1 /* tcp_input.c 1.74 82/09/26 */ 2 3 #include "../h/param.h" 4 #include "../h/systm.h" 5 #include "../h/mbuf.h" 6 #include "../h/protosw.h" 7 #include "../h/socket.h" 8 #include "../h/socketvar.h" 9 #include "../net/in.h" 10 #include "../net/route.h" 11 #include "../net/in_pcb.h" 12 #include "../net/in_systm.h" 13 #include "../net/if.h" 14 #include "../net/ip.h" 15 #include "../net/ip_var.h" 16 #include "../net/tcp.h" 17 #include "../net/tcp_fsm.h" 18 #include "../net/tcp_seq.h" 19 #include "../net/tcp_timer.h" 20 #include "../net/tcp_var.h" 21 #include "../net/tcpip.h" 22 #include "../net/tcp_debug.h" 23 #include <errno.h> 24 25 int tcpprintfs = 0; 26 int tcpcksum = 1; 27 struct mbuf tcp_mb; 28 struct tcpiphdr tcp_saveti; 29 extern tcpnodelack; 30 31 struct tcpcb *tcp_newtcpcb(); 32 /* 33 * TCP input routine, follows pages 65-76 of the 34 * protocol specification dated September, 1981 very closely. 35 */ 36 tcp_input(m0) 37 struct mbuf *m0; 38 { 39 register struct tcpiphdr *ti; 40 struct inpcb *inp; 41 register struct mbuf *m; 42 struct mbuf *om = 0; 43 int len, tlen, off; 44 register struct tcpcb *tp = 0; 45 register int tiflags; 46 struct socket *so; 47 int todrop, acked; 48 short ostate; 49 struct in_addr laddr; 50 51 /* 52 * Get IP and TCP header together in first mbuf. 53 * Note: IP leaves IP header in first mbuf. 54 */ 55 m = m0; 56 ti = mtod(m, struct tcpiphdr *); 57 if (((struct ip *)ti)->ip_hl > (sizeof (struct ip) >> 2)) 58 ip_stripoptions((struct ip *)ti, (struct mbuf *)0); 59 if (m->m_off > MMAXOFF || m->m_len < sizeof (struct tcpiphdr)) { 60 if ((m = m_pullup(m, sizeof (struct tcpiphdr))) == 0) { 61 tcpstat.tcps_hdrops++; 62 return; 63 } 64 ti = mtod(m, struct tcpiphdr *); 65 } 66 67 /* 68 * Checksum extended TCP header and data. 69 */ 70 tlen = ((struct ip *)ti)->ip_len; 71 len = sizeof (struct ip) + tlen; 72 if (tcpcksum) { 73 ti->ti_next = ti->ti_prev = 0; 74 ti->ti_x1 = 0; 75 ti->ti_len = (u_short)tlen; 76 #if vax || pdp11 77 ti->ti_len = htons((u_short)ti->ti_len); 78 #endif 79 if (ti->ti_sum = in_cksum(m, len)) { 80 tcpstat.tcps_badsum++; 81 if (tcpprintfs) 82 printf("tcp cksum %x\n", ti->ti_sum); 83 goto drop; 84 } 85 } 86 87 /* 88 * Check that TCP offset makes sense, 89 * pull out TCP options and adjust length. 90 */ 91 off = ti->ti_off << 2; 92 if (off < sizeof (struct tcphdr) || off > tlen) { 93 tcpstat.tcps_badoff++; 94 goto drop; 95 } 96 tlen -= off; 97 ti->ti_len = tlen; 98 if (off > sizeof (struct tcphdr)) { 99 if ((m = m_pullup(m, sizeof (struct ip) + off)) == 0) { 100 tcpstat.tcps_hdrops++; 101 goto drop; 102 } 103 ti = mtod(m, struct tcpiphdr *); 104 om = m_get(M_DONTWAIT); 105 if (om == 0) 106 goto drop; 107 om->m_off = MMINOFF; 108 om->m_len = off - sizeof (struct tcphdr); 109 { caddr_t op = mtod(m, caddr_t) + sizeof (struct tcpiphdr); 110 bcopy(op, mtod(om, caddr_t), (unsigned)om->m_len); 111 m->m_len -= om->m_len; 112 bcopy(op+om->m_len, op, 113 (unsigned)(m->m_len-sizeof (struct tcpiphdr))); 114 } 115 } 116 tiflags = ti->ti_flags; 117 118 /* 119 * Drop TCP and IP headers. 120 */ 121 off += sizeof (struct ip); 122 m->m_off += off; 123 m->m_len -= off; 124 125 #if vax || pdp11 126 /* 127 * Convert TCP protocol specific fields to host format. 128 */ 129 ti->ti_seq = ntohl(ti->ti_seq); 130 ti->ti_ack = ntohl(ti->ti_ack); 131 ti->ti_win = ntohs(ti->ti_win); 132 ti->ti_urp = ntohs(ti->ti_urp); 133 #endif 134 135 /* 136 * Locate pcb for segment. 137 */ 138 inp = in_pcblookup 139 (&tcb, ti->ti_src, ti->ti_sport, ti->ti_dst, ti->ti_dport, 140 INPLOOKUP_WILDCARD); 141 142 /* 143 * If the state is CLOSED (i.e., TCB does not exist) then 144 * all data in the incoming segment is discarded. 145 */ 146 if (inp == 0) 147 goto dropwithreset; 148 tp = intotcpcb(inp); 149 if (tp == 0) 150 goto dropwithreset; 151 so = inp->inp_socket; 152 if (so->so_options & SO_DEBUG) { 153 ostate = tp->t_state; 154 tcp_saveti = *ti; 155 } 156 if (so->so_options & SO_ACCEPTCONN) { 157 so = sonewconn(so); 158 if (so == 0) 159 goto drop; 160 inp = (struct inpcb *)so->so_pcb; 161 inp->inp_laddr = ti->ti_dst; 162 inp->inp_lport = ti->ti_dport; 163 tp = intotcpcb(inp); 164 tp->t_state = TCPS_LISTEN; 165 } 166 167 /* 168 * Segment received on connection. 169 * Reset idle time and keep-alive timer. 170 */ 171 tp->t_idle = 0; 172 tp->t_timer[TCPT_KEEP] = TCPTV_KEEP; 173 174 /* 175 * Process options. 176 */ 177 if (om) { 178 tcp_dooptions(tp, om); 179 om = 0; 180 } 181 182 /* 183 * Calculate amount of space in receive window, 184 * and then do TCP input processing. 185 */ 186 tp->rcv_wnd = sbspace(&so->so_rcv); 187 if (tp->rcv_wnd < 0) 188 tp->rcv_wnd = 0; 189 190 switch (tp->t_state) { 191 192 /* 193 * If the state is LISTEN then ignore segment if it contains an RST. 194 * If the segment contains an ACK then it is bad and send a RST. 195 * If it does not contain a SYN then it is not interesting; drop it. 196 * Otherwise initialize tp->rcv_nxt, and tp->irs, select an initial 197 * tp->iss, and send a segment: 198 * <SEQ=ISS><ACK=RCV_NXT><CTL=SYN,ACK> 199 * Also initialize tp->snd_nxt to tp->iss+1 and tp->snd_una to tp->iss. 200 * Fill in remote peer address fields if not previously specified. 201 * Enter SYN_RECEIVED state, and process any other fields of this 202 * segment in this state. 203 */ 204 case TCPS_LISTEN: { 205 struct mbuf *m = m_get(M_DONTWAIT); 206 register struct sockaddr_in *sin; 207 208 if (m == 0) 209 goto drop; 210 m->m_off = MMINOFF; 211 m->m_len = sizeof (struct sockaddr_in); 212 if (tiflags & TH_RST) 213 goto drop; 214 if (tiflags & TH_ACK) 215 goto dropwithreset; 216 if ((tiflags & TH_SYN) == 0) 217 goto drop; 218 sin = mtod(m, struct sockaddr_in *); 219 sin->sin_family = AF_INET; 220 sin->sin_addr = ti->ti_src; 221 sin->sin_port = ti->ti_sport; 222 laddr = inp->inp_laddr; 223 if (inp->inp_laddr.s_addr == 0) 224 inp->inp_laddr = ti->ti_dst; 225 if (in_pcbconnect(inp, m)) { 226 inp->inp_laddr = laddr; 227 m_free(m); 228 goto drop; 229 } 230 m_free(m); 231 tp->t_template = tcp_template(tp); 232 if (tp->t_template == 0) { 233 in_pcbdisconnect(inp); 234 inp->inp_laddr = laddr; 235 tp = 0; 236 goto drop; 237 } 238 tp->iss = tcp_iss; tcp_iss += TCP_ISSINCR/2; 239 tp->irs = ti->ti_seq; 240 tcp_sendseqinit(tp); 241 tcp_rcvseqinit(tp); 242 tp->t_state = TCPS_SYN_RECEIVED; 243 tp->t_timer[TCPT_KEEP] = TCPTV_KEEP; 244 goto trimthenstep6; 245 } 246 247 /* 248 * If the state is SYN_SENT: 249 * if seg contains an ACK, but not for our SYN, drop the input. 250 * if seg contains a RST, then drop the connection. 251 * if seg does not contain SYN, then drop it. 252 * Otherwise this is an acceptable SYN segment 253 * initialize tp->rcv_nxt and tp->irs 254 * if seg contains ack then advance tp->snd_una 255 * if SYN has been acked change to ESTABLISHED else SYN_RCVD state 256 * arrange for segment to be acked (eventually) 257 * continue processing rest of data/controls, beginning with URG 258 */ 259 case TCPS_SYN_SENT: 260 if ((tiflags & TH_ACK) && 261 /* this should be SEQ_LT; is SEQ_LEQ for BBN vax TCP only */ 262 (SEQ_LT(ti->ti_ack, tp->iss) || 263 SEQ_GT(ti->ti_ack, tp->snd_max))) 264 goto dropwithreset; 265 if (tiflags & TH_RST) { 266 if (tiflags & TH_ACK) { 267 tcp_drop(tp, ECONNREFUSED); 268 tp = 0; 269 } 270 goto drop; 271 } 272 if ((tiflags & TH_SYN) == 0) 273 goto drop; 274 tp->snd_una = ti->ti_ack; 275 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 276 tp->snd_nxt = tp->snd_una; 277 tp->t_timer[TCPT_REXMT] = 0; 278 tp->irs = ti->ti_seq; 279 tcp_rcvseqinit(tp); 280 tp->t_flags |= TF_ACKNOW; 281 if (SEQ_GT(tp->snd_una, tp->iss)) { 282 soisconnected(so); 283 tp->t_state = TCPS_ESTABLISHED; 284 (void) tcp_reass(tp, (struct tcpiphdr *)0); 285 } else 286 tp->t_state = TCPS_SYN_RECEIVED; 287 goto trimthenstep6; 288 289 trimthenstep6: 290 /* 291 * Advance ti->ti_seq to correspond to first data byte. 292 * If data, trim to stay within window, 293 * dropping FIN if necessary. 294 */ 295 ti->ti_seq++; 296 if (ti->ti_len > tp->rcv_wnd) { 297 todrop = ti->ti_len - tp->rcv_wnd; 298 m_adj(m, -todrop); 299 ti->ti_len = tp->rcv_wnd; 300 ti->ti_flags &= ~TH_FIN; 301 } 302 tp->snd_wl1 = ti->ti_seq - 1; 303 goto step6; 304 } 305 306 /* 307 * States other than LISTEN or SYN_SENT. 308 * First check that at least some bytes of segment are within 309 * receive window. 310 */ 311 if (tp->rcv_wnd == 0) { 312 /* 313 * If window is closed can only take segments at 314 * window edge, and have to drop data and PUSH from 315 * incoming segments. 316 */ 317 if (tp->rcv_nxt != ti->ti_seq) 318 goto dropafterack; 319 if (ti->ti_len > 0) { 320 m_adj(m, ti->ti_len); 321 ti->ti_len = 0; 322 ti->ti_flags &= ~(TH_PUSH|TH_FIN); 323 } 324 } else { 325 /* 326 * If segment begins before rcv_nxt, drop leading 327 * data (and SYN); if nothing left, just ack. 328 */ 329 todrop = tp->rcv_nxt - ti->ti_seq; 330 if (todrop > 0) { 331 if (tiflags & TH_SYN) { 332 tiflags &= ~TH_SYN; 333 ti->ti_flags &= ~TH_SYN; 334 ti->ti_seq++; 335 if (ti->ti_urp > 1) 336 ti->ti_urp--; 337 else 338 tiflags &= ~TH_URG; 339 todrop--; 340 } 341 if (todrop > ti->ti_len || 342 todrop == ti->ti_len && (tiflags&TH_FIN) == 0) 343 goto dropafterack; 344 m_adj(m, todrop); 345 ti->ti_seq += todrop; 346 ti->ti_len -= todrop; 347 if (ti->ti_urp > todrop) 348 ti->ti_urp -= todrop; 349 else { 350 tiflags &= ~TH_URG; 351 ti->ti_flags &= ~TH_URG; 352 ti->ti_urp = 0; 353 } 354 } 355 /* 356 * If segment ends after window, drop trailing data 357 * (and PUSH and FIN); if nothing left, just ACK. 358 */ 359 todrop = (ti->ti_seq+ti->ti_len) - (tp->rcv_nxt+tp->rcv_wnd); 360 if (todrop > 0) { 361 if (todrop >= ti->ti_len) 362 goto dropafterack; 363 m_adj(m, -todrop); 364 ti->ti_len -= todrop; 365 ti->ti_flags &= ~(TH_PUSH|TH_FIN); 366 } 367 } 368 369 /* 370 * If a segment is received on a connection after the 371 * user processes are gone, then RST the other end. 372 */ 373 if (so->so_state & SS_NOFDREF) { 374 tcp_close(tp); 375 tp = 0; 376 goto dropwithreset; 377 } 378 379 /* 380 * If the RST bit is set examine the state: 381 * SYN_RECEIVED STATE: 382 * If passive open, return to LISTEN state. 383 * If active open, inform user that connection was refused. 384 * ESTABLISHED, FIN_WAIT_1, FIN_WAIT2, CLOSE_WAIT STATES: 385 * Inform user that connection was reset, and close tcb. 386 * CLOSING, LAST_ACK, TIME_WAIT STATES 387 * Close the tcb. 388 */ 389 if (tiflags&TH_RST) switch (tp->t_state) { 390 391 case TCPS_SYN_RECEIVED: 392 tcp_drop(tp, ECONNREFUSED); 393 tp = 0; 394 goto drop; 395 396 case TCPS_ESTABLISHED: 397 case TCPS_FIN_WAIT_1: 398 case TCPS_FIN_WAIT_2: 399 case TCPS_CLOSE_WAIT: 400 tcp_drop(tp, ECONNRESET); 401 tp = 0; 402 goto drop; 403 404 case TCPS_CLOSING: 405 case TCPS_LAST_ACK: 406 case TCPS_TIME_WAIT: 407 tcp_close(tp); 408 tp = 0; 409 goto drop; 410 } 411 412 /* 413 * If a SYN is in the window, then this is an 414 * error and we send an RST and drop the connection. 415 */ 416 if (tiflags & TH_SYN) { 417 tcp_drop(tp, ECONNRESET); 418 tp = 0; 419 goto dropwithreset; 420 } 421 422 /* 423 * If the ACK bit is off we drop the segment and return. 424 */ 425 if ((tiflags & TH_ACK) == 0) 426 goto drop; 427 428 /* 429 * Ack processing. 430 */ 431 switch (tp->t_state) { 432 433 /* 434 * In SYN_RECEIVED state if the ack ACKs our SYN then enter 435 * ESTABLISHED state and continue processing, othewise 436 * send an RST. 437 */ 438 case TCPS_SYN_RECEIVED: 439 if (SEQ_GT(tp->snd_una, ti->ti_ack) || 440 SEQ_GT(ti->ti_ack, tp->snd_max)) 441 goto dropwithreset; 442 tp->snd_una++; /* SYN acked */ 443 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 444 tp->snd_nxt = tp->snd_una; 445 tp->t_timer[TCPT_REXMT] = 0; 446 soisconnected(so); 447 tp->t_state = TCPS_ESTABLISHED; 448 (void) tcp_reass(tp, (struct tcpiphdr *)0); 449 tp->snd_wl1 = ti->ti_seq - 1; 450 /* fall into ... */ 451 452 /* 453 * In ESTABLISHED state: drop duplicate ACKs; ACK out of range 454 * ACKs. If the ack is in the range 455 * tp->snd_una < ti->ti_ack <= tp->snd_max 456 * then advance tp->snd_una to ti->ti_ack and drop 457 * data from the retransmission queue. If this ACK reflects 458 * more up to date window information we update our window information. 459 */ 460 case TCPS_ESTABLISHED: 461 case TCPS_FIN_WAIT_1: 462 case TCPS_FIN_WAIT_2: 463 case TCPS_CLOSE_WAIT: 464 case TCPS_CLOSING: 465 case TCPS_LAST_ACK: 466 case TCPS_TIME_WAIT: 467 #define ourfinisacked (acked > 0) 468 469 if (SEQ_LEQ(ti->ti_ack, tp->snd_una)) 470 break; 471 if (SEQ_GT(ti->ti_ack, tp->snd_max)) 472 goto dropafterack; 473 acked = ti->ti_ack - tp->snd_una; 474 475 /* 476 * If transmit timer is running and timed sequence 477 * number was acked, update smoothed round trip time. 478 */ 479 if (tp->t_rtt && SEQ_GT(ti->ti_ack, tp->t_rtseq)) { 480 if (tp->t_srtt == 0) 481 tp->t_srtt = tp->t_rtt; 482 else 483 tp->t_srtt = 484 tcp_alpha * tp->t_srtt + 485 (1 - tcp_alpha) * tp->t_rtt; 486 /* printf("rtt %d srtt*100 now %d\n", tp->t_rtt, (int)(tp->t_srtt*100)); */ 487 tp->t_rtt = 0; 488 } 489 490 if (ti->ti_ack == tp->snd_max) 491 tp->t_timer[TCPT_REXMT] = 0; 492 else { 493 TCPT_RANGESET(tp->t_timer[TCPT_REXMT], 494 tcp_beta * tp->t_srtt, TCPTV_MIN, TCPTV_MAX); 495 tp->t_rtt = 1; 496 tp->t_rxtshift = 0; 497 } 498 if (acked > so->so_snd.sb_cc) { 499 sbdrop(&so->so_snd, so->so_snd.sb_cc); 500 tp->snd_wnd -= so->so_snd.sb_cc; 501 } else { 502 sbdrop(&so->so_snd, acked); 503 tp->snd_wnd -= acked; 504 acked = 0; 505 } 506 if ((so->so_snd.sb_flags & SB_WAIT) || so->so_snd.sb_sel) 507 sowwakeup(so); 508 tp->snd_una = ti->ti_ack; 509 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 510 tp->snd_nxt = tp->snd_una; 511 512 switch (tp->t_state) { 513 514 /* 515 * In FIN_WAIT_1 STATE in addition to the processing 516 * for the ESTABLISHED state if our FIN is now acknowledged 517 * then enter FIN_WAIT_2. 518 */ 519 case TCPS_FIN_WAIT_1: 520 if (ourfinisacked) { 521 /* 522 * If we can't receive any more 523 * data, then closing user can proceed. 524 */ 525 if (so->so_state & SS_CANTRCVMORE) 526 soisdisconnected(so); 527 tp->t_state = TCPS_FIN_WAIT_2; 528 } 529 break; 530 531 /* 532 * In CLOSING STATE in addition to the processing for 533 * the ESTABLISHED state if the ACK acknowledges our FIN 534 * then enter the TIME-WAIT state, otherwise ignore 535 * the segment. 536 */ 537 case TCPS_CLOSING: 538 if (ourfinisacked) { 539 tp->t_state = TCPS_TIME_WAIT; 540 tcp_canceltimers(tp); 541 tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; 542 soisdisconnected(so); 543 } 544 break; 545 546 /* 547 * The only thing that can arrive in LAST_ACK state 548 * is an acknowledgment of our FIN. If our FIN is now 549 * acknowledged, delete the TCB, enter the closed state 550 * and return. 551 */ 552 case TCPS_LAST_ACK: 553 if (ourfinisacked) { 554 tcp_close(tp); 555 tp = 0; 556 } 557 goto drop; 558 559 /* 560 * In TIME_WAIT state the only thing that should arrive 561 * is a retransmission of the remote FIN. Acknowledge 562 * it and restart the finack timer. 563 */ 564 case TCPS_TIME_WAIT: 565 tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; 566 goto dropafterack; 567 } 568 #undef ourfinisacked 569 } 570 571 step6: 572 /* 573 * Update window information. 574 */ 575 if (SEQ_LT(tp->snd_wl1, ti->ti_seq) || tp->snd_wl1 == ti->ti_seq && 576 (SEQ_LT(tp->snd_wl2, ti->ti_ack) || 577 tp->snd_wl2 == ti->ti_ack && ti->ti_win > tp->snd_wnd)) { 578 tp->snd_wnd = ti->ti_win; 579 tp->snd_wl1 = ti->ti_seq; 580 tp->snd_wl2 = ti->ti_ack; 581 if (tp->snd_wnd > 0) 582 tp->t_timer[TCPT_PERSIST] = 0; 583 } 584 585 /* 586 * Process segments with URG. 587 */ 588 if ((tiflags & TH_URG) && ti->ti_urp && 589 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 590 /* 591 * If this segment advances the known urgent pointer, 592 * then mark the data stream. This should not happen 593 * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since 594 * a FIN has been received from the remote side. 595 * In these states we ignore the URG. 596 */ 597 if (SEQ_GT(ti->ti_seq+ti->ti_urp, tp->rcv_up)) { 598 tp->rcv_up = ti->ti_seq + ti->ti_urp; 599 so->so_oobmark = so->so_rcv.sb_cc + 600 (tp->rcv_up - tp->rcv_nxt) - 1; 601 if (so->so_oobmark == 0) 602 so->so_state |= SS_RCVATMARK; 603 #ifdef TCPTRUEOOB 604 if ((tp->t_flags & TF_DOOOB) == 0) 605 #endif 606 sohasoutofband(so); 607 tp->t_oobflags &= ~TCPOOB_HAVEDATA; 608 } 609 /* 610 * Remove out of band data so doesn't get presented to user. 611 * This can happen independent of advancing the URG pointer, 612 * but if two URG's are pending at once, some out-of-band 613 * data may creep in... ick. 614 */ 615 if (ti->ti_urp <= ti->ti_len) 616 tcp_pulloutofband(so, ti); 617 } 618 619 /* 620 * Process the segment text, merging it into the TCP sequencing queue, 621 * and arranging for acknowledgment of receipt if necessary. 622 * This process logically involves adjusting tp->rcv_wnd as data 623 * is presented to the user (this happens in tcp_usrreq.c, 624 * case PRU_RCVD). If a FIN has already been received on this 625 * connection then we just ignore the text. 626 */ 627 if ((ti->ti_len || (tiflags&TH_FIN)) && 628 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 629 tiflags = tcp_reass(tp, ti); 630 if (tcpnodelack == 0) 631 tp->t_flags |= TF_DELACK; 632 else 633 tp->t_flags |= TF_ACKNOW; 634 } else { 635 m_freem(m); 636 tiflags &= ~TH_FIN; 637 } 638 639 /* 640 * If FIN is received ACK the FIN and let the user know 641 * that the connection is closing. 642 */ 643 if (tiflags & TH_FIN) { 644 if (TCPS_HAVERCVDFIN(tp->t_state) == 0) { 645 socantrcvmore(so); 646 tp->t_flags |= TF_ACKNOW; 647 tp->rcv_nxt++; 648 } 649 switch (tp->t_state) { 650 651 /* 652 * In SYN_RECEIVED and ESTABLISHED STATES 653 * enter the CLOSE_WAIT state. 654 */ 655 case TCPS_SYN_RECEIVED: 656 case TCPS_ESTABLISHED: 657 tp->t_state = TCPS_CLOSE_WAIT; 658 break; 659 660 /* 661 * If still in FIN_WAIT_1 STATE FIN has not been acked so 662 * enter the CLOSING state. 663 */ 664 case TCPS_FIN_WAIT_1: 665 tp->t_state = TCPS_CLOSING; 666 break; 667 668 /* 669 * In FIN_WAIT_2 state enter the TIME_WAIT state, 670 * starting the time-wait timer, turning off the other 671 * standard timers. 672 */ 673 case TCPS_FIN_WAIT_2: 674 tp->t_state = TCPS_TIME_WAIT; 675 tcp_canceltimers(tp); 676 tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; 677 soisdisconnected(so); 678 break; 679 680 /* 681 * In TIME_WAIT state restart the 2 MSL time_wait timer. 682 */ 683 case TCPS_TIME_WAIT: 684 tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; 685 break; 686 } 687 } 688 if (so->so_options & SO_DEBUG) 689 tcp_trace(TA_INPUT, ostate, tp, &tcp_saveti, 0); 690 691 /* 692 * Return any desired output. 693 */ 694 (void) tcp_output(tp); 695 return; 696 697 dropafterack: 698 /* 699 * Generate an ACK dropping incoming segment if it occupies 700 * sequence space, where the ACK reflects our state. 701 */ 702 if ((tiflags&TH_RST) || 703 tlen == 0 && (tiflags&(TH_SYN|TH_FIN)) == 0) 704 goto drop; 705 if (tp->t_inpcb->inp_socket->so_options & SO_DEBUG) 706 tcp_trace(TA_RESPOND, ostate, tp, &tcp_saveti, 0); 707 tcp_respond(tp, ti, tp->rcv_nxt, tp->snd_nxt, TH_ACK); 708 return; 709 710 dropwithreset: 711 if (om) 712 (void) m_free(om); 713 /* 714 * Generate a RST, dropping incoming segment. 715 * Make ACK acceptable to originator of segment. 716 */ 717 if (tiflags & TH_RST) 718 goto drop; 719 if (tiflags & TH_ACK) 720 tcp_respond(tp, ti, (tcp_seq)0, ti->ti_ack, TH_RST); 721 else { 722 if (tiflags & TH_SYN) 723 ti->ti_len++; 724 tcp_respond(tp, ti, ti->ti_seq+ti->ti_len, (tcp_seq)0, 725 TH_RST|TH_ACK); 726 } 727 return; 728 729 drop: 730 /* 731 * Drop space held by incoming segment and return. 732 */ 733 if (tp && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) 734 tcp_trace(TA_DROP, ostate, tp, &tcp_saveti, 0); 735 m_freem(m); 736 return; 737 } 738 739 tcp_dooptions(tp, om) 740 struct tcpcb *tp; 741 struct mbuf *om; 742 { 743 register u_char *cp; 744 int opt, optlen, cnt; 745 746 cp = mtod(om, u_char *); 747 cnt = om->m_len; 748 for (; cnt > 0; cnt -= optlen, cp += optlen) { 749 opt = cp[0]; 750 if (opt == TCPOPT_EOL) 751 break; 752 if (opt == TCPOPT_NOP) 753 optlen = 1; 754 else 755 optlen = cp[1]; 756 switch (opt) { 757 758 default: 759 break; 760 761 case TCPOPT_MAXSEG: 762 if (optlen != 4) 763 continue; 764 tp->t_maxseg = *(u_short *)(cp + 2); 765 #if vax || pdp11 766 tp->t_maxseg = ntohs((u_short)tp->t_maxseg); 767 #endif 768 break; 769 770 #ifdef TCPTRUEOOB 771 case TCPOPT_WILLOOB: 772 tp->t_flags |= TF_DOOOB; 773 printf("tp %x dooob\n", tp); 774 break; 775 776 case TCPOPT_OOBDATA: { 777 int seq; 778 register struct socket *so = tp->t_inpcb->inp_socket; 779 tcp_seq mark; 780 781 if (optlen != 8) 782 continue; 783 seq = cp[2]; 784 if (seq < tp->t_iobseq) 785 seq += 256; 786 printf("oobdata cp[2] %d iobseq %d seq %d\n", cp[2], tp->t_iobseq, seq); 787 if (seq - tp->t_iobseq > 128) { 788 printf("bad seq\n"); 789 tp->t_oobflags |= TCPOOB_OWEACK; 790 break; 791 } 792 tp->t_iobseq = cp[2]; 793 tp->t_iobc = cp[3]; 794 mark = *(tcp_seq *)(cp + 4); 795 #if vax || pdp11 796 mark = ntohl(mark); 797 #endif 798 so->so_oobmark = so->so_rcv.sb_cc + (mark-tp->rcv_nxt); 799 if (so->so_oobmark == 0) 800 so->so_state |= SS_RCVATMARK; 801 printf("take oob data %x input iobseq now %x\n", tp->t_iobc, tp->t_iobseq); 802 sohasoutofband(so); 803 break; 804 } 805 806 case TCPOPT_OOBACK: { 807 int seq; 808 809 if (optlen != 4) 810 continue; 811 if (tp->t_oobseq != cp[2]) { 812 printf("wrong ack\n"); 813 break; 814 } 815 printf("take oob ack %x and cancel rexmt\n", cp[2]); 816 tp->t_oobflags &= ~TCPOOB_NEEDACK; 817 tp->t_timer[TCPT_OOBREXMT] = 0; 818 break; 819 } 820 #endif TCPTRUEOOB 821 } 822 } 823 (void) m_free(om); 824 } 825 826 /* 827 * Pull out of band byte out of a segment so 828 * it doesn't appear in the user's data queue. 829 * It is still reflected in the segment length for 830 * sequencing purposes. 831 */ 832 tcp_pulloutofband(so, ti) 833 struct socket *so; 834 struct tcpiphdr *ti; 835 { 836 register struct mbuf *m; 837 int cnt = ti->ti_urp - 1; 838 839 m = dtom(ti); 840 while (cnt >= 0) { 841 if (m->m_len > cnt) { 842 char *cp = mtod(m, caddr_t) + cnt; 843 struct tcpcb *tp = sototcpcb(so); 844 845 tp->t_iobc = *cp; 846 tp->t_oobflags |= TCPOOB_HAVEDATA; 847 bcopy(cp+1, cp, (unsigned)(m->m_len - cnt - 1)); 848 m->m_len--; 849 return; 850 } 851 cnt -= m->m_len; 852 m = m->m_next; 853 if (m == 0) 854 break; 855 } 856 panic("tcp_pulloutofband"); 857 } 858 859 /* 860 * Insert segment ti into reassembly queue of tcp with 861 * control block tp. Return TH_FIN if reassembly now includes 862 * a segment with FIN. 863 */ 864 tcp_reass(tp, ti) 865 register struct tcpcb *tp; 866 register struct tcpiphdr *ti; 867 { 868 register struct tcpiphdr *q; 869 struct socket *so = tp->t_inpcb->inp_socket; 870 struct mbuf *m; 871 int flags; 872 873 /* 874 * Call with ti==0 after become established to 875 * force pre-ESTABLISHED data up to user socket. 876 */ 877 if (ti == 0) 878 goto present; 879 880 /* 881 * Find a segment which begins after this one does. 882 */ 883 for (q = tp->seg_next; q != (struct tcpiphdr *)tp; 884 q = (struct tcpiphdr *)q->ti_next) 885 if (SEQ_GT(q->ti_seq, ti->ti_seq)) 886 break; 887 888 /* 889 * If there is a preceding segment, it may provide some of 890 * our data already. If so, drop the data from the incoming 891 * segment. If it provides all of our data, drop us. 892 */ 893 if ((struct tcpiphdr *)q->ti_prev != (struct tcpiphdr *)tp) { 894 register int i; 895 q = (struct tcpiphdr *)q->ti_prev; 896 /* conversion to int (in i) handles seq wraparound */ 897 i = q->ti_seq + q->ti_len - ti->ti_seq; 898 if (i > 0) { 899 if (i >= ti->ti_len) 900 goto drop; 901 m_adj(dtom(ti), i); 902 ti->ti_len -= i; 903 ti->ti_seq += i; 904 } 905 q = (struct tcpiphdr *)(q->ti_next); 906 } 907 908 /* 909 * While we overlap succeeding segments trim them or, 910 * if they are completely covered, dequeue them. 911 */ 912 while (q != (struct tcpiphdr *)tp) { 913 register int i = (ti->ti_seq + ti->ti_len) - q->ti_seq; 914 if (i <= 0) 915 break; 916 if (i < q->ti_len) { 917 q->ti_seq += i; 918 q->ti_len -= i; 919 m_adj(dtom(q), i); 920 break; 921 } 922 q = (struct tcpiphdr *)q->ti_next; 923 m = dtom(q->ti_prev); 924 remque(q->ti_prev); 925 m_freem(m); 926 } 927 928 /* 929 * Stick new segment in its place. 930 */ 931 insque(ti, q->ti_prev); 932 933 present: 934 /* 935 * Present data to user, advancing rcv_nxt through 936 * completed sequence space. 937 */ 938 if (TCPS_HAVERCVDSYN(tp->t_state) == 0) 939 return (0); 940 ti = tp->seg_next; 941 if (ti == (struct tcpiphdr *)tp || ti->ti_seq != tp->rcv_nxt) 942 return (0); 943 if (tp->t_state == TCPS_SYN_RECEIVED && ti->ti_len) 944 return (0); 945 do { 946 tp->rcv_nxt += ti->ti_len; 947 flags = ti->ti_flags & TH_FIN; 948 remque(ti); 949 m = dtom(ti); 950 ti = (struct tcpiphdr *)ti->ti_next; 951 if (so->so_state & SS_CANTRCVMORE) 952 m_freem(m); 953 else 954 sbappend(&so->so_rcv, m); 955 } while (ti != (struct tcpiphdr *)tp && ti->ti_seq == tp->rcv_nxt); 956 sorwakeup(so); 957 return (flags); 958 drop: 959 m_freem(dtom(ti)); 960 return (0); 961 } 962