2 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995
3 * The Regents of the University of California. All rights reserved.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. All advertising materials mentioning features or use of this software
14 * must display the following acknowledgement:
15 * This product includes software developed by the University of
16 * California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 * may be used to endorse or promote products derived from this software
19 * without specific prior written permission.
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * @(#)tcp_subr.c 8.2 (Berkeley) 5/24/95
37 #include "opt_compat.h"
38 #include "opt_inet6.h"
39 #include "opt_ipsec.h"
41 #include "opt_tcpdebug.h"
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>
49 #include <sys/malloc.h>
52 #include <sys/domain.h>
55 #include <sys/socket.h>
56 #include <sys/socketvar.h>
57 #include <sys/protosw.h>
58 #include <sys/random.h>
62 #include <net/route.h>
65 #include <netinet/in.h>
66 #include <netinet/in_systm.h>
67 #include <netinet/ip.h>
69 #include <netinet/ip6.h>
71 #include <netinet/in_pcb.h>
73 #include <netinet6/in6_pcb.h>
75 #include <netinet/in_var.h>
76 #include <netinet/ip_var.h>
78 #include <netinet6/ip6_var.h>
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>
86 #include <netinet6/tcp6_var.h>
88 #include <netinet/tcpip.h>
90 #include <netinet/tcp_debug.h>
92 #include <netinet6/ip6protosw.h>
95 #include <netinet6/ipsec.h>
97 #include <netinet6/ipsec6.h>
102 #include <netipsec/ipsec.h>
104 #include <netipsec/ipsec6.h>
107 #endif /*FAST_IPSEC*/
109 #include <machine/in_cksum.h>
112 int tcp_mssdflt = TCP_MSS;
113 SYSCTL_INT(_net_inet_tcp, TCPCTL_MSSDFLT, mssdflt, CTLFLAG_RW,
114 &tcp_mssdflt , 0, "Default TCP Maximum Segment Size");
117 int tcp_v6mssdflt = TCP6_MSS;
118 SYSCTL_INT(_net_inet_tcp, TCPCTL_V6MSSDFLT, v6mssdflt,
119 CTLFLAG_RW, &tcp_v6mssdflt , 0,
120 "Default TCP Maximum Segment Size for IPv6");
124 static int tcp_rttdflt = TCPTV_SRTTDFLT / PR_SLOWHZ;
125 SYSCTL_INT(_net_inet_tcp, TCPCTL_RTTDFLT, rttdflt, CTLFLAG_RW,
126 &tcp_rttdflt , 0, "Default maximum TCP Round Trip Time");
129 int tcp_do_rfc1323 = 1;
130 SYSCTL_INT(_net_inet_tcp, TCPCTL_DO_RFC1323, rfc1323, CTLFLAG_RW,
131 &tcp_do_rfc1323 , 0, "Enable rfc1323 (high performance TCP) extensions");
133 int tcp_do_rfc1644 = 0;
134 SYSCTL_INT(_net_inet_tcp, TCPCTL_DO_RFC1644, rfc1644, CTLFLAG_RW,
135 &tcp_do_rfc1644 , 0, "Enable rfc1644 (TTCP) extensions");
137 static int tcp_tcbhashsize = 0;
138 SYSCTL_INT(_net_inet_tcp, OID_AUTO, tcbhashsize, CTLFLAG_RD,
139 &tcp_tcbhashsize, 0, "Size of TCP control-block hashtable");
141 static int do_tcpdrain = 1;
142 SYSCTL_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");
145 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pcbcount, CTLFLAG_RD,
146 &tcbinfo.ipi_count, 0, "Number of active PCBs");
148 static int icmp_may_rst = 1;
149 SYSCTL_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");
152 static int tcp_isn_reseed_interval = 0;
153 SYSCTL_INT(_net_inet_tcp, OID_AUTO, isn_reseed_interval, CTLFLAG_RW,
154 &tcp_isn_reseed_interval, 0, "Seconds between reseeding of ISN secret");
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.
161 static int tcp_inflight_enable = 0;
162 SYSCTL_INT(_net_inet_tcp, OID_AUTO, inflight_enable, CTLFLAG_RW,
163 &tcp_inflight_enable, 0, "Enable automatic TCP inflight data limiting");
165 static int tcp_inflight_debug = 0;
166 SYSCTL_INT(_net_inet_tcp, OID_AUTO, inflight_debug, CTLFLAG_RW,
167 &tcp_inflight_debug, 0, "Debug TCP inflight calculations");
169 static int tcp_inflight_min = 6144;
170 SYSCTL_INT(_net_inet_tcp, OID_AUTO, inflight_min, CTLFLAG_RW,
171 &tcp_inflight_min, 0, "Lower-bound for TCP inflight window");
173 static int tcp_inflight_max = TCP_MAXWIN << TCP_MAX_WINSHIFT;
174 SYSCTL_INT(_net_inet_tcp, OID_AUTO, inflight_max, CTLFLAG_RW,
175 &tcp_inflight_max, 0, "Upper-bound for TCP inflight window");
176 static int tcp_inflight_stab = 20;
177 SYSCTL_INT(_net_inet_tcp, OID_AUTO, inflight_stab, CTLFLAG_RW,
178 &tcp_inflight_stab, 0, "Inflight Algorithm Stabilization 20 = 2 packets");
180 static void tcp_cleartaocache(void);
181 static struct inpcb *tcp_notify(struct inpcb *, int);
182 static void tcp_discardcb(struct tcpcb *);
185 * Target size of TCP PCB hash tables. Must be a power of two.
187 * Note that this can be overridden by the kernel environment
188 * variable net.inet.tcp.tcbhashsize
191 #define TCBHASHSIZE 512
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.
202 struct callout tcpcb_mem_rexmt, tcpcb_mem_persist, tcpcb_mem_keep;
203 struct callout tcpcb_mem_2msl, tcpcb_mem_delack;
206 static uma_zone_t tcpcb_zone;
207 static uma_zone_t tcptw_zone;
215 int hashsize = TCBHASHSIZE;
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;
226 tcp_rexmit_min = TCPTV_MIN;
227 tcp_rexmit_slop = TCPTV_CPU_VAR;
229 INP_INFO_LOCK_INIT(&tcbinfo, "tcp");
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 */
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);
245 #define TCP_MINPROTOHDR (sizeof(struct ip6_hdr) + sizeof(struct tcphdr))
247 #define TCP_MINPROTOHDR (sizeof(struct tcpiphdr))
249 if (max_protohdr < TCP_MINPROTOHDR)
250 max_protohdr = TCP_MINPROTOHDR;
251 if (max_linkhdr + TCP_MINPROTOHDR > MHLEN)
253 #undef TCP_MINPROTOHDR
255 * These have to be type stable for the benefit of the timers.
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);
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.
273 tcpip_fillheaders(inp, ip_ptr, tcp_ptr)
278 struct tcphdr *th = (struct tcphdr *)tcp_ptr;
281 if ((inp->inp_vflag & INP_IPV6) != 0) {
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;
298 ip = (struct ip *)ip_ptr;
299 ip->ip_v = IPVERSION;
301 ip->ip_tos = inp->inp_ip_tos;
305 ip->ip_ttl = inp->inp_ip_ttl;
307 ip->ip_p = IPPROTO_TCP;
308 ip->ip_src = inp->inp_laddr;
309 ip->ip_dst = inp->inp_faddr;
311 th->th_sport = inp->inp_lport;
312 th->th_dport = inp->inp_fport;
320 th->th_sum = 0; /* in_pseudo() is called later for ipv4 */
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.
329 tcpip_maketemplate(inp)
335 m = m_get(M_DONTWAIT, MT_HEADER);
338 m->m_len = sizeof(struct tcptemp);
339 n = mtod(m, struct tcptemp *);
341 tcpip_fillheaders(inp, (void *)&n->tt_ipgen, (void *)&n->tt_t);
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.
354 * In any case the ack and sequence number of the transmitted
355 * segment are as specified by the parameters.
357 * NOTE: If m != NULL, then ti must point to *inside* the mbuf.
360 tcp_respond(tp, ipgen, th, m, ack, seq, flags)
363 register struct tcphdr *th;
364 register struct mbuf *m;
370 struct route *ro = 0;
375 struct route_in6 *ro6 = 0;
376 struct route_in6 sro6;
382 KASSERT(tp != NULL || m != NULL, ("tcp_respond: tp and m both NULL"));
385 isipv6 = ((struct ip *)ipgen)->ip_v == 6;
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;
398 ro6 = &tp->t_inpcb->in6p_route;
401 ro = &tp->t_inpcb->inp_route;
406 bzero(ro6, sizeof *ro6);
411 bzero(ro, sizeof *ro);
415 m = m_gethdr(M_DONTWAIT, MT_HEADER);
419 m->m_data += max_linkhdr;
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);
429 bcopy((caddr_t)ip, mtod(m, caddr_t), sizeof(struct ip));
430 ip = mtod(m, struct ip *);
431 nth = (struct tcphdr *)(ip + 1);
433 bcopy((caddr_t)th, (caddr_t)nth, sizeof(struct tcphdr));
438 m->m_data = (caddr_t)ipgen;
439 /* m_len is set later */
441 #define xchg(a,b,type) { type t; t=a; a=b; b=t; }
444 xchg(ip6->ip6_dst, ip6->ip6_src, struct in6_addr);
445 nth = (struct tcphdr *)(ip6 + 1);
449 xchg(ip->ip_dst.s_addr, ip->ip_src.s_addr, n_long);
450 nth = (struct tcphdr *)(ip + 1);
454 * this is usually a case when an extension header
455 * exists between the IPv6 header and the
458 nth->th_sport = th->th_sport;
459 nth->th_dport = th->th_dport;
461 xchg(nth->th_dport, nth->th_sport, n_short);
467 ip6->ip6_vfc = IPV6_VERSION;
468 ip6->ip6_nxt = IPPROTO_TCP;
469 ip6->ip6_plen = htons((u_short)(sizeof (struct tcphdr) +
471 tlen += sizeof (struct ip6_hdr) + sizeof (struct tcphdr);
475 tlen += sizeof (struct tcpiphdr);
477 ip->ip_ttl = ip_defttl;
480 m->m_pkthdr.len = tlen;
481 m->m_pkthdr.rcvif = (struct ifnet *) 0;
483 if (tp != NULL && tp->t_inpcb != NULL) {
485 * Packet is associated with a socket, so allow the
486 * label of the response to reflect the socket label.
488 mac_create_mbuf_from_socket(tp->t_inpcb->inp_socket, m);
491 * Packet is not associated with a socket, so possibly
492 * update the label in place.
494 mac_reflect_mbuf_tcp(m);
497 nth->th_seq = htonl(seq);
498 nth->th_ack = htonl(ack);
500 nth->th_off = sizeof (struct tcphdr) >> 2;
501 nth->th_flags = flags;
503 nth->th_win = htons((u_short) (win >> tp->rcv_scale));
505 nth->th_win = htons((u_short)win);
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,
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);
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);
531 (void)ip6_output(m, NULL, ro6, ipflags, NULL, NULL,
532 tp ? tp->t_inpcb : NULL);
533 if (ro6 == &sro6 && ro6->ro_rt) {
540 (void) ip_output(m, NULL, ro, ipflags, NULL, tp ? tp->t_inpcb : NULL);
541 if (ro == &sro && ro->ro_rt) {
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().
558 struct tcpcb_mem *tm;
561 int isipv6 = (inp->inp_vflag & INP_IPV6) != 0;
564 tm = uma_zalloc(tcpcb_zone, M_NOWAIT | M_ZERO);
568 /* LIST_INIT(&tp->t_segq); */ /* XXX covered by M_ZERO */
569 tp->t_maxseg = tp->t_maxopd =
571 isipv6 ? tcp_v6mssdflt :
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);
583 tp->t_flags = (TF_REQ_SCALE|TF_REQ_TSTMP);
585 tp->t_flags |= TF_REQ_CC;
586 tp->t_inpcb = inp; /* XXX */
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.
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;
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.
606 inp->inp_ip_ttl = ip_defttl;
607 inp->inp_ppcb = (caddr_t)tp;
608 return (tp); /* XXX */
612 * Drop a TCP connection, reporting
613 * the specified error. If connection is synchronized,
614 * then send a RST to peer.
618 register struct tcpcb *tp;
621 struct socket *so = tp->t_inpcb->inp_socket;
623 if (TCPS_HAVERCVDSYN(tp->t_state)) {
624 tp->t_state = TCPS_CLOSED;
625 (void) tcp_output(tp);
626 tcpstat.tcps_drops++;
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));
640 struct inpcb *inp = tp->t_inpcb;
641 struct socket *so = inp->inp_socket;
643 int isipv6 = (inp->inp_vflag & INP_IPV6) != 0;
649 * Make sure that all of our timers are stopped before we
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);
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.
666 * Don't update the default route's characteristics and don't
667 * update anything that the user "locked".
669 if (tp->t_rttupdated >= 16) {
670 register u_long i = 0;
673 struct sockaddr_in6 *sin6;
675 if ((rt = inp->in6p_route.ro_rt) == NULL)
677 sin6 = (struct sockaddr_in6 *)rt_key(rt);
678 if (IN6_IS_ADDR_UNSPECIFIED(&sin6->sin6_addr))
683 if ((rt = inp->inp_route.ro_rt) == NULL ||
684 ((struct sockaddr_in *)rt_key(rt))->sin_addr.s_addr
688 if ((rt->rt_rmx.rmx_locks & RTV_RTT) == 0) {
690 (RTM_RTTUNIT / (hz * TCP_RTT_SCALE));
691 if (rt->rt_rmx.rmx_rtt && i)
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.
699 (rt->rt_rmx.rmx_rtt + i) / 2;
701 rt->rt_rmx.rmx_rtt = i;
702 tcpstat.tcps_cachedrtt++;
704 if ((rt->rt_rmx.rmx_locks & RTV_RTTVAR) == 0) {
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;
711 rt->rt_rmx.rmx_rttvar = i;
712 tcpstat.tcps_cachedrttvar++;
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
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.
728 i = tp->snd_ssthresh;
729 if (rt->rt_rmx.rmx_sendpipe != 0)
730 dosavessthresh = (i < rt->rt_rmx.rmx_sendpipe / 2);
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)
737 * convert the limit from user data bytes to
738 * packets then to packet data bytes.
740 i = (i + tp->t_maxseg / 2) / tp->t_maxseg;
743 i *= (u_long)(tp->t_maxseg +
745 (isipv6 ? sizeof (struct ip6_hdr) +
746 sizeof (struct tcphdr) :
748 sizeof (struct tcpiphdr)
753 if (rt->rt_rmx.rmx_ssthresh)
754 rt->rt_rmx.rmx_ssthresh =
755 (rt->rt_rmx.rmx_ssthresh + i) / 2;
757 rt->rt_rmx.rmx_ssthresh = i;
758 tcpstat.tcps_cachedssthresh++;
762 /* free the reassembly queue, if any */
763 while ((q = LIST_FIRST(&tp->t_segq)) != NULL) {
764 LIST_REMOVE(q, tqe_q);
768 inp->inp_ppcb = NULL;
770 uma_zfree(tcpcb_zone, tp);
771 soisdisconnected(so);
775 * Close a TCP control block:
776 * discard all space held by the tcp
777 * discard internet protocol block
778 * wake up any sleepers
784 struct inpcb *inp = tp->t_inpcb;
786 struct socket *so = inp->inp_socket;
791 if (INP_CHECK_SOCKAF(so, AF_INET6))
796 tcpstat.tcps_closed++;
797 return ((struct tcpcb *)0);
807 struct tseg_qent *te;
810 * Walk the tcpbs, if existing, and flush the reassembly queue,
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
817 INP_INFO_RLOCK(&tcbinfo);
818 LIST_FOREACH(inpb, tcbinfo.listhead, inp_list) {
819 if (inpb->inp_vflag & INP_TIMEWAIT)
822 if ((tcpb = intotcpcb(inpb))) {
823 while ((te = LIST_FIRST(&tcpb->t_segq))
825 LIST_REMOVE(te, tqe_q);
832 INP_INFO_RUNLOCK(&tcbinfo);
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).
841 * Do not wake up user since there currently is no mechanism for
842 * reporting soft errors (yet - a kqueue filter may be added).
844 static struct inpcb *
845 tcp_notify(inp, error)
849 struct tcpcb *tp = (struct tcpcb *)inp->inp_ppcb;
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.
858 if (tp->t_state == TCPS_ESTABLISHED &&
859 (error == EHOSTUNREACH || error == ENETUNREACH ||
860 error == EHOSTDOWN)) {
862 } else if (tp->t_state < TCPS_ESTABLISHED && tp->t_rxtshift > 3 &&
865 return (struct inpcb *)0;
867 tp->t_softerror = error;
871 wakeup( &so->so_timeo);
878 tcp_pcblist(SYSCTL_HANDLER_ARGS)
881 struct inpcb *inp, **inp_list;
886 * The process of preparing the TCB list is too time-consuming and
887 * resource-intensive to repeat twice on every request.
889 if (req->oldptr == 0) {
890 n = tcbinfo.ipi_count;
891 req->oldidx = 2 * (sizeof xig)
892 + (n + n/8) * sizeof(struct xtcpcb);
896 if (req->newptr != 0)
900 * OK, now we're committed to doing something.
903 INP_INFO_RLOCK(&tcbinfo);
904 gencnt = tcbinfo.ipi_gencnt;
905 n = tcbinfo.ipi_count;
906 INP_INFO_RUNLOCK(&tcbinfo);
909 sysctl_wire_old_buffer(req, 2 * (sizeof xig)
910 + n * sizeof(struct xtcpcb));
912 xig.xig_len = sizeof xig;
914 xig.xig_gen = gencnt;
915 xig.xig_sogen = so_gencnt;
916 error = SYSCTL_OUT(req, &xig, sizeof xig);
920 inp_list = malloc(n * sizeof *inp_list, M_TEMP, M_WAITOK);
925 INP_INFO_RLOCK(&tcbinfo);
926 for (inp = LIST_FIRST(tcbinfo.listhead), i = 0; inp && i < n;
927 inp = LIST_NEXT(inp, inp_list)) {
929 if (inp->inp_gencnt <= gencnt) {
931 * XXX: This use of cr_cansee(), introduced with
932 * TCP state changes, is not quite right, but for
933 * now, better than nothing.
935 if (inp->inp_vflag & INP_TIMEWAIT)
936 error = cr_cansee(req->td->td_ucred,
937 intotw(inp)->tw_cred);
939 error = cr_canseesocket(req->td->td_ucred,
946 INP_INFO_RUNLOCK(&tcbinfo);
951 for (i = 0; i < n; i++) {
953 if (inp->inp_gencnt <= gencnt) {
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;
966 bcopy(inp_ppcb, &xt.xt_tp, sizeof xt.xt_tp);
968 sotoxsocket(inp->inp_socket, &xt.xt_socket);
970 bzero(&xt.xt_socket, sizeof xt.xt_socket);
971 xt.xt_socket.xso_protocol = IPPROTO_TCP;
973 xt.xt_inp.inp_gencnt = inp->inp_gencnt;
974 error = SYSCTL_OUT(req, &xt, sizeof xt);
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.
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);
992 error = SYSCTL_OUT(req, &xig, sizeof xig);
994 free(inp_list, M_TEMP);
998 SYSCTL_PROC(_net_inet_tcp, TCPCTL_PCBLIST, pcblist, CTLFLAG_RD, 0, 0,
999 tcp_pcblist, "S,xtcpcb", "List of active TCP connections");
1002 tcp_getcred(SYSCTL_HANDLER_ARGS)
1005 struct sockaddr_in addrs[2];
1009 error = suser_cred(req->td->td_ucred, PRISON_ROOT);
1012 error = SYSCTL_IN(req, addrs, sizeof(addrs));
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);
1024 if (inp->inp_socket == NULL) {
1028 error = cr_canseesocket(req->td->td_ucred, inp->inp_socket);
1031 cru2x(inp->inp_socket->so_cred, &xuc);
1035 INP_INFO_RUNLOCK(&tcbinfo);
1038 error = SYSCTL_OUT(req, &xuc, sizeof(struct xucred));
1042 SYSCTL_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");
1048 tcp6_getcred(SYSCTL_HANDLER_ARGS)
1051 struct sockaddr_in6 addrs[2];
1053 int error, s, mapped = 0;
1055 error = suser_cred(req->td->td_ucred, PRISON_ROOT);
1058 error = SYSCTL_IN(req, addrs, sizeof(addrs));
1061 if (IN6_IS_ADDR_V4MAPPED(&addrs[0].sin6_addr)) {
1062 if (IN6_IS_ADDR_V4MAPPED(&addrs[1].sin6_addr))
1068 INP_INFO_RLOCK(&tcbinfo);
1070 inp = in_pcblookup_hash(&tcbinfo,
1071 *(struct in_addr *)&addrs[1].sin6_addr.s6_addr[12],
1073 *(struct in_addr *)&addrs[0].sin6_addr.s6_addr[12],
1077 inp = in6_pcblookup_hash(&tcbinfo, &addrs[1].sin6_addr,
1079 &addrs[0].sin6_addr, addrs[0].sin6_port,
1086 if (inp->inp_socket == NULL) {
1090 error = cr_canseesocket(req->td->td_ucred, inp->inp_socket);
1093 cru2x(inp->inp_socket->so_cred, &xuc);
1097 INP_INFO_RUNLOCK(&tcbinfo);
1100 error = SYSCTL_OUT(req, &xuc, sizeof(struct xucred));
1104 SYSCTL_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");
1111 tcp_ctlinput(cmd, sa, vip)
1113 struct sockaddr *sa;
1116 struct ip *ip = vip;
1118 struct in_addr faddr;
1121 struct inpcb *(*notify)(struct inpcb *, int) = tcp_notify;
1125 faddr = ((struct sockaddr_in *)sa)->sin_addr;
1126 if (sa->sa_family != AF_INET || faddr.s_addr == INADDR_ANY)
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)) {
1138 notify = in_rtchange;
1139 } else if (cmd == PRC_HOSTDEAD)
1141 else if ((unsigned)cmd > PRC_NCMDS || inetctlerrmap[cmd] == 0)
1145 th = (struct tcphdr *)((caddr_t)ip
1146 + (ip->ip_hl << 2));
1147 INP_INFO_WLOCK(&tcbinfo);
1148 inp = in_pcblookup_hash(&tcbinfo, faddr, th->th_dport,
1149 ip->ip_src, th->th_sport, 0, NULL);
1152 if (inp->inp_socket != NULL) {
1153 icmp_seq = htonl(th->th_seq);
1154 tp = intotcpcb(inp);
1155 if (SEQ_GEQ(icmp_seq, tp->snd_una) &&
1156 SEQ_LT(icmp_seq, tp->snd_max))
1157 inp = (*notify)(inp, inetctlerrmap[cmd]);
1162 struct in_conninfo inc;
1164 inc.inc_fport = th->th_dport;
1165 inc.inc_lport = th->th_sport;
1166 inc.inc_faddr = faddr;
1167 inc.inc_laddr = ip->ip_src;
1171 syncache_unreach(&inc, th);
1173 INP_INFO_WUNLOCK(&tcbinfo);
1176 in_pcbnotifyall(&tcbinfo, faddr, inetctlerrmap[cmd], notify);
1181 tcp6_ctlinput(cmd, sa, d)
1183 struct sockaddr *sa;
1187 struct inpcb *(*notify)(struct inpcb *, int) = tcp_notify;
1188 struct ip6_hdr *ip6;
1190 struct ip6ctlparam *ip6cp = NULL;
1191 const struct sockaddr_in6 *sa6_src = NULL;
1193 struct tcp_portonly {
1198 if (sa->sa_family != AF_INET6 ||
1199 sa->sa_len != sizeof(struct sockaddr_in6))
1202 if (cmd == PRC_QUENCH)
1203 notify = tcp_quench;
1204 else if (cmd == PRC_MSGSIZE)
1205 notify = tcp_mtudisc;
1206 else if (!PRC_IS_REDIRECT(cmd) &&
1207 ((unsigned)cmd > PRC_NCMDS || inet6ctlerrmap[cmd] == 0))
1210 /* if the parameter is from icmp6, decode it. */
1212 ip6cp = (struct ip6ctlparam *)d;
1214 ip6 = ip6cp->ip6c_ip6;
1215 off = ip6cp->ip6c_off;
1216 sa6_src = ip6cp->ip6c_src;
1220 off = 0; /* fool gcc */
1225 struct in_conninfo inc;
1227 * XXX: We assume that when IPV6 is non NULL,
1228 * M and OFF are valid.
1231 /* check if we can safely examine src and dst ports */
1232 if (m->m_pkthdr.len < off + sizeof(*thp))
1235 bzero(&th, sizeof(th));
1236 m_copydata(m, off, sizeof(*thp), (caddr_t)&th);
1238 in6_pcbnotify(&tcb, sa, th.th_dport,
1239 (struct sockaddr *)ip6cp->ip6c_src,
1240 th.th_sport, cmd, notify);
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;
1247 syncache_unreach(&inc, &th);
1249 in6_pcbnotify(&tcb, sa, 0, (const struct sockaddr *)sa6_src,
1256 * Following is where TCP initial sequence number generation occurs.
1258 * There are two places where we must use initial sequence numbers:
1259 * 1. In SYN-ACK packets.
1260 * 2. In SYN packets.
1262 * All ISNs for SYN-ACK packets are generated by the syncache. See
1263 * tcp_syncache.c for details.
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.
1271 * Implementation details:
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
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.
1284 #define ISN_BYTES_PER_SECOND 1048576
1286 u_char isn_secret[32];
1287 int isn_last_reseed;
1294 u_int32_t md5_buffer[4];
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)
1301 read_random(&isn_secret, sizeof(isn_secret));
1302 isn_last_reseed = ticks;
1305 /* Compute the md5 hash and return the ISN. */
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));
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));
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));
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);
1331 * When a source quench is received, close congestion window
1332 * to one segment. We will gradually open it again as we proceed.
1335 tcp_quench(inp, errno)
1339 struct tcpcb *tp = intotcpcb(inp);
1342 tp->snd_cwnd = tp->t_maxseg;
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.
1352 tcp_drop_syn_sent(inp, errno)
1356 struct tcpcb *tp = intotcpcb(inp);
1358 if (tp && tp->t_state == TCPS_SYN_SENT) {
1359 tcp_drop(tp, errno);
1360 return (struct inpcb *)0;
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.
1372 tcp_mtudisc(inp, errno)
1376 struct tcpcb *tp = intotcpcb(inp);
1378 struct rmxp_tao *taop;
1379 struct socket *so = inp->inp_socket;
1383 int isipv6 = (tp->t_inpcb->inp_vflag & INP_IPV6) != 0;
1389 rt = tcp_rtlookup6(&inp->inp_inc);
1392 rt = tcp_rtlookup(&inp->inp_inc);
1393 if (!rt || !rt->rt_rmx.rmx_mtu) {
1394 tp->t_maxopd = tp->t_maxseg =
1396 isipv6 ? tcp_v6mssdflt :
1401 taop = rmx_taop(rt->rt_rmx);
1402 offered = taop->tao_mssopt;
1403 mss = rt->rt_rmx.rmx_mtu -
1406 sizeof(struct ip6_hdr) + sizeof(struct tcphdr) :
1408 sizeof(struct tcpiphdr)
1415 mss = min(mss, offered);
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.
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.
1433 if (tp->t_maxopd <= mss)
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
1445 mss &= ~(MCLBYTES-1);
1448 mss = mss / MCLBYTES * MCLBYTES;
1450 if (so->so_snd.sb_hiwat < mss)
1451 mss = so->so_snd.sb_hiwat;
1455 tcpstat.tcps_mturesent++;
1457 tp->snd_nxt = tp->snd_una;
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.
1471 struct in_conninfo *inc;
1476 ro = &inc->inc_route;
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 =
1495 struct in_conninfo *inc;
1497 struct route_in6 *ro6;
1500 ro6 = &inc->inc6_route;
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);
1517 /* compute ESP/AH header size for TCP, including outer IP header. */
1519 ipsec_hdrsiz_tcp(tp)
1527 struct ip6_hdr *ip6;
1531 if ((tp == NULL) || ((inp = tp->t_inpcb) == NULL))
1533 MGETHDR(m, M_DONTWAIT, MT_DATA);
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);
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);
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.
1566 tcp_gettaocache(inc)
1567 struct in_conninfo *inc;
1572 if (inc->inc_isipv6)
1573 rt = tcp_rtlookup6(inc);
1576 rt = tcp_rtlookup(inc);
1578 /* Make sure this is a host route and is up. */
1580 (rt->rt_flags & (RTF_UP|RTF_HOST)) != (RTF_UP|RTF_HOST))
1583 return rmx_taop(rt->rt_rmx);
1587 * Clear all the TAO cache entries, called from tcp_init.
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.
1600 * Move a TCP connection into TIME_WAIT state.
1601 * tcbinfo is unlocked.
1602 * inp is locked, and is unlocked before returning.
1610 int tw_time, acknow;
1613 tw = uma_zalloc(tcptw_zone, M_NOWAIT);
1615 tw = tcp_timer_2msl_tw(1);
1625 * Recover last window size sent.
1627 tw->last_win = (tp->rcv_adv - tp->rcv_nxt) >> tp->rcv_scale;
1630 * Set t_recent if timestamps are used on the connection.
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;
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;
1647 * be used for fin-wait-2 state also, then we may need
1648 * a ts_recent from the last segment.
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. */
1656 tw_time = 2 * tcp_msl;
1657 acknow = tp->t_flags & TF_ACKNOW;
1660 so = inp->inp_socket;
1662 tw->tw_cred = crhold(so->so_cred);
1663 tw->tw_so_options = so->so_options;
1665 tcp_twrespond(tw, so, NULL, TH_ACK);
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);
1675 tcp_twclose(struct tcptw *tw, int reuse)
1680 tw->tw_inpcb = NULL;
1681 tcp_timer_2msl_stop(tw);
1682 inp->inp_ppcb = NULL;
1684 if (inp->inp_vflag & INP_IPV6PROTO)
1689 tcpstat.tcps_closed++;
1692 uma_zfree(tcptw_zone, tw);
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.
1701 tcp_twrespond(struct tcptw *tw, struct socket *so, struct mbuf *msrc,
1704 struct inpcb *inp = tw->tw_inpcb;
1707 struct ip *ip = NULL;
1709 u_int hdrlen, optlen;
1712 struct ip6_hdr *ip6 = NULL;
1713 int isipv6 = inp->inp_inc.inc_isipv6;
1716 KASSERT(so != NULL || msrc != NULL,
1717 ("tcp_twrespond: so and msrc NULL"));
1719 m = m_gethdr(M_DONTWAIT, MT_HEADER);
1722 m->m_data += max_linkhdr;
1726 mac_create_mbuf_from_socket(so, m);
1728 mac_create_mbuf_netlayer(msrc, m);
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);
1740 hdrlen = sizeof(struct tcpiphdr);
1741 ip = mtod(m, struct ip *);
1742 th = (struct tcphdr *)(ip + 1);
1743 tcpip_fillheaders(inp, ip, th);
1745 optp = (u_int8_t *)(th + 1);
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.
1751 if (tw->t_recent && flags == TH_ACK) {
1752 u_int32_t *lp = (u_int32_t *)optp;
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;
1762 * Send `CC-family' options if needed, and it's not a RST.
1764 if (tw->cc_recv != 0 && flags == TH_ACK) {
1765 u_int32_t *lp = (u_int32_t *)optp;
1767 *lp++ = htonl(TCPOPT_CC_HDR(TCPOPT_CC));
1768 *lp = htonl(tw->cc_send);
1769 optp += TCPOLEN_CC_APPA;
1771 optlen = optp - (u_int8_t *)(th + 1);
1773 m->m_len = hdrlen + optlen;
1774 m->m_pkthdr.len = m->m_len;
1776 KASSERT(max_linkhdr + m->m_len <= MHLEN, ("tcptw: mbuf too small"));
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);
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);
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);
1804 tcpstat.tcps_sndacks++;
1806 tcpstat.tcps_sndctrl++;
1807 tcpstat.tcps_sndtotal++;
1812 * TCP BANDWIDTH DELAY PRODUCT WINDOW LIMITING
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.
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
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.
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.
1861 tcp_xmit_bandwidth_limit(struct tcpcb *tp, tcp_seq ack_seq)
1868 * If inflight_enable is disabled in the middle of a tcp connection,
1869 * make sure snd_bwnd is effectively disabled.
1871 if (tcp_inflight_enable == 0) {
1872 tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT;
1873 tp->snd_bandwidth = 0;
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
1885 * Note: if ticks rollover 'bw' may wind up negative. We must
1886 * effectively reset t_bw_rtttime for this case.
1889 if ((u_int)(save_ticks - tp->t_bw_rtttime) < 1)
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)
1898 bw = ((int64_t)tp->snd_bandwidth * 15 + bw) >> 4;
1900 tp->snd_bandwidth = bw;
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
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).
1916 * (2) Is able to handle changing network loads (bandwidth
1917 * drops so bwnd drops, bandwidth increases so bwnd
1920 * (3) Theoretically should stabilize in the face of multiple
1921 * connections implementing the same algorithm (this may need
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
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;
1934 if (tcp_inflight_debug > 0) {
1936 if ((u_int)(ticks - ltime) >= hz / tcp_inflight_debug) {
1938 printf("%p bw %ld rttbest %d srtt %d bwnd %ld\n",
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;