1 /* tcp_input.c 1.68 82/06/20 */ 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 sockaddr_in tcp_in = { AF_INET }; 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. On match, update the local 137 * address stored in the block to reflect anchoring. 138 */ 139 inp = in_pcblookup 140 (&tcb, ti->ti_src, ti->ti_sport, ti->ti_dst, ti->ti_dport, 141 INPLOOKUP_WILDCARD); 142 143 /* 144 * If the state is CLOSED (i.e., TCB does not exist) then 145 * all data in the incoming segment is discarded. 146 */ 147 if (inp == 0) 148 goto dropwithreset; 149 tp = intotcpcb(inp); 150 if (tp == 0) 151 goto dropwithreset; 152 so = inp->inp_socket; 153 if (so->so_options & SO_DEBUG) { 154 ostate = tp->t_state; 155 tcp_saveti = *ti; 156 } 157 158 /* 159 * Segment received on connection. 160 * Reset idle time and keep-alive timer. 161 */ 162 tp->t_idle = 0; 163 tp->t_timer[TCPT_KEEP] = TCPTV_KEEP; 164 165 /* 166 * Process options. 167 */ 168 if (om) { 169 tcp_dooptions(tp, om); 170 om = 0; 171 } 172 173 /* 174 * Calculate amount of space in receive window, 175 * and then do TCP input processing. 176 */ 177 tp->rcv_wnd = sbspace(&so->so_rcv); 178 if (tp->rcv_wnd < 0) 179 tp->rcv_wnd = 0; 180 181 switch (tp->t_state) { 182 183 /* 184 * If the state is LISTEN then ignore segment if it contains an RST. 185 * If the segment contains an ACK then it is bad and send a RST. 186 * If it does not contain a SYN then it is not interesting; drop it. 187 * Otherwise initialize tp->rcv_nxt, and tp->irs, select an initial 188 * tp->iss, and send a segment: 189 * <SEQ=ISS><ACK=RCV_NXT><CTL=SYN,ACK> 190 * Also initialize tp->snd_nxt to tp->iss+1 and tp->snd_una to tp->iss. 191 * Fill in remote peer address fields if not previously specified. 192 * Enter SYN_RECEIVED state, and process any other fields of this 193 * segment in this state. 194 */ 195 case TCPS_LISTEN: 196 if (tiflags & TH_RST) 197 goto drop; 198 if (tiflags & TH_ACK) 199 goto dropwithreset; 200 if ((tiflags & TH_SYN) == 0) 201 goto drop; 202 tcp_in.sin_addr = ti->ti_src; 203 tcp_in.sin_port = ti->ti_sport; 204 laddr = inp->inp_laddr; 205 if (inp->inp_laddr.s_addr == 0) 206 inp->inp_laddr = ti->ti_dst; 207 if (in_pcbconnect(inp, (struct sockaddr_in *)&tcp_in)) { 208 inp->inp_laddr = laddr; 209 goto drop; 210 } 211 tp->t_template = tcp_template(tp); 212 if (tp->t_template == 0) { 213 in_pcbdisconnect(inp); 214 inp->inp_laddr = laddr; 215 tp = 0; 216 goto drop; 217 } 218 tp->iss = tcp_iss; tcp_iss += TCP_ISSINCR/2; 219 tp->irs = ti->ti_seq; 220 tcp_sendseqinit(tp); 221 tcp_rcvseqinit(tp); 222 tp->t_state = TCPS_SYN_RECEIVED; 223 tp->t_timer[TCPT_KEEP] = TCPTV_KEEP; 224 goto trimthenstep6; 225 226 /* 227 * If the state is SYN_SENT: 228 * if seg contains an ACK, but not for our SYN, drop the input. 229 * if seg contains a RST, then drop the connection. 230 * if seg does not contain SYN, then drop it. 231 * Otherwise this is an acceptable SYN segment 232 * initialize tp->rcv_nxt and tp->irs 233 * if seg contains ack then advance tp->snd_una 234 * if SYN has been acked change to ESTABLISHED else SYN_RCVD state 235 * arrange for segment to be acked (eventually) 236 * continue processing rest of data/controls, beginning with URG 237 */ 238 case TCPS_SYN_SENT: 239 if ((tiflags & TH_ACK) && 240 /* this should be SEQ_LT; is SEQ_LEQ for BBN vax TCP only */ 241 (SEQ_LT(ti->ti_ack, tp->iss) || 242 SEQ_GT(ti->ti_ack, tp->snd_max))) 243 goto dropwithreset; 244 if (tiflags & TH_RST) { 245 if (tiflags & TH_ACK) { 246 tcp_drop(tp, ECONNREFUSED); 247 tp = 0; 248 } 249 goto drop; 250 } 251 if ((tiflags & TH_SYN) == 0) 252 goto drop; 253 tp->snd_una = ti->ti_ack; 254 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 255 tp->snd_nxt = tp->snd_una; 256 tp->t_timer[TCPT_REXMT] = 0; 257 tp->irs = ti->ti_seq; 258 tcp_rcvseqinit(tp); 259 tp->t_flags |= TF_ACKNOW; 260 if (SEQ_GT(tp->snd_una, tp->iss)) { 261 if (so->so_options & SO_ACCEPTCONN) 262 so->so_state |= SS_CONNAWAITING; 263 soisconnected(so); 264 tp->t_state = TCPS_ESTABLISHED; 265 (void) tcp_reass(tp, (struct tcpiphdr *)0); 266 } else 267 tp->t_state = TCPS_SYN_RECEIVED; 268 goto trimthenstep6; 269 270 trimthenstep6: 271 /* 272 * Advance ti->ti_seq to correspond to first data byte. 273 * If data, trim to stay within window, 274 * dropping FIN if necessary. 275 */ 276 ti->ti_seq++; 277 if (ti->ti_len > tp->rcv_wnd) { 278 todrop = ti->ti_len - tp->rcv_wnd; 279 m_adj(m, -todrop); 280 ti->ti_len = tp->rcv_wnd; 281 ti->ti_flags &= ~TH_FIN; 282 } 283 tp->snd_wl1 = ti->ti_seq - 1; 284 goto step6; 285 } 286 287 /* 288 * States other than LISTEN or SYN_SENT. 289 * First check that at least some bytes of segment are within 290 * receive window. 291 */ 292 if (tp->rcv_wnd == 0) { 293 /* 294 * If window is closed can only take segments at 295 * window edge, and have to drop data and PUSH from 296 * incoming segments. 297 */ 298 if (tp->rcv_nxt != ti->ti_seq) 299 goto dropafterack; 300 if (ti->ti_len > 0) { 301 m_adj(m, ti->ti_len); 302 ti->ti_len = 0; 303 ti->ti_flags &= ~(TH_PUSH|TH_FIN); 304 } 305 } else { 306 /* 307 * If segment begins before rcv_nxt, drop leading 308 * data (and SYN); if nothing left, just ack. 309 */ 310 todrop = tp->rcv_nxt - ti->ti_seq; 311 if (todrop > 0) { 312 if (tiflags & TH_SYN) { 313 tiflags &= ~TH_SYN; 314 ti->ti_flags &= ~TH_SYN; 315 ti->ti_seq++; 316 if (ti->ti_urp > 1) 317 ti->ti_urp--; 318 else 319 tiflags &= ~TH_URG; 320 todrop--; 321 } 322 if (todrop > ti->ti_len || 323 todrop == ti->ti_len && (tiflags&TH_FIN) == 0) 324 goto dropafterack; 325 m_adj(m, todrop); 326 ti->ti_seq += todrop; 327 ti->ti_len -= todrop; 328 if (ti->ti_urp > todrop) 329 ti->ti_urp -= todrop; 330 else { 331 tiflags &= ~TH_URG; 332 ti->ti_flags &= ~TH_URG; 333 ti->ti_urp = 0; 334 } 335 } 336 /* 337 * If segment ends after window, drop trailing data 338 * (and PUSH and FIN); if nothing left, just ACK. 339 */ 340 todrop = (ti->ti_seq+ti->ti_len) - (tp->rcv_nxt+tp->rcv_wnd); 341 if (todrop > 0) { 342 if (todrop >= ti->ti_len) 343 goto dropafterack; 344 m_adj(m, -todrop); 345 ti->ti_len -= todrop; 346 ti->ti_flags &= ~(TH_PUSH|TH_FIN); 347 } 348 } 349 350 /* 351 * If a segment is received on a connection after the 352 * user processes are gone, then RST the other end. 353 */ 354 if (so->so_state & SS_USERGONE) { 355 tcp_close(tp); 356 tp = 0; 357 goto dropwithreset; 358 } 359 360 /* 361 * If the RST bit is set examine the state: 362 * SYN_RECEIVED STATE: 363 * If passive open, return to LISTEN state. 364 * If active open, inform user that connection was refused. 365 * ESTABLISHED, FIN_WAIT_1, FIN_WAIT2, CLOSE_WAIT STATES: 366 * Inform user that connection was reset, and close tcb. 367 * CLOSING, LAST_ACK, TIME_WAIT STATES 368 * Close the tcb. 369 */ 370 if (tiflags&TH_RST) switch (tp->t_state) { 371 372 case TCPS_SYN_RECEIVED: 373 if (inp->inp_socket->so_options & SO_ACCEPTCONN) { 374 /* a miniature tcp_close, but invisible to user */ 375 (void) m_free(dtom(tp->t_template)); 376 (void) m_free(dtom(tp)); 377 inp->inp_ppcb = 0; 378 tp = tcp_newtcpcb(inp); 379 tp->t_state = TCPS_LISTEN; 380 inp->inp_faddr.s_addr = 0; 381 inp->inp_fport = 0; 382 inp->inp_laddr.s_addr = 0; /* not quite right */ 383 tp = 0; 384 goto drop; 385 } 386 tcp_drop(tp, ECONNREFUSED); 387 tp = 0; 388 goto drop; 389 390 case TCPS_ESTABLISHED: 391 case TCPS_FIN_WAIT_1: 392 case TCPS_FIN_WAIT_2: 393 case TCPS_CLOSE_WAIT: 394 tcp_drop(tp, ECONNRESET); 395 tp = 0; 396 goto drop; 397 398 case TCPS_CLOSING: 399 case TCPS_LAST_ACK: 400 case TCPS_TIME_WAIT: 401 tcp_close(tp); 402 tp = 0; 403 goto drop; 404 } 405 406 /* 407 * If a SYN is in the window, then this is an 408 * error and we send an RST and drop the connection. 409 */ 410 if (tiflags & TH_SYN) { 411 tcp_drop(tp, ECONNRESET); 412 tp = 0; 413 goto dropwithreset; 414 } 415 416 /* 417 * If the ACK bit is off we drop the segment and return. 418 */ 419 if ((tiflags & TH_ACK) == 0) 420 goto drop; 421 422 /* 423 * Ack processing. 424 */ 425 switch (tp->t_state) { 426 427 /* 428 * In SYN_RECEIVED state if the ack ACKs our SYN then enter 429 * ESTABLISHED state and continue processing, othewise 430 * send an RST. 431 */ 432 case TCPS_SYN_RECEIVED: 433 if (SEQ_GT(tp->snd_una, ti->ti_ack) || 434 SEQ_GT(ti->ti_ack, tp->snd_max)) 435 goto dropwithreset; 436 tp->snd_una++; /* SYN acked */ 437 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 438 tp->snd_nxt = tp->snd_una; 439 tp->t_timer[TCPT_REXMT] = 0; 440 if (so->so_options & SO_ACCEPTCONN) 441 so->so_state |= SS_CONNAWAITING; 442 soisconnected(so); 443 tp->t_state = TCPS_ESTABLISHED; 444 (void) tcp_reass(tp, (struct tcpiphdr *)0); 445 tp->snd_wl1 = ti->ti_seq - 1; 446 /* fall into ... */ 447 448 /* 449 * In ESTABLISHED state: drop duplicate ACKs; ACK out of range 450 * ACKs. If the ack is in the range 451 * tp->snd_una < ti->ti_ack <= tp->snd_max 452 * then advance tp->snd_una to ti->ti_ack and drop 453 * data from the retransmission queue. If this ACK reflects 454 * more up to date window information we update our window information. 455 */ 456 case TCPS_ESTABLISHED: 457 case TCPS_FIN_WAIT_1: 458 case TCPS_FIN_WAIT_2: 459 case TCPS_CLOSE_WAIT: 460 case TCPS_CLOSING: 461 case TCPS_LAST_ACK: 462 case TCPS_TIME_WAIT: 463 #define ourfinisacked (acked > 0) 464 465 if (SEQ_LEQ(ti->ti_ack, tp->snd_una)) 466 break; 467 if (SEQ_GT(ti->ti_ack, tp->snd_max)) 468 goto dropafterack; 469 acked = ti->ti_ack - tp->snd_una; 470 471 /* 472 * If transmit timer is running and timed sequence 473 * number was acked, update smoothed round trip time. 474 */ 475 if (tp->t_rtt && SEQ_GT(ti->ti_ack, tp->t_rtseq)) { 476 if (tp->t_srtt == 0) 477 tp->t_srtt = tp->t_rtt; 478 else 479 tp->t_srtt = 480 tcp_alpha * tp->t_srtt + 481 (1 - tcp_alpha) * tp->t_rtt; 482 /* printf("rtt %d srtt*100 now %d\n", tp->t_rtt, (int)(tp->t_srtt*100)); */ 483 tp->t_rtt = 0; 484 } 485 486 if (ti->ti_ack == tp->snd_max) 487 tp->t_timer[TCPT_REXMT] = 0; 488 else { 489 TCPT_RANGESET(tp->t_timer[TCPT_REXMT], 490 tcp_beta * tp->t_srtt, TCPTV_MIN, TCPTV_MAX); 491 tp->t_rtt = 1; 492 tp->t_rxtshift = 0; 493 } 494 if (acked > so->so_snd.sb_cc) { 495 sbdrop(&so->so_snd, so->so_snd.sb_cc); 496 tp->snd_wnd -= so->so_snd.sb_cc; 497 } else { 498 sbdrop(&so->so_snd, acked); 499 tp->snd_wnd -= acked; 500 acked = 0; 501 } 502 if ((so->so_snd.sb_flags & SB_WAIT) || so->so_snd.sb_sel) 503 sowwakeup(so); 504 tp->snd_una = ti->ti_ack; 505 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 506 tp->snd_nxt = tp->snd_una; 507 508 switch (tp->t_state) { 509 510 /* 511 * In FIN_WAIT_1 STATE in addition to the processing 512 * for the ESTABLISHED state if our FIN is now acknowledged 513 * then enter FIN_WAIT_2. 514 */ 515 case TCPS_FIN_WAIT_1: 516 if (ourfinisacked) { 517 /* 518 * If we can't receive any more 519 * data, then closing user can proceed. 520 */ 521 if (so->so_state & SS_CANTRCVMORE) 522 soisdisconnected(so); 523 tp->t_state = TCPS_FIN_WAIT_2; 524 } 525 break; 526 527 /* 528 * In CLOSING STATE in addition to the processing for 529 * the ESTABLISHED state if the ACK acknowledges our FIN 530 * then enter the TIME-WAIT state, otherwise ignore 531 * the segment. 532 */ 533 case TCPS_CLOSING: 534 if (ourfinisacked) { 535 tp->t_state = TCPS_TIME_WAIT; 536 tcp_canceltimers(tp); 537 tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; 538 soisdisconnected(so); 539 } 540 break; 541 542 /* 543 * The only thing that can arrive in LAST_ACK state 544 * is an acknowledgment of our FIN. If our FIN is now 545 * acknowledged, delete the TCB, enter the closed state 546 * and return. 547 */ 548 case TCPS_LAST_ACK: 549 if (ourfinisacked) { 550 tcp_close(tp); 551 tp = 0; 552 } 553 goto drop; 554 555 /* 556 * In TIME_WAIT state the only thing that should arrive 557 * is a retransmission of the remote FIN. Acknowledge 558 * it and restart the finack timer. 559 */ 560 case TCPS_TIME_WAIT: 561 tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; 562 goto dropafterack; 563 } 564 #undef ourfinisacked 565 } 566 567 step6: 568 /* 569 * Update window information. 570 */ 571 if (SEQ_LT(tp->snd_wl1, ti->ti_seq) || tp->snd_wl1 == ti->ti_seq && 572 (SEQ_LT(tp->snd_wl2, ti->ti_ack) || 573 tp->snd_wl2 == ti->ti_ack && ti->ti_win > tp->snd_wnd)) { 574 tp->snd_wnd = ti->ti_win; 575 tp->snd_wl1 = ti->ti_seq; 576 tp->snd_wl2 = ti->ti_ack; 577 if (tp->snd_wnd > 0) 578 tp->t_timer[TCPT_PERSIST] = 0; 579 } 580 581 /* 582 * Process segments with URG. 583 */ 584 if ((tiflags & TH_URG) && TCPS_HAVERCVDFIN(tp->t_state) == 0) { 585 /* 586 * If this segment advances the known urgent pointer, 587 * then mark the data stream. This should not happen 588 * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since 589 * a FIN has been received from the remote side. 590 * In these states we ignore the URG. 591 */ 592 if (SEQ_GT(ti->ti_seq+ti->ti_urp, tp->rcv_up)) { 593 tp->rcv_up = ti->ti_seq + ti->ti_urp; 594 so->so_oobmark = so->so_rcv.sb_cc + 595 (tp->rcv_up - tp->rcv_nxt) - 1; 596 if (so->so_oobmark == 0) 597 so->so_state |= SS_RCVATMARK; 598 #ifdef TCPTRUEOOB 599 if ((tp->t_flags & TF_DOOOB) == 0) 600 #endif 601 sohasoutofband(so); 602 tp->t_oobflags &= ~TCPOOB_HAVEDATA; 603 } 604 /* 605 * Remove out of band data so doesn't get presented to user. 606 * This can happen independent of advancing the URG pointer, 607 * but if two URG's are pending at once, some out-of-band 608 * data may creep in... ick. 609 */ 610 if (ti->ti_urp <= ti->ti_len) { 611 tcp_pulloutofband(so, ti); 612 } 613 } 614 615 /* 616 * Process the segment text, merging it into the TCP sequencing queue, 617 * and arranging for acknowledgment of receipt if necessary. 618 * This process logically involves adjusting tp->rcv_wnd as data 619 * is presented to the user (this happens in tcp_usrreq.c, 620 * case PRU_RCVD). If a FIN has already been received on this 621 * connection then we just ignore the text. 622 */ 623 if ((ti->ti_len || (tiflags&TH_FIN)) && 624 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 625 tiflags = tcp_reass(tp, ti); 626 if (tcpnodelack == 0) 627 tp->t_flags |= TF_DELACK; 628 else 629 tp->t_flags |= TF_ACKNOW; 630 } else { 631 m_freem(m); 632 tiflags &= ~TH_FIN; 633 } 634 635 /* 636 * If FIN is received ACK the FIN and let the user know 637 * that the connection is closing. 638 */ 639 if (tiflags & TH_FIN) { 640 if (TCPS_HAVERCVDFIN(tp->t_state) == 0) { 641 socantrcvmore(so); 642 tp->t_flags |= TF_ACKNOW; 643 tp->rcv_nxt++; 644 } 645 switch (tp->t_state) { 646 647 /* 648 * In SYN_RECEIVED and ESTABLISHED STATES 649 * enter the CLOSE_WAIT state. 650 */ 651 case TCPS_SYN_RECEIVED: 652 case TCPS_ESTABLISHED: 653 tp->t_state = TCPS_CLOSE_WAIT; 654 break; 655 656 /* 657 * If still in FIN_WAIT_1 STATE FIN has not been acked so 658 * enter the CLOSING state. 659 */ 660 case TCPS_FIN_WAIT_1: 661 tp->t_state = TCPS_CLOSING; 662 break; 663 664 /* 665 * In FIN_WAIT_2 state enter the TIME_WAIT state, 666 * starting the time-wait timer, turning off the other 667 * standard timers. 668 */ 669 case TCPS_FIN_WAIT_2: 670 tp->t_state = TCPS_TIME_WAIT; 671 tcp_canceltimers(tp); 672 tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; 673 soisdisconnected(so); 674 break; 675 676 /* 677 * In TIME_WAIT state restart the 2 MSL time_wait timer. 678 */ 679 case TCPS_TIME_WAIT: 680 tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; 681 break; 682 } 683 } 684 if (so->so_options & SO_DEBUG) 685 tcp_trace(TA_INPUT, ostate, tp, &tcp_saveti, 0); 686 687 /* 688 * Return any desired output. 689 */ 690 (void) tcp_output(tp); 691 return; 692 693 dropafterack: 694 /* 695 * Generate an ACK dropping incoming segment if it occupies 696 * sequence space, where the ACK reflects our state. 697 */ 698 if ((tiflags&TH_RST) || 699 tlen == 0 && (tiflags&(TH_SYN|TH_FIN)) == 0) 700 goto drop; 701 if (tp->t_inpcb->inp_socket->so_options & SO_DEBUG) 702 tcp_trace(TA_RESPOND, ostate, tp, &tcp_saveti, 0); 703 tcp_respond(tp, ti, tp->rcv_nxt, tp->snd_nxt, TH_ACK); 704 return; 705 706 dropwithreset: 707 if (om) 708 (void) m_free(om); 709 /* 710 * Generate a RST, dropping incoming segment. 711 * Make ACK acceptable to originator of segment. 712 */ 713 if (tiflags & TH_RST) 714 goto drop; 715 if (tiflags & TH_ACK) 716 tcp_respond(tp, ti, (tcp_seq)0, ti->ti_ack, TH_RST); 717 else { 718 if (tiflags & TH_SYN) 719 ti->ti_len++; 720 tcp_respond(tp, ti, ti->ti_seq+ti->ti_len, (tcp_seq)0, 721 TH_RST|TH_ACK); 722 } 723 return; 724 725 drop: 726 /* 727 * Drop space held by incoming segment and return. 728 */ 729 if (tp && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) 730 tcp_trace(TA_DROP, ostate, tp, &tcp_saveti, 0); 731 m_freem(m); 732 return; 733 } 734 735 tcp_dooptions(tp, om) 736 struct tcpcb *tp; 737 struct mbuf *om; 738 { 739 register u_char *cp; 740 int opt, optlen, cnt; 741 742 cp = mtod(om, u_char *); 743 cnt = om->m_len; 744 for (; cnt > 0; cnt -= optlen, cp += optlen) { 745 opt = cp[0]; 746 if (opt == TCPOPT_EOL) 747 break; 748 if (opt == TCPOPT_NOP) 749 optlen = 1; 750 else 751 optlen = cp[1]; 752 switch (opt) { 753 754 default: 755 break; 756 757 case TCPOPT_MAXSEG: 758 if (optlen != 4) 759 continue; 760 tp->t_maxseg = *(u_short *)(cp + 2); 761 #if vax || pdp11 762 tp->t_maxseg = ntohs((u_short)tp->t_maxseg); 763 #endif 764 break; 765 766 #ifdef TCPTRUEOOB 767 case TCPOPT_WILLOOB: 768 tp->t_flags |= TF_DOOOB; 769 printf("tp %x dooob\n", tp); 770 break; 771 772 case TCPOPT_OOBDATA: { 773 int seq; 774 register struct socket *so = tp->t_inpcb->inp_socket; 775 tcp_seq mark; 776 777 if (optlen != 8) 778 continue; 779 seq = cp[2]; 780 if (seq < tp->t_iobseq) 781 seq += 256; 782 printf("oobdata cp[2] %d iobseq %d seq %d\n", cp[2], tp->t_iobseq, seq); 783 if (seq - tp->t_iobseq > 128) { 784 printf("bad seq\n"); 785 tp->t_oobflags |= TCPOOB_OWEACK; 786 break; 787 } 788 tp->t_iobseq = cp[2]; 789 tp->t_iobc = cp[3]; 790 mark = *(tcp_seq *)(cp + 4); 791 #if vax || pdp11 792 mark = ntohl(mark); 793 #endif 794 so->so_oobmark = so->so_rcv.sb_cc + (mark-tp->rcv_nxt); 795 if (so->so_oobmark == 0) 796 so->so_state |= SS_RCVATMARK; 797 printf("take oob data %x input iobseq now %x\n", tp->t_iobc, tp->t_iobseq); 798 sohasoutofband(so); 799 break; 800 } 801 802 case TCPOPT_OOBACK: { 803 int seq; 804 805 if (optlen != 4) 806 continue; 807 if (tp->t_oobseq != cp[2]) { 808 printf("wrong ack\n"); 809 break; 810 } 811 printf("take oob ack %x and cancel rexmt\n", cp[2]); 812 tp->t_oobflags &= ~TCPOOB_NEEDACK; 813 tp->t_timer[TCPT_OOBREXMT] = 0; 814 break; 815 } 816 #endif TCPTRUEOOB 817 } 818 } 819 (void) m_free(om); 820 } 821 822 /* 823 * Pull out of band byte out of a segment so 824 * it doesn't appear in the user's data queue. 825 * It is still reflected in the segment length for 826 * sequencing purposes. 827 */ 828 tcp_pulloutofband(so, ti) 829 struct socket *so; 830 struct tcpiphdr *ti; 831 { 832 register struct mbuf *m; 833 int cnt = ti->ti_urp - 1; 834 835 m = dtom(ti); 836 while (cnt >= 0) { 837 if (m->m_len > cnt) { 838 char *cp = mtod(m, caddr_t) + cnt; 839 struct tcpcb *tp = sototcpcb(so); 840 841 tp->t_iobc = *cp; 842 tp->t_oobflags |= TCPOOB_HAVEDATA; 843 bcopy(cp+1, cp, (unsigned)(m->m_len - cnt - 1)); 844 m->m_len--; 845 return; 846 } 847 cnt -= m->m_len; 848 m = m->m_next; 849 if (m == 0) 850 break; 851 } 852 panic("tcp_pulloutofband"); 853 } 854 855 /* 856 * Insert segment ti into reassembly queue of tcp with 857 * control block tp. Return TH_FIN if reassembly now includes 858 * a segment with FIN. 859 */ 860 tcp_reass(tp, ti) 861 register struct tcpcb *tp; 862 register struct tcpiphdr *ti; 863 { 864 register struct tcpiphdr *q; 865 struct socket *so = tp->t_inpcb->inp_socket; 866 struct mbuf *m; 867 int flags; 868 869 /* 870 * Call with ti==0 after become established to 871 * force pre-ESTABLISHED data up to user socket. 872 */ 873 if (ti == 0) 874 goto present; 875 876 /* 877 * Find a segment which begins after this one does. 878 */ 879 for (q = tp->seg_next; q != (struct tcpiphdr *)tp; 880 q = (struct tcpiphdr *)q->ti_next) 881 if (SEQ_GT(q->ti_seq, ti->ti_seq)) 882 break; 883 884 /* 885 * If there is a preceding segment, it may provide some of 886 * our data already. If so, drop the data from the incoming 887 * segment. If it provides all of our data, drop us. 888 */ 889 if ((struct tcpiphdr *)q->ti_prev != (struct tcpiphdr *)tp) { 890 register int i; 891 q = (struct tcpiphdr *)q->ti_prev; 892 /* conversion to int (in i) handles seq wraparound */ 893 i = q->ti_seq + q->ti_len - ti->ti_seq; 894 if (i > 0) { 895 if (i >= ti->ti_len) 896 goto drop; 897 m_adj(dtom(tp), i); 898 ti->ti_len -= i; 899 ti->ti_seq += i; 900 } 901 q = (struct tcpiphdr *)(q->ti_next); 902 } 903 904 /* 905 * While we overlap succeeding segments trim them or, 906 * if they are completely covered, dequeue them. 907 */ 908 while (q != (struct tcpiphdr *)tp) { 909 register int i = (ti->ti_seq + ti->ti_len) - q->ti_seq; 910 if (i <= 0) 911 break; 912 if (i < q->ti_len) { 913 q->ti_seq += i; 914 q->ti_len -= i; 915 m_adj(dtom(q), i); 916 break; 917 } 918 q = (struct tcpiphdr *)q->ti_next; 919 m = dtom(q->ti_prev); 920 remque(q->ti_prev); 921 m_freem(m); 922 } 923 924 /* 925 * Stick new segment in its place. 926 */ 927 insque(ti, q->ti_prev); 928 929 present: 930 /* 931 * Present data to user, advancing rcv_nxt through 932 * completed sequence space. 933 */ 934 if (TCPS_HAVERCVDSYN(tp->t_state) == 0) 935 return (0); 936 ti = tp->seg_next; 937 if (ti == (struct tcpiphdr *)tp || ti->ti_seq != tp->rcv_nxt) 938 return (0); 939 if (tp->t_state == TCPS_SYN_RECEIVED && ti->ti_len) 940 return (0); 941 do { 942 tp->rcv_nxt += ti->ti_len; 943 flags = ti->ti_flags & TH_FIN; 944 remque(ti); 945 m = dtom(ti); 946 ti = (struct tcpiphdr *)ti->ti_next; 947 if (so->so_state & SS_CANTRCVMORE) 948 m_freem(m); 949 else 950 sbappend(&so->so_rcv, m); 951 } while (ti != (struct tcpiphdr *)tp && ti->ti_seq == tp->rcv_nxt); 952 sorwakeup(so); 953 return (flags); 954 drop: 955 m_freem(dtom(ti)); 956 return (0); 957 } 958