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 1.9 2003/11/08 07:57:51 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/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 tcp_thread_init(); 262 } 263 264 /* 265 * Fill in the IP and TCP headers for an outgoing packet, given the tcpcb. 266 * tcp_template used to store this data in mbufs, but we now recopy it out 267 * of the tcpcb each time to conserve mbufs. 268 */ 269 void 270 tcp_fillheaders(tp, ip_ptr, tcp_ptr) 271 struct tcpcb *tp; 272 void *ip_ptr; 273 void *tcp_ptr; 274 { 275 struct inpcb *inp = tp->t_inpcb; 276 struct tcphdr *tcp_hdr = (struct tcphdr *)tcp_ptr; 277 278 #ifdef INET6 279 if ((inp->inp_vflag & INP_IPV6) != 0) { 280 struct ip6_hdr *ip6; 281 282 ip6 = (struct ip6_hdr *)ip_ptr; 283 ip6->ip6_flow = (ip6->ip6_flow & ~IPV6_FLOWINFO_MASK) | 284 (inp->in6p_flowinfo & IPV6_FLOWINFO_MASK); 285 ip6->ip6_vfc = (ip6->ip6_vfc & ~IPV6_VERSION_MASK) | 286 (IPV6_VERSION & IPV6_VERSION_MASK); 287 ip6->ip6_nxt = IPPROTO_TCP; 288 ip6->ip6_plen = sizeof(struct tcphdr); 289 ip6->ip6_src = inp->in6p_laddr; 290 ip6->ip6_dst = inp->in6p_faddr; 291 tcp_hdr->th_sum = 0; 292 } else 293 #endif 294 { 295 struct ip *ip = (struct ip *) ip_ptr; 296 297 ip->ip_vhl = IP_VHL_BORING; 298 ip->ip_tos = 0; 299 ip->ip_len = 0; 300 ip->ip_id = 0; 301 ip->ip_off = 0; 302 ip->ip_ttl = 0; 303 ip->ip_sum = 0; 304 ip->ip_p = IPPROTO_TCP; 305 ip->ip_src = inp->inp_laddr; 306 ip->ip_dst = inp->inp_faddr; 307 tcp_hdr->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr, 308 htons(sizeof(struct tcphdr) + IPPROTO_TCP)); 309 } 310 311 tcp_hdr->th_sport = inp->inp_lport; 312 tcp_hdr->th_dport = inp->inp_fport; 313 tcp_hdr->th_seq = 0; 314 tcp_hdr->th_ack = 0; 315 tcp_hdr->th_x2 = 0; 316 tcp_hdr->th_off = 5; 317 tcp_hdr->th_flags = 0; 318 tcp_hdr->th_win = 0; 319 tcp_hdr->th_urp = 0; 320 } 321 322 /* 323 * Create template to be used to send tcp packets on a connection. 324 * Allocates an mbuf and fills in a skeletal tcp/ip header. The only 325 * use for this function is in keepalives, which use tcp_respond. 326 */ 327 struct tcptemp * 328 tcp_maketemplate(tp) 329 struct tcpcb *tp; 330 { 331 struct mbuf *m; 332 struct tcptemp *n; 333 334 m = m_get(M_DONTWAIT, MT_HEADER); 335 if (m == NULL) 336 return (0); 337 m->m_len = sizeof(struct tcptemp); 338 n = mtod(m, struct tcptemp *); 339 340 tcp_fillheaders(tp, (void *)&n->tt_ipgen, (void *)&n->tt_t); 341 return (n); 342 } 343 344 /* 345 * Send a single message to the TCP at address specified by 346 * the given TCP/IP header. If m == 0, then we make a copy 347 * of the tcpiphdr at ti and send directly to the addressed host. 348 * This is used to force keep alive messages out using the TCP 349 * template for a connection. If flags are given then we send 350 * a message back to the TCP which originated the * segment ti, 351 * and discard the mbuf containing it and any other attached mbufs. 352 * 353 * In any case the ack and sequence number of the transmitted 354 * segment are as specified by the parameters. 355 * 356 * NOTE: If m != NULL, then ti must point to *inside* the mbuf. 357 */ 358 void 359 tcp_respond(tp, ipgen, th, m, ack, seq, flags) 360 struct tcpcb *tp; 361 void *ipgen; 362 struct tcphdr *th; 363 struct mbuf *m; 364 tcp_seq ack, seq; 365 int flags; 366 { 367 int tlen; 368 int win = 0; 369 struct route *ro = 0; 370 struct route sro; 371 struct ip *ip; 372 struct tcphdr *nth; 373 #ifdef INET6 374 struct route_in6 *ro6 = 0; 375 struct route_in6 sro6; 376 struct ip6_hdr *ip6; 377 int isipv6; 378 #endif /* INET6 */ 379 int ipflags = 0; 380 381 #ifdef INET6 382 isipv6 = IP_VHL_V(((struct ip *)ipgen)->ip_vhl) == 6; 383 ip6 = ipgen; 384 #endif /* INET6 */ 385 ip = ipgen; 386 387 if (tp) { 388 if (!(flags & TH_RST)) { 389 win = sbspace(&tp->t_inpcb->inp_socket->so_rcv); 390 if (win > (long)TCP_MAXWIN << tp->rcv_scale) 391 win = (long)TCP_MAXWIN << tp->rcv_scale; 392 } 393 #ifdef INET6 394 if (isipv6) 395 ro6 = &tp->t_inpcb->in6p_route; 396 else 397 #endif /* INET6 */ 398 ro = &tp->t_inpcb->inp_route; 399 } else { 400 #ifdef INET6 401 if (isipv6) { 402 ro6 = &sro6; 403 bzero(ro6, sizeof *ro6); 404 } else 405 #endif /* INET6 */ 406 { 407 ro = &sro; 408 bzero(ro, sizeof *ro); 409 } 410 } 411 if (m == 0) { 412 m = m_gethdr(M_DONTWAIT, MT_HEADER); 413 if (m == NULL) 414 return; 415 tlen = 0; 416 m->m_data += max_linkhdr; 417 #ifdef INET6 418 if (isipv6) { 419 bcopy((caddr_t)ip6, mtod(m, caddr_t), 420 sizeof(struct ip6_hdr)); 421 ip6 = mtod(m, struct ip6_hdr *); 422 nth = (struct tcphdr *)(ip6 + 1); 423 } else 424 #endif /* INET6 */ 425 { 426 bcopy((caddr_t)ip, mtod(m, caddr_t), sizeof(struct ip)); 427 ip = mtod(m, struct ip *); 428 nth = (struct tcphdr *)(ip + 1); 429 } 430 bcopy((caddr_t)th, (caddr_t)nth, sizeof(struct tcphdr)); 431 flags = TH_ACK; 432 } else { 433 m_freem(m->m_next); 434 m->m_next = 0; 435 m->m_data = (caddr_t)ipgen; 436 /* m_len is set later */ 437 tlen = 0; 438 #define xchg(a,b,type) { type t; t=a; a=b; b=t; } 439 #ifdef INET6 440 if (isipv6) { 441 xchg(ip6->ip6_dst, ip6->ip6_src, struct in6_addr); 442 nth = (struct tcphdr *)(ip6 + 1); 443 } else 444 #endif /* INET6 */ 445 { 446 xchg(ip->ip_dst.s_addr, ip->ip_src.s_addr, n_long); 447 nth = (struct tcphdr *)(ip + 1); 448 } 449 if (th != nth) { 450 /* 451 * this is usually a case when an extension header 452 * exists between the IPv6 header and the 453 * TCP header. 454 */ 455 nth->th_sport = th->th_sport; 456 nth->th_dport = th->th_dport; 457 } 458 xchg(nth->th_dport, nth->th_sport, n_short); 459 #undef xchg 460 } 461 #ifdef INET6 462 if (isipv6) { 463 ip6->ip6_flow = 0; 464 ip6->ip6_vfc = IPV6_VERSION; 465 ip6->ip6_nxt = IPPROTO_TCP; 466 ip6->ip6_plen = htons((u_short)(sizeof (struct tcphdr) + 467 tlen)); 468 tlen += sizeof (struct ip6_hdr) + sizeof (struct tcphdr); 469 } else 470 #endif 471 { 472 tlen += sizeof (struct tcpiphdr); 473 ip->ip_len = tlen; 474 ip->ip_ttl = ip_defttl; 475 } 476 m->m_len = tlen; 477 m->m_pkthdr.len = tlen; 478 m->m_pkthdr.rcvif = (struct ifnet *) 0; 479 nth->th_seq = htonl(seq); 480 nth->th_ack = htonl(ack); 481 nth->th_x2 = 0; 482 nth->th_off = sizeof (struct tcphdr) >> 2; 483 nth->th_flags = flags; 484 if (tp) 485 nth->th_win = htons((u_short) (win >> tp->rcv_scale)); 486 else 487 nth->th_win = htons((u_short)win); 488 nth->th_urp = 0; 489 #ifdef INET6 490 if (isipv6) { 491 nth->th_sum = 0; 492 nth->th_sum = in6_cksum(m, IPPROTO_TCP, 493 sizeof(struct ip6_hdr), 494 tlen - sizeof(struct ip6_hdr)); 495 ip6->ip6_hlim = in6_selecthlim(tp ? tp->t_inpcb : NULL, 496 ro6 && ro6->ro_rt ? 497 ro6->ro_rt->rt_ifp : 498 NULL); 499 } else 500 #endif /* INET6 */ 501 { 502 nth->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr, 503 htons((u_short)(tlen - sizeof(struct ip) + ip->ip_p))); 504 m->m_pkthdr.csum_flags = CSUM_TCP; 505 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 506 } 507 #ifdef TCPDEBUG 508 if (tp == NULL || (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) 509 tcp_trace(TA_OUTPUT, 0, tp, mtod(m, void *), th, 0); 510 #endif 511 #ifdef INET6 512 if (isipv6) { 513 (void)ip6_output(m, NULL, ro6, ipflags, NULL, NULL, 514 tp ? tp->t_inpcb : NULL); 515 if (ro6 == &sro6 && ro6->ro_rt) { 516 RTFREE(ro6->ro_rt); 517 ro6->ro_rt = NULL; 518 } 519 } else 520 #endif /* INET6 */ 521 { 522 (void) ip_output(m, NULL, ro, ipflags, NULL, tp ? tp->t_inpcb : NULL); 523 if (ro == &sro && ro->ro_rt) { 524 RTFREE(ro->ro_rt); 525 ro->ro_rt = NULL; 526 } 527 } 528 } 529 530 /* 531 * Create a new TCP control block, making an 532 * empty reassembly queue and hooking it to the argument 533 * protocol control block. The `inp' parameter must have 534 * come from the zone allocator set up in tcp_init(). 535 */ 536 struct tcpcb * 537 tcp_newtcpcb(inp) 538 struct inpcb *inp; 539 { 540 struct inp_tp *it; 541 struct tcpcb *tp; 542 #ifdef INET6 543 int isipv6 = (inp->inp_vflag & INP_IPV6) != 0; 544 #endif /* INET6 */ 545 546 it = (struct inp_tp *)inp; 547 tp = &it->tcb; 548 bzero((char *) tp, sizeof(struct tcpcb)); 549 LIST_INIT(&tp->t_segq); 550 tp->t_maxseg = tp->t_maxopd = 551 #ifdef INET6 552 isipv6 ? tcp_v6mssdflt : 553 #endif /* INET6 */ 554 tcp_mssdflt; 555 556 /* Set up our timeouts. */ 557 callout_init(tp->tt_rexmt = &it->inp_tp_rexmt); 558 callout_init(tp->tt_persist = &it->inp_tp_persist); 559 callout_init(tp->tt_keep = &it->inp_tp_keep); 560 callout_init(tp->tt_2msl = &it->inp_tp_2msl); 561 callout_init(tp->tt_delack = &it->inp_tp_delack); 562 563 if (tcp_do_rfc1323) 564 tp->t_flags = (TF_REQ_SCALE|TF_REQ_TSTMP); 565 if (tcp_do_rfc1644) 566 tp->t_flags |= TF_REQ_CC; 567 tp->t_inpcb = inp; /* XXX */ 568 /* 569 * Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no 570 * rtt estimate. Set rttvar so that srtt + 4 * rttvar gives 571 * reasonable initial retransmit time. 572 */ 573 tp->t_srtt = TCPTV_SRTTBASE; 574 tp->t_rttvar = ((TCPTV_RTOBASE - TCPTV_SRTTBASE) << TCP_RTTVAR_SHIFT) / 4; 575 tp->t_rttmin = tcp_rexmit_min; 576 tp->t_rxtcur = TCPTV_RTOBASE; 577 tp->snd_cwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 578 tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 579 tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT; 580 tp->t_rcvtime = ticks; 581 tp->t_bw_rtttime = ticks; 582 /* 583 * IPv4 TTL initialization is necessary for an IPv6 socket as well, 584 * because the socket may be bound to an IPv6 wildcard address, 585 * which may match an IPv4-mapped IPv6 address. 586 */ 587 inp->inp_ip_ttl = ip_defttl; 588 inp->inp_ppcb = (caddr_t)tp; 589 return (tp); /* XXX */ 590 } 591 592 /* 593 * Drop a TCP connection, reporting 594 * the specified error. If connection is synchronized, 595 * then send a RST to peer. 596 */ 597 struct tcpcb * 598 tcp_drop(tp, errno) 599 struct tcpcb *tp; 600 int errno; 601 { 602 struct socket *so = tp->t_inpcb->inp_socket; 603 604 if (TCPS_HAVERCVDSYN(tp->t_state)) { 605 tp->t_state = TCPS_CLOSED; 606 (void) tcp_output(tp); 607 tcpstat.tcps_drops++; 608 } else 609 tcpstat.tcps_conndrops++; 610 if (errno == ETIMEDOUT && tp->t_softerror) 611 errno = tp->t_softerror; 612 so->so_error = errno; 613 return (tcp_close(tp)); 614 } 615 616 /* 617 * Close a TCP control block: 618 * discard all space held by the tcp 619 * discard internet protocol block 620 * wake up any sleepers 621 */ 622 struct tcpcb * 623 tcp_close(tp) 624 struct tcpcb *tp; 625 { 626 struct tseg_qent *q; 627 struct inpcb *inp = tp->t_inpcb; 628 struct socket *so = inp->inp_socket; 629 #ifdef INET6 630 int isipv6 = (inp->inp_vflag & INP_IPV6) != 0; 631 #endif /* INET6 */ 632 struct rtentry *rt; 633 int dosavessthresh; 634 635 /* 636 * Make sure that all of our timers are stopped before we 637 * delete the PCB. 638 */ 639 callout_stop(tp->tt_rexmt); 640 callout_stop(tp->tt_persist); 641 callout_stop(tp->tt_keep); 642 callout_stop(tp->tt_2msl); 643 callout_stop(tp->tt_delack); 644 645 /* 646 * If we got enough samples through the srtt filter, 647 * save the rtt and rttvar in the routing entry. 648 * 'Enough' is arbitrarily defined as the 16 samples. 649 * 16 samples is enough for the srtt filter to converge 650 * to within 5% of the correct value; fewer samples and 651 * we could save a very bogus rtt. 652 * 653 * Don't update the default route's characteristics and don't 654 * update anything that the user "locked". 655 */ 656 if (tp->t_rttupdated >= 16) { 657 u_long i = 0; 658 #ifdef INET6 659 if (isipv6) { 660 struct sockaddr_in6 *sin6; 661 662 if ((rt = inp->in6p_route.ro_rt) == NULL) 663 goto no_valid_rt; 664 sin6 = (struct sockaddr_in6 *)rt_key(rt); 665 if (IN6_IS_ADDR_UNSPECIFIED(&sin6->sin6_addr)) 666 goto no_valid_rt; 667 } 668 else 669 #endif /* INET6 */ 670 if ((rt = inp->inp_route.ro_rt) == NULL || 671 ((struct sockaddr_in *)rt_key(rt))->sin_addr.s_addr 672 == INADDR_ANY) 673 goto no_valid_rt; 674 675 if ((rt->rt_rmx.rmx_locks & RTV_RTT) == 0) { 676 i = tp->t_srtt * 677 (RTM_RTTUNIT / (hz * TCP_RTT_SCALE)); 678 if (rt->rt_rmx.rmx_rtt && i) 679 /* 680 * filter this update to half the old & half 681 * the new values, converting scale. 682 * See route.h and tcp_var.h for a 683 * description of the scaling constants. 684 */ 685 rt->rt_rmx.rmx_rtt = 686 (rt->rt_rmx.rmx_rtt + i) / 2; 687 else 688 rt->rt_rmx.rmx_rtt = i; 689 tcpstat.tcps_cachedrtt++; 690 } 691 if ((rt->rt_rmx.rmx_locks & RTV_RTTVAR) == 0) { 692 i = tp->t_rttvar * 693 (RTM_RTTUNIT / (hz * TCP_RTTVAR_SCALE)); 694 if (rt->rt_rmx.rmx_rttvar && i) 695 rt->rt_rmx.rmx_rttvar = 696 (rt->rt_rmx.rmx_rttvar + i) / 2; 697 else 698 rt->rt_rmx.rmx_rttvar = i; 699 tcpstat.tcps_cachedrttvar++; 700 } 701 /* 702 * The old comment here said: 703 * update the pipelimit (ssthresh) if it has been updated 704 * already or if a pipesize was specified & the threshhold 705 * got below half the pipesize. I.e., wait for bad news 706 * before we start updating, then update on both good 707 * and bad news. 708 * 709 * But we want to save the ssthresh even if no pipesize is 710 * specified explicitly in the route, because such 711 * connections still have an implicit pipesize specified 712 * by the global tcp_sendspace. In the absence of a reliable 713 * way to calculate the pipesize, it will have to do. 714 */ 715 i = tp->snd_ssthresh; 716 if (rt->rt_rmx.rmx_sendpipe != 0) 717 dosavessthresh = (i < rt->rt_rmx.rmx_sendpipe / 2); 718 else 719 dosavessthresh = (i < so->so_snd.sb_hiwat / 2); 720 if (((rt->rt_rmx.rmx_locks & RTV_SSTHRESH) == 0 && 721 i != 0 && rt->rt_rmx.rmx_ssthresh != 0) 722 || dosavessthresh) { 723 /* 724 * convert the limit from user data bytes to 725 * packets then to packet data bytes. 726 */ 727 i = (i + tp->t_maxseg / 2) / tp->t_maxseg; 728 if (i < 2) 729 i = 2; 730 i *= (u_long)(tp->t_maxseg + 731 #ifdef INET6 732 (isipv6 ? sizeof (struct ip6_hdr) + 733 sizeof (struct tcphdr) : 734 #endif 735 sizeof (struct tcpiphdr) 736 #ifdef INET6 737 ) 738 #endif 739 ); 740 if (rt->rt_rmx.rmx_ssthresh) 741 rt->rt_rmx.rmx_ssthresh = 742 (rt->rt_rmx.rmx_ssthresh + i) / 2; 743 else 744 rt->rt_rmx.rmx_ssthresh = i; 745 tcpstat.tcps_cachedssthresh++; 746 } 747 } 748 no_valid_rt: 749 /* free the reassembly queue, if any */ 750 while((q = LIST_FIRST(&tp->t_segq)) != NULL) { 751 LIST_REMOVE(q, tqe_q); 752 m_freem(q->tqe_m); 753 FREE(q, M_TSEGQ); 754 } 755 inp->inp_ppcb = NULL; 756 soisdisconnected(so); 757 #ifdef INET6 758 if (INP_CHECK_SOCKAF(so, AF_INET6)) 759 in6_pcbdetach(inp); 760 else 761 #endif /* INET6 */ 762 in_pcbdetach(inp); 763 tcpstat.tcps_closed++; 764 return ((struct tcpcb *)0); 765 } 766 767 void 768 tcp_drain() 769 { 770 if (do_tcpdrain) 771 { 772 struct inpcb *inpb; 773 struct tcpcb *tcpb; 774 struct tseg_qent *te; 775 776 /* 777 * Walk the tcpbs, if existing, and flush the reassembly queue, 778 * if there is one... 779 * XXX: The "Net/3" implementation doesn't imply that the TCP 780 * reassembly queue should be flushed, but in a situation 781 * where we're really low on mbufs, this is potentially 782 * usefull. 783 */ 784 LIST_FOREACH(inpb, tcbinfo.listhead, inp_list) { 785 if ((tcpb = intotcpcb(inpb))) { 786 while ((te = LIST_FIRST(&tcpb->t_segq)) 787 != NULL) { 788 LIST_REMOVE(te, tqe_q); 789 m_freem(te->tqe_m); 790 FREE(te, M_TSEGQ); 791 } 792 } 793 } 794 795 } 796 } 797 798 /* 799 * Notify a tcp user of an asynchronous error; 800 * store error as soft error, but wake up user 801 * (for now, won't do anything until can select for soft error). 802 * 803 * Do not wake up user since there currently is no mechanism for 804 * reporting soft errors (yet - a kqueue filter may be added). 805 */ 806 static void 807 tcp_notify(inp, error) 808 struct inpcb *inp; 809 int error; 810 { 811 struct tcpcb *tp = (struct tcpcb *)inp->inp_ppcb; 812 813 /* 814 * Ignore some errors if we are hooked up. 815 * If connection hasn't completed, has retransmitted several times, 816 * and receives a second error, give up now. This is better 817 * than waiting a long time to establish a connection that 818 * can never complete. 819 */ 820 if (tp->t_state == TCPS_ESTABLISHED && 821 (error == EHOSTUNREACH || error == ENETUNREACH || 822 error == EHOSTDOWN)) { 823 return; 824 } else if (tp->t_state < TCPS_ESTABLISHED && tp->t_rxtshift > 3 && 825 tp->t_softerror) 826 tcp_drop(tp, error); 827 else 828 tp->t_softerror = error; 829 #if 0 830 wakeup((caddr_t) &so->so_timeo); 831 sorwakeup(so); 832 sowwakeup(so); 833 #endif 834 } 835 836 static int 837 tcp_pcblist(SYSCTL_HANDLER_ARGS) 838 { 839 int error, i, n, s; 840 struct inpcb *inp, **inp_list; 841 inp_gen_t gencnt; 842 struct xinpgen xig; 843 844 /* 845 * The process of preparing the TCB list is too time-consuming and 846 * resource-intensive to repeat twice on every request. 847 */ 848 if (req->oldptr == 0) { 849 n = tcbinfo.ipi_count; 850 req->oldidx = 2 * (sizeof xig) 851 + (n + n/8) * sizeof(struct xtcpcb); 852 return 0; 853 } 854 855 if (req->newptr != 0) 856 return EPERM; 857 858 /* 859 * OK, now we're committed to doing something. 860 */ 861 s = splnet(); 862 gencnt = tcbinfo.ipi_gencnt; 863 n = tcbinfo.ipi_count; 864 splx(s); 865 866 xig.xig_len = sizeof xig; 867 xig.xig_count = n; 868 xig.xig_gen = gencnt; 869 xig.xig_sogen = so_gencnt; 870 error = SYSCTL_OUT(req, &xig, sizeof xig); 871 if (error) 872 return error; 873 874 inp_list = malloc(n * sizeof *inp_list, M_TEMP, M_WAITOK); 875 if (inp_list == 0) 876 return ENOMEM; 877 878 s = splnet(); 879 for (inp = LIST_FIRST(tcbinfo.listhead), i = 0; inp && i < n; 880 inp = LIST_NEXT(inp, inp_list)) { 881 if (inp->inp_gencnt <= gencnt && !prison_xinpcb(req->td, inp)) 882 inp_list[i++] = inp; 883 } 884 splx(s); 885 n = i; 886 887 error = 0; 888 for (i = 0; i < n; i++) { 889 inp = inp_list[i]; 890 if (inp->inp_gencnt <= gencnt) { 891 struct xtcpcb xt; 892 caddr_t inp_ppcb; 893 xt.xt_len = sizeof xt; 894 /* XXX should avoid extra copy */ 895 bcopy(inp, &xt.xt_inp, sizeof *inp); 896 inp_ppcb = inp->inp_ppcb; 897 if (inp_ppcb != NULL) 898 bcopy(inp_ppcb, &xt.xt_tp, sizeof xt.xt_tp); 899 else 900 bzero((char *) &xt.xt_tp, sizeof xt.xt_tp); 901 if (inp->inp_socket) 902 sotoxsocket(inp->inp_socket, &xt.xt_socket); 903 error = SYSCTL_OUT(req, &xt, sizeof xt); 904 } 905 } 906 if (!error) { 907 /* 908 * Give the user an updated idea of our state. 909 * If the generation differs from what we told 910 * her before, she knows that something happened 911 * while we were processing this request, and it 912 * might be necessary to retry. 913 */ 914 s = splnet(); 915 xig.xig_gen = tcbinfo.ipi_gencnt; 916 xig.xig_sogen = so_gencnt; 917 xig.xig_count = tcbinfo.ipi_count; 918 splx(s); 919 error = SYSCTL_OUT(req, &xig, sizeof xig); 920 } 921 free(inp_list, M_TEMP); 922 return error; 923 } 924 925 SYSCTL_PROC(_net_inet_tcp, TCPCTL_PCBLIST, pcblist, CTLFLAG_RD, 0, 0, 926 tcp_pcblist, "S,xtcpcb", "List of active TCP connections"); 927 928 static int 929 tcp_getcred(SYSCTL_HANDLER_ARGS) 930 { 931 struct sockaddr_in addrs[2]; 932 struct inpcb *inp; 933 int error, s; 934 935 error = suser(req->td); 936 if (error) 937 return (error); 938 error = SYSCTL_IN(req, addrs, sizeof(addrs)); 939 if (error) 940 return (error); 941 s = splnet(); 942 inp = in_pcblookup_hash(&tcbinfo, addrs[1].sin_addr, addrs[1].sin_port, 943 addrs[0].sin_addr, addrs[0].sin_port, 0, NULL); 944 if (inp == NULL || inp->inp_socket == NULL) { 945 error = ENOENT; 946 goto out; 947 } 948 error = SYSCTL_OUT(req, inp->inp_socket->so_cred, sizeof(struct ucred)); 949 out: 950 splx(s); 951 return (error); 952 } 953 954 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, getcred, CTLTYPE_OPAQUE|CTLFLAG_RW, 955 0, 0, tcp_getcred, "S,ucred", "Get the ucred of a TCP connection"); 956 957 #ifdef INET6 958 static int 959 tcp6_getcred(SYSCTL_HANDLER_ARGS) 960 { 961 struct sockaddr_in6 addrs[2]; 962 struct inpcb *inp; 963 int error, s, mapped = 0; 964 965 error = suser(req->td); 966 if (error) 967 return (error); 968 error = SYSCTL_IN(req, addrs, sizeof(addrs)); 969 if (error) 970 return (error); 971 if (IN6_IS_ADDR_V4MAPPED(&addrs[0].sin6_addr)) { 972 if (IN6_IS_ADDR_V4MAPPED(&addrs[1].sin6_addr)) 973 mapped = 1; 974 else 975 return (EINVAL); 976 } 977 s = splnet(); 978 if (mapped == 1) 979 inp = in_pcblookup_hash(&tcbinfo, 980 *(struct in_addr *)&addrs[1].sin6_addr.s6_addr[12], 981 addrs[1].sin6_port, 982 *(struct in_addr *)&addrs[0].sin6_addr.s6_addr[12], 983 addrs[0].sin6_port, 984 0, NULL); 985 else 986 inp = in6_pcblookup_hash(&tcbinfo, &addrs[1].sin6_addr, 987 addrs[1].sin6_port, 988 &addrs[0].sin6_addr, addrs[0].sin6_port, 989 0, NULL); 990 if (inp == NULL || inp->inp_socket == NULL) { 991 error = ENOENT; 992 goto out; 993 } 994 error = SYSCTL_OUT(req, inp->inp_socket->so_cred, 995 sizeof(struct ucred)); 996 out: 997 splx(s); 998 return (error); 999 } 1000 1001 SYSCTL_PROC(_net_inet6_tcp6, OID_AUTO, getcred, CTLTYPE_OPAQUE|CTLFLAG_RW, 1002 0, 0, 1003 tcp6_getcred, "S,ucred", "Get the ucred of a TCP6 connection"); 1004 #endif 1005 1006 1007 void 1008 tcp_ctlinput(cmd, sa, vip) 1009 int cmd; 1010 struct sockaddr *sa; 1011 void *vip; 1012 { 1013 struct ip *ip = vip; 1014 struct tcphdr *th; 1015 struct in_addr faddr; 1016 struct inpcb *inp; 1017 struct tcpcb *tp; 1018 void (*notify) (struct inpcb *, int) = tcp_notify; 1019 tcp_seq icmp_seq; 1020 int s; 1021 1022 faddr = ((struct sockaddr_in *)sa)->sin_addr; 1023 if (sa->sa_family != AF_INET || faddr.s_addr == INADDR_ANY) 1024 return; 1025 1026 if (cmd == PRC_QUENCH) 1027 notify = tcp_quench; 1028 else if (icmp_may_rst && (cmd == PRC_UNREACH_ADMIN_PROHIB || 1029 cmd == PRC_UNREACH_PORT || cmd == PRC_TIMXCEED_INTRANS) && ip) 1030 notify = tcp_drop_syn_sent; 1031 else if (cmd == PRC_MSGSIZE) 1032 notify = tcp_mtudisc; 1033 else if (PRC_IS_REDIRECT(cmd)) { 1034 ip = 0; 1035 notify = in_rtchange; 1036 } else if (cmd == PRC_HOSTDEAD) 1037 ip = 0; 1038 else if ((unsigned)cmd > PRC_NCMDS || inetctlerrmap[cmd] == 0) 1039 return; 1040 if (ip) { 1041 s = splnet(); 1042 th = (struct tcphdr *)((caddr_t)ip 1043 + (IP_VHL_HL(ip->ip_vhl) << 2)); 1044 inp = in_pcblookup_hash(&tcbinfo, faddr, th->th_dport, 1045 ip->ip_src, th->th_sport, 0, NULL); 1046 if (inp != NULL && inp->inp_socket != NULL) { 1047 icmp_seq = htonl(th->th_seq); 1048 tp = intotcpcb(inp); 1049 if (SEQ_GEQ(icmp_seq, tp->snd_una) && 1050 SEQ_LT(icmp_seq, tp->snd_max)) 1051 (*notify)(inp, inetctlerrmap[cmd]); 1052 } else { 1053 struct in_conninfo inc; 1054 1055 inc.inc_fport = th->th_dport; 1056 inc.inc_lport = th->th_sport; 1057 inc.inc_faddr = faddr; 1058 inc.inc_laddr = ip->ip_src; 1059 #ifdef INET6 1060 inc.inc_isipv6 = 0; 1061 #endif 1062 syncache_unreach(&inc, th); 1063 } 1064 splx(s); 1065 } else 1066 in_pcbnotifyall(&tcb, faddr, inetctlerrmap[cmd], notify); 1067 } 1068 1069 #ifdef INET6 1070 void 1071 tcp6_ctlinput(cmd, sa, d) 1072 int cmd; 1073 struct sockaddr *sa; 1074 void *d; 1075 { 1076 struct tcphdr th; 1077 void (*notify) (struct inpcb *, int) = tcp_notify; 1078 struct ip6_hdr *ip6; 1079 struct mbuf *m; 1080 struct ip6ctlparam *ip6cp = NULL; 1081 const struct sockaddr_in6 *sa6_src = NULL; 1082 int off; 1083 struct tcp_portonly { 1084 u_int16_t th_sport; 1085 u_int16_t th_dport; 1086 } *thp; 1087 1088 if (sa->sa_family != AF_INET6 || 1089 sa->sa_len != sizeof(struct sockaddr_in6)) 1090 return; 1091 1092 if (cmd == PRC_QUENCH) 1093 notify = tcp_quench; 1094 else if (cmd == PRC_MSGSIZE) 1095 notify = tcp_mtudisc; 1096 else if (!PRC_IS_REDIRECT(cmd) && 1097 ((unsigned)cmd > PRC_NCMDS || inet6ctlerrmap[cmd] == 0)) 1098 return; 1099 1100 /* if the parameter is from icmp6, decode it. */ 1101 if (d != NULL) { 1102 ip6cp = (struct ip6ctlparam *)d; 1103 m = ip6cp->ip6c_m; 1104 ip6 = ip6cp->ip6c_ip6; 1105 off = ip6cp->ip6c_off; 1106 sa6_src = ip6cp->ip6c_src; 1107 } else { 1108 m = NULL; 1109 ip6 = NULL; 1110 off = 0; /* fool gcc */ 1111 sa6_src = &sa6_any; 1112 } 1113 1114 if (ip6) { 1115 struct in_conninfo inc; 1116 /* 1117 * XXX: We assume that when IPV6 is non NULL, 1118 * M and OFF are valid. 1119 */ 1120 1121 /* check if we can safely examine src and dst ports */ 1122 if (m->m_pkthdr.len < off + sizeof(*thp)) 1123 return; 1124 1125 bzero(&th, sizeof(th)); 1126 m_copydata(m, off, sizeof(*thp), (caddr_t)&th); 1127 1128 in6_pcbnotify(&tcb, sa, th.th_dport, 1129 (struct sockaddr *)ip6cp->ip6c_src, 1130 th.th_sport, cmd, notify); 1131 1132 inc.inc_fport = th.th_dport; 1133 inc.inc_lport = th.th_sport; 1134 inc.inc6_faddr = ((struct sockaddr_in6 *)sa)->sin6_addr; 1135 inc.inc6_laddr = ip6cp->ip6c_src->sin6_addr; 1136 inc.inc_isipv6 = 1; 1137 syncache_unreach(&inc, &th); 1138 } else 1139 in6_pcbnotify(&tcb, sa, 0, (const struct sockaddr *)sa6_src, 1140 0, cmd, notify); 1141 } 1142 #endif /* INET6 */ 1143 1144 1145 /* 1146 * Following is where TCP initial sequence number generation occurs. 1147 * 1148 * There are two places where we must use initial sequence numbers: 1149 * 1. In SYN-ACK packets. 1150 * 2. In SYN packets. 1151 * 1152 * All ISNs for SYN-ACK packets are generated by the syncache. See 1153 * tcp_syncache.c for details. 1154 * 1155 * The ISNs in SYN packets must be monotonic; TIME_WAIT recycling 1156 * depends on this property. In addition, these ISNs should be 1157 * unguessable so as to prevent connection hijacking. To satisfy 1158 * the requirements of this situation, the algorithm outlined in 1159 * RFC 1948 is used to generate sequence numbers. 1160 * 1161 * Implementation details: 1162 * 1163 * Time is based off the system timer, and is corrected so that it 1164 * increases by one megabyte per second. This allows for proper 1165 * recycling on high speed LANs while still leaving over an hour 1166 * before rollover. 1167 * 1168 * net.inet.tcp.isn_reseed_interval controls the number of seconds 1169 * between seeding of isn_secret. This is normally set to zero, 1170 * as reseeding should not be necessary. 1171 * 1172 */ 1173 1174 #define ISN_BYTES_PER_SECOND 1048576 1175 1176 u_char isn_secret[32]; 1177 int isn_last_reseed; 1178 MD5_CTX isn_ctx; 1179 1180 tcp_seq 1181 tcp_new_isn(tp) 1182 struct tcpcb *tp; 1183 { 1184 u_int32_t md5_buffer[4]; 1185 tcp_seq new_isn; 1186 1187 /* Seed if this is the first use, reseed if requested. */ 1188 if ((isn_last_reseed == 0) || ((tcp_isn_reseed_interval > 0) && 1189 (((u_int)isn_last_reseed + (u_int)tcp_isn_reseed_interval*hz) 1190 < (u_int)ticks))) { 1191 read_random_unlimited(&isn_secret, sizeof(isn_secret)); 1192 isn_last_reseed = ticks; 1193 } 1194 1195 /* Compute the md5 hash and return the ISN. */ 1196 MD5Init(&isn_ctx); 1197 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_fport, sizeof(u_short)); 1198 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_lport, sizeof(u_short)); 1199 #ifdef INET6 1200 if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0) { 1201 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_faddr, 1202 sizeof(struct in6_addr)); 1203 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_laddr, 1204 sizeof(struct in6_addr)); 1205 } else 1206 #endif 1207 { 1208 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_faddr, 1209 sizeof(struct in_addr)); 1210 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_laddr, 1211 sizeof(struct in_addr)); 1212 } 1213 MD5Update(&isn_ctx, (u_char *) &isn_secret, sizeof(isn_secret)); 1214 MD5Final((u_char *) &md5_buffer, &isn_ctx); 1215 new_isn = (tcp_seq) md5_buffer[0]; 1216 new_isn += ticks * (ISN_BYTES_PER_SECOND / hz); 1217 return new_isn; 1218 } 1219 1220 /* 1221 * When a source quench is received, close congestion window 1222 * to one segment. We will gradually open it again as we proceed. 1223 */ 1224 void 1225 tcp_quench(inp, errno) 1226 struct inpcb *inp; 1227 int errno; 1228 { 1229 struct tcpcb *tp = intotcpcb(inp); 1230 1231 if (tp) 1232 tp->snd_cwnd = tp->t_maxseg; 1233 } 1234 1235 /* 1236 * When a specific ICMP unreachable message is received and the 1237 * connection state is SYN-SENT, drop the connection. This behavior 1238 * is controlled by the icmp_may_rst sysctl. 1239 */ 1240 void 1241 tcp_drop_syn_sent(inp, errno) 1242 struct inpcb *inp; 1243 int errno; 1244 { 1245 struct tcpcb *tp = intotcpcb(inp); 1246 1247 if (tp && tp->t_state == TCPS_SYN_SENT) 1248 tcp_drop(tp, errno); 1249 } 1250 1251 /* 1252 * When `need fragmentation' ICMP is received, update our idea of the MSS 1253 * based on the new value in the route. Also nudge TCP to send something, 1254 * since we know the packet we just sent was dropped. 1255 * This duplicates some code in the tcp_mss() function in tcp_input.c. 1256 */ 1257 void 1258 tcp_mtudisc(inp, errno) 1259 struct inpcb *inp; 1260 int errno; 1261 { 1262 struct tcpcb *tp = intotcpcb(inp); 1263 struct rtentry *rt; 1264 struct rmxp_tao *taop; 1265 struct socket *so = inp->inp_socket; 1266 int offered; 1267 int mss; 1268 #ifdef INET6 1269 int isipv6 = (tp->t_inpcb->inp_vflag & INP_IPV6) != 0; 1270 #endif /* INET6 */ 1271 1272 if (tp) { 1273 #ifdef INET6 1274 if (isipv6) 1275 rt = tcp_rtlookup6(&inp->inp_inc); 1276 else 1277 #endif /* INET6 */ 1278 rt = tcp_rtlookup(&inp->inp_inc); 1279 if (!rt || !rt->rt_rmx.rmx_mtu) { 1280 tp->t_maxopd = tp->t_maxseg = 1281 #ifdef INET6 1282 isipv6 ? tcp_v6mssdflt : 1283 #endif /* INET6 */ 1284 tcp_mssdflt; 1285 return; 1286 } 1287 taop = rmx_taop(rt->rt_rmx); 1288 offered = taop->tao_mssopt; 1289 mss = rt->rt_rmx.rmx_mtu - 1290 #ifdef INET6 1291 (isipv6 ? 1292 sizeof(struct ip6_hdr) + sizeof(struct tcphdr) : 1293 #endif /* INET6 */ 1294 sizeof(struct tcpiphdr) 1295 #ifdef INET6 1296 ) 1297 #endif /* INET6 */ 1298 ; 1299 1300 if (offered) 1301 mss = min(mss, offered); 1302 /* 1303 * XXX - The above conditional probably violates the TCP 1304 * spec. The problem is that, since we don't know the 1305 * other end's MSS, we are supposed to use a conservative 1306 * default. But, if we do that, then MTU discovery will 1307 * never actually take place, because the conservative 1308 * default is much less than the MTUs typically seen 1309 * on the Internet today. For the moment, we'll sweep 1310 * this under the carpet. 1311 * 1312 * The conservative default might not actually be a problem 1313 * if the only case this occurs is when sending an initial 1314 * SYN with options and data to a host we've never talked 1315 * to before. Then, they will reply with an MSS value which 1316 * will get recorded and the new parameters should get 1317 * recomputed. For Further Study. 1318 */ 1319 if (tp->t_maxopd <= mss) 1320 return; 1321 tp->t_maxopd = mss; 1322 1323 if ((tp->t_flags & (TF_REQ_TSTMP|TF_NOOPT)) == TF_REQ_TSTMP && 1324 (tp->t_flags & TF_RCVD_TSTMP) == TF_RCVD_TSTMP) 1325 mss -= TCPOLEN_TSTAMP_APPA; 1326 if ((tp->t_flags & (TF_REQ_CC|TF_NOOPT)) == TF_REQ_CC && 1327 (tp->t_flags & TF_RCVD_CC) == TF_RCVD_CC) 1328 mss -= TCPOLEN_CC_APPA; 1329 #if (MCLBYTES & (MCLBYTES - 1)) == 0 1330 if (mss > MCLBYTES) 1331 mss &= ~(MCLBYTES-1); 1332 #else 1333 if (mss > MCLBYTES) 1334 mss = mss / MCLBYTES * MCLBYTES; 1335 #endif 1336 if (so->so_snd.sb_hiwat < mss) 1337 mss = so->so_snd.sb_hiwat; 1338 1339 tp->t_maxseg = mss; 1340 1341 tcpstat.tcps_mturesent++; 1342 tp->t_rtttime = 0; 1343 tp->snd_nxt = tp->snd_una; 1344 tcp_output(tp); 1345 } 1346 } 1347 1348 /* 1349 * Look-up the routing entry to the peer of this inpcb. If no route 1350 * is found and it cannot be allocated the return NULL. This routine 1351 * is called by TCP routines that access the rmx structure and by tcp_mss 1352 * to get the interface MTU. 1353 */ 1354 struct rtentry * 1355 tcp_rtlookup(inc) 1356 struct in_conninfo *inc; 1357 { 1358 struct route *ro; 1359 struct rtentry *rt; 1360 1361 ro = &inc->inc_route; 1362 rt = ro->ro_rt; 1363 if (rt == NULL || !(rt->rt_flags & RTF_UP)) { 1364 /* No route yet, so try to acquire one */ 1365 if (inc->inc_faddr.s_addr != INADDR_ANY) { 1366 ro->ro_dst.sa_family = AF_INET; 1367 ro->ro_dst.sa_len = sizeof(struct sockaddr_in); 1368 ((struct sockaddr_in *) &ro->ro_dst)->sin_addr = 1369 inc->inc_faddr; 1370 rtalloc(ro); 1371 rt = ro->ro_rt; 1372 } 1373 } 1374 return rt; 1375 } 1376 1377 #ifdef INET6 1378 struct rtentry * 1379 tcp_rtlookup6(inc) 1380 struct in_conninfo *inc; 1381 { 1382 struct route_in6 *ro6; 1383 struct rtentry *rt; 1384 1385 ro6 = &inc->inc6_route; 1386 rt = ro6->ro_rt; 1387 if (rt == NULL || !(rt->rt_flags & RTF_UP)) { 1388 /* No route yet, so try to acquire one */ 1389 if (!IN6_IS_ADDR_UNSPECIFIED(&inc->inc6_faddr)) { 1390 ro6->ro_dst.sin6_family = AF_INET6; 1391 ro6->ro_dst.sin6_len = sizeof(struct sockaddr_in6); 1392 ro6->ro_dst.sin6_addr = inc->inc6_faddr; 1393 rtalloc((struct route *)ro6); 1394 rt = ro6->ro_rt; 1395 } 1396 } 1397 return rt; 1398 } 1399 #endif /* INET6 */ 1400 1401 #ifdef IPSEC 1402 /* compute ESP/AH header size for TCP, including outer IP header. */ 1403 size_t 1404 ipsec_hdrsiz_tcp(tp) 1405 struct tcpcb *tp; 1406 { 1407 struct inpcb *inp; 1408 struct mbuf *m; 1409 size_t hdrsiz; 1410 struct ip *ip; 1411 #ifdef INET6 1412 struct ip6_hdr *ip6; 1413 #endif /* INET6 */ 1414 struct tcphdr *th; 1415 1416 if ((tp == NULL) || ((inp = tp->t_inpcb) == NULL)) 1417 return 0; 1418 MGETHDR(m, M_DONTWAIT, MT_DATA); 1419 if (!m) 1420 return 0; 1421 1422 #ifdef INET6 1423 if ((inp->inp_vflag & INP_IPV6) != 0) { 1424 ip6 = mtod(m, struct ip6_hdr *); 1425 th = (struct tcphdr *)(ip6 + 1); 1426 m->m_pkthdr.len = m->m_len = 1427 sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 1428 tcp_fillheaders(tp, ip6, th); 1429 hdrsiz = ipsec6_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp); 1430 } else 1431 #endif /* INET6 */ 1432 { 1433 ip = mtod(m, struct ip *); 1434 th = (struct tcphdr *)(ip + 1); 1435 m->m_pkthdr.len = m->m_len = sizeof(struct tcpiphdr); 1436 tcp_fillheaders(tp, ip, th); 1437 hdrsiz = ipsec4_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp); 1438 } 1439 1440 m_free(m); 1441 return hdrsiz; 1442 } 1443 #endif /*IPSEC*/ 1444 1445 /* 1446 * Return a pointer to the cached information about the remote host. 1447 * The cached information is stored in the protocol specific part of 1448 * the route metrics. 1449 */ 1450 struct rmxp_tao * 1451 tcp_gettaocache(inc) 1452 struct in_conninfo *inc; 1453 { 1454 struct rtentry *rt; 1455 1456 #ifdef INET6 1457 if (inc->inc_isipv6) 1458 rt = tcp_rtlookup6(inc); 1459 else 1460 #endif /* INET6 */ 1461 rt = tcp_rtlookup(inc); 1462 1463 /* Make sure this is a host route and is up. */ 1464 if (rt == NULL || 1465 (rt->rt_flags & (RTF_UP|RTF_HOST)) != (RTF_UP|RTF_HOST)) 1466 return NULL; 1467 1468 return rmx_taop(rt->rt_rmx); 1469 } 1470 1471 /* 1472 * Clear all the TAO cache entries, called from tcp_init. 1473 * 1474 * XXX 1475 * This routine is just an empty one, because we assume that the routing 1476 * routing tables are initialized at the same time when TCP, so there is 1477 * nothing in the cache left over. 1478 */ 1479 static void 1480 tcp_cleartaocache() 1481 { 1482 } 1483 1484 /* 1485 * TCP BANDWIDTH DELAY PRODUCT WINDOW LIMITING 1486 * 1487 * This code attempts to calculate the bandwidth-delay product as a 1488 * means of determining the optimal window size to maximize bandwidth, 1489 * minimize RTT, and avoid the over-allocation of buffers on interfaces and 1490 * routers. This code also does a fairly good job keeping RTTs in check 1491 * across slow links like modems. We implement an algorithm which is very 1492 * similar (but not meant to be) TCP/Vegas. The code operates on the 1493 * transmitter side of a TCP connection and so only effects the transmit 1494 * side of the connection. 1495 * 1496 * BACKGROUND: TCP makes no provision for the management of buffer space 1497 * at the end points or at the intermediate routers and switches. A TCP 1498 * stream, whether using NewReno or not, will eventually buffer as 1499 * many packets as it is able and the only reason this typically works is 1500 * due to the fairly small default buffers made available for a connection 1501 * (typicaly 16K or 32K). As machines use larger windows and/or window 1502 * scaling it is now fairly easy for even a single TCP connection to blow-out 1503 * all available buffer space not only on the local interface, but on 1504 * intermediate routers and switches as well. NewReno makes a misguided 1505 * attempt to 'solve' this problem by waiting for an actual failure to occur, 1506 * then backing off, then steadily increasing the window again until another 1507 * failure occurs, ad-infinitum. This results in terrible oscillation that 1508 * is only made worse as network loads increase and the idea of intentionally 1509 * blowing out network buffers is, frankly, a terrible way to manage network 1510 * resources. 1511 * 1512 * It is far better to limit the transmit window prior to the failure 1513 * condition being achieved. There are two general ways to do this: First 1514 * you can 'scan' through different transmit window sizes and locate the 1515 * point where the RTT stops increasing, indicating that you have filled the 1516 * pipe, then scan backwards until you note that RTT stops decreasing, then 1517 * repeat ad-infinitum. This method works in principle but has severe 1518 * implementation issues due to RTT variances, timer granularity, and 1519 * instability in the algorithm which can lead to many false positives and 1520 * create oscillations as well as interact badly with other TCP streams 1521 * implementing the same algorithm. 1522 * 1523 * The second method is to limit the window to the bandwidth delay product 1524 * of the link. This is the method we implement. RTT variances and our 1525 * own manipulation of the congestion window, bwnd, can potentially 1526 * destabilize the algorithm. For this reason we have to stabilize the 1527 * elements used to calculate the window. We do this by using the minimum 1528 * observed RTT, the long term average of the observed bandwidth, and 1529 * by adding two segments worth of slop. It isn't perfect but it is able 1530 * to react to changing conditions and gives us a very stable basis on 1531 * which to extend the algorithm. 1532 */ 1533 void 1534 tcp_xmit_bandwidth_limit(struct tcpcb *tp, tcp_seq ack_seq) 1535 { 1536 u_long bw; 1537 u_long bwnd; 1538 int save_ticks; 1539 1540 /* 1541 * If inflight_enable is disabled in the middle of a tcp connection, 1542 * make sure snd_bwnd is effectively disabled. 1543 */ 1544 if (tcp_inflight_enable == 0) { 1545 tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 1546 tp->snd_bandwidth = 0; 1547 return; 1548 } 1549 1550 /* 1551 * Figure out the bandwidth. Due to the tick granularity this 1552 * is a very rough number and it MUST be averaged over a fairly 1553 * long period of time. XXX we need to take into account a link 1554 * that is not using all available bandwidth, but for now our 1555 * slop will ramp us up if this case occurs and the bandwidth later 1556 * increases. 1557 * 1558 * Note: if ticks rollover 'bw' may wind up negative. We must 1559 * effectively reset t_bw_rtttime for this case. 1560 */ 1561 save_ticks = ticks; 1562 if ((u_int)(save_ticks - tp->t_bw_rtttime) < 1) 1563 return; 1564 1565 bw = (int64_t)(ack_seq - tp->t_bw_rtseq) * hz / 1566 (save_ticks - tp->t_bw_rtttime); 1567 tp->t_bw_rtttime = save_ticks; 1568 tp->t_bw_rtseq = ack_seq; 1569 if (tp->t_bw_rtttime == 0 || (int)bw < 0) 1570 return; 1571 bw = ((int64_t)tp->snd_bandwidth * 15 + bw) >> 4; 1572 1573 tp->snd_bandwidth = bw; 1574 1575 /* 1576 * Calculate the semi-static bandwidth delay product, plus two maximal 1577 * segments. The additional slop puts us squarely in the sweet 1578 * spot and also handles the bandwidth run-up case. Without the 1579 * slop we could be locking ourselves into a lower bandwidth. 1580 * 1581 * Situations Handled: 1582 * (1) Prevents over-queueing of packets on LANs, especially on 1583 * high speed LANs, allowing larger TCP buffers to be 1584 * specified, and also does a good job preventing 1585 * over-queueing of packets over choke points like modems 1586 * (at least for the transmit side). 1587 * 1588 * (2) Is able to handle changing network loads (bandwidth 1589 * drops so bwnd drops, bandwidth increases so bwnd 1590 * increases). 1591 * 1592 * (3) Theoretically should stabilize in the face of multiple 1593 * connections implementing the same algorithm (this may need 1594 * a little work). 1595 * 1596 * (4) Stability value (defaults to 20 = 2 maximal packets) can 1597 * be adjusted with a sysctl but typically only needs to be on 1598 * very slow connections. A value no smaller then 5 should 1599 * be used, but only reduce this default if you have no other 1600 * choice. 1601 */ 1602 #define USERTT ((tp->t_srtt + tp->t_rttbest) / 2) 1603 bwnd = (int64_t)bw * USERTT / (hz << TCP_RTT_SHIFT) + tcp_inflight_stab * (int)tp->t_maxseg / 10; 1604 #undef USERTT 1605 1606 if (tcp_inflight_debug > 0) { 1607 static int ltime; 1608 if ((u_int)(ticks - ltime) >= hz / tcp_inflight_debug) { 1609 ltime = ticks; 1610 printf("%p bw %ld rttbest %d srtt %d bwnd %ld\n", 1611 tp, 1612 bw, 1613 tp->t_rttbest, 1614 tp->t_srtt, 1615 bwnd 1616 ); 1617 } 1618 } 1619 if ((long)bwnd < tcp_inflight_min) 1620 bwnd = tcp_inflight_min; 1621 if (bwnd > tcp_inflight_max) 1622 bwnd = tcp_inflight_max; 1623 if ((long)bwnd < tp->t_maxseg * 2) 1624 bwnd = tp->t_maxseg * 2; 1625 tp->snd_bwnd = bwnd; 1626 } 1627