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: src/sys/netinet/tcp_subr.c,v 1.73.2.31 2003/01/24 05:11:34 sam Exp $ 35 * $DragonFly: src/sys/netinet/tcp_subr.c,v 1.33 2004/06/07 02:36:22 dillon Exp $ 36 */ 37 38 #include "opt_compat.h" 39 #include "opt_inet6.h" 40 #include "opt_ipsec.h" 41 #include "opt_tcpdebug.h" 42 43 #include <sys/param.h> 44 #include <sys/systm.h> 45 #include <sys/callout.h> 46 #include <sys/kernel.h> 47 #include <sys/sysctl.h> 48 #include <sys/malloc.h> 49 #include <sys/mpipe.h> 50 #include <sys/mbuf.h> 51 #ifdef INET6 52 #include <sys/domain.h> 53 #endif 54 #include <sys/proc.h> 55 #include <sys/socket.h> 56 #include <sys/socketvar.h> 57 #include <sys/protosw.h> 58 #include <sys/random.h> 59 #include <sys/in_cksum.h> 60 61 #include <vm/vm_zone.h> 62 63 #include <net/route.h> 64 #include <net/if.h> 65 #include <net/netisr.h> 66 67 #define _IP_VHL 68 #include <netinet/in.h> 69 #include <netinet/in_systm.h> 70 #include <netinet/ip.h> 71 #include <netinet/ip6.h> 72 #include <netinet/in_pcb.h> 73 #include <netinet6/in6_pcb.h> 74 #include <netinet/in_var.h> 75 #include <netinet/ip_var.h> 76 #include <netinet6/ip6_var.h> 77 #include <netinet/tcp.h> 78 #include <netinet/tcp_fsm.h> 79 #include <netinet/tcp_seq.h> 80 #include <netinet/tcp_timer.h> 81 #include <netinet/tcp_var.h> 82 #include <netinet6/tcp6_var.h> 83 #include <netinet/tcpip.h> 84 #ifdef TCPDEBUG 85 #include <netinet/tcp_debug.h> 86 #endif 87 #include <netinet6/ip6protosw.h> 88 89 #ifdef IPSEC 90 #include <netinet6/ipsec.h> 91 #ifdef INET6 92 #include <netinet6/ipsec6.h> 93 #endif 94 #endif 95 96 #ifdef FAST_IPSEC 97 #include <netipsec/ipsec.h> 98 #ifdef INET6 99 #include <netipsec/ipsec6.h> 100 #endif 101 #define IPSEC 102 #endif 103 104 #include <sys/md5.h> 105 106 #include <sys/msgport2.h> 107 108 #include <machine/smp.h> 109 110 int tcp_mssdflt = TCP_MSS; 111 SYSCTL_INT(_net_inet_tcp, TCPCTL_MSSDFLT, mssdflt, CTLFLAG_RW, 112 &tcp_mssdflt, 0, "Default TCP Maximum Segment Size"); 113 114 #ifdef INET6 115 int tcp_v6mssdflt = TCP6_MSS; 116 SYSCTL_INT(_net_inet_tcp, TCPCTL_V6MSSDFLT, v6mssdflt, CTLFLAG_RW, 117 &tcp_v6mssdflt, 0, "Default TCP Maximum Segment Size for IPv6"); 118 #endif 119 120 #if 0 121 static int tcp_rttdflt = TCPTV_SRTTDFLT / PR_SLOWHZ; 122 SYSCTL_INT(_net_inet_tcp, TCPCTL_RTTDFLT, rttdflt, CTLFLAG_RW, 123 &tcp_rttdflt, 0, "Default maximum TCP Round Trip Time"); 124 #endif 125 126 int tcp_do_rfc1323 = 1; 127 SYSCTL_INT(_net_inet_tcp, TCPCTL_DO_RFC1323, rfc1323, CTLFLAG_RW, 128 &tcp_do_rfc1323, 0, "Enable rfc1323 (high performance TCP) extensions"); 129 130 int tcp_do_rfc1644 = 0; 131 SYSCTL_INT(_net_inet_tcp, TCPCTL_DO_RFC1644, rfc1644, CTLFLAG_RW, 132 &tcp_do_rfc1644, 0, "Enable rfc1644 (TTCP) extensions"); 133 134 static int tcp_tcbhashsize = 0; 135 SYSCTL_INT(_net_inet_tcp, OID_AUTO, tcbhashsize, CTLFLAG_RD, 136 &tcp_tcbhashsize, 0, "Size of TCP control block hashtable"); 137 138 static int do_tcpdrain = 1; 139 SYSCTL_INT(_net_inet_tcp, OID_AUTO, do_tcpdrain, CTLFLAG_RW, &do_tcpdrain, 0, 140 "Enable tcp_drain routine for extra help when low on mbufs"); 141 142 /* XXX JH */ 143 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pcbcount, CTLFLAG_RD, 144 &tcbinfo[0].ipi_count, 0, "Number of active PCBs"); 145 146 static int icmp_may_rst = 1; 147 SYSCTL_INT(_net_inet_tcp, OID_AUTO, icmp_may_rst, CTLFLAG_RW, &icmp_may_rst, 0, 148 "Certain ICMP unreachable messages may abort connections in SYN_SENT"); 149 150 static int tcp_isn_reseed_interval = 0; 151 SYSCTL_INT(_net_inet_tcp, OID_AUTO, isn_reseed_interval, CTLFLAG_RW, 152 &tcp_isn_reseed_interval, 0, "Seconds between reseeding of ISN secret"); 153 154 /* 155 * TCP bandwidth limiting sysctls. Note that the default lower bound of 156 * 1024 exists only for debugging. A good production default would be 157 * something like 6100. 158 */ 159 static int tcp_inflight_enable = 0; 160 SYSCTL_INT(_net_inet_tcp, OID_AUTO, inflight_enable, CTLFLAG_RW, 161 &tcp_inflight_enable, 0, "Enable automatic TCP inflight data limiting"); 162 163 static int tcp_inflight_debug = 0; 164 SYSCTL_INT(_net_inet_tcp, OID_AUTO, inflight_debug, CTLFLAG_RW, 165 &tcp_inflight_debug, 0, "Debug TCP inflight calculations"); 166 167 static int tcp_inflight_min = 6144; 168 SYSCTL_INT(_net_inet_tcp, OID_AUTO, inflight_min, CTLFLAG_RW, 169 &tcp_inflight_min, 0, "Lower bound for TCP inflight window"); 170 171 static int tcp_inflight_max = TCP_MAXWIN << TCP_MAX_WINSHIFT; 172 SYSCTL_INT(_net_inet_tcp, OID_AUTO, inflight_max, CTLFLAG_RW, 173 &tcp_inflight_max, 0, "Upper bound for TCP inflight window"); 174 175 static int tcp_inflight_stab = 20; 176 SYSCTL_INT(_net_inet_tcp, OID_AUTO, inflight_stab, CTLFLAG_RW, 177 &tcp_inflight_stab, 0, "Slop in maximal packets / 10 (20 = 2 packets)"); 178 179 static MALLOC_DEFINE(M_TCPTEMP, "tcptemp", "TCP Templates for Keepalives"); 180 static struct malloc_pipe tcptemp_mpipe; 181 182 static void tcp_cleartaocache (void); 183 static void tcp_notify (struct inpcb *, int); 184 185 struct tcp_stats tcpstats_ary[MAXCPU]; 186 #ifdef SMP 187 static int 188 sysctl_tcpstats(SYSCTL_HANDLER_ARGS) 189 { 190 int cpu, error = 0; 191 192 for (cpu = 0; cpu < ncpus; ++cpu) { 193 if ((error = SYSCTL_OUT(req, (void *)&tcpstats_ary[cpu], 194 sizeof(struct tcp_stats)))) 195 break; 196 if ((error = SYSCTL_IN(req, (void *)&tcpstats_ary[cpu], 197 sizeof(struct tcp_stats)))) 198 break; 199 } 200 201 return (error); 202 } 203 SYSCTL_PROC(_net_inet_tcp, TCPCTL_STATS, stats, (CTLTYPE_OPAQUE | CTLFLAG_RW), 204 0, 0, sysctl_tcpstats, "S,tcp_stats", "TCP statistics"); 205 #else 206 SYSCTL_STRUCT(_net_inet_tcp, TCPCTL_STATS, stats, CTLFLAG_RW, 207 &tcpstat, tcp_stats, "TCP statistics"); 208 #endif 209 210 /* 211 * Target size of TCP PCB hash tables. Must be a power of two. 212 * 213 * Note that this can be overridden by the kernel environment 214 * variable net.inet.tcp.tcbhashsize 215 */ 216 #ifndef TCBHASHSIZE 217 #define TCBHASHSIZE 512 218 #endif 219 220 /* 221 * This is the actual shape of what we allocate using the zone 222 * allocator. Doing it this way allows us to protect both structures 223 * using the same generation count, and also eliminates the overhead 224 * of allocating tcpcbs separately. By hiding the structure here, 225 * we avoid changing most of the rest of the code (although it needs 226 * to be changed, eventually, for greater efficiency). 227 */ 228 #define ALIGNMENT 32 229 #define ALIGNM1 (ALIGNMENT - 1) 230 struct inp_tp { 231 union { 232 struct inpcb inp; 233 char align[(sizeof(struct inpcb) + ALIGNM1) & ~ALIGNM1]; 234 } inp_tp_u; 235 struct tcpcb tcb; 236 struct callout inp_tp_rexmt, inp_tp_persist, inp_tp_keep, inp_tp_2msl; 237 struct callout inp_tp_delack; 238 }; 239 #undef ALIGNMENT 240 #undef ALIGNM1 241 242 /* 243 * Tcp initialization 244 */ 245 void 246 tcp_init() 247 { 248 struct inpcbporthead *porthashbase; 249 u_long porthashmask; 250 struct vm_zone *ipi_zone; 251 int hashsize = TCBHASHSIZE; 252 int cpu; 253 254 /* 255 * note: tcptemp is used for keepalives, and it is ok for an 256 * allocation to fail so do not specify MPF_INT. 257 */ 258 mpipe_init(&tcptemp_mpipe, M_TCPTEMP, sizeof(struct tcptemp), 259 25, -1, 0, NULL); 260 261 tcp_ccgen = 1; 262 tcp_cleartaocache(); 263 264 tcp_delacktime = TCPTV_DELACK; 265 tcp_keepinit = TCPTV_KEEP_INIT; 266 tcp_keepidle = TCPTV_KEEP_IDLE; 267 tcp_keepintvl = TCPTV_KEEPINTVL; 268 tcp_maxpersistidle = TCPTV_KEEP_IDLE; 269 tcp_msl = TCPTV_MSL; 270 tcp_rexmit_min = TCPTV_MIN; 271 tcp_rexmit_slop = TCPTV_CPU_VAR; 272 273 TUNABLE_INT_FETCH("net.inet.tcp.tcbhashsize", &hashsize); 274 if (!powerof2(hashsize)) { 275 printf("WARNING: TCB hash size not a power of 2\n"); 276 hashsize = 512; /* safe default */ 277 } 278 tcp_tcbhashsize = hashsize; 279 porthashbase = hashinit(hashsize, M_PCB, &porthashmask); 280 ipi_zone = zinit("tcpcb", sizeof(struct inp_tp), maxsockets, 281 ZONE_INTERRUPT, 0); 282 283 for (cpu = 0; cpu < ncpus2; cpu++) { 284 in_pcbinfo_init(&tcbinfo[cpu]); 285 tcbinfo[cpu].hashbase = hashinit(hashsize, M_PCB, 286 &tcbinfo[cpu].hashmask); 287 tcbinfo[cpu].porthashbase = porthashbase; 288 tcbinfo[cpu].porthashmask = porthashmask; 289 tcbinfo[cpu].wildcardhashbase = hashinit(hashsize, M_PCB, 290 &tcbinfo[cpu].wildcardhashmask); 291 tcbinfo[cpu].ipi_zone = ipi_zone; 292 } 293 294 tcp_reass_maxseg = nmbclusters / 16; 295 TUNABLE_INT_FETCH("net.inet.tcp.reass.maxsegments", &tcp_reass_maxseg); 296 297 #ifdef INET6 298 #define TCP_MINPROTOHDR (sizeof(struct ip6_hdr) + sizeof(struct tcphdr)) 299 #else 300 #define TCP_MINPROTOHDR (sizeof(struct tcpiphdr)) 301 #endif 302 if (max_protohdr < TCP_MINPROTOHDR) 303 max_protohdr = TCP_MINPROTOHDR; 304 if (max_linkhdr + TCP_MINPROTOHDR > MHLEN) 305 panic("tcp_init"); 306 #undef TCP_MINPROTOHDR 307 308 /* 309 * Initialize TCP statistics. 310 * 311 * It is layed out as an array which is has one element for UP, 312 * and SMP_MAXCPU elements for SMP. This allows us to retain 313 * the access mechanism from userland for both UP and SMP. 314 */ 315 #ifdef SMP 316 for (cpu = 0; cpu < ncpus; ++cpu) { 317 bzero(&tcpstats_ary[cpu], sizeof(struct tcp_stats)); 318 } 319 #else 320 bzero(&tcpstat, sizeof(struct tcp_stats)); 321 #endif 322 323 syncache_init(); 324 tcp_thread_init(); 325 } 326 327 /* 328 * Fill in the IP and TCP headers for an outgoing packet, given the tcpcb. 329 * tcp_template used to store this data in mbufs, but we now recopy it out 330 * of the tcpcb each time to conserve mbufs. 331 */ 332 void 333 tcp_fillheaders(struct tcpcb *tp, void *ip_ptr, void *tcp_ptr) 334 { 335 struct inpcb *inp = tp->t_inpcb; 336 struct tcphdr *tcp_hdr = (struct tcphdr *)tcp_ptr; 337 338 #ifdef INET6 339 if (inp->inp_vflag & INP_IPV6) { 340 struct ip6_hdr *ip6; 341 342 ip6 = (struct ip6_hdr *)ip_ptr; 343 ip6->ip6_flow = (ip6->ip6_flow & ~IPV6_FLOWINFO_MASK) | 344 (inp->in6p_flowinfo & IPV6_FLOWINFO_MASK); 345 ip6->ip6_vfc = (ip6->ip6_vfc & ~IPV6_VERSION_MASK) | 346 (IPV6_VERSION & IPV6_VERSION_MASK); 347 ip6->ip6_nxt = IPPROTO_TCP; 348 ip6->ip6_plen = sizeof(struct tcphdr); 349 ip6->ip6_src = inp->in6p_laddr; 350 ip6->ip6_dst = inp->in6p_faddr; 351 tcp_hdr->th_sum = 0; 352 } else 353 #endif 354 { 355 struct ip *ip = (struct ip *) ip_ptr; 356 357 ip->ip_vhl = IP_VHL_BORING; 358 ip->ip_tos = 0; 359 ip->ip_len = 0; 360 ip->ip_id = 0; 361 ip->ip_off = 0; 362 ip->ip_ttl = 0; 363 ip->ip_sum = 0; 364 ip->ip_p = IPPROTO_TCP; 365 ip->ip_src = inp->inp_laddr; 366 ip->ip_dst = inp->inp_faddr; 367 tcp_hdr->th_sum = in_pseudo(ip->ip_src.s_addr, 368 ip->ip_dst.s_addr, 369 htons(sizeof(struct tcphdr) + IPPROTO_TCP)); 370 } 371 372 tcp_hdr->th_sport = inp->inp_lport; 373 tcp_hdr->th_dport = inp->inp_fport; 374 tcp_hdr->th_seq = 0; 375 tcp_hdr->th_ack = 0; 376 tcp_hdr->th_x2 = 0; 377 tcp_hdr->th_off = 5; 378 tcp_hdr->th_flags = 0; 379 tcp_hdr->th_win = 0; 380 tcp_hdr->th_urp = 0; 381 } 382 383 /* 384 * Create template to be used to send tcp packets on a connection. 385 * Allocates an mbuf and fills in a skeletal tcp/ip header. The only 386 * use for this function is in keepalives, which use tcp_respond. 387 */ 388 struct tcptemp * 389 tcp_maketemplate(struct tcpcb *tp) 390 { 391 struct tcptemp *tmp; 392 393 if ((tmp = mpipe_alloc_nowait(&tcptemp_mpipe)) == NULL) 394 return (NULL); 395 tcp_fillheaders(tp, (void *)&tmp->tt_ipgen, (void *)&tmp->tt_t); 396 return (tmp); 397 } 398 399 void 400 tcp_freetemplate(struct tcptemp *tmp) 401 { 402 mpipe_free(&tcptemp_mpipe, tmp); 403 } 404 405 /* 406 * Send a single message to the TCP at address specified by 407 * the given TCP/IP header. If m == NULL, then we make a copy 408 * of the tcpiphdr at ti and send directly to the addressed host. 409 * This is used to force keep alive messages out using the TCP 410 * template for a connection. If flags are given then we send 411 * a message back to the TCP which originated the * segment ti, 412 * and discard the mbuf containing it and any other attached mbufs. 413 * 414 * In any case the ack and sequence number of the transmitted 415 * segment are as specified by the parameters. 416 * 417 * NOTE: If m != NULL, then ti must point to *inside* the mbuf. 418 */ 419 void 420 tcp_respond(struct tcpcb *tp, void *ipgen, struct tcphdr *th, struct mbuf *m, 421 tcp_seq ack, tcp_seq seq, int flags) 422 { 423 int tlen; 424 int win = 0; 425 struct route *ro = NULL; 426 struct route sro; 427 struct ip *ip = ipgen; 428 struct tcphdr *nth; 429 int ipflags = 0; 430 struct route_in6 *ro6 = NULL; 431 struct route_in6 sro6; 432 struct ip6_hdr *ip6 = ipgen; 433 #ifdef INET6 434 boolean_t isipv6 = (IP_VHL_V(ip->ip_vhl) == 6); 435 #else 436 const boolean_t isipv6 = FALSE; 437 #endif 438 439 if (tp != NULL) { 440 if (!(flags & TH_RST)) { 441 win = sbspace(&tp->t_inpcb->inp_socket->so_rcv); 442 if (win > (long)TCP_MAXWIN << tp->rcv_scale) 443 win = (long)TCP_MAXWIN << tp->rcv_scale; 444 } 445 if (isipv6) 446 ro6 = &tp->t_inpcb->in6p_route; 447 else 448 ro = &tp->t_inpcb->inp_route; 449 } else { 450 if (isipv6) { 451 ro6 = &sro6; 452 bzero(ro6, sizeof *ro6); 453 } else { 454 ro = &sro; 455 bzero(ro, sizeof *ro); 456 } 457 } 458 if (m == NULL) { 459 m = m_gethdr(MB_DONTWAIT, MT_HEADER); 460 if (m == NULL) 461 return; 462 tlen = 0; 463 m->m_data += max_linkhdr; 464 if (isipv6) { 465 bcopy(ip6, mtod(m, caddr_t), sizeof(struct ip6_hdr)); 466 ip6 = mtod(m, struct ip6_hdr *); 467 nth = (struct tcphdr *)(ip6 + 1); 468 } else { 469 bcopy(ip, mtod(m, caddr_t), sizeof(struct ip)); 470 ip = mtod(m, struct ip *); 471 nth = (struct tcphdr *)(ip + 1); 472 } 473 bcopy(th, nth, sizeof(struct tcphdr)); 474 flags = TH_ACK; 475 } else { 476 m_freem(m->m_next); 477 m->m_next = NULL; 478 m->m_data = (caddr_t)ipgen; 479 /* m_len is set later */ 480 tlen = 0; 481 #define xchg(a, b, type) { type t; t = a; a = b; b = t; } 482 if (isipv6) { 483 xchg(ip6->ip6_dst, ip6->ip6_src, struct in6_addr); 484 nth = (struct tcphdr *)(ip6 + 1); 485 } else { 486 xchg(ip->ip_dst.s_addr, ip->ip_src.s_addr, n_long); 487 nth = (struct tcphdr *)(ip + 1); 488 } 489 if (th != nth) { 490 /* 491 * this is usually a case when an extension header 492 * exists between the IPv6 header and the 493 * TCP header. 494 */ 495 nth->th_sport = th->th_sport; 496 nth->th_dport = th->th_dport; 497 } 498 xchg(nth->th_dport, nth->th_sport, n_short); 499 #undef xchg 500 } 501 if (isipv6) { 502 ip6->ip6_flow = 0; 503 ip6->ip6_vfc = IPV6_VERSION; 504 ip6->ip6_nxt = IPPROTO_TCP; 505 ip6->ip6_plen = htons((u_short)(sizeof(struct tcphdr) + tlen)); 506 tlen += sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 507 } else { 508 tlen += sizeof(struct tcpiphdr); 509 ip->ip_len = tlen; 510 ip->ip_ttl = ip_defttl; 511 } 512 m->m_len = tlen; 513 m->m_pkthdr.len = tlen; 514 m->m_pkthdr.rcvif = (struct ifnet *) NULL; 515 nth->th_seq = htonl(seq); 516 nth->th_ack = htonl(ack); 517 nth->th_x2 = 0; 518 nth->th_off = sizeof(struct tcphdr) >> 2; 519 nth->th_flags = flags; 520 if (tp != NULL) 521 nth->th_win = htons((u_short) (win >> tp->rcv_scale)); 522 else 523 nth->th_win = htons((u_short)win); 524 nth->th_urp = 0; 525 if (isipv6) { 526 nth->th_sum = 0; 527 nth->th_sum = in6_cksum(m, IPPROTO_TCP, 528 sizeof(struct ip6_hdr), 529 tlen - sizeof(struct ip6_hdr)); 530 ip6->ip6_hlim = in6_selecthlim(tp ? tp->t_inpcb : NULL, 531 (ro6 && ro6->ro_rt) ? 532 ro6->ro_rt->rt_ifp : NULL); 533 } else { 534 nth->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr, 535 htons((u_short)(tlen - sizeof(struct ip) + ip->ip_p))); 536 m->m_pkthdr.csum_flags = CSUM_TCP; 537 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 538 } 539 #ifdef TCPDEBUG 540 if (tp == NULL || (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) 541 tcp_trace(TA_OUTPUT, 0, tp, mtod(m, void *), th, 0); 542 #endif 543 if (isipv6) { 544 (void)ip6_output(m, NULL, ro6, ipflags, NULL, NULL, 545 tp ? tp->t_inpcb : NULL); 546 if ((ro6 == &sro6) && (ro6->ro_rt != NULL)) { 547 RTFREE(ro6->ro_rt); 548 ro6->ro_rt = NULL; 549 } 550 } else { 551 (void)ip_output(m, NULL, ro, ipflags, NULL, 552 tp ? tp->t_inpcb : NULL); 553 if ((ro == &sro) && (ro->ro_rt != NULL)) { 554 RTFREE(ro->ro_rt); 555 ro->ro_rt = NULL; 556 } 557 } 558 } 559 560 /* 561 * Create a new TCP control block, making an 562 * empty reassembly queue and hooking it to the argument 563 * protocol control block. The `inp' parameter must have 564 * come from the zone allocator set up in tcp_init(). 565 */ 566 struct tcpcb * 567 tcp_newtcpcb(struct inpcb *inp) 568 { 569 struct inp_tp *it; 570 struct tcpcb *tp; 571 #ifdef INET6 572 boolean_t isipv6 = ((inp->inp_vflag & INP_IPV6) != 0); 573 #else 574 const boolean_t isipv6 = FALSE; 575 #endif 576 577 it = (struct inp_tp *)inp; 578 tp = &it->tcb; 579 bzero(tp, sizeof(struct tcpcb)); 580 LIST_INIT(&tp->t_segq); 581 tp->t_maxseg = tp->t_maxopd = isipv6 ? tcp_v6mssdflt : tcp_mssdflt; 582 583 /* Set up our timeouts. */ 584 callout_init(tp->tt_rexmt = &it->inp_tp_rexmt); 585 callout_init(tp->tt_persist = &it->inp_tp_persist); 586 callout_init(tp->tt_keep = &it->inp_tp_keep); 587 callout_init(tp->tt_2msl = &it->inp_tp_2msl); 588 callout_init(tp->tt_delack = &it->inp_tp_delack); 589 590 if (tcp_do_rfc1323) 591 tp->t_flags = (TF_REQ_SCALE | TF_REQ_TSTMP); 592 if (tcp_do_rfc1644) 593 tp->t_flags |= TF_REQ_CC; 594 tp->t_inpcb = inp; /* XXX */ 595 /* 596 * Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no 597 * rtt estimate. Set rttvar so that srtt + 4 * rttvar gives 598 * reasonable initial retransmit time. 599 */ 600 tp->t_srtt = TCPTV_SRTTBASE; 601 tp->t_rttvar = 602 ((TCPTV_RTOBASE - TCPTV_SRTTBASE) << TCP_RTTVAR_SHIFT) / 4; 603 tp->t_rttmin = tcp_rexmit_min; 604 tp->t_rxtcur = TCPTV_RTOBASE; 605 tp->snd_cwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 606 tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 607 tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT; 608 tp->t_rcvtime = ticks; 609 tp->t_bw_rtttime = ticks; 610 /* 611 * IPv4 TTL initialization is necessary for an IPv6 socket as well, 612 * because the socket may be bound to an IPv6 wildcard address, 613 * which may match an IPv4-mapped IPv6 address. 614 */ 615 inp->inp_ip_ttl = ip_defttl; 616 inp->inp_ppcb = (caddr_t)tp; 617 return (tp); /* XXX */ 618 } 619 620 /* 621 * Drop a TCP connection, reporting the specified error. 622 * If connection is synchronized, then send a RST to peer. 623 */ 624 struct tcpcb * 625 tcp_drop(struct tcpcb *tp, int errno) 626 { 627 struct socket *so = tp->t_inpcb->inp_socket; 628 629 if (TCPS_HAVERCVDSYN(tp->t_state)) { 630 tp->t_state = TCPS_CLOSED; 631 (void) tcp_output(tp); 632 tcpstat.tcps_drops++; 633 } else 634 tcpstat.tcps_conndrops++; 635 if (errno == ETIMEDOUT && tp->t_softerror) 636 errno = tp->t_softerror; 637 so->so_error = errno; 638 return (tcp_close(tp)); 639 } 640 641 #ifdef SMP 642 struct netmsg_remwildcard { 643 struct lwkt_msg nm_lmsg; 644 struct inpcb *nm_inp; 645 struct inpcbinfo *nm_pcbinfo; 646 }; 647 648 static int 649 in_pcbremwildcardhash_handler(struct lwkt_msg *msg0) 650 { 651 struct netmsg_remwildcard *msg = (struct netmsg_remwildcard *)msg0; 652 653 in_pcbremwildcardhash_oncpu(msg->nm_inp, msg->nm_pcbinfo); 654 lwkt_replymsg(&msg->nm_lmsg, 0); 655 return (EASYNC); 656 } 657 #endif 658 659 /* 660 * Close a TCP control block: 661 * discard all space held by the tcp 662 * discard internet protocol block 663 * wake up any sleepers 664 */ 665 struct tcpcb * 666 tcp_close(struct tcpcb *tp) 667 { 668 struct tseg_qent *q; 669 struct inpcb *inp = tp->t_inpcb; 670 struct socket *so = inp->inp_socket; 671 struct rtentry *rt; 672 boolean_t dosavessthresh; 673 #ifdef SMP 674 int cpu; 675 #endif 676 #ifdef INET6 677 boolean_t isipv6 = ((inp->inp_vflag & INP_IPV6) != 0); 678 #else 679 const boolean_t isipv6 = FALSE; 680 #endif 681 682 /* 683 * Make sure that all of our timers are stopped before we 684 * delete the PCB. 685 */ 686 callout_stop(tp->tt_rexmt); 687 callout_stop(tp->tt_persist); 688 callout_stop(tp->tt_keep); 689 callout_stop(tp->tt_2msl); 690 callout_stop(tp->tt_delack); 691 692 /* 693 * If we got enough samples through the srtt filter, 694 * save the rtt and rttvar in the routing entry. 695 * 'Enough' is arbitrarily defined as the 16 samples. 696 * 16 samples is enough for the srtt filter to converge 697 * to within 5% of the correct value; fewer samples and 698 * we could save a very bogus rtt. 699 * 700 * Don't update the default route's characteristics and don't 701 * update anything that the user "locked". 702 */ 703 if (tp->t_rttupdated >= 16) { 704 u_long i = 0; 705 706 if (isipv6) { 707 struct sockaddr_in6 *sin6; 708 709 if ((rt = inp->in6p_route.ro_rt) == NULL) 710 goto no_valid_rt; 711 sin6 = (struct sockaddr_in6 *)rt_key(rt); 712 if (IN6_IS_ADDR_UNSPECIFIED(&sin6->sin6_addr)) 713 goto no_valid_rt; 714 } else 715 if ((rt = inp->inp_route.ro_rt) == NULL || 716 ((struct sockaddr_in *)rt_key(rt))-> 717 sin_addr.s_addr == INADDR_ANY) 718 goto no_valid_rt; 719 720 if (!(rt->rt_rmx.rmx_locks & RTV_RTT)) { 721 i = tp->t_srtt * (RTM_RTTUNIT / (hz * TCP_RTT_SCALE)); 722 if (rt->rt_rmx.rmx_rtt && i) 723 /* 724 * filter this update to half the old & half 725 * the new values, converting scale. 726 * See route.h and tcp_var.h for a 727 * description of the scaling constants. 728 */ 729 rt->rt_rmx.rmx_rtt = 730 (rt->rt_rmx.rmx_rtt + i) / 2; 731 else 732 rt->rt_rmx.rmx_rtt = i; 733 tcpstat.tcps_cachedrtt++; 734 } 735 if (!(rt->rt_rmx.rmx_locks & RTV_RTTVAR)) { 736 i = tp->t_rttvar * 737 (RTM_RTTUNIT / (hz * TCP_RTTVAR_SCALE)); 738 if (rt->rt_rmx.rmx_rttvar && i) 739 rt->rt_rmx.rmx_rttvar = 740 (rt->rt_rmx.rmx_rttvar + i) / 2; 741 else 742 rt->rt_rmx.rmx_rttvar = i; 743 tcpstat.tcps_cachedrttvar++; 744 } 745 /* 746 * The old comment here said: 747 * update the pipelimit (ssthresh) if it has been updated 748 * already or if a pipesize was specified & the threshhold 749 * got below half the pipesize. I.e., wait for bad news 750 * before we start updating, then update on both good 751 * and bad news. 752 * 753 * But we want to save the ssthresh even if no pipesize is 754 * specified explicitly in the route, because such 755 * connections still have an implicit pipesize specified 756 * by the global tcp_sendspace. In the absence of a reliable 757 * way to calculate the pipesize, it will have to do. 758 */ 759 i = tp->snd_ssthresh; 760 if (rt->rt_rmx.rmx_sendpipe != 0) 761 dosavessthresh = (i < rt->rt_rmx.rmx_sendpipe/2); 762 else 763 dosavessthresh = (i < so->so_snd.sb_hiwat/2); 764 if (dosavessthresh || 765 (!(rt->rt_rmx.rmx_locks & RTV_SSTHRESH) && (i != 0) && 766 (rt->rt_rmx.rmx_ssthresh != 0))) { 767 /* 768 * convert the limit from user data bytes to 769 * packets then to packet data bytes. 770 */ 771 i = (i + tp->t_maxseg / 2) / tp->t_maxseg; 772 if (i < 2) 773 i = 2; 774 i *= tp->t_maxseg + 775 (isipv6 ? 776 sizeof(struct ip6_hdr) + sizeof(struct tcphdr) : 777 sizeof(struct tcpiphdr)); 778 if (rt->rt_rmx.rmx_ssthresh) 779 rt->rt_rmx.rmx_ssthresh = 780 (rt->rt_rmx.rmx_ssthresh + i) / 2; 781 else 782 rt->rt_rmx.rmx_ssthresh = i; 783 tcpstat.tcps_cachedssthresh++; 784 } 785 } 786 787 no_valid_rt: 788 /* free the reassembly queue, if any */ 789 while((q = LIST_FIRST(&tp->t_segq)) != NULL) { 790 LIST_REMOVE(q, tqe_q); 791 m_freem(q->tqe_m); 792 FREE(q, M_TSEGQ); 793 tcp_reass_qsize--; 794 } 795 inp->inp_ppcb = NULL; 796 soisdisconnected(so); 797 798 #ifdef SMP 799 if (inp->inp_flags & INP_WILDCARD_MP) { 800 for (cpu = 0; cpu < ncpus2; cpu ++) { 801 struct netmsg_remwildcard *msg; 802 803 msg = malloc(sizeof(struct netmsg_remwildcard), 804 M_LWKTMSG, M_INTWAIT); 805 lwkt_initmsg(&msg->nm_lmsg, &netisr_afree_rport, 0, 806 lwkt_cmd_func(in_pcbremwildcardhash_handler), 807 lwkt_cmd_op_none); 808 msg->nm_inp = inp; 809 msg->nm_pcbinfo = &tcbinfo[cpu]; 810 lwkt_sendmsg(tcp_cport(cpu), &msg->nm_lmsg); 811 } 812 } 813 #endif 814 815 #ifdef INET6 816 if (INP_CHECK_SOCKAF(so, AF_INET6)) 817 in6_pcbdetach(inp); 818 else 819 #endif 820 in_pcbdetach(inp); 821 tcpstat.tcps_closed++; 822 return (NULL); 823 } 824 825 static __inline void 826 tcp_drain_oncpu(struct inpcbhead *head) 827 { 828 struct inpcb *inpb; 829 struct tcpcb *tcpb; 830 struct tseg_qent *te; 831 832 LIST_FOREACH(inpb, head, inp_list) { 833 if (inpb->inp_flags & INP_PLACEMARKER) 834 continue; 835 if ((tcpb = intotcpcb(inpb))) { 836 while ((te = LIST_FIRST(&tcpb->t_segq)) != NULL) { 837 LIST_REMOVE(te, tqe_q); 838 m_freem(te->tqe_m); 839 FREE(te, M_TSEGQ); 840 tcp_reass_qsize--; 841 } 842 } 843 } 844 } 845 846 #ifdef SMP 847 struct netmsg_tcp_drain { 848 struct lwkt_msg nm_lmsg; 849 struct inpcbhead *nm_head; 850 }; 851 852 static int 853 tcp_drain_handler(lwkt_msg_t lmsg) 854 { 855 struct netmsg_tcp_drain *nm = (void *)lmsg; 856 857 tcp_drain_oncpu(nm->nm_head); 858 lwkt_replymsg(lmsg, 0); 859 return(EASYNC); 860 } 861 #endif 862 863 void 864 tcp_drain() 865 { 866 #ifdef SMP 867 int cpu; 868 #endif 869 870 if (!do_tcpdrain) 871 return; 872 873 /* 874 * Walk the tcpbs, if existing, and flush the reassembly queue, 875 * if there is one... 876 * XXX: The "Net/3" implementation doesn't imply that the TCP 877 * reassembly queue should be flushed, but in a situation 878 * where we're really low on mbufs, this is potentially 879 * useful. 880 */ 881 #ifdef SMP 882 for (cpu = 0; cpu < ncpus2; cpu++) { 883 struct netmsg_tcp_drain *msg; 884 885 if (cpu == mycpu->gd_cpuid) { 886 tcp_drain_oncpu(&tcbinfo[cpu].pcblisthead); 887 } else { 888 msg = malloc(sizeof(struct netmsg_tcp_drain), 889 M_LWKTMSG, M_NOWAIT); 890 if (msg == NULL) 891 continue; 892 lwkt_initmsg(&msg->nm_lmsg, &netisr_afree_rport, 0, 893 lwkt_cmd_func(tcp_drain_handler), 894 lwkt_cmd_op_none); 895 msg->nm_head = &tcbinfo[cpu].pcblisthead; 896 lwkt_sendmsg(tcp_cport(cpu), &msg->nm_lmsg); 897 } 898 } 899 #else 900 tcp_drain_oncpu(&tcbinfo[0].pcblisthead); 901 #endif 902 } 903 904 /* 905 * Notify a tcp user of an asynchronous error; 906 * store error as soft error, but wake up user 907 * (for now, won't do anything until can select for soft error). 908 * 909 * Do not wake up user since there currently is no mechanism for 910 * reporting soft errors (yet - a kqueue filter may be added). 911 */ 912 static void 913 tcp_notify(struct inpcb *inp, int error) 914 { 915 struct tcpcb *tp = intotcpcb(inp); 916 917 /* 918 * Ignore some errors if we are hooked up. 919 * If connection hasn't completed, has retransmitted several times, 920 * and receives a second error, give up now. This is better 921 * than waiting a long time to establish a connection that 922 * can never complete. 923 */ 924 if (tp->t_state == TCPS_ESTABLISHED && 925 (error == EHOSTUNREACH || error == ENETUNREACH || 926 error == EHOSTDOWN)) { 927 return; 928 } else if (tp->t_state < TCPS_ESTABLISHED && tp->t_rxtshift > 3 && 929 tp->t_softerror) 930 tcp_drop(tp, error); 931 else 932 tp->t_softerror = error; 933 #if 0 934 wakeup((caddr_t) &so->so_timeo); 935 sorwakeup(so); 936 sowwakeup(so); 937 #endif 938 } 939 940 static int 941 tcp_pcblist(SYSCTL_HANDLER_ARGS) 942 { 943 int error, i, n; 944 struct inpcb *marker; 945 struct inpcb *inp; 946 inp_gen_t gencnt; 947 struct xinpgen xig; 948 globaldata_t gd; 949 int origcpu, ccpu; 950 951 error = 0; 952 n = 0; 953 954 /* 955 * The process of preparing the TCB list is too time-consuming and 956 * resource-intensive to repeat twice on every request. 957 */ 958 if (req->oldptr == NULL) { 959 for (ccpu = 0; ccpu < ncpus; ++ccpu) { 960 gd = globaldata_find(ccpu); 961 n += tcbinfo[gd->gd_cpuid].ipi_count; 962 } 963 req->oldidx = 2 * ncpus * (sizeof xig) + 964 (n + n/8) * sizeof(struct xtcpcb); 965 return (0); 966 } 967 968 if (req->newptr != NULL) 969 return (EPERM); 970 971 marker = malloc(sizeof(struct inpcb), M_TEMP, M_WAITOK|M_ZERO); 972 marker->inp_flags |= INP_PLACEMARKER; 973 974 /* 975 * OK, now we're committed to doing something. Run the inpcb list 976 * for each cpu in the system and construct the output. Use a 977 * list placemarker to deal with list changes occuring during 978 * copyout blockages (but otherwise depend on being on the correct 979 * cpu to avoid races). 980 */ 981 origcpu = mycpu->gd_cpuid; 982 for (ccpu = 1; ccpu <= ncpus && error == 0; ++ccpu) { 983 globaldata_t rgd; 984 caddr_t inp_ppcb; 985 struct xtcpcb xt; 986 int cpu_id; 987 988 cpu_id = (origcpu + ccpu) % ncpus; 989 if ((smp_active_mask & (1 << cpu_id)) == 0) 990 continue; 991 rgd = globaldata_find(cpu_id); 992 lwkt_setcpu_self(rgd); 993 994 /* indicate change of CPU */ 995 cpu_mb1(); 996 997 gencnt = tcbinfo[cpu_id].ipi_gencnt; 998 n = tcbinfo[cpu_id].ipi_count; 999 1000 xig.xig_len = sizeof xig; 1001 xig.xig_count = n; 1002 xig.xig_gen = gencnt; 1003 xig.xig_sogen = so_gencnt; 1004 xig.xig_cpu = cpu_id; 1005 error = SYSCTL_OUT(req, &xig, sizeof xig); 1006 if (error != 0) 1007 break; 1008 1009 LIST_INSERT_HEAD(&tcbinfo[cpu_id].pcblisthead, marker, inp_list); 1010 i = 0; 1011 while ((inp = LIST_NEXT(marker, inp_list)) != NULL && i < n) { 1012 /* 1013 * process a snapshot of pcbs, ignoring placemarkers 1014 * and using our own to allow SYSCTL_OUT to block. 1015 */ 1016 LIST_REMOVE(marker, inp_list); 1017 LIST_INSERT_AFTER(inp, marker, inp_list); 1018 1019 if (inp->inp_flags & INP_PLACEMARKER) 1020 continue; 1021 if (inp->inp_gencnt > gencnt) 1022 continue; 1023 if (prison_xinpcb(req->td, inp)) 1024 continue; 1025 1026 xt.xt_len = sizeof xt; 1027 bcopy(inp, &xt.xt_inp, sizeof *inp); 1028 inp_ppcb = inp->inp_ppcb; 1029 if (inp_ppcb != NULL) 1030 bcopy(inp_ppcb, &xt.xt_tp, sizeof xt.xt_tp); 1031 else 1032 bzero(&xt.xt_tp, sizeof xt.xt_tp); 1033 if (inp->inp_socket) 1034 sotoxsocket(inp->inp_socket, &xt.xt_socket); 1035 if ((error = SYSCTL_OUT(req, &xt, sizeof xt)) != 0) 1036 break; 1037 ++i; 1038 } 1039 LIST_REMOVE(marker, inp_list); 1040 if (error == 0 && i < n) { 1041 bzero(&xt, sizeof(xt)); 1042 xt.xt_len = sizeof(xt); 1043 while (i < n) { 1044 error = SYSCTL_OUT(req, &xt, sizeof (xt)); 1045 if (error) 1046 break; 1047 ++i; 1048 } 1049 } 1050 if (error == 0) { 1051 /* 1052 * Give the user an updated idea of our state. 1053 * If the generation differs from what we told 1054 * her before, she knows that something happened 1055 * while we were processing this request, and it 1056 * might be necessary to retry. 1057 */ 1058 xig.xig_gen = tcbinfo[cpu_id].ipi_gencnt; 1059 xig.xig_sogen = so_gencnt; 1060 xig.xig_count = tcbinfo[cpu_id].ipi_count; 1061 error = SYSCTL_OUT(req, &xig, sizeof xig); 1062 } 1063 } 1064 1065 /* 1066 * Make sure we are on the same cpu we were on originally, since 1067 * higher level callers expect this. Also don't pollute caches with 1068 * migrated userland data by (eventually) returning to userland 1069 * on a different cpu. 1070 */ 1071 lwkt_setcpu_self(globaldata_find(origcpu)); 1072 free(marker, M_TEMP); 1073 return (error); 1074 } 1075 1076 SYSCTL_PROC(_net_inet_tcp, TCPCTL_PCBLIST, pcblist, CTLFLAG_RD, 0, 0, 1077 tcp_pcblist, "S,xtcpcb", "List of active TCP connections"); 1078 1079 static int 1080 tcp_getcred(SYSCTL_HANDLER_ARGS) 1081 { 1082 struct sockaddr_in addrs[2]; 1083 struct inpcb *inp; 1084 int cpu; 1085 int error, s; 1086 1087 error = suser(req->td); 1088 if (error != 0) 1089 return (error); 1090 error = SYSCTL_IN(req, addrs, sizeof addrs); 1091 if (error != 0) 1092 return (error); 1093 s = splnet(); 1094 1095 cpu = tcp_addrcpu(addrs[1].sin_addr.s_addr, addrs[1].sin_port, 1096 addrs[0].sin_addr.s_addr, addrs[0].sin_port); 1097 inp = in_pcblookup_hash(&tcbinfo[cpu], addrs[1].sin_addr, 1098 addrs[1].sin_port, addrs[0].sin_addr, addrs[0].sin_port, 0, NULL); 1099 if (inp == NULL || inp->inp_socket == NULL) { 1100 error = ENOENT; 1101 goto out; 1102 } 1103 error = SYSCTL_OUT(req, inp->inp_socket->so_cred, sizeof(struct ucred)); 1104 out: 1105 splx(s); 1106 return (error); 1107 } 1108 1109 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, getcred, (CTLTYPE_OPAQUE | CTLFLAG_RW), 1110 0, 0, tcp_getcred, "S,ucred", "Get the ucred of a TCP connection"); 1111 1112 #ifdef INET6 1113 static int 1114 tcp6_getcred(SYSCTL_HANDLER_ARGS) 1115 { 1116 struct sockaddr_in6 addrs[2]; 1117 struct inpcb *inp; 1118 int error, s; 1119 boolean_t mapped = FALSE; 1120 1121 error = suser(req->td); 1122 if (error != 0) 1123 return (error); 1124 error = SYSCTL_IN(req, addrs, sizeof addrs); 1125 if (error != 0) 1126 return (error); 1127 if (IN6_IS_ADDR_V4MAPPED(&addrs[0].sin6_addr)) { 1128 if (IN6_IS_ADDR_V4MAPPED(&addrs[1].sin6_addr)) 1129 mapped = TRUE; 1130 else 1131 return (EINVAL); 1132 } 1133 s = splnet(); 1134 if (mapped) { 1135 inp = in_pcblookup_hash(&tcbinfo[0], 1136 *(struct in_addr *)&addrs[1].sin6_addr.s6_addr[12], 1137 addrs[1].sin6_port, 1138 *(struct in_addr *)&addrs[0].sin6_addr.s6_addr[12], 1139 addrs[0].sin6_port, 1140 0, NULL); 1141 } else { 1142 inp = in6_pcblookup_hash(&tcbinfo[0], 1143 &addrs[1].sin6_addr, addrs[1].sin6_port, 1144 &addrs[0].sin6_addr, addrs[0].sin6_port, 1145 0, NULL); 1146 } 1147 if (inp == NULL || inp->inp_socket == NULL) { 1148 error = ENOENT; 1149 goto out; 1150 } 1151 error = SYSCTL_OUT(req, inp->inp_socket->so_cred, sizeof(struct ucred)); 1152 out: 1153 splx(s); 1154 return (error); 1155 } 1156 1157 SYSCTL_PROC(_net_inet6_tcp6, OID_AUTO, getcred, (CTLTYPE_OPAQUE | CTLFLAG_RW), 1158 0, 0, 1159 tcp6_getcred, "S,ucred", "Get the ucred of a TCP6 connection"); 1160 #endif 1161 1162 void 1163 tcp_ctlinput(int cmd, struct sockaddr *sa, void *vip) 1164 { 1165 struct ip *ip = vip; 1166 struct tcphdr *th; 1167 struct in_addr faddr; 1168 struct inpcb *inp; 1169 struct tcpcb *tp; 1170 void (*notify)(struct inpcb *, int) = tcp_notify; 1171 tcp_seq icmp_seq; 1172 int cpu; 1173 int s; 1174 1175 faddr = ((struct sockaddr_in *)sa)->sin_addr; 1176 if (sa->sa_family != AF_INET || faddr.s_addr == INADDR_ANY) 1177 return; 1178 1179 if (cmd == PRC_QUENCH) 1180 notify = tcp_quench; 1181 else if (icmp_may_rst && 1182 (cmd == PRC_UNREACH_ADMIN_PROHIB || cmd == PRC_UNREACH_PORT || 1183 cmd == PRC_TIMXCEED_INTRANS) && 1184 ip != NULL) 1185 notify = tcp_drop_syn_sent; 1186 else if (cmd == PRC_MSGSIZE) 1187 notify = tcp_mtudisc; 1188 else if (PRC_IS_REDIRECT(cmd)) { 1189 ip = NULL; 1190 notify = in_rtchange; 1191 } else if (cmd == PRC_HOSTDEAD) 1192 ip = NULL; 1193 else if ((unsigned)cmd > PRC_NCMDS || inetctlerrmap[cmd] == 0) 1194 return; 1195 if (ip != NULL) { 1196 s = splnet(); 1197 th = (struct tcphdr *)((caddr_t)ip + 1198 (IP_VHL_HL(ip->ip_vhl) << 2)); 1199 cpu = tcp_addrcpu(faddr.s_addr, th->th_dport, 1200 ip->ip_src.s_addr, th->th_sport); 1201 inp = in_pcblookup_hash(&tcbinfo[cpu], faddr, th->th_dport, 1202 ip->ip_src, th->th_sport, 0, NULL); 1203 if ((inp != NULL) && (inp->inp_socket != NULL)) { 1204 icmp_seq = htonl(th->th_seq); 1205 tp = intotcpcb(inp); 1206 if (SEQ_GEQ(icmp_seq, tp->snd_una) && 1207 SEQ_LT(icmp_seq, tp->snd_max)) 1208 (*notify)(inp, inetctlerrmap[cmd]); 1209 } else { 1210 struct in_conninfo inc; 1211 1212 inc.inc_fport = th->th_dport; 1213 inc.inc_lport = th->th_sport; 1214 inc.inc_faddr = faddr; 1215 inc.inc_laddr = ip->ip_src; 1216 #ifdef INET6 1217 inc.inc_isipv6 = 0; 1218 #endif 1219 syncache_unreach(&inc, th); 1220 } 1221 splx(s); 1222 } else { 1223 for (cpu = 0; cpu < ncpus2; cpu++) { 1224 in_pcbnotifyall(&tcbinfo[cpu].pcblisthead, faddr, 1225 inetctlerrmap[cmd], notify); 1226 } 1227 } 1228 } 1229 1230 #ifdef INET6 1231 void 1232 tcp6_ctlinput(int cmd, struct sockaddr *sa, void *d) 1233 { 1234 struct tcphdr th; 1235 void (*notify) (struct inpcb *, int) = tcp_notify; 1236 struct ip6_hdr *ip6; 1237 struct mbuf *m; 1238 struct ip6ctlparam *ip6cp = NULL; 1239 const struct sockaddr_in6 *sa6_src = NULL; 1240 int off; 1241 struct tcp_portonly { 1242 u_int16_t th_sport; 1243 u_int16_t th_dport; 1244 } *thp; 1245 1246 if (sa->sa_family != AF_INET6 || 1247 sa->sa_len != sizeof(struct sockaddr_in6)) 1248 return; 1249 1250 if (cmd == PRC_QUENCH) 1251 notify = tcp_quench; 1252 else if (cmd == PRC_MSGSIZE) 1253 notify = tcp_mtudisc; 1254 else if (!PRC_IS_REDIRECT(cmd) && 1255 ((unsigned)cmd > PRC_NCMDS || inet6ctlerrmap[cmd] == 0)) 1256 return; 1257 1258 /* if the parameter is from icmp6, decode it. */ 1259 if (d != NULL) { 1260 ip6cp = (struct ip6ctlparam *)d; 1261 m = ip6cp->ip6c_m; 1262 ip6 = ip6cp->ip6c_ip6; 1263 off = ip6cp->ip6c_off; 1264 sa6_src = ip6cp->ip6c_src; 1265 } else { 1266 m = NULL; 1267 ip6 = NULL; 1268 off = 0; /* fool gcc */ 1269 sa6_src = &sa6_any; 1270 } 1271 1272 if (ip6 != NULL) { 1273 struct in_conninfo inc; 1274 /* 1275 * XXX: We assume that when IPV6 is non NULL, 1276 * M and OFF are valid. 1277 */ 1278 1279 /* check if we can safely examine src and dst ports */ 1280 if (m->m_pkthdr.len < off + sizeof *thp) 1281 return; 1282 1283 bzero(&th, sizeof th); 1284 m_copydata(m, off, sizeof *thp, (caddr_t)&th); 1285 1286 in6_pcbnotify(&tcbinfo[0].pcblisthead, sa, th.th_dport, 1287 (struct sockaddr *)ip6cp->ip6c_src, 1288 th.th_sport, cmd, notify); 1289 1290 inc.inc_fport = th.th_dport; 1291 inc.inc_lport = th.th_sport; 1292 inc.inc6_faddr = ((struct sockaddr_in6 *)sa)->sin6_addr; 1293 inc.inc6_laddr = ip6cp->ip6c_src->sin6_addr; 1294 inc.inc_isipv6 = 1; 1295 syncache_unreach(&inc, &th); 1296 } else 1297 in6_pcbnotify(&tcbinfo[0].pcblisthead, sa, 0, 1298 (const struct sockaddr *)sa6_src, 0, cmd, notify); 1299 } 1300 #endif 1301 1302 /* 1303 * Following is where TCP initial sequence number generation occurs. 1304 * 1305 * There are two places where we must use initial sequence numbers: 1306 * 1. In SYN-ACK packets. 1307 * 2. In SYN packets. 1308 * 1309 * All ISNs for SYN-ACK packets are generated by the syncache. See 1310 * tcp_syncache.c for details. 1311 * 1312 * The ISNs in SYN packets must be monotonic; TIME_WAIT recycling 1313 * depends on this property. In addition, these ISNs should be 1314 * unguessable so as to prevent connection hijacking. To satisfy 1315 * the requirements of this situation, the algorithm outlined in 1316 * RFC 1948 is used to generate sequence numbers. 1317 * 1318 * Implementation details: 1319 * 1320 * Time is based off the system timer, and is corrected so that it 1321 * increases by one megabyte per second. This allows for proper 1322 * recycling on high speed LANs while still leaving over an hour 1323 * before rollover. 1324 * 1325 * net.inet.tcp.isn_reseed_interval controls the number of seconds 1326 * between seeding of isn_secret. This is normally set to zero, 1327 * as reseeding should not be necessary. 1328 * 1329 */ 1330 1331 #define ISN_BYTES_PER_SECOND 1048576 1332 1333 u_char isn_secret[32]; 1334 int isn_last_reseed; 1335 MD5_CTX isn_ctx; 1336 1337 tcp_seq 1338 tcp_new_isn(struct tcpcb *tp) 1339 { 1340 u_int32_t md5_buffer[4]; 1341 tcp_seq new_isn; 1342 1343 /* Seed if this is the first use, reseed if requested. */ 1344 if ((isn_last_reseed == 0) || ((tcp_isn_reseed_interval > 0) && 1345 (((u_int)isn_last_reseed + (u_int)tcp_isn_reseed_interval*hz) 1346 < (u_int)ticks))) { 1347 read_random_unlimited(&isn_secret, sizeof isn_secret); 1348 isn_last_reseed = ticks; 1349 } 1350 1351 /* Compute the md5 hash and return the ISN. */ 1352 MD5Init(&isn_ctx); 1353 MD5Update(&isn_ctx, (u_char *)&tp->t_inpcb->inp_fport, sizeof(u_short)); 1354 MD5Update(&isn_ctx, (u_char *)&tp->t_inpcb->inp_lport, sizeof(u_short)); 1355 #ifdef INET6 1356 if (tp->t_inpcb->inp_vflag & INP_IPV6) { 1357 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_faddr, 1358 sizeof(struct in6_addr)); 1359 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_laddr, 1360 sizeof(struct in6_addr)); 1361 } else 1362 #endif 1363 { 1364 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_faddr, 1365 sizeof(struct in_addr)); 1366 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_laddr, 1367 sizeof(struct in_addr)); 1368 } 1369 MD5Update(&isn_ctx, (u_char *) &isn_secret, sizeof(isn_secret)); 1370 MD5Final((u_char *) &md5_buffer, &isn_ctx); 1371 new_isn = (tcp_seq) md5_buffer[0]; 1372 new_isn += ticks * (ISN_BYTES_PER_SECOND / hz); 1373 return (new_isn); 1374 } 1375 1376 /* 1377 * When a source quench is received, close congestion window 1378 * to one segment. We will gradually open it again as we proceed. 1379 */ 1380 void 1381 tcp_quench(struct inpcb *inp, int errno) 1382 { 1383 struct tcpcb *tp = intotcpcb(inp); 1384 1385 if (tp != NULL) 1386 tp->snd_cwnd = tp->t_maxseg; 1387 } 1388 1389 /* 1390 * When a specific ICMP unreachable message is received and the 1391 * connection state is SYN-SENT, drop the connection. This behavior 1392 * is controlled by the icmp_may_rst sysctl. 1393 */ 1394 void 1395 tcp_drop_syn_sent(struct inpcb *inp, int errno) 1396 { 1397 struct tcpcb *tp = intotcpcb(inp); 1398 1399 if ((tp != NULL) && (tp->t_state == TCPS_SYN_SENT)) 1400 tcp_drop(tp, errno); 1401 } 1402 1403 /* 1404 * When `need fragmentation' ICMP is received, update our idea of the MSS 1405 * based on the new value in the route. Also nudge TCP to send something, 1406 * since we know the packet we just sent was dropped. 1407 * This duplicates some code in the tcp_mss() function in tcp_input.c. 1408 */ 1409 void 1410 tcp_mtudisc(struct inpcb *inp, int errno) 1411 { 1412 struct tcpcb *tp = intotcpcb(inp); 1413 struct rtentry *rt; 1414 struct rmxp_tao *taop; 1415 struct socket *so = inp->inp_socket; 1416 int offered; 1417 int mss; 1418 #ifdef INET6 1419 boolean_t isipv6 = ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0); 1420 #else 1421 const boolean_t isipv6 = FALSE; 1422 #endif 1423 1424 if (tp != NULL) { 1425 if (isipv6) 1426 rt = tcp_rtlookup6(&inp->inp_inc); 1427 else 1428 rt = tcp_rtlookup(&inp->inp_inc); 1429 if (rt == NULL || rt->rt_rmx.rmx_mtu == 0) { 1430 tp->t_maxopd = tp->t_maxseg = 1431 isipv6 ? tcp_v6mssdflt : tcp_mssdflt; 1432 return; 1433 } 1434 taop = rmx_taop(rt->rt_rmx); 1435 offered = taop->tao_mssopt; 1436 mss = rt->rt_rmx.rmx_mtu - 1437 (isipv6 ? 1438 sizeof(struct ip6_hdr) + sizeof(struct tcphdr) : 1439 sizeof(struct tcpiphdr)); 1440 1441 if (offered != 0) 1442 mss = min(mss, offered); 1443 /* 1444 * XXX - The above conditional probably violates the TCP 1445 * spec. The problem is that, since we don't know the 1446 * other end's MSS, we are supposed to use a conservative 1447 * default. But, if we do that, then MTU discovery will 1448 * never actually take place, because the conservative 1449 * default is much less than the MTUs typically seen 1450 * on the Internet today. For the moment, we'll sweep 1451 * this under the carpet. 1452 * 1453 * The conservative default might not actually be a problem 1454 * if the only case this occurs is when sending an initial 1455 * SYN with options and data to a host we've never talked 1456 * to before. Then, they will reply with an MSS value which 1457 * will get recorded and the new parameters should get 1458 * recomputed. For Further Study. 1459 */ 1460 if (tp->t_maxopd <= mss) 1461 return; 1462 tp->t_maxopd = mss; 1463 1464 if ((tp->t_flags & (TF_REQ_TSTMP | TF_NOOPT)) == TF_REQ_TSTMP && 1465 (tp->t_flags & TF_RCVD_TSTMP) == TF_RCVD_TSTMP) 1466 mss -= TCPOLEN_TSTAMP_APPA; 1467 if ((tp->t_flags & (TF_REQ_CC | TF_NOOPT)) == TF_REQ_CC && 1468 (tp->t_flags & TF_RCVD_CC) == TF_RCVD_CC) 1469 mss -= TCPOLEN_CC_APPA; 1470 #if (MCLBYTES & (MCLBYTES - 1)) == 0 1471 if (mss > MCLBYTES) 1472 mss &= ~(MCLBYTES - 1); 1473 #else 1474 if (mss > MCLBYTES) 1475 mss = mss / MCLBYTES * MCLBYTES; 1476 #endif 1477 if (so->so_snd.sb_hiwat < mss) 1478 mss = so->so_snd.sb_hiwat; 1479 1480 tp->t_maxseg = mss; 1481 1482 tcpstat.tcps_mturesent++; 1483 tp->t_rtttime = 0; 1484 tp->snd_nxt = tp->snd_una; 1485 tcp_output(tp); 1486 } 1487 } 1488 1489 /* 1490 * Look-up the routing entry to the peer of this inpcb. If no route 1491 * is found and it cannot be allocated the return NULL. This routine 1492 * is called by TCP routines that access the rmx structure and by tcp_mss 1493 * to get the interface MTU. 1494 */ 1495 struct rtentry * 1496 tcp_rtlookup(struct in_conninfo *inc) 1497 { 1498 struct route *ro; 1499 struct rtentry *rt; 1500 1501 ro = &inc->inc_route; 1502 rt = ro->ro_rt; 1503 if (rt == NULL || !(rt->rt_flags & RTF_UP)) { 1504 /* No route yet, so try to acquire one */ 1505 if (inc->inc_faddr.s_addr != INADDR_ANY) { 1506 ro->ro_dst.sa_family = AF_INET; 1507 ro->ro_dst.sa_len = sizeof(struct sockaddr_in); 1508 ((struct sockaddr_in *) &ro->ro_dst)->sin_addr = 1509 inc->inc_faddr; 1510 rtalloc(ro); 1511 rt = ro->ro_rt; 1512 } 1513 } 1514 return (rt); 1515 } 1516 1517 #ifdef INET6 1518 struct rtentry * 1519 tcp_rtlookup6(struct in_conninfo *inc) 1520 { 1521 struct route_in6 *ro6; 1522 struct rtentry *rt; 1523 1524 ro6 = &inc->inc6_route; 1525 rt = ro6->ro_rt; 1526 if (rt == NULL || !(rt->rt_flags & RTF_UP)) { 1527 /* No route yet, so try to acquire one */ 1528 if (!IN6_IS_ADDR_UNSPECIFIED(&inc->inc6_faddr)) { 1529 ro6->ro_dst.sin6_family = AF_INET6; 1530 ro6->ro_dst.sin6_len = sizeof(struct sockaddr_in6); 1531 ro6->ro_dst.sin6_addr = inc->inc6_faddr; 1532 rtalloc((struct route *)ro6); 1533 rt = ro6->ro_rt; 1534 } 1535 } 1536 return (rt); 1537 } 1538 #endif 1539 1540 #ifdef IPSEC 1541 /* compute ESP/AH header size for TCP, including outer IP header. */ 1542 size_t 1543 ipsec_hdrsiz_tcp(struct tcpcb *tp) 1544 { 1545 struct inpcb *inp; 1546 struct mbuf *m; 1547 size_t hdrsiz; 1548 struct ip *ip; 1549 struct tcphdr *th; 1550 1551 if ((tp == NULL) || ((inp = tp->t_inpcb) == NULL)) 1552 return (0); 1553 MGETHDR(m, MB_DONTWAIT, MT_DATA); 1554 if (!m) 1555 return (0); 1556 1557 #ifdef INET6 1558 if (inp->inp_vflag & INP_IPV6) { 1559 struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *); 1560 1561 th = (struct tcphdr *)(ip6 + 1); 1562 m->m_pkthdr.len = m->m_len = 1563 sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 1564 tcp_fillheaders(tp, ip6, th); 1565 hdrsiz = ipsec6_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp); 1566 } else 1567 #endif 1568 { 1569 ip = mtod(m, struct ip *); 1570 th = (struct tcphdr *)(ip + 1); 1571 m->m_pkthdr.len = m->m_len = sizeof(struct tcpiphdr); 1572 tcp_fillheaders(tp, ip, th); 1573 hdrsiz = ipsec4_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp); 1574 } 1575 1576 m_free(m); 1577 return (hdrsiz); 1578 } 1579 #endif 1580 1581 /* 1582 * Return a pointer to the cached information about the remote host. 1583 * The cached information is stored in the protocol specific part of 1584 * the route metrics. 1585 */ 1586 struct rmxp_tao * 1587 tcp_gettaocache(struct in_conninfo *inc) 1588 { 1589 struct rtentry *rt; 1590 1591 #ifdef INET6 1592 if (inc->inc_isipv6) 1593 rt = tcp_rtlookup6(inc); 1594 else 1595 #endif 1596 rt = tcp_rtlookup(inc); 1597 1598 /* Make sure this is a host route and is up. */ 1599 if (rt == NULL || 1600 (rt->rt_flags & (RTF_UP | RTF_HOST)) != (RTF_UP | RTF_HOST)) 1601 return (NULL); 1602 1603 return (rmx_taop(rt->rt_rmx)); 1604 } 1605 1606 /* 1607 * Clear all the TAO cache entries, called from tcp_init. 1608 * 1609 * XXX 1610 * This routine is just an empty one, because we assume that the routing 1611 * routing tables are initialized at the same time when TCP, so there is 1612 * nothing in the cache left over. 1613 */ 1614 static void 1615 tcp_cleartaocache() 1616 { 1617 } 1618 1619 /* 1620 * TCP BANDWIDTH DELAY PRODUCT WINDOW LIMITING 1621 * 1622 * This code attempts to calculate the bandwidth-delay product as a 1623 * means of determining the optimal window size to maximize bandwidth, 1624 * minimize RTT, and avoid the over-allocation of buffers on interfaces and 1625 * routers. This code also does a fairly good job keeping RTTs in check 1626 * across slow links like modems. We implement an algorithm which is very 1627 * similar (but not meant to be) TCP/Vegas. The code operates on the 1628 * transmitter side of a TCP connection and so only effects the transmit 1629 * side of the connection. 1630 * 1631 * BACKGROUND: TCP makes no provision for the management of buffer space 1632 * at the end points or at the intermediate routers and switches. A TCP 1633 * stream, whether using NewReno or not, will eventually buffer as 1634 * many packets as it is able and the only reason this typically works is 1635 * due to the fairly small default buffers made available for a connection 1636 * (typicaly 16K or 32K). As machines use larger windows and/or window 1637 * scaling it is now fairly easy for even a single TCP connection to blow-out 1638 * all available buffer space not only on the local interface, but on 1639 * intermediate routers and switches as well. NewReno makes a misguided 1640 * attempt to 'solve' this problem by waiting for an actual failure to occur, 1641 * then backing off, then steadily increasing the window again until another 1642 * failure occurs, ad-infinitum. This results in terrible oscillation that 1643 * is only made worse as network loads increase and the idea of intentionally 1644 * blowing out network buffers is, frankly, a terrible way to manage network 1645 * resources. 1646 * 1647 * It is far better to limit the transmit window prior to the failure 1648 * condition being achieved. There are two general ways to do this: First 1649 * you can 'scan' through different transmit window sizes and locate the 1650 * point where the RTT stops increasing, indicating that you have filled the 1651 * pipe, then scan backwards until you note that RTT stops decreasing, then 1652 * repeat ad-infinitum. This method works in principle but has severe 1653 * implementation issues due to RTT variances, timer granularity, and 1654 * instability in the algorithm which can lead to many false positives and 1655 * create oscillations as well as interact badly with other TCP streams 1656 * implementing the same algorithm. 1657 * 1658 * The second method is to limit the window to the bandwidth delay product 1659 * of the link. This is the method we implement. RTT variances and our 1660 * own manipulation of the congestion window, bwnd, can potentially 1661 * destabilize the algorithm. For this reason we have to stabilize the 1662 * elements used to calculate the window. We do this by using the minimum 1663 * observed RTT, the long term average of the observed bandwidth, and 1664 * by adding two segments worth of slop. It isn't perfect but it is able 1665 * to react to changing conditions and gives us a very stable basis on 1666 * which to extend the algorithm. 1667 */ 1668 void 1669 tcp_xmit_bandwidth_limit(struct tcpcb *tp, tcp_seq ack_seq) 1670 { 1671 u_long bw; 1672 u_long bwnd; 1673 int save_ticks; 1674 1675 /* 1676 * If inflight_enable is disabled in the middle of a tcp connection, 1677 * make sure snd_bwnd is effectively disabled. 1678 */ 1679 if (!tcp_inflight_enable) { 1680 tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 1681 tp->snd_bandwidth = 0; 1682 return; 1683 } 1684 1685 /* 1686 * Figure out the bandwidth. Due to the tick granularity this 1687 * is a very rough number and it MUST be averaged over a fairly 1688 * long period of time. XXX we need to take into account a link 1689 * that is not using all available bandwidth, but for now our 1690 * slop will ramp us up if this case occurs and the bandwidth later 1691 * increases. 1692 * 1693 * Note: if ticks rollover 'bw' may wind up negative. We must 1694 * effectively reset t_bw_rtttime for this case. 1695 */ 1696 save_ticks = ticks; 1697 if ((u_int)(save_ticks - tp->t_bw_rtttime) < 1) 1698 return; 1699 1700 bw = (int64_t)(ack_seq - tp->t_bw_rtseq) * hz / 1701 (save_ticks - tp->t_bw_rtttime); 1702 tp->t_bw_rtttime = save_ticks; 1703 tp->t_bw_rtseq = ack_seq; 1704 if (tp->t_bw_rtttime == 0 || (int)bw < 0) 1705 return; 1706 bw = ((int64_t)tp->snd_bandwidth * 15 + bw) >> 4; 1707 1708 tp->snd_bandwidth = bw; 1709 1710 /* 1711 * Calculate the semi-static bandwidth delay product, plus two maximal 1712 * segments. The additional slop puts us squarely in the sweet 1713 * spot and also handles the bandwidth run-up case. Without the 1714 * slop we could be locking ourselves into a lower bandwidth. 1715 * 1716 * Situations Handled: 1717 * (1) Prevents over-queueing of packets on LANs, especially on 1718 * high speed LANs, allowing larger TCP buffers to be 1719 * specified, and also does a good job preventing 1720 * over-queueing of packets over choke points like modems 1721 * (at least for the transmit side). 1722 * 1723 * (2) Is able to handle changing network loads (bandwidth 1724 * drops so bwnd drops, bandwidth increases so bwnd 1725 * increases). 1726 * 1727 * (3) Theoretically should stabilize in the face of multiple 1728 * connections implementing the same algorithm (this may need 1729 * a little work). 1730 * 1731 * (4) Stability value (defaults to 20 = 2 maximal packets) can 1732 * be adjusted with a sysctl but typically only needs to be on 1733 * very slow connections. A value no smaller then 5 should 1734 * be used, but only reduce this default if you have no other 1735 * choice. 1736 */ 1737 1738 #define USERTT ((tp->t_srtt + tp->t_rttbest) / 2) 1739 bwnd = (int64_t)bw * USERTT / (hz << TCP_RTT_SHIFT) + 1740 tcp_inflight_stab * (int)tp->t_maxseg / 10; 1741 #undef USERTT 1742 1743 if (tcp_inflight_debug > 0) { 1744 static int ltime; 1745 if ((u_int)(ticks - ltime) >= hz / tcp_inflight_debug) { 1746 ltime = ticks; 1747 printf("%p bw %ld rttbest %d srtt %d bwnd %ld\n", 1748 tp, bw, tp->t_rttbest, tp->t_srtt, bwnd); 1749 } 1750 } 1751 if ((long)bwnd < tcp_inflight_min) 1752 bwnd = tcp_inflight_min; 1753 if (bwnd > tcp_inflight_max) 1754 bwnd = tcp_inflight_max; 1755 if ((long)bwnd < tp->t_maxseg * 2) 1756 bwnd = tp->t_maxseg * 2; 1757 tp->snd_bwnd = bwnd; 1758 } 1759