tcp_timewait.c revision 125819
1/* 2 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * @(#)tcp_subr.c 8.2 (Berkeley) 5/24/95 34 * $FreeBSD: head/sys/netinet/tcp_timewait.c 125819 2004-02-14 21:49:48Z bms $ 35 */ 36 37#include "opt_compat.h" 38#include "opt_inet.h" 39#include "opt_inet6.h" 40#include "opt_ipsec.h" 41#include "opt_mac.h" 42#include "opt_tcpdebug.h" 43 44#include <sys/param.h> 45#include <sys/systm.h> 46#include <sys/callout.h> 47#include <sys/kernel.h> 48#include <sys/sysctl.h> 49#include <sys/mac.h> 50#include <sys/malloc.h> 51#include <sys/mbuf.h> 52#ifdef INET6 53#include <sys/domain.h> 54#endif 55#include <sys/proc.h> 56#include <sys/socket.h> 57#include <sys/socketvar.h> 58#include <sys/protosw.h> 59#include <sys/random.h> 60 61#include <vm/uma.h> 62 63#include <net/route.h> 64#include <net/if.h> 65 66#include <netinet/in.h> 67#include <netinet/in_systm.h> 68#include <netinet/ip.h> 69#ifdef INET6 70#include <netinet/ip6.h> 71#endif 72#include <netinet/in_pcb.h> 73#ifdef INET6 74#include <netinet6/in6_pcb.h> 75#endif 76#include <netinet/in_var.h> 77#include <netinet/ip_var.h> 78#ifdef INET6 79#include <netinet6/ip6_var.h> 80#include <netinet6/nd6.h> 81#endif 82#include <netinet/tcp.h> 83#include <netinet/tcp_fsm.h> 84#include <netinet/tcp_seq.h> 85#include <netinet/tcp_timer.h> 86#include <netinet/tcp_var.h> 87#ifdef INET6 88#include <netinet6/tcp6_var.h> 89#endif 90#include <netinet/tcpip.h> 91#ifdef TCPDEBUG 92#include <netinet/tcp_debug.h> 93#endif 94#include <netinet6/ip6protosw.h> 95 96#ifdef IPSEC 97#include <netinet6/ipsec.h> 98#ifdef INET6 99#include <netinet6/ipsec6.h> 100#endif 101#endif /*IPSEC*/ 102 103#ifdef FAST_IPSEC 104#include <netipsec/ipsec.h> 105#include <netipsec/xform.h> 106#ifdef INET6 107#include <netipsec/ipsec6.h> 108#endif 109#include <netipsec/key.h> 110#define IPSEC 111#endif /*FAST_IPSEC*/ 112 113#include <machine/in_cksum.h> 114#include <sys/md5.h> 115 116int tcp_mssdflt = TCP_MSS; 117SYSCTL_INT(_net_inet_tcp, TCPCTL_MSSDFLT, mssdflt, CTLFLAG_RW, 118 &tcp_mssdflt , 0, "Default TCP Maximum Segment Size"); 119 120#ifdef INET6 121int tcp_v6mssdflt = TCP6_MSS; 122SYSCTL_INT(_net_inet_tcp, TCPCTL_V6MSSDFLT, v6mssdflt, 123 CTLFLAG_RW, &tcp_v6mssdflt , 0, 124 "Default TCP Maximum Segment Size for IPv6"); 125#endif 126 127/* 128 * Minimum MSS we accept and use. This prevents DoS attacks where 129 * we are forced to a ridiculous low MSS like 20 and send hundreds 130 * of packets instead of one. The effect scales with the available 131 * bandwidth and quickly saturates the CPU and network interface 132 * with packet generation and sending. Set to zero to disable MINMSS 133 * checking. This setting prevents us from sending too small packets. 134 */ 135int tcp_minmss = TCP_MINMSS; 136SYSCTL_INT(_net_inet_tcp, OID_AUTO, minmss, CTLFLAG_RW, 137 &tcp_minmss , 0, "Minmum TCP Maximum Segment Size"); 138/* 139 * Number of TCP segments per second we accept from remote host 140 * before we start to calculate average segment size. If average 141 * segment size drops below the minimum TCP MSS we assume a DoS 142 * attack and reset+drop the connection. Care has to be taken not to 143 * set this value too small to not kill interactive type connections 144 * (telnet, SSH) which send many small packets. 145 */ 146int tcp_minmssoverload = TCP_MINMSSOVERLOAD; 147SYSCTL_INT(_net_inet_tcp, OID_AUTO, minmssoverload, CTLFLAG_RW, 148 &tcp_minmssoverload , 0, "Number of TCP Segments per Second allowed to" 149 "be under the MINMSS Size"); 150 151#if 0 152static int tcp_rttdflt = TCPTV_SRTTDFLT / PR_SLOWHZ; 153SYSCTL_INT(_net_inet_tcp, TCPCTL_RTTDFLT, rttdflt, CTLFLAG_RW, 154 &tcp_rttdflt , 0, "Default maximum TCP Round Trip Time"); 155#endif 156 157int tcp_do_rfc1323 = 1; 158SYSCTL_INT(_net_inet_tcp, TCPCTL_DO_RFC1323, rfc1323, CTLFLAG_RW, 159 &tcp_do_rfc1323 , 0, "Enable rfc1323 (high performance TCP) extensions"); 160 161int tcp_do_rfc1644 = 0; 162SYSCTL_INT(_net_inet_tcp, TCPCTL_DO_RFC1644, rfc1644, CTLFLAG_RW, 163 &tcp_do_rfc1644 , 0, "Enable rfc1644 (TTCP) extensions"); 164 165static int tcp_tcbhashsize = 0; 166SYSCTL_INT(_net_inet_tcp, OID_AUTO, tcbhashsize, CTLFLAG_RDTUN, 167 &tcp_tcbhashsize, 0, "Size of TCP control-block hashtable"); 168 169static int do_tcpdrain = 1; 170SYSCTL_INT(_net_inet_tcp, OID_AUTO, do_tcpdrain, CTLFLAG_RW, &do_tcpdrain, 0, 171 "Enable tcp_drain routine for extra help when low on mbufs"); 172 173SYSCTL_INT(_net_inet_tcp, OID_AUTO, pcbcount, CTLFLAG_RD, 174 &tcbinfo.ipi_count, 0, "Number of active PCBs"); 175 176static int icmp_may_rst = 1; 177SYSCTL_INT(_net_inet_tcp, OID_AUTO, icmp_may_rst, CTLFLAG_RW, &icmp_may_rst, 0, 178 "Certain ICMP unreachable messages may abort connections in SYN_SENT"); 179 180static int tcp_isn_reseed_interval = 0; 181SYSCTL_INT(_net_inet_tcp, OID_AUTO, isn_reseed_interval, CTLFLAG_RW, 182 &tcp_isn_reseed_interval, 0, "Seconds between reseeding of ISN secret"); 183 184/* 185 * TCP bandwidth limiting sysctls. Note that the default lower bound of 186 * 1024 exists only for debugging. A good production default would be 187 * something like 6100. 188 */ 189static int tcp_inflight_enable = 1; 190SYSCTL_INT(_net_inet_tcp, OID_AUTO, inflight_enable, CTLFLAG_RW, 191 &tcp_inflight_enable, 0, "Enable automatic TCP inflight data limiting"); 192 193static int tcp_inflight_debug = 0; 194SYSCTL_INT(_net_inet_tcp, OID_AUTO, inflight_debug, CTLFLAG_RW, 195 &tcp_inflight_debug, 0, "Debug TCP inflight calculations"); 196 197static int tcp_inflight_min = 6144; 198SYSCTL_INT(_net_inet_tcp, OID_AUTO, inflight_min, CTLFLAG_RW, 199 &tcp_inflight_min, 0, "Lower-bound for TCP inflight window"); 200 201static int tcp_inflight_max = TCP_MAXWIN << TCP_MAX_WINSHIFT; 202SYSCTL_INT(_net_inet_tcp, OID_AUTO, inflight_max, CTLFLAG_RW, 203 &tcp_inflight_max, 0, "Upper-bound for TCP inflight window"); 204static int tcp_inflight_stab = 20; 205SYSCTL_INT(_net_inet_tcp, OID_AUTO, inflight_stab, CTLFLAG_RW, 206 &tcp_inflight_stab, 0, "Inflight Algorithm Stabilization 20 = 2 packets"); 207 208static struct inpcb *tcp_notify(struct inpcb *, int); 209static void tcp_discardcb(struct tcpcb *); 210 211/* 212 * Target size of TCP PCB hash tables. Must be a power of two. 213 * 214 * Note that this can be overridden by the kernel environment 215 * variable net.inet.tcp.tcbhashsize 216 */ 217#ifndef TCBHASHSIZE 218#define TCBHASHSIZE 512 219#endif 220 221/* 222 * XXX 223 * Callouts should be moved into struct tcp directly. They are currently 224 * separate because the tcpcb structure is exported to userland for sysctl 225 * parsing purposes, which do not know about callouts. 226 */ 227struct tcpcb_mem { 228 struct tcpcb tcb; 229 struct callout tcpcb_mem_rexmt, tcpcb_mem_persist, tcpcb_mem_keep; 230 struct callout tcpcb_mem_2msl, tcpcb_mem_delack; 231}; 232 233static uma_zone_t tcpcb_zone; 234static uma_zone_t tcptw_zone; 235 236/* 237 * Tcp initialization 238 */ 239void 240tcp_init() 241{ 242 int hashsize = TCBHASHSIZE; 243 244 tcp_ccgen = 1; 245 246 tcp_delacktime = TCPTV_DELACK; 247 tcp_keepinit = TCPTV_KEEP_INIT; 248 tcp_keepidle = TCPTV_KEEP_IDLE; 249 tcp_keepintvl = TCPTV_KEEPINTVL; 250 tcp_maxpersistidle = TCPTV_KEEP_IDLE; 251 tcp_msl = TCPTV_MSL; 252 tcp_rexmit_min = TCPTV_MIN; 253 tcp_rexmit_slop = TCPTV_CPU_VAR; 254 255 INP_INFO_LOCK_INIT(&tcbinfo, "tcp"); 256 LIST_INIT(&tcb); 257 tcbinfo.listhead = &tcb; 258 TUNABLE_INT_FETCH("net.inet.tcp.tcbhashsize", &hashsize); 259 if (!powerof2(hashsize)) { 260 printf("WARNING: TCB hash size not a power of 2\n"); 261 hashsize = 512; /* safe default */ 262 } 263 tcp_tcbhashsize = hashsize; 264 tcbinfo.hashbase = hashinit(hashsize, M_PCB, &tcbinfo.hashmask); 265 tcbinfo.porthashbase = hashinit(hashsize, M_PCB, 266 &tcbinfo.porthashmask); 267 tcbinfo.ipi_zone = uma_zcreate("inpcb", sizeof(struct inpcb), 268 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); 269 uma_zone_set_max(tcbinfo.ipi_zone, maxsockets); 270#ifdef INET6 271#define TCP_MINPROTOHDR (sizeof(struct ip6_hdr) + sizeof(struct tcphdr)) 272#else /* INET6 */ 273#define TCP_MINPROTOHDR (sizeof(struct tcpiphdr)) 274#endif /* INET6 */ 275 if (max_protohdr < TCP_MINPROTOHDR) 276 max_protohdr = TCP_MINPROTOHDR; 277 if (max_linkhdr + TCP_MINPROTOHDR > MHLEN) 278 panic("tcp_init"); 279#undef TCP_MINPROTOHDR 280 /* 281 * These have to be type stable for the benefit of the timers. 282 */ 283 tcpcb_zone = uma_zcreate("tcpcb", sizeof(struct tcpcb_mem), 284 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); 285 uma_zone_set_max(tcpcb_zone, maxsockets); 286 tcptw_zone = uma_zcreate("tcptw", sizeof(struct tcptw), 287 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); 288 uma_zone_set_max(tcptw_zone, maxsockets / 5); 289 tcp_timer_init(); 290 syncache_init(); 291 tcp_hc_init(); 292} 293 294/* 295 * Fill in the IP and TCP headers for an outgoing packet, given the tcpcb. 296 * tcp_template used to store this data in mbufs, but we now recopy it out 297 * of the tcpcb each time to conserve mbufs. 298 */ 299void 300tcpip_fillheaders(inp, ip_ptr, tcp_ptr) 301 struct inpcb *inp; 302 void *ip_ptr; 303 void *tcp_ptr; 304{ 305 struct tcphdr *th = (struct tcphdr *)tcp_ptr; 306 307#ifdef INET6 308 if ((inp->inp_vflag & INP_IPV6) != 0) { 309 struct ip6_hdr *ip6; 310 311 ip6 = (struct ip6_hdr *)ip_ptr; 312 ip6->ip6_flow = (ip6->ip6_flow & ~IPV6_FLOWINFO_MASK) | 313 (inp->in6p_flowinfo & IPV6_FLOWINFO_MASK); 314 ip6->ip6_vfc = (ip6->ip6_vfc & ~IPV6_VERSION_MASK) | 315 (IPV6_VERSION & IPV6_VERSION_MASK); 316 ip6->ip6_nxt = IPPROTO_TCP; 317 ip6->ip6_plen = sizeof(struct tcphdr); 318 ip6->ip6_src = inp->in6p_laddr; 319 ip6->ip6_dst = inp->in6p_faddr; 320 } else 321#endif 322 { 323 struct ip *ip; 324 325 ip = (struct ip *)ip_ptr; 326 ip->ip_v = IPVERSION; 327 ip->ip_hl = 5; 328 ip->ip_tos = inp->inp_ip_tos; 329 ip->ip_len = 0; 330 ip->ip_id = 0; 331 ip->ip_off = 0; 332 ip->ip_ttl = inp->inp_ip_ttl; 333 ip->ip_sum = 0; 334 ip->ip_p = IPPROTO_TCP; 335 ip->ip_src = inp->inp_laddr; 336 ip->ip_dst = inp->inp_faddr; 337 } 338 th->th_sport = inp->inp_lport; 339 th->th_dport = inp->inp_fport; 340 th->th_seq = 0; 341 th->th_ack = 0; 342 th->th_x2 = 0; 343 th->th_off = 5; 344 th->th_flags = 0; 345 th->th_win = 0; 346 th->th_urp = 0; 347 th->th_sum = 0; /* in_pseudo() is called later for ipv4 */ 348} 349 350/* 351 * Create template to be used to send tcp packets on a connection. 352 * Allocates an mbuf and fills in a skeletal tcp/ip header. The only 353 * use for this function is in keepalives, which use tcp_respond. 354 */ 355struct tcptemp * 356tcpip_maketemplate(inp) 357 struct inpcb *inp; 358{ 359 struct mbuf *m; 360 struct tcptemp *n; 361 362 m = m_get(M_DONTWAIT, MT_HEADER); 363 if (m == NULL) 364 return (0); 365 m->m_len = sizeof(struct tcptemp); 366 n = mtod(m, struct tcptemp *); 367 368 tcpip_fillheaders(inp, (void *)&n->tt_ipgen, (void *)&n->tt_t); 369 return (n); 370} 371 372/* 373 * Send a single message to the TCP at address specified by 374 * the given TCP/IP header. If m == 0, then we make a copy 375 * of the tcpiphdr at ti and send directly to the addressed host. 376 * This is used to force keep alive messages out using the TCP 377 * template for a connection. If flags are given then we send 378 * a message back to the TCP which originated the * segment ti, 379 * and discard the mbuf containing it and any other attached mbufs. 380 * 381 * In any case the ack and sequence number of the transmitted 382 * segment are as specified by the parameters. 383 * 384 * NOTE: If m != NULL, then ti must point to *inside* the mbuf. 385 */ 386void 387tcp_respond(tp, ipgen, th, m, ack, seq, flags) 388 struct tcpcb *tp; 389 void *ipgen; 390 register struct tcphdr *th; 391 register struct mbuf *m; 392 tcp_seq ack, seq; 393 int flags; 394{ 395 register int tlen; 396 int win = 0; 397 struct ip *ip; 398 struct tcphdr *nth; 399#ifdef INET6 400 struct ip6_hdr *ip6; 401 int isipv6; 402#endif /* INET6 */ 403 int ipflags = 0; 404 struct inpcb *inp = NULL; 405 406 KASSERT(tp != NULL || m != NULL, ("tcp_respond: tp and m both NULL")); 407 408#ifdef INET6 409 isipv6 = ((struct ip *)ipgen)->ip_v == 6; 410 ip6 = ipgen; 411#endif /* INET6 */ 412 ip = ipgen; 413 414 if (tp) { 415 inp = tp->t_inpcb; 416 KASSERT(inp != NULL, ("tcp control block w/o inpcb")); 417 INP_INFO_WLOCK_ASSERT(&tcbinfo); 418 INP_LOCK_ASSERT(inp); 419 if (!(flags & TH_RST)) { 420 win = sbspace(&inp->inp_socket->so_rcv); 421 if (win > (long)TCP_MAXWIN << tp->rcv_scale) 422 win = (long)TCP_MAXWIN << tp->rcv_scale; 423 } 424 } 425 if (m == 0) { 426 m = m_gethdr(M_DONTWAIT, MT_HEADER); 427 if (m == NULL) 428 return; 429 tlen = 0; 430 m->m_data += max_linkhdr; 431#ifdef INET6 432 if (isipv6) { 433 bcopy((caddr_t)ip6, mtod(m, caddr_t), 434 sizeof(struct ip6_hdr)); 435 ip6 = mtod(m, struct ip6_hdr *); 436 nth = (struct tcphdr *)(ip6 + 1); 437 } else 438#endif /* INET6 */ 439 { 440 bcopy((caddr_t)ip, mtod(m, caddr_t), sizeof(struct ip)); 441 ip = mtod(m, struct ip *); 442 nth = (struct tcphdr *)(ip + 1); 443 } 444 bcopy((caddr_t)th, (caddr_t)nth, sizeof(struct tcphdr)); 445 flags = TH_ACK; 446 } else { 447 m_freem(m->m_next); 448 m->m_next = 0; 449 m->m_data = (caddr_t)ipgen; 450 /* m_len is set later */ 451 tlen = 0; 452#define xchg(a,b,type) { type t; t=a; a=b; b=t; } 453#ifdef INET6 454 if (isipv6) { 455 xchg(ip6->ip6_dst, ip6->ip6_src, struct in6_addr); 456 nth = (struct tcphdr *)(ip6 + 1); 457 } else 458#endif /* INET6 */ 459 { 460 xchg(ip->ip_dst.s_addr, ip->ip_src.s_addr, n_long); 461 nth = (struct tcphdr *)(ip + 1); 462 } 463 if (th != nth) { 464 /* 465 * this is usually a case when an extension header 466 * exists between the IPv6 header and the 467 * TCP header. 468 */ 469 nth->th_sport = th->th_sport; 470 nth->th_dport = th->th_dport; 471 } 472 xchg(nth->th_dport, nth->th_sport, n_short); 473#undef xchg 474 } 475#ifdef INET6 476 if (isipv6) { 477 ip6->ip6_flow = 0; 478 ip6->ip6_vfc = IPV6_VERSION; 479 ip6->ip6_nxt = IPPROTO_TCP; 480 ip6->ip6_plen = htons((u_short)(sizeof (struct tcphdr) + 481 tlen)); 482 tlen += sizeof (struct ip6_hdr) + sizeof (struct tcphdr); 483 } else 484#endif 485 { 486 tlen += sizeof (struct tcpiphdr); 487 ip->ip_len = tlen; 488 ip->ip_ttl = ip_defttl; 489 if (path_mtu_discovery) 490 ip->ip_off |= IP_DF; 491 } 492 m->m_len = tlen; 493 m->m_pkthdr.len = tlen; 494 m->m_pkthdr.rcvif = (struct ifnet *) 0; 495#ifdef MAC 496 if (inp != NULL) { 497 /* 498 * Packet is associated with a socket, so allow the 499 * label of the response to reflect the socket label. 500 */ 501 mac_create_mbuf_from_socket(inp->inp_socket, m); 502 } else { 503 /* 504 * Packet is not associated with a socket, so possibly 505 * update the label in place. 506 */ 507 mac_reflect_mbuf_tcp(m); 508 } 509#endif 510 nth->th_seq = htonl(seq); 511 nth->th_ack = htonl(ack); 512 nth->th_x2 = 0; 513 nth->th_off = sizeof (struct tcphdr) >> 2; 514 nth->th_flags = flags; 515 if (tp) 516 nth->th_win = htons((u_short) (win >> tp->rcv_scale)); 517 else 518 nth->th_win = htons((u_short)win); 519 nth->th_urp = 0; 520#ifdef INET6 521 if (isipv6) { 522 nth->th_sum = 0; 523 nth->th_sum = in6_cksum(m, IPPROTO_TCP, 524 sizeof(struct ip6_hdr), 525 tlen - sizeof(struct ip6_hdr)); 526 ip6->ip6_hlim = in6_selecthlim(tp ? tp->t_inpcb : NULL, NULL); 527 } else 528#endif /* INET6 */ 529 { 530 nth->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr, 531 htons((u_short)(tlen - sizeof(struct ip) + ip->ip_p))); 532 m->m_pkthdr.csum_flags = CSUM_TCP; 533 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 534 } 535#ifdef TCPDEBUG 536 if (tp == NULL || (inp->inp_socket->so_options & SO_DEBUG)) 537 tcp_trace(TA_OUTPUT, 0, tp, mtod(m, void *), th, 0); 538#endif 539#ifdef INET6 540 if (isipv6) 541 (void) ip6_output(m, NULL, NULL, ipflags, NULL, NULL, inp); 542 else 543#endif /* INET6 */ 544 (void) ip_output(m, NULL, NULL, ipflags, NULL, inp); 545} 546 547/* 548 * Create a new TCP control block, making an 549 * empty reassembly queue and hooking it to the argument 550 * protocol control block. The `inp' parameter must have 551 * come from the zone allocator set up in tcp_init(). 552 */ 553struct tcpcb * 554tcp_newtcpcb(inp) 555 struct inpcb *inp; 556{ 557 struct tcpcb_mem *tm; 558 struct tcpcb *tp; 559#ifdef INET6 560 int isipv6 = (inp->inp_vflag & INP_IPV6) != 0; 561#endif /* INET6 */ 562 563 tm = uma_zalloc(tcpcb_zone, M_NOWAIT | M_ZERO); 564 if (tm == NULL) 565 return (NULL); 566 tp = &tm->tcb; 567 /* LIST_INIT(&tp->t_segq); */ /* XXX covered by M_ZERO */ 568 tp->t_maxseg = tp->t_maxopd = 569#ifdef INET6 570 isipv6 ? tcp_v6mssdflt : 571#endif /* INET6 */ 572 tcp_mssdflt; 573 574 /* Set up our timeouts. */ 575 callout_init(tp->tt_rexmt = &tm->tcpcb_mem_rexmt, 0); 576 callout_init(tp->tt_persist = &tm->tcpcb_mem_persist, 0); 577 callout_init(tp->tt_keep = &tm->tcpcb_mem_keep, 0); 578 callout_init(tp->tt_2msl = &tm->tcpcb_mem_2msl, 0); 579 callout_init(tp->tt_delack = &tm->tcpcb_mem_delack, 0); 580 581 if (tcp_do_rfc1323) 582 tp->t_flags = (TF_REQ_SCALE|TF_REQ_TSTMP); 583 if (tcp_do_rfc1644) 584 tp->t_flags |= TF_REQ_CC; 585 tp->t_inpcb = inp; /* XXX */ 586 /* 587 * Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no 588 * rtt estimate. Set rttvar so that srtt + 4 * rttvar gives 589 * reasonable initial retransmit time. 590 */ 591 tp->t_srtt = TCPTV_SRTTBASE; 592 tp->t_rttvar = ((TCPTV_RTOBASE - TCPTV_SRTTBASE) << TCP_RTTVAR_SHIFT) / 4; 593 tp->t_rttmin = tcp_rexmit_min; 594 tp->t_rxtcur = TCPTV_RTOBASE; 595 tp->snd_cwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 596 tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 597 tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT; 598 tp->t_rcvtime = ticks; 599 tp->t_bw_rtttime = ticks; 600 /* 601 * IPv4 TTL initialization is necessary for an IPv6 socket as well, 602 * because the socket may be bound to an IPv6 wildcard address, 603 * which may match an IPv4-mapped IPv6 address. 604 */ 605 inp->inp_ip_ttl = ip_defttl; 606 inp->inp_ppcb = (caddr_t)tp; 607 return (tp); /* XXX */ 608} 609 610/* 611 * Drop a TCP connection, reporting 612 * the specified error. If connection is synchronized, 613 * then send a RST to peer. 614 */ 615struct tcpcb * 616tcp_drop(tp, errno) 617 register struct tcpcb *tp; 618 int errno; 619{ 620 struct socket *so = tp->t_inpcb->inp_socket; 621 622 if (TCPS_HAVERCVDSYN(tp->t_state)) { 623 tp->t_state = TCPS_CLOSED; 624 (void) tcp_output(tp); 625 tcpstat.tcps_drops++; 626 } else 627 tcpstat.tcps_conndrops++; 628 if (errno == ETIMEDOUT && tp->t_softerror) 629 errno = tp->t_softerror; 630 so->so_error = errno; 631 return (tcp_close(tp)); 632} 633 634static void 635tcp_discardcb(tp) 636 struct tcpcb *tp; 637{ 638 struct tseg_qent *q; 639 struct inpcb *inp = tp->t_inpcb; 640 struct socket *so = inp->inp_socket; 641#ifdef INET6 642 int isipv6 = (inp->inp_vflag & INP_IPV6) != 0; 643#endif /* INET6 */ 644 645 /* 646 * Make sure that all of our timers are stopped before we 647 * delete the PCB. 648 */ 649 callout_stop(tp->tt_rexmt); 650 callout_stop(tp->tt_persist); 651 callout_stop(tp->tt_keep); 652 callout_stop(tp->tt_2msl); 653 callout_stop(tp->tt_delack); 654 655 /* 656 * If we got enough samples through the srtt filter, 657 * save the rtt and rttvar in the routing entry. 658 * 'Enough' is arbitrarily defined as 4 rtt samples. 659 * 4 samples is enough for the srtt filter to converge 660 * to within enough % of the correct value; fewer samples 661 * and we could save a bogus rtt. The danger is not high 662 * as tcp quickly recovers from everything. 663 * XXX: Works very well but needs some more statistics! 664 */ 665 if (tp->t_rttupdated >= 4) { 666 struct hc_metrics_lite metrics; 667 u_long ssthresh; 668 669 bzero(&metrics, sizeof(metrics)); 670 /* 671 * Update the ssthresh always when the conditions below 672 * are satisfied. This gives us better new start value 673 * for the congestion avoidance for new connections. 674 * ssthresh is only set if packet loss occured on a session. 675 */ 676 ssthresh = tp->snd_ssthresh; 677 if (ssthresh != 0 && ssthresh < so->so_snd.sb_hiwat / 2) { 678 /* 679 * convert the limit from user data bytes to 680 * packets then to packet data bytes. 681 */ 682 ssthresh = (ssthresh + tp->t_maxseg / 2) / tp->t_maxseg; 683 if (ssthresh < 2) 684 ssthresh = 2; 685 ssthresh *= (u_long)(tp->t_maxseg + 686#ifdef INET6 687 (isipv6 ? sizeof (struct ip6_hdr) + 688 sizeof (struct tcphdr) : 689#endif 690 sizeof (struct tcpiphdr) 691#ifdef INET6 692 ) 693#endif 694 ); 695 } else 696 ssthresh = 0; 697 metrics.rmx_ssthresh = ssthresh; 698 699 metrics.rmx_rtt = tp->t_srtt; 700 metrics.rmx_rttvar = tp->t_rttvar; 701 /* XXX: This wraps if the pipe is more than 4 Gbit per second */ 702 metrics.rmx_bandwidth = tp->snd_bandwidth; 703 metrics.rmx_cwnd = tp->snd_cwnd; 704 metrics.rmx_sendpipe = 0; 705 metrics.rmx_recvpipe = 0; 706 707 tcp_hc_update(&inp->inp_inc, &metrics); 708 } 709 710 /* free the reassembly queue, if any */ 711 while ((q = LIST_FIRST(&tp->t_segq)) != NULL) { 712 LIST_REMOVE(q, tqe_q); 713 m_freem(q->tqe_m); 714 FREE(q, M_TSEGQ); 715 } 716 inp->inp_ppcb = NULL; 717 tp->t_inpcb = NULL; 718 uma_zfree(tcpcb_zone, tp); 719 soisdisconnected(so); 720} 721 722/* 723 * Close a TCP control block: 724 * discard all space held by the tcp 725 * discard internet protocol block 726 * wake up any sleepers 727 */ 728struct tcpcb * 729tcp_close(tp) 730 struct tcpcb *tp; 731{ 732 struct inpcb *inp = tp->t_inpcb; 733#ifdef INET6 734 struct socket *so = inp->inp_socket; 735#endif 736 737 tcp_discardcb(tp); 738#ifdef INET6 739 if (INP_CHECK_SOCKAF(so, AF_INET6)) 740 in6_pcbdetach(inp); 741 else 742#endif 743 in_pcbdetach(inp); 744 tcpstat.tcps_closed++; 745 return ((struct tcpcb *)0); 746} 747 748void 749tcp_drain() 750{ 751 if (do_tcpdrain) 752 { 753 struct inpcb *inpb; 754 struct tcpcb *tcpb; 755 struct tseg_qent *te; 756 757 /* 758 * Walk the tcpbs, if existing, and flush the reassembly queue, 759 * if there is one... 760 * XXX: The "Net/3" implementation doesn't imply that the TCP 761 * reassembly queue should be flushed, but in a situation 762 * where we're really low on mbufs, this is potentially 763 * usefull. 764 */ 765 INP_INFO_RLOCK(&tcbinfo); 766 LIST_FOREACH(inpb, tcbinfo.listhead, inp_list) { 767 if (inpb->inp_vflag & INP_TIMEWAIT) 768 continue; 769 INP_LOCK(inpb); 770 if ((tcpb = intotcpcb(inpb))) { 771 while ((te = LIST_FIRST(&tcpb->t_segq)) 772 != NULL) { 773 LIST_REMOVE(te, tqe_q); 774 m_freem(te->tqe_m); 775 FREE(te, M_TSEGQ); 776 } 777 } 778 INP_UNLOCK(inpb); 779 } 780 INP_INFO_RUNLOCK(&tcbinfo); 781 } 782} 783 784/* 785 * Notify a tcp user of an asynchronous error; 786 * store error as soft error, but wake up user 787 * (for now, won't do anything until can select for soft error). 788 * 789 * Do not wake up user since there currently is no mechanism for 790 * reporting soft errors (yet - a kqueue filter may be added). 791 */ 792static struct inpcb * 793tcp_notify(inp, error) 794 struct inpcb *inp; 795 int error; 796{ 797 struct tcpcb *tp = (struct tcpcb *)inp->inp_ppcb; 798 799 /* 800 * Ignore some errors if we are hooked up. 801 * If connection hasn't completed, has retransmitted several times, 802 * and receives a second error, give up now. This is better 803 * than waiting a long time to establish a connection that 804 * can never complete. 805 */ 806 if (tp->t_state == TCPS_ESTABLISHED && 807 (error == EHOSTUNREACH || error == ENETUNREACH || 808 error == EHOSTDOWN)) { 809 return inp; 810 } else if (tp->t_state < TCPS_ESTABLISHED && tp->t_rxtshift > 3 && 811 tp->t_softerror) { 812 tcp_drop(tp, error); 813 return (struct inpcb *)0; 814 } else { 815 tp->t_softerror = error; 816 return inp; 817 } 818#if 0 819 wakeup( &so->so_timeo); 820 sorwakeup(so); 821 sowwakeup(so); 822#endif 823} 824 825static int 826tcp_pcblist(SYSCTL_HANDLER_ARGS) 827{ 828 int error, i, n, s; 829 struct inpcb *inp, **inp_list; 830 inp_gen_t gencnt; 831 struct xinpgen xig; 832 833 /* 834 * The process of preparing the TCB list is too time-consuming and 835 * resource-intensive to repeat twice on every request. 836 */ 837 if (req->oldptr == 0) { 838 n = tcbinfo.ipi_count; 839 req->oldidx = 2 * (sizeof xig) 840 + (n + n/8) * sizeof(struct xtcpcb); 841 return 0; 842 } 843 844 if (req->newptr != 0) 845 return EPERM; 846 847 /* 848 * OK, now we're committed to doing something. 849 */ 850 s = splnet(); 851 INP_INFO_RLOCK(&tcbinfo); 852 gencnt = tcbinfo.ipi_gencnt; 853 n = tcbinfo.ipi_count; 854 INP_INFO_RUNLOCK(&tcbinfo); 855 splx(s); 856 857 sysctl_wire_old_buffer(req, 2 * (sizeof xig) 858 + n * sizeof(struct xtcpcb)); 859 860 xig.xig_len = sizeof xig; 861 xig.xig_count = n; 862 xig.xig_gen = gencnt; 863 xig.xig_sogen = so_gencnt; 864 error = SYSCTL_OUT(req, &xig, sizeof xig); 865 if (error) 866 return error; 867 868 inp_list = malloc(n * sizeof *inp_list, M_TEMP, M_WAITOK); 869 if (inp_list == 0) 870 return ENOMEM; 871 872 s = splnet(); 873 INP_INFO_RLOCK(&tcbinfo); 874 for (inp = LIST_FIRST(tcbinfo.listhead), i = 0; inp && i < n; 875 inp = LIST_NEXT(inp, inp_list)) { 876 INP_LOCK(inp); 877 if (inp->inp_gencnt <= gencnt) { 878 /* 879 * XXX: This use of cr_cansee(), introduced with 880 * TCP state changes, is not quite right, but for 881 * now, better than nothing. 882 */ 883 if (inp->inp_vflag & INP_TIMEWAIT) 884 error = cr_cansee(req->td->td_ucred, 885 intotw(inp)->tw_cred); 886 else 887 error = cr_canseesocket(req->td->td_ucred, 888 inp->inp_socket); 889 if (error == 0) 890 inp_list[i++] = inp; 891 } 892 INP_UNLOCK(inp); 893 } 894 INP_INFO_RUNLOCK(&tcbinfo); 895 splx(s); 896 n = i; 897 898 error = 0; 899 for (i = 0; i < n; i++) { 900 inp = inp_list[i]; 901 if (inp->inp_gencnt <= gencnt) { 902 struct xtcpcb xt; 903 caddr_t inp_ppcb; 904 xt.xt_len = sizeof xt; 905 /* XXX should avoid extra copy */ 906 bcopy(inp, &xt.xt_inp, sizeof *inp); 907 inp_ppcb = inp->inp_ppcb; 908 if (inp_ppcb == NULL) 909 bzero((char *) &xt.xt_tp, sizeof xt.xt_tp); 910 else if (inp->inp_vflag & INP_TIMEWAIT) { 911 bzero((char *) &xt.xt_tp, sizeof xt.xt_tp); 912 xt.xt_tp.t_state = TCPS_TIME_WAIT; 913 } else 914 bcopy(inp_ppcb, &xt.xt_tp, sizeof xt.xt_tp); 915 if (inp->inp_socket) 916 sotoxsocket(inp->inp_socket, &xt.xt_socket); 917 else { 918 bzero(&xt.xt_socket, sizeof xt.xt_socket); 919 xt.xt_socket.xso_protocol = IPPROTO_TCP; 920 } 921 xt.xt_inp.inp_gencnt = inp->inp_gencnt; 922 error = SYSCTL_OUT(req, &xt, sizeof xt); 923 } 924 } 925 if (!error) { 926 /* 927 * Give the user an updated idea of our state. 928 * If the generation differs from what we told 929 * her before, she knows that something happened 930 * while we were processing this request, and it 931 * might be necessary to retry. 932 */ 933 s = splnet(); 934 INP_INFO_RLOCK(&tcbinfo); 935 xig.xig_gen = tcbinfo.ipi_gencnt; 936 xig.xig_sogen = so_gencnt; 937 xig.xig_count = tcbinfo.ipi_count; 938 INP_INFO_RUNLOCK(&tcbinfo); 939 splx(s); 940 error = SYSCTL_OUT(req, &xig, sizeof xig); 941 } 942 free(inp_list, M_TEMP); 943 return error; 944} 945 946SYSCTL_PROC(_net_inet_tcp, TCPCTL_PCBLIST, pcblist, CTLFLAG_RD, 0, 0, 947 tcp_pcblist, "S,xtcpcb", "List of active TCP connections"); 948 949static int 950tcp_getcred(SYSCTL_HANDLER_ARGS) 951{ 952 struct xucred xuc; 953 struct sockaddr_in addrs[2]; 954 struct inpcb *inp; 955 int error, s; 956 957 error = suser_cred(req->td->td_ucred, PRISON_ROOT); 958 if (error) 959 return (error); 960 error = SYSCTL_IN(req, addrs, sizeof(addrs)); 961 if (error) 962 return (error); 963 s = splnet(); 964 INP_INFO_RLOCK(&tcbinfo); 965 inp = in_pcblookup_hash(&tcbinfo, addrs[1].sin_addr, addrs[1].sin_port, 966 addrs[0].sin_addr, addrs[0].sin_port, 0, NULL); 967 if (inp == NULL) { 968 error = ENOENT; 969 goto outunlocked; 970 } 971 INP_LOCK(inp); 972 if (inp->inp_socket == NULL) { 973 error = ENOENT; 974 goto out; 975 } 976 error = cr_canseesocket(req->td->td_ucred, inp->inp_socket); 977 if (error) 978 goto out; 979 cru2x(inp->inp_socket->so_cred, &xuc); 980out: 981 INP_UNLOCK(inp); 982outunlocked: 983 INP_INFO_RUNLOCK(&tcbinfo); 984 splx(s); 985 if (error == 0) 986 error = SYSCTL_OUT(req, &xuc, sizeof(struct xucred)); 987 return (error); 988} 989 990SYSCTL_PROC(_net_inet_tcp, OID_AUTO, getcred, 991 CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_PRISON, 0, 0, 992 tcp_getcred, "S,xucred", "Get the xucred of a TCP connection"); 993 994#ifdef INET6 995static int 996tcp6_getcred(SYSCTL_HANDLER_ARGS) 997{ 998 struct xucred xuc; 999 struct sockaddr_in6 addrs[2]; 1000 struct inpcb *inp; 1001 int error, s, mapped = 0; 1002 1003 error = suser_cred(req->td->td_ucred, PRISON_ROOT); 1004 if (error) 1005 return (error); 1006 error = SYSCTL_IN(req, addrs, sizeof(addrs)); 1007 if (error) 1008 return (error); 1009 if (IN6_IS_ADDR_V4MAPPED(&addrs[0].sin6_addr)) { 1010 if (IN6_IS_ADDR_V4MAPPED(&addrs[1].sin6_addr)) 1011 mapped = 1; 1012 else 1013 return (EINVAL); 1014 } 1015 s = splnet(); 1016 INP_INFO_RLOCK(&tcbinfo); 1017 if (mapped == 1) 1018 inp = in_pcblookup_hash(&tcbinfo, 1019 *(struct in_addr *)&addrs[1].sin6_addr.s6_addr[12], 1020 addrs[1].sin6_port, 1021 *(struct in_addr *)&addrs[0].sin6_addr.s6_addr[12], 1022 addrs[0].sin6_port, 1023 0, NULL); 1024 else 1025 inp = in6_pcblookup_hash(&tcbinfo, &addrs[1].sin6_addr, 1026 addrs[1].sin6_port, 1027 &addrs[0].sin6_addr, addrs[0].sin6_port, 1028 0, NULL); 1029 if (inp == NULL) { 1030 error = ENOENT; 1031 goto outunlocked; 1032 } 1033 INP_LOCK(inp); 1034 if (inp->inp_socket == NULL) { 1035 error = ENOENT; 1036 goto out; 1037 } 1038 error = cr_canseesocket(req->td->td_ucred, inp->inp_socket); 1039 if (error) 1040 goto out; 1041 cru2x(inp->inp_socket->so_cred, &xuc); 1042out: 1043 INP_UNLOCK(inp); 1044outunlocked: 1045 INP_INFO_RUNLOCK(&tcbinfo); 1046 splx(s); 1047 if (error == 0) 1048 error = SYSCTL_OUT(req, &xuc, sizeof(struct xucred)); 1049 return (error); 1050} 1051 1052SYSCTL_PROC(_net_inet6_tcp6, OID_AUTO, getcred, 1053 CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_PRISON, 0, 0, 1054 tcp6_getcred, "S,xucred", "Get the xucred of a TCP6 connection"); 1055#endif 1056 1057 1058void 1059tcp_ctlinput(cmd, sa, vip) 1060 int cmd; 1061 struct sockaddr *sa; 1062 void *vip; 1063{ 1064 struct ip *ip = vip; 1065 struct tcphdr *th; 1066 struct in_addr faddr; 1067 struct inpcb *inp; 1068 struct tcpcb *tp; 1069 struct inpcb *(*notify)(struct inpcb *, int) = tcp_notify; 1070 tcp_seq icmp_seq; 1071 int s; 1072 1073 faddr = ((struct sockaddr_in *)sa)->sin_addr; 1074 if (sa->sa_family != AF_INET || faddr.s_addr == INADDR_ANY) 1075 return; 1076 1077 if (cmd == PRC_QUENCH) 1078 notify = tcp_quench; 1079 else if (icmp_may_rst && (cmd == PRC_UNREACH_ADMIN_PROHIB || 1080 cmd == PRC_UNREACH_PORT || cmd == PRC_TIMXCEED_INTRANS) && ip) 1081 notify = tcp_drop_syn_sent; 1082 else if (cmd == PRC_MSGSIZE) 1083 notify = tcp_mtudisc; 1084 /* 1085 * Redirects don't need to be handled up here. 1086 */ 1087 else if (PRC_IS_REDIRECT(cmd)) 1088 return; 1089 /* 1090 * Hostdead is ugly because it goes linearly through all PCBs. 1091 * XXX: We never get this from ICMP, otherwise it makes an 1092 * excellent DoS attack on machines with many connections. 1093 */ 1094 else if (cmd == PRC_HOSTDEAD) 1095 ip = 0; 1096 else if ((unsigned)cmd >= PRC_NCMDS || inetctlerrmap[cmd] == 0) 1097 return; 1098 if (ip) { 1099 s = splnet(); 1100 th = (struct tcphdr *)((caddr_t)ip 1101 + (ip->ip_hl << 2)); 1102 INP_INFO_WLOCK(&tcbinfo); 1103 inp = in_pcblookup_hash(&tcbinfo, faddr, th->th_dport, 1104 ip->ip_src, th->th_sport, 0, NULL); 1105 if (inp != NULL) { 1106 INP_LOCK(inp); 1107 if (inp->inp_socket != NULL) { 1108 icmp_seq = htonl(th->th_seq); 1109 tp = intotcpcb(inp); 1110 if (SEQ_GEQ(icmp_seq, tp->snd_una) && 1111 SEQ_LT(icmp_seq, tp->snd_max)) 1112 inp = (*notify)(inp, inetctlerrmap[cmd]); 1113 } 1114 if (inp) 1115 INP_UNLOCK(inp); 1116 } else { 1117 struct in_conninfo inc; 1118 1119 inc.inc_fport = th->th_dport; 1120 inc.inc_lport = th->th_sport; 1121 inc.inc_faddr = faddr; 1122 inc.inc_laddr = ip->ip_src; 1123#ifdef INET6 1124 inc.inc_isipv6 = 0; 1125#endif 1126 syncache_unreach(&inc, th); 1127 } 1128 INP_INFO_WUNLOCK(&tcbinfo); 1129 splx(s); 1130 } else 1131 in_pcbnotifyall(&tcbinfo, faddr, inetctlerrmap[cmd], notify); 1132} 1133 1134#ifdef INET6 1135void 1136tcp6_ctlinput(cmd, sa, d) 1137 int cmd; 1138 struct sockaddr *sa; 1139 void *d; 1140{ 1141 struct tcphdr th; 1142 struct inpcb *(*notify)(struct inpcb *, int) = tcp_notify; 1143 struct ip6_hdr *ip6; 1144 struct mbuf *m; 1145 struct ip6ctlparam *ip6cp = NULL; 1146 const struct sockaddr_in6 *sa6_src = NULL; 1147 int off; 1148 struct tcp_portonly { 1149 u_int16_t th_sport; 1150 u_int16_t th_dport; 1151 } *thp; 1152 1153 if (sa->sa_family != AF_INET6 || 1154 sa->sa_len != sizeof(struct sockaddr_in6)) 1155 return; 1156 1157 if (cmd == PRC_QUENCH) 1158 notify = tcp_quench; 1159 else if (cmd == PRC_MSGSIZE) 1160 notify = tcp_mtudisc; 1161 else if (!PRC_IS_REDIRECT(cmd) && 1162 ((unsigned)cmd >= PRC_NCMDS || inet6ctlerrmap[cmd] == 0)) 1163 return; 1164 1165 /* if the parameter is from icmp6, decode it. */ 1166 if (d != NULL) { 1167 ip6cp = (struct ip6ctlparam *)d; 1168 m = ip6cp->ip6c_m; 1169 ip6 = ip6cp->ip6c_ip6; 1170 off = ip6cp->ip6c_off; 1171 sa6_src = ip6cp->ip6c_src; 1172 } else { 1173 m = NULL; 1174 ip6 = NULL; 1175 off = 0; /* fool gcc */ 1176 sa6_src = &sa6_any; 1177 } 1178 1179 if (ip6) { 1180 struct in_conninfo inc; 1181 /* 1182 * XXX: We assume that when IPV6 is non NULL, 1183 * M and OFF are valid. 1184 */ 1185 1186 /* check if we can safely examine src and dst ports */ 1187 if (m->m_pkthdr.len < off + sizeof(*thp)) 1188 return; 1189 1190 bzero(&th, sizeof(th)); 1191 m_copydata(m, off, sizeof(*thp), (caddr_t)&th); 1192 1193 in6_pcbnotify(&tcb, sa, th.th_dport, 1194 (struct sockaddr *)ip6cp->ip6c_src, 1195 th.th_sport, cmd, NULL, notify); 1196 1197 inc.inc_fport = th.th_dport; 1198 inc.inc_lport = th.th_sport; 1199 inc.inc6_faddr = ((struct sockaddr_in6 *)sa)->sin6_addr; 1200 inc.inc6_laddr = ip6cp->ip6c_src->sin6_addr; 1201 inc.inc_isipv6 = 1; 1202 syncache_unreach(&inc, &th); 1203 } else 1204 in6_pcbnotify(&tcb, sa, 0, (const struct sockaddr *)sa6_src, 1205 0, cmd, NULL, notify); 1206} 1207#endif /* INET6 */ 1208 1209 1210/* 1211 * Following is where TCP initial sequence number generation occurs. 1212 * 1213 * There are two places where we must use initial sequence numbers: 1214 * 1. In SYN-ACK packets. 1215 * 2. In SYN packets. 1216 * 1217 * All ISNs for SYN-ACK packets are generated by the syncache. See 1218 * tcp_syncache.c for details. 1219 * 1220 * The ISNs in SYN packets must be monotonic; TIME_WAIT recycling 1221 * depends on this property. In addition, these ISNs should be 1222 * unguessable so as to prevent connection hijacking. To satisfy 1223 * the requirements of this situation, the algorithm outlined in 1224 * RFC 1948 is used to generate sequence numbers. 1225 * 1226 * Implementation details: 1227 * 1228 * Time is based off the system timer, and is corrected so that it 1229 * increases by one megabyte per second. This allows for proper 1230 * recycling on high speed LANs while still leaving over an hour 1231 * before rollover. 1232 * 1233 * net.inet.tcp.isn_reseed_interval controls the number of seconds 1234 * between seeding of isn_secret. This is normally set to zero, 1235 * as reseeding should not be necessary. 1236 * 1237 */ 1238 1239#define ISN_BYTES_PER_SECOND 1048576 1240 1241u_char isn_secret[32]; 1242int isn_last_reseed; 1243MD5_CTX isn_ctx; 1244 1245tcp_seq 1246tcp_new_isn(tp) 1247 struct tcpcb *tp; 1248{ 1249 u_int32_t md5_buffer[4]; 1250 tcp_seq new_isn; 1251 1252 /* Seed if this is the first use, reseed if requested. */ 1253 if ((isn_last_reseed == 0) || ((tcp_isn_reseed_interval > 0) && 1254 (((u_int)isn_last_reseed + (u_int)tcp_isn_reseed_interval*hz) 1255 < (u_int)ticks))) { 1256 read_random(&isn_secret, sizeof(isn_secret)); 1257 isn_last_reseed = ticks; 1258 } 1259 1260 /* Compute the md5 hash and return the ISN. */ 1261 MD5Init(&isn_ctx); 1262 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_fport, sizeof(u_short)); 1263 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_lport, sizeof(u_short)); 1264#ifdef INET6 1265 if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0) { 1266 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_faddr, 1267 sizeof(struct in6_addr)); 1268 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_laddr, 1269 sizeof(struct in6_addr)); 1270 } else 1271#endif 1272 { 1273 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_faddr, 1274 sizeof(struct in_addr)); 1275 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_laddr, 1276 sizeof(struct in_addr)); 1277 } 1278 MD5Update(&isn_ctx, (u_char *) &isn_secret, sizeof(isn_secret)); 1279 MD5Final((u_char *) &md5_buffer, &isn_ctx); 1280 new_isn = (tcp_seq) md5_buffer[0]; 1281 new_isn += ticks * (ISN_BYTES_PER_SECOND / hz); 1282 return new_isn; 1283} 1284 1285/* 1286 * When a source quench is received, close congestion window 1287 * to one segment. We will gradually open it again as we proceed. 1288 */ 1289struct inpcb * 1290tcp_quench(inp, errno) 1291 struct inpcb *inp; 1292 int errno; 1293{ 1294 struct tcpcb *tp = intotcpcb(inp); 1295 1296 if (tp) 1297 tp->snd_cwnd = tp->t_maxseg; 1298 return (inp); 1299} 1300 1301/* 1302 * When a specific ICMP unreachable message is received and the 1303 * connection state is SYN-SENT, drop the connection. This behavior 1304 * is controlled by the icmp_may_rst sysctl. 1305 */ 1306struct inpcb * 1307tcp_drop_syn_sent(inp, errno) 1308 struct inpcb *inp; 1309 int errno; 1310{ 1311 struct tcpcb *tp = intotcpcb(inp); 1312 1313 if (tp && tp->t_state == TCPS_SYN_SENT) { 1314 tcp_drop(tp, errno); 1315 return (struct inpcb *)0; 1316 } 1317 return inp; 1318} 1319 1320/* 1321 * When `need fragmentation' ICMP is received, update our idea of the MSS 1322 * based on the new value in the route. Also nudge TCP to send something, 1323 * since we know the packet we just sent was dropped. 1324 * This duplicates some code in the tcp_mss() function in tcp_input.c. 1325 */ 1326struct inpcb * 1327tcp_mtudisc(inp, errno) 1328 struct inpcb *inp; 1329 int errno; 1330{ 1331 struct tcpcb *tp = intotcpcb(inp); 1332 struct rmxp_tao tao; 1333 struct socket *so = inp->inp_socket; 1334 u_int maxmtu; 1335 u_int romtu; 1336 int mss; 1337#ifdef INET6 1338 int isipv6 = (tp->t_inpcb->inp_vflag & INP_IPV6) != 0; 1339#endif /* INET6 */ 1340 bzero(&tao, sizeof(tao)); 1341 1342 if (tp) { 1343 maxmtu = tcp_hc_getmtu(&inp->inp_inc); /* IPv4 and IPv6 */ 1344 romtu = 1345#ifdef INET6 1346 isipv6 ? tcp_maxmtu6(&inp->inp_inc) : 1347#endif /* INET6 */ 1348 tcp_maxmtu(&inp->inp_inc); 1349 if (!maxmtu) 1350 maxmtu = romtu; 1351 else 1352 maxmtu = min(maxmtu, romtu); 1353 if (!maxmtu) { 1354 tp->t_maxopd = tp->t_maxseg = 1355#ifdef INET6 1356 isipv6 ? tcp_v6mssdflt : 1357#endif /* INET6 */ 1358 tcp_mssdflt; 1359 return inp; 1360 } 1361 mss = maxmtu - 1362#ifdef INET6 1363 (isipv6 ? 1364 sizeof(struct ip6_hdr) + sizeof(struct tcphdr) : 1365#endif /* INET6 */ 1366 sizeof(struct tcpiphdr) 1367#ifdef INET6 1368 ) 1369#endif /* INET6 */ 1370 ; 1371 1372 if (tcp_do_rfc1644) { 1373 tcp_hc_gettao(&inp->inp_inc, &tao); 1374 if (tao.tao_mssopt) 1375 mss = min(mss, tao.tao_mssopt); 1376 } 1377 /* 1378 * XXX - The above conditional probably violates the TCP 1379 * spec. The problem is that, since we don't know the 1380 * other end's MSS, we are supposed to use a conservative 1381 * default. But, if we do that, then MTU discovery will 1382 * never actually take place, because the conservative 1383 * default is much less than the MTUs typically seen 1384 * on the Internet today. For the moment, we'll sweep 1385 * this under the carpet. 1386 * 1387 * The conservative default might not actually be a problem 1388 * if the only case this occurs is when sending an initial 1389 * SYN with options and data to a host we've never talked 1390 * to before. Then, they will reply with an MSS value which 1391 * will get recorded and the new parameters should get 1392 * recomputed. For Further Study. 1393 */ 1394 if (tp->t_maxopd <= mss) 1395 return inp; 1396 tp->t_maxopd = mss; 1397 1398 if ((tp->t_flags & (TF_REQ_TSTMP|TF_NOOPT)) == TF_REQ_TSTMP && 1399 (tp->t_flags & TF_RCVD_TSTMP) == TF_RCVD_TSTMP) 1400 mss -= TCPOLEN_TSTAMP_APPA; 1401 if ((tp->t_flags & (TF_REQ_CC|TF_NOOPT)) == TF_REQ_CC && 1402 (tp->t_flags & TF_RCVD_CC) == TF_RCVD_CC) 1403 mss -= TCPOLEN_CC_APPA; 1404#if (MCLBYTES & (MCLBYTES - 1)) == 0 1405 if (mss > MCLBYTES) 1406 mss &= ~(MCLBYTES-1); 1407#else 1408 if (mss > MCLBYTES) 1409 mss = mss / MCLBYTES * MCLBYTES; 1410#endif 1411 if (so->so_snd.sb_hiwat < mss) 1412 mss = so->so_snd.sb_hiwat; 1413 1414 tp->t_maxseg = mss; 1415 1416 tcpstat.tcps_mturesent++; 1417 tp->t_rtttime = 0; 1418 tp->snd_nxt = tp->snd_una; 1419 tcp_output(tp); 1420 } 1421 return inp; 1422} 1423 1424/* 1425 * Look-up the routing entry to the peer of this inpcb. If no route 1426 * is found and it cannot be allocated, then return NULL. This routine 1427 * is called by TCP routines that access the rmx structure and by tcp_mss 1428 * to get the interface MTU. 1429 */ 1430u_long 1431tcp_maxmtu(inc) 1432 struct in_conninfo *inc; 1433{ 1434 struct route sro; 1435 struct sockaddr_in *dst; 1436 struct ifnet *ifp; 1437 u_long maxmtu = 0; 1438 1439 KASSERT(inc != NULL, ("tcp_maxmtu with NULL in_conninfo pointer")); 1440 1441 bzero(&sro, sizeof(sro)); 1442 if (inc->inc_faddr.s_addr != INADDR_ANY) { 1443 dst = (struct sockaddr_in *)&sro.ro_dst; 1444 dst->sin_family = AF_INET; 1445 dst->sin_len = sizeof(*dst); 1446 dst->sin_addr = inc->inc_faddr; 1447 rtalloc_ign(&sro, RTF_CLONING); 1448 } 1449 if (sro.ro_rt != NULL) { 1450 ifp = sro.ro_rt->rt_ifp; 1451 if (sro.ro_rt->rt_rmx.rmx_mtu == 0) 1452 maxmtu = ifp->if_mtu; 1453 else 1454 maxmtu = min(sro.ro_rt->rt_rmx.rmx_mtu, ifp->if_mtu); 1455 RTFREE(sro.ro_rt); 1456 } 1457 return (maxmtu); 1458} 1459 1460#ifdef INET6 1461u_long 1462tcp_maxmtu6(inc) 1463 struct in_conninfo *inc; 1464{ 1465 struct route_in6 sro6; 1466 struct ifnet *ifp; 1467 u_long maxmtu = 0; 1468 1469 KASSERT(inc != NULL, ("tcp_maxmtu6 with NULL in_conninfo pointer")); 1470 1471 bzero(&sro6, sizeof(sro6)); 1472 if (!IN6_IS_ADDR_UNSPECIFIED(&inc->inc6_faddr)) { 1473 sro6.ro_dst.sin6_family = AF_INET6; 1474 sro6.ro_dst.sin6_len = sizeof(struct sockaddr_in6); 1475 sro6.ro_dst.sin6_addr = inc->inc6_faddr; 1476 rtalloc_ign((struct route *)&sro6, RTF_CLONING); 1477 } 1478 if (sro6.ro_rt != NULL) { 1479 ifp = sro6.ro_rt->rt_ifp; 1480 if (sro6.ro_rt->rt_rmx.rmx_mtu == 0) 1481 maxmtu = IN6_LINKMTU(sro6.ro_rt->rt_ifp); 1482 else 1483 maxmtu = min(sro6.ro_rt->rt_rmx.rmx_mtu, 1484 IN6_LINKMTU(sro6.ro_rt->rt_ifp)); 1485 RTFREE(sro6.ro_rt); 1486 } 1487 1488 return (maxmtu); 1489} 1490#endif /* INET6 */ 1491 1492#ifdef IPSEC 1493/* compute ESP/AH header size for TCP, including outer IP header. */ 1494size_t 1495ipsec_hdrsiz_tcp(tp) 1496 struct tcpcb *tp; 1497{ 1498 struct inpcb *inp; 1499 struct mbuf *m; 1500 size_t hdrsiz; 1501 struct ip *ip; 1502#ifdef INET6 1503 struct ip6_hdr *ip6; 1504#endif 1505 struct tcphdr *th; 1506 1507 if ((tp == NULL) || ((inp = tp->t_inpcb) == NULL)) 1508 return 0; 1509 MGETHDR(m, M_DONTWAIT, MT_DATA); 1510 if (!m) 1511 return 0; 1512 1513#ifdef INET6 1514 if ((inp->inp_vflag & INP_IPV6) != 0) { 1515 ip6 = mtod(m, struct ip6_hdr *); 1516 th = (struct tcphdr *)(ip6 + 1); 1517 m->m_pkthdr.len = m->m_len = 1518 sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 1519 tcpip_fillheaders(inp, ip6, th); 1520 hdrsiz = ipsec6_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp); 1521 } else 1522#endif /* INET6 */ 1523 { 1524 ip = mtod(m, struct ip *); 1525 th = (struct tcphdr *)(ip + 1); 1526 m->m_pkthdr.len = m->m_len = sizeof(struct tcpiphdr); 1527 tcpip_fillheaders(inp, ip, th); 1528 hdrsiz = ipsec4_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp); 1529 } 1530 1531 m_free(m); 1532 return hdrsiz; 1533} 1534#endif /*IPSEC*/ 1535 1536/* 1537 * Move a TCP connection into TIME_WAIT state. 1538 * tcbinfo is unlocked. 1539 * inp is locked, and is unlocked before returning. 1540 */ 1541void 1542tcp_twstart(tp) 1543 struct tcpcb *tp; 1544{ 1545 struct tcptw *tw; 1546 struct inpcb *inp; 1547 int tw_time, acknow; 1548 struct socket *so; 1549 1550 tw = uma_zalloc(tcptw_zone, M_NOWAIT); 1551 if (tw == NULL) { 1552 tw = tcp_timer_2msl_tw(1); 1553 if (tw == NULL) { 1554 tcp_close(tp); 1555 return; 1556 } 1557 } 1558 inp = tp->t_inpcb; 1559 tw->tw_inpcb = inp; 1560 1561 /* 1562 * Recover last window size sent. 1563 */ 1564 tw->last_win = (tp->rcv_adv - tp->rcv_nxt) >> tp->rcv_scale; 1565 1566 /* 1567 * Set t_recent if timestamps are used on the connection. 1568 */ 1569 if ((tp->t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP|TF_NOOPT)) == 1570 (TF_REQ_TSTMP|TF_RCVD_TSTMP)) 1571 tw->t_recent = tp->ts_recent; 1572 else 1573 tw->t_recent = 0; 1574 1575 tw->snd_nxt = tp->snd_nxt; 1576 tw->rcv_nxt = tp->rcv_nxt; 1577 tw->iss = tp->iss; 1578 tw->irs = tp->irs; 1579 tw->cc_recv = tp->cc_recv; 1580 tw->cc_send = tp->cc_send; 1581 tw->t_starttime = tp->t_starttime; 1582 tw->tw_time = 0; 1583 1584/* XXX 1585 * If this code will 1586 * be used for fin-wait-2 state also, then we may need 1587 * a ts_recent from the last segment. 1588 */ 1589 /* Shorten TIME_WAIT [RFC-1644, p.28] */ 1590 if (tp->cc_recv != 0 && (ticks - tp->t_starttime) < tcp_msl) { 1591 tw_time = tp->t_rxtcur * TCPTV_TWTRUNC; 1592 /* For T/TCP client, force ACK now. */ 1593 acknow = 1; 1594 } else { 1595 tw_time = 2 * tcp_msl; 1596 acknow = tp->t_flags & TF_ACKNOW; 1597 } 1598 tcp_discardcb(tp); 1599 so = inp->inp_socket; 1600 so->so_pcb = NULL; 1601 tw->tw_cred = crhold(so->so_cred); 1602 tw->tw_so_options = so->so_options; 1603 if (acknow) 1604 tcp_twrespond(tw, so, NULL, TH_ACK); 1605 sotryfree(so); 1606 inp->inp_socket = NULL; 1607 inp->inp_ppcb = (caddr_t)tw; 1608 inp->inp_vflag |= INP_TIMEWAIT; 1609 tcp_timer_2msl_reset(tw, tw_time); 1610 INP_UNLOCK(inp); 1611} 1612 1613/* 1614 * The appromixate rate of ISN increase of Microsoft TCP stacks; 1615 * the actual rate is slightly higher due to the addition of 1616 * random positive increments. 1617 * 1618 * Most other new OSes use semi-randomized ISN values, so we 1619 * do not need to worry about them. 1620 */ 1621#define MS_ISN_BYTES_PER_SECOND 250000 1622 1623/* 1624 * Determine if the ISN we will generate has advanced beyond the last 1625 * sequence number used by the previous connection. If so, indicate 1626 * that it is safe to recycle this tw socket by returning 1. 1627 */ 1628int 1629tcp_twrecycleable(struct tcptw *tw) 1630{ 1631 tcp_seq new_iss = tw->iss; 1632 tcp_seq new_irs = tw->irs; 1633 1634 new_iss += (ticks - tw->t_starttime) * (ISN_BYTES_PER_SECOND / hz); 1635 new_irs += (ticks - tw->t_starttime) * (MS_ISN_BYTES_PER_SECOND / hz); 1636 1637 if (SEQ_GT(new_iss, tw->snd_nxt) && SEQ_GT(new_irs, tw->rcv_nxt)) 1638 return 1; 1639 else 1640 return 0; 1641} 1642 1643struct tcptw * 1644tcp_twclose(struct tcptw *tw, int reuse) 1645{ 1646 struct inpcb *inp; 1647 1648 inp = tw->tw_inpcb; 1649 tw->tw_inpcb = NULL; 1650 tcp_timer_2msl_stop(tw); 1651 inp->inp_ppcb = NULL; 1652#ifdef INET6 1653 if (inp->inp_vflag & INP_IPV6PROTO) 1654 in6_pcbdetach(inp); 1655 else 1656#endif 1657 in_pcbdetach(inp); 1658 tcpstat.tcps_closed++; 1659 if (reuse) 1660 return (tw); 1661 uma_zfree(tcptw_zone, tw); 1662 return (NULL); 1663} 1664 1665/* 1666 * One of so and msrc must be non-NULL for use by the MAC Framework to 1667 * construct a label for ay resulting packet. 1668 */ 1669int 1670tcp_twrespond(struct tcptw *tw, struct socket *so, struct mbuf *msrc, 1671 int flags) 1672{ 1673 struct inpcb *inp = tw->tw_inpcb; 1674 struct tcphdr *th; 1675 struct mbuf *m; 1676 struct ip *ip = NULL; 1677 u_int8_t *optp; 1678 u_int hdrlen, optlen; 1679 int error; 1680#ifdef INET6 1681 struct ip6_hdr *ip6 = NULL; 1682 int isipv6 = inp->inp_inc.inc_isipv6; 1683#endif 1684 1685 KASSERT(so != NULL || msrc != NULL, 1686 ("tcp_twrespond: so and msrc NULL")); 1687 1688 m = m_gethdr(M_DONTWAIT, MT_HEADER); 1689 if (m == NULL) 1690 return (ENOBUFS); 1691 m->m_data += max_linkhdr; 1692 1693#ifdef MAC 1694 mac_create_mbuf_from_inpcb(inp, m); 1695#endif 1696 1697#ifdef INET6 1698 if (isipv6) { 1699 hdrlen = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 1700 ip6 = mtod(m, struct ip6_hdr *); 1701 th = (struct tcphdr *)(ip6 + 1); 1702 tcpip_fillheaders(inp, ip6, th); 1703 } else 1704#endif 1705 { 1706 hdrlen = sizeof(struct tcpiphdr); 1707 ip = mtod(m, struct ip *); 1708 th = (struct tcphdr *)(ip + 1); 1709 tcpip_fillheaders(inp, ip, th); 1710 } 1711 optp = (u_int8_t *)(th + 1); 1712 1713 /* 1714 * Send a timestamp and echo-reply if both our side and our peer 1715 * have sent timestamps in our SYN's and this is not a RST. 1716 */ 1717 if (tw->t_recent && flags == TH_ACK) { 1718 u_int32_t *lp = (u_int32_t *)optp; 1719 1720 /* Form timestamp option as shown in appendix A of RFC 1323. */ 1721 *lp++ = htonl(TCPOPT_TSTAMP_HDR); 1722 *lp++ = htonl(ticks); 1723 *lp = htonl(tw->t_recent); 1724 optp += TCPOLEN_TSTAMP_APPA; 1725 } 1726 1727 /* 1728 * Send `CC-family' options if needed, and it's not a RST. 1729 */ 1730 if (tw->cc_recv != 0 && flags == TH_ACK) { 1731 u_int32_t *lp = (u_int32_t *)optp; 1732 1733 *lp++ = htonl(TCPOPT_CC_HDR(TCPOPT_CC)); 1734 *lp = htonl(tw->cc_send); 1735 optp += TCPOLEN_CC_APPA; 1736 } 1737 optlen = optp - (u_int8_t *)(th + 1); 1738 1739 m->m_len = hdrlen + optlen; 1740 m->m_pkthdr.len = m->m_len; 1741 1742 KASSERT(max_linkhdr + m->m_len <= MHLEN, ("tcptw: mbuf too small")); 1743 1744 th->th_seq = htonl(tw->snd_nxt); 1745 th->th_ack = htonl(tw->rcv_nxt); 1746 th->th_off = (sizeof(struct tcphdr) + optlen) >> 2; 1747 th->th_flags = flags; 1748 th->th_win = htons(tw->last_win); 1749 1750#ifdef INET6 1751 if (isipv6) { 1752 th->th_sum = in6_cksum(m, IPPROTO_TCP, sizeof(struct ip6_hdr), 1753 sizeof(struct tcphdr) + optlen); 1754 ip6->ip6_hlim = in6_selecthlim(inp, NULL); 1755 error = ip6_output(m, inp->in6p_outputopts, NULL, 1756 (tw->tw_so_options & SO_DONTROUTE), NULL, NULL, inp); 1757 } else 1758#endif 1759 { 1760 th->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr, 1761 htons(sizeof(struct tcphdr) + optlen + IPPROTO_TCP)); 1762 m->m_pkthdr.csum_flags = CSUM_TCP; 1763 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 1764 ip->ip_len = m->m_pkthdr.len; 1765 if (path_mtu_discovery) 1766 ip->ip_off |= IP_DF; 1767 error = ip_output(m, inp->inp_options, NULL, 1768 (tw->tw_so_options & SO_DONTROUTE), NULL, inp); 1769 } 1770 if (flags & TH_ACK) 1771 tcpstat.tcps_sndacks++; 1772 else 1773 tcpstat.tcps_sndctrl++; 1774 tcpstat.tcps_sndtotal++; 1775 return (error); 1776} 1777 1778/* 1779 * TCP BANDWIDTH DELAY PRODUCT WINDOW LIMITING 1780 * 1781 * This code attempts to calculate the bandwidth-delay product as a 1782 * means of determining the optimal window size to maximize bandwidth, 1783 * minimize RTT, and avoid the over-allocation of buffers on interfaces and 1784 * routers. This code also does a fairly good job keeping RTTs in check 1785 * across slow links like modems. We implement an algorithm which is very 1786 * similar (but not meant to be) TCP/Vegas. The code operates on the 1787 * transmitter side of a TCP connection and so only effects the transmit 1788 * side of the connection. 1789 * 1790 * BACKGROUND: TCP makes no provision for the management of buffer space 1791 * at the end points or at the intermediate routers and switches. A TCP 1792 * stream, whether using NewReno or not, will eventually buffer as 1793 * many packets as it is able and the only reason this typically works is 1794 * due to the fairly small default buffers made available for a connection 1795 * (typicaly 16K or 32K). As machines use larger windows and/or window 1796 * scaling it is now fairly easy for even a single TCP connection to blow-out 1797 * all available buffer space not only on the local interface, but on 1798 * intermediate routers and switches as well. NewReno makes a misguided 1799 * attempt to 'solve' this problem by waiting for an actual failure to occur, 1800 * then backing off, then steadily increasing the window again until another 1801 * failure occurs, ad-infinitum. This results in terrible oscillation that 1802 * is only made worse as network loads increase and the idea of intentionally 1803 * blowing out network buffers is, frankly, a terrible way to manage network 1804 * resources. 1805 * 1806 * It is far better to limit the transmit window prior to the failure 1807 * condition being achieved. There are two general ways to do this: First 1808 * you can 'scan' through different transmit window sizes and locate the 1809 * point where the RTT stops increasing, indicating that you have filled the 1810 * pipe, then scan backwards until you note that RTT stops decreasing, then 1811 * repeat ad-infinitum. This method works in principle but has severe 1812 * implementation issues due to RTT variances, timer granularity, and 1813 * instability in the algorithm which can lead to many false positives and 1814 * create oscillations as well as interact badly with other TCP streams 1815 * implementing the same algorithm. 1816 * 1817 * The second method is to limit the window to the bandwidth delay product 1818 * of the link. This is the method we implement. RTT variances and our 1819 * own manipulation of the congestion window, bwnd, can potentially 1820 * destabilize the algorithm. For this reason we have to stabilize the 1821 * elements used to calculate the window. We do this by using the minimum 1822 * observed RTT, the long term average of the observed bandwidth, and 1823 * by adding two segments worth of slop. It isn't perfect but it is able 1824 * to react to changing conditions and gives us a very stable basis on 1825 * which to extend the algorithm. 1826 */ 1827void 1828tcp_xmit_bandwidth_limit(struct tcpcb *tp, tcp_seq ack_seq) 1829{ 1830 u_long bw; 1831 u_long bwnd; 1832 int save_ticks; 1833 1834 /* 1835 * If inflight_enable is disabled in the middle of a tcp connection, 1836 * make sure snd_bwnd is effectively disabled. 1837 */ 1838 if (tcp_inflight_enable == 0) { 1839 tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 1840 tp->snd_bandwidth = 0; 1841 return; 1842 } 1843 1844 /* 1845 * Figure out the bandwidth. Due to the tick granularity this 1846 * is a very rough number and it MUST be averaged over a fairly 1847 * long period of time. XXX we need to take into account a link 1848 * that is not using all available bandwidth, but for now our 1849 * slop will ramp us up if this case occurs and the bandwidth later 1850 * increases. 1851 * 1852 * Note: if ticks rollover 'bw' may wind up negative. We must 1853 * effectively reset t_bw_rtttime for this case. 1854 */ 1855 save_ticks = ticks; 1856 if ((u_int)(save_ticks - tp->t_bw_rtttime) < 1) 1857 return; 1858 1859 bw = (int64_t)(ack_seq - tp->t_bw_rtseq) * hz / 1860 (save_ticks - tp->t_bw_rtttime); 1861 tp->t_bw_rtttime = save_ticks; 1862 tp->t_bw_rtseq = ack_seq; 1863 if (tp->t_bw_rtttime == 0 || (int)bw < 0) 1864 return; 1865 bw = ((int64_t)tp->snd_bandwidth * 15 + bw) >> 4; 1866 1867 tp->snd_bandwidth = bw; 1868 1869 /* 1870 * Calculate the semi-static bandwidth delay product, plus two maximal 1871 * segments. The additional slop puts us squarely in the sweet 1872 * spot and also handles the bandwidth run-up case and stabilization. 1873 * Without the slop we could be locking ourselves into a lower 1874 * bandwidth. 1875 * 1876 * Situations Handled: 1877 * (1) Prevents over-queueing of packets on LANs, especially on 1878 * high speed LANs, allowing larger TCP buffers to be 1879 * specified, and also does a good job preventing 1880 * over-queueing of packets over choke points like modems 1881 * (at least for the transmit side). 1882 * 1883 * (2) Is able to handle changing network loads (bandwidth 1884 * drops so bwnd drops, bandwidth increases so bwnd 1885 * increases). 1886 * 1887 * (3) Theoretically should stabilize in the face of multiple 1888 * connections implementing the same algorithm (this may need 1889 * a little work). 1890 * 1891 * (4) Stability value (defaults to 20 = 2 maximal packets) can 1892 * be adjusted with a sysctl but typically only needs to be 1893 * on very slow connections. A value no smaller then 5 1894 * should be used, but only reduce this default if you have 1895 * no other choice. 1896 */ 1897#define USERTT ((tp->t_srtt + tp->t_rttbest) / 2) 1898 bwnd = (int64_t)bw * USERTT / (hz << TCP_RTT_SHIFT) + tcp_inflight_stab * tp->t_maxseg / 10; 1899#undef USERTT 1900 1901 if (tcp_inflight_debug > 0) { 1902 static int ltime; 1903 if ((u_int)(ticks - ltime) >= hz / tcp_inflight_debug) { 1904 ltime = ticks; 1905 printf("%p bw %ld rttbest %d srtt %d bwnd %ld\n", 1906 tp, 1907 bw, 1908 tp->t_rttbest, 1909 tp->t_srtt, 1910 bwnd 1911 ); 1912 } 1913 } 1914 if ((long)bwnd < tcp_inflight_min) 1915 bwnd = tcp_inflight_min; 1916 if (bwnd > tcp_inflight_max) 1917 bwnd = tcp_inflight_max; 1918 if ((long)bwnd < tp->t_maxseg * 2) 1919 bwnd = tp->t_maxseg * 2; 1920 tp->snd_bwnd = bwnd; 1921} 1922 1923#ifdef TCP_SIGNATURE 1924/* 1925 * Callback function invoked by m_apply() to digest TCP segment data 1926 * contained within an mbuf chain. 1927 */ 1928static int 1929tcp_signature_apply(void *fstate, void *data, u_int len) 1930{ 1931 1932 MD5Update(fstate, (u_char *)data, len); 1933 return (0); 1934} 1935 1936/* 1937 * Compute TCP-MD5 hash of a TCPv4 segment. (RFC2385) 1938 * 1939 * Parameters: 1940 * m pointer to head of mbuf chain 1941 * off0 offset to TCP header within the mbuf chain 1942 * len length of TCP segment data, excluding options 1943 * optlen length of TCP segment options 1944 * buf pointer to storage for computed MD5 digest 1945 * direction direction of flow (IPSEC_DIR_INBOUND or OUTBOUND) 1946 * 1947 * We do this over ip, tcphdr, segment data, and the key in the SADB. 1948 * When called from tcp_input(), we can be sure that th_sum has been 1949 * zeroed out and verified already. 1950 * 1951 * This function is for IPv4 use only. Calling this function with an 1952 * IPv6 packet in the mbuf chain will yield undefined results. 1953 * 1954 * Return 0 if successful, otherwise return -1. 1955 * 1956 * XXX The key is retrieved from the system's PF_KEY SADB, by keying a 1957 * search with the destination IP address, and a 'magic SPI' to be 1958 * determined by the application. This is hardcoded elsewhere to 1179 1959 * right now. Another branch of this code exists which uses the SPD to 1960 * specify per-application flows but it is unstable. 1961 */ 1962int 1963tcp_signature_compute(struct mbuf *m, int off0, int len, int optlen, 1964 u_char *buf, u_int direction) 1965{ 1966 union sockaddr_union dst; 1967 struct ippseudo ippseudo; 1968 MD5_CTX ctx; 1969 int doff; 1970 struct ip *ip; 1971 struct ipovly *ipovly; 1972 struct secasvar *sav; 1973 struct tcphdr *th; 1974 u_short savecsum; 1975 1976 KASSERT(m != NULL, ("NULL mbuf chain")); 1977 KASSERT(buf != NULL, ("NULL signature pointer")); 1978 1979 /* Extract the destination from the IP header in the mbuf. */ 1980 ip = mtod(m, struct ip *); 1981 bzero(&dst, sizeof(union sockaddr_union)); 1982 dst.sa.sa_len = sizeof(struct sockaddr_in); 1983 dst.sa.sa_family = AF_INET; 1984 dst.sin.sin_addr = (direction == IPSEC_DIR_INBOUND) ? 1985 ip->ip_src : ip->ip_dst; 1986 1987 /* Look up an SADB entry which matches the address of the peer. */ 1988 sav = KEY_ALLOCSA(&dst, IPPROTO_TCP, htonl(TCP_SIG_SPI)); 1989 if (sav == NULL) { 1990 printf("%s: SADB lookup failed for %s\n", __func__, 1991 inet_ntoa(dst.sin.sin_addr)); 1992 return (EINVAL); 1993 } 1994 1995 MD5Init(&ctx); 1996 ipovly = (struct ipovly *)ip; 1997 th = (struct tcphdr *)((u_char *)ip + off0); 1998 doff = off0 + sizeof(struct tcphdr) + optlen; 1999 2000 /* 2001 * Step 1: Update MD5 hash with IP pseudo-header. 2002 * 2003 * XXX The ippseudo header MUST be digested in network byte order, 2004 * or else we'll fail the regression test. Assume all fields we've 2005 * been doing arithmetic on have been in host byte order. 2006 * XXX One cannot depend on ipovly->ih_len here. When called from 2007 * tcp_output(), the underlying ip_len member has not yet been set. 2008 */ 2009 ippseudo.ippseudo_src = ipovly->ih_src; 2010 ippseudo.ippseudo_dst = ipovly->ih_dst; 2011 ippseudo.ippseudo_pad = 0; 2012 ippseudo.ippseudo_p = IPPROTO_TCP; 2013 ippseudo.ippseudo_len = htons(len + sizeof(struct tcphdr) + optlen); 2014 MD5Update(&ctx, (char *)&ippseudo, sizeof(struct ippseudo)); 2015 2016 /* 2017 * Step 2: Update MD5 hash with TCP header, excluding options. 2018 * The TCP checksum must be set to zero. 2019 */ 2020 savecsum = th->th_sum; 2021 th->th_sum = 0; 2022 MD5Update(&ctx, (char *)th, sizeof(struct tcphdr)); 2023 th->th_sum = savecsum; 2024 2025 /* 2026 * Step 3: Update MD5 hash with TCP segment data. 2027 * Use m_apply() to avoid an early m_pullup(). 2028 */ 2029 if (len > 0) 2030 m_apply(m, doff, len, tcp_signature_apply, &ctx); 2031 2032 /* 2033 * Step 4: Update MD5 hash with shared secret. 2034 */ 2035 MD5Update(&ctx, _KEYBUF(sav->key_auth), _KEYLEN(sav->key_auth)); 2036 MD5Final(buf, &ctx); 2037 2038 key_sa_recordxfer(sav, m); 2039 KEY_FREESAV(&sav); 2040 return (0); 2041} 2042#endif /* TCP_SIGNATURE */ 2043