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 1.8 2003/08/23 11:18:00 rob 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/mbuf.h> 50 #ifdef INET6 51 #include <sys/domain.h> 52 #endif 53 #include <sys/proc.h> 54 #include <sys/socket.h> 55 #include <sys/socketvar.h> 56 #include <sys/protosw.h> 57 #include <sys/random.h> 58 59 #include <vm/vm_zone.h> 60 61 #include <net/route.h> 62 #include <net/if.h> 63 64 #define _IP_VHL 65 #include <netinet/in.h> 66 #include <netinet/in_systm.h> 67 #include <netinet/ip.h> 68 #ifdef INET6 69 #include <netinet/ip6.h> 70 #endif 71 #include <netinet/in_pcb.h> 72 #ifdef INET6 73 #include <netinet6/in6_pcb.h> 74 #endif 75 #include <netinet/in_var.h> 76 #include <netinet/ip_var.h> 77 #ifdef INET6 78 #include <netinet6/ip6_var.h> 79 #endif 80 #include <netinet/tcp.h> 81 #include <netinet/tcp_fsm.h> 82 #include <netinet/tcp_seq.h> 83 #include <netinet/tcp_timer.h> 84 #include <netinet/tcp_var.h> 85 #ifdef INET6 86 #include <netinet6/tcp6_var.h> 87 #endif 88 #include <netinet/tcpip.h> 89 #ifdef TCPDEBUG 90 #include <netinet/tcp_debug.h> 91 #endif 92 #include <netinet6/ip6protosw.h> 93 94 #ifdef IPSEC 95 #include <netinet6/ipsec.h> 96 #ifdef INET6 97 #include <netinet6/ipsec6.h> 98 #endif 99 #endif /*IPSEC*/ 100 101 #ifdef FAST_IPSEC 102 #include <netipsec/ipsec.h> 103 #ifdef INET6 104 #include <netipsec/ipsec6.h> 105 #endif 106 #define IPSEC 107 #endif /*FAST_IPSEC*/ 108 109 #include <machine/in_cksum.h> 110 #include <sys/md5.h> 111 112 int tcp_mssdflt = TCP_MSS; 113 SYSCTL_INT(_net_inet_tcp, TCPCTL_MSSDFLT, mssdflt, CTLFLAG_RW, 114 &tcp_mssdflt , 0, "Default TCP Maximum Segment Size"); 115 116 #ifdef INET6 117 int tcp_v6mssdflt = TCP6_MSS; 118 SYSCTL_INT(_net_inet_tcp, TCPCTL_V6MSSDFLT, v6mssdflt, 119 CTLFLAG_RW, &tcp_v6mssdflt , 0, 120 "Default TCP Maximum Segment Size for IPv6"); 121 #endif 122 123 #if 0 124 static int tcp_rttdflt = TCPTV_SRTTDFLT / PR_SLOWHZ; 125 SYSCTL_INT(_net_inet_tcp, TCPCTL_RTTDFLT, rttdflt, CTLFLAG_RW, 126 &tcp_rttdflt , 0, "Default maximum TCP Round Trip Time"); 127 #endif 128 129 int tcp_do_rfc1323 = 1; 130 SYSCTL_INT(_net_inet_tcp, TCPCTL_DO_RFC1323, rfc1323, CTLFLAG_RW, 131 &tcp_do_rfc1323 , 0, "Enable rfc1323 (high performance TCP) extensions"); 132 133 int tcp_do_rfc1644 = 0; 134 SYSCTL_INT(_net_inet_tcp, TCPCTL_DO_RFC1644, rfc1644, CTLFLAG_RW, 135 &tcp_do_rfc1644 , 0, "Enable rfc1644 (TTCP) extensions"); 136 137 static int tcp_tcbhashsize = 0; 138 SYSCTL_INT(_net_inet_tcp, OID_AUTO, tcbhashsize, CTLFLAG_RD, 139 &tcp_tcbhashsize, 0, "Size of TCP control-block hashtable"); 140 141 static int do_tcpdrain = 1; 142 SYSCTL_INT(_net_inet_tcp, OID_AUTO, do_tcpdrain, CTLFLAG_RW, &do_tcpdrain, 0, 143 "Enable tcp_drain routine for extra help when low on mbufs"); 144 145 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pcbcount, CTLFLAG_RD, 146 &tcbinfo.ipi_count, 0, "Number of active PCBs"); 147 148 static int icmp_may_rst = 1; 149 SYSCTL_INT(_net_inet_tcp, OID_AUTO, icmp_may_rst, CTLFLAG_RW, &icmp_may_rst, 0, 150 "Certain ICMP unreachable messages may abort connections in SYN_SENT"); 151 152 static int tcp_isn_reseed_interval = 0; 153 SYSCTL_INT(_net_inet_tcp, OID_AUTO, isn_reseed_interval, CTLFLAG_RW, 154 &tcp_isn_reseed_interval, 0, "Seconds between reseeding of ISN secret"); 155 156 /* 157 * TCP bandwidth limiting sysctls. Note that the default lower bound of 158 * 1024 exists only for debugging. A good production default would be 159 * something like 6100. 160 */ 161 static int tcp_inflight_enable = 0; 162 SYSCTL_INT(_net_inet_tcp, OID_AUTO, inflight_enable, CTLFLAG_RW, 163 &tcp_inflight_enable, 0, "Enable automatic TCP inflight data limiting"); 164 165 static int tcp_inflight_debug = 0; 166 SYSCTL_INT(_net_inet_tcp, OID_AUTO, inflight_debug, CTLFLAG_RW, 167 &tcp_inflight_debug, 0, "Debug TCP inflight calculations"); 168 169 static int tcp_inflight_min = 6144; 170 SYSCTL_INT(_net_inet_tcp, OID_AUTO, inflight_min, CTLFLAG_RW, 171 &tcp_inflight_min, 0, "Lower-bound for TCP inflight window"); 172 173 static int tcp_inflight_max = TCP_MAXWIN << TCP_MAX_WINSHIFT; 174 SYSCTL_INT(_net_inet_tcp, OID_AUTO, inflight_max, CTLFLAG_RW, 175 &tcp_inflight_max, 0, "Upper-bound for TCP inflight window"); 176 177 static int tcp_inflight_stab = 20; 178 SYSCTL_INT(_net_inet_tcp, OID_AUTO, inflight_stab, CTLFLAG_RW, 179 &tcp_inflight_stab, 0, "Slop in maximal packets / 10 (20 = 2 packets)"); 180 181 static void tcp_cleartaocache (void); 182 static void tcp_notify (struct inpcb *, int); 183 184 /* 185 * Target size of TCP PCB hash tables. Must be a power of two. 186 * 187 * Note that this can be overridden by the kernel environment 188 * variable net.inet.tcp.tcbhashsize 189 */ 190 #ifndef TCBHASHSIZE 191 #define TCBHASHSIZE 512 192 #endif 193 194 /* 195 * This is the actual shape of what we allocate using the zone 196 * allocator. Doing it this way allows us to protect both structures 197 * using the same generation count, and also eliminates the overhead 198 * of allocating tcpcbs separately. By hiding the structure here, 199 * we avoid changing most of the rest of the code (although it needs 200 * to be changed, eventually, for greater efficiency). 201 */ 202 #define ALIGNMENT 32 203 #define ALIGNM1 (ALIGNMENT - 1) 204 struct inp_tp { 205 union { 206 struct inpcb inp; 207 char align[(sizeof(struct inpcb) + ALIGNM1) & ~ALIGNM1]; 208 } inp_tp_u; 209 struct tcpcb tcb; 210 struct callout inp_tp_rexmt, inp_tp_persist, inp_tp_keep, inp_tp_2msl; 211 struct callout inp_tp_delack; 212 }; 213 #undef ALIGNMENT 214 #undef ALIGNM1 215 216 /* 217 * Tcp initialization 218 */ 219 void 220 tcp_init() 221 { 222 int hashsize = TCBHASHSIZE; 223 224 tcp_ccgen = 1; 225 tcp_cleartaocache(); 226 227 tcp_delacktime = TCPTV_DELACK; 228 tcp_keepinit = TCPTV_KEEP_INIT; 229 tcp_keepidle = TCPTV_KEEP_IDLE; 230 tcp_keepintvl = TCPTV_KEEPINTVL; 231 tcp_maxpersistidle = TCPTV_KEEP_IDLE; 232 tcp_msl = TCPTV_MSL; 233 tcp_rexmit_min = TCPTV_MIN; 234 tcp_rexmit_slop = TCPTV_CPU_VAR; 235 236 LIST_INIT(&tcb); 237 tcbinfo.listhead = &tcb; 238 TUNABLE_INT_FETCH("net.inet.tcp.tcbhashsize", &hashsize); 239 if (!powerof2(hashsize)) { 240 printf("WARNING: TCB hash size not a power of 2\n"); 241 hashsize = 512; /* safe default */ 242 } 243 tcp_tcbhashsize = hashsize; 244 tcbinfo.hashbase = hashinit(hashsize, M_PCB, &tcbinfo.hashmask); 245 tcbinfo.porthashbase = hashinit(hashsize, M_PCB, 246 &tcbinfo.porthashmask); 247 tcbinfo.ipi_zone = zinit("tcpcb", sizeof(struct inp_tp), maxsockets, 248 ZONE_INTERRUPT, 0); 249 #ifdef INET6 250 #define TCP_MINPROTOHDR (sizeof(struct ip6_hdr) + sizeof(struct tcphdr)) 251 #else /* INET6 */ 252 #define TCP_MINPROTOHDR (sizeof(struct tcpiphdr)) 253 #endif /* INET6 */ 254 if (max_protohdr < TCP_MINPROTOHDR) 255 max_protohdr = TCP_MINPROTOHDR; 256 if (max_linkhdr + TCP_MINPROTOHDR > MHLEN) 257 panic("tcp_init"); 258 #undef TCP_MINPROTOHDR 259 260 syncache_init(); 261 } 262 263 /* 264 * Fill in the IP and TCP headers for an outgoing packet, given the tcpcb. 265 * tcp_template used to store this data in mbufs, but we now recopy it out 266 * of the tcpcb each time to conserve mbufs. 267 */ 268 void 269 tcp_fillheaders(tp, ip_ptr, tcp_ptr) 270 struct tcpcb *tp; 271 void *ip_ptr; 272 void *tcp_ptr; 273 { 274 struct inpcb *inp = tp->t_inpcb; 275 struct tcphdr *tcp_hdr = (struct tcphdr *)tcp_ptr; 276 277 #ifdef INET6 278 if ((inp->inp_vflag & INP_IPV6) != 0) { 279 struct ip6_hdr *ip6; 280 281 ip6 = (struct ip6_hdr *)ip_ptr; 282 ip6->ip6_flow = (ip6->ip6_flow & ~IPV6_FLOWINFO_MASK) | 283 (inp->in6p_flowinfo & IPV6_FLOWINFO_MASK); 284 ip6->ip6_vfc = (ip6->ip6_vfc & ~IPV6_VERSION_MASK) | 285 (IPV6_VERSION & IPV6_VERSION_MASK); 286 ip6->ip6_nxt = IPPROTO_TCP; 287 ip6->ip6_plen = sizeof(struct tcphdr); 288 ip6->ip6_src = inp->in6p_laddr; 289 ip6->ip6_dst = inp->in6p_faddr; 290 tcp_hdr->th_sum = 0; 291 } else 292 #endif 293 { 294 struct ip *ip = (struct ip *) ip_ptr; 295 296 ip->ip_vhl = IP_VHL_BORING; 297 ip->ip_tos = 0; 298 ip->ip_len = 0; 299 ip->ip_id = 0; 300 ip->ip_off = 0; 301 ip->ip_ttl = 0; 302 ip->ip_sum = 0; 303 ip->ip_p = IPPROTO_TCP; 304 ip->ip_src = inp->inp_laddr; 305 ip->ip_dst = inp->inp_faddr; 306 tcp_hdr->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr, 307 htons(sizeof(struct tcphdr) + IPPROTO_TCP)); 308 } 309 310 tcp_hdr->th_sport = inp->inp_lport; 311 tcp_hdr->th_dport = inp->inp_fport; 312 tcp_hdr->th_seq = 0; 313 tcp_hdr->th_ack = 0; 314 tcp_hdr->th_x2 = 0; 315 tcp_hdr->th_off = 5; 316 tcp_hdr->th_flags = 0; 317 tcp_hdr->th_win = 0; 318 tcp_hdr->th_urp = 0; 319 } 320 321 /* 322 * Create template to be used to send tcp packets on a connection. 323 * Allocates an mbuf and fills in a skeletal tcp/ip header. The only 324 * use for this function is in keepalives, which use tcp_respond. 325 */ 326 struct tcptemp * 327 tcp_maketemplate(tp) 328 struct tcpcb *tp; 329 { 330 struct mbuf *m; 331 struct tcptemp *n; 332 333 m = m_get(M_DONTWAIT, MT_HEADER); 334 if (m == NULL) 335 return (0); 336 m->m_len = sizeof(struct tcptemp); 337 n = mtod(m, struct tcptemp *); 338 339 tcp_fillheaders(tp, (void *)&n->tt_ipgen, (void *)&n->tt_t); 340 return (n); 341 } 342 343 /* 344 * Send a single message to the TCP at address specified by 345 * the given TCP/IP header. If m == 0, then we make a copy 346 * of the tcpiphdr at ti and send directly to the addressed host. 347 * This is used to force keep alive messages out using the TCP 348 * template for a connection. If flags are given then we send 349 * a message back to the TCP which originated the * segment ti, 350 * and discard the mbuf containing it and any other attached mbufs. 351 * 352 * In any case the ack and sequence number of the transmitted 353 * segment are as specified by the parameters. 354 * 355 * NOTE: If m != NULL, then ti must point to *inside* the mbuf. 356 */ 357 void 358 tcp_respond(tp, ipgen, th, m, ack, seq, flags) 359 struct tcpcb *tp; 360 void *ipgen; 361 struct tcphdr *th; 362 struct mbuf *m; 363 tcp_seq ack, seq; 364 int flags; 365 { 366 int tlen; 367 int win = 0; 368 struct route *ro = 0; 369 struct route sro; 370 struct ip *ip; 371 struct tcphdr *nth; 372 #ifdef INET6 373 struct route_in6 *ro6 = 0; 374 struct route_in6 sro6; 375 struct ip6_hdr *ip6; 376 int isipv6; 377 #endif /* INET6 */ 378 int ipflags = 0; 379 380 #ifdef INET6 381 isipv6 = IP_VHL_V(((struct ip *)ipgen)->ip_vhl) == 6; 382 ip6 = ipgen; 383 #endif /* INET6 */ 384 ip = ipgen; 385 386 if (tp) { 387 if (!(flags & TH_RST)) { 388 win = sbspace(&tp->t_inpcb->inp_socket->so_rcv); 389 if (win > (long)TCP_MAXWIN << tp->rcv_scale) 390 win = (long)TCP_MAXWIN << tp->rcv_scale; 391 } 392 #ifdef INET6 393 if (isipv6) 394 ro6 = &tp->t_inpcb->in6p_route; 395 else 396 #endif /* INET6 */ 397 ro = &tp->t_inpcb->inp_route; 398 } else { 399 #ifdef INET6 400 if (isipv6) { 401 ro6 = &sro6; 402 bzero(ro6, sizeof *ro6); 403 } else 404 #endif /* INET6 */ 405 { 406 ro = &sro; 407 bzero(ro, sizeof *ro); 408 } 409 } 410 if (m == 0) { 411 m = m_gethdr(M_DONTWAIT, MT_HEADER); 412 if (m == NULL) 413 return; 414 tlen = 0; 415 m->m_data += max_linkhdr; 416 #ifdef INET6 417 if (isipv6) { 418 bcopy((caddr_t)ip6, mtod(m, caddr_t), 419 sizeof(struct ip6_hdr)); 420 ip6 = mtod(m, struct ip6_hdr *); 421 nth = (struct tcphdr *)(ip6 + 1); 422 } else 423 #endif /* INET6 */ 424 { 425 bcopy((caddr_t)ip, mtod(m, caddr_t), sizeof(struct ip)); 426 ip = mtod(m, struct ip *); 427 nth = (struct tcphdr *)(ip + 1); 428 } 429 bcopy((caddr_t)th, (caddr_t)nth, sizeof(struct tcphdr)); 430 flags = TH_ACK; 431 } else { 432 m_freem(m->m_next); 433 m->m_next = 0; 434 m->m_data = (caddr_t)ipgen; 435 /* m_len is set later */ 436 tlen = 0; 437 #define xchg(a,b,type) { type t; t=a; a=b; b=t; } 438 #ifdef INET6 439 if (isipv6) { 440 xchg(ip6->ip6_dst, ip6->ip6_src, struct in6_addr); 441 nth = (struct tcphdr *)(ip6 + 1); 442 } else 443 #endif /* INET6 */ 444 { 445 xchg(ip->ip_dst.s_addr, ip->ip_src.s_addr, n_long); 446 nth = (struct tcphdr *)(ip + 1); 447 } 448 if (th != nth) { 449 /* 450 * this is usually a case when an extension header 451 * exists between the IPv6 header and the 452 * TCP header. 453 */ 454 nth->th_sport = th->th_sport; 455 nth->th_dport = th->th_dport; 456 } 457 xchg(nth->th_dport, nth->th_sport, n_short); 458 #undef xchg 459 } 460 #ifdef INET6 461 if (isipv6) { 462 ip6->ip6_flow = 0; 463 ip6->ip6_vfc = IPV6_VERSION; 464 ip6->ip6_nxt = IPPROTO_TCP; 465 ip6->ip6_plen = htons((u_short)(sizeof (struct tcphdr) + 466 tlen)); 467 tlen += sizeof (struct ip6_hdr) + sizeof (struct tcphdr); 468 } else 469 #endif 470 { 471 tlen += sizeof (struct tcpiphdr); 472 ip->ip_len = tlen; 473 ip->ip_ttl = ip_defttl; 474 } 475 m->m_len = tlen; 476 m->m_pkthdr.len = tlen; 477 m->m_pkthdr.rcvif = (struct ifnet *) 0; 478 nth->th_seq = htonl(seq); 479 nth->th_ack = htonl(ack); 480 nth->th_x2 = 0; 481 nth->th_off = sizeof (struct tcphdr) >> 2; 482 nth->th_flags = flags; 483 if (tp) 484 nth->th_win = htons((u_short) (win >> tp->rcv_scale)); 485 else 486 nth->th_win = htons((u_short)win); 487 nth->th_urp = 0; 488 #ifdef INET6 489 if (isipv6) { 490 nth->th_sum = 0; 491 nth->th_sum = in6_cksum(m, IPPROTO_TCP, 492 sizeof(struct ip6_hdr), 493 tlen - sizeof(struct ip6_hdr)); 494 ip6->ip6_hlim = in6_selecthlim(tp ? tp->t_inpcb : NULL, 495 ro6 && ro6->ro_rt ? 496 ro6->ro_rt->rt_ifp : 497 NULL); 498 } else 499 #endif /* INET6 */ 500 { 501 nth->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr, 502 htons((u_short)(tlen - sizeof(struct ip) + ip->ip_p))); 503 m->m_pkthdr.csum_flags = CSUM_TCP; 504 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 505 } 506 #ifdef TCPDEBUG 507 if (tp == NULL || (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) 508 tcp_trace(TA_OUTPUT, 0, tp, mtod(m, void *), th, 0); 509 #endif 510 #ifdef INET6 511 if (isipv6) { 512 (void)ip6_output(m, NULL, ro6, ipflags, NULL, NULL, 513 tp ? tp->t_inpcb : NULL); 514 if (ro6 == &sro6 && ro6->ro_rt) { 515 RTFREE(ro6->ro_rt); 516 ro6->ro_rt = NULL; 517 } 518 } else 519 #endif /* INET6 */ 520 { 521 (void) ip_output(m, NULL, ro, ipflags, NULL, tp ? tp->t_inpcb : NULL); 522 if (ro == &sro && ro->ro_rt) { 523 RTFREE(ro->ro_rt); 524 ro->ro_rt = NULL; 525 } 526 } 527 } 528 529 /* 530 * Create a new TCP control block, making an 531 * empty reassembly queue and hooking it to the argument 532 * protocol control block. The `inp' parameter must have 533 * come from the zone allocator set up in tcp_init(). 534 */ 535 struct tcpcb * 536 tcp_newtcpcb(inp) 537 struct inpcb *inp; 538 { 539 struct inp_tp *it; 540 struct tcpcb *tp; 541 #ifdef INET6 542 int isipv6 = (inp->inp_vflag & INP_IPV6) != 0; 543 #endif /* INET6 */ 544 545 it = (struct inp_tp *)inp; 546 tp = &it->tcb; 547 bzero((char *) tp, sizeof(struct tcpcb)); 548 LIST_INIT(&tp->t_segq); 549 tp->t_maxseg = tp->t_maxopd = 550 #ifdef INET6 551 isipv6 ? tcp_v6mssdflt : 552 #endif /* INET6 */ 553 tcp_mssdflt; 554 555 /* Set up our timeouts. */ 556 callout_init(tp->tt_rexmt = &it->inp_tp_rexmt); 557 callout_init(tp->tt_persist = &it->inp_tp_persist); 558 callout_init(tp->tt_keep = &it->inp_tp_keep); 559 callout_init(tp->tt_2msl = &it->inp_tp_2msl); 560 callout_init(tp->tt_delack = &it->inp_tp_delack); 561 562 if (tcp_do_rfc1323) 563 tp->t_flags = (TF_REQ_SCALE|TF_REQ_TSTMP); 564 if (tcp_do_rfc1644) 565 tp->t_flags |= TF_REQ_CC; 566 tp->t_inpcb = inp; /* XXX */ 567 /* 568 * Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no 569 * rtt estimate. Set rttvar so that srtt + 4 * rttvar gives 570 * reasonable initial retransmit time. 571 */ 572 tp->t_srtt = TCPTV_SRTTBASE; 573 tp->t_rttvar = ((TCPTV_RTOBASE - TCPTV_SRTTBASE) << TCP_RTTVAR_SHIFT) / 4; 574 tp->t_rttmin = tcp_rexmit_min; 575 tp->t_rxtcur = TCPTV_RTOBASE; 576 tp->snd_cwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 577 tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 578 tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT; 579 tp->t_rcvtime = ticks; 580 tp->t_bw_rtttime = ticks; 581 /* 582 * IPv4 TTL initialization is necessary for an IPv6 socket as well, 583 * because the socket may be bound to an IPv6 wildcard address, 584 * which may match an IPv4-mapped IPv6 address. 585 */ 586 inp->inp_ip_ttl = ip_defttl; 587 inp->inp_ppcb = (caddr_t)tp; 588 return (tp); /* XXX */ 589 } 590 591 /* 592 * Drop a TCP connection, reporting 593 * the specified error. If connection is synchronized, 594 * then send a RST to peer. 595 */ 596 struct tcpcb * 597 tcp_drop(tp, errno) 598 struct tcpcb *tp; 599 int errno; 600 { 601 struct socket *so = tp->t_inpcb->inp_socket; 602 603 if (TCPS_HAVERCVDSYN(tp->t_state)) { 604 tp->t_state = TCPS_CLOSED; 605 (void) tcp_output(tp); 606 tcpstat.tcps_drops++; 607 } else 608 tcpstat.tcps_conndrops++; 609 if (errno == ETIMEDOUT && tp->t_softerror) 610 errno = tp->t_softerror; 611 so->so_error = errno; 612 return (tcp_close(tp)); 613 } 614 615 /* 616 * Close a TCP control block: 617 * discard all space held by the tcp 618 * discard internet protocol block 619 * wake up any sleepers 620 */ 621 struct tcpcb * 622 tcp_close(tp) 623 struct tcpcb *tp; 624 { 625 struct tseg_qent *q; 626 struct inpcb *inp = tp->t_inpcb; 627 struct socket *so = inp->inp_socket; 628 #ifdef INET6 629 int isipv6 = (inp->inp_vflag & INP_IPV6) != 0; 630 #endif /* INET6 */ 631 struct rtentry *rt; 632 int dosavessthresh; 633 634 /* 635 * Make sure that all of our timers are stopped before we 636 * delete the PCB. 637 */ 638 callout_stop(tp->tt_rexmt); 639 callout_stop(tp->tt_persist); 640 callout_stop(tp->tt_keep); 641 callout_stop(tp->tt_2msl); 642 callout_stop(tp->tt_delack); 643 644 /* 645 * If we got enough samples through the srtt filter, 646 * save the rtt and rttvar in the routing entry. 647 * 'Enough' is arbitrarily defined as the 16 samples. 648 * 16 samples is enough for the srtt filter to converge 649 * to within 5% of the correct value; fewer samples and 650 * we could save a very bogus rtt. 651 * 652 * Don't update the default route's characteristics and don't 653 * update anything that the user "locked". 654 */ 655 if (tp->t_rttupdated >= 16) { 656 u_long i = 0; 657 #ifdef INET6 658 if (isipv6) { 659 struct sockaddr_in6 *sin6; 660 661 if ((rt = inp->in6p_route.ro_rt) == NULL) 662 goto no_valid_rt; 663 sin6 = (struct sockaddr_in6 *)rt_key(rt); 664 if (IN6_IS_ADDR_UNSPECIFIED(&sin6->sin6_addr)) 665 goto no_valid_rt; 666 } 667 else 668 #endif /* INET6 */ 669 if ((rt = inp->inp_route.ro_rt) == NULL || 670 ((struct sockaddr_in *)rt_key(rt))->sin_addr.s_addr 671 == INADDR_ANY) 672 goto no_valid_rt; 673 674 if ((rt->rt_rmx.rmx_locks & RTV_RTT) == 0) { 675 i = tp->t_srtt * 676 (RTM_RTTUNIT / (hz * TCP_RTT_SCALE)); 677 if (rt->rt_rmx.rmx_rtt && i) 678 /* 679 * filter this update to half the old & half 680 * the new values, converting scale. 681 * See route.h and tcp_var.h for a 682 * description of the scaling constants. 683 */ 684 rt->rt_rmx.rmx_rtt = 685 (rt->rt_rmx.rmx_rtt + i) / 2; 686 else 687 rt->rt_rmx.rmx_rtt = i; 688 tcpstat.tcps_cachedrtt++; 689 } 690 if ((rt->rt_rmx.rmx_locks & RTV_RTTVAR) == 0) { 691 i = tp->t_rttvar * 692 (RTM_RTTUNIT / (hz * TCP_RTTVAR_SCALE)); 693 if (rt->rt_rmx.rmx_rttvar && i) 694 rt->rt_rmx.rmx_rttvar = 695 (rt->rt_rmx.rmx_rttvar + i) / 2; 696 else 697 rt->rt_rmx.rmx_rttvar = i; 698 tcpstat.tcps_cachedrttvar++; 699 } 700 /* 701 * The old comment here said: 702 * update the pipelimit (ssthresh) if it has been updated 703 * already or if a pipesize was specified & the threshhold 704 * got below half the pipesize. I.e., wait for bad news 705 * before we start updating, then update on both good 706 * and bad news. 707 * 708 * But we want to save the ssthresh even if no pipesize is 709 * specified explicitly in the route, because such 710 * connections still have an implicit pipesize specified 711 * by the global tcp_sendspace. In the absence of a reliable 712 * way to calculate the pipesize, it will have to do. 713 */ 714 i = tp->snd_ssthresh; 715 if (rt->rt_rmx.rmx_sendpipe != 0) 716 dosavessthresh = (i < rt->rt_rmx.rmx_sendpipe / 2); 717 else 718 dosavessthresh = (i < so->so_snd.sb_hiwat / 2); 719 if (((rt->rt_rmx.rmx_locks & RTV_SSTHRESH) == 0 && 720 i != 0 && rt->rt_rmx.rmx_ssthresh != 0) 721 || dosavessthresh) { 722 /* 723 * convert the limit from user data bytes to 724 * packets then to packet data bytes. 725 */ 726 i = (i + tp->t_maxseg / 2) / tp->t_maxseg; 727 if (i < 2) 728 i = 2; 729 i *= (u_long)(tp->t_maxseg + 730 #ifdef INET6 731 (isipv6 ? sizeof (struct ip6_hdr) + 732 sizeof (struct tcphdr) : 733 #endif 734 sizeof (struct tcpiphdr) 735 #ifdef INET6 736 ) 737 #endif 738 ); 739 if (rt->rt_rmx.rmx_ssthresh) 740 rt->rt_rmx.rmx_ssthresh = 741 (rt->rt_rmx.rmx_ssthresh + i) / 2; 742 else 743 rt->rt_rmx.rmx_ssthresh = i; 744 tcpstat.tcps_cachedssthresh++; 745 } 746 } 747 no_valid_rt: 748 /* free the reassembly queue, if any */ 749 while((q = LIST_FIRST(&tp->t_segq)) != NULL) { 750 LIST_REMOVE(q, tqe_q); 751 m_freem(q->tqe_m); 752 FREE(q, M_TSEGQ); 753 } 754 inp->inp_ppcb = NULL; 755 soisdisconnected(so); 756 #ifdef INET6 757 if (INP_CHECK_SOCKAF(so, AF_INET6)) 758 in6_pcbdetach(inp); 759 else 760 #endif /* INET6 */ 761 in_pcbdetach(inp); 762 tcpstat.tcps_closed++; 763 return ((struct tcpcb *)0); 764 } 765 766 void 767 tcp_drain() 768 { 769 if (do_tcpdrain) 770 { 771 struct inpcb *inpb; 772 struct tcpcb *tcpb; 773 struct tseg_qent *te; 774 775 /* 776 * Walk the tcpbs, if existing, and flush the reassembly queue, 777 * if there is one... 778 * XXX: The "Net/3" implementation doesn't imply that the TCP 779 * reassembly queue should be flushed, but in a situation 780 * where we're really low on mbufs, this is potentially 781 * usefull. 782 */ 783 LIST_FOREACH(inpb, tcbinfo.listhead, inp_list) { 784 if ((tcpb = intotcpcb(inpb))) { 785 while ((te = LIST_FIRST(&tcpb->t_segq)) 786 != NULL) { 787 LIST_REMOVE(te, tqe_q); 788 m_freem(te->tqe_m); 789 FREE(te, M_TSEGQ); 790 } 791 } 792 } 793 794 } 795 } 796 797 /* 798 * Notify a tcp user of an asynchronous error; 799 * store error as soft error, but wake up user 800 * (for now, won't do anything until can select for soft error). 801 * 802 * Do not wake up user since there currently is no mechanism for 803 * reporting soft errors (yet - a kqueue filter may be added). 804 */ 805 static void 806 tcp_notify(inp, error) 807 struct inpcb *inp; 808 int error; 809 { 810 struct tcpcb *tp = (struct tcpcb *)inp->inp_ppcb; 811 812 /* 813 * Ignore some errors if we are hooked up. 814 * If connection hasn't completed, has retransmitted several times, 815 * and receives a second error, give up now. This is better 816 * than waiting a long time to establish a connection that 817 * can never complete. 818 */ 819 if (tp->t_state == TCPS_ESTABLISHED && 820 (error == EHOSTUNREACH || error == ENETUNREACH || 821 error == EHOSTDOWN)) { 822 return; 823 } else if (tp->t_state < TCPS_ESTABLISHED && tp->t_rxtshift > 3 && 824 tp->t_softerror) 825 tcp_drop(tp, error); 826 else 827 tp->t_softerror = error; 828 #if 0 829 wakeup((caddr_t) &so->so_timeo); 830 sorwakeup(so); 831 sowwakeup(so); 832 #endif 833 } 834 835 static int 836 tcp_pcblist(SYSCTL_HANDLER_ARGS) 837 { 838 int error, i, n, s; 839 struct inpcb *inp, **inp_list; 840 inp_gen_t gencnt; 841 struct xinpgen xig; 842 843 /* 844 * The process of preparing the TCB list is too time-consuming and 845 * resource-intensive to repeat twice on every request. 846 */ 847 if (req->oldptr == 0) { 848 n = tcbinfo.ipi_count; 849 req->oldidx = 2 * (sizeof xig) 850 + (n + n/8) * sizeof(struct xtcpcb); 851 return 0; 852 } 853 854 if (req->newptr != 0) 855 return EPERM; 856 857 /* 858 * OK, now we're committed to doing something. 859 */ 860 s = splnet(); 861 gencnt = tcbinfo.ipi_gencnt; 862 n = tcbinfo.ipi_count; 863 splx(s); 864 865 xig.xig_len = sizeof xig; 866 xig.xig_count = n; 867 xig.xig_gen = gencnt; 868 xig.xig_sogen = so_gencnt; 869 error = SYSCTL_OUT(req, &xig, sizeof xig); 870 if (error) 871 return error; 872 873 inp_list = malloc(n * sizeof *inp_list, M_TEMP, M_WAITOK); 874 if (inp_list == 0) 875 return ENOMEM; 876 877 s = splnet(); 878 for (inp = LIST_FIRST(tcbinfo.listhead), i = 0; inp && i < n; 879 inp = LIST_NEXT(inp, inp_list)) { 880 if (inp->inp_gencnt <= gencnt && !prison_xinpcb(req->td, inp)) 881 inp_list[i++] = inp; 882 } 883 splx(s); 884 n = i; 885 886 error = 0; 887 for (i = 0; i < n; i++) { 888 inp = inp_list[i]; 889 if (inp->inp_gencnt <= gencnt) { 890 struct xtcpcb xt; 891 caddr_t inp_ppcb; 892 xt.xt_len = sizeof xt; 893 /* XXX should avoid extra copy */ 894 bcopy(inp, &xt.xt_inp, sizeof *inp); 895 inp_ppcb = inp->inp_ppcb; 896 if (inp_ppcb != NULL) 897 bcopy(inp_ppcb, &xt.xt_tp, sizeof xt.xt_tp); 898 else 899 bzero((char *) &xt.xt_tp, sizeof xt.xt_tp); 900 if (inp->inp_socket) 901 sotoxsocket(inp->inp_socket, &xt.xt_socket); 902 error = SYSCTL_OUT(req, &xt, sizeof xt); 903 } 904 } 905 if (!error) { 906 /* 907 * Give the user an updated idea of our state. 908 * If the generation differs from what we told 909 * her before, she knows that something happened 910 * while we were processing this request, and it 911 * might be necessary to retry. 912 */ 913 s = splnet(); 914 xig.xig_gen = tcbinfo.ipi_gencnt; 915 xig.xig_sogen = so_gencnt; 916 xig.xig_count = tcbinfo.ipi_count; 917 splx(s); 918 error = SYSCTL_OUT(req, &xig, sizeof xig); 919 } 920 free(inp_list, M_TEMP); 921 return error; 922 } 923 924 SYSCTL_PROC(_net_inet_tcp, TCPCTL_PCBLIST, pcblist, CTLFLAG_RD, 0, 0, 925 tcp_pcblist, "S,xtcpcb", "List of active TCP connections"); 926 927 static int 928 tcp_getcred(SYSCTL_HANDLER_ARGS) 929 { 930 struct sockaddr_in addrs[2]; 931 struct inpcb *inp; 932 int error, s; 933 934 error = suser(req->td); 935 if (error) 936 return (error); 937 error = SYSCTL_IN(req, addrs, sizeof(addrs)); 938 if (error) 939 return (error); 940 s = splnet(); 941 inp = in_pcblookup_hash(&tcbinfo, addrs[1].sin_addr, addrs[1].sin_port, 942 addrs[0].sin_addr, addrs[0].sin_port, 0, NULL); 943 if (inp == NULL || inp->inp_socket == NULL) { 944 error = ENOENT; 945 goto out; 946 } 947 error = SYSCTL_OUT(req, inp->inp_socket->so_cred, sizeof(struct ucred)); 948 out: 949 splx(s); 950 return (error); 951 } 952 953 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, getcred, CTLTYPE_OPAQUE|CTLFLAG_RW, 954 0, 0, tcp_getcred, "S,ucred", "Get the ucred of a TCP connection"); 955 956 #ifdef INET6 957 static int 958 tcp6_getcred(SYSCTL_HANDLER_ARGS) 959 { 960 struct sockaddr_in6 addrs[2]; 961 struct inpcb *inp; 962 int error, s, mapped = 0; 963 964 error = suser(req->td); 965 if (error) 966 return (error); 967 error = SYSCTL_IN(req, addrs, sizeof(addrs)); 968 if (error) 969 return (error); 970 if (IN6_IS_ADDR_V4MAPPED(&addrs[0].sin6_addr)) { 971 if (IN6_IS_ADDR_V4MAPPED(&addrs[1].sin6_addr)) 972 mapped = 1; 973 else 974 return (EINVAL); 975 } 976 s = splnet(); 977 if (mapped == 1) 978 inp = in_pcblookup_hash(&tcbinfo, 979 *(struct in_addr *)&addrs[1].sin6_addr.s6_addr[12], 980 addrs[1].sin6_port, 981 *(struct in_addr *)&addrs[0].sin6_addr.s6_addr[12], 982 addrs[0].sin6_port, 983 0, NULL); 984 else 985 inp = in6_pcblookup_hash(&tcbinfo, &addrs[1].sin6_addr, 986 addrs[1].sin6_port, 987 &addrs[0].sin6_addr, addrs[0].sin6_port, 988 0, NULL); 989 if (inp == NULL || inp->inp_socket == NULL) { 990 error = ENOENT; 991 goto out; 992 } 993 error = SYSCTL_OUT(req, inp->inp_socket->so_cred, 994 sizeof(struct ucred)); 995 out: 996 splx(s); 997 return (error); 998 } 999 1000 SYSCTL_PROC(_net_inet6_tcp6, OID_AUTO, getcred, CTLTYPE_OPAQUE|CTLFLAG_RW, 1001 0, 0, 1002 tcp6_getcred, "S,ucred", "Get the ucred of a TCP6 connection"); 1003 #endif 1004 1005 1006 void 1007 tcp_ctlinput(cmd, sa, vip) 1008 int cmd; 1009 struct sockaddr *sa; 1010 void *vip; 1011 { 1012 struct ip *ip = vip; 1013 struct tcphdr *th; 1014 struct in_addr faddr; 1015 struct inpcb *inp; 1016 struct tcpcb *tp; 1017 void (*notify) (struct inpcb *, int) = tcp_notify; 1018 tcp_seq icmp_seq; 1019 int s; 1020 1021 faddr = ((struct sockaddr_in *)sa)->sin_addr; 1022 if (sa->sa_family != AF_INET || faddr.s_addr == INADDR_ANY) 1023 return; 1024 1025 if (cmd == PRC_QUENCH) 1026 notify = tcp_quench; 1027 else if (icmp_may_rst && (cmd == PRC_UNREACH_ADMIN_PROHIB || 1028 cmd == PRC_UNREACH_PORT || cmd == PRC_TIMXCEED_INTRANS) && ip) 1029 notify = tcp_drop_syn_sent; 1030 else if (cmd == PRC_MSGSIZE) 1031 notify = tcp_mtudisc; 1032 else if (PRC_IS_REDIRECT(cmd)) { 1033 ip = 0; 1034 notify = in_rtchange; 1035 } else if (cmd == PRC_HOSTDEAD) 1036 ip = 0; 1037 else if ((unsigned)cmd > PRC_NCMDS || inetctlerrmap[cmd] == 0) 1038 return; 1039 if (ip) { 1040 s = splnet(); 1041 th = (struct tcphdr *)((caddr_t)ip 1042 + (IP_VHL_HL(ip->ip_vhl) << 2)); 1043 inp = in_pcblookup_hash(&tcbinfo, faddr, th->th_dport, 1044 ip->ip_src, th->th_sport, 0, NULL); 1045 if (inp != NULL && inp->inp_socket != NULL) { 1046 icmp_seq = htonl(th->th_seq); 1047 tp = intotcpcb(inp); 1048 if (SEQ_GEQ(icmp_seq, tp->snd_una) && 1049 SEQ_LT(icmp_seq, tp->snd_max)) 1050 (*notify)(inp, inetctlerrmap[cmd]); 1051 } else { 1052 struct in_conninfo inc; 1053 1054 inc.inc_fport = th->th_dport; 1055 inc.inc_lport = th->th_sport; 1056 inc.inc_faddr = faddr; 1057 inc.inc_laddr = ip->ip_src; 1058 #ifdef INET6 1059 inc.inc_isipv6 = 0; 1060 #endif 1061 syncache_unreach(&inc, th); 1062 } 1063 splx(s); 1064 } else 1065 in_pcbnotifyall(&tcb, faddr, inetctlerrmap[cmd], notify); 1066 } 1067 1068 #ifdef INET6 1069 void 1070 tcp6_ctlinput(cmd, sa, d) 1071 int cmd; 1072 struct sockaddr *sa; 1073 void *d; 1074 { 1075 struct tcphdr th; 1076 void (*notify) (struct inpcb *, int) = tcp_notify; 1077 struct ip6_hdr *ip6; 1078 struct mbuf *m; 1079 struct ip6ctlparam *ip6cp = NULL; 1080 const struct sockaddr_in6 *sa6_src = NULL; 1081 int off; 1082 struct tcp_portonly { 1083 u_int16_t th_sport; 1084 u_int16_t th_dport; 1085 } *thp; 1086 1087 if (sa->sa_family != AF_INET6 || 1088 sa->sa_len != sizeof(struct sockaddr_in6)) 1089 return; 1090 1091 if (cmd == PRC_QUENCH) 1092 notify = tcp_quench; 1093 else if (cmd == PRC_MSGSIZE) 1094 notify = tcp_mtudisc; 1095 else if (!PRC_IS_REDIRECT(cmd) && 1096 ((unsigned)cmd > PRC_NCMDS || inet6ctlerrmap[cmd] == 0)) 1097 return; 1098 1099 /* if the parameter is from icmp6, decode it. */ 1100 if (d != NULL) { 1101 ip6cp = (struct ip6ctlparam *)d; 1102 m = ip6cp->ip6c_m; 1103 ip6 = ip6cp->ip6c_ip6; 1104 off = ip6cp->ip6c_off; 1105 sa6_src = ip6cp->ip6c_src; 1106 } else { 1107 m = NULL; 1108 ip6 = NULL; 1109 off = 0; /* fool gcc */ 1110 sa6_src = &sa6_any; 1111 } 1112 1113 if (ip6) { 1114 struct in_conninfo inc; 1115 /* 1116 * XXX: We assume that when IPV6 is non NULL, 1117 * M and OFF are valid. 1118 */ 1119 1120 /* check if we can safely examine src and dst ports */ 1121 if (m->m_pkthdr.len < off + sizeof(*thp)) 1122 return; 1123 1124 bzero(&th, sizeof(th)); 1125 m_copydata(m, off, sizeof(*thp), (caddr_t)&th); 1126 1127 in6_pcbnotify(&tcb, sa, th.th_dport, 1128 (struct sockaddr *)ip6cp->ip6c_src, 1129 th.th_sport, cmd, notify); 1130 1131 inc.inc_fport = th.th_dport; 1132 inc.inc_lport = th.th_sport; 1133 inc.inc6_faddr = ((struct sockaddr_in6 *)sa)->sin6_addr; 1134 inc.inc6_laddr = ip6cp->ip6c_src->sin6_addr; 1135 inc.inc_isipv6 = 1; 1136 syncache_unreach(&inc, &th); 1137 } else 1138 in6_pcbnotify(&tcb, sa, 0, (const struct sockaddr *)sa6_src, 1139 0, cmd, notify); 1140 } 1141 #endif /* INET6 */ 1142 1143 1144 /* 1145 * Following is where TCP initial sequence number generation occurs. 1146 * 1147 * There are two places where we must use initial sequence numbers: 1148 * 1. In SYN-ACK packets. 1149 * 2. In SYN packets. 1150 * 1151 * All ISNs for SYN-ACK packets are generated by the syncache. See 1152 * tcp_syncache.c for details. 1153 * 1154 * The ISNs in SYN packets must be monotonic; TIME_WAIT recycling 1155 * depends on this property. In addition, these ISNs should be 1156 * unguessable so as to prevent connection hijacking. To satisfy 1157 * the requirements of this situation, the algorithm outlined in 1158 * RFC 1948 is used to generate sequence numbers. 1159 * 1160 * Implementation details: 1161 * 1162 * Time is based off the system timer, and is corrected so that it 1163 * increases by one megabyte per second. This allows for proper 1164 * recycling on high speed LANs while still leaving over an hour 1165 * before rollover. 1166 * 1167 * net.inet.tcp.isn_reseed_interval controls the number of seconds 1168 * between seeding of isn_secret. This is normally set to zero, 1169 * as reseeding should not be necessary. 1170 * 1171 */ 1172 1173 #define ISN_BYTES_PER_SECOND 1048576 1174 1175 u_char isn_secret[32]; 1176 int isn_last_reseed; 1177 MD5_CTX isn_ctx; 1178 1179 tcp_seq 1180 tcp_new_isn(tp) 1181 struct tcpcb *tp; 1182 { 1183 u_int32_t md5_buffer[4]; 1184 tcp_seq new_isn; 1185 1186 /* Seed if this is the first use, reseed if requested. */ 1187 if ((isn_last_reseed == 0) || ((tcp_isn_reseed_interval > 0) && 1188 (((u_int)isn_last_reseed + (u_int)tcp_isn_reseed_interval*hz) 1189 < (u_int)ticks))) { 1190 read_random_unlimited(&isn_secret, sizeof(isn_secret)); 1191 isn_last_reseed = ticks; 1192 } 1193 1194 /* Compute the md5 hash and return the ISN. */ 1195 MD5Init(&isn_ctx); 1196 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_fport, sizeof(u_short)); 1197 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_lport, sizeof(u_short)); 1198 #ifdef INET6 1199 if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0) { 1200 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_faddr, 1201 sizeof(struct in6_addr)); 1202 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_laddr, 1203 sizeof(struct in6_addr)); 1204 } else 1205 #endif 1206 { 1207 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_faddr, 1208 sizeof(struct in_addr)); 1209 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_laddr, 1210 sizeof(struct in_addr)); 1211 } 1212 MD5Update(&isn_ctx, (u_char *) &isn_secret, sizeof(isn_secret)); 1213 MD5Final((u_char *) &md5_buffer, &isn_ctx); 1214 new_isn = (tcp_seq) md5_buffer[0]; 1215 new_isn += ticks * (ISN_BYTES_PER_SECOND / hz); 1216 return new_isn; 1217 } 1218 1219 /* 1220 * When a source quench is received, close congestion window 1221 * to one segment. We will gradually open it again as we proceed. 1222 */ 1223 void 1224 tcp_quench(inp, errno) 1225 struct inpcb *inp; 1226 int errno; 1227 { 1228 struct tcpcb *tp = intotcpcb(inp); 1229 1230 if (tp) 1231 tp->snd_cwnd = tp->t_maxseg; 1232 } 1233 1234 /* 1235 * When a specific ICMP unreachable message is received and the 1236 * connection state is SYN-SENT, drop the connection. This behavior 1237 * is controlled by the icmp_may_rst sysctl. 1238 */ 1239 void 1240 tcp_drop_syn_sent(inp, errno) 1241 struct inpcb *inp; 1242 int errno; 1243 { 1244 struct tcpcb *tp = intotcpcb(inp); 1245 1246 if (tp && tp->t_state == TCPS_SYN_SENT) 1247 tcp_drop(tp, errno); 1248 } 1249 1250 /* 1251 * When `need fragmentation' ICMP is received, update our idea of the MSS 1252 * based on the new value in the route. Also nudge TCP to send something, 1253 * since we know the packet we just sent was dropped. 1254 * This duplicates some code in the tcp_mss() function in tcp_input.c. 1255 */ 1256 void 1257 tcp_mtudisc(inp, errno) 1258 struct inpcb *inp; 1259 int errno; 1260 { 1261 struct tcpcb *tp = intotcpcb(inp); 1262 struct rtentry *rt; 1263 struct rmxp_tao *taop; 1264 struct socket *so = inp->inp_socket; 1265 int offered; 1266 int mss; 1267 #ifdef INET6 1268 int isipv6 = (tp->t_inpcb->inp_vflag & INP_IPV6) != 0; 1269 #endif /* INET6 */ 1270 1271 if (tp) { 1272 #ifdef INET6 1273 if (isipv6) 1274 rt = tcp_rtlookup6(&inp->inp_inc); 1275 else 1276 #endif /* INET6 */ 1277 rt = tcp_rtlookup(&inp->inp_inc); 1278 if (!rt || !rt->rt_rmx.rmx_mtu) { 1279 tp->t_maxopd = tp->t_maxseg = 1280 #ifdef INET6 1281 isipv6 ? tcp_v6mssdflt : 1282 #endif /* INET6 */ 1283 tcp_mssdflt; 1284 return; 1285 } 1286 taop = rmx_taop(rt->rt_rmx); 1287 offered = taop->tao_mssopt; 1288 mss = rt->rt_rmx.rmx_mtu - 1289 #ifdef INET6 1290 (isipv6 ? 1291 sizeof(struct ip6_hdr) + sizeof(struct tcphdr) : 1292 #endif /* INET6 */ 1293 sizeof(struct tcpiphdr) 1294 #ifdef INET6 1295 ) 1296 #endif /* INET6 */ 1297 ; 1298 1299 if (offered) 1300 mss = min(mss, offered); 1301 /* 1302 * XXX - The above conditional probably violates the TCP 1303 * spec. The problem is that, since we don't know the 1304 * other end's MSS, we are supposed to use a conservative 1305 * default. But, if we do that, then MTU discovery will 1306 * never actually take place, because the conservative 1307 * default is much less than the MTUs typically seen 1308 * on the Internet today. For the moment, we'll sweep 1309 * this under the carpet. 1310 * 1311 * The conservative default might not actually be a problem 1312 * if the only case this occurs is when sending an initial 1313 * SYN with options and data to a host we've never talked 1314 * to before. Then, they will reply with an MSS value which 1315 * will get recorded and the new parameters should get 1316 * recomputed. For Further Study. 1317 */ 1318 if (tp->t_maxopd <= mss) 1319 return; 1320 tp->t_maxopd = mss; 1321 1322 if ((tp->t_flags & (TF_REQ_TSTMP|TF_NOOPT)) == TF_REQ_TSTMP && 1323 (tp->t_flags & TF_RCVD_TSTMP) == TF_RCVD_TSTMP) 1324 mss -= TCPOLEN_TSTAMP_APPA; 1325 if ((tp->t_flags & (TF_REQ_CC|TF_NOOPT)) == TF_REQ_CC && 1326 (tp->t_flags & TF_RCVD_CC) == TF_RCVD_CC) 1327 mss -= TCPOLEN_CC_APPA; 1328 #if (MCLBYTES & (MCLBYTES - 1)) == 0 1329 if (mss > MCLBYTES) 1330 mss &= ~(MCLBYTES-1); 1331 #else 1332 if (mss > MCLBYTES) 1333 mss = mss / MCLBYTES * MCLBYTES; 1334 #endif 1335 if (so->so_snd.sb_hiwat < mss) 1336 mss = so->so_snd.sb_hiwat; 1337 1338 tp->t_maxseg = mss; 1339 1340 tcpstat.tcps_mturesent++; 1341 tp->t_rtttime = 0; 1342 tp->snd_nxt = tp->snd_una; 1343 tcp_output(tp); 1344 } 1345 } 1346 1347 /* 1348 * Look-up the routing entry to the peer of this inpcb. If no route 1349 * is found and it cannot be allocated the return NULL. This routine 1350 * is called by TCP routines that access the rmx structure and by tcp_mss 1351 * to get the interface MTU. 1352 */ 1353 struct rtentry * 1354 tcp_rtlookup(inc) 1355 struct in_conninfo *inc; 1356 { 1357 struct route *ro; 1358 struct rtentry *rt; 1359 1360 ro = &inc->inc_route; 1361 rt = ro->ro_rt; 1362 if (rt == NULL || !(rt->rt_flags & RTF_UP)) { 1363 /* No route yet, so try to acquire one */ 1364 if (inc->inc_faddr.s_addr != INADDR_ANY) { 1365 ro->ro_dst.sa_family = AF_INET; 1366 ro->ro_dst.sa_len = sizeof(struct sockaddr_in); 1367 ((struct sockaddr_in *) &ro->ro_dst)->sin_addr = 1368 inc->inc_faddr; 1369 rtalloc(ro); 1370 rt = ro->ro_rt; 1371 } 1372 } 1373 return rt; 1374 } 1375 1376 #ifdef INET6 1377 struct rtentry * 1378 tcp_rtlookup6(inc) 1379 struct in_conninfo *inc; 1380 { 1381 struct route_in6 *ro6; 1382 struct rtentry *rt; 1383 1384 ro6 = &inc->inc6_route; 1385 rt = ro6->ro_rt; 1386 if (rt == NULL || !(rt->rt_flags & RTF_UP)) { 1387 /* No route yet, so try to acquire one */ 1388 if (!IN6_IS_ADDR_UNSPECIFIED(&inc->inc6_faddr)) { 1389 ro6->ro_dst.sin6_family = AF_INET6; 1390 ro6->ro_dst.sin6_len = sizeof(struct sockaddr_in6); 1391 ro6->ro_dst.sin6_addr = inc->inc6_faddr; 1392 rtalloc((struct route *)ro6); 1393 rt = ro6->ro_rt; 1394 } 1395 } 1396 return rt; 1397 } 1398 #endif /* INET6 */ 1399 1400 #ifdef IPSEC 1401 /* compute ESP/AH header size for TCP, including outer IP header. */ 1402 size_t 1403 ipsec_hdrsiz_tcp(tp) 1404 struct tcpcb *tp; 1405 { 1406 struct inpcb *inp; 1407 struct mbuf *m; 1408 size_t hdrsiz; 1409 struct ip *ip; 1410 #ifdef INET6 1411 struct ip6_hdr *ip6; 1412 #endif /* INET6 */ 1413 struct tcphdr *th; 1414 1415 if ((tp == NULL) || ((inp = tp->t_inpcb) == NULL)) 1416 return 0; 1417 MGETHDR(m, M_DONTWAIT, MT_DATA); 1418 if (!m) 1419 return 0; 1420 1421 #ifdef INET6 1422 if ((inp->inp_vflag & INP_IPV6) != 0) { 1423 ip6 = mtod(m, struct ip6_hdr *); 1424 th = (struct tcphdr *)(ip6 + 1); 1425 m->m_pkthdr.len = m->m_len = 1426 sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 1427 tcp_fillheaders(tp, ip6, th); 1428 hdrsiz = ipsec6_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp); 1429 } else 1430 #endif /* INET6 */ 1431 { 1432 ip = mtod(m, struct ip *); 1433 th = (struct tcphdr *)(ip + 1); 1434 m->m_pkthdr.len = m->m_len = sizeof(struct tcpiphdr); 1435 tcp_fillheaders(tp, ip, th); 1436 hdrsiz = ipsec4_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp); 1437 } 1438 1439 m_free(m); 1440 return hdrsiz; 1441 } 1442 #endif /*IPSEC*/ 1443 1444 /* 1445 * Return a pointer to the cached information about the remote host. 1446 * The cached information is stored in the protocol specific part of 1447 * the route metrics. 1448 */ 1449 struct rmxp_tao * 1450 tcp_gettaocache(inc) 1451 struct in_conninfo *inc; 1452 { 1453 struct rtentry *rt; 1454 1455 #ifdef INET6 1456 if (inc->inc_isipv6) 1457 rt = tcp_rtlookup6(inc); 1458 else 1459 #endif /* INET6 */ 1460 rt = tcp_rtlookup(inc); 1461 1462 /* Make sure this is a host route and is up. */ 1463 if (rt == NULL || 1464 (rt->rt_flags & (RTF_UP|RTF_HOST)) != (RTF_UP|RTF_HOST)) 1465 return NULL; 1466 1467 return rmx_taop(rt->rt_rmx); 1468 } 1469 1470 /* 1471 * Clear all the TAO cache entries, called from tcp_init. 1472 * 1473 * XXX 1474 * This routine is just an empty one, because we assume that the routing 1475 * routing tables are initialized at the same time when TCP, so there is 1476 * nothing in the cache left over. 1477 */ 1478 static void 1479 tcp_cleartaocache() 1480 { 1481 } 1482 1483 /* 1484 * TCP BANDWIDTH DELAY PRODUCT WINDOW LIMITING 1485 * 1486 * This code attempts to calculate the bandwidth-delay product as a 1487 * means of determining the optimal window size to maximize bandwidth, 1488 * minimize RTT, and avoid the over-allocation of buffers on interfaces and 1489 * routers. This code also does a fairly good job keeping RTTs in check 1490 * across slow links like modems. We implement an algorithm which is very 1491 * similar (but not meant to be) TCP/Vegas. The code operates on the 1492 * transmitter side of a TCP connection and so only effects the transmit 1493 * side of the connection. 1494 * 1495 * BACKGROUND: TCP makes no provision for the management of buffer space 1496 * at the end points or at the intermediate routers and switches. A TCP 1497 * stream, whether using NewReno or not, will eventually buffer as 1498 * many packets as it is able and the only reason this typically works is 1499 * due to the fairly small default buffers made available for a connection 1500 * (typicaly 16K or 32K). As machines use larger windows and/or window 1501 * scaling it is now fairly easy for even a single TCP connection to blow-out 1502 * all available buffer space not only on the local interface, but on 1503 * intermediate routers and switches as well. NewReno makes a misguided 1504 * attempt to 'solve' this problem by waiting for an actual failure to occur, 1505 * then backing off, then steadily increasing the window again until another 1506 * failure occurs, ad-infinitum. This results in terrible oscillation that 1507 * is only made worse as network loads increase and the idea of intentionally 1508 * blowing out network buffers is, frankly, a terrible way to manage network 1509 * resources. 1510 * 1511 * It is far better to limit the transmit window prior to the failure 1512 * condition being achieved. There are two general ways to do this: First 1513 * you can 'scan' through different transmit window sizes and locate the 1514 * point where the RTT stops increasing, indicating that you have filled the 1515 * pipe, then scan backwards until you note that RTT stops decreasing, then 1516 * repeat ad-infinitum. This method works in principle but has severe 1517 * implementation issues due to RTT variances, timer granularity, and 1518 * instability in the algorithm which can lead to many false positives and 1519 * create oscillations as well as interact badly with other TCP streams 1520 * implementing the same algorithm. 1521 * 1522 * The second method is to limit the window to the bandwidth delay product 1523 * of the link. This is the method we implement. RTT variances and our 1524 * own manipulation of the congestion window, bwnd, can potentially 1525 * destabilize the algorithm. For this reason we have to stabilize the 1526 * elements used to calculate the window. We do this by using the minimum 1527 * observed RTT, the long term average of the observed bandwidth, and 1528 * by adding two segments worth of slop. It isn't perfect but it is able 1529 * to react to changing conditions and gives us a very stable basis on 1530 * which to extend the algorithm. 1531 */ 1532 void 1533 tcp_xmit_bandwidth_limit(struct tcpcb *tp, tcp_seq ack_seq) 1534 { 1535 u_long bw; 1536 u_long bwnd; 1537 int save_ticks; 1538 1539 /* 1540 * If inflight_enable is disabled in the middle of a tcp connection, 1541 * make sure snd_bwnd is effectively disabled. 1542 */ 1543 if (tcp_inflight_enable == 0) { 1544 tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 1545 tp->snd_bandwidth = 0; 1546 return; 1547 } 1548 1549 /* 1550 * Figure out the bandwidth. Due to the tick granularity this 1551 * is a very rough number and it MUST be averaged over a fairly 1552 * long period of time. XXX we need to take into account a link 1553 * that is not using all available bandwidth, but for now our 1554 * slop will ramp us up if this case occurs and the bandwidth later 1555 * increases. 1556 * 1557 * Note: if ticks rollover 'bw' may wind up negative. We must 1558 * effectively reset t_bw_rtttime for this case. 1559 */ 1560 save_ticks = ticks; 1561 if ((u_int)(save_ticks - tp->t_bw_rtttime) < 1) 1562 return; 1563 1564 bw = (int64_t)(ack_seq - tp->t_bw_rtseq) * hz / 1565 (save_ticks - tp->t_bw_rtttime); 1566 tp->t_bw_rtttime = save_ticks; 1567 tp->t_bw_rtseq = ack_seq; 1568 if (tp->t_bw_rtttime == 0 || (int)bw < 0) 1569 return; 1570 bw = ((int64_t)tp->snd_bandwidth * 15 + bw) >> 4; 1571 1572 tp->snd_bandwidth = bw; 1573 1574 /* 1575 * Calculate the semi-static bandwidth delay product, plus two maximal 1576 * segments. The additional slop puts us squarely in the sweet 1577 * spot and also handles the bandwidth run-up case. Without the 1578 * slop we could be locking ourselves into a lower bandwidth. 1579 * 1580 * Situations Handled: 1581 * (1) Prevents over-queueing of packets on LANs, especially on 1582 * high speed LANs, allowing larger TCP buffers to be 1583 * specified, and also does a good job preventing 1584 * over-queueing of packets over choke points like modems 1585 * (at least for the transmit side). 1586 * 1587 * (2) Is able to handle changing network loads (bandwidth 1588 * drops so bwnd drops, bandwidth increases so bwnd 1589 * increases). 1590 * 1591 * (3) Theoretically should stabilize in the face of multiple 1592 * connections implementing the same algorithm (this may need 1593 * a little work). 1594 * 1595 * (4) Stability value (defaults to 20 = 2 maximal packets) can 1596 * be adjusted with a sysctl but typically only needs to be on 1597 * very slow connections. A value no smaller then 5 should 1598 * be used, but only reduce this default if you have no other 1599 * choice. 1600 */ 1601 #define USERTT ((tp->t_srtt + tp->t_rttbest) / 2) 1602 bwnd = (int64_t)bw * USERTT / (hz << TCP_RTT_SHIFT) + tcp_inflight_stab * (int)tp->t_maxseg / 10; 1603 #undef USERTT 1604 1605 if (tcp_inflight_debug > 0) { 1606 static int ltime; 1607 if ((u_int)(ticks - ltime) >= hz / tcp_inflight_debug) { 1608 ltime = ticks; 1609 printf("%p bw %ld rttbest %d srtt %d bwnd %ld\n", 1610 tp, 1611 bw, 1612 tp->t_rttbest, 1613 tp->t_srtt, 1614 bwnd 1615 ); 1616 } 1617 } 1618 if ((long)bwnd < tcp_inflight_min) 1619 bwnd = tcp_inflight_min; 1620 if (bwnd > tcp_inflight_max) 1621 bwnd = tcp_inflight_max; 1622 if ((long)bwnd < tp->t_maxseg * 2) 1623 bwnd = tp->t_maxseg * 2; 1624 tp->snd_bwnd = bwnd; 1625 } 1626 1627