1 /* 2 * Copyright (c) 1982, 1986, 1988 Regents of the University of California. 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms are permitted 6 * provided that the above copyright notice and this paragraph are 7 * duplicated in all such forms and that any documentation, 8 * advertising materials, and other materials related to such 9 * distribution and use acknowledge that the software was developed 10 * by the University of California, Berkeley. The name of the 11 * University may not be used to endorse or promote products derived 12 * from this software without specific prior written permission. 13 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR 14 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED 15 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE. 16 * 17 * @(#)tcp_input.c 7.15.1.3 (Berkeley) 02/15/89 18 */ 19 20 #include "param.h" 21 #include "systm.h" 22 #include "mbuf.h" 23 #include "protosw.h" 24 #include "socket.h" 25 #include "socketvar.h" 26 #include "errno.h" 27 28 #include "../net/if.h" 29 #include "../net/route.h" 30 31 #include "in.h" 32 #include "in_pcb.h" 33 #include "in_systm.h" 34 #include "ip.h" 35 #include "ip_var.h" 36 #include "tcp.h" 37 #include "tcp_fsm.h" 38 #include "tcp_seq.h" 39 #include "tcp_timer.h" 40 #include "tcp_var.h" 41 #include "tcpip.h" 42 #include "tcp_debug.h" 43 44 int tcpprintfs = 0; 45 int tcpcksum = 1; 46 int tcprexmtthresh = 3; 47 struct tcpiphdr tcp_saveti; 48 49 struct tcpcb *tcp_newtcpcb(); 50 51 /* 52 * Insert segment ti into reassembly queue of tcp with 53 * control block tp. Return TH_FIN if reassembly now includes 54 * a segment with FIN. The macro form does the common case inline 55 * (segment is the next to be received on an established connection, 56 * and the queue is empty), avoiding linkage into and removal 57 * from the queue and repetition of various conversions. 58 * Set DELACK for segments received in order, but ack immediately 59 * when segments are out of order (so fast retransmit can work). 60 */ 61 #define TCP_REASS(tp, ti, m, so, flags) { \ 62 if ((ti)->ti_seq == (tp)->rcv_nxt && \ 63 (tp)->seg_next == (struct tcpiphdr *)(tp) && \ 64 (tp)->t_state == TCPS_ESTABLISHED) { \ 65 tp->t_flags |= TF_DELACK; \ 66 (tp)->rcv_nxt += (ti)->ti_len; \ 67 flags = (ti)->ti_flags & TH_FIN; \ 68 tcpstat.tcps_rcvpack++;\ 69 tcpstat.tcps_rcvbyte += (ti)->ti_len;\ 70 sbappend(&(so)->so_rcv, (m)); \ 71 sorwakeup(so); \ 72 } else { \ 73 (flags) = tcp_reass((tp), (ti)); \ 74 tp->t_flags |= TF_ACKNOW; \ 75 } \ 76 } 77 78 tcp_reass(tp, ti) 79 register struct tcpcb *tp; 80 register struct tcpiphdr *ti; 81 { 82 register struct tcpiphdr *q; 83 struct socket *so = tp->t_inpcb->inp_socket; 84 struct mbuf *m; 85 int flags; 86 87 /* 88 * Call with ti==0 after become established to 89 * force pre-ESTABLISHED data up to user socket. 90 */ 91 if (ti == 0) 92 goto present; 93 94 /* 95 * Find a segment which begins after this one does. 96 */ 97 for (q = tp->seg_next; q != (struct tcpiphdr *)tp; 98 q = (struct tcpiphdr *)q->ti_next) 99 if (SEQ_GT(q->ti_seq, ti->ti_seq)) 100 break; 101 102 /* 103 * If there is a preceding segment, it may provide some of 104 * our data already. If so, drop the data from the incoming 105 * segment. If it provides all of our data, drop us. 106 */ 107 if ((struct tcpiphdr *)q->ti_prev != (struct tcpiphdr *)tp) { 108 register int i; 109 q = (struct tcpiphdr *)q->ti_prev; 110 /* conversion to int (in i) handles seq wraparound */ 111 i = q->ti_seq + q->ti_len - ti->ti_seq; 112 if (i > 0) { 113 if (i >= ti->ti_len) { 114 tcpstat.tcps_rcvduppack++; 115 tcpstat.tcps_rcvdupbyte += ti->ti_len; 116 goto drop; 117 } 118 m_adj(dtom(ti), i); 119 ti->ti_len -= i; 120 ti->ti_seq += i; 121 } 122 q = (struct tcpiphdr *)(q->ti_next); 123 } 124 tcpstat.tcps_rcvoopack++; 125 tcpstat.tcps_rcvoobyte += ti->ti_len; 126 127 /* 128 * While we overlap succeeding segments trim them or, 129 * if they are completely covered, dequeue them. 130 */ 131 while (q != (struct tcpiphdr *)tp) { 132 register int i = (ti->ti_seq + ti->ti_len) - q->ti_seq; 133 if (i <= 0) 134 break; 135 if (i < q->ti_len) { 136 q->ti_seq += i; 137 q->ti_len -= i; 138 m_adj(dtom(q), i); 139 break; 140 } 141 q = (struct tcpiphdr *)q->ti_next; 142 m = dtom(q->ti_prev); 143 remque(q->ti_prev); 144 m_freem(m); 145 } 146 147 /* 148 * Stick new segment in its place. 149 */ 150 insque(ti, q->ti_prev); 151 152 present: 153 /* 154 * Present data to user, advancing rcv_nxt through 155 * completed sequence space. 156 */ 157 if (TCPS_HAVERCVDSYN(tp->t_state) == 0) 158 return (0); 159 ti = tp->seg_next; 160 if (ti == (struct tcpiphdr *)tp || ti->ti_seq != tp->rcv_nxt) 161 return (0); 162 if (tp->t_state == TCPS_SYN_RECEIVED && ti->ti_len) 163 return (0); 164 do { 165 tp->rcv_nxt += ti->ti_len; 166 flags = ti->ti_flags & TH_FIN; 167 remque(ti); 168 m = dtom(ti); 169 ti = (struct tcpiphdr *)ti->ti_next; 170 if (so->so_state & SS_CANTRCVMORE) 171 m_freem(m); 172 else 173 sbappend(&so->so_rcv, m); 174 } while (ti != (struct tcpiphdr *)tp && ti->ti_seq == tp->rcv_nxt); 175 sorwakeup(so); 176 return (flags); 177 drop: 178 m_freem(dtom(ti)); 179 return (0); 180 } 181 182 /* 183 * TCP input routine, follows pages 65-76 of the 184 * protocol specification dated September, 1981 very closely. 185 */ 186 tcp_input(m0) 187 struct mbuf *m0; 188 { 189 register struct tcpiphdr *ti; 190 struct inpcb *inp; 191 register struct mbuf *m; 192 struct mbuf *om = 0; 193 int len, tlen, off; 194 register struct tcpcb *tp = 0; 195 register int tiflags; 196 struct socket *so; 197 int todrop, acked, ourfinisacked, needoutput = 0; 198 short ostate; 199 struct in_addr laddr; 200 int dropsocket = 0; 201 int iss = 0; 202 203 tcpstat.tcps_rcvtotal++; 204 /* 205 * Get IP and TCP header together in first mbuf. 206 * Note: IP leaves IP header in first mbuf. 207 */ 208 m = m0; 209 ti = mtod(m, struct tcpiphdr *); 210 if (((struct ip *)ti)->ip_hl > (sizeof (struct ip) >> 2)) 211 ip_stripoptions((struct ip *)ti, (struct mbuf *)0); 212 if (m->m_off > MMAXOFF || m->m_len < sizeof (struct tcpiphdr)) { 213 if ((m = m_pullup(m, sizeof (struct tcpiphdr))) == 0) { 214 tcpstat.tcps_rcvshort++; 215 return; 216 } 217 ti = mtod(m, struct tcpiphdr *); 218 } 219 220 /* 221 * Checksum extended TCP header and data. 222 */ 223 tlen = ((struct ip *)ti)->ip_len; 224 len = sizeof (struct ip) + tlen; 225 if (tcpcksum) { 226 ti->ti_next = ti->ti_prev = 0; 227 ti->ti_x1 = 0; 228 ti->ti_len = (u_short)tlen; 229 ti->ti_len = htons((u_short)ti->ti_len); 230 if (ti->ti_sum = in_cksum(m, len)) { 231 if (tcpprintfs) 232 printf("tcp sum: src %x\n", ti->ti_src); 233 tcpstat.tcps_rcvbadsum++; 234 goto drop; 235 } 236 } 237 238 /* 239 * Check that TCP offset makes sense, 240 * pull out TCP options and adjust length. 241 */ 242 off = ti->ti_off << 2; 243 if (off < sizeof (struct tcphdr) || off > tlen) { 244 if (tcpprintfs) 245 printf("tcp off: src %x off %d\n", ti->ti_src, off); 246 tcpstat.tcps_rcvbadoff++; 247 goto drop; 248 } 249 tlen -= off; 250 ti->ti_len = tlen; 251 if (off > sizeof (struct tcphdr)) { 252 if (m->m_len < sizeof(struct ip) + off) { 253 if ((m = m_pullup(m, sizeof (struct ip) + off)) == 0) { 254 tcpstat.tcps_rcvshort++; 255 return; 256 } 257 ti = mtod(m, struct tcpiphdr *); 258 } 259 om = m_get(M_DONTWAIT, MT_DATA); 260 if (om == 0) 261 goto drop; 262 om->m_len = off - sizeof (struct tcphdr); 263 { caddr_t op = mtod(m, caddr_t) + sizeof (struct tcpiphdr); 264 bcopy(op, mtod(om, caddr_t), (unsigned)om->m_len); 265 m->m_len -= om->m_len; 266 bcopy(op+om->m_len, op, 267 (unsigned)(m->m_len-sizeof (struct tcpiphdr))); 268 } 269 } 270 tiflags = ti->ti_flags; 271 272 /* 273 * Drop TCP and IP headers; TCP options were dropped above. 274 */ 275 m->m_off += sizeof(struct tcpiphdr); 276 m->m_len -= sizeof(struct tcpiphdr); 277 278 /* 279 * Convert TCP protocol specific fields to host format. 280 */ 281 ti->ti_seq = ntohl(ti->ti_seq); 282 ti->ti_ack = ntohl(ti->ti_ack); 283 ti->ti_win = ntohs(ti->ti_win); 284 ti->ti_urp = ntohs(ti->ti_urp); 285 286 /* 287 * Locate pcb for segment. 288 */ 289 findpcb: 290 inp = in_pcblookup 291 (&tcb, ti->ti_src, ti->ti_sport, ti->ti_dst, ti->ti_dport, 292 INPLOOKUP_WILDCARD); 293 294 /* 295 * If the state is CLOSED (i.e., TCB does not exist) then 296 * all data in the incoming segment is discarded. 297 * If the TCB exists but is in CLOSED state, it is embryonic, 298 * but should either do a listen or a connect soon. 299 */ 300 if (inp == 0) 301 goto dropwithreset; 302 tp = intotcpcb(inp); 303 if (tp == 0) 304 goto dropwithreset; 305 if (tp->t_state == TCPS_CLOSED) 306 goto drop; 307 so = inp->inp_socket; 308 if (so->so_options & SO_DEBUG) { 309 ostate = tp->t_state; 310 tcp_saveti = *ti; 311 } 312 if (so->so_options & SO_ACCEPTCONN) { 313 so = sonewconn(so); 314 if (so == 0) 315 goto drop; 316 /* 317 * This is ugly, but .... 318 * 319 * Mark socket as temporary until we're 320 * committed to keeping it. The code at 321 * ``drop'' and ``dropwithreset'' check the 322 * flag dropsocket to see if the temporary 323 * socket created here should be discarded. 324 * We mark the socket as discardable until 325 * we're committed to it below in TCPS_LISTEN. 326 */ 327 dropsocket++; 328 inp = (struct inpcb *)so->so_pcb; 329 inp->inp_laddr = ti->ti_dst; 330 inp->inp_lport = ti->ti_dport; 331 #if BSD>=43 332 inp->inp_options = ip_srcroute(); 333 #endif 334 tp = intotcpcb(inp); 335 tp->t_state = TCPS_LISTEN; 336 } 337 338 /* 339 * Segment received on connection. 340 * Reset idle time and keep-alive timer. 341 */ 342 tp->t_idle = 0; 343 tp->t_timer[TCPT_KEEP] = tcp_keepidle; 344 345 /* 346 * Process options if not in LISTEN state, 347 * else do it below (after getting remote address). 348 */ 349 if (om && tp->t_state != TCPS_LISTEN) { 350 tcp_dooptions(tp, om, ti); 351 om = 0; 352 } 353 354 /* 355 * Calculate amount of space in receive window, 356 * and then do TCP input processing. 357 * Receive window is amount of space in rcv queue, 358 * but not less than advertised window. 359 */ 360 { int win; 361 362 win = sbspace(&so->so_rcv); 363 if (win < 0) 364 win = 0; 365 tp->rcv_wnd = MAX(win, (int)(tp->rcv_adv - tp->rcv_nxt)); 366 } 367 368 switch (tp->t_state) { 369 370 /* 371 * If the state is LISTEN then ignore segment if it contains an RST. 372 * If the segment contains an ACK then it is bad and send a RST. 373 * If it does not contain a SYN then it is not interesting; drop it. 374 * Don't bother responding if the destination was a broadcast. 375 * Otherwise initialize tp->rcv_nxt, and tp->irs, select an initial 376 * tp->iss, and send a segment: 377 * <SEQ=ISS><ACK=RCV_NXT><CTL=SYN,ACK> 378 * Also initialize tp->snd_nxt to tp->iss+1 and tp->snd_una to tp->iss. 379 * Fill in remote peer address fields if not previously specified. 380 * Enter SYN_RECEIVED state, and process any other fields of this 381 * segment in this state. 382 */ 383 case TCPS_LISTEN: { 384 struct mbuf *am; 385 register struct sockaddr_in *sin; 386 387 if (tiflags & TH_RST) 388 goto drop; 389 if (tiflags & TH_ACK) 390 goto dropwithreset; 391 if ((tiflags & TH_SYN) == 0) 392 goto drop; 393 if (in_broadcast(ti->ti_dst)) 394 goto drop; 395 am = m_get(M_DONTWAIT, MT_SONAME); 396 if (am == NULL) 397 goto drop; 398 am->m_len = sizeof (struct sockaddr_in); 399 sin = mtod(am, struct sockaddr_in *); 400 sin->sin_family = AF_INET; 401 sin->sin_addr = ti->ti_src; 402 sin->sin_port = ti->ti_sport; 403 laddr = inp->inp_laddr; 404 if (inp->inp_laddr.s_addr == INADDR_ANY) 405 inp->inp_laddr = ti->ti_dst; 406 if (in_pcbconnect(inp, am)) { 407 inp->inp_laddr = laddr; 408 (void) m_free(am); 409 goto drop; 410 } 411 (void) m_free(am); 412 tp->t_template = tcp_template(tp); 413 if (tp->t_template == 0) { 414 tp = tcp_drop(tp, ENOBUFS); 415 dropsocket = 0; /* socket is already gone */ 416 goto drop; 417 } 418 if (om) { 419 tcp_dooptions(tp, om, ti); 420 om = 0; 421 } 422 if (iss) 423 tp->iss = iss; 424 else 425 tp->iss = tcp_iss; 426 tcp_iss += TCP_ISSINCR/2; 427 tp->irs = ti->ti_seq; 428 tcp_sendseqinit(tp); 429 tcp_rcvseqinit(tp); 430 tp->t_flags |= TF_ACKNOW; 431 tp->t_state = TCPS_SYN_RECEIVED; 432 tp->t_timer[TCPT_KEEP] = TCPTV_KEEP_INIT; 433 dropsocket = 0; /* committed to socket */ 434 tcpstat.tcps_accepts++; 435 goto trimthenstep6; 436 } 437 438 /* 439 * If the state is SYN_SENT: 440 * if seg contains an ACK, but not for our SYN, drop the input. 441 * if seg contains a RST, then drop the connection. 442 * if seg does not contain SYN, then drop it. 443 * Otherwise this is an acceptable SYN segment 444 * initialize tp->rcv_nxt and tp->irs 445 * if seg contains ack then advance tp->snd_una 446 * if SYN has been acked change to ESTABLISHED else SYN_RCVD state 447 * arrange for segment to be acked (eventually) 448 * continue processing rest of data/controls, beginning with URG 449 */ 450 case TCPS_SYN_SENT: 451 if ((tiflags & TH_ACK) && 452 (SEQ_LEQ(ti->ti_ack, tp->iss) || 453 SEQ_GT(ti->ti_ack, tp->snd_max))) 454 goto dropwithreset; 455 if (tiflags & TH_RST) { 456 if (tiflags & TH_ACK) 457 tp = tcp_drop(tp, ECONNREFUSED); 458 goto drop; 459 } 460 if ((tiflags & TH_SYN) == 0) 461 goto drop; 462 if (tiflags & TH_ACK) { 463 tp->snd_una = ti->ti_ack; 464 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 465 tp->snd_nxt = tp->snd_una; 466 } 467 tp->t_timer[TCPT_REXMT] = 0; 468 tp->irs = ti->ti_seq; 469 tcp_rcvseqinit(tp); 470 tp->t_flags |= TF_ACKNOW; 471 if (tiflags & TH_ACK && SEQ_GT(tp->snd_una, tp->iss)) { 472 tcpstat.tcps_connects++; 473 soisconnected(so); 474 tp->t_state = TCPS_ESTABLISHED; 475 tp->t_maxseg = MIN(tp->t_maxseg, tcp_mss(tp)); 476 (void) tcp_reass(tp, (struct tcpiphdr *)0); 477 /* 478 * if we didn't have to retransmit the SYN, 479 * use its rtt as our initial srtt & rtt var. 480 */ 481 if (tp->t_rtt) { 482 tp->t_srtt = tp->t_rtt << 3; 483 tp->t_rttvar = tp->t_rtt << 1; 484 TCPT_RANGESET(tp->t_rxtcur, 485 ((tp->t_srtt >> 2) + tp->t_rttvar) >> 1, 486 TCPTV_MIN, TCPTV_REXMTMAX); 487 tp->t_rtt = 0; 488 } 489 } else 490 tp->t_state = TCPS_SYN_RECEIVED; 491 492 trimthenstep6: 493 /* 494 * Advance ti->ti_seq to correspond to first data byte. 495 * If data, trim to stay within window, 496 * dropping FIN if necessary. 497 */ 498 ti->ti_seq++; 499 if (ti->ti_len > tp->rcv_wnd) { 500 todrop = ti->ti_len - tp->rcv_wnd; 501 #if BSD>=43 502 m_adj(m, -todrop); 503 #else 504 /* XXX work around 4.2 m_adj bug */ 505 if (m->m_len) { 506 m_adj(m, -todrop); 507 } else { 508 /* skip tcp/ip header in first mbuf */ 509 m_adj(m->m_next, -todrop); 510 } 511 #endif 512 ti->ti_len = tp->rcv_wnd; 513 tiflags &= ~TH_FIN; 514 tcpstat.tcps_rcvpackafterwin++; 515 tcpstat.tcps_rcvbyteafterwin += todrop; 516 } 517 tp->snd_wl1 = ti->ti_seq - 1; 518 tp->rcv_up = ti->ti_seq; 519 goto step6; 520 } 521 522 /* 523 * States other than LISTEN or SYN_SENT. 524 * First check that at least some bytes of segment are within 525 * receive window. If segment begins before rcv_nxt, 526 * drop leading data (and SYN); if nothing left, just ack. 527 */ 528 todrop = tp->rcv_nxt - ti->ti_seq; 529 if (todrop > 0) { 530 if (tiflags & TH_SYN) { 531 tiflags &= ~TH_SYN; 532 ti->ti_seq++; 533 if (ti->ti_urp > 1) 534 ti->ti_urp--; 535 else 536 tiflags &= ~TH_URG; 537 todrop--; 538 } 539 if (todrop > ti->ti_len || 540 todrop == ti->ti_len && (tiflags&TH_FIN) == 0) { 541 tcpstat.tcps_rcvduppack++; 542 tcpstat.tcps_rcvdupbyte += ti->ti_len; 543 /* 544 * If segment is just one to the left of the window, 545 * check two special cases: 546 * 1. Don't toss RST in response to 4.2-style keepalive. 547 * 2. If the only thing to drop is a FIN, we can drop 548 * it, but check the ACK or we will get into FIN 549 * wars if our FINs crossed (both CLOSING). 550 * In either case, send ACK to resynchronize, 551 * but keep on processing for RST or ACK. 552 */ 553 if ((tiflags & TH_FIN && todrop == ti->ti_len + 1) 554 #ifdef TCP_COMPAT_42 555 || (tiflags & TH_RST && ti->ti_seq == tp->rcv_nxt - 1) 556 #endif 557 ) { 558 todrop = ti->ti_len; 559 tiflags &= ~TH_FIN; 560 tp->t_flags |= TF_ACKNOW; 561 } else 562 goto dropafterack; 563 } else { 564 tcpstat.tcps_rcvpartduppack++; 565 tcpstat.tcps_rcvpartdupbyte += todrop; 566 } 567 m_adj(m, todrop); 568 ti->ti_seq += todrop; 569 ti->ti_len -= todrop; 570 if (ti->ti_urp > todrop) 571 ti->ti_urp -= todrop; 572 else { 573 tiflags &= ~TH_URG; 574 ti->ti_urp = 0; 575 } 576 } 577 578 /* 579 * If new data are received on a connection after the 580 * user processes are gone, then RST the other end. 581 */ 582 if ((so->so_state & SS_NOFDREF) && 583 tp->t_state > TCPS_CLOSE_WAIT && ti->ti_len) { 584 tp = tcp_close(tp); 585 tcpstat.tcps_rcvafterclose++; 586 goto dropwithreset; 587 } 588 589 /* 590 * If segment ends after window, drop trailing data 591 * (and PUSH and FIN); if nothing left, just ACK. 592 */ 593 todrop = (ti->ti_seq+ti->ti_len) - (tp->rcv_nxt+tp->rcv_wnd); 594 if (todrop > 0) { 595 tcpstat.tcps_rcvpackafterwin++; 596 if (todrop >= ti->ti_len) { 597 tcpstat.tcps_rcvbyteafterwin += ti->ti_len; 598 /* 599 * If a new connection request is received 600 * while in TIME_WAIT, drop the old connection 601 * and start over if the sequence numbers 602 * are above the previous ones. 603 */ 604 if (tiflags & TH_SYN && 605 tp->t_state == TCPS_TIME_WAIT && 606 SEQ_GT(ti->ti_seq, tp->rcv_nxt)) { 607 iss = tp->rcv_nxt + TCP_ISSINCR; 608 (void) tcp_close(tp); 609 goto findpcb; 610 } 611 /* 612 * If window is closed can only take segments at 613 * window edge, and have to drop data and PUSH from 614 * incoming segments. Continue processing, but 615 * remember to ack. Otherwise, drop segment 616 * and ack. 617 */ 618 if (tp->rcv_wnd == 0 && ti->ti_seq == tp->rcv_nxt) { 619 tp->t_flags |= TF_ACKNOW; 620 tcpstat.tcps_rcvwinprobe++; 621 } else 622 goto dropafterack; 623 } else 624 tcpstat.tcps_rcvbyteafterwin += todrop; 625 #if BSD>=43 626 m_adj(m, -todrop); 627 #else 628 /* XXX work around m_adj bug */ 629 if (m->m_len) { 630 m_adj(m, -todrop); 631 } else { 632 /* skip tcp/ip header in first mbuf */ 633 m_adj(m->m_next, -todrop); 634 } 635 #endif 636 ti->ti_len -= todrop; 637 tiflags &= ~(TH_PUSH|TH_FIN); 638 } 639 640 /* 641 * If the RST bit is set examine the state: 642 * SYN_RECEIVED STATE: 643 * If passive open, return to LISTEN state. 644 * If active open, inform user that connection was refused. 645 * ESTABLISHED, FIN_WAIT_1, FIN_WAIT2, CLOSE_WAIT STATES: 646 * Inform user that connection was reset, and close tcb. 647 * CLOSING, LAST_ACK, TIME_WAIT STATES 648 * Close the tcb. 649 */ 650 if (tiflags&TH_RST) switch (tp->t_state) { 651 652 case TCPS_SYN_RECEIVED: 653 so->so_error = ECONNREFUSED; 654 goto close; 655 656 case TCPS_ESTABLISHED: 657 case TCPS_FIN_WAIT_1: 658 case TCPS_FIN_WAIT_2: 659 case TCPS_CLOSE_WAIT: 660 so->so_error = ECONNRESET; 661 close: 662 tp->t_state = TCPS_CLOSED; 663 tcpstat.tcps_drops++; 664 tp = tcp_close(tp); 665 goto drop; 666 667 case TCPS_CLOSING: 668 case TCPS_LAST_ACK: 669 case TCPS_TIME_WAIT: 670 tp = tcp_close(tp); 671 goto drop; 672 } 673 674 /* 675 * If a SYN is in the window, then this is an 676 * error and we send an RST and drop the connection. 677 */ 678 if (tiflags & TH_SYN) { 679 tp = tcp_drop(tp, ECONNRESET); 680 goto dropwithreset; 681 } 682 683 /* 684 * If the ACK bit is off we drop the segment and return. 685 */ 686 if ((tiflags & TH_ACK) == 0) 687 goto drop; 688 689 /* 690 * Ack processing. 691 */ 692 switch (tp->t_state) { 693 694 /* 695 * In SYN_RECEIVED state if the ack ACKs our SYN then enter 696 * ESTABLISHED state and continue processing, otherwise 697 * send an RST. 698 */ 699 case TCPS_SYN_RECEIVED: 700 if (SEQ_GT(tp->snd_una, ti->ti_ack) || 701 SEQ_GT(ti->ti_ack, tp->snd_max)) 702 goto dropwithreset; 703 tcpstat.tcps_connects++; 704 soisconnected(so); 705 tp->t_state = TCPS_ESTABLISHED; 706 tp->t_maxseg = MIN(tp->t_maxseg, tcp_mss(tp)); 707 (void) tcp_reass(tp, (struct tcpiphdr *)0); 708 tp->snd_wl1 = ti->ti_seq - 1; 709 /* fall into ... */ 710 711 /* 712 * In ESTABLISHED state: drop duplicate ACKs; ACK out of range 713 * ACKs. If the ack is in the range 714 * tp->snd_una < ti->ti_ack <= tp->snd_max 715 * then advance tp->snd_una to ti->ti_ack and drop 716 * data from the retransmission queue. If this ACK reflects 717 * more up to date window information we update our window information. 718 */ 719 case TCPS_ESTABLISHED: 720 case TCPS_FIN_WAIT_1: 721 case TCPS_FIN_WAIT_2: 722 case TCPS_CLOSE_WAIT: 723 case TCPS_CLOSING: 724 case TCPS_LAST_ACK: 725 case TCPS_TIME_WAIT: 726 727 if (SEQ_LEQ(ti->ti_ack, tp->snd_una)) { 728 if (ti->ti_len == 0 && ti->ti_win == tp->snd_wnd) { 729 tcpstat.tcps_rcvdupack++; 730 /* 731 * If we have outstanding data (not a 732 * window probe), this is a completely 733 * duplicate ack (ie, window info didn't 734 * change), the ack is the biggest we've 735 * seen and we've seen exactly our rexmt 736 * threshhold of them, assume a packet 737 * has been dropped and retransmit it. 738 * Kludge snd_nxt & the congestion 739 * window so we send only this one 740 * packet. If this packet fills the 741 * only hole in the receiver's seq. 742 * space, the next real ack will fully 743 * open our window. This means we 744 * have to do the usual slow-start to 745 * not overwhelm an intermediate gateway 746 * with a burst of packets. Leave 747 * here with the congestion window set 748 * to allow 2 packets on the next real 749 * ack and the exp-to-linear thresh 750 * set for half the current window 751 * size (since we know we're losing at 752 * the current window size). 753 */ 754 if (tp->t_timer[TCPT_REXMT] == 0 || 755 ti->ti_ack != tp->snd_una) 756 tp->t_dupacks = 0; 757 else if (++tp->t_dupacks == tcprexmtthresh) { 758 tcp_seq onxt = tp->snd_nxt; 759 u_int win = 760 MIN(tp->snd_wnd, tp->snd_cwnd) / 2 / 761 tp->t_maxseg; 762 763 if (win < 2) 764 win = 2; 765 tp->snd_ssthresh = win * tp->t_maxseg; 766 767 tp->t_timer[TCPT_REXMT] = 0; 768 tp->t_rtt = 0; 769 tp->snd_nxt = ti->ti_ack; 770 tp->snd_cwnd = tp->t_maxseg; 771 (void) tcp_output(tp); 772 773 if (SEQ_GT(onxt, tp->snd_nxt)) 774 tp->snd_nxt = onxt; 775 goto drop; 776 } 777 } else 778 tp->t_dupacks = 0; 779 break; 780 } 781 tp->t_dupacks = 0; 782 if (SEQ_GT(ti->ti_ack, tp->snd_max)) { 783 tcpstat.tcps_rcvacktoomuch++; 784 goto dropafterack; 785 } 786 acked = ti->ti_ack - tp->snd_una; 787 tcpstat.tcps_rcvackpack++; 788 tcpstat.tcps_rcvackbyte += acked; 789 790 /* 791 * If transmit timer is running and timed sequence 792 * number was acked, update smoothed round trip time. 793 * Since we now have an rtt measurement, cancel the 794 * timer backoff (cf., Phil Karn's retransmit alg.). 795 * Recompute the initial retransmit timer. 796 */ 797 if (tp->t_rtt && SEQ_GT(ti->ti_ack, tp->t_rtseq)) { 798 tcpstat.tcps_rttupdated++; 799 if (tp->t_srtt != 0) { 800 register short delta; 801 802 /* 803 * srtt is stored as fixed point with 3 bits 804 * after the binary point (i.e., scaled by 8). 805 * The following magic is equivalent 806 * to the smoothing algorithm in rfc793 807 * with an alpha of .875 808 * (srtt = rtt/8 + srtt*7/8 in fixed point). 809 * Adjust t_rtt to origin 0. 810 */ 811 delta = tp->t_rtt - 1 - (tp->t_srtt >> 3); 812 if ((tp->t_srtt += delta) <= 0) 813 tp->t_srtt = 1; 814 /* 815 * We accumulate a smoothed rtt variance 816 * (actually, a smoothed mean difference), 817 * then set the retransmit timer to smoothed 818 * rtt + 2 times the smoothed variance. 819 * rttvar is stored as fixed point 820 * with 2 bits after the binary point 821 * (scaled by 4). The following is equivalent 822 * to rfc793 smoothing with an alpha of .75 823 * (rttvar = rttvar*3/4 + |delta| / 4). 824 * This replaces rfc793's wired-in beta. 825 */ 826 if (delta < 0) 827 delta = -delta; 828 delta -= (tp->t_rttvar >> 2); 829 if ((tp->t_rttvar += delta) <= 0) 830 tp->t_rttvar = 1; 831 } else { 832 /* 833 * No rtt measurement yet - use the 834 * unsmoothed rtt. Set the variance 835 * to half the rtt (so our first 836 * retransmit happens at 2*rtt) 837 */ 838 tp->t_srtt = tp->t_rtt << 3; 839 tp->t_rttvar = tp->t_rtt << 1; 840 } 841 tp->t_rtt = 0; 842 tp->t_rxtshift = 0; 843 TCPT_RANGESET(tp->t_rxtcur, 844 ((tp->t_srtt >> 2) + tp->t_rttvar) >> 1, 845 TCPTV_MIN, TCPTV_REXMTMAX); 846 } 847 848 /* 849 * If all outstanding data is acked, stop retransmit 850 * timer and remember to restart (more output or persist). 851 * If there is more data to be acked, restart retransmit 852 * timer, using current (possibly backed-off) value. 853 */ 854 if (ti->ti_ack == tp->snd_max) { 855 tp->t_timer[TCPT_REXMT] = 0; 856 needoutput = 1; 857 } else if (tp->t_timer[TCPT_PERSIST] == 0) 858 tp->t_timer[TCPT_REXMT] = tp->t_rxtcur; 859 /* 860 * When new data is acked, open the congestion window. 861 * If the window gives us less than ssthresh packets 862 * in flight, open exponentially (maxseg per packet). 863 * Otherwise open linearly (maxseg per window, 864 * or maxseg^2 / cwnd per packet). 865 */ 866 { 867 u_int incr = tp->t_maxseg; 868 869 if (tp->snd_cwnd > tp->snd_ssthresh) 870 incr = MAX(incr * incr / tp->snd_cwnd, 1); 871 872 tp->snd_cwnd = MIN(tp->snd_cwnd + incr, IP_MAXPACKET); /* XXX */ 873 } 874 if (acked > so->so_snd.sb_cc) { 875 tp->snd_wnd -= so->so_snd.sb_cc; 876 sbdrop(&so->so_snd, (int)so->so_snd.sb_cc); 877 ourfinisacked = 1; 878 } else { 879 sbdrop(&so->so_snd, acked); 880 tp->snd_wnd -= acked; 881 ourfinisacked = 0; 882 } 883 if ((so->so_snd.sb_flags & SB_WAIT) || so->so_snd.sb_sel) 884 sowwakeup(so); 885 tp->snd_una = ti->ti_ack; 886 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 887 tp->snd_nxt = tp->snd_una; 888 889 switch (tp->t_state) { 890 891 /* 892 * In FIN_WAIT_1 STATE in addition to the processing 893 * for the ESTABLISHED state if our FIN is now acknowledged 894 * then enter FIN_WAIT_2. 895 */ 896 case TCPS_FIN_WAIT_1: 897 if (ourfinisacked) { 898 /* 899 * If we can't receive any more 900 * data, then closing user can proceed. 901 * Starting the timer is contrary to the 902 * specification, but if we don't get a FIN 903 * we'll hang forever. 904 */ 905 if (so->so_state & SS_CANTRCVMORE) { 906 soisdisconnected(so); 907 tp->t_timer[TCPT_2MSL] = tcp_maxidle; 908 } 909 tp->t_state = TCPS_FIN_WAIT_2; 910 } 911 break; 912 913 /* 914 * In CLOSING STATE in addition to the processing for 915 * the ESTABLISHED state if the ACK acknowledges our FIN 916 * then enter the TIME-WAIT state, otherwise ignore 917 * the segment. 918 */ 919 case TCPS_CLOSING: 920 if (ourfinisacked) { 921 tp->t_state = TCPS_TIME_WAIT; 922 tcp_canceltimers(tp); 923 tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; 924 soisdisconnected(so); 925 } 926 break; 927 928 /* 929 * In LAST_ACK, we may still be waiting for data to drain 930 * and/or to be acked, as well as for the ack of our FIN. 931 * If our FIN is now acknowledged, delete the TCB, 932 * enter the closed state and return. 933 */ 934 case TCPS_LAST_ACK: 935 if (ourfinisacked) { 936 tp = tcp_close(tp); 937 goto drop; 938 } 939 break; 940 941 /* 942 * In TIME_WAIT state the only thing that should arrive 943 * is a retransmission of the remote FIN. Acknowledge 944 * it and restart the finack timer. 945 */ 946 case TCPS_TIME_WAIT: 947 tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; 948 goto dropafterack; 949 } 950 } 951 952 step6: 953 /* 954 * Update window information. 955 * Don't look at window if no ACK: TAC's send garbage on first SYN. 956 */ 957 if ((tiflags & TH_ACK) && 958 (SEQ_LT(tp->snd_wl1, ti->ti_seq) || tp->snd_wl1 == ti->ti_seq && 959 (SEQ_LT(tp->snd_wl2, ti->ti_ack) || 960 tp->snd_wl2 == ti->ti_ack && ti->ti_win > tp->snd_wnd))) { 961 /* keep track of pure window updates */ 962 if (ti->ti_len == 0 && 963 tp->snd_wl2 == ti->ti_ack && ti->ti_win > tp->snd_wnd) 964 tcpstat.tcps_rcvwinupd++; 965 tp->snd_wnd = ti->ti_win; 966 tp->snd_wl1 = ti->ti_seq; 967 tp->snd_wl2 = ti->ti_ack; 968 if (tp->snd_wnd > tp->max_sndwnd) 969 tp->max_sndwnd = tp->snd_wnd; 970 needoutput = 1; 971 } 972 973 /* 974 * Process segments with URG. 975 */ 976 if ((tiflags & TH_URG) && ti->ti_urp && 977 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 978 /* 979 * This is a kludge, but if we receive and accept 980 * random urgent pointers, we'll crash in 981 * soreceive. It's hard to imagine someone 982 * actually wanting to send this much urgent data. 983 */ 984 if (ti->ti_urp + so->so_rcv.sb_cc > SB_MAX) { 985 ti->ti_urp = 0; /* XXX */ 986 tiflags &= ~TH_URG; /* XXX */ 987 goto dodata; /* XXX */ 988 } 989 /* 990 * If this segment advances the known urgent pointer, 991 * then mark the data stream. This should not happen 992 * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since 993 * a FIN has been received from the remote side. 994 * In these states we ignore the URG. 995 * 996 * According to RFC961 (Assigned Protocols), 997 * the urgent pointer points to the last octet 998 * of urgent data. We continue, however, 999 * to consider it to indicate the first octet 1000 * of data past the urgent section 1001 * as the original spec states. 1002 */ 1003 if (SEQ_GT(ti->ti_seq+ti->ti_urp, tp->rcv_up)) { 1004 tp->rcv_up = ti->ti_seq + ti->ti_urp; 1005 so->so_oobmark = so->so_rcv.sb_cc + 1006 (tp->rcv_up - tp->rcv_nxt) - 1; 1007 if (so->so_oobmark == 0) 1008 so->so_state |= SS_RCVATMARK; 1009 sohasoutofband(so); 1010 tp->t_oobflags &= ~(TCPOOB_HAVEDATA | TCPOOB_HADDATA); 1011 } 1012 /* 1013 * Remove out of band data so doesn't get presented to user. 1014 * This can happen independent of advancing the URG pointer, 1015 * but if two URG's are pending at once, some out-of-band 1016 * data may creep in... ick. 1017 */ 1018 if (ti->ti_urp <= ti->ti_len 1019 #ifdef SO_OOBINLINE 1020 && (so->so_options & SO_OOBINLINE) == 0 1021 #endif 1022 ) 1023 tcp_pulloutofband(so, ti); 1024 } else 1025 /* 1026 * If no out of band data is expected, 1027 * pull receive urgent pointer along 1028 * with the receive window. 1029 */ 1030 if (SEQ_GT(tp->rcv_nxt, tp->rcv_up)) 1031 tp->rcv_up = tp->rcv_nxt; 1032 dodata: /* XXX */ 1033 1034 /* 1035 * Process the segment text, merging it into the TCP sequencing queue, 1036 * and arranging for acknowledgment of receipt if necessary. 1037 * This process logically involves adjusting tp->rcv_wnd as data 1038 * is presented to the user (this happens in tcp_usrreq.c, 1039 * case PRU_RCVD). If a FIN has already been received on this 1040 * connection then we just ignore the text. 1041 */ 1042 if ((ti->ti_len || (tiflags&TH_FIN)) && 1043 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 1044 TCP_REASS(tp, ti, m, so, tiflags); 1045 /* 1046 * Note the amount of data that peer has sent into 1047 * our window, in order to estimate the sender's 1048 * buffer size. 1049 */ 1050 len = so->so_rcv.sb_hiwat - (tp->rcv_adv - tp->rcv_nxt); 1051 if (len > tp->max_rcvd) 1052 tp->max_rcvd = len; 1053 } else { 1054 m_freem(m); 1055 tiflags &= ~TH_FIN; 1056 } 1057 1058 /* 1059 * If FIN is received ACK the FIN and let the user know 1060 * that the connection is closing. 1061 */ 1062 if (tiflags & TH_FIN) { 1063 if (TCPS_HAVERCVDFIN(tp->t_state) == 0) { 1064 socantrcvmore(so); 1065 tp->t_flags |= TF_ACKNOW; 1066 tp->rcv_nxt++; 1067 } 1068 switch (tp->t_state) { 1069 1070 /* 1071 * In SYN_RECEIVED and ESTABLISHED STATES 1072 * enter the CLOSE_WAIT state. 1073 */ 1074 case TCPS_SYN_RECEIVED: 1075 case TCPS_ESTABLISHED: 1076 tp->t_state = TCPS_CLOSE_WAIT; 1077 break; 1078 1079 /* 1080 * If still in FIN_WAIT_1 STATE FIN has not been acked so 1081 * enter the CLOSING state. 1082 */ 1083 case TCPS_FIN_WAIT_1: 1084 tp->t_state = TCPS_CLOSING; 1085 break; 1086 1087 /* 1088 * In FIN_WAIT_2 state enter the TIME_WAIT state, 1089 * starting the time-wait timer, turning off the other 1090 * standard timers. 1091 */ 1092 case TCPS_FIN_WAIT_2: 1093 tp->t_state = TCPS_TIME_WAIT; 1094 tcp_canceltimers(tp); 1095 tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; 1096 soisdisconnected(so); 1097 break; 1098 1099 /* 1100 * In TIME_WAIT state restart the 2 MSL time_wait timer. 1101 */ 1102 case TCPS_TIME_WAIT: 1103 tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; 1104 break; 1105 } 1106 } 1107 if (so->so_options & SO_DEBUG) 1108 tcp_trace(TA_INPUT, ostate, tp, &tcp_saveti, 0); 1109 1110 /* 1111 * Return any desired output. 1112 */ 1113 if (needoutput || (tp->t_flags & TF_ACKNOW)) 1114 (void) tcp_output(tp); 1115 return; 1116 1117 dropafterack: 1118 /* 1119 * Generate an ACK dropping incoming segment if it occupies 1120 * sequence space, where the ACK reflects our state. 1121 */ 1122 if (tiflags & TH_RST) 1123 goto drop; 1124 m_freem(m); 1125 tp->t_flags |= TF_ACKNOW; 1126 (void) tcp_output(tp); 1127 return; 1128 1129 dropwithreset: 1130 if (om) { 1131 (void) m_free(om); 1132 om = 0; 1133 } 1134 /* 1135 * Generate a RST, dropping incoming segment. 1136 * Make ACK acceptable to originator of segment. 1137 * Don't bother to respond if destination was broadcast. 1138 */ 1139 if ((tiflags & TH_RST) || in_broadcast(ti->ti_dst)) 1140 goto drop; 1141 if (tiflags & TH_ACK) 1142 tcp_respond(tp, ti, (tcp_seq)0, ti->ti_ack, TH_RST); 1143 else { 1144 if (tiflags & TH_SYN) 1145 ti->ti_len++; 1146 tcp_respond(tp, ti, ti->ti_seq+ti->ti_len, (tcp_seq)0, 1147 TH_RST|TH_ACK); 1148 } 1149 /* destroy temporarily created socket */ 1150 if (dropsocket) 1151 (void) soabort(so); 1152 return; 1153 1154 drop: 1155 if (om) 1156 (void) m_free(om); 1157 /* 1158 * Drop space held by incoming segment and return. 1159 */ 1160 if (tp && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) 1161 tcp_trace(TA_DROP, ostate, tp, &tcp_saveti, 0); 1162 m_freem(m); 1163 /* destroy temporarily created socket */ 1164 if (dropsocket) 1165 (void) soabort(so); 1166 return; 1167 } 1168 1169 tcp_dooptions(tp, om, ti) 1170 struct tcpcb *tp; 1171 struct mbuf *om; 1172 struct tcpiphdr *ti; 1173 { 1174 register u_char *cp; 1175 int opt, optlen, cnt; 1176 1177 cp = mtod(om, u_char *); 1178 cnt = om->m_len; 1179 for (; cnt > 0; cnt -= optlen, cp += optlen) { 1180 opt = cp[0]; 1181 if (opt == TCPOPT_EOL) 1182 break; 1183 if (opt == TCPOPT_NOP) 1184 optlen = 1; 1185 else { 1186 optlen = cp[1]; 1187 if (optlen <= 0) 1188 break; 1189 } 1190 switch (opt) { 1191 1192 default: 1193 break; 1194 1195 case TCPOPT_MAXSEG: 1196 if (optlen != 4) 1197 continue; 1198 if (!(ti->ti_flags & TH_SYN)) 1199 continue; 1200 tp->t_maxseg = *(u_short *)(cp + 2); 1201 tp->t_maxseg = ntohs((u_short)tp->t_maxseg); 1202 tp->t_maxseg = MIN(tp->t_maxseg, tcp_mss(tp)); 1203 break; 1204 } 1205 } 1206 (void) m_free(om); 1207 } 1208 1209 /* 1210 * Pull out of band byte out of a segment so 1211 * it doesn't appear in the user's data queue. 1212 * It is still reflected in the segment length for 1213 * sequencing purposes. 1214 */ 1215 tcp_pulloutofband(so, ti) 1216 struct socket *so; 1217 struct tcpiphdr *ti; 1218 { 1219 register struct mbuf *m; 1220 int cnt = ti->ti_urp - 1; 1221 1222 m = dtom(ti); 1223 while (cnt >= 0) { 1224 if (m->m_len > cnt) { 1225 char *cp = mtod(m, caddr_t) + cnt; 1226 struct tcpcb *tp = sototcpcb(so); 1227 1228 tp->t_iobc = *cp; 1229 tp->t_oobflags |= TCPOOB_HAVEDATA; 1230 bcopy(cp+1, cp, (unsigned)(m->m_len - cnt - 1)); 1231 m->m_len--; 1232 return; 1233 } 1234 cnt -= m->m_len; 1235 m = m->m_next; 1236 if (m == 0) 1237 break; 1238 } 1239 panic("tcp_pulloutofband"); 1240 } 1241 1242 /* 1243 * Determine a reasonable value for maxseg size. 1244 * If the route is known, use one that can be handled 1245 * on the given interface without forcing IP to fragment. 1246 * If bigger than an mbuf cluster (MCLBYTES), round down to nearest size 1247 * to utilize large mbufs. 1248 * If interface pointer is unavailable, or the destination isn't local, 1249 * use a conservative size (512 or the default IP max size, but no more 1250 * than the mtu of the interface through which we route), 1251 * as we can't discover anything about intervening gateways or networks. 1252 * We also initialize the congestion/slow start window to be a single 1253 * segment if the destination isn't local; this information should 1254 * probably all be saved with the routing entry at the transport level. 1255 * 1256 * This is ugly, and doesn't belong at this level, but has to happen somehow. 1257 */ 1258 tcp_mss(tp) 1259 register struct tcpcb *tp; 1260 { 1261 struct route *ro; 1262 struct ifnet *ifp; 1263 int mss; 1264 struct inpcb *inp; 1265 1266 inp = tp->t_inpcb; 1267 ro = &inp->inp_route; 1268 if ((ro->ro_rt == (struct rtentry *)0) || 1269 (ifp = ro->ro_rt->rt_ifp) == (struct ifnet *)0) { 1270 /* No route yet, so try to acquire one */ 1271 if (inp->inp_faddr.s_addr != INADDR_ANY) { 1272 ro->ro_dst.sa_family = AF_INET; 1273 ((struct sockaddr_in *) &ro->ro_dst)->sin_addr = 1274 inp->inp_faddr; 1275 rtalloc(ro); 1276 } 1277 if ((ro->ro_rt == 0) || (ifp = ro->ro_rt->rt_ifp) == 0) 1278 return (TCP_MSS); 1279 } 1280 1281 mss = ifp->if_mtu - sizeof(struct tcpiphdr); 1282 #if (MCLBYTES & (MCLBYTES - 1)) == 0 1283 if (mss > MCLBYTES) 1284 mss &= ~(MCLBYTES-1); 1285 #else 1286 if (mss > MCLBYTES) 1287 mss = mss / MCLBYTES * MCLBYTES; 1288 #endif 1289 if (in_localaddr(inp->inp_faddr)) 1290 return (mss); 1291 1292 mss = MIN(mss, TCP_MSS); 1293 tp->snd_cwnd = mss; 1294 return (mss); 1295 } 1296 1297 #if BSD<43 1298 /* XXX this belongs in netinet/in.c */ 1299 in_localaddr(in) 1300 struct in_addr in; 1301 { 1302 register u_long i = ntohl(in.s_addr); 1303 register struct ifnet *ifp; 1304 register struct sockaddr_in *sin; 1305 register u_long mask; 1306 1307 if (IN_CLASSA(i)) 1308 mask = IN_CLASSA_NET; 1309 else if (IN_CLASSB(i)) 1310 mask = IN_CLASSB_NET; 1311 else if (IN_CLASSC(i)) 1312 mask = IN_CLASSC_NET; 1313 else 1314 return (0); 1315 1316 i &= mask; 1317 for (ifp = ifnet; ifp; ifp = ifp->if_next) { 1318 if (ifp->if_addr.sa_family != AF_INET) 1319 continue; 1320 sin = (struct sockaddr_in *)&ifp->if_addr; 1321 if ((sin->sin_addr.s_addr & mask) == i) 1322 return (1); 1323 } 1324 return (0); 1325 } 1326 #endif 1327