1 /* tcp_input.c 1.59 82/03/11 */ 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/in_pcb.h" 11 #include "../net/in_systm.h" 12 #include "../net/if.h" 13 #include "../net/ip.h" 14 #include "../net/ip_var.h" 15 #include "../net/tcp.h" 16 #include "../net/tcp_fsm.h" 17 #include "../net/tcp_seq.h" 18 #include "../net/tcp_timer.h" 19 #include "../net/tcp_var.h" 20 #include "../net/tcpip.h" 21 #include "../net/tcp_debug.h" 22 #include "../errno.h" 23 24 int tcpprintfs = 0; 25 int tcpcksum = 1; 26 struct sockaddr_in tcp_in = { AF_INET }; 27 struct tcpiphdr tcp_saveti; 28 extern tcpnodelack; 29 30 struct tcpcb *tcp_newtcpcb(); 31 /* 32 * TCP input routine, follows pages 65-76 of the 33 * protocol specification dated September, 1981 very closely. 34 */ 35 tcp_input(m0) 36 struct mbuf *m0; 37 { 38 register struct tcpiphdr *ti; 39 struct inpcb *inp; 40 register struct mbuf *m; 41 struct mbuf *om = 0; 42 int len, tlen, off; 43 register struct tcpcb *tp = 0; 44 register int tiflags; 45 struct socket *so; 46 int todrop, acked; 47 short ostate; 48 struct in_addr laddr; 49 50 COUNT(TCP_INPUT); 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 77 ti->ti_len = htons(ti->ti_len); 78 #endif 79 if (ti->ti_sum = in_cksum(m, len)) { 80 tcpstat.tcps_badsum++; 81 printf("tcp cksum %x\n", ti->ti_sum); 82 goto drop; 83 } 84 } 85 86 /* 87 * Check that TCP offset makes sense, 88 * pull out TCP options and adjust length. 89 */ 90 off = ti->ti_off << 2; 91 if (off < sizeof (struct tcphdr) || off > tlen) { 92 tcpstat.tcps_badoff++; 93 goto drop; 94 } 95 ti->ti_len = tlen - off; 96 if (off > sizeof (struct tcphdr)) { 97 if ((m = m_pullup(m, sizeof (struct ip) + off)) == 0) { 98 tcpstat.tcps_hdrops++; 99 goto drop; 100 } 101 ti = mtod(m, struct tcpiphdr *); 102 om = m_get(M_DONTWAIT); 103 if (om == 0) 104 goto drop; 105 om->m_off = MMINOFF; 106 om->m_len = off - sizeof (struct tcphdr); 107 { caddr_t op = mtod(m, caddr_t) + sizeof (struct tcpiphdr); 108 bcopy(op, mtod(om, caddr_t), om->m_len); 109 m->m_len -= om->m_len; 110 bcopy(op+om->m_len, op, m->m_len-sizeof (struct tcpiphdr)); 111 } 112 } 113 tiflags = ti->ti_flags; 114 115 /* 116 * drop IP header 117 */ 118 off += sizeof (struct ip); 119 m->m_off += off; 120 m->m_len -= off; 121 122 #if vax 123 /* 124 * Convert TCP protocol specific fields to host format. 125 */ 126 ti->ti_seq = ntohl(ti->ti_seq); 127 ti->ti_ack = ntohl(ti->ti_ack); 128 ti->ti_win = ntohs(ti->ti_win); 129 ti->ti_urp = ntohs(ti->ti_urp); 130 #endif 131 132 /* 133 * Locate pcb for segment. On match, update the local 134 * address stored in the block to reflect anchoring. 135 */ 136 inp = in_pcblookup 137 (&tcb, ti->ti_src, ti->ti_sport, ti->ti_dst, ti->ti_dport, 138 INPLOOKUP_WILDCARD); 139 140 /* 141 * If the state is CLOSED (i.e., TCB does not exist) then 142 * all data in the incoming segment is discarded. 143 */ 144 if (inp == 0) 145 goto dropwithreset; 146 tp = intotcpcb(inp); 147 if (tp == 0) 148 goto dropwithreset; 149 so = inp->inp_socket; 150 if (so->so_options & SO_DEBUG) { 151 ostate = tp->t_state; 152 tcp_saveti = *ti; 153 } 154 155 /* 156 * Segment received on connection. 157 * Reset idle time and keep-alive timer. 158 */ 159 tp->t_idle = 0; 160 tp->t_timer[TCPT_KEEP] = TCPTV_KEEP; 161 162 /* 163 * Process options. 164 */ 165 if (om) { 166 tcp_dooptions(tp, om); 167 om = 0; 168 } 169 170 /* 171 * Calculate amount of space in receive window, 172 * and then do TCP input processing. 173 */ 174 tp->rcv_wnd = sbspace(&so->so_rcv); 175 if (tp->rcv_wnd < 0) 176 tp->rcv_wnd = 0; 177 178 switch (tp->t_state) { 179 180 /* 181 * If the state is LISTEN then ignore segment if it contains an RST. 182 * If the segment contains an ACK then it is bad and send a RST. 183 * If it does not contain a SYN then it is not interesting; drop it. 184 * Otherwise initialize tp->rcv_nxt, and tp->irs, select an initial 185 * tp->iss, and send a segment: 186 * <SEQ=ISS><ACK=RCV_NXT><CTL=SYN,ACK> 187 * Also initialize tp->snd_nxt to tp->iss+1 and tp->snd_una to tp->iss. 188 * Fill in remote peer address fields if not previously specified. 189 * Enter SYN_RECEIVED state, and process any other fields of this 190 * segment in this state. 191 */ 192 case TCPS_LISTEN: 193 if (tiflags & TH_RST) 194 goto drop; 195 if (tiflags & TH_ACK) 196 goto dropwithreset; 197 if ((tiflags & TH_SYN) == 0) 198 goto drop; 199 tcp_in.sin_addr = ti->ti_src; 200 tcp_in.sin_port = ti->ti_sport; 201 laddr = inp->inp_laddr; 202 if (inp->inp_laddr.s_addr == 0) 203 inp->inp_laddr = ti->ti_dst; 204 if (in_pcbconnect(inp, (struct sockaddr *)&tcp_in)) { 205 inp->inp_laddr = laddr; 206 goto drop; 207 } 208 tp->t_template = tcp_template(tp); 209 if (tp->t_template == 0) { 210 in_pcbdisconnect(inp); 211 inp->inp_laddr = laddr; 212 goto drop; 213 } 214 in_setsockaddr(inp); 215 tp->iss = tcp_iss; tcp_iss += TCP_ISSINCR/2; 216 tp->irs = ti->ti_seq; 217 tcp_sendseqinit(tp); 218 tcp_rcvseqinit(tp); 219 tp->t_state = TCPS_SYN_RECEIVED; 220 tp->t_timer[TCPT_KEEP] = TCPTV_KEEP; 221 goto trimthenstep6; 222 223 /* 224 * If the state is SYN_SENT: 225 * if seg contains an ACK, but not for our SYN, drop the input. 226 * if seg contains a RST, then drop the connection. 227 * if seg does not contain SYN, then drop it. 228 * Otherwise this is an acceptable SYN segment 229 * initialize tp->rcv_nxt and tp->irs 230 * if seg contains ack then advance tp->snd_una 231 * if SYN has been acked change to ESTABLISHED else SYN_RCVD state 232 * arrange for segment to be acked (eventually) 233 * continue processing rest of data/controls, beginning with URG 234 */ 235 case TCPS_SYN_SENT: 236 if ((tiflags & TH_ACK) && 237 /* this should be SEQ_LT; is SEQ_LEQ for BBN vax TCP only */ 238 (SEQ_LT(ti->ti_ack, tp->iss) || 239 SEQ_GT(ti->ti_ack, tp->snd_max))) 240 goto dropwithreset; 241 if (tiflags & TH_RST) { 242 if (tiflags & TH_ACK) 243 tcp_drop(tp, ECONNREFUSED); 244 goto drop; 245 } 246 if ((tiflags & TH_SYN) == 0) 247 goto drop; 248 tp->snd_una = ti->ti_ack; 249 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 250 tp->snd_nxt = tp->snd_una; 251 tp->t_timer[TCPT_REXMT] = 0; 252 tp->irs = ti->ti_seq; 253 tcp_rcvseqinit(tp); 254 tp->t_flags |= TF_ACKNOW; 255 if (SEQ_GT(tp->snd_una, tp->iss)) { 256 if (so->so_options & SO_ACCEPTCONN) 257 so->so_state |= SS_CONNAWAITING; 258 soisconnected(so); 259 tp->t_state = TCPS_ESTABLISHED; 260 (void) tcp_reass(tp, (struct tcpiphdr *)0); 261 } else 262 tp->t_state = TCPS_SYN_RECEIVED; 263 goto trimthenstep6; 264 265 trimthenstep6: 266 /* 267 * Advance ti->ti_seq to correspond to first data byte. 268 * If data, trim to stay within window, 269 * dropping FIN if necessary. 270 */ 271 ti->ti_seq++; 272 if (ti->ti_len > tp->rcv_wnd) { 273 todrop = ti->ti_len - tp->rcv_wnd; 274 m_adj(m, -todrop); 275 ti->ti_len = tp->rcv_wnd; 276 ti->ti_flags &= ~TH_FIN; 277 } 278 tp->snd_wl1 = ti->ti_seq - 1; 279 goto step6; 280 } 281 282 /* 283 * States other than LISTEN or SYN_SENT. 284 * First check that at least some bytes of segment are within 285 * receive window. 286 */ 287 if (tp->rcv_wnd == 0) { 288 /* 289 * If window is closed can only take segments at 290 * window edge, and have to drop data and PUSH from 291 * incoming segments. 292 */ 293 if (tp->rcv_nxt != ti->ti_seq) 294 goto dropafterack; 295 if (ti->ti_len > 0) { 296 m_adj(m, ti->ti_len); 297 ti->ti_len = 0; 298 ti->ti_flags &= ~(TH_PUSH|TH_FIN); 299 } 300 } else { 301 /* 302 * If segment begins before rcv_nxt, drop leading 303 * data (and SYN); if nothing left, just ack. 304 */ 305 todrop = tp->rcv_nxt - ti->ti_seq; 306 if (todrop > 0) { 307 if (tiflags & TH_SYN) { 308 tiflags &= ~TH_SYN; 309 ti->ti_flags &= ~TH_SYN; 310 ti->ti_seq++; 311 if (ti->ti_urp > 1) 312 ti->ti_urp--; 313 else 314 tiflags &= ~TH_URG; 315 todrop--; 316 } 317 if (todrop > ti->ti_len) 318 goto dropafterack; 319 m_adj(m, todrop); 320 ti->ti_seq += todrop; 321 ti->ti_len -= todrop; 322 if (ti->ti_urp > todrop) 323 ti->ti_urp -= todrop; 324 else { 325 tiflags &= ~TH_URG; 326 ti->ti_flags &= ~TH_URG; 327 ti->ti_urp = 0; 328 } 329 } 330 /* 331 * If segment ends after window, drop trailing data 332 * (and PUSH and FIN); if nothing left, just ACK. 333 */ 334 todrop = (ti->ti_seq+ti->ti_len) - (tp->rcv_nxt+tp->rcv_wnd); 335 if (todrop > 0) { 336 if (todrop > ti->ti_len) 337 goto dropafterack; 338 m_adj(m, -todrop); 339 ti->ti_len -= todrop; 340 ti->ti_flags &= ~(TH_PUSH|TH_FIN); 341 } 342 } 343 344 /* 345 * If a segment is received on a connection after the 346 * user processes are gone, then RST the other end. 347 */ 348 if (so->so_state & SS_USERGONE) { 349 tcp_close(tp); 350 goto dropwithreset; 351 } 352 353 /* 354 * If the RST bit is set examine the state: 355 * SYN_RECEIVED STATE: 356 * If passive open, return to LISTEN state. 357 * If active open, inform user that connection was refused. 358 * ESTABLISHED, FIN_WAIT_1, FIN_WAIT2, CLOSE_WAIT STATES: 359 * Inform user that connection was reset, and close tcb. 360 * CLOSING, LAST_ACK, TIME_WAIT STATES 361 * Close the tcb. 362 */ 363 if (tiflags&TH_RST) switch (tp->t_state) { 364 365 case TCPS_SYN_RECEIVED: 366 if (inp->inp_socket->so_options & SO_ACCEPTCONN) { 367 /* a miniature tcp_close, but invisible to user */ 368 (void) m_free(dtom(tp->t_template)); 369 (void) m_free(dtom(tp)); 370 inp->inp_ppcb = 0; 371 tp = tcp_newtcpcb(inp); 372 tp->t_state = TCPS_LISTEN; 373 inp->inp_faddr.s_addr = 0; 374 inp->inp_fport = 0; 375 inp->inp_laddr.s_addr = 0; /* not quite right */ 376 goto drop; 377 } 378 tcp_drop(tp, ECONNREFUSED); 379 goto drop; 380 381 case TCPS_ESTABLISHED: 382 case TCPS_FIN_WAIT_1: 383 case TCPS_FIN_WAIT_2: 384 case TCPS_CLOSE_WAIT: 385 tcp_drop(tp, ECONNRESET); 386 goto drop; 387 388 case TCPS_CLOSING: 389 case TCPS_LAST_ACK: 390 case TCPS_TIME_WAIT: 391 tcp_close(tp); 392 goto drop; 393 } 394 395 /* 396 * If a SYN is in the window, then this is an 397 * error and we send an RST and drop the connection. 398 */ 399 if (tiflags & TH_SYN) { 400 tcp_drop(tp, ECONNRESET); 401 goto dropwithreset; 402 } 403 404 /* 405 * If the ACK bit is off we drop the segment and return. 406 */ 407 if ((tiflags & TH_ACK) == 0) 408 goto drop; 409 410 /* 411 * Ack processing. 412 */ 413 switch (tp->t_state) { 414 415 /* 416 * In SYN_RECEIVED state if the ack ACKs our SYN then enter 417 * ESTABLISHED state and continue processing, othewise 418 * send an RST. 419 */ 420 case TCPS_SYN_RECEIVED: 421 if (SEQ_GT(tp->snd_una, ti->ti_ack) || 422 SEQ_GT(ti->ti_ack, tp->snd_max)) 423 goto dropwithreset; 424 tp->snd_una++; /* SYN acked */ 425 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 426 tp->snd_nxt = tp->snd_una; 427 tp->t_timer[TCPT_REXMT] = 0; 428 if (so->so_options & SO_ACCEPTCONN) 429 so->so_state |= SS_CONNAWAITING; 430 soisconnected(so); 431 tp->t_state = TCPS_ESTABLISHED; 432 (void) tcp_reass(tp, (struct tcpiphdr *)0); 433 tp->snd_wl1 = ti->ti_seq - 1; 434 /* fall into ... */ 435 436 /* 437 * In ESTABLISHED state: drop duplicate ACKs; ACK out of range 438 * ACKs. If the ack is in the range 439 * tp->snd_una < ti->ti_ack <= tp->snd_max 440 * then advance tp->snd_una to ti->ti_ack and drop 441 * data from the retransmission queue. If this ACK reflects 442 * more up to date window information we update our window information. 443 */ 444 case TCPS_ESTABLISHED: 445 case TCPS_FIN_WAIT_1: 446 case TCPS_FIN_WAIT_2: 447 case TCPS_CLOSE_WAIT: 448 case TCPS_CLOSING: 449 case TCPS_LAST_ACK: 450 case TCPS_TIME_WAIT: 451 #define ourfinisacked (acked > 0) 452 453 if (SEQ_LEQ(ti->ti_ack, tp->snd_una)) 454 break; 455 if (SEQ_GT(ti->ti_ack, tp->snd_max)) 456 goto dropafterack; 457 acked = ti->ti_ack - tp->snd_una; 458 459 /* 460 * If transmit timer is running and timed sequence 461 * number was acked, update smoothed round trip time. 462 */ 463 if (tp->t_rtt && SEQ_GT(ti->ti_ack, tp->t_rtseq)) { 464 if (tp->t_srtt == 0) 465 tp->t_srtt = tp->t_rtt; 466 else 467 tp->t_srtt = 468 tcp_alpha * tp->t_srtt + 469 (1 - tcp_alpha) * tp->t_rtt; 470 /* printf("rtt %d srtt*100 now %d\n", tp->t_rtt, (int)(tp->t_srtt*100)); */ 471 tp->t_rtt = 0; 472 } 473 474 if (ti->ti_ack == tp->snd_max) 475 tp->t_timer[TCPT_REXMT] = 0; 476 else { 477 TCPT_RANGESET(tp->t_timer[TCPT_REXMT], 478 tcp_beta * tp->t_srtt, TCPTV_MIN, TCPTV_MAX); 479 tp->t_rtt = 1; 480 tp->t_rxtshift = 0; 481 } 482 if (acked > so->so_snd.sb_cc) { 483 sbdrop(&so->so_snd, so->so_snd.sb_cc); 484 tp->snd_wnd -= so->so_snd.sb_cc; 485 } else { 486 sbdrop(&so->so_snd.sb_cc, acked); 487 tp->snd_wnd -= acked; 488 acked = 0; 489 } 490 if (so->so_snd.sb_flags & SB_WAIT) 491 sowwakeup(so); 492 tp->snd_una = ti->ti_ack; 493 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 494 tp->snd_nxt = tp->snd_una; 495 496 switch (tp->t_state) { 497 498 /* 499 * In FIN_WAIT_1 STATE in addition to the processing 500 * for the ESTABLISHED state if our FIN is now acknowledged 501 * then enter FIN_WAIT_2. 502 */ 503 case TCPS_FIN_WAIT_1: 504 if (ourfinisacked) { 505 /* 506 * If we can't receive any more 507 * data, then closing user can proceed. 508 */ 509 if (so->so_state & SS_CANTRCVMORE) 510 soisdisconnected(so); 511 tp->t_state = TCPS_FIN_WAIT_2; 512 } 513 break; 514 515 /* 516 * In CLOSING STATE in addition to the processing for 517 * the ESTABLISHED state if the ACK acknowledges our FIN 518 * then enter the TIME-WAIT state, otherwise ignore 519 * the segment. 520 */ 521 case TCPS_CLOSING: 522 if (ourfinisacked) { 523 tp->t_state = TCPS_TIME_WAIT; 524 tcp_canceltimers(tp); 525 tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; 526 soisdisconnected(so); 527 } 528 break; 529 530 /* 531 * The only thing that can arrive in LAST_ACK state 532 * is an acknowledgment of our FIN. If our FIN is now 533 * acknowledged, delete the TCB, enter the closed state 534 * and return. 535 */ 536 case TCPS_LAST_ACK: 537 if (ourfinisacked) 538 tcp_close(tp); 539 goto drop; 540 541 /* 542 * In TIME_WAIT state the only thing that should arrive 543 * is a retransmission of the remote FIN. Acknowledge 544 * it and restart the finack timer. 545 */ 546 case TCPS_TIME_WAIT: 547 tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; 548 goto dropafterack; 549 } 550 #undef ourfinisacked 551 } 552 553 step6: 554 /* 555 * Update window information. 556 */ 557 if (SEQ_LT(tp->snd_wl1, ti->ti_seq) || tp->snd_wl1 == ti->ti_seq && 558 (SEQ_LT(tp->snd_wl2, ti->ti_ack) || 559 tp->snd_wl2 == ti->ti_ack && ti->ti_win > tp->snd_wnd)) { 560 tp->snd_wnd = ti->ti_win; 561 tp->snd_wl1 = ti->ti_seq; 562 tp->snd_wl2 = ti->ti_ack; 563 if (tp->snd_wnd > 0) 564 tp->t_timer[TCPT_PERSIST] = 0; 565 } 566 567 /* 568 * Process segments with URG. 569 */ 570 if ((tiflags & TH_URG) && TCPS_HAVERCVDFIN(tp->t_state) == 0) { 571 /* 572 * If this segment advances the known urgent pointer, 573 * then mark the data stream. This should not happen 574 * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since 575 * a FIN has been received from the remote side. 576 * In these states we ignore the URG. 577 */ 578 if (SEQ_GT(ti->ti_seq+ti->ti_urp, tp->rcv_up)) { 579 tp->rcv_up = ti->ti_seq + ti->ti_urp; 580 so->so_oobmark = so->so_rcv.sb_cc + 581 (tp->rcv_up - tp->rcv_nxt) - 1; 582 if (so->so_oobmark == 0) 583 so->so_state |= SS_RCVATMARK; 584 #ifdef TCPTRUEOOB 585 if ((tp->t_flags & TF_DOOOB) == 0) 586 #endif 587 sohasoutofband(so); 588 tp->t_oobflags &= ~TCPOOB_HAVEDATA; 589 } 590 /* 591 * Remove out of band data so doesn't get presented to user. 592 * This can happen independent of advancing the URG pointer, 593 * but if two URG's are pending at once, some out-of-band 594 * data may creep in... ick. 595 */ 596 if (ti->ti_urp <= ti->ti_len) { 597 tcp_pulloutofband(so, ti); 598 } 599 } 600 601 /* 602 * Process the segment text, merging it into the TCP sequencing queue, 603 * and arranging for acknowledgment of receipt if necessary. 604 * This process logically involves adjusting tp->rcv_wnd as data 605 * is presented to the user (this happens in tcp_usrreq.c, 606 * case PRU_RCVD). If a FIN has already been received on this 607 * connection then we just ignore the text. 608 */ 609 if ((ti->ti_len || (tiflags&TH_FIN)) && 610 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 611 tiflags = tcp_reass(tp, ti); 612 if (tcpnodelack == 0) 613 tp->t_flags |= TF_DELACK; 614 else 615 tp->t_flags |= TF_ACKNOW; 616 } else { 617 m_freem(m); 618 tiflags &= ~TH_FIN; 619 } 620 621 /* 622 * If FIN is received ACK the FIN and let the user know 623 * that the connection is closing. 624 */ 625 if (tiflags & TH_FIN) { 626 if (TCPS_HAVERCVDFIN(tp->t_state) == 0) { 627 socantrcvmore(so); 628 tp->t_flags |= TF_ACKNOW; 629 tp->rcv_nxt++; 630 } 631 switch (tp->t_state) { 632 633 /* 634 * In SYN_RECEIVED and ESTABLISHED STATES 635 * enter the CLOSE_WAIT state. 636 */ 637 case TCPS_SYN_RECEIVED: 638 case TCPS_ESTABLISHED: 639 tp->t_state = TCPS_CLOSE_WAIT; 640 break; 641 642 /* 643 * If still in FIN_WAIT_1 STATE FIN has not been acked so 644 * enter the CLOSING state. 645 */ 646 case TCPS_FIN_WAIT_1: 647 tp->t_state = TCPS_CLOSING; 648 break; 649 650 /* 651 * In FIN_WAIT_2 state enter the TIME_WAIT state, 652 * starting the time-wait timer, turning off the other 653 * standard timers. 654 */ 655 case TCPS_FIN_WAIT_2: 656 tp->t_state = TCPS_TIME_WAIT; 657 tcp_canceltimers(tp); 658 tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; 659 soisdisconnected(so); 660 break; 661 662 /* 663 * In TIME_WAIT state restart the 2 MSL time_wait timer. 664 */ 665 case TCPS_TIME_WAIT: 666 tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; 667 break; 668 } 669 } 670 if (so->so_options & SO_DEBUG) 671 tcp_trace(TA_INPUT, ostate, tp, &tcp_saveti, 0); 672 673 /* 674 * Return any desired output. 675 */ 676 tcp_output(tp); 677 return; 678 679 dropafterack: 680 /* 681 * Generate an ACK dropping incoming segment. 682 * Make ACK reflect our state. 683 */ 684 if (tiflags & TH_RST) 685 goto drop; 686 tcp_respond(tp, ti, tp->rcv_nxt, tp->snd_nxt, TH_ACK); 687 return; 688 689 dropwithreset: 690 if (om) 691 m_free(om); 692 /* 693 * Generate a RST, dropping incoming segment. 694 * Make ACK acceptable to originator of segment. 695 */ 696 if (tiflags & TH_RST) 697 goto drop; 698 if (tiflags & TH_ACK) 699 tcp_respond(tp, ti, (tcp_seq)0, ti->ti_ack, TH_RST); 700 else { 701 if (tiflags & TH_SYN) 702 ti->ti_len++; 703 tcp_respond(tp, ti, ti->ti_seq+ti->ti_len, (tcp_seq)0, TH_RST|TH_ACK); 704 } 705 return; 706 707 drop: 708 /* 709 * Drop space held by incoming segment and return. 710 */ 711 m_freem(m); 712 return; 713 } 714 715 tcp_dooptions(tp, om) 716 struct tcpcb *tp; 717 struct mbuf *om; 718 { 719 register u_char *cp; 720 int opt, optlen, cnt; 721 722 cp = mtod(om, u_char *); 723 cnt = om->m_len; 724 for (; cnt > 0; cnt -= optlen, cp += optlen) { 725 opt = cp[0]; 726 if (opt == TCPOPT_EOL) 727 break; 728 if (opt == TCPOPT_NOP) 729 optlen = 1; 730 else 731 optlen = cp[1]; 732 switch (opt) { 733 734 default: 735 break; 736 737 case TCPOPT_MAXSEG: 738 if (optlen != 4) 739 continue; 740 tp->t_maxseg = *(u_short *)(cp + 2); 741 #if vax 742 tp->t_maxseg = ntohs(tp->t_maxseg); 743 #endif 744 break; 745 746 #ifdef TCPTRUEOOB 747 case TCPOPT_WILLOOB: 748 tp->t_flags |= TF_DOOOB; 749 printf("tp %x dooob\n", tp); 750 break; 751 752 case TCPOPT_OOBDATA: { 753 int seq; 754 register struct socket *so = tp->t_inpcb->inp_socket; 755 tcp_seq mark; 756 757 if (optlen != 8) 758 continue; 759 seq = cp[2]; 760 if (seq < tp->t_iobseq) 761 seq += 256; 762 printf("oobdata cp[2] %d iobseq %d seq %d\n", cp[2], tp->t_iobseq, seq); 763 if (seq - tp->t_iobseq > 128) { 764 printf("bad seq\n"); 765 tp->t_oobflags |= TCPOOB_OWEACK; 766 break; 767 } 768 tp->t_iobseq = cp[2]; 769 tp->t_iobc = cp[3]; 770 mark = *(tcp_seq *)(cp + 4); 771 #if vax 772 mark = ntohl(mark); 773 #endif 774 so->so_oobmark = so->so_rcv.sb_cc + (mark-tp->rcv_nxt); 775 if (so->so_oobmark == 0) 776 so->so_state |= SS_RCVATMARK; 777 printf("take oob data %x input iobseq now %x\n", tp->t_iobc, tp->t_iobseq); 778 sohasoutofband(so); 779 break; 780 } 781 782 case TCPOPT_OOBACK: { 783 int seq; 784 785 if (optlen != 4) 786 continue; 787 if (tp->t_oobseq != cp[2]) { 788 printf("wrong ack\n"); 789 break; 790 } 791 printf("take oob ack %x and cancel rexmt\n", cp[2]); 792 tp->t_oobflags &= ~TCPOOB_NEEDACK; 793 tp->t_timer[TCPT_OOBREXMT] = 0; 794 break; 795 } 796 #endif TCPTRUEOOB 797 } 798 } 799 m_free(om); 800 } 801 802 /* 803 * Pull out of band byte out of a segment so 804 * it doesn't appear in the user's data queue. 805 * It is still reflected in the segment length for 806 * sequencing purposes. 807 */ 808 tcp_pulloutofband(so, ti) 809 struct socket *so; 810 struct tcpiphdr *ti; 811 { 812 register struct mbuf *m; 813 int cnt = ti->ti_urp - 1; 814 815 m = dtom(ti); 816 while (cnt >= 0) { 817 if (m->m_len > cnt) { 818 char *cp = mtod(m, caddr_t) + cnt; 819 struct tcpcb *tp = sototcpcb(so); 820 821 tp->t_iobc = *cp; 822 tp->t_oobflags |= TCPOOB_HAVEDATA; 823 bcopy(cp+1, cp, m->m_len - cnt - 1); 824 m->m_len--; 825 return; 826 } 827 cnt -= m->m_len; 828 m = m->m_next; 829 if (m == 0) 830 break; 831 } 832 panic("tcp_pulloutofband"); 833 } 834 835 /* 836 * Insert segment ti into reassembly queue of tcp with 837 * control block tp. Return TH_FIN if reassembly now includes 838 * a segment with FIN. 839 */ 840 tcp_reass(tp, ti) 841 register struct tcpcb *tp; 842 register struct tcpiphdr *ti; 843 { 844 register struct tcpiphdr *q; 845 struct socket *so = tp->t_inpcb->inp_socket; 846 struct mbuf *m; 847 int flags; 848 COUNT(TCP_REASS); 849 850 /* 851 * Call with ti==0 after become established to 852 * force pre-ESTABLISHED data up to user socket. 853 */ 854 if (ti == 0) 855 goto present; 856 857 /* 858 * Find a segment which begins after this one does. 859 */ 860 for (q = tp->seg_next; q != (struct tcpiphdr *)tp; 861 q = (struct tcpiphdr *)q->ti_next) 862 if (SEQ_GT(q->ti_seq, ti->ti_seq)) 863 break; 864 865 /* 866 * If there is a preceding segment, it may provide some of 867 * our data already. If so, drop the data from the incoming 868 * segment. If it provides all of our data, drop us. 869 */ 870 if ((struct tcpiphdr *)q->ti_prev != (struct tcpiphdr *)tp) { 871 register int i; 872 q = (struct tcpiphdr *)q->ti_prev; 873 /* conversion to int (in i) handles seq wraparound */ 874 i = q->ti_seq + q->ti_len - ti->ti_seq; 875 if (i > 0) { 876 if (i >= ti->ti_len) 877 goto drop; 878 m_adj(dtom(tp), i); 879 ti->ti_len -= i; 880 ti->ti_seq += i; 881 } 882 q = (struct tcpiphdr *)(q->ti_next); 883 } 884 885 /* 886 * While we overlap succeeding segments trim them or, 887 * if they are completely covered, dequeue them. 888 */ 889 while (q != (struct tcpiphdr *)tp) { 890 register int i = (ti->ti_seq + ti->ti_len) - q->ti_seq; 891 if (i <= 0) 892 break; 893 if (i < q->ti_len) { 894 q->ti_seq += i; 895 q->ti_len -= i; 896 m_adj(dtom(q), i); 897 break; 898 } 899 q = (struct tcpiphdr *)q->ti_next; 900 m = dtom(q->ti_prev); 901 remque(q->ti_prev); 902 m_freem(m); 903 } 904 905 /* 906 * Stick new segment in its place. 907 */ 908 insque(ti, q->ti_prev); 909 910 present: 911 /* 912 * Present data to user, advancing rcv_nxt through 913 * completed sequence space. 914 */ 915 if (TCPS_HAVERCVDSYN(tp->t_state) == 0) 916 return (0); 917 ti = tp->seg_next; 918 if (ti == (struct tcpiphdr *)tp || ti->ti_seq != tp->rcv_nxt) 919 return (0); 920 if (tp->t_state == TCPS_SYN_RECEIVED && ti->ti_len) 921 return (0); 922 do { 923 tp->rcv_nxt += ti->ti_len; 924 flags = ti->ti_flags & TH_FIN; 925 remque(ti); 926 m = dtom(ti); 927 ti = (struct tcpiphdr *)ti->ti_next; 928 if (so->so_state & SS_CANTRCVMORE) 929 (void) m_freem(m); 930 else 931 sbappend(&so->so_rcv, m); 932 } while (ti != (struct tcpiphdr *)tp && ti->ti_seq == tp->rcv_nxt); 933 sorwakeup(so); 934 return (flags); 935 drop: 936 m_freem(dtom(ti)); 937 return (0); 938 } 939