidth * 15 + bw) >> 4;
1899
1900 tp->snd_bandwidth = bw;
1901
1902 /*
1903 * Calculate the semi-static bandwidth delay product, plus two maximal
1904 * segments. The additional slop puts us squarely in the sweet
1905 * spot and also handles the bandwidth run-up case and stabilization.
1906 * Without the slop we could be locking ourselves into a lower
1907 * bandwidth.
1908 *
1909 * Situations Handled:
1910 * (1) Prevents over-queueing of packets on LANs, especially on
1911 * high speed LANs, allowing larger TCP buffers to be
1912 * specified, and also does a good job preventing
1913 * over-queueing of packets over choke points like modems
1914 * (at least for the transmit side).
1915 *
1916 * (2) Is able to handle changing network loads (bandwidth
1917 * drops so bwnd drops, bandwidth increases so bwnd
1918 * increases).
1919 *
1920 * (3) Theoretically should stabilize in the face of multiple
1921 * connections implementing the same algorithm (this may need
1922 * a little work).
1923 *
1924 * (4) Stability value (defaults to 20 = 2 maximal packets) can
1925 * be adjusted with a sysctl but typically only needs to be
1926 * on very slow connections. A value no smaller then 5
1927 * should be used, but only reduce this default if you have
1928 * no other choice.
1929 */
1930#define USERTT ((tp->t_srtt + tp->t_rttbest) / 2)
1931 bwnd = (int64_t)bw * USERTT / (hz << TCP_RTT_SHIFT) + tcp_inflight_stab * tp->t_maxseg / 10;
1932#undef USERTT
1933
1934 if (tcp_inflight_debug > 0) {
1935 static int ltime;
1936 if ((u_int)(ticks - ltime) >= hz / tcp_inflight_debug) {
1937 ltime = ticks;
1938 printf("%p bw %ld rttbest %d srtt %d bwnd %ld\n",
1939 tp,
1940 bw,
1941 tp->t_rttbest,
1942 tp->t_srtt,
1943 bwnd
1944 );
1945 }
1946 }
1947 if ((long)bwnd < tcp_inflight_min)
1948 bwnd = tcp_inflight_min;
1949 if (bwnd > tcp_inflight_max)
1950 bwnd = tcp_inflight_max;
1951 if ((long)bwnd < tp->t_maxseg * 2)
1952 bwnd = tp->t_maxseg * 2;
1953 tp->snd_bwnd = bwnd;
1954}
1955
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