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
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
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12 * notice, this list of conditions and the following disclaimer.
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15 * documentation and/or other materials provided with the distribution.
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17 * contributors may be used to endorse or promote products derived
18 * from this software without specific, prior written permission.
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39 * modification, are permitted provided that the following conditions
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63 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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 1.63 2008/11/11 10:46:58 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>
85 #include <sys/domain.h>
89 #include <sys/socket.h>
90 #include <sys/socketvar.h>
91 #include <sys/protosw.h>
92 #include <sys/random.h>
93 #include <sys/in_cksum.h>
96 #include <vm/vm_zone.h>
98 #include <net/route.h>
100 #include <net/netisr.h>
103 #include <netinet/in.h>
104 #include <netinet/in_systm.h>
105 #include <netinet/ip.h>
106 #include <netinet/ip6.h>
107 #include <netinet/in_pcb.h>
108 #include <netinet6/in6_pcb.h>
109 #include <netinet/in_var.h>
110 #include <netinet/ip_var.h>
111 #include <netinet6/ip6_var.h>
112 #include <netinet/ip_icmp.h>
114 #include <netinet/icmp6.h>
116 #include <netinet/tcp.h>
117 #include <netinet/tcp_fsm.h>
118 #include <netinet/tcp_seq.h>
119 #include <netinet/tcp_timer.h>
120 #include <netinet/tcp_timer2.h>
121 #include <netinet/tcp_var.h>
122 #include <netinet6/tcp6_var.h>
123 #include <netinet/tcpip.h>
125 #include <netinet/tcp_debug.h>
127 #include <netinet6/ip6protosw.h>
130 #include <netinet6/ipsec.h>
132 #include <netinet6/ipsec6.h>
137 #include <netproto/ipsec/ipsec.h>
139 #include <netproto/ipsec/ipsec6.h>
145 #include <sys/msgport2.h>
146 #include <machine/smp.h>
148 #include <net/netmsg2.h>
150 #if !defined(KTR_TCP)
151 #define KTR_TCP KTR_ALL
153 KTR_INFO_MASTER(tcp);
154 KTR_INFO(KTR_TCP, tcp, rxmsg, 0, "tcp getmsg", 0);
155 KTR_INFO(KTR_TCP, tcp, wait, 1, "tcp waitmsg", 0);
156 KTR_INFO(KTR_TCP, tcp, delayed, 2, "tcp execute delayed ops", 0);
157 #define logtcp(name) KTR_LOG(tcp_ ## name)
159 struct inpcbinfo tcbinfo[MAXCPU];
160 struct tcpcbackqhead tcpcbackq[MAXCPU];
162 int tcp_mpsafe_proto = 0;
163 TUNABLE_INT("net.inet.tcp.mpsafe_proto", &tcp_mpsafe_proto);
165 static int tcp_mpsafe_thread = NETMSG_SERVICE_ADAPTIVE;
166 TUNABLE_INT("net.inet.tcp.mpsafe_thread", &tcp_mpsafe_thread);
167 SYSCTL_INT(_net_inet_tcp, OID_AUTO, mpsafe_thread, CTLFLAG_RW,
168 &tcp_mpsafe_thread, 0,
169 "0:BGL, 1:Adaptive BGL, 2:No BGL(experimental)");
171 int tcp_mssdflt = TCP_MSS;
172 SYSCTL_INT(_net_inet_tcp, TCPCTL_MSSDFLT, mssdflt, CTLFLAG_RW,
173 &tcp_mssdflt, 0, "Default TCP Maximum Segment Size");
176 int tcp_v6mssdflt = TCP6_MSS;
177 SYSCTL_INT(_net_inet_tcp, TCPCTL_V6MSSDFLT, v6mssdflt, CTLFLAG_RW,
178 &tcp_v6mssdflt, 0, "Default TCP Maximum Segment Size for IPv6");
182 * Minimum MSS we accept and use. This prevents DoS attacks where
183 * we are forced to a ridiculous low MSS like 20 and send hundreds
184 * of packets instead of one. The effect scales with the available
185 * bandwidth and quickly saturates the CPU and network interface
186 * with packet generation and sending. Set to zero to disable MINMSS
187 * checking. This setting prevents us from sending too small packets.
189 int tcp_minmss = TCP_MINMSS;
190 SYSCTL_INT(_net_inet_tcp, OID_AUTO, minmss, CTLFLAG_RW,
191 &tcp_minmss , 0, "Minmum TCP Maximum Segment Size");
194 static int tcp_rttdflt = TCPTV_SRTTDFLT / PR_SLOWHZ;
195 SYSCTL_INT(_net_inet_tcp, TCPCTL_RTTDFLT, rttdflt, CTLFLAG_RW,
196 &tcp_rttdflt, 0, "Default maximum TCP Round Trip Time");
199 int tcp_do_rfc1323 = 1;
200 SYSCTL_INT(_net_inet_tcp, TCPCTL_DO_RFC1323, rfc1323, CTLFLAG_RW,
201 &tcp_do_rfc1323, 0, "Enable rfc1323 (high performance TCP) extensions");
203 int tcp_do_rfc1644 = 0;
204 SYSCTL_INT(_net_inet_tcp, TCPCTL_DO_RFC1644, rfc1644, CTLFLAG_RW,
205 &tcp_do_rfc1644, 0, "Enable rfc1644 (TTCP) extensions");
207 static int tcp_tcbhashsize = 0;
208 SYSCTL_INT(_net_inet_tcp, OID_AUTO, tcbhashsize, CTLFLAG_RD,
209 &tcp_tcbhashsize, 0, "Size of TCP control block hashtable");
211 static int do_tcpdrain = 1;
212 SYSCTL_INT(_net_inet_tcp, OID_AUTO, do_tcpdrain, CTLFLAG_RW, &do_tcpdrain, 0,
213 "Enable tcp_drain routine for extra help when low on mbufs");
216 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pcbcount, CTLFLAG_RD,
217 &tcbinfo[0].ipi_count, 0, "Number of active PCBs");
219 static int icmp_may_rst = 1;
220 SYSCTL_INT(_net_inet_tcp, OID_AUTO, icmp_may_rst, CTLFLAG_RW, &icmp_may_rst, 0,
221 "Certain ICMP unreachable messages may abort connections in SYN_SENT");
223 static int tcp_isn_reseed_interval = 0;
224 SYSCTL_INT(_net_inet_tcp, OID_AUTO, isn_reseed_interval, CTLFLAG_RW,
225 &tcp_isn_reseed_interval, 0, "Seconds between reseeding of ISN secret");
228 * TCP bandwidth limiting sysctls. Note that the default lower bound of
229 * 1024 exists only for debugging. A good production default would be
230 * something like 6100.
232 static int tcp_inflight_enable = 0;
233 SYSCTL_INT(_net_inet_tcp, OID_AUTO, inflight_enable, CTLFLAG_RW,
234 &tcp_inflight_enable, 0, "Enable automatic TCP inflight data limiting");
236 static int tcp_inflight_debug = 0;
237 SYSCTL_INT(_net_inet_tcp, OID_AUTO, inflight_debug, CTLFLAG_RW,
238 &tcp_inflight_debug, 0, "Debug TCP inflight calculations");
240 static int tcp_inflight_min = 6144;
241 SYSCTL_INT(_net_inet_tcp, OID_AUTO, inflight_min, CTLFLAG_RW,
242 &tcp_inflight_min, 0, "Lower bound for TCP inflight window");
244 static int tcp_inflight_max = TCP_MAXWIN << TCP_MAX_WINSHIFT;
245 SYSCTL_INT(_net_inet_tcp, OID_AUTO, inflight_max, CTLFLAG_RW,
246 &tcp_inflight_max, 0, "Upper bound for TCP inflight window");
248 static int tcp_inflight_stab = 20;
249 SYSCTL_INT(_net_inet_tcp, OID_AUTO, inflight_stab, CTLFLAG_RW,
250 &tcp_inflight_stab, 0, "Slop in maximal packets / 10 (20 = 2 packets)");
252 static MALLOC_DEFINE(M_TCPTEMP, "tcptemp", "TCP Templates for Keepalives");
253 static struct malloc_pipe tcptemp_mpipe;
255 static void tcp_willblock(int);
256 static void tcp_cleartaocache (void);
257 static void tcp_notify (struct inpcb *, int);
259 struct tcp_stats tcpstats_percpu[MAXCPU];
262 sysctl_tcpstats(SYSCTL_HANDLER_ARGS)
266 for (cpu = 0; cpu < ncpus; ++cpu) {
267 if ((error = SYSCTL_OUT(req, &tcpstats_percpu[cpu],
268 sizeof(struct tcp_stats))))
270 if ((error = SYSCTL_IN(req, &tcpstats_percpu[cpu],
271 sizeof(struct tcp_stats))))
277 SYSCTL_PROC(_net_inet_tcp, TCPCTL_STATS, stats, (CTLTYPE_OPAQUE | CTLFLAG_RW),
278 0, 0, sysctl_tcpstats, "S,tcp_stats", "TCP statistics");
280 SYSCTL_STRUCT(_net_inet_tcp, TCPCTL_STATS, stats, CTLFLAG_RW,
281 &tcpstat, tcp_stats, "TCP statistics");
285 * Target size of TCP PCB hash tables. Must be a power of two.
287 * Note that this can be overridden by the kernel environment
288 * variable net.inet.tcp.tcbhashsize
291 #define TCBHASHSIZE 512
295 * This is the actual shape of what we allocate using the zone
296 * allocator. Doing it this way allows us to protect both structures
297 * using the same generation count, and also eliminates the overhead
298 * of allocating tcpcbs separately. By hiding the structure here,
299 * we avoid changing most of the rest of the code (although it needs
300 * to be changed, eventually, for greater efficiency).
303 #define ALIGNM1 (ALIGNMENT - 1)
307 char align[(sizeof(struct inpcb) + ALIGNM1) & ~ALIGNM1];
310 struct tcp_callout inp_tp_rexmt;
311 struct tcp_callout inp_tp_persist;
312 struct tcp_callout inp_tp_keep;
313 struct tcp_callout inp_tp_2msl;
314 struct tcp_callout inp_tp_delack;
315 struct netmsg_tcp_timer inp_tp_timermsg;
326 struct inpcbporthead *porthashbase;
328 struct vm_zone *ipi_zone;
329 int hashsize = TCBHASHSIZE;
333 * note: tcptemp is used for keepalives, and it is ok for an
334 * allocation to fail so do not specify MPF_INT.
336 mpipe_init(&tcptemp_mpipe, M_TCPTEMP, sizeof(struct tcptemp),
342 tcp_delacktime = TCPTV_DELACK;
343 tcp_keepinit = TCPTV_KEEP_INIT;
344 tcp_keepidle = TCPTV_KEEP_IDLE;
345 tcp_keepintvl = TCPTV_KEEPINTVL;
346 tcp_maxpersistidle = TCPTV_KEEP_IDLE;
348 tcp_rexmit_min = TCPTV_MIN;
349 tcp_rexmit_slop = TCPTV_CPU_VAR;
351 TUNABLE_INT_FETCH("net.inet.tcp.tcbhashsize", &hashsize);
352 if (!powerof2(hashsize)) {
353 kprintf("WARNING: TCB hash size not a power of 2\n");
354 hashsize = 512; /* safe default */
356 tcp_tcbhashsize = hashsize;
357 porthashbase = hashinit(hashsize, M_PCB, &porthashmask);
358 ipi_zone = zinit("tcpcb", sizeof(struct inp_tp), maxsockets,
361 for (cpu = 0; cpu < ncpus2; cpu++) {
362 in_pcbinfo_init(&tcbinfo[cpu]);
363 tcbinfo[cpu].cpu = cpu;
364 tcbinfo[cpu].hashbase = hashinit(hashsize, M_PCB,
365 &tcbinfo[cpu].hashmask);
366 tcbinfo[cpu].porthashbase = porthashbase;
367 tcbinfo[cpu].porthashmask = porthashmask;
368 tcbinfo[cpu].wildcardhashbase = hashinit(hashsize, M_PCB,
369 &tcbinfo[cpu].wildcardhashmask);
370 tcbinfo[cpu].ipi_zone = ipi_zone;
371 TAILQ_INIT(&tcpcbackq[cpu]);
374 tcp_reass_maxseg = nmbclusters / 16;
375 TUNABLE_INT_FETCH("net.inet.tcp.reass.maxsegments", &tcp_reass_maxseg);
378 #define TCP_MINPROTOHDR (sizeof(struct ip6_hdr) + sizeof(struct tcphdr))
380 #define TCP_MINPROTOHDR (sizeof(struct tcpiphdr))
382 if (max_protohdr < TCP_MINPROTOHDR)
383 max_protohdr = TCP_MINPROTOHDR;
384 if (max_linkhdr + TCP_MINPROTOHDR > MHLEN)
386 #undef TCP_MINPROTOHDR
389 * Initialize TCP statistics counters for each CPU.
392 for (cpu = 0; cpu < ncpus; ++cpu) {
393 bzero(&tcpstats_percpu[cpu], sizeof(struct tcp_stats));
396 bzero(&tcpstat, sizeof(struct tcp_stats));
404 tcpmsg_service_loop(void *dummy)
410 * Thread was started with TDF_MPSAFE
414 while ((msg = lwkt_waitport(&curthread->td_msgport, 0))) {
417 mplocked = netmsg_service(msg, tcp_mpsafe_thread,
419 } while ((msg = lwkt_getport(&curthread->td_msgport)) != NULL);
422 tcp_willblock(mplocked);
428 tcp_willblock(int mplocked)
431 int cpu = mycpu->gd_cpuid;
434 if (!mplocked && !tcp_mpsafe_proto) {
435 if (TAILQ_EMPTY(&tcpcbackq[cpu]))
443 while ((tp = TAILQ_FIRST(&tcpcbackq[cpu])) != NULL) {
444 KKASSERT(tp->t_flags & TF_ONOUTPUTQ);
445 tp->t_flags &= ~TF_ONOUTPUTQ;
446 TAILQ_REMOVE(&tcpcbackq[cpu], tp, t_outputq);
456 * Fill in the IP and TCP headers for an outgoing packet, given the tcpcb.
457 * tcp_template used to store this data in mbufs, but we now recopy it out
458 * of the tcpcb each time to conserve mbufs.
461 tcp_fillheaders(struct tcpcb *tp, void *ip_ptr, void *tcp_ptr)
463 struct inpcb *inp = tp->t_inpcb;
464 struct tcphdr *tcp_hdr = (struct tcphdr *)tcp_ptr;
467 if (inp->inp_vflag & INP_IPV6) {
470 ip6 = (struct ip6_hdr *)ip_ptr;
471 ip6->ip6_flow = (ip6->ip6_flow & ~IPV6_FLOWINFO_MASK) |
472 (inp->in6p_flowinfo & IPV6_FLOWINFO_MASK);
473 ip6->ip6_vfc = (ip6->ip6_vfc & ~IPV6_VERSION_MASK) |
474 (IPV6_VERSION & IPV6_VERSION_MASK);
475 ip6->ip6_nxt = IPPROTO_TCP;
476 ip6->ip6_plen = sizeof(struct tcphdr);
477 ip6->ip6_src = inp->in6p_laddr;
478 ip6->ip6_dst = inp->in6p_faddr;
483 struct ip *ip = (struct ip *) ip_ptr;
485 ip->ip_vhl = IP_VHL_BORING;
492 ip->ip_p = IPPROTO_TCP;
493 ip->ip_src = inp->inp_laddr;
494 ip->ip_dst = inp->inp_faddr;
495 tcp_hdr->th_sum = in_pseudo(ip->ip_src.s_addr,
497 htons(sizeof(struct tcphdr) + IPPROTO_TCP));
500 tcp_hdr->th_sport = inp->inp_lport;
501 tcp_hdr->th_dport = inp->inp_fport;
506 tcp_hdr->th_flags = 0;
512 * Create template to be used to send tcp packets on a connection.
513 * Allocates an mbuf and fills in a skeletal tcp/ip header. The only
514 * use for this function is in keepalives, which use tcp_respond.
517 tcp_maketemplate(struct tcpcb *tp)
521 if ((tmp = mpipe_alloc_nowait(&tcptemp_mpipe)) == NULL)
523 tcp_fillheaders(tp, &tmp->tt_ipgen, &tmp->tt_t);
528 tcp_freetemplate(struct tcptemp *tmp)
530 mpipe_free(&tcptemp_mpipe, tmp);
534 * Send a single message to the TCP at address specified by
535 * the given TCP/IP header. If m == NULL, then we make a copy
536 * of the tcpiphdr at ti and send directly to the addressed host.
537 * This is used to force keep alive messages out using the TCP
538 * template for a connection. If flags are given then we send
539 * a message back to the TCP which originated the * segment ti,
540 * and discard the mbuf containing it and any other attached mbufs.
542 * In any case the ack and sequence number of the transmitted
543 * segment are as specified by the parameters.
545 * NOTE: If m != NULL, then ti must point to *inside* the mbuf.
548 tcp_respond(struct tcpcb *tp, void *ipgen, struct tcphdr *th, struct mbuf *m,
549 tcp_seq ack, tcp_seq seq, int flags)
553 struct route *ro = NULL;
555 struct ip *ip = ipgen;
558 struct route_in6 *ro6 = NULL;
559 struct route_in6 sro6;
560 struct ip6_hdr *ip6 = ipgen;
561 boolean_t use_tmpro = TRUE;
563 boolean_t isipv6 = (IP_VHL_V(ip->ip_vhl) == 6);
565 const boolean_t isipv6 = FALSE;
569 if (!(flags & TH_RST)) {
570 win = ssb_space(&tp->t_inpcb->inp_socket->so_rcv);
571 if (win > (long)TCP_MAXWIN << tp->rcv_scale)
572 win = (long)TCP_MAXWIN << tp->rcv_scale;
575 * Don't use the route cache of a listen socket,
576 * it is not MPSAFE; use temporary route cache.
578 if (tp->t_state != TCPS_LISTEN) {
580 ro6 = &tp->t_inpcb->in6p_route;
582 ro = &tp->t_inpcb->inp_route;
589 bzero(ro6, sizeof *ro6);
592 bzero(ro, sizeof *ro);
596 m = m_gethdr(MB_DONTWAIT, MT_HEADER);
600 m->m_data += max_linkhdr;
602 bcopy(ip6, mtod(m, caddr_t), sizeof(struct ip6_hdr));
603 ip6 = mtod(m, struct ip6_hdr *);
604 nth = (struct tcphdr *)(ip6 + 1);
606 bcopy(ip, mtod(m, caddr_t), sizeof(struct ip));
607 ip = mtod(m, struct ip *);
608 nth = (struct tcphdr *)(ip + 1);
610 bcopy(th, nth, sizeof(struct tcphdr));
615 m->m_data = (caddr_t)ipgen;
616 /* m_len is set later */
618 #define xchg(a, b, type) { type t; t = a; a = b; b = t; }
620 xchg(ip6->ip6_dst, ip6->ip6_src, struct in6_addr);
621 nth = (struct tcphdr *)(ip6 + 1);
623 xchg(ip->ip_dst.s_addr, ip->ip_src.s_addr, n_long);
624 nth = (struct tcphdr *)(ip + 1);
628 * this is usually a case when an extension header
629 * exists between the IPv6 header and the
632 nth->th_sport = th->th_sport;
633 nth->th_dport = th->th_dport;
635 xchg(nth->th_dport, nth->th_sport, n_short);
640 ip6->ip6_vfc = IPV6_VERSION;
641 ip6->ip6_nxt = IPPROTO_TCP;
642 ip6->ip6_plen = htons((u_short)(sizeof(struct tcphdr) + tlen));
643 tlen += sizeof(struct ip6_hdr) + sizeof(struct tcphdr);
645 tlen += sizeof(struct tcpiphdr);
647 ip->ip_ttl = ip_defttl;
650 m->m_pkthdr.len = tlen;
651 m->m_pkthdr.rcvif = NULL;
652 nth->th_seq = htonl(seq);
653 nth->th_ack = htonl(ack);
655 nth->th_off = sizeof(struct tcphdr) >> 2;
656 nth->th_flags = flags;
658 nth->th_win = htons((u_short) (win >> tp->rcv_scale));
660 nth->th_win = htons((u_short)win);
664 nth->th_sum = in6_cksum(m, IPPROTO_TCP,
665 sizeof(struct ip6_hdr),
666 tlen - sizeof(struct ip6_hdr));
667 ip6->ip6_hlim = in6_selecthlim(tp ? tp->t_inpcb : NULL,
668 (ro6 && ro6->ro_rt) ?
669 ro6->ro_rt->rt_ifp : NULL);
671 nth->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr,
672 htons((u_short)(tlen - sizeof(struct ip) + ip->ip_p)));
673 m->m_pkthdr.csum_flags = CSUM_TCP;
674 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum);
677 if (tp == NULL || (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
678 tcp_trace(TA_OUTPUT, 0, tp, mtod(m, void *), th, 0);
681 ip6_output(m, NULL, ro6, ipflags, NULL, NULL,
682 tp ? tp->t_inpcb : NULL);
683 if ((ro6 == &sro6) && (ro6->ro_rt != NULL)) {
688 ipflags |= IP_DEBUGROUTE;
689 ip_output(m, NULL, ro, ipflags, NULL, tp ? tp->t_inpcb : NULL);
690 if ((ro == &sro) && (ro->ro_rt != NULL)) {
698 * Create a new TCP control block, making an
699 * empty reassembly queue and hooking it to the argument
700 * protocol control block. The `inp' parameter must have
701 * come from the zone allocator set up in tcp_init().
704 tcp_newtcpcb(struct inpcb *inp)
709 boolean_t isipv6 = ((inp->inp_vflag & INP_IPV6) != 0);
711 const boolean_t isipv6 = FALSE;
714 it = (struct inp_tp *)inp;
716 bzero(tp, sizeof(struct tcpcb));
717 LIST_INIT(&tp->t_segq);
718 tp->t_maxseg = tp->t_maxopd = isipv6 ? tcp_v6mssdflt : tcp_mssdflt;
720 /* Set up our timeouts. */
721 tp->tt_rexmt = &it->inp_tp_rexmt;
722 tp->tt_persist = &it->inp_tp_persist;
723 tp->tt_keep = &it->inp_tp_keep;
724 tp->tt_2msl = &it->inp_tp_2msl;
725 tp->tt_delack = &it->inp_tp_delack;
729 * Zero out timer message. We don't create it here,
730 * since the current CPU may not be the owner of this
733 tp->tt_msg = &it->inp_tp_timermsg;
734 bzero(tp->tt_msg, sizeof(*tp->tt_msg));
737 tp->t_flags = (TF_REQ_SCALE | TF_REQ_TSTMP);
739 tp->t_flags |= TF_REQ_CC;
740 tp->t_inpcb = inp; /* XXX */
741 tp->t_state = TCPS_CLOSED;
743 * Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no
744 * rtt estimate. Set rttvar so that srtt + 4 * rttvar gives
745 * reasonable initial retransmit time.
747 tp->t_srtt = TCPTV_SRTTBASE;
749 ((TCPTV_RTOBASE - TCPTV_SRTTBASE) << TCP_RTTVAR_SHIFT) / 4;
750 tp->t_rttmin = tcp_rexmit_min;
751 tp->t_rxtcur = TCPTV_RTOBASE;
752 tp->snd_cwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT;
753 tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT;
754 tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT;
755 tp->t_rcvtime = ticks;
757 * IPv4 TTL initialization is necessary for an IPv6 socket as well,
758 * because the socket may be bound to an IPv6 wildcard address,
759 * which may match an IPv4-mapped IPv6 address.
761 inp->inp_ip_ttl = ip_defttl;
763 tcp_sack_tcpcb_init(tp);
764 return (tp); /* XXX */
768 * Drop a TCP connection, reporting the specified error.
769 * If connection is synchronized, then send a RST to peer.
772 tcp_drop(struct tcpcb *tp, int error)
774 struct socket *so = tp->t_inpcb->inp_socket;
776 if (TCPS_HAVERCVDSYN(tp->t_state)) {
777 tp->t_state = TCPS_CLOSED;
779 tcpstat.tcps_drops++;
781 tcpstat.tcps_conndrops++;
782 if (error == ETIMEDOUT && tp->t_softerror)
783 error = tp->t_softerror;
784 so->so_error = error;
785 return (tcp_close(tp));
790 struct netmsg_remwildcard {
791 struct netmsg nm_netmsg;
792 struct inpcb *nm_inp;
793 struct inpcbinfo *nm_pcbinfo;
802 * Wildcard inpcb's on SMP boxes must be removed from all cpus before the
803 * inp can be detached. We do this by cycling through the cpus, ending up
804 * on the cpu controlling the inp last and then doing the disconnect.
807 in_pcbremwildcardhash_handler(struct netmsg *msg0)
809 struct netmsg_remwildcard *msg = (struct netmsg_remwildcard *)msg0;
812 cpu = msg->nm_pcbinfo->cpu;
814 if (cpu == msg->nm_inp->inp_pcbinfo->cpu) {
815 /* note: detach removes any wildcard hash entry */
818 in6_pcbdetach(msg->nm_inp);
821 in_pcbdetach(msg->nm_inp);
822 lwkt_replymsg(&msg->nm_netmsg.nm_lmsg, 0);
824 in_pcbremwildcardhash_oncpu(msg->nm_inp, msg->nm_pcbinfo);
825 cpu = (cpu + 1) % ncpus2;
826 msg->nm_pcbinfo = &tcbinfo[cpu];
827 lwkt_forwardmsg(tcp_cport(cpu), &msg->nm_netmsg.nm_lmsg);
834 * Close a TCP control block:
835 * discard all space held by the tcp
836 * discard internet protocol block
837 * wake up any sleepers
840 tcp_close(struct tcpcb *tp)
843 struct inpcb *inp = tp->t_inpcb;
844 struct socket *so = inp->inp_socket;
846 boolean_t dosavessthresh;
851 boolean_t isipv6 = ((inp->inp_vflag & INP_IPV6) != 0);
852 boolean_t isafinet6 = (INP_CHECK_SOCKAF(so, AF_INET6) != 0);
854 const boolean_t isipv6 = FALSE;
858 * The tp is not instantly destroyed in the wildcard case. Setting
859 * the state to TCPS_TERMINATING will prevent the TCP stack from
860 * messing with it, though it should be noted that this change may
861 * not take effect on other cpus until we have chained the wildcard
864 * XXX we currently depend on the BGL to synchronize the tp->t_state
865 * update and prevent other tcp protocol threads from accepting new
866 * connections on the listen socket we might be trying to close down.
868 KKASSERT(tp->t_state != TCPS_TERMINATING);
869 tp->t_state = TCPS_TERMINATING;
872 * Make sure that all of our timers are stopped before we
873 * delete the PCB. For listen TCP socket (tp->tt_msg == NULL),
874 * timers are never used. If timer message is never created
875 * (tp->tt_msg->tt_tcb == NULL), timers are never used too.
877 if (tp->tt_msg != NULL && tp->tt_msg->tt_tcb != NULL) {
878 tcp_callout_stop(tp, tp->tt_rexmt);
879 tcp_callout_stop(tp, tp->tt_persist);
880 tcp_callout_stop(tp, tp->tt_keep);
881 tcp_callout_stop(tp, tp->tt_2msl);
882 tcp_callout_stop(tp, tp->tt_delack);
885 if (tp->t_flags & TF_ONOUTPUTQ) {
886 KKASSERT(tp->tt_cpu == mycpu->gd_cpuid);
887 TAILQ_REMOVE(&tcpcbackq[tp->tt_cpu], tp, t_outputq);
888 tp->t_flags &= ~TF_ONOUTPUTQ;
892 * If we got enough samples through the srtt filter,
893 * save the rtt and rttvar in the routing entry.
894 * 'Enough' is arbitrarily defined as the 16 samples.
895 * 16 samples is enough for the srtt filter to converge
896 * to within 5% of the correct value; fewer samples and
897 * we could save a very bogus rtt.
899 * Don't update the default route's characteristics and don't
900 * update anything that the user "locked".
902 if (tp->t_rttupdated >= 16) {
906 struct sockaddr_in6 *sin6;
908 if ((rt = inp->in6p_route.ro_rt) == NULL)
910 sin6 = (struct sockaddr_in6 *)rt_key(rt);
911 if (IN6_IS_ADDR_UNSPECIFIED(&sin6->sin6_addr))
914 if ((rt = inp->inp_route.ro_rt) == NULL ||
915 ((struct sockaddr_in *)rt_key(rt))->
916 sin_addr.s_addr == INADDR_ANY)
919 if (!(rt->rt_rmx.rmx_locks & RTV_RTT)) {
920 i = tp->t_srtt * (RTM_RTTUNIT / (hz * TCP_RTT_SCALE));
921 if (rt->rt_rmx.rmx_rtt && i)
923 * filter this update to half the old & half
924 * the new values, converting scale.
925 * See route.h and tcp_var.h for a
926 * description of the scaling constants.
929 (rt->rt_rmx.rmx_rtt + i) / 2;
931 rt->rt_rmx.rmx_rtt = i;
932 tcpstat.tcps_cachedrtt++;
934 if (!(rt->rt_rmx.rmx_locks & RTV_RTTVAR)) {
936 (RTM_RTTUNIT / (hz * TCP_RTTVAR_SCALE));
937 if (rt->rt_rmx.rmx_rttvar && i)
938 rt->rt_rmx.rmx_rttvar =
939 (rt->rt_rmx.rmx_rttvar + i) / 2;
941 rt->rt_rmx.rmx_rttvar = i;
942 tcpstat.tcps_cachedrttvar++;
945 * The old comment here said:
946 * update the pipelimit (ssthresh) if it has been updated
947 * already or if a pipesize was specified & the threshhold
948 * got below half the pipesize. I.e., wait for bad news
949 * before we start updating, then update on both good
952 * But we want to save the ssthresh even if no pipesize is
953 * specified explicitly in the route, because such
954 * connections still have an implicit pipesize specified
955 * by the global tcp_sendspace. In the absence of a reliable
956 * way to calculate the pipesize, it will have to do.
958 i = tp->snd_ssthresh;
959 if (rt->rt_rmx.rmx_sendpipe != 0)
960 dosavessthresh = (i < rt->rt_rmx.rmx_sendpipe/2);
962 dosavessthresh = (i < so->so_snd.ssb_hiwat/2);
963 if (dosavessthresh ||
964 (!(rt->rt_rmx.rmx_locks & RTV_SSTHRESH) && (i != 0) &&
965 (rt->rt_rmx.rmx_ssthresh != 0))) {
967 * convert the limit from user data bytes to
968 * packets then to packet data bytes.
970 i = (i + tp->t_maxseg / 2) / tp->t_maxseg;
975 sizeof(struct ip6_hdr) + sizeof(struct tcphdr) :
976 sizeof(struct tcpiphdr));
977 if (rt->rt_rmx.rmx_ssthresh)
978 rt->rt_rmx.rmx_ssthresh =
979 (rt->rt_rmx.rmx_ssthresh + i) / 2;
981 rt->rt_rmx.rmx_ssthresh = i;
982 tcpstat.tcps_cachedssthresh++;
987 /* free the reassembly queue, if any */
988 while((q = LIST_FIRST(&tp->t_segq)) != NULL) {
989 LIST_REMOVE(q, tqe_q);
994 /* throw away SACK blocks in scoreboard*/
996 tcp_sack_cleanup(&tp->scb);
998 inp->inp_ppcb = NULL;
999 soisdisconnected(so);
1001 tcp_destroy_timermsg(tp);
1004 * Discard the inp. In the SMP case a wildcard inp's hash (created
1005 * by a listen socket or an INADDR_ANY udp socket) is replicated
1006 * for each protocol thread and must be removed in the context of
1007 * that thread. This is accomplished by chaining the message
1010 * If the inp is not wildcarded we simply detach, which will remove
1011 * the any hashes still present for this inp.
1014 if (inp->inp_flags & INP_WILDCARD_MP) {
1015 struct netmsg_remwildcard *msg;
1017 cpu = (inp->inp_pcbinfo->cpu + 1) % ncpus2;
1018 msg = kmalloc(sizeof(struct netmsg_remwildcard),
1019 M_LWKTMSG, M_INTWAIT);
1020 netmsg_init(&msg->nm_netmsg, &netisr_afree_rport, 0,
1021 in_pcbremwildcardhash_handler);
1023 msg->nm_isinet6 = isafinet6;
1026 msg->nm_pcbinfo = &tcbinfo[cpu];
1027 lwkt_sendmsg(tcp_cport(cpu), &msg->nm_netmsg.nm_lmsg);
1031 /* note: detach removes any wildcard hash entry */
1039 tcpstat.tcps_closed++;
1043 static __inline void
1044 tcp_drain_oncpu(struct inpcbhead *head)
1048 struct tseg_qent *te;
1050 LIST_FOREACH(inpb, head, inp_list) {
1051 if (inpb->inp_flags & INP_PLACEMARKER)
1053 if ((tcpb = intotcpcb(inpb))) {
1054 while ((te = LIST_FIRST(&tcpb->t_segq)) != NULL) {
1055 LIST_REMOVE(te, tqe_q);
1065 struct netmsg_tcp_drain {
1066 struct netmsg nm_netmsg;
1067 struct inpcbhead *nm_head;
1071 tcp_drain_handler(netmsg_t netmsg)
1073 struct netmsg_tcp_drain *nm = (void *)netmsg;
1075 tcp_drain_oncpu(nm->nm_head);
1076 lwkt_replymsg(&nm->nm_netmsg.nm_lmsg, 0);
1091 * Walk the tcpbs, if existing, and flush the reassembly queue,
1092 * if there is one...
1093 * XXX: The "Net/3" implementation doesn't imply that the TCP
1094 * reassembly queue should be flushed, but in a situation
1095 * where we're really low on mbufs, this is potentially
1099 for (cpu = 0; cpu < ncpus2; cpu++) {
1100 struct netmsg_tcp_drain *msg;
1102 if (cpu == mycpu->gd_cpuid) {
1103 tcp_drain_oncpu(&tcbinfo[cpu].pcblisthead);
1105 msg = kmalloc(sizeof(struct netmsg_tcp_drain),
1106 M_LWKTMSG, M_NOWAIT);
1109 netmsg_init(&msg->nm_netmsg, &netisr_afree_rport, 0,
1111 msg->nm_head = &tcbinfo[cpu].pcblisthead;
1112 lwkt_sendmsg(tcp_cport(cpu), &msg->nm_netmsg.nm_lmsg);
1116 tcp_drain_oncpu(&tcbinfo[0].pcblisthead);
1121 * Notify a tcp user of an asynchronous error;
1122 * store error as soft error, but wake up user
1123 * (for now, won't do anything until can select for soft error).
1125 * Do not wake up user since there currently is no mechanism for
1126 * reporting soft errors (yet - a kqueue filter may be added).
1129 tcp_notify(struct inpcb *inp, int error)
1131 struct tcpcb *tp = intotcpcb(inp);
1134 * Ignore some errors if we are hooked up.
1135 * If connection hasn't completed, has retransmitted several times,
1136 * and receives a second error, give up now. This is better
1137 * than waiting a long time to establish a connection that
1138 * can never complete.
1140 if (tp->t_state == TCPS_ESTABLISHED &&
1141 (error == EHOSTUNREACH || error == ENETUNREACH ||
1142 error == EHOSTDOWN)) {
1144 } else if (tp->t_state < TCPS_ESTABLISHED && tp->t_rxtshift > 3 &&
1146 tcp_drop(tp, error);
1148 tp->t_softerror = error;
1150 wakeup(&so->so_timeo);
1157 tcp_pcblist(SYSCTL_HANDLER_ARGS)
1160 struct inpcb *marker;
1170 * The process of preparing the TCB list is too time-consuming and
1171 * resource-intensive to repeat twice on every request.
1173 if (req->oldptr == NULL) {
1174 for (ccpu = 0; ccpu < ncpus; ++ccpu) {
1175 gd = globaldata_find(ccpu);
1176 n += tcbinfo[gd->gd_cpuid].ipi_count;
1178 req->oldidx = (n + n/8 + 10) * sizeof(struct xtcpcb);
1182 if (req->newptr != NULL)
1185 marker = kmalloc(sizeof(struct inpcb), M_TEMP, M_WAITOK|M_ZERO);
1186 marker->inp_flags |= INP_PLACEMARKER;
1189 * OK, now we're committed to doing something. Run the inpcb list
1190 * for each cpu in the system and construct the output. Use a
1191 * list placemarker to deal with list changes occuring during
1192 * copyout blockages (but otherwise depend on being on the correct
1193 * cpu to avoid races).
1195 origcpu = mycpu->gd_cpuid;
1196 for (ccpu = 1; ccpu <= ncpus && error == 0; ++ccpu) {
1202 cpu_id = (origcpu + ccpu) % ncpus;
1203 if ((smp_active_mask & (1 << cpu_id)) == 0)
1205 rgd = globaldata_find(cpu_id);
1206 lwkt_setcpu_self(rgd);
1208 gencnt = tcbinfo[cpu_id].ipi_gencnt;
1209 n = tcbinfo[cpu_id].ipi_count;
1211 LIST_INSERT_HEAD(&tcbinfo[cpu_id].pcblisthead, marker, inp_list);
1213 while ((inp = LIST_NEXT(marker, inp_list)) != NULL && i < n) {
1215 * process a snapshot of pcbs, ignoring placemarkers
1216 * and using our own to allow SYSCTL_OUT to block.
1218 LIST_REMOVE(marker, inp_list);
1219 LIST_INSERT_AFTER(inp, marker, inp_list);
1221 if (inp->inp_flags & INP_PLACEMARKER)
1223 if (inp->inp_gencnt > gencnt)
1225 if (prison_xinpcb(req->td, inp))
1228 xt.xt_len = sizeof xt;
1229 bcopy(inp, &xt.xt_inp, sizeof *inp);
1230 inp_ppcb = inp->inp_ppcb;
1231 if (inp_ppcb != NULL)
1232 bcopy(inp_ppcb, &xt.xt_tp, sizeof xt.xt_tp);
1234 bzero(&xt.xt_tp, sizeof xt.xt_tp);
1235 if (inp->inp_socket)
1236 sotoxsocket(inp->inp_socket, &xt.xt_socket);
1237 if ((error = SYSCTL_OUT(req, &xt, sizeof xt)) != 0)
1241 LIST_REMOVE(marker, inp_list);
1242 if (error == 0 && i < n) {
1243 bzero(&xt, sizeof xt);
1244 xt.xt_len = sizeof xt;
1246 error = SYSCTL_OUT(req, &xt, sizeof xt);
1255 * Make sure we are on the same cpu we were on originally, since
1256 * higher level callers expect this. Also don't pollute caches with
1257 * migrated userland data by (eventually) returning to userland
1258 * on a different cpu.
1260 lwkt_setcpu_self(globaldata_find(origcpu));
1261 kfree(marker, M_TEMP);
1265 SYSCTL_PROC(_net_inet_tcp, TCPCTL_PCBLIST, pcblist, CTLFLAG_RD, 0, 0,
1266 tcp_pcblist, "S,xtcpcb", "List of active TCP connections");
1269 tcp_getcred(SYSCTL_HANDLER_ARGS)
1271 struct sockaddr_in addrs[2];
1276 error = priv_check(req->td, PRIV_ROOT);
1279 error = SYSCTL_IN(req, addrs, sizeof addrs);
1283 cpu = tcp_addrcpu(addrs[1].sin_addr.s_addr, addrs[1].sin_port,
1284 addrs[0].sin_addr.s_addr, addrs[0].sin_port);
1285 inp = in_pcblookup_hash(&tcbinfo[cpu], addrs[1].sin_addr,
1286 addrs[1].sin_port, addrs[0].sin_addr, addrs[0].sin_port, 0, NULL);
1287 if (inp == NULL || inp->inp_socket == NULL) {
1291 error = SYSCTL_OUT(req, inp->inp_socket->so_cred, sizeof(struct ucred));
1297 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, getcred, (CTLTYPE_OPAQUE | CTLFLAG_RW),
1298 0, 0, tcp_getcred, "S,ucred", "Get the ucred of a TCP connection");
1302 tcp6_getcred(SYSCTL_HANDLER_ARGS)
1304 struct sockaddr_in6 addrs[2];
1307 boolean_t mapped = FALSE;
1309 error = priv_check(req->td, PRIV_ROOT);
1312 error = SYSCTL_IN(req, addrs, sizeof addrs);
1315 if (IN6_IS_ADDR_V4MAPPED(&addrs[0].sin6_addr)) {
1316 if (IN6_IS_ADDR_V4MAPPED(&addrs[1].sin6_addr))
1323 inp = in_pcblookup_hash(&tcbinfo[0],
1324 *(struct in_addr *)&addrs[1].sin6_addr.s6_addr[12],
1326 *(struct in_addr *)&addrs[0].sin6_addr.s6_addr[12],
1330 inp = in6_pcblookup_hash(&tcbinfo[0],
1331 &addrs[1].sin6_addr, addrs[1].sin6_port,
1332 &addrs[0].sin6_addr, addrs[0].sin6_port,
1335 if (inp == NULL || inp->inp_socket == NULL) {
1339 error = SYSCTL_OUT(req, inp->inp_socket->so_cred, sizeof(struct ucred));
1345 SYSCTL_PROC(_net_inet6_tcp6, OID_AUTO, getcred, (CTLTYPE_OPAQUE | CTLFLAG_RW),
1347 tcp6_getcred, "S,ucred", "Get the ucred of a TCP6 connection");
1350 struct netmsg_tcp_notify {
1351 struct netmsg nm_nmsg;
1352 void (*nm_notify)(struct inpcb *, int);
1353 struct in_addr nm_faddr;
1358 tcp_notifyall_oncpu(struct netmsg *netmsg)
1360 struct netmsg_tcp_notify *nmsg = (struct netmsg_tcp_notify *)netmsg;
1363 in_pcbnotifyall(&tcbinfo[mycpuid].pcblisthead, nmsg->nm_faddr,
1364 nmsg->nm_arg, nmsg->nm_notify);
1366 nextcpu = mycpuid + 1;
1367 if (nextcpu < ncpus2)
1368 lwkt_forwardmsg(tcp_cport(nextcpu), &netmsg->nm_lmsg);
1370 lwkt_replymsg(&netmsg->nm_lmsg, 0);
1374 tcp_ctlinput(int cmd, struct sockaddr *sa, void *vip)
1376 struct ip *ip = vip;
1378 struct in_addr faddr;
1381 void (*notify)(struct inpcb *, int) = tcp_notify;
1385 if ((unsigned)cmd >= PRC_NCMDS || inetctlerrmap[cmd] == 0) {
1389 faddr = ((struct sockaddr_in *)sa)->sin_addr;
1390 if (sa->sa_family != AF_INET || faddr.s_addr == INADDR_ANY)
1393 arg = inetctlerrmap[cmd];
1394 if (cmd == PRC_QUENCH) {
1395 notify = tcp_quench;
1396 } else if (icmp_may_rst &&
1397 (cmd == PRC_UNREACH_ADMIN_PROHIB ||
1398 cmd == PRC_UNREACH_PORT ||
1399 cmd == PRC_TIMXCEED_INTRANS) &&
1401 notify = tcp_drop_syn_sent;
1402 } else if (cmd == PRC_MSGSIZE) {
1403 struct icmp *icmp = (struct icmp *)
1404 ((caddr_t)ip - offsetof(struct icmp, icmp_ip));
1406 arg = ntohs(icmp->icmp_nextmtu);
1407 notify = tcp_mtudisc;
1408 } else if (PRC_IS_REDIRECT(cmd)) {
1410 notify = in_rtchange;
1411 } else if (cmd == PRC_HOSTDEAD) {
1417 th = (struct tcphdr *)((caddr_t)ip +
1418 (IP_VHL_HL(ip->ip_vhl) << 2));
1419 cpu = tcp_addrcpu(faddr.s_addr, th->th_dport,
1420 ip->ip_src.s_addr, th->th_sport);
1421 inp = in_pcblookup_hash(&tcbinfo[cpu], faddr, th->th_dport,
1422 ip->ip_src, th->th_sport, 0, NULL);
1423 if ((inp != NULL) && (inp->inp_socket != NULL)) {
1424 icmpseq = htonl(th->th_seq);
1425 tp = intotcpcb(inp);
1426 if (SEQ_GEQ(icmpseq, tp->snd_una) &&
1427 SEQ_LT(icmpseq, tp->snd_max))
1428 (*notify)(inp, arg);
1430 struct in_conninfo inc;
1432 inc.inc_fport = th->th_dport;
1433 inc.inc_lport = th->th_sport;
1434 inc.inc_faddr = faddr;
1435 inc.inc_laddr = ip->ip_src;
1439 syncache_unreach(&inc, th);
1443 struct netmsg_tcp_notify nmsg;
1445 KKASSERT(&curthread->td_msgport == cpu_portfn(0));
1446 netmsg_init(&nmsg.nm_nmsg, &curthread->td_msgport, 0,
1447 tcp_notifyall_oncpu);
1448 nmsg.nm_faddr = faddr;
1450 nmsg.nm_notify = notify;
1452 lwkt_domsg(tcp_cport(0), &nmsg.nm_nmsg.nm_lmsg, 0);
1458 tcp6_ctlinput(int cmd, struct sockaddr *sa, void *d)
1461 void (*notify) (struct inpcb *, int) = tcp_notify;
1462 struct ip6_hdr *ip6;
1464 struct ip6ctlparam *ip6cp = NULL;
1465 const struct sockaddr_in6 *sa6_src = NULL;
1467 struct tcp_portonly {
1473 if (sa->sa_family != AF_INET6 ||
1474 sa->sa_len != sizeof(struct sockaddr_in6))
1478 if (cmd == PRC_QUENCH)
1479 notify = tcp_quench;
1480 else if (cmd == PRC_MSGSIZE) {
1481 struct ip6ctlparam *ip6cp = d;
1482 struct icmp6_hdr *icmp6 = ip6cp->ip6c_icmp6;
1484 arg = ntohl(icmp6->icmp6_mtu);
1485 notify = tcp_mtudisc;
1486 } else if (!PRC_IS_REDIRECT(cmd) &&
1487 ((unsigned)cmd > PRC_NCMDS || inet6ctlerrmap[cmd] == 0)) {
1491 /* if the parameter is from icmp6, decode it. */
1493 ip6cp = (struct ip6ctlparam *)d;
1495 ip6 = ip6cp->ip6c_ip6;
1496 off = ip6cp->ip6c_off;
1497 sa6_src = ip6cp->ip6c_src;
1501 off = 0; /* fool gcc */
1506 struct in_conninfo inc;
1508 * XXX: We assume that when IPV6 is non NULL,
1509 * M and OFF are valid.
1512 /* check if we can safely examine src and dst ports */
1513 if (m->m_pkthdr.len < off + sizeof *thp)
1516 bzero(&th, sizeof th);
1517 m_copydata(m, off, sizeof *thp, (caddr_t)&th);
1519 in6_pcbnotify(&tcbinfo[0].pcblisthead, sa, th.th_dport,
1520 (struct sockaddr *)ip6cp->ip6c_src,
1521 th.th_sport, cmd, arg, notify);
1523 inc.inc_fport = th.th_dport;
1524 inc.inc_lport = th.th_sport;
1525 inc.inc6_faddr = ((struct sockaddr_in6 *)sa)->sin6_addr;
1526 inc.inc6_laddr = ip6cp->ip6c_src->sin6_addr;
1528 syncache_unreach(&inc, &th);
1530 in6_pcbnotify(&tcbinfo[0].pcblisthead, sa, 0,
1531 (const struct sockaddr *)sa6_src, 0, cmd, arg, notify);
1536 * Following is where TCP initial sequence number generation occurs.
1538 * There are two places where we must use initial sequence numbers:
1539 * 1. In SYN-ACK packets.
1540 * 2. In SYN packets.
1542 * All ISNs for SYN-ACK packets are generated by the syncache. See
1543 * tcp_syncache.c for details.
1545 * The ISNs in SYN packets must be monotonic; TIME_WAIT recycling
1546 * depends on this property. In addition, these ISNs should be
1547 * unguessable so as to prevent connection hijacking. To satisfy
1548 * the requirements of this situation, the algorithm outlined in
1549 * RFC 1948 is used to generate sequence numbers.
1551 * Implementation details:
1553 * Time is based off the system timer, and is corrected so that it
1554 * increases by one megabyte per second. This allows for proper
1555 * recycling on high speed LANs while still leaving over an hour
1558 * net.inet.tcp.isn_reseed_interval controls the number of seconds
1559 * between seeding of isn_secret. This is normally set to zero,
1560 * as reseeding should not be necessary.
1564 #define ISN_BYTES_PER_SECOND 1048576
1566 u_char isn_secret[32];
1567 int isn_last_reseed;
1571 tcp_new_isn(struct tcpcb *tp)
1573 u_int32_t md5_buffer[4];
1576 /* Seed if this is the first use, reseed if requested. */
1577 if ((isn_last_reseed == 0) || ((tcp_isn_reseed_interval > 0) &&
1578 (((u_int)isn_last_reseed + (u_int)tcp_isn_reseed_interval*hz)
1580 read_random_unlimited(&isn_secret, sizeof isn_secret);
1581 isn_last_reseed = ticks;
1584 /* Compute the md5 hash and return the ISN. */
1586 MD5Update(&isn_ctx, (u_char *)&tp->t_inpcb->inp_fport, sizeof(u_short));
1587 MD5Update(&isn_ctx, (u_char *)&tp->t_inpcb->inp_lport, sizeof(u_short));
1589 if (tp->t_inpcb->inp_vflag & INP_IPV6) {
1590 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_faddr,
1591 sizeof(struct in6_addr));
1592 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_laddr,
1593 sizeof(struct in6_addr));
1597 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_faddr,
1598 sizeof(struct in_addr));
1599 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_laddr,
1600 sizeof(struct in_addr));
1602 MD5Update(&isn_ctx, (u_char *) &isn_secret, sizeof(isn_secret));
1603 MD5Final((u_char *) &md5_buffer, &isn_ctx);
1604 new_isn = (tcp_seq) md5_buffer[0];
1605 new_isn += ticks * (ISN_BYTES_PER_SECOND / hz);
1610 * When a source quench is received, close congestion window
1611 * to one segment. We will gradually open it again as we proceed.
1614 tcp_quench(struct inpcb *inp, int error)
1616 struct tcpcb *tp = intotcpcb(inp);
1619 tp->snd_cwnd = tp->t_maxseg;
1625 * When a specific ICMP unreachable message is received and the
1626 * connection state is SYN-SENT, drop the connection. This behavior
1627 * is controlled by the icmp_may_rst sysctl.
1630 tcp_drop_syn_sent(struct inpcb *inp, int error)
1632 struct tcpcb *tp = intotcpcb(inp);
1634 if ((tp != NULL) && (tp->t_state == TCPS_SYN_SENT))
1635 tcp_drop(tp, error);
1639 * When a `need fragmentation' ICMP is received, update our idea of the MSS
1640 * based on the new value in the route. Also nudge TCP to send something,
1641 * since we know the packet we just sent was dropped.
1642 * This duplicates some code in the tcp_mss() function in tcp_input.c.
1645 tcp_mtudisc(struct inpcb *inp, int mtu)
1647 struct tcpcb *tp = intotcpcb(inp);
1649 struct socket *so = inp->inp_socket;
1652 boolean_t isipv6 = ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0);
1654 const boolean_t isipv6 = FALSE;
1661 * If no MTU is provided in the ICMP message, use the
1662 * next lower likely value, as specified in RFC 1191.
1667 oldmtu = tp->t_maxopd +
1669 sizeof(struct ip6_hdr) + sizeof(struct tcphdr) :
1670 sizeof(struct tcpiphdr));
1671 mtu = ip_next_mtu(oldmtu, 0);
1675 rt = tcp_rtlookup6(&inp->inp_inc);
1677 rt = tcp_rtlookup(&inp->inp_inc);
1679 struct rmxp_tao *taop = rmx_taop(rt->rt_rmx);
1681 if (rt->rt_rmx.rmx_mtu != 0 && rt->rt_rmx.rmx_mtu < mtu)
1682 mtu = rt->rt_rmx.rmx_mtu;
1686 sizeof(struct ip6_hdr) + sizeof(struct tcphdr) :
1687 sizeof(struct tcpiphdr));
1690 * XXX - The following conditional probably violates the TCP
1691 * spec. The problem is that, since we don't know the
1692 * other end's MSS, we are supposed to use a conservative
1693 * default. But, if we do that, then MTU discovery will
1694 * never actually take place, because the conservative
1695 * default is much less than the MTUs typically seen
1696 * on the Internet today. For the moment, we'll sweep
1697 * this under the carpet.
1699 * The conservative default might not actually be a problem
1700 * if the only case this occurs is when sending an initial
1701 * SYN with options and data to a host we've never talked
1702 * to before. Then, they will reply with an MSS value which
1703 * will get recorded and the new parameters should get
1704 * recomputed. For Further Study.
1706 if (taop->tao_mssopt != 0 && taop->tao_mssopt < maxopd)
1707 maxopd = taop->tao_mssopt;
1711 sizeof(struct ip6_hdr) + sizeof(struct tcphdr) :
1712 sizeof(struct tcpiphdr));
1714 if (tp->t_maxopd <= maxopd)
1716 tp->t_maxopd = maxopd;
1719 if ((tp->t_flags & (TF_REQ_TSTMP | TF_RCVD_TSTMP | TF_NOOPT)) ==
1720 (TF_REQ_TSTMP | TF_RCVD_TSTMP))
1721 mss -= TCPOLEN_TSTAMP_APPA;
1723 if ((tp->t_flags & (TF_REQ_CC | TF_RCVD_CC | TF_NOOPT)) ==
1724 (TF_REQ_CC | TF_RCVD_CC))
1725 mss -= TCPOLEN_CC_APPA;
1727 /* round down to multiple of MCLBYTES */
1728 #if (MCLBYTES & (MCLBYTES - 1)) == 0 /* test if MCLBYTES power of 2 */
1730 mss &= ~(MCLBYTES - 1);
1733 mss = (mss / MCLBYTES) * MCLBYTES;
1736 if (so->so_snd.ssb_hiwat < mss)
1737 mss = so->so_snd.ssb_hiwat;
1741 tp->snd_nxt = tp->snd_una;
1743 tcpstat.tcps_mturesent++;
1747 * Look-up the routing entry to the peer of this inpcb. If no route
1748 * is found and it cannot be allocated the return NULL. This routine
1749 * is called by TCP routines that access the rmx structure and by tcp_mss
1750 * to get the interface MTU.
1753 tcp_rtlookup(struct in_conninfo *inc)
1755 struct route *ro = &inc->inc_route;
1757 if (ro->ro_rt == NULL || !(ro->ro_rt->rt_flags & RTF_UP)) {
1758 /* No route yet, so try to acquire one */
1759 if (inc->inc_faddr.s_addr != INADDR_ANY) {
1761 * unused portions of the structure MUST be zero'd
1762 * out because rtalloc() treats it as opaque data
1764 bzero(&ro->ro_dst, sizeof(struct sockaddr_in));
1765 ro->ro_dst.sa_family = AF_INET;
1766 ro->ro_dst.sa_len = sizeof(struct sockaddr_in);
1767 ((struct sockaddr_in *) &ro->ro_dst)->sin_addr =
1777 tcp_rtlookup6(struct in_conninfo *inc)
1779 struct route_in6 *ro6 = &inc->inc6_route;
1781 if (ro6->ro_rt == NULL || !(ro6->ro_rt->rt_flags & RTF_UP)) {
1782 /* No route yet, so try to acquire one */
1783 if (!IN6_IS_ADDR_UNSPECIFIED(&inc->inc6_faddr)) {
1785 * unused portions of the structure MUST be zero'd
1786 * out because rtalloc() treats it as opaque data
1788 bzero(&ro6->ro_dst, sizeof(struct sockaddr_in6));
1789 ro6->ro_dst.sin6_family = AF_INET6;
1790 ro6->ro_dst.sin6_len = sizeof(struct sockaddr_in6);
1791 ro6->ro_dst.sin6_addr = inc->inc6_faddr;
1792 rtalloc((struct route *)ro6);
1795 return (ro6->ro_rt);
1800 /* compute ESP/AH header size for TCP, including outer IP header. */
1802 ipsec_hdrsiz_tcp(struct tcpcb *tp)
1810 if ((tp == NULL) || ((inp = tp->t_inpcb) == NULL))
1812 MGETHDR(m, MB_DONTWAIT, MT_DATA);
1817 if (inp->inp_vflag & INP_IPV6) {
1818 struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
1820 th = (struct tcphdr *)(ip6 + 1);
1821 m->m_pkthdr.len = m->m_len =
1822 sizeof(struct ip6_hdr) + sizeof(struct tcphdr);
1823 tcp_fillheaders(tp, ip6, th);
1824 hdrsiz = ipsec6_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp);
1828 ip = mtod(m, struct ip *);
1829 th = (struct tcphdr *)(ip + 1);
1830 m->m_pkthdr.len = m->m_len = sizeof(struct tcpiphdr);
1831 tcp_fillheaders(tp, ip, th);
1832 hdrsiz = ipsec4_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp);
1841 * Return a pointer to the cached information about the remote host.
1842 * The cached information is stored in the protocol specific part of
1843 * the route metrics.
1846 tcp_gettaocache(struct in_conninfo *inc)
1851 if (inc->inc_isipv6)
1852 rt = tcp_rtlookup6(inc);
1855 rt = tcp_rtlookup(inc);
1857 /* Make sure this is a host route and is up. */
1859 (rt->rt_flags & (RTF_UP | RTF_HOST)) != (RTF_UP | RTF_HOST))
1862 return (rmx_taop(rt->rt_rmx));
1866 * Clear all the TAO cache entries, called from tcp_init.
1869 * This routine is just an empty one, because we assume that the routing
1870 * routing tables are initialized at the same time when TCP, so there is
1871 * nothing in the cache left over.
1874 tcp_cleartaocache(void)
1879 * TCP BANDWIDTH DELAY PRODUCT WINDOW LIMITING
1881 * This code attempts to calculate the bandwidth-delay product as a
1882 * means of determining the optimal window size to maximize bandwidth,
1883 * minimize RTT, and avoid the over-allocation of buffers on interfaces and
1884 * routers. This code also does a fairly good job keeping RTTs in check
1885 * across slow links like modems. We implement an algorithm which is very
1886 * similar (but not meant to be) TCP/Vegas. The code operates on the
1887 * transmitter side of a TCP connection and so only effects the transmit
1888 * side of the connection.
1890 * BACKGROUND: TCP makes no provision for the management of buffer space
1891 * at the end points or at the intermediate routers and switches. A TCP
1892 * stream, whether using NewReno or not, will eventually buffer as
1893 * many packets as it is able and the only reason this typically works is
1894 * due to the fairly small default buffers made available for a connection
1895 * (typicaly 16K or 32K). As machines use larger windows and/or window
1896 * scaling it is now fairly easy for even a single TCP connection to blow-out
1897 * all available buffer space not only on the local interface, but on
1898 * intermediate routers and switches as well. NewReno makes a misguided
1899 * attempt to 'solve' this problem by waiting for an actual failure to occur,
1900 * then backing off, then steadily increasing the window again until another
1901 * failure occurs, ad-infinitum. This results in terrible oscillation that
1902 * is only made worse as network loads increase and the idea of intentionally
1903 * blowing out network buffers is, frankly, a terrible way to manage network
1906 * It is far better to limit the transmit window prior to the failure
1907 * condition being achieved. There are two general ways to do this: First
1908 * you can 'scan' through different transmit window sizes and locate the
1909 * point where the RTT stops increasing, indicating that you have filled the
1910 * pipe, then scan backwards until you note that RTT stops decreasing, then
1911 * repeat ad-infinitum. This method works in principle but has severe
1912 * implementation issues due to RTT variances, timer granularity, and
1913 * instability in the algorithm which can lead to many false positives and
1914 * create oscillations as well as interact badly with other TCP streams
1915 * implementing the same algorithm.
1917 * The second method is to limit the window to the bandwidth delay product
1918 * of the link. This is the method we implement. RTT variances and our
1919 * own manipulation of the congestion window, bwnd, can potentially
1920 * destabilize the algorithm. For this reason we have to stabilize the
1921 * elements used to calculate the window. We do this by using the minimum
1922 * observed RTT, the long term average of the observed bandwidth, and
1923 * by adding two segments worth of slop. It isn't perfect but it is able
1924 * to react to changing conditions and gives us a very stable basis on
1925 * which to extend the algorithm.
1928 tcp_xmit_bandwidth_limit(struct tcpcb *tp, tcp_seq ack_seq)
1936 * If inflight_enable is disabled in the middle of a tcp connection,
1937 * make sure snd_bwnd is effectively disabled.
1939 if (!tcp_inflight_enable) {
1940 tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT;
1941 tp->snd_bandwidth = 0;
1946 * Validate the delta time. If a connection is new or has been idle
1947 * a long time we have to reset the bandwidth calculator.
1950 delta_ticks = save_ticks - tp->t_bw_rtttime;
1951 if (tp->t_bw_rtttime == 0 || delta_ticks < 0 || delta_ticks > hz * 10) {
1952 tp->t_bw_rtttime = ticks;
1953 tp->t_bw_rtseq = ack_seq;
1954 if (tp->snd_bandwidth == 0)
1955 tp->snd_bandwidth = tcp_inflight_min;
1958 if (delta_ticks == 0)
1962 * Sanity check, plus ignore pure window update acks.
1964 if ((int)(ack_seq - tp->t_bw_rtseq) <= 0)
1968 * Figure out the bandwidth. Due to the tick granularity this
1969 * is a very rough number and it MUST be averaged over a fairly
1970 * long period of time. XXX we need to take into account a link
1971 * that is not using all available bandwidth, but for now our
1972 * slop will ramp us up if this case occurs and the bandwidth later
1975 bw = (int64_t)(ack_seq - tp->t_bw_rtseq) * hz / delta_ticks;
1976 tp->t_bw_rtttime = save_ticks;
1977 tp->t_bw_rtseq = ack_seq;
1978 bw = ((int64_t)tp->snd_bandwidth * 15 + bw) >> 4;
1980 tp->snd_bandwidth = bw;
1983 * Calculate the semi-static bandwidth delay product, plus two maximal
1984 * segments. The additional slop puts us squarely in the sweet
1985 * spot and also handles the bandwidth run-up case. Without the
1986 * slop we could be locking ourselves into a lower bandwidth.
1988 * Situations Handled:
1989 * (1) Prevents over-queueing of packets on LANs, especially on
1990 * high speed LANs, allowing larger TCP buffers to be
1991 * specified, and also does a good job preventing
1992 * over-queueing of packets over choke points like modems
1993 * (at least for the transmit side).
1995 * (2) Is able to handle changing network loads (bandwidth
1996 * drops so bwnd drops, bandwidth increases so bwnd
1999 * (3) Theoretically should stabilize in the face of multiple
2000 * connections implementing the same algorithm (this may need
2003 * (4) Stability value (defaults to 20 = 2 maximal packets) can
2004 * be adjusted with a sysctl but typically only needs to be on
2005 * very slow connections. A value no smaller then 5 should
2006 * be used, but only reduce this default if you have no other
2010 #define USERTT ((tp->t_srtt + tp->t_rttbest) / 2)
2011 bwnd = (int64_t)bw * USERTT / (hz << TCP_RTT_SHIFT) +
2012 tcp_inflight_stab * (int)tp->t_maxseg / 10;
2015 if (tcp_inflight_debug > 0) {
2017 if ((u_int)(ticks - ltime) >= hz / tcp_inflight_debug) {
2019 kprintf("%p bw %ld rttbest %d srtt %d bwnd %ld\n",
2020 tp, bw, tp->t_rttbest, tp->t_srtt, bwnd);
2023 if ((long)bwnd < tcp_inflight_min)
2024 bwnd = tcp_inflight_min;
2025 if (bwnd > tcp_inflight_max)
2026 bwnd = tcp_inflight_max;
2027 if ((long)bwnd < tp->t_maxseg * 2)
2028 bwnd = tp->t_maxseg * 2;
2029 tp->snd_bwnd = bwnd;