1 /* tcp_input.c 1.72 82/07/21 */ 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 if (so->so_options & SO_ACCEPTCONN) { 158 so = sonewconn(so); 159 if (so == 0) 160 goto drop; 161 inp = (struct inpcb *)so->so_pcb; 162 inp->inp_laddr = ti->ti_dst; 163 inp->inp_lport = ti->ti_dport; 164 tp = intotcpcb(inp); 165 tp->t_state = TCPS_LISTEN; 166 } 167 168 /* 169 * Segment received on connection. 170 * Reset idle time and keep-alive timer. 171 */ 172 tp->t_idle = 0; 173 tp->t_timer[TCPT_KEEP] = TCPTV_KEEP; 174 175 /* 176 * Process options. 177 */ 178 if (om) { 179 tcp_dooptions(tp, om); 180 om = 0; 181 } 182 183 /* 184 * Calculate amount of space in receive window, 185 * and then do TCP input processing. 186 */ 187 tp->rcv_wnd = sbspace(&so->so_rcv); 188 if (tp->rcv_wnd < 0) 189 tp->rcv_wnd = 0; 190 191 switch (tp->t_state) { 192 193 /* 194 * If the state is LISTEN then ignore segment if it contains an RST. 195 * If the segment contains an ACK then it is bad and send a RST. 196 * If it does not contain a SYN then it is not interesting; drop it. 197 * Otherwise initialize tp->rcv_nxt, and tp->irs, select an initial 198 * tp->iss, and send a segment: 199 * <SEQ=ISS><ACK=RCV_NXT><CTL=SYN,ACK> 200 * Also initialize tp->snd_nxt to tp->iss+1 and tp->snd_una to tp->iss. 201 * Fill in remote peer address fields if not previously specified. 202 * Enter SYN_RECEIVED state, and process any other fields of this 203 * segment in this state. 204 */ 205 case TCPS_LISTEN: 206 if (tiflags & TH_RST) 207 goto drop; 208 if (tiflags & TH_ACK) 209 goto dropwithreset; 210 if ((tiflags & TH_SYN) == 0) 211 goto drop; 212 tcp_in.sin_addr = ti->ti_src; 213 tcp_in.sin_port = ti->ti_sport; 214 laddr = inp->inp_laddr; 215 if (inp->inp_laddr.s_addr == 0) 216 inp->inp_laddr = ti->ti_dst; 217 if (in_pcbconnect(inp, (struct sockaddr_in *)&tcp_in)) { 218 inp->inp_laddr = laddr; 219 goto drop; 220 } 221 tp->t_template = tcp_template(tp); 222 if (tp->t_template == 0) { 223 in_pcbdisconnect(inp); 224 inp->inp_laddr = laddr; 225 tp = 0; 226 goto drop; 227 } 228 tp->iss = tcp_iss; tcp_iss += TCP_ISSINCR/2; 229 tp->irs = ti->ti_seq; 230 tcp_sendseqinit(tp); 231 tcp_rcvseqinit(tp); 232 tp->t_state = TCPS_SYN_RECEIVED; 233 tp->t_timer[TCPT_KEEP] = TCPTV_KEEP; 234 goto trimthenstep6; 235 236 /* 237 * If the state is SYN_SENT: 238 * if seg contains an ACK, but not for our SYN, drop the input. 239 * if seg contains a RST, then drop the connection. 240 * if seg does not contain SYN, then drop it. 241 * Otherwise this is an acceptable SYN segment 242 * initialize tp->rcv_nxt and tp->irs 243 * if seg contains ack then advance tp->snd_una 244 * if SYN has been acked change to ESTABLISHED else SYN_RCVD state 245 * arrange for segment to be acked (eventually) 246 * continue processing rest of data/controls, beginning with URG 247 */ 248 case TCPS_SYN_SENT: 249 if ((tiflags & TH_ACK) && 250 /* this should be SEQ_LT; is SEQ_LEQ for BBN vax TCP only */ 251 (SEQ_LT(ti->ti_ack, tp->iss) || 252 SEQ_GT(ti->ti_ack, tp->snd_max))) 253 goto dropwithreset; 254 if (tiflags & TH_RST) { 255 if (tiflags & TH_ACK) { 256 tcp_drop(tp, ECONNREFUSED); 257 tp = 0; 258 } 259 goto drop; 260 } 261 if ((tiflags & TH_SYN) == 0) 262 goto drop; 263 tp->snd_una = ti->ti_ack; 264 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 265 tp->snd_nxt = tp->snd_una; 266 tp->t_timer[TCPT_REXMT] = 0; 267 tp->irs = ti->ti_seq; 268 tcp_rcvseqinit(tp); 269 tp->t_flags |= TF_ACKNOW; 270 if (SEQ_GT(tp->snd_una, tp->iss)) { 271 soisconnected(so); 272 tp->t_state = TCPS_ESTABLISHED; 273 (void) tcp_reass(tp, (struct tcpiphdr *)0); 274 } else 275 tp->t_state = TCPS_SYN_RECEIVED; 276 goto trimthenstep6; 277 278 trimthenstep6: 279 /* 280 * Advance ti->ti_seq to correspond to first data byte. 281 * If data, trim to stay within window, 282 * dropping FIN if necessary. 283 */ 284 ti->ti_seq++; 285 if (ti->ti_len > tp->rcv_wnd) { 286 todrop = ti->ti_len - tp->rcv_wnd; 287 m_adj(m, -todrop); 288 ti->ti_len = tp->rcv_wnd; 289 ti->ti_flags &= ~TH_FIN; 290 } 291 tp->snd_wl1 = ti->ti_seq - 1; 292 goto step6; 293 } 294 295 /* 296 * States other than LISTEN or SYN_SENT. 297 * First check that at least some bytes of segment are within 298 * receive window. 299 */ 300 if (tp->rcv_wnd == 0) { 301 /* 302 * If window is closed can only take segments at 303 * window edge, and have to drop data and PUSH from 304 * incoming segments. 305 */ 306 if (tp->rcv_nxt != ti->ti_seq) 307 goto dropafterack; 308 if (ti->ti_len > 0) { 309 m_adj(m, ti->ti_len); 310 ti->ti_len = 0; 311 ti->ti_flags &= ~(TH_PUSH|TH_FIN); 312 } 313 } else { 314 /* 315 * If segment begins before rcv_nxt, drop leading 316 * data (and SYN); if nothing left, just ack. 317 */ 318 todrop = tp->rcv_nxt - ti->ti_seq; 319 if (todrop > 0) { 320 if (tiflags & TH_SYN) { 321 tiflags &= ~TH_SYN; 322 ti->ti_flags &= ~TH_SYN; 323 ti->ti_seq++; 324 if (ti->ti_urp > 1) 325 ti->ti_urp--; 326 else 327 tiflags &= ~TH_URG; 328 todrop--; 329 } 330 if (todrop > ti->ti_len || 331 todrop == ti->ti_len && (tiflags&TH_FIN) == 0) 332 goto dropafterack; 333 m_adj(m, todrop); 334 ti->ti_seq += todrop; 335 ti->ti_len -= todrop; 336 if (ti->ti_urp > todrop) 337 ti->ti_urp -= todrop; 338 else { 339 tiflags &= ~TH_URG; 340 ti->ti_flags &= ~TH_URG; 341 ti->ti_urp = 0; 342 } 343 } 344 /* 345 * If segment ends after window, drop trailing data 346 * (and PUSH and FIN); if nothing left, just ACK. 347 */ 348 todrop = (ti->ti_seq+ti->ti_len) - (tp->rcv_nxt+tp->rcv_wnd); 349 if (todrop > 0) { 350 if (todrop >= ti->ti_len) 351 goto dropafterack; 352 m_adj(m, -todrop); 353 ti->ti_len -= todrop; 354 ti->ti_flags &= ~(TH_PUSH|TH_FIN); 355 } 356 } 357 358 /* 359 * If a segment is received on a connection after the 360 * user processes are gone, then RST the other end. 361 */ 362 if (so->so_state & SS_NOFDREF) { 363 tcp_close(tp); 364 tp = 0; 365 goto dropwithreset; 366 } 367 368 /* 369 * If the RST bit is set examine the state: 370 * SYN_RECEIVED STATE: 371 * If passive open, return to LISTEN state. 372 * If active open, inform user that connection was refused. 373 * ESTABLISHED, FIN_WAIT_1, FIN_WAIT2, CLOSE_WAIT STATES: 374 * Inform user that connection was reset, and close tcb. 375 * CLOSING, LAST_ACK, TIME_WAIT STATES 376 * Close the tcb. 377 */ 378 if (tiflags&TH_RST) switch (tp->t_state) { 379 380 case TCPS_SYN_RECEIVED: 381 tcp_drop(tp, ECONNREFUSED); 382 tp = 0; 383 goto drop; 384 385 case TCPS_ESTABLISHED: 386 case TCPS_FIN_WAIT_1: 387 case TCPS_FIN_WAIT_2: 388 case TCPS_CLOSE_WAIT: 389 tcp_drop(tp, ECONNRESET); 390 tp = 0; 391 goto drop; 392 393 case TCPS_CLOSING: 394 case TCPS_LAST_ACK: 395 case TCPS_TIME_WAIT: 396 tcp_close(tp); 397 tp = 0; 398 goto drop; 399 } 400 401 /* 402 * If a SYN is in the window, then this is an 403 * error and we send an RST and drop the connection. 404 */ 405 if (tiflags & TH_SYN) { 406 tcp_drop(tp, ECONNRESET); 407 tp = 0; 408 goto dropwithreset; 409 } 410 411 /* 412 * If the ACK bit is off we drop the segment and return. 413 */ 414 if ((tiflags & TH_ACK) == 0) 415 goto drop; 416 417 /* 418 * Ack processing. 419 */ 420 switch (tp->t_state) { 421 422 /* 423 * In SYN_RECEIVED state if the ack ACKs our SYN then enter 424 * ESTABLISHED state and continue processing, othewise 425 * send an RST. 426 */ 427 case TCPS_SYN_RECEIVED: 428 if (SEQ_GT(tp->snd_una, ti->ti_ack) || 429 SEQ_GT(ti->ti_ack, tp->snd_max)) 430 goto dropwithreset; 431 tp->snd_una++; /* SYN acked */ 432 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 433 tp->snd_nxt = tp->snd_una; 434 tp->t_timer[TCPT_REXMT] = 0; 435 soisconnected(so); 436 tp->t_state = TCPS_ESTABLISHED; 437 (void) tcp_reass(tp, (struct tcpiphdr *)0); 438 tp->snd_wl1 = ti->ti_seq - 1; 439 /* fall into ... */ 440 441 /* 442 * In ESTABLISHED state: drop duplicate ACKs; ACK out of range 443 * ACKs. If the ack is in the range 444 * tp->snd_una < ti->ti_ack <= tp->snd_max 445 * then advance tp->snd_una to ti->ti_ack and drop 446 * data from the retransmission queue. If this ACK reflects 447 * more up to date window information we update our window information. 448 */ 449 case TCPS_ESTABLISHED: 450 case TCPS_FIN_WAIT_1: 451 case TCPS_FIN_WAIT_2: 452 case TCPS_CLOSE_WAIT: 453 case TCPS_CLOSING: 454 case TCPS_LAST_ACK: 455 case TCPS_TIME_WAIT: 456 #define ourfinisacked (acked > 0) 457 458 if (SEQ_LEQ(ti->ti_ack, tp->snd_una)) 459 break; 460 if (SEQ_GT(ti->ti_ack, tp->snd_max)) 461 goto dropafterack; 462 acked = ti->ti_ack - tp->snd_una; 463 464 /* 465 * If transmit timer is running and timed sequence 466 * number was acked, update smoothed round trip time. 467 */ 468 if (tp->t_rtt && SEQ_GT(ti->ti_ack, tp->t_rtseq)) { 469 if (tp->t_srtt == 0) 470 tp->t_srtt = tp->t_rtt; 471 else 472 tp->t_srtt = 473 tcp_alpha * tp->t_srtt + 474 (1 - tcp_alpha) * tp->t_rtt; 475 /* printf("rtt %d srtt*100 now %d\n", tp->t_rtt, (int)(tp->t_srtt*100)); */ 476 tp->t_rtt = 0; 477 } 478 479 if (ti->ti_ack == tp->snd_max) 480 tp->t_timer[TCPT_REXMT] = 0; 481 else { 482 TCPT_RANGESET(tp->t_timer[TCPT_REXMT], 483 tcp_beta * tp->t_srtt, TCPTV_MIN, TCPTV_MAX); 484 tp->t_rtt = 1; 485 tp->t_rxtshift = 0; 486 } 487 if (acked > so->so_snd.sb_cc) { 488 sbdrop(&so->so_snd, so->so_snd.sb_cc); 489 tp->snd_wnd -= so->so_snd.sb_cc; 490 } else { 491 sbdrop(&so->so_snd, acked); 492 tp->snd_wnd -= acked; 493 acked = 0; 494 } 495 if ((so->so_snd.sb_flags & SB_WAIT) || so->so_snd.sb_sel) 496 sowwakeup(so); 497 tp->snd_una = ti->ti_ack; 498 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 499 tp->snd_nxt = tp->snd_una; 500 501 switch (tp->t_state) { 502 503 /* 504 * In FIN_WAIT_1 STATE in addition to the processing 505 * for the ESTABLISHED state if our FIN is now acknowledged 506 * then enter FIN_WAIT_2. 507 */ 508 case TCPS_FIN_WAIT_1: 509 if (ourfinisacked) { 510 /* 511 * If we can't receive any more 512 * data, then closing user can proceed. 513 */ 514 if (so->so_state & SS_CANTRCVMORE) 515 soisdisconnected(so); 516 tp->t_state = TCPS_FIN_WAIT_2; 517 } 518 break; 519 520 /* 521 * In CLOSING STATE in addition to the processing for 522 * the ESTABLISHED state if the ACK acknowledges our FIN 523 * then enter the TIME-WAIT state, otherwise ignore 524 * the segment. 525 */ 526 case TCPS_CLOSING: 527 if (ourfinisacked) { 528 tp->t_state = TCPS_TIME_WAIT; 529 tcp_canceltimers(tp); 530 tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; 531 soisdisconnected(so); 532 } 533 break; 534 535 /* 536 * The only thing that can arrive in LAST_ACK state 537 * is an acknowledgment of our FIN. If our FIN is now 538 * acknowledged, delete the TCB, enter the closed state 539 * and return. 540 */ 541 case TCPS_LAST_ACK: 542 if (ourfinisacked) { 543 tcp_close(tp); 544 tp = 0; 545 } 546 goto drop; 547 548 /* 549 * In TIME_WAIT state the only thing that should arrive 550 * is a retransmission of the remote FIN. Acknowledge 551 * it and restart the finack timer. 552 */ 553 case TCPS_TIME_WAIT: 554 tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; 555 goto dropafterack; 556 } 557 #undef ourfinisacked 558 } 559 560 step6: 561 /* 562 * Update window information. 563 */ 564 if (SEQ_LT(tp->snd_wl1, ti->ti_seq) || tp->snd_wl1 == ti->ti_seq && 565 (SEQ_LT(tp->snd_wl2, ti->ti_ack) || 566 tp->snd_wl2 == ti->ti_ack && ti->ti_win > tp->snd_wnd)) { 567 tp->snd_wnd = ti->ti_win; 568 tp->snd_wl1 = ti->ti_seq; 569 tp->snd_wl2 = ti->ti_ack; 570 if (tp->snd_wnd > 0) 571 tp->t_timer[TCPT_PERSIST] = 0; 572 } 573 574 /* 575 * Process segments with URG. 576 */ 577 if ((tiflags & TH_URG) && ti->ti_urp && 578 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 579 /* 580 * If this segment advances the known urgent pointer, 581 * then mark the data stream. This should not happen 582 * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since 583 * a FIN has been received from the remote side. 584 * In these states we ignore the URG. 585 */ 586 if (SEQ_GT(ti->ti_seq+ti->ti_urp, tp->rcv_up)) { 587 tp->rcv_up = ti->ti_seq + ti->ti_urp; 588 so->so_oobmark = so->so_rcv.sb_cc + 589 (tp->rcv_up - tp->rcv_nxt) - 1; 590 if (so->so_oobmark == 0) 591 so->so_state |= SS_RCVATMARK; 592 #ifdef TCPTRUEOOB 593 if ((tp->t_flags & TF_DOOOB) == 0) 594 #endif 595 sohasoutofband(so); 596 tp->t_oobflags &= ~TCPOOB_HAVEDATA; 597 } 598 /* 599 * Remove out of band data so doesn't get presented to user. 600 * This can happen independent of advancing the URG pointer, 601 * but if two URG's are pending at once, some out-of-band 602 * data may creep in... ick. 603 */ 604 if (ti->ti_urp <= ti->ti_len) 605 tcp_pulloutofband(so, ti); 606 } 607 608 /* 609 * Process the segment text, merging it into the TCP sequencing queue, 610 * and arranging for acknowledgment of receipt if necessary. 611 * This process logically involves adjusting tp->rcv_wnd as data 612 * is presented to the user (this happens in tcp_usrreq.c, 613 * case PRU_RCVD). If a FIN has already been received on this 614 * connection then we just ignore the text. 615 */ 616 if ((ti->ti_len || (tiflags&TH_FIN)) && 617 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 618 tiflags = tcp_reass(tp, ti); 619 if (tcpnodelack == 0) 620 tp->t_flags |= TF_DELACK; 621 else 622 tp->t_flags |= TF_ACKNOW; 623 } else { 624 m_freem(m); 625 tiflags &= ~TH_FIN; 626 } 627 628 /* 629 * If FIN is received ACK the FIN and let the user know 630 * that the connection is closing. 631 */ 632 if (tiflags & TH_FIN) { 633 if (TCPS_HAVERCVDFIN(tp->t_state) == 0) { 634 socantrcvmore(so); 635 tp->t_flags |= TF_ACKNOW; 636 tp->rcv_nxt++; 637 } 638 switch (tp->t_state) { 639 640 /* 641 * In SYN_RECEIVED and ESTABLISHED STATES 642 * enter the CLOSE_WAIT state. 643 */ 644 case TCPS_SYN_RECEIVED: 645 case TCPS_ESTABLISHED: 646 tp->t_state = TCPS_CLOSE_WAIT; 647 break; 648 649 /* 650 * If still in FIN_WAIT_1 STATE FIN has not been acked so 651 * enter the CLOSING state. 652 */ 653 case TCPS_FIN_WAIT_1: 654 tp->t_state = TCPS_CLOSING; 655 break; 656 657 /* 658 * In FIN_WAIT_2 state enter the TIME_WAIT state, 659 * starting the time-wait timer, turning off the other 660 * standard timers. 661 */ 662 case TCPS_FIN_WAIT_2: 663 tp->t_state = TCPS_TIME_WAIT; 664 tcp_canceltimers(tp); 665 tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; 666 soisdisconnected(so); 667 break; 668 669 /* 670 * In TIME_WAIT state restart the 2 MSL time_wait timer. 671 */ 672 case TCPS_TIME_WAIT: 673 tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; 674 break; 675 } 676 } 677 if (so->so_options & SO_DEBUG) 678 tcp_trace(TA_INPUT, ostate, tp, &tcp_saveti, 0); 679 680 /* 681 * Return any desired output. 682 */ 683 (void) tcp_output(tp); 684 return; 685 686 dropafterack: 687 /* 688 * Generate an ACK dropping incoming segment if it occupies 689 * sequence space, where the ACK reflects our state. 690 */ 691 if ((tiflags&TH_RST) || 692 tlen == 0 && (tiflags&(TH_SYN|TH_FIN)) == 0) 693 goto drop; 694 if (tp->t_inpcb->inp_socket->so_options & SO_DEBUG) 695 tcp_trace(TA_RESPOND, ostate, tp, &tcp_saveti, 0); 696 tcp_respond(tp, ti, tp->rcv_nxt, tp->snd_nxt, TH_ACK); 697 return; 698 699 dropwithreset: 700 if (om) 701 (void) m_free(om); 702 /* 703 * Generate a RST, dropping incoming segment. 704 * Make ACK acceptable to originator of segment. 705 */ 706 if (tiflags & TH_RST) 707 goto drop; 708 if (tiflags & TH_ACK) 709 tcp_respond(tp, ti, (tcp_seq)0, ti->ti_ack, TH_RST); 710 else { 711 if (tiflags & TH_SYN) 712 ti->ti_len++; 713 tcp_respond(tp, ti, ti->ti_seq+ti->ti_len, (tcp_seq)0, 714 TH_RST|TH_ACK); 715 } 716 return; 717 718 drop: 719 /* 720 * Drop space held by incoming segment and return. 721 */ 722 if (tp && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) 723 tcp_trace(TA_DROP, ostate, tp, &tcp_saveti, 0); 724 m_freem(m); 725 return; 726 } 727 728 tcp_dooptions(tp, om) 729 struct tcpcb *tp; 730 struct mbuf *om; 731 { 732 register u_char *cp; 733 int opt, optlen, cnt; 734 735 cp = mtod(om, u_char *); 736 cnt = om->m_len; 737 for (; cnt > 0; cnt -= optlen, cp += optlen) { 738 opt = cp[0]; 739 if (opt == TCPOPT_EOL) 740 break; 741 if (opt == TCPOPT_NOP) 742 optlen = 1; 743 else 744 optlen = cp[1]; 745 switch (opt) { 746 747 default: 748 break; 749 750 case TCPOPT_MAXSEG: 751 if (optlen != 4) 752 continue; 753 tp->t_maxseg = *(u_short *)(cp + 2); 754 #if vax || pdp11 755 tp->t_maxseg = ntohs((u_short)tp->t_maxseg); 756 #endif 757 break; 758 759 #ifdef TCPTRUEOOB 760 case TCPOPT_WILLOOB: 761 tp->t_flags |= TF_DOOOB; 762 printf("tp %x dooob\n", tp); 763 break; 764 765 case TCPOPT_OOBDATA: { 766 int seq; 767 register struct socket *so = tp->t_inpcb->inp_socket; 768 tcp_seq mark; 769 770 if (optlen != 8) 771 continue; 772 seq = cp[2]; 773 if (seq < tp->t_iobseq) 774 seq += 256; 775 printf("oobdata cp[2] %d iobseq %d seq %d\n", cp[2], tp->t_iobseq, seq); 776 if (seq - tp->t_iobseq > 128) { 777 printf("bad seq\n"); 778 tp->t_oobflags |= TCPOOB_OWEACK; 779 break; 780 } 781 tp->t_iobseq = cp[2]; 782 tp->t_iobc = cp[3]; 783 mark = *(tcp_seq *)(cp + 4); 784 #if vax || pdp11 785 mark = ntohl(mark); 786 #endif 787 so->so_oobmark = so->so_rcv.sb_cc + (mark-tp->rcv_nxt); 788 if (so->so_oobmark == 0) 789 so->so_state |= SS_RCVATMARK; 790 printf("take oob data %x input iobseq now %x\n", tp->t_iobc, tp->t_iobseq); 791 sohasoutofband(so); 792 break; 793 } 794 795 case TCPOPT_OOBACK: { 796 int seq; 797 798 if (optlen != 4) 799 continue; 800 if (tp->t_oobseq != cp[2]) { 801 printf("wrong ack\n"); 802 break; 803 } 804 printf("take oob ack %x and cancel rexmt\n", cp[2]); 805 tp->t_oobflags &= ~TCPOOB_NEEDACK; 806 tp->t_timer[TCPT_OOBREXMT] = 0; 807 break; 808 } 809 #endif TCPTRUEOOB 810 } 811 } 812 (void) m_free(om); 813 } 814 815 /* 816 * Pull out of band byte out of a segment so 817 * it doesn't appear in the user's data queue. 818 * It is still reflected in the segment length for 819 * sequencing purposes. 820 */ 821 tcp_pulloutofband(so, ti) 822 struct socket *so; 823 struct tcpiphdr *ti; 824 { 825 register struct mbuf *m; 826 int cnt = ti->ti_urp - 1; 827 828 m = dtom(ti); 829 while (cnt >= 0) { 830 if (m->m_len > cnt) { 831 char *cp = mtod(m, caddr_t) + cnt; 832 struct tcpcb *tp = sototcpcb(so); 833 834 tp->t_iobc = *cp; 835 tp->t_oobflags |= TCPOOB_HAVEDATA; 836 bcopy(cp+1, cp, (unsigned)(m->m_len - cnt - 1)); 837 m->m_len--; 838 return; 839 } 840 cnt -= m->m_len; 841 m = m->m_next; 842 if (m == 0) 843 break; 844 } 845 panic("tcp_pulloutofband"); 846 } 847 848 /* 849 * Insert segment ti into reassembly queue of tcp with 850 * control block tp. Return TH_FIN if reassembly now includes 851 * a segment with FIN. 852 */ 853 tcp_reass(tp, ti) 854 register struct tcpcb *tp; 855 register struct tcpiphdr *ti; 856 { 857 register struct tcpiphdr *q; 858 struct socket *so = tp->t_inpcb->inp_socket; 859 struct mbuf *m; 860 int flags; 861 862 /* 863 * Call with ti==0 after become established to 864 * force pre-ESTABLISHED data up to user socket. 865 */ 866 if (ti == 0) 867 goto present; 868 869 /* 870 * Find a segment which begins after this one does. 871 */ 872 for (q = tp->seg_next; q != (struct tcpiphdr *)tp; 873 q = (struct tcpiphdr *)q->ti_next) 874 if (SEQ_GT(q->ti_seq, ti->ti_seq)) 875 break; 876 877 /* 878 * If there is a preceding segment, it may provide some of 879 * our data already. If so, drop the data from the incoming 880 * segment. If it provides all of our data, drop us. 881 */ 882 if ((struct tcpiphdr *)q->ti_prev != (struct tcpiphdr *)tp) { 883 register int i; 884 q = (struct tcpiphdr *)q->ti_prev; 885 /* conversion to int (in i) handles seq wraparound */ 886 i = q->ti_seq + q->ti_len - ti->ti_seq; 887 if (i > 0) { 888 if (i >= ti->ti_len) 889 goto drop; 890 m_adj(dtom(ti), i); 891 ti->ti_len -= i; 892 ti->ti_seq += i; 893 } 894 q = (struct tcpiphdr *)(q->ti_next); 895 } 896 897 /* 898 * While we overlap succeeding segments trim them or, 899 * if they are completely covered, dequeue them. 900 */ 901 while (q != (struct tcpiphdr *)tp) { 902 register int i = (ti->ti_seq + ti->ti_len) - q->ti_seq; 903 if (i <= 0) 904 break; 905 if (i < q->ti_len) { 906 q->ti_seq += i; 907 q->ti_len -= i; 908 m_adj(dtom(q), i); 909 break; 910 } 911 q = (struct tcpiphdr *)q->ti_next; 912 m = dtom(q->ti_prev); 913 remque(q->ti_prev); 914 m_freem(m); 915 } 916 917 /* 918 * Stick new segment in its place. 919 */ 920 insque(ti, q->ti_prev); 921 922 present: 923 /* 924 * Present data to user, advancing rcv_nxt through 925 * completed sequence space. 926 */ 927 if (TCPS_HAVERCVDSYN(tp->t_state) == 0) 928 return (0); 929 ti = tp->seg_next; 930 if (ti == (struct tcpiphdr *)tp || ti->ti_seq != tp->rcv_nxt) 931 return (0); 932 if (tp->t_state == TCPS_SYN_RECEIVED && ti->ti_len) 933 return (0); 934 do { 935 tp->rcv_nxt += ti->ti_len; 936 flags = ti->ti_flags & TH_FIN; 937 remque(ti); 938 m = dtom(ti); 939 ti = (struct tcpiphdr *)ti->ti_next; 940 if (so->so_state & SS_CANTRCVMORE) 941 m_freem(m); 942 else 943 sbappend(&so->so_rcv, m); 944 } while (ti != (struct tcpiphdr *)tp && ti->ti_seq == tp->rcv_nxt); 945 sorwakeup(so); 946 return (flags); 947 drop: 948 m_freem(dtom(ti)); 949 return (0); 950 } 951