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[dragonfly.git] / sys / netinet / tcp_subr.c
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1 /*
2 * Copyright (c) 2003, 2004 Jeffrey M. Hsu. All rights reserved.
3 * Copyright (c) 2003, 2004 The DragonFly Project. All rights reserved.
5 * This code is derived from software contributed to The DragonFly Project
6 * by Jeffrey M. Hsu.
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. Neither the name of The DragonFly Project nor the names of its
17 * contributors may be used to endorse or promote products derived
18 * from this software without specific, prior written permission.
20 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
21 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
22 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
23 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
24 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
25 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
26 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
27 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
28 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
29 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
30 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
35 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995
36 * The Regents of the University of California. All rights reserved.
38 * Redistribution and use in source and binary forms, with or without
39 * modification, are permitted provided that the following conditions
40 * are met:
41 * 1. Redistributions of source code must retain the above copyright
42 * notice, this list of conditions and the following disclaimer.
43 * 2. Redistributions in binary form must reproduce the above copyright
44 * notice, this list of conditions and the following disclaimer in the
45 * documentation and/or other materials provided with the distribution.
46 * 3. All advertising materials mentioning features or use of this software
47 * must display the following acknowledgement:
48 * This product includes software developed by the University of
49 * California, Berkeley and its contributors.
50 * 4. Neither the name of the University nor the names of its contributors
51 * may be used to endorse or promote products derived from this software
52 * without specific prior written permission.
54 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
55 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
56 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
57 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
58 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
59 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
60 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
61 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
62 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
63 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
64 * SUCH DAMAGE.
66 * @(#)tcp_subr.c 8.2 (Berkeley) 5/24/95
67 * $FreeBSD: src/sys/netinet/tcp_subr.c,v 1.73.2.31 2003/01/24 05:11:34 sam Exp $
68 * $DragonFly: src/sys/netinet/tcp_subr.c,v 1.59 2007/07/06 11:59:03 sephe Exp $
71 #include "opt_compat.h"
72 #include "opt_inet6.h"
73 #include "opt_ipsec.h"
74 #include "opt_tcpdebug.h"
76 #include <sys/param.h>
77 #include <sys/systm.h>
78 #include <sys/callout.h>
79 #include <sys/kernel.h>
80 #include <sys/sysctl.h>
81 #include <sys/malloc.h>
82 #include <sys/mpipe.h>
83 #include <sys/mbuf.h>
84 #ifdef INET6
85 #include <sys/domain.h>
86 #endif
87 #include <sys/proc.h>
88 #include <sys/socket.h>
89 #include <sys/socketvar.h>
90 #include <sys/protosw.h>
91 #include <sys/random.h>
92 #include <sys/in_cksum.h>
93 #include <sys/ktr.h>
95 #include <vm/vm_zone.h>
97 #include <net/route.h>
98 #include <net/if.h>
99 #include <net/netisr.h>
101 #define _IP_VHL
102 #include <netinet/in.h>
103 #include <netinet/in_systm.h>
104 #include <netinet/ip.h>
105 #include <netinet/ip6.h>
106 #include <netinet/in_pcb.h>
107 #include <netinet6/in6_pcb.h>
108 #include <netinet/in_var.h>
109 #include <netinet/ip_var.h>
110 #include <netinet6/ip6_var.h>
111 #include <netinet/ip_icmp.h>
112 #ifdef INET6
113 #include <netinet/icmp6.h>
114 #endif
115 #include <netinet/tcp.h>
116 #include <netinet/tcp_fsm.h>
117 #include <netinet/tcp_seq.h>
118 #include <netinet/tcp_timer.h>
119 #include <netinet/tcp_var.h>
120 #include <netinet6/tcp6_var.h>
121 #include <netinet/tcpip.h>
122 #ifdef TCPDEBUG
123 #include <netinet/tcp_debug.h>
124 #endif
125 #include <netinet6/ip6protosw.h>
127 #ifdef IPSEC
128 #include <netinet6/ipsec.h>
129 #ifdef INET6
130 #include <netinet6/ipsec6.h>
131 #endif
132 #endif
134 #ifdef FAST_IPSEC
135 #include <netproto/ipsec/ipsec.h>
136 #ifdef INET6
137 #include <netproto/ipsec/ipsec6.h>
138 #endif
139 #define IPSEC
140 #endif
142 #include <sys/md5.h>
143 #include <sys/msgport2.h>
144 #include <machine/smp.h>
146 #include <net/netmsg2.h>
148 #if !defined(KTR_TCP)
149 #define KTR_TCP KTR_ALL
150 #endif
151 KTR_INFO_MASTER(tcp);
152 KTR_INFO(KTR_TCP, tcp, rxmsg, 0, "tcp getmsg", 0);
153 KTR_INFO(KTR_TCP, tcp, wait, 1, "tcp waitmsg", 0);
154 KTR_INFO(KTR_TCP, tcp, delayed, 2, "tcp execute delayed ops", 0);
155 #define logtcp(name) KTR_LOG(tcp_ ## name)
157 struct inpcbinfo tcbinfo[MAXCPU];
158 struct tcpcbackqhead tcpcbackq[MAXCPU];
160 int tcp_mssdflt = TCP_MSS;
161 SYSCTL_INT(_net_inet_tcp, TCPCTL_MSSDFLT, mssdflt, CTLFLAG_RW,
162 &tcp_mssdflt, 0, "Default TCP Maximum Segment Size");
164 #ifdef INET6
165 int tcp_v6mssdflt = TCP6_MSS;
166 SYSCTL_INT(_net_inet_tcp, TCPCTL_V6MSSDFLT, v6mssdflt, CTLFLAG_RW,
167 &tcp_v6mssdflt, 0, "Default TCP Maximum Segment Size for IPv6");
168 #endif
170 #if 0
171 static int tcp_rttdflt = TCPTV_SRTTDFLT / PR_SLOWHZ;
172 SYSCTL_INT(_net_inet_tcp, TCPCTL_RTTDFLT, rttdflt, CTLFLAG_RW,
173 &tcp_rttdflt, 0, "Default maximum TCP Round Trip Time");
174 #endif
176 int tcp_do_rfc1323 = 1;
177 SYSCTL_INT(_net_inet_tcp, TCPCTL_DO_RFC1323, rfc1323, CTLFLAG_RW,
178 &tcp_do_rfc1323, 0, "Enable rfc1323 (high performance TCP) extensions");
180 int tcp_do_rfc1644 = 0;
181 SYSCTL_INT(_net_inet_tcp, TCPCTL_DO_RFC1644, rfc1644, CTLFLAG_RW,
182 &tcp_do_rfc1644, 0, "Enable rfc1644 (TTCP) extensions");
184 static int tcp_tcbhashsize = 0;
185 SYSCTL_INT(_net_inet_tcp, OID_AUTO, tcbhashsize, CTLFLAG_RD,
186 &tcp_tcbhashsize, 0, "Size of TCP control block hashtable");
188 static int do_tcpdrain = 1;
189 SYSCTL_INT(_net_inet_tcp, OID_AUTO, do_tcpdrain, CTLFLAG_RW, &do_tcpdrain, 0,
190 "Enable tcp_drain routine for extra help when low on mbufs");
192 /* XXX JH */
193 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pcbcount, CTLFLAG_RD,
194 &tcbinfo[0].ipi_count, 0, "Number of active PCBs");
196 static int icmp_may_rst = 1;
197 SYSCTL_INT(_net_inet_tcp, OID_AUTO, icmp_may_rst, CTLFLAG_RW, &icmp_may_rst, 0,
198 "Certain ICMP unreachable messages may abort connections in SYN_SENT");
200 static int tcp_isn_reseed_interval = 0;
201 SYSCTL_INT(_net_inet_tcp, OID_AUTO, isn_reseed_interval, CTLFLAG_RW,
202 &tcp_isn_reseed_interval, 0, "Seconds between reseeding of ISN secret");
205 * TCP bandwidth limiting sysctls. Note that the default lower bound of
206 * 1024 exists only for debugging. A good production default would be
207 * something like 6100.
209 static int tcp_inflight_enable = 0;
210 SYSCTL_INT(_net_inet_tcp, OID_AUTO, inflight_enable, CTLFLAG_RW,
211 &tcp_inflight_enable, 0, "Enable automatic TCP inflight data limiting");
213 static int tcp_inflight_debug = 0;
214 SYSCTL_INT(_net_inet_tcp, OID_AUTO, inflight_debug, CTLFLAG_RW,
215 &tcp_inflight_debug, 0, "Debug TCP inflight calculations");
217 static int tcp_inflight_min = 6144;
218 SYSCTL_INT(_net_inet_tcp, OID_AUTO, inflight_min, CTLFLAG_RW,
219 &tcp_inflight_min, 0, "Lower bound for TCP inflight window");
221 static int tcp_inflight_max = TCP_MAXWIN << TCP_MAX_WINSHIFT;
222 SYSCTL_INT(_net_inet_tcp, OID_AUTO, inflight_max, CTLFLAG_RW,
223 &tcp_inflight_max, 0, "Upper bound for TCP inflight window");
225 static int tcp_inflight_stab = 20;
226 SYSCTL_INT(_net_inet_tcp, OID_AUTO, inflight_stab, CTLFLAG_RW,
227 &tcp_inflight_stab, 0, "Slop in maximal packets / 10 (20 = 2 packets)");
229 static MALLOC_DEFINE(M_TCPTEMP, "tcptemp", "TCP Templates for Keepalives");
230 static struct malloc_pipe tcptemp_mpipe;
232 static void tcp_willblock(void);
233 static void tcp_cleartaocache (void);
234 static void tcp_notify (struct inpcb *, int);
236 struct tcp_stats tcpstats_percpu[MAXCPU];
237 #ifdef SMP
238 static int
239 sysctl_tcpstats(SYSCTL_HANDLER_ARGS)
241 int cpu, error = 0;
243 for (cpu = 0; cpu < ncpus; ++cpu) {
244 if ((error = SYSCTL_OUT(req, &tcpstats_percpu[cpu],
245 sizeof(struct tcp_stats))))
246 break;
247 if ((error = SYSCTL_IN(req, &tcpstats_percpu[cpu],
248 sizeof(struct tcp_stats))))
249 break;
252 return (error);
254 SYSCTL_PROC(_net_inet_tcp, TCPCTL_STATS, stats, (CTLTYPE_OPAQUE | CTLFLAG_RW),
255 0, 0, sysctl_tcpstats, "S,tcp_stats", "TCP statistics");
256 #else
257 SYSCTL_STRUCT(_net_inet_tcp, TCPCTL_STATS, stats, CTLFLAG_RW,
258 &tcpstat, tcp_stats, "TCP statistics");
259 #endif
262 * Target size of TCP PCB hash tables. Must be a power of two.
264 * Note that this can be overridden by the kernel environment
265 * variable net.inet.tcp.tcbhashsize
267 #ifndef TCBHASHSIZE
268 #define TCBHASHSIZE 512
269 #endif
272 * This is the actual shape of what we allocate using the zone
273 * allocator. Doing it this way allows us to protect both structures
274 * using the same generation count, and also eliminates the overhead
275 * of allocating tcpcbs separately. By hiding the structure here,
276 * we avoid changing most of the rest of the code (although it needs
277 * to be changed, eventually, for greater efficiency).
279 #define ALIGNMENT 32
280 #define ALIGNM1 (ALIGNMENT - 1)
281 struct inp_tp {
282 union {
283 struct inpcb inp;
284 char align[(sizeof(struct inpcb) + ALIGNM1) & ~ALIGNM1];
285 } inp_tp_u;
286 struct tcpcb tcb;
287 struct callout inp_tp_rexmt, inp_tp_persist, inp_tp_keep, inp_tp_2msl;
288 struct callout inp_tp_delack;
290 #undef ALIGNMENT
291 #undef ALIGNM1
294 * Tcp initialization
296 void
297 tcp_init(void)
299 struct inpcbporthead *porthashbase;
300 u_long porthashmask;
301 struct vm_zone *ipi_zone;
302 int hashsize = TCBHASHSIZE;
303 int cpu;
306 * note: tcptemp is used for keepalives, and it is ok for an
307 * allocation to fail so do not specify MPF_INT.
309 mpipe_init(&tcptemp_mpipe, M_TCPTEMP, sizeof(struct tcptemp),
310 25, -1, 0, NULL);
312 tcp_ccgen = 1;
313 tcp_cleartaocache();
315 tcp_delacktime = TCPTV_DELACK;
316 tcp_keepinit = TCPTV_KEEP_INIT;
317 tcp_keepidle = TCPTV_KEEP_IDLE;
318 tcp_keepintvl = TCPTV_KEEPINTVL;
319 tcp_maxpersistidle = TCPTV_KEEP_IDLE;
320 tcp_msl = TCPTV_MSL;
321 tcp_rexmit_min = TCPTV_MIN;
322 tcp_rexmit_slop = TCPTV_CPU_VAR;
324 TUNABLE_INT_FETCH("net.inet.tcp.tcbhashsize", &hashsize);
325 if (!powerof2(hashsize)) {
326 kprintf("WARNING: TCB hash size not a power of 2\n");
327 hashsize = 512; /* safe default */
329 tcp_tcbhashsize = hashsize;
330 porthashbase = hashinit(hashsize, M_PCB, &porthashmask);
331 ipi_zone = zinit("tcpcb", sizeof(struct inp_tp), maxsockets,
332 ZONE_INTERRUPT, 0);
334 for (cpu = 0; cpu < ncpus2; cpu++) {
335 in_pcbinfo_init(&tcbinfo[cpu]);
336 tcbinfo[cpu].cpu = cpu;
337 tcbinfo[cpu].hashbase = hashinit(hashsize, M_PCB,
338 &tcbinfo[cpu].hashmask);
339 tcbinfo[cpu].porthashbase = porthashbase;
340 tcbinfo[cpu].porthashmask = porthashmask;
341 tcbinfo[cpu].wildcardhashbase = hashinit(hashsize, M_PCB,
342 &tcbinfo[cpu].wildcardhashmask);
343 tcbinfo[cpu].ipi_zone = ipi_zone;
344 TAILQ_INIT(&tcpcbackq[cpu]);
347 tcp_reass_maxseg = nmbclusters / 16;
348 TUNABLE_INT_FETCH("net.inet.tcp.reass.maxsegments", &tcp_reass_maxseg);
350 #ifdef INET6
351 #define TCP_MINPROTOHDR (sizeof(struct ip6_hdr) + sizeof(struct tcphdr))
352 #else
353 #define TCP_MINPROTOHDR (sizeof(struct tcpiphdr))
354 #endif
355 if (max_protohdr < TCP_MINPROTOHDR)
356 max_protohdr = TCP_MINPROTOHDR;
357 if (max_linkhdr + TCP_MINPROTOHDR > MHLEN)
358 panic("tcp_init");
359 #undef TCP_MINPROTOHDR
362 * Initialize TCP statistics counters for each CPU.
364 #ifdef SMP
365 for (cpu = 0; cpu < ncpus; ++cpu) {
366 bzero(&tcpstats_percpu[cpu], sizeof(struct tcp_stats));
368 #else
369 bzero(&tcpstat, sizeof(struct tcp_stats));
370 #endif
372 syncache_init();
373 tcp_sack_init();
374 tcp_thread_init();
377 void
378 tcpmsg_service_loop(void *dummy)
380 struct netmsg *msg;
382 while ((msg = lwkt_waitport(&curthread->td_msgport, 0))) {
383 do {
384 logtcp(rxmsg);
385 msg->nm_dispatch(msg);
386 } while ((msg = lwkt_getport(&curthread->td_msgport)) != NULL);
387 logtcp(delayed);
388 tcp_willblock();
389 logtcp(wait);
393 static void
394 tcp_willblock(void)
396 struct tcpcb *tp;
397 int cpu = mycpu->gd_cpuid;
399 while ((tp = TAILQ_FIRST(&tcpcbackq[cpu])) != NULL) {
400 KKASSERT(tp->t_flags & TF_ONOUTPUTQ);
401 tp->t_flags &= ~TF_ONOUTPUTQ;
402 TAILQ_REMOVE(&tcpcbackq[cpu], tp, t_outputq);
403 tcp_output(tp);
409 * Fill in the IP and TCP headers for an outgoing packet, given the tcpcb.
410 * tcp_template used to store this data in mbufs, but we now recopy it out
411 * of the tcpcb each time to conserve mbufs.
413 void
414 tcp_fillheaders(struct tcpcb *tp, void *ip_ptr, void *tcp_ptr)
416 struct inpcb *inp = tp->t_inpcb;
417 struct tcphdr *tcp_hdr = (struct tcphdr *)tcp_ptr;
419 #ifdef INET6
420 if (inp->inp_vflag & INP_IPV6) {
421 struct ip6_hdr *ip6;
423 ip6 = (struct ip6_hdr *)ip_ptr;
424 ip6->ip6_flow = (ip6->ip6_flow & ~IPV6_FLOWINFO_MASK) |
425 (inp->in6p_flowinfo & IPV6_FLOWINFO_MASK);
426 ip6->ip6_vfc = (ip6->ip6_vfc & ~IPV6_VERSION_MASK) |
427 (IPV6_VERSION & IPV6_VERSION_MASK);
428 ip6->ip6_nxt = IPPROTO_TCP;
429 ip6->ip6_plen = sizeof(struct tcphdr);
430 ip6->ip6_src = inp->in6p_laddr;
431 ip6->ip6_dst = inp->in6p_faddr;
432 tcp_hdr->th_sum = 0;
433 } else
434 #endif
436 struct ip *ip = (struct ip *) ip_ptr;
438 ip->ip_vhl = IP_VHL_BORING;
439 ip->ip_tos = 0;
440 ip->ip_len = 0;
441 ip->ip_id = 0;
442 ip->ip_off = 0;
443 ip->ip_ttl = 0;
444 ip->ip_sum = 0;
445 ip->ip_p = IPPROTO_TCP;
446 ip->ip_src = inp->inp_laddr;
447 ip->ip_dst = inp->inp_faddr;
448 tcp_hdr->th_sum = in_pseudo(ip->ip_src.s_addr,
449 ip->ip_dst.s_addr,
450 htons(sizeof(struct tcphdr) + IPPROTO_TCP));
453 tcp_hdr->th_sport = inp->inp_lport;
454 tcp_hdr->th_dport = inp->inp_fport;
455 tcp_hdr->th_seq = 0;
456 tcp_hdr->th_ack = 0;
457 tcp_hdr->th_x2 = 0;
458 tcp_hdr->th_off = 5;
459 tcp_hdr->th_flags = 0;
460 tcp_hdr->th_win = 0;
461 tcp_hdr->th_urp = 0;
465 * Create template to be used to send tcp packets on a connection.
466 * Allocates an mbuf and fills in a skeletal tcp/ip header. The only
467 * use for this function is in keepalives, which use tcp_respond.
469 struct tcptemp *
470 tcp_maketemplate(struct tcpcb *tp)
472 struct tcptemp *tmp;
474 if ((tmp = mpipe_alloc_nowait(&tcptemp_mpipe)) == NULL)
475 return (NULL);
476 tcp_fillheaders(tp, &tmp->tt_ipgen, &tmp->tt_t);
477 return (tmp);
480 void
481 tcp_freetemplate(struct tcptemp *tmp)
483 mpipe_free(&tcptemp_mpipe, tmp);
487 * Send a single message to the TCP at address specified by
488 * the given TCP/IP header. If m == NULL, then we make a copy
489 * of the tcpiphdr at ti and send directly to the addressed host.
490 * This is used to force keep alive messages out using the TCP
491 * template for a connection. If flags are given then we send
492 * a message back to the TCP which originated the * segment ti,
493 * and discard the mbuf containing it and any other attached mbufs.
495 * In any case the ack and sequence number of the transmitted
496 * segment are as specified by the parameters.
498 * NOTE: If m != NULL, then ti must point to *inside* the mbuf.
500 void
501 tcp_respond(struct tcpcb *tp, void *ipgen, struct tcphdr *th, struct mbuf *m,
502 tcp_seq ack, tcp_seq seq, int flags)
504 int tlen;
505 int win = 0;
506 struct route *ro = NULL;
507 struct route sro;
508 struct ip *ip = ipgen;
509 struct tcphdr *nth;
510 int ipflags = 0;
511 struct route_in6 *ro6 = NULL;
512 struct route_in6 sro6;
513 struct ip6_hdr *ip6 = ipgen;
514 #ifdef INET6
515 boolean_t isipv6 = (IP_VHL_V(ip->ip_vhl) == 6);
516 #else
517 const boolean_t isipv6 = FALSE;
518 #endif
520 if (tp != NULL) {
521 if (!(flags & TH_RST)) {
522 win = ssb_space(&tp->t_inpcb->inp_socket->so_rcv);
523 if (win > (long)TCP_MAXWIN << tp->rcv_scale)
524 win = (long)TCP_MAXWIN << tp->rcv_scale;
526 if (isipv6)
527 ro6 = &tp->t_inpcb->in6p_route;
528 else
529 ro = &tp->t_inpcb->inp_route;
530 } else {
531 if (isipv6) {
532 ro6 = &sro6;
533 bzero(ro6, sizeof *ro6);
534 } else {
535 ro = &sro;
536 bzero(ro, sizeof *ro);
539 if (m == NULL) {
540 m = m_gethdr(MB_DONTWAIT, MT_HEADER);
541 if (m == NULL)
542 return;
543 tlen = 0;
544 m->m_data += max_linkhdr;
545 if (isipv6) {
546 bcopy(ip6, mtod(m, caddr_t), sizeof(struct ip6_hdr));
547 ip6 = mtod(m, struct ip6_hdr *);
548 nth = (struct tcphdr *)(ip6 + 1);
549 } else {
550 bcopy(ip, mtod(m, caddr_t), sizeof(struct ip));
551 ip = mtod(m, struct ip *);
552 nth = (struct tcphdr *)(ip + 1);
554 bcopy(th, nth, sizeof(struct tcphdr));
555 flags = TH_ACK;
556 } else {
557 m_freem(m->m_next);
558 m->m_next = NULL;
559 m->m_data = (caddr_t)ipgen;
560 /* m_len is set later */
561 tlen = 0;
562 #define xchg(a, b, type) { type t; t = a; a = b; b = t; }
563 if (isipv6) {
564 xchg(ip6->ip6_dst, ip6->ip6_src, struct in6_addr);
565 nth = (struct tcphdr *)(ip6 + 1);
566 } else {
567 xchg(ip->ip_dst.s_addr, ip->ip_src.s_addr, n_long);
568 nth = (struct tcphdr *)(ip + 1);
570 if (th != nth) {
572 * this is usually a case when an extension header
573 * exists between the IPv6 header and the
574 * TCP header.
576 nth->th_sport = th->th_sport;
577 nth->th_dport = th->th_dport;
579 xchg(nth->th_dport, nth->th_sport, n_short);
580 #undef xchg
582 if (isipv6) {
583 ip6->ip6_flow = 0;
584 ip6->ip6_vfc = IPV6_VERSION;
585 ip6->ip6_nxt = IPPROTO_TCP;
586 ip6->ip6_plen = htons((u_short)(sizeof(struct tcphdr) + tlen));
587 tlen += sizeof(struct ip6_hdr) + sizeof(struct tcphdr);
588 } else {
589 tlen += sizeof(struct tcpiphdr);
590 ip->ip_len = tlen;
591 ip->ip_ttl = ip_defttl;
593 m->m_len = tlen;
594 m->m_pkthdr.len = tlen;
595 m->m_pkthdr.rcvif = (struct ifnet *) NULL;
596 nth->th_seq = htonl(seq);
597 nth->th_ack = htonl(ack);
598 nth->th_x2 = 0;
599 nth->th_off = sizeof(struct tcphdr) >> 2;
600 nth->th_flags = flags;
601 if (tp != NULL)
602 nth->th_win = htons((u_short) (win >> tp->rcv_scale));
603 else
604 nth->th_win = htons((u_short)win);
605 nth->th_urp = 0;
606 if (isipv6) {
607 nth->th_sum = 0;
608 nth->th_sum = in6_cksum(m, IPPROTO_TCP,
609 sizeof(struct ip6_hdr),
610 tlen - sizeof(struct ip6_hdr));
611 ip6->ip6_hlim = in6_selecthlim(tp ? tp->t_inpcb : NULL,
612 (ro6 && ro6->ro_rt) ?
613 ro6->ro_rt->rt_ifp : NULL);
614 } else {
615 nth->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr,
616 htons((u_short)(tlen - sizeof(struct ip) + ip->ip_p)));
617 m->m_pkthdr.csum_flags = CSUM_TCP;
618 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum);
620 #ifdef TCPDEBUG
621 if (tp == NULL || (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
622 tcp_trace(TA_OUTPUT, 0, tp, mtod(m, void *), th, 0);
623 #endif
624 if (isipv6) {
625 ip6_output(m, NULL, ro6, ipflags, NULL, NULL,
626 tp ? tp->t_inpcb : NULL);
627 if ((ro6 == &sro6) && (ro6->ro_rt != NULL)) {
628 RTFREE(ro6->ro_rt);
629 ro6->ro_rt = NULL;
631 } else {
632 ip_output(m, NULL, ro, ipflags, NULL, tp ? tp->t_inpcb : NULL);
633 if ((ro == &sro) && (ro->ro_rt != NULL)) {
634 RTFREE(ro->ro_rt);
635 ro->ro_rt = NULL;
641 * Create a new TCP control block, making an
642 * empty reassembly queue and hooking it to the argument
643 * protocol control block. The `inp' parameter must have
644 * come from the zone allocator set up in tcp_init().
646 struct tcpcb *
647 tcp_newtcpcb(struct inpcb *inp)
649 struct inp_tp *it;
650 struct tcpcb *tp;
651 #ifdef INET6
652 boolean_t isipv6 = ((inp->inp_vflag & INP_IPV6) != 0);
653 #else
654 const boolean_t isipv6 = FALSE;
655 #endif
657 it = (struct inp_tp *)inp;
658 tp = &it->tcb;
659 bzero(tp, sizeof(struct tcpcb));
660 LIST_INIT(&tp->t_segq);
661 tp->t_maxseg = tp->t_maxopd = isipv6 ? tcp_v6mssdflt : tcp_mssdflt;
663 /* Set up our timeouts. */
664 callout_init(tp->tt_rexmt = &it->inp_tp_rexmt);
665 callout_init(tp->tt_persist = &it->inp_tp_persist);
666 callout_init(tp->tt_keep = &it->inp_tp_keep);
667 callout_init(tp->tt_2msl = &it->inp_tp_2msl);
668 callout_init(tp->tt_delack = &it->inp_tp_delack);
670 if (tcp_do_rfc1323)
671 tp->t_flags = (TF_REQ_SCALE | TF_REQ_TSTMP);
672 if (tcp_do_rfc1644)
673 tp->t_flags |= TF_REQ_CC;
674 tp->t_inpcb = inp; /* XXX */
675 tp->t_state = TCPS_CLOSED;
677 * Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no
678 * rtt estimate. Set rttvar so that srtt + 4 * rttvar gives
679 * reasonable initial retransmit time.
681 tp->t_srtt = TCPTV_SRTTBASE;
682 tp->t_rttvar =
683 ((TCPTV_RTOBASE - TCPTV_SRTTBASE) << TCP_RTTVAR_SHIFT) / 4;
684 tp->t_rttmin = tcp_rexmit_min;
685 tp->t_rxtcur = TCPTV_RTOBASE;
686 tp->snd_cwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT;
687 tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT;
688 tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT;
689 tp->t_rcvtime = ticks;
691 * IPv4 TTL initialization is necessary for an IPv6 socket as well,
692 * because the socket may be bound to an IPv6 wildcard address,
693 * which may match an IPv4-mapped IPv6 address.
695 inp->inp_ip_ttl = ip_defttl;
696 inp->inp_ppcb = tp;
697 tcp_sack_tcpcb_init(tp);
698 return (tp); /* XXX */
702 * Drop a TCP connection, reporting the specified error.
703 * If connection is synchronized, then send a RST to peer.
705 struct tcpcb *
706 tcp_drop(struct tcpcb *tp, int error)
708 struct socket *so = tp->t_inpcb->inp_socket;
710 if (TCPS_HAVERCVDSYN(tp->t_state)) {
711 tp->t_state = TCPS_CLOSED;
712 tcp_output(tp);
713 tcpstat.tcps_drops++;
714 } else
715 tcpstat.tcps_conndrops++;
716 if (error == ETIMEDOUT && tp->t_softerror)
717 error = tp->t_softerror;
718 so->so_error = error;
719 return (tcp_close(tp));
722 #ifdef SMP
724 struct netmsg_remwildcard {
725 struct netmsg nm_netmsg;
726 struct inpcb *nm_inp;
727 struct inpcbinfo *nm_pcbinfo;
728 #if defined(INET6)
729 int nm_isinet6;
730 #else
731 int nm_unused01;
732 #endif
736 * Wildcard inpcb's on SMP boxes must be removed from all cpus before the
737 * inp can be detached. We do this by cycling through the cpus, ending up
738 * on the cpu controlling the inp last and then doing the disconnect.
740 static void
741 in_pcbremwildcardhash_handler(struct netmsg *msg0)
743 struct netmsg_remwildcard *msg = (struct netmsg_remwildcard *)msg0;
744 int cpu;
746 cpu = msg->nm_pcbinfo->cpu;
748 if (cpu == msg->nm_inp->inp_pcbinfo->cpu) {
749 /* note: detach removes any wildcard hash entry */
750 #ifdef INET6
751 if (msg->nm_isinet6)
752 in6_pcbdetach(msg->nm_inp);
753 else
754 #endif
755 in_pcbdetach(msg->nm_inp);
756 lwkt_replymsg(&msg->nm_netmsg.nm_lmsg, 0);
757 } else {
758 in_pcbremwildcardhash_oncpu(msg->nm_inp, msg->nm_pcbinfo);
759 cpu = (cpu + 1) % ncpus2;
760 msg->nm_pcbinfo = &tcbinfo[cpu];
761 lwkt_forwardmsg(tcp_cport(cpu), &msg->nm_netmsg.nm_lmsg);
765 #endif
768 * Close a TCP control block:
769 * discard all space held by the tcp
770 * discard internet protocol block
771 * wake up any sleepers
773 struct tcpcb *
774 tcp_close(struct tcpcb *tp)
776 struct tseg_qent *q;
777 struct inpcb *inp = tp->t_inpcb;
778 struct socket *so = inp->inp_socket;
779 struct rtentry *rt;
780 boolean_t dosavessthresh;
781 #ifdef SMP
782 int cpu;
783 #endif
784 #ifdef INET6
785 boolean_t isipv6 = ((inp->inp_vflag & INP_IPV6) != 0);
786 boolean_t isafinet6 = (INP_CHECK_SOCKAF(so, AF_INET6) != 0);
787 #else
788 const boolean_t isipv6 = FALSE;
789 #endif
792 * The tp is not instantly destroyed in the wildcard case. Setting
793 * the state to TCPS_TERMINATING will prevent the TCP stack from
794 * messing with it, though it should be noted that this change may
795 * not take effect on other cpus until we have chained the wildcard
796 * hash removal.
798 * XXX we currently depend on the BGL to synchronize the tp->t_state
799 * update and prevent other tcp protocol threads from accepting new
800 * connections on the listen socket we might be trying to close down.
802 KKASSERT(tp->t_state != TCPS_TERMINATING);
803 tp->t_state = TCPS_TERMINATING;
806 * Make sure that all of our timers are stopped before we
807 * delete the PCB.
809 callout_stop(tp->tt_rexmt);
810 callout_stop(tp->tt_persist);
811 callout_stop(tp->tt_keep);
812 callout_stop(tp->tt_2msl);
813 callout_stop(tp->tt_delack);
815 if (tp->t_flags & TF_ONOUTPUTQ) {
816 KKASSERT(tp->tt_cpu == mycpu->gd_cpuid);
817 TAILQ_REMOVE(&tcpcbackq[tp->tt_cpu], tp, t_outputq);
818 tp->t_flags &= ~TF_ONOUTPUTQ;
822 * If we got enough samples through the srtt filter,
823 * save the rtt and rttvar in the routing entry.
824 * 'Enough' is arbitrarily defined as the 16 samples.
825 * 16 samples is enough for the srtt filter to converge
826 * to within 5% of the correct value; fewer samples and
827 * we could save a very bogus rtt.
829 * Don't update the default route's characteristics and don't
830 * update anything that the user "locked".
832 if (tp->t_rttupdated >= 16) {
833 u_long i = 0;
835 if (isipv6) {
836 struct sockaddr_in6 *sin6;
838 if ((rt = inp->in6p_route.ro_rt) == NULL)
839 goto no_valid_rt;
840 sin6 = (struct sockaddr_in6 *)rt_key(rt);
841 if (IN6_IS_ADDR_UNSPECIFIED(&sin6->sin6_addr))
842 goto no_valid_rt;
843 } else
844 if ((rt = inp->inp_route.ro_rt) == NULL ||
845 ((struct sockaddr_in *)rt_key(rt))->
846 sin_addr.s_addr == INADDR_ANY)
847 goto no_valid_rt;
849 if (!(rt->rt_rmx.rmx_locks & RTV_RTT)) {
850 i = tp->t_srtt * (RTM_RTTUNIT / (hz * TCP_RTT_SCALE));
851 if (rt->rt_rmx.rmx_rtt && i)
853 * filter this update to half the old & half
854 * the new values, converting scale.
855 * See route.h and tcp_var.h for a
856 * description of the scaling constants.
858 rt->rt_rmx.rmx_rtt =
859 (rt->rt_rmx.rmx_rtt + i) / 2;
860 else
861 rt->rt_rmx.rmx_rtt = i;
862 tcpstat.tcps_cachedrtt++;
864 if (!(rt->rt_rmx.rmx_locks & RTV_RTTVAR)) {
865 i = tp->t_rttvar *
866 (RTM_RTTUNIT / (hz * TCP_RTTVAR_SCALE));
867 if (rt->rt_rmx.rmx_rttvar && i)
868 rt->rt_rmx.rmx_rttvar =
869 (rt->rt_rmx.rmx_rttvar + i) / 2;
870 else
871 rt->rt_rmx.rmx_rttvar = i;
872 tcpstat.tcps_cachedrttvar++;
875 * The old comment here said:
876 * update the pipelimit (ssthresh) if it has been updated
877 * already or if a pipesize was specified & the threshhold
878 * got below half the pipesize. I.e., wait for bad news
879 * before we start updating, then update on both good
880 * and bad news.
882 * But we want to save the ssthresh even if no pipesize is
883 * specified explicitly in the route, because such
884 * connections still have an implicit pipesize specified
885 * by the global tcp_sendspace. In the absence of a reliable
886 * way to calculate the pipesize, it will have to do.
888 i = tp->snd_ssthresh;
889 if (rt->rt_rmx.rmx_sendpipe != 0)
890 dosavessthresh = (i < rt->rt_rmx.rmx_sendpipe/2);
891 else
892 dosavessthresh = (i < so->so_snd.ssb_hiwat/2);
893 if (dosavessthresh ||
894 (!(rt->rt_rmx.rmx_locks & RTV_SSTHRESH) && (i != 0) &&
895 (rt->rt_rmx.rmx_ssthresh != 0))) {
897 * convert the limit from user data bytes to
898 * packets then to packet data bytes.
900 i = (i + tp->t_maxseg / 2) / tp->t_maxseg;
901 if (i < 2)
902 i = 2;
903 i *= tp->t_maxseg +
904 (isipv6 ?
905 sizeof(struct ip6_hdr) + sizeof(struct tcphdr) :
906 sizeof(struct tcpiphdr));
907 if (rt->rt_rmx.rmx_ssthresh)
908 rt->rt_rmx.rmx_ssthresh =
909 (rt->rt_rmx.rmx_ssthresh + i) / 2;
910 else
911 rt->rt_rmx.rmx_ssthresh = i;
912 tcpstat.tcps_cachedssthresh++;
916 no_valid_rt:
917 /* free the reassembly queue, if any */
918 while((q = LIST_FIRST(&tp->t_segq)) != NULL) {
919 LIST_REMOVE(q, tqe_q);
920 m_freem(q->tqe_m);
921 FREE(q, M_TSEGQ);
922 tcp_reass_qsize--;
924 /* throw away SACK blocks in scoreboard*/
925 if (TCP_DO_SACK(tp))
926 tcp_sack_cleanup(&tp->scb);
928 inp->inp_ppcb = NULL;
929 soisdisconnected(so);
931 * Discard the inp. In the SMP case a wildcard inp's hash (created
932 * by a listen socket or an INADDR_ANY udp socket) is replicated
933 * for each protocol thread and must be removed in the context of
934 * that thread. This is accomplished by chaining the message
935 * through the cpus.
937 * If the inp is not wildcarded we simply detach, which will remove
938 * the any hashes still present for this inp.
940 #ifdef SMP
941 if (inp->inp_flags & INP_WILDCARD_MP) {
942 struct netmsg_remwildcard *msg;
944 cpu = (inp->inp_pcbinfo->cpu + 1) % ncpus2;
945 msg = kmalloc(sizeof(struct netmsg_remwildcard),
946 M_LWKTMSG, M_INTWAIT);
947 netmsg_init(&msg->nm_netmsg, &netisr_afree_rport, 0,
948 in_pcbremwildcardhash_handler);
949 #ifdef INET6
950 msg->nm_isinet6 = isafinet6;
951 #endif
952 msg->nm_inp = inp;
953 msg->nm_pcbinfo = &tcbinfo[cpu];
954 lwkt_sendmsg(tcp_cport(cpu), &msg->nm_netmsg.nm_lmsg);
955 } else
956 #endif
958 /* note: detach removes any wildcard hash entry */
959 #ifdef INET6
960 if (isafinet6)
961 in6_pcbdetach(inp);
962 else
963 #endif
964 in_pcbdetach(inp);
966 tcpstat.tcps_closed++;
967 return (NULL);
970 static __inline void
971 tcp_drain_oncpu(struct inpcbhead *head)
973 struct inpcb *inpb;
974 struct tcpcb *tcpb;
975 struct tseg_qent *te;
977 LIST_FOREACH(inpb, head, inp_list) {
978 if (inpb->inp_flags & INP_PLACEMARKER)
979 continue;
980 if ((tcpb = intotcpcb(inpb))) {
981 while ((te = LIST_FIRST(&tcpb->t_segq)) != NULL) {
982 LIST_REMOVE(te, tqe_q);
983 m_freem(te->tqe_m);
984 FREE(te, M_TSEGQ);
985 tcp_reass_qsize--;
991 #ifdef SMP
992 struct netmsg_tcp_drain {
993 struct netmsg nm_netmsg;
994 struct inpcbhead *nm_head;
997 static void
998 tcp_drain_handler(netmsg_t netmsg)
1000 struct netmsg_tcp_drain *nm = (void *)netmsg;
1002 tcp_drain_oncpu(nm->nm_head);
1003 lwkt_replymsg(&nm->nm_netmsg.nm_lmsg, 0);
1005 #endif
1007 void
1008 tcp_drain(void)
1010 #ifdef SMP
1011 int cpu;
1012 #endif
1014 if (!do_tcpdrain)
1015 return;
1018 * Walk the tcpbs, if existing, and flush the reassembly queue,
1019 * if there is one...
1020 * XXX: The "Net/3" implementation doesn't imply that the TCP
1021 * reassembly queue should be flushed, but in a situation
1022 * where we're really low on mbufs, this is potentially
1023 * useful.
1025 #ifdef SMP
1026 for (cpu = 0; cpu < ncpus2; cpu++) {
1027 struct netmsg_tcp_drain *msg;
1029 if (cpu == mycpu->gd_cpuid) {
1030 tcp_drain_oncpu(&tcbinfo[cpu].pcblisthead);
1031 } else {
1032 msg = kmalloc(sizeof(struct netmsg_tcp_drain),
1033 M_LWKTMSG, M_NOWAIT);
1034 if (msg == NULL)
1035 continue;
1036 netmsg_init(&msg->nm_netmsg, &netisr_afree_rport, 0,
1037 tcp_drain_handler);
1038 msg->nm_head = &tcbinfo[cpu].pcblisthead;
1039 lwkt_sendmsg(tcp_cport(cpu), &msg->nm_netmsg.nm_lmsg);
1042 #else
1043 tcp_drain_oncpu(&tcbinfo[0].pcblisthead);
1044 #endif
1048 * Notify a tcp user of an asynchronous error;
1049 * store error as soft error, but wake up user
1050 * (for now, won't do anything until can select for soft error).
1052 * Do not wake up user since there currently is no mechanism for
1053 * reporting soft errors (yet - a kqueue filter may be added).
1055 static void
1056 tcp_notify(struct inpcb *inp, int error)
1058 struct tcpcb *tp = intotcpcb(inp);
1061 * Ignore some errors if we are hooked up.
1062 * If connection hasn't completed, has retransmitted several times,
1063 * and receives a second error, give up now. This is better
1064 * than waiting a long time to establish a connection that
1065 * can never complete.
1067 if (tp->t_state == TCPS_ESTABLISHED &&
1068 (error == EHOSTUNREACH || error == ENETUNREACH ||
1069 error == EHOSTDOWN)) {
1070 return;
1071 } else if (tp->t_state < TCPS_ESTABLISHED && tp->t_rxtshift > 3 &&
1072 tp->t_softerror)
1073 tcp_drop(tp, error);
1074 else
1075 tp->t_softerror = error;
1076 #if 0
1077 wakeup(&so->so_timeo);
1078 sorwakeup(so);
1079 sowwakeup(so);
1080 #endif
1083 static int
1084 tcp_pcblist(SYSCTL_HANDLER_ARGS)
1086 int error, i, n;
1087 struct inpcb *marker;
1088 struct inpcb *inp;
1089 inp_gen_t gencnt;
1090 globaldata_t gd;
1091 int origcpu, ccpu;
1093 error = 0;
1094 n = 0;
1097 * The process of preparing the TCB list is too time-consuming and
1098 * resource-intensive to repeat twice on every request.
1100 if (req->oldptr == NULL) {
1101 for (ccpu = 0; ccpu < ncpus; ++ccpu) {
1102 gd = globaldata_find(ccpu);
1103 n += tcbinfo[gd->gd_cpuid].ipi_count;
1105 req->oldidx = (n + n/8 + 10) * sizeof(struct xtcpcb);
1106 return (0);
1109 if (req->newptr != NULL)
1110 return (EPERM);
1112 marker = kmalloc(sizeof(struct inpcb), M_TEMP, M_WAITOK|M_ZERO);
1113 marker->inp_flags |= INP_PLACEMARKER;
1116 * OK, now we're committed to doing something. Run the inpcb list
1117 * for each cpu in the system and construct the output. Use a
1118 * list placemarker to deal with list changes occuring during
1119 * copyout blockages (but otherwise depend on being on the correct
1120 * cpu to avoid races).
1122 origcpu = mycpu->gd_cpuid;
1123 for (ccpu = 1; ccpu <= ncpus && error == 0; ++ccpu) {
1124 globaldata_t rgd;
1125 caddr_t inp_ppcb;
1126 struct xtcpcb xt;
1127 int cpu_id;
1129 cpu_id = (origcpu + ccpu) % ncpus;
1130 if ((smp_active_mask & (1 << cpu_id)) == 0)
1131 continue;
1132 rgd = globaldata_find(cpu_id);
1133 lwkt_setcpu_self(rgd);
1135 gencnt = tcbinfo[cpu_id].ipi_gencnt;
1136 n = tcbinfo[cpu_id].ipi_count;
1138 LIST_INSERT_HEAD(&tcbinfo[cpu_id].pcblisthead, marker, inp_list);
1139 i = 0;
1140 while ((inp = LIST_NEXT(marker, inp_list)) != NULL && i < n) {
1142 * process a snapshot of pcbs, ignoring placemarkers
1143 * and using our own to allow SYSCTL_OUT to block.
1145 LIST_REMOVE(marker, inp_list);
1146 LIST_INSERT_AFTER(inp, marker, inp_list);
1148 if (inp->inp_flags & INP_PLACEMARKER)
1149 continue;
1150 if (inp->inp_gencnt > gencnt)
1151 continue;
1152 if (prison_xinpcb(req->td, inp))
1153 continue;
1155 xt.xt_len = sizeof xt;
1156 bcopy(inp, &xt.xt_inp, sizeof *inp);
1157 inp_ppcb = inp->inp_ppcb;
1158 if (inp_ppcb != NULL)
1159 bcopy(inp_ppcb, &xt.xt_tp, sizeof xt.xt_tp);
1160 else
1161 bzero(&xt.xt_tp, sizeof xt.xt_tp);
1162 if (inp->inp_socket)
1163 sotoxsocket(inp->inp_socket, &xt.xt_socket);
1164 if ((error = SYSCTL_OUT(req, &xt, sizeof xt)) != 0)
1165 break;
1166 ++i;
1168 LIST_REMOVE(marker, inp_list);
1169 if (error == 0 && i < n) {
1170 bzero(&xt, sizeof xt);
1171 xt.xt_len = sizeof xt;
1172 while (i < n) {
1173 error = SYSCTL_OUT(req, &xt, sizeof xt);
1174 if (error)
1175 break;
1176 ++i;
1182 * Make sure we are on the same cpu we were on originally, since
1183 * higher level callers expect this. Also don't pollute caches with
1184 * migrated userland data by (eventually) returning to userland
1185 * on a different cpu.
1187 lwkt_setcpu_self(globaldata_find(origcpu));
1188 kfree(marker, M_TEMP);
1189 return (error);
1192 SYSCTL_PROC(_net_inet_tcp, TCPCTL_PCBLIST, pcblist, CTLFLAG_RD, 0, 0,
1193 tcp_pcblist, "S,xtcpcb", "List of active TCP connections");
1195 static int
1196 tcp_getcred(SYSCTL_HANDLER_ARGS)
1198 struct sockaddr_in addrs[2];
1199 struct inpcb *inp;
1200 int cpu;
1201 int error;
1203 error = suser(req->td);
1204 if (error != 0)
1205 return (error);
1206 error = SYSCTL_IN(req, addrs, sizeof addrs);
1207 if (error != 0)
1208 return (error);
1209 crit_enter();
1210 cpu = tcp_addrcpu(addrs[1].sin_addr.s_addr, addrs[1].sin_port,
1211 addrs[0].sin_addr.s_addr, addrs[0].sin_port);
1212 inp = in_pcblookup_hash(&tcbinfo[cpu], addrs[1].sin_addr,
1213 addrs[1].sin_port, addrs[0].sin_addr, addrs[0].sin_port, 0, NULL);
1214 if (inp == NULL || inp->inp_socket == NULL) {
1215 error = ENOENT;
1216 goto out;
1218 error = SYSCTL_OUT(req, inp->inp_socket->so_cred, sizeof(struct ucred));
1219 out:
1220 crit_exit();
1221 return (error);
1224 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, getcred, (CTLTYPE_OPAQUE | CTLFLAG_RW),
1225 0, 0, tcp_getcred, "S,ucred", "Get the ucred of a TCP connection");
1227 #ifdef INET6
1228 static int
1229 tcp6_getcred(SYSCTL_HANDLER_ARGS)
1231 struct sockaddr_in6 addrs[2];
1232 struct inpcb *inp;
1233 int error;
1234 boolean_t mapped = FALSE;
1236 error = suser(req->td);
1237 if (error != 0)
1238 return (error);
1239 error = SYSCTL_IN(req, addrs, sizeof addrs);
1240 if (error != 0)
1241 return (error);
1242 if (IN6_IS_ADDR_V4MAPPED(&addrs[0].sin6_addr)) {
1243 if (IN6_IS_ADDR_V4MAPPED(&addrs[1].sin6_addr))
1244 mapped = TRUE;
1245 else
1246 return (EINVAL);
1248 crit_enter();
1249 if (mapped) {
1250 inp = in_pcblookup_hash(&tcbinfo[0],
1251 *(struct in_addr *)&addrs[1].sin6_addr.s6_addr[12],
1252 addrs[1].sin6_port,
1253 *(struct in_addr *)&addrs[0].sin6_addr.s6_addr[12],
1254 addrs[0].sin6_port,
1255 0, NULL);
1256 } else {
1257 inp = in6_pcblookup_hash(&tcbinfo[0],
1258 &addrs[1].sin6_addr, addrs[1].sin6_port,
1259 &addrs[0].sin6_addr, addrs[0].sin6_port,
1260 0, NULL);
1262 if (inp == NULL || inp->inp_socket == NULL) {
1263 error = ENOENT;
1264 goto out;
1266 error = SYSCTL_OUT(req, inp->inp_socket->so_cred, sizeof(struct ucred));
1267 out:
1268 crit_exit();
1269 return (error);
1272 SYSCTL_PROC(_net_inet6_tcp6, OID_AUTO, getcred, (CTLTYPE_OPAQUE | CTLFLAG_RW),
1273 0, 0,
1274 tcp6_getcred, "S,ucred", "Get the ucred of a TCP6 connection");
1275 #endif
1277 void
1278 tcp_ctlinput(int cmd, struct sockaddr *sa, void *vip)
1280 struct ip *ip = vip;
1281 struct tcphdr *th;
1282 struct in_addr faddr;
1283 struct inpcb *inp;
1284 struct tcpcb *tp;
1285 void (*notify)(struct inpcb *, int) = tcp_notify;
1286 tcp_seq icmpseq;
1287 int arg, cpu;
1289 if ((unsigned)cmd >= PRC_NCMDS || inetctlerrmap[cmd] == 0) {
1290 return;
1293 faddr = ((struct sockaddr_in *)sa)->sin_addr;
1294 if (sa->sa_family != AF_INET || faddr.s_addr == INADDR_ANY)
1295 return;
1297 arg = inetctlerrmap[cmd];
1298 if (cmd == PRC_QUENCH) {
1299 notify = tcp_quench;
1300 } else if (icmp_may_rst &&
1301 (cmd == PRC_UNREACH_ADMIN_PROHIB ||
1302 cmd == PRC_UNREACH_PORT ||
1303 cmd == PRC_TIMXCEED_INTRANS) &&
1304 ip != NULL) {
1305 notify = tcp_drop_syn_sent;
1306 } else if (cmd == PRC_MSGSIZE) {
1307 struct icmp *icmp = (struct icmp *)
1308 ((caddr_t)ip - offsetof(struct icmp, icmp_ip));
1310 arg = ntohs(icmp->icmp_nextmtu);
1311 notify = tcp_mtudisc;
1312 } else if (PRC_IS_REDIRECT(cmd)) {
1313 ip = NULL;
1314 notify = in_rtchange;
1315 } else if (cmd == PRC_HOSTDEAD) {
1316 ip = NULL;
1319 if (ip != NULL) {
1320 crit_enter();
1321 th = (struct tcphdr *)((caddr_t)ip +
1322 (IP_VHL_HL(ip->ip_vhl) << 2));
1323 cpu = tcp_addrcpu(faddr.s_addr, th->th_dport,
1324 ip->ip_src.s_addr, th->th_sport);
1325 inp = in_pcblookup_hash(&tcbinfo[cpu], faddr, th->th_dport,
1326 ip->ip_src, th->th_sport, 0, NULL);
1327 if ((inp != NULL) && (inp->inp_socket != NULL)) {
1328 icmpseq = htonl(th->th_seq);
1329 tp = intotcpcb(inp);
1330 if (SEQ_GEQ(icmpseq, tp->snd_una) &&
1331 SEQ_LT(icmpseq, tp->snd_max))
1332 (*notify)(inp, arg);
1333 } else {
1334 struct in_conninfo inc;
1336 inc.inc_fport = th->th_dport;
1337 inc.inc_lport = th->th_sport;
1338 inc.inc_faddr = faddr;
1339 inc.inc_laddr = ip->ip_src;
1340 #ifdef INET6
1341 inc.inc_isipv6 = 0;
1342 #endif
1343 syncache_unreach(&inc, th);
1345 crit_exit();
1346 } else {
1347 for (cpu = 0; cpu < ncpus2; cpu++) {
1348 in_pcbnotifyall(&tcbinfo[cpu].pcblisthead, faddr, arg,
1349 notify);
1354 #ifdef INET6
1355 void
1356 tcp6_ctlinput(int cmd, struct sockaddr *sa, void *d)
1358 struct tcphdr th;
1359 void (*notify) (struct inpcb *, int) = tcp_notify;
1360 struct ip6_hdr *ip6;
1361 struct mbuf *m;
1362 struct ip6ctlparam *ip6cp = NULL;
1363 const struct sockaddr_in6 *sa6_src = NULL;
1364 int off;
1365 struct tcp_portonly {
1366 u_int16_t th_sport;
1367 u_int16_t th_dport;
1368 } *thp;
1369 int arg;
1371 if (sa->sa_family != AF_INET6 ||
1372 sa->sa_len != sizeof(struct sockaddr_in6))
1373 return;
1375 arg = 0;
1376 if (cmd == PRC_QUENCH)
1377 notify = tcp_quench;
1378 else if (cmd == PRC_MSGSIZE) {
1379 struct ip6ctlparam *ip6cp = d;
1380 struct icmp6_hdr *icmp6 = ip6cp->ip6c_icmp6;
1382 arg = ntohl(icmp6->icmp6_mtu);
1383 notify = tcp_mtudisc;
1384 } else if (!PRC_IS_REDIRECT(cmd) &&
1385 ((unsigned)cmd > PRC_NCMDS || inet6ctlerrmap[cmd] == 0)) {
1386 return;
1389 /* if the parameter is from icmp6, decode it. */
1390 if (d != NULL) {
1391 ip6cp = (struct ip6ctlparam *)d;
1392 m = ip6cp->ip6c_m;
1393 ip6 = ip6cp->ip6c_ip6;
1394 off = ip6cp->ip6c_off;
1395 sa6_src = ip6cp->ip6c_src;
1396 } else {
1397 m = NULL;
1398 ip6 = NULL;
1399 off = 0; /* fool gcc */
1400 sa6_src = &sa6_any;
1403 if (ip6 != NULL) {
1404 struct in_conninfo inc;
1406 * XXX: We assume that when IPV6 is non NULL,
1407 * M and OFF are valid.
1410 /* check if we can safely examine src and dst ports */
1411 if (m->m_pkthdr.len < off + sizeof *thp)
1412 return;
1414 bzero(&th, sizeof th);
1415 m_copydata(m, off, sizeof *thp, (caddr_t)&th);
1417 in6_pcbnotify(&tcbinfo[0].pcblisthead, sa, th.th_dport,
1418 (struct sockaddr *)ip6cp->ip6c_src,
1419 th.th_sport, cmd, arg, notify);
1421 inc.inc_fport = th.th_dport;
1422 inc.inc_lport = th.th_sport;
1423 inc.inc6_faddr = ((struct sockaddr_in6 *)sa)->sin6_addr;
1424 inc.inc6_laddr = ip6cp->ip6c_src->sin6_addr;
1425 inc.inc_isipv6 = 1;
1426 syncache_unreach(&inc, &th);
1427 } else
1428 in6_pcbnotify(&tcbinfo[0].pcblisthead, sa, 0,
1429 (const struct sockaddr *)sa6_src, 0, cmd, arg, notify);
1431 #endif
1434 * Following is where TCP initial sequence number generation occurs.
1436 * There are two places where we must use initial sequence numbers:
1437 * 1. In SYN-ACK packets.
1438 * 2. In SYN packets.
1440 * All ISNs for SYN-ACK packets are generated by the syncache. See
1441 * tcp_syncache.c for details.
1443 * The ISNs in SYN packets must be monotonic; TIME_WAIT recycling
1444 * depends on this property. In addition, these ISNs should be
1445 * unguessable so as to prevent connection hijacking. To satisfy
1446 * the requirements of this situation, the algorithm outlined in
1447 * RFC 1948 is used to generate sequence numbers.
1449 * Implementation details:
1451 * Time is based off the system timer, and is corrected so that it
1452 * increases by one megabyte per second. This allows for proper
1453 * recycling on high speed LANs while still leaving over an hour
1454 * before rollover.
1456 * net.inet.tcp.isn_reseed_interval controls the number of seconds
1457 * between seeding of isn_secret. This is normally set to zero,
1458 * as reseeding should not be necessary.
1462 #define ISN_BYTES_PER_SECOND 1048576
1464 u_char isn_secret[32];
1465 int isn_last_reseed;
1466 MD5_CTX isn_ctx;
1468 tcp_seq
1469 tcp_new_isn(struct tcpcb *tp)
1471 u_int32_t md5_buffer[4];
1472 tcp_seq new_isn;
1474 /* Seed if this is the first use, reseed if requested. */
1475 if ((isn_last_reseed == 0) || ((tcp_isn_reseed_interval > 0) &&
1476 (((u_int)isn_last_reseed + (u_int)tcp_isn_reseed_interval*hz)
1477 < (u_int)ticks))) {
1478 read_random_unlimited(&isn_secret, sizeof isn_secret);
1479 isn_last_reseed = ticks;
1482 /* Compute the md5 hash and return the ISN. */
1483 MD5Init(&isn_ctx);
1484 MD5Update(&isn_ctx, (u_char *)&tp->t_inpcb->inp_fport, sizeof(u_short));
1485 MD5Update(&isn_ctx, (u_char *)&tp->t_inpcb->inp_lport, sizeof(u_short));
1486 #ifdef INET6
1487 if (tp->t_inpcb->inp_vflag & INP_IPV6) {
1488 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_faddr,
1489 sizeof(struct in6_addr));
1490 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_laddr,
1491 sizeof(struct in6_addr));
1492 } else
1493 #endif
1495 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_faddr,
1496 sizeof(struct in_addr));
1497 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_laddr,
1498 sizeof(struct in_addr));
1500 MD5Update(&isn_ctx, (u_char *) &isn_secret, sizeof(isn_secret));
1501 MD5Final((u_char *) &md5_buffer, &isn_ctx);
1502 new_isn = (tcp_seq) md5_buffer[0];
1503 new_isn += ticks * (ISN_BYTES_PER_SECOND / hz);
1504 return (new_isn);
1508 * When a source quench is received, close congestion window
1509 * to one segment. We will gradually open it again as we proceed.
1511 void
1512 tcp_quench(struct inpcb *inp, int error)
1514 struct tcpcb *tp = intotcpcb(inp);
1516 if (tp != NULL) {
1517 tp->snd_cwnd = tp->t_maxseg;
1518 tp->snd_wacked = 0;
1523 * When a specific ICMP unreachable message is received and the
1524 * connection state is SYN-SENT, drop the connection. This behavior
1525 * is controlled by the icmp_may_rst sysctl.
1527 void
1528 tcp_drop_syn_sent(struct inpcb *inp, int error)
1530 struct tcpcb *tp = intotcpcb(inp);
1532 if ((tp != NULL) && (tp->t_state == TCPS_SYN_SENT))
1533 tcp_drop(tp, error);
1537 * When a `need fragmentation' ICMP is received, update our idea of the MSS
1538 * based on the new value in the route. Also nudge TCP to send something,
1539 * since we know the packet we just sent was dropped.
1540 * This duplicates some code in the tcp_mss() function in tcp_input.c.
1542 void
1543 tcp_mtudisc(struct inpcb *inp, int mtu)
1545 struct tcpcb *tp = intotcpcb(inp);
1546 struct rtentry *rt;
1547 struct socket *so = inp->inp_socket;
1548 int maxopd, mss;
1549 #ifdef INET6
1550 boolean_t isipv6 = ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0);
1551 #else
1552 const boolean_t isipv6 = FALSE;
1553 #endif
1555 if (tp == NULL)
1556 return;
1559 * If no MTU is provided in the ICMP message, use the
1560 * next lower likely value, as specified in RFC 1191.
1562 if (mtu == 0) {
1563 int oldmtu;
1565 oldmtu = tp->t_maxopd +
1566 (isipv6 ?
1567 sizeof(struct ip6_hdr) + sizeof(struct tcphdr) :
1568 sizeof(struct tcpiphdr));
1569 mtu = ip_next_mtu(oldmtu, 0);
1572 if (isipv6)
1573 rt = tcp_rtlookup6(&inp->inp_inc);
1574 else
1575 rt = tcp_rtlookup(&inp->inp_inc);
1576 if (rt != NULL) {
1577 struct rmxp_tao *taop = rmx_taop(rt->rt_rmx);
1579 if (rt->rt_rmx.rmx_mtu != 0 && rt->rt_rmx.rmx_mtu < mtu)
1580 mtu = rt->rt_rmx.rmx_mtu;
1582 maxopd = mtu -
1583 (isipv6 ?
1584 sizeof(struct ip6_hdr) + sizeof(struct tcphdr) :
1585 sizeof(struct tcpiphdr));
1588 * XXX - The following conditional probably violates the TCP
1589 * spec. The problem is that, since we don't know the
1590 * other end's MSS, we are supposed to use a conservative
1591 * default. But, if we do that, then MTU discovery will
1592 * never actually take place, because the conservative
1593 * default is much less than the MTUs typically seen
1594 * on the Internet today. For the moment, we'll sweep
1595 * this under the carpet.
1597 * The conservative default might not actually be a problem
1598 * if the only case this occurs is when sending an initial
1599 * SYN with options and data to a host we've never talked
1600 * to before. Then, they will reply with an MSS value which
1601 * will get recorded and the new parameters should get
1602 * recomputed. For Further Study.
1604 if (taop->tao_mssopt != 0 && taop->tao_mssopt < maxopd)
1605 maxopd = taop->tao_mssopt;
1606 } else
1607 maxopd = mtu -
1608 (isipv6 ?
1609 sizeof(struct ip6_hdr) + sizeof(struct tcphdr) :
1610 sizeof(struct tcpiphdr));
1612 if (tp->t_maxopd <= maxopd)
1613 return;
1614 tp->t_maxopd = maxopd;
1616 mss = maxopd;
1617 if ((tp->t_flags & (TF_REQ_TSTMP | TF_RCVD_TSTMP | TF_NOOPT)) ==
1618 (TF_REQ_TSTMP | TF_RCVD_TSTMP))
1619 mss -= TCPOLEN_TSTAMP_APPA;
1621 if ((tp->t_flags & (TF_REQ_CC | TF_RCVD_CC | TF_NOOPT)) ==
1622 (TF_REQ_CC | TF_RCVD_CC))
1623 mss -= TCPOLEN_CC_APPA;
1625 /* round down to multiple of MCLBYTES */
1626 #if (MCLBYTES & (MCLBYTES - 1)) == 0 /* test if MCLBYTES power of 2 */
1627 if (mss > MCLBYTES)
1628 mss &= ~(MCLBYTES - 1);
1629 #else
1630 if (mss > MCLBYTES)
1631 mss = (mss / MCLBYTES) * MCLBYTES;
1632 #endif
1634 if (so->so_snd.ssb_hiwat < mss)
1635 mss = so->so_snd.ssb_hiwat;
1637 tp->t_maxseg = mss;
1638 tp->t_rtttime = 0;
1639 tp->snd_nxt = tp->snd_una;
1640 tcp_output(tp);
1641 tcpstat.tcps_mturesent++;
1645 * Look-up the routing entry to the peer of this inpcb. If no route
1646 * is found and it cannot be allocated the return NULL. This routine
1647 * is called by TCP routines that access the rmx structure and by tcp_mss
1648 * to get the interface MTU.
1650 struct rtentry *
1651 tcp_rtlookup(struct in_conninfo *inc)
1653 struct route *ro = &inc->inc_route;
1655 if (ro->ro_rt == NULL || !(ro->ro_rt->rt_flags & RTF_UP)) {
1656 /* No route yet, so try to acquire one */
1657 if (inc->inc_faddr.s_addr != INADDR_ANY) {
1659 * unused portions of the structure MUST be zero'd
1660 * out because rtalloc() treats it as opaque data
1662 bzero(&ro->ro_dst, sizeof(struct sockaddr_in));
1663 ro->ro_dst.sa_family = AF_INET;
1664 ro->ro_dst.sa_len = sizeof(struct sockaddr_in);
1665 ((struct sockaddr_in *) &ro->ro_dst)->sin_addr =
1666 inc->inc_faddr;
1667 rtalloc(ro);
1670 return (ro->ro_rt);
1673 #ifdef INET6
1674 struct rtentry *
1675 tcp_rtlookup6(struct in_conninfo *inc)
1677 struct route_in6 *ro6 = &inc->inc6_route;
1679 if (ro6->ro_rt == NULL || !(ro6->ro_rt->rt_flags & RTF_UP)) {
1680 /* No route yet, so try to acquire one */
1681 if (!IN6_IS_ADDR_UNSPECIFIED(&inc->inc6_faddr)) {
1683 * unused portions of the structure MUST be zero'd
1684 * out because rtalloc() treats it as opaque data
1686 bzero(&ro6->ro_dst, sizeof(struct sockaddr_in6));
1687 ro6->ro_dst.sin6_family = AF_INET6;
1688 ro6->ro_dst.sin6_len = sizeof(struct sockaddr_in6);
1689 ro6->ro_dst.sin6_addr = inc->inc6_faddr;
1690 rtalloc((struct route *)ro6);
1693 return (ro6->ro_rt);
1695 #endif
1697 #ifdef IPSEC
1698 /* compute ESP/AH header size for TCP, including outer IP header. */
1699 size_t
1700 ipsec_hdrsiz_tcp(struct tcpcb *tp)
1702 struct inpcb *inp;
1703 struct mbuf *m;
1704 size_t hdrsiz;
1705 struct ip *ip;
1706 struct tcphdr *th;
1708 if ((tp == NULL) || ((inp = tp->t_inpcb) == NULL))
1709 return (0);
1710 MGETHDR(m, MB_DONTWAIT, MT_DATA);
1711 if (!m)
1712 return (0);
1714 #ifdef INET6
1715 if (inp->inp_vflag & INP_IPV6) {
1716 struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
1718 th = (struct tcphdr *)(ip6 + 1);
1719 m->m_pkthdr.len = m->m_len =
1720 sizeof(struct ip6_hdr) + sizeof(struct tcphdr);
1721 tcp_fillheaders(tp, ip6, th);
1722 hdrsiz = ipsec6_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp);
1723 } else
1724 #endif
1726 ip = mtod(m, struct ip *);
1727 th = (struct tcphdr *)(ip + 1);
1728 m->m_pkthdr.len = m->m_len = sizeof(struct tcpiphdr);
1729 tcp_fillheaders(tp, ip, th);
1730 hdrsiz = ipsec4_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp);
1733 m_free(m);
1734 return (hdrsiz);
1736 #endif
1739 * Return a pointer to the cached information about the remote host.
1740 * The cached information is stored in the protocol specific part of
1741 * the route metrics.
1743 struct rmxp_tao *
1744 tcp_gettaocache(struct in_conninfo *inc)
1746 struct rtentry *rt;
1748 #ifdef INET6
1749 if (inc->inc_isipv6)
1750 rt = tcp_rtlookup6(inc);
1751 else
1752 #endif
1753 rt = tcp_rtlookup(inc);
1755 /* Make sure this is a host route and is up. */
1756 if (rt == NULL ||
1757 (rt->rt_flags & (RTF_UP | RTF_HOST)) != (RTF_UP | RTF_HOST))
1758 return (NULL);
1760 return (rmx_taop(rt->rt_rmx));
1764 * Clear all the TAO cache entries, called from tcp_init.
1766 * XXX
1767 * This routine is just an empty one, because we assume that the routing
1768 * routing tables are initialized at the same time when TCP, so there is
1769 * nothing in the cache left over.
1771 static void
1772 tcp_cleartaocache(void)
1777 * TCP BANDWIDTH DELAY PRODUCT WINDOW LIMITING
1779 * This code attempts to calculate the bandwidth-delay product as a
1780 * means of determining the optimal window size to maximize bandwidth,
1781 * minimize RTT, and avoid the over-allocation of buffers on interfaces and
1782 * routers. This code also does a fairly good job keeping RTTs in check
1783 * across slow links like modems. We implement an algorithm which is very
1784 * similar (but not meant to be) TCP/Vegas. The code operates on the
1785 * transmitter side of a TCP connection and so only effects the transmit
1786 * side of the connection.
1788 * BACKGROUND: TCP makes no provision for the management of buffer space
1789 * at the end points or at the intermediate routers and switches. A TCP
1790 * stream, whether using NewReno or not, will eventually buffer as
1791 * many packets as it is able and the only reason this typically works is
1792 * due to the fairly small default buffers made available for a connection
1793 * (typicaly 16K or 32K). As machines use larger windows and/or window
1794 * scaling it is now fairly easy for even a single TCP connection to blow-out
1795 * all available buffer space not only on the local interface, but on
1796 * intermediate routers and switches as well. NewReno makes a misguided
1797 * attempt to 'solve' this problem by waiting for an actual failure to occur,
1798 * then backing off, then steadily increasing the window again until another
1799 * failure occurs, ad-infinitum. This results in terrible oscillation that
1800 * is only made worse as network loads increase and the idea of intentionally
1801 * blowing out network buffers is, frankly, a terrible way to manage network
1802 * resources.
1804 * It is far better to limit the transmit window prior to the failure
1805 * condition being achieved. There are two general ways to do this: First
1806 * you can 'scan' through different transmit window sizes and locate the
1807 * point where the RTT stops increasing, indicating that you have filled the
1808 * pipe, then scan backwards until you note that RTT stops decreasing, then
1809 * repeat ad-infinitum. This method works in principle but has severe
1810 * implementation issues due to RTT variances, timer granularity, and
1811 * instability in the algorithm which can lead to many false positives and
1812 * create oscillations as well as interact badly with other TCP streams
1813 * implementing the same algorithm.
1815 * The second method is to limit the window to the bandwidth delay product
1816 * of the link. This is the method we implement. RTT variances and our
1817 * own manipulation of the congestion window, bwnd, can potentially
1818 * destabilize the algorithm. For this reason we have to stabilize the
1819 * elements used to calculate the window. We do this by using the minimum
1820 * observed RTT, the long term average of the observed bandwidth, and
1821 * by adding two segments worth of slop. It isn't perfect but it is able
1822 * to react to changing conditions and gives us a very stable basis on
1823 * which to extend the algorithm.
1825 void
1826 tcp_xmit_bandwidth_limit(struct tcpcb *tp, tcp_seq ack_seq)
1828 u_long bw;
1829 u_long bwnd;
1830 int save_ticks;
1831 int delta_ticks;
1834 * If inflight_enable is disabled in the middle of a tcp connection,
1835 * make sure snd_bwnd is effectively disabled.
1837 if (!tcp_inflight_enable) {
1838 tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT;
1839 tp->snd_bandwidth = 0;
1840 return;
1844 * Validate the delta time. If a connection is new or has been idle
1845 * a long time we have to reset the bandwidth calculator.
1847 save_ticks = ticks;
1848 delta_ticks = save_ticks - tp->t_bw_rtttime;
1849 if (tp->t_bw_rtttime == 0 || delta_ticks < 0 || delta_ticks > hz * 10) {
1850 tp->t_bw_rtttime = ticks;
1851 tp->t_bw_rtseq = ack_seq;
1852 if (tp->snd_bandwidth == 0)
1853 tp->snd_bandwidth = tcp_inflight_min;
1854 return;
1856 if (delta_ticks == 0)
1857 return;
1860 * Sanity check, plus ignore pure window update acks.
1862 if ((int)(ack_seq - tp->t_bw_rtseq) <= 0)
1863 return;
1866 * Figure out the bandwidth. Due to the tick granularity this
1867 * is a very rough number and it MUST be averaged over a fairly
1868 * long period of time. XXX we need to take into account a link
1869 * that is not using all available bandwidth, but for now our
1870 * slop will ramp us up if this case occurs and the bandwidth later
1871 * increases.
1873 bw = (int64_t)(ack_seq - tp->t_bw_rtseq) * hz / delta_ticks;
1874 tp->t_bw_rtttime = save_ticks;
1875 tp->t_bw_rtseq = ack_seq;
1876 bw = ((int64_t)tp->snd_bandwidth * 15 + bw) >> 4;
1878 tp->snd_bandwidth = bw;
1881 * Calculate the semi-static bandwidth delay product, plus two maximal
1882 * segments. The additional slop puts us squarely in the sweet
1883 * spot and also handles the bandwidth run-up case. Without the
1884 * slop we could be locking ourselves into a lower bandwidth.
1886 * Situations Handled:
1887 * (1) Prevents over-queueing of packets on LANs, especially on
1888 * high speed LANs, allowing larger TCP buffers to be
1889 * specified, and also does a good job preventing
1890 * over-queueing of packets over choke points like modems
1891 * (at least for the transmit side).
1893 * (2) Is able to handle changing network loads (bandwidth
1894 * drops so bwnd drops, bandwidth increases so bwnd
1895 * increases).
1897 * (3) Theoretically should stabilize in the face of multiple
1898 * connections implementing the same algorithm (this may need
1899 * a little work).
1901 * (4) Stability value (defaults to 20 = 2 maximal packets) can
1902 * be adjusted with a sysctl but typically only needs to be on
1903 * very slow connections. A value no smaller then 5 should
1904 * be used, but only reduce this default if you have no other
1905 * choice.
1908 #define USERTT ((tp->t_srtt + tp->t_rttbest) / 2)
1909 bwnd = (int64_t)bw * USERTT / (hz << TCP_RTT_SHIFT) +
1910 tcp_inflight_stab * (int)tp->t_maxseg / 10;
1911 #undef USERTT
1913 if (tcp_inflight_debug > 0) {
1914 static int ltime;
1915 if ((u_int)(ticks - ltime) >= hz / tcp_inflight_debug) {
1916 ltime = ticks;
1917 kprintf("%p bw %ld rttbest %d srtt %d bwnd %ld\n",
1918 tp, bw, tp->t_rttbest, tp->t_srtt, bwnd);
1921 if ((long)bwnd < tcp_inflight_min)
1922 bwnd = tcp_inflight_min;
1923 if (bwnd > tcp_inflight_max)
1924 bwnd = tcp_inflight_max;
1925 if ((long)bwnd < tp->t_maxseg * 2)
1926 bwnd = tp->t_maxseg * 2;
1927 tp->snd_bwnd = bwnd;