1 /* tcp_input.c 1.60 82/03/13 */ 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 #ifdef notdef 25 int tcpprintfs = 0; 26 #endif 27 int tcpcksum = 1; 28 struct sockaddr_in tcp_in = { AF_INET }; 29 struct tcpiphdr tcp_saveti; 30 extern tcpnodelack; 31 32 struct tcpcb *tcp_newtcpcb(); 33 /* 34 * TCP input routine, follows pages 65-76 of the 35 * protocol specification dated September, 1981 very closely. 36 */ 37 tcp_input(m0) 38 struct mbuf *m0; 39 { 40 register struct tcpiphdr *ti; 41 struct inpcb *inp; 42 register struct mbuf *m; 43 struct mbuf *om = 0; 44 int len, tlen, off; 45 register struct tcpcb *tp = 0; 46 register int tiflags; 47 struct socket *so; 48 int todrop, acked; 49 short ostate; 50 struct in_addr laddr; 51 52 COUNT(TCP_INPUT); 53 /* 54 * Get IP and TCP header together in first mbuf. 55 * Note: IP leaves IP header in first mbuf. 56 */ 57 m = m0; 58 ti = mtod(m, struct tcpiphdr *); 59 if (((struct ip *)ti)->ip_hl > (sizeof (struct ip) >> 2)) 60 ip_stripoptions((struct ip *)ti, (struct mbuf *)0); 61 if (m->m_off > MMAXOFF || m->m_len < sizeof (struct tcpiphdr)) { 62 if ((m = m_pullup(m, sizeof (struct tcpiphdr))) == 0) { 63 tcpstat.tcps_hdrops++; 64 return; 65 } 66 ti = mtod(m, struct tcpiphdr *); 67 } 68 69 /* 70 * Checksum extended TCP header and data. 71 */ 72 tlen = ((struct ip *)ti)->ip_len; 73 len = sizeof (struct ip) + tlen; 74 if (tcpcksum) { 75 ti->ti_next = ti->ti_prev = 0; 76 ti->ti_x1 = 0; 77 ti->ti_len = (u_short)tlen; 78 #if vax 79 ti->ti_len = htons((u_short)ti->ti_len); 80 #endif 81 if (ti->ti_sum = in_cksum(m, len)) { 82 tcpstat.tcps_badsum++; 83 printf("tcp cksum %x\n", ti->ti_sum); 84 goto drop; 85 } 86 } 87 88 /* 89 * Check that TCP offset makes sense, 90 * pull out TCP options and adjust length. 91 */ 92 off = ti->ti_off << 2; 93 if (off < sizeof (struct tcphdr) || off > tlen) { 94 tcpstat.tcps_badoff++; 95 goto drop; 96 } 97 ti->ti_len = tlen - off; 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 IP header 120 */ 121 off += sizeof (struct ip); 122 m->m_off += off; 123 m->m_len -= off; 124 125 #if vax 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 goto drop; 216 } 217 in_setsockaddr(inp); 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 goto drop; 248 } 249 if ((tiflags & TH_SYN) == 0) 250 goto drop; 251 tp->snd_una = ti->ti_ack; 252 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 253 tp->snd_nxt = tp->snd_una; 254 tp->t_timer[TCPT_REXMT] = 0; 255 tp->irs = ti->ti_seq; 256 tcp_rcvseqinit(tp); 257 tp->t_flags |= TF_ACKNOW; 258 if (SEQ_GT(tp->snd_una, tp->iss)) { 259 if (so->so_options & SO_ACCEPTCONN) 260 so->so_state |= SS_CONNAWAITING; 261 soisconnected(so); 262 tp->t_state = TCPS_ESTABLISHED; 263 (void) tcp_reass(tp, (struct tcpiphdr *)0); 264 } else 265 tp->t_state = TCPS_SYN_RECEIVED; 266 goto trimthenstep6; 267 268 trimthenstep6: 269 /* 270 * Advance ti->ti_seq to correspond to first data byte. 271 * If data, trim to stay within window, 272 * dropping FIN if necessary. 273 */ 274 ti->ti_seq++; 275 if (ti->ti_len > tp->rcv_wnd) { 276 todrop = ti->ti_len - tp->rcv_wnd; 277 m_adj(m, -todrop); 278 ti->ti_len = tp->rcv_wnd; 279 ti->ti_flags &= ~TH_FIN; 280 } 281 tp->snd_wl1 = ti->ti_seq - 1; 282 goto step6; 283 } 284 285 /* 286 * States other than LISTEN or SYN_SENT. 287 * First check that at least some bytes of segment are within 288 * receive window. 289 */ 290 if (tp->rcv_wnd == 0) { 291 /* 292 * If window is closed can only take segments at 293 * window edge, and have to drop data and PUSH from 294 * incoming segments. 295 */ 296 if (tp->rcv_nxt != ti->ti_seq) 297 goto dropafterack; 298 if (ti->ti_len > 0) { 299 m_adj(m, ti->ti_len); 300 ti->ti_len = 0; 301 ti->ti_flags &= ~(TH_PUSH|TH_FIN); 302 } 303 } else { 304 /* 305 * If segment begins before rcv_nxt, drop leading 306 * data (and SYN); if nothing left, just ack. 307 */ 308 todrop = tp->rcv_nxt - ti->ti_seq; 309 if (todrop > 0) { 310 if (tiflags & TH_SYN) { 311 tiflags &= ~TH_SYN; 312 ti->ti_flags &= ~TH_SYN; 313 ti->ti_seq++; 314 if (ti->ti_urp > 1) 315 ti->ti_urp--; 316 else 317 tiflags &= ~TH_URG; 318 todrop--; 319 } 320 if (todrop > ti->ti_len) 321 goto dropafterack; 322 m_adj(m, todrop); 323 ti->ti_seq += todrop; 324 ti->ti_len -= todrop; 325 if (ti->ti_urp > todrop) 326 ti->ti_urp -= todrop; 327 else { 328 tiflags &= ~TH_URG; 329 ti->ti_flags &= ~TH_URG; 330 ti->ti_urp = 0; 331 } 332 } 333 /* 334 * If segment ends after window, drop trailing data 335 * (and PUSH and FIN); if nothing left, just ACK. 336 */ 337 todrop = (ti->ti_seq+ti->ti_len) - (tp->rcv_nxt+tp->rcv_wnd); 338 if (todrop > 0) { 339 if (todrop > ti->ti_len) 340 goto dropafterack; 341 m_adj(m, -todrop); 342 ti->ti_len -= todrop; 343 ti->ti_flags &= ~(TH_PUSH|TH_FIN); 344 } 345 } 346 347 /* 348 * If a segment is received on a connection after the 349 * user processes are gone, then RST the other end. 350 */ 351 if (so->so_state & SS_USERGONE) { 352 tcp_close(tp); 353 goto dropwithreset; 354 } 355 356 /* 357 * If the RST bit is set examine the state: 358 * SYN_RECEIVED STATE: 359 * If passive open, return to LISTEN state. 360 * If active open, inform user that connection was refused. 361 * ESTABLISHED, FIN_WAIT_1, FIN_WAIT2, CLOSE_WAIT STATES: 362 * Inform user that connection was reset, and close tcb. 363 * CLOSING, LAST_ACK, TIME_WAIT STATES 364 * Close the tcb. 365 */ 366 if (tiflags&TH_RST) switch (tp->t_state) { 367 368 case TCPS_SYN_RECEIVED: 369 if (inp->inp_socket->so_options & SO_ACCEPTCONN) { 370 /* a miniature tcp_close, but invisible to user */ 371 (void) m_free(dtom(tp->t_template)); 372 (void) m_free(dtom(tp)); 373 inp->inp_ppcb = 0; 374 tp = tcp_newtcpcb(inp); 375 tp->t_state = TCPS_LISTEN; 376 inp->inp_faddr.s_addr = 0; 377 inp->inp_fport = 0; 378 inp->inp_laddr.s_addr = 0; /* not quite right */ 379 goto drop; 380 } 381 tcp_drop(tp, ECONNREFUSED); 382 goto drop; 383 384 case TCPS_ESTABLISHED: 385 case TCPS_FIN_WAIT_1: 386 case TCPS_FIN_WAIT_2: 387 case TCPS_CLOSE_WAIT: 388 tcp_drop(tp, ECONNRESET); 389 goto drop; 390 391 case TCPS_CLOSING: 392 case TCPS_LAST_ACK: 393 case TCPS_TIME_WAIT: 394 tcp_close(tp); 395 goto drop; 396 } 397 398 /* 399 * If a SYN is in the window, then this is an 400 * error and we send an RST and drop the connection. 401 */ 402 if (tiflags & TH_SYN) { 403 tcp_drop(tp, ECONNRESET); 404 goto dropwithreset; 405 } 406 407 /* 408 * If the ACK bit is off we drop the segment and return. 409 */ 410 if ((tiflags & TH_ACK) == 0) 411 goto drop; 412 413 /* 414 * Ack processing. 415 */ 416 switch (tp->t_state) { 417 418 /* 419 * In SYN_RECEIVED state if the ack ACKs our SYN then enter 420 * ESTABLISHED state and continue processing, othewise 421 * send an RST. 422 */ 423 case TCPS_SYN_RECEIVED: 424 if (SEQ_GT(tp->snd_una, ti->ti_ack) || 425 SEQ_GT(ti->ti_ack, tp->snd_max)) 426 goto dropwithreset; 427 tp->snd_una++; /* SYN acked */ 428 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 429 tp->snd_nxt = tp->snd_una; 430 tp->t_timer[TCPT_REXMT] = 0; 431 if (so->so_options & SO_ACCEPTCONN) 432 so->so_state |= SS_CONNAWAITING; 433 soisconnected(so); 434 tp->t_state = TCPS_ESTABLISHED; 435 (void) tcp_reass(tp, (struct tcpiphdr *)0); 436 tp->snd_wl1 = ti->ti_seq - 1; 437 /* fall into ... */ 438 439 /* 440 * In ESTABLISHED state: drop duplicate ACKs; ACK out of range 441 * ACKs. If the ack is in the range 442 * tp->snd_una < ti->ti_ack <= tp->snd_max 443 * then advance tp->snd_una to ti->ti_ack and drop 444 * data from the retransmission queue. If this ACK reflects 445 * more up to date window information we update our window information. 446 */ 447 case TCPS_ESTABLISHED: 448 case TCPS_FIN_WAIT_1: 449 case TCPS_FIN_WAIT_2: 450 case TCPS_CLOSE_WAIT: 451 case TCPS_CLOSING: 452 case TCPS_LAST_ACK: 453 case TCPS_TIME_WAIT: 454 #define ourfinisacked (acked > 0) 455 456 if (SEQ_LEQ(ti->ti_ack, tp->snd_una)) 457 break; 458 if (SEQ_GT(ti->ti_ack, tp->snd_max)) 459 goto dropafterack; 460 acked = ti->ti_ack - tp->snd_una; 461 462 /* 463 * If transmit timer is running and timed sequence 464 * number was acked, update smoothed round trip time. 465 */ 466 if (tp->t_rtt && SEQ_GT(ti->ti_ack, tp->t_rtseq)) { 467 if (tp->t_srtt == 0) 468 tp->t_srtt = tp->t_rtt; 469 else 470 tp->t_srtt = 471 tcp_alpha * tp->t_srtt + 472 (1 - tcp_alpha) * tp->t_rtt; 473 /* printf("rtt %d srtt*100 now %d\n", tp->t_rtt, (int)(tp->t_srtt*100)); */ 474 tp->t_rtt = 0; 475 } 476 477 if (ti->ti_ack == tp->snd_max) 478 tp->t_timer[TCPT_REXMT] = 0; 479 else { 480 TCPT_RANGESET(tp->t_timer[TCPT_REXMT], 481 tcp_beta * tp->t_srtt, TCPTV_MIN, TCPTV_MAX); 482 tp->t_rtt = 1; 483 tp->t_rxtshift = 0; 484 } 485 if (acked > so->so_snd.sb_cc) { 486 sbdrop(&so->so_snd, so->so_snd.sb_cc); 487 tp->snd_wnd -= so->so_snd.sb_cc; 488 } else { 489 sbdrop(&so->so_snd, acked); 490 tp->snd_wnd -= acked; 491 acked = 0; 492 } 493 if (so->so_snd.sb_flags & SB_WAIT) 494 sowwakeup(so); 495 tp->snd_una = ti->ti_ack; 496 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 497 tp->snd_nxt = tp->snd_una; 498 499 switch (tp->t_state) { 500 501 /* 502 * In FIN_WAIT_1 STATE in addition to the processing 503 * for the ESTABLISHED state if our FIN is now acknowledged 504 * then enter FIN_WAIT_2. 505 */ 506 case TCPS_FIN_WAIT_1: 507 if (ourfinisacked) { 508 /* 509 * If we can't receive any more 510 * data, then closing user can proceed. 511 */ 512 if (so->so_state & SS_CANTRCVMORE) 513 soisdisconnected(so); 514 tp->t_state = TCPS_FIN_WAIT_2; 515 } 516 break; 517 518 /* 519 * In CLOSING STATE in addition to the processing for 520 * the ESTABLISHED state if the ACK acknowledges our FIN 521 * then enter the TIME-WAIT state, otherwise ignore 522 * the segment. 523 */ 524 case TCPS_CLOSING: 525 if (ourfinisacked) { 526 tp->t_state = TCPS_TIME_WAIT; 527 tcp_canceltimers(tp); 528 tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; 529 soisdisconnected(so); 530 } 531 break; 532 533 /* 534 * The only thing that can arrive in LAST_ACK state 535 * is an acknowledgment of our FIN. If our FIN is now 536 * acknowledged, delete the TCB, enter the closed state 537 * and return. 538 */ 539 case TCPS_LAST_ACK: 540 if (ourfinisacked) 541 tcp_close(tp); 542 goto drop; 543 544 /* 545 * In TIME_WAIT state the only thing that should arrive 546 * is a retransmission of the remote FIN. Acknowledge 547 * it and restart the finack timer. 548 */ 549 case TCPS_TIME_WAIT: 550 tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; 551 goto dropafterack; 552 } 553 #undef ourfinisacked 554 } 555 556 step6: 557 /* 558 * Update window information. 559 */ 560 if (SEQ_LT(tp->snd_wl1, ti->ti_seq) || tp->snd_wl1 == ti->ti_seq && 561 (SEQ_LT(tp->snd_wl2, ti->ti_ack) || 562 tp->snd_wl2 == ti->ti_ack && ti->ti_win > tp->snd_wnd)) { 563 tp->snd_wnd = ti->ti_win; 564 tp->snd_wl1 = ti->ti_seq; 565 tp->snd_wl2 = ti->ti_ack; 566 if (tp->snd_wnd > 0) 567 tp->t_timer[TCPT_PERSIST] = 0; 568 } 569 570 /* 571 * Process segments with URG. 572 */ 573 if ((tiflags & TH_URG) && TCPS_HAVERCVDFIN(tp->t_state) == 0) { 574 /* 575 * If this segment advances the known urgent pointer, 576 * then mark the data stream. This should not happen 577 * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since 578 * a FIN has been received from the remote side. 579 * In these states we ignore the URG. 580 */ 581 if (SEQ_GT(ti->ti_seq+ti->ti_urp, tp->rcv_up)) { 582 tp->rcv_up = ti->ti_seq + ti->ti_urp; 583 so->so_oobmark = so->so_rcv.sb_cc + 584 (tp->rcv_up - tp->rcv_nxt) - 1; 585 if (so->so_oobmark == 0) 586 so->so_state |= SS_RCVATMARK; 587 #ifdef TCPTRUEOOB 588 if ((tp->t_flags & TF_DOOOB) == 0) 589 #endif 590 sohasoutofband(so); 591 tp->t_oobflags &= ~TCPOOB_HAVEDATA; 592 } 593 /* 594 * Remove out of band data so doesn't get presented to user. 595 * This can happen independent of advancing the URG pointer, 596 * but if two URG's are pending at once, some out-of-band 597 * data may creep in... ick. 598 */ 599 if (ti->ti_urp <= ti->ti_len) { 600 tcp_pulloutofband(so, ti); 601 } 602 } 603 604 /* 605 * Process the segment text, merging it into the TCP sequencing queue, 606 * and arranging for acknowledgment of receipt if necessary. 607 * This process logically involves adjusting tp->rcv_wnd as data 608 * is presented to the user (this happens in tcp_usrreq.c, 609 * case PRU_RCVD). If a FIN has already been received on this 610 * connection then we just ignore the text. 611 */ 612 if ((ti->ti_len || (tiflags&TH_FIN)) && 613 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 614 tiflags = tcp_reass(tp, ti); 615 if (tcpnodelack == 0) 616 tp->t_flags |= TF_DELACK; 617 else 618 tp->t_flags |= TF_ACKNOW; 619 } else { 620 m_freem(m); 621 tiflags &= ~TH_FIN; 622 } 623 624 /* 625 * If FIN is received ACK the FIN and let the user know 626 * that the connection is closing. 627 */ 628 if (tiflags & TH_FIN) { 629 if (TCPS_HAVERCVDFIN(tp->t_state) == 0) { 630 socantrcvmore(so); 631 tp->t_flags |= TF_ACKNOW; 632 tp->rcv_nxt++; 633 } 634 switch (tp->t_state) { 635 636 /* 637 * In SYN_RECEIVED and ESTABLISHED STATES 638 * enter the CLOSE_WAIT state. 639 */ 640 case TCPS_SYN_RECEIVED: 641 case TCPS_ESTABLISHED: 642 tp->t_state = TCPS_CLOSE_WAIT; 643 break; 644 645 /* 646 * If still in FIN_WAIT_1 STATE FIN has not been acked so 647 * enter the CLOSING state. 648 */ 649 case TCPS_FIN_WAIT_1: 650 tp->t_state = TCPS_CLOSING; 651 break; 652 653 /* 654 * In FIN_WAIT_2 state enter the TIME_WAIT state, 655 * starting the time-wait timer, turning off the other 656 * standard timers. 657 */ 658 case TCPS_FIN_WAIT_2: 659 tp->t_state = TCPS_TIME_WAIT; 660 tcp_canceltimers(tp); 661 tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; 662 soisdisconnected(so); 663 break; 664 665 /* 666 * In TIME_WAIT state restart the 2 MSL time_wait timer. 667 */ 668 case TCPS_TIME_WAIT: 669 tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; 670 break; 671 } 672 } 673 if (so->so_options & SO_DEBUG) 674 tcp_trace(TA_INPUT, ostate, tp, &tcp_saveti, 0); 675 676 /* 677 * Return any desired output. 678 */ 679 (void) tcp_output(tp); 680 return; 681 682 dropafterack: 683 /* 684 * Generate an ACK dropping incoming segment. 685 * Make ACK reflect our state. 686 */ 687 if (tiflags & TH_RST) 688 goto drop; 689 tcp_respond(tp, ti, tp->rcv_nxt, tp->snd_nxt, TH_ACK); 690 return; 691 692 dropwithreset: 693 if (om) 694 (void) m_free(om); 695 /* 696 * Generate a RST, dropping incoming segment. 697 * Make ACK acceptable to originator of segment. 698 */ 699 if (tiflags & TH_RST) 700 goto drop; 701 if (tiflags & TH_ACK) 702 tcp_respond(tp, ti, (tcp_seq)0, ti->ti_ack, TH_RST); 703 else { 704 if (tiflags & TH_SYN) 705 ti->ti_len++; 706 tcp_respond(tp, ti, ti->ti_seq+ti->ti_len, (tcp_seq)0, TH_RST|TH_ACK); 707 } 708 return; 709 710 drop: 711 /* 712 * Drop space held by incoming segment and return. 713 */ 714 m_freem(m); 715 return; 716 } 717 718 tcp_dooptions(tp, om) 719 struct tcpcb *tp; 720 struct mbuf *om; 721 { 722 register u_char *cp; 723 int opt, optlen, cnt; 724 725 cp = mtod(om, u_char *); 726 cnt = om->m_len; 727 for (; cnt > 0; cnt -= optlen, cp += optlen) { 728 opt = cp[0]; 729 if (opt == TCPOPT_EOL) 730 break; 731 if (opt == TCPOPT_NOP) 732 optlen = 1; 733 else 734 optlen = cp[1]; 735 switch (opt) { 736 737 default: 738 break; 739 740 case TCPOPT_MAXSEG: 741 if (optlen != 4) 742 continue; 743 tp->t_maxseg = *(u_short *)(cp + 2); 744 #if vax 745 tp->t_maxseg = ntohs((u_short)tp->t_maxseg); 746 #endif 747 break; 748 749 #ifdef TCPTRUEOOB 750 case TCPOPT_WILLOOB: 751 tp->t_flags |= TF_DOOOB; 752 printf("tp %x dooob\n", tp); 753 break; 754 755 case TCPOPT_OOBDATA: { 756 int seq; 757 register struct socket *so = tp->t_inpcb->inp_socket; 758 tcp_seq mark; 759 760 if (optlen != 8) 761 continue; 762 seq = cp[2]; 763 if (seq < tp->t_iobseq) 764 seq += 256; 765 printf("oobdata cp[2] %d iobseq %d seq %d\n", cp[2], tp->t_iobseq, seq); 766 if (seq - tp->t_iobseq > 128) { 767 printf("bad seq\n"); 768 tp->t_oobflags |= TCPOOB_OWEACK; 769 break; 770 } 771 tp->t_iobseq = cp[2]; 772 tp->t_iobc = cp[3]; 773 mark = *(tcp_seq *)(cp + 4); 774 #if vax 775 mark = ntohl(mark); 776 #endif 777 so->so_oobmark = so->so_rcv.sb_cc + (mark-tp->rcv_nxt); 778 if (so->so_oobmark == 0) 779 so->so_state |= SS_RCVATMARK; 780 printf("take oob data %x input iobseq now %x\n", tp->t_iobc, tp->t_iobseq); 781 sohasoutofband(so); 782 break; 783 } 784 785 case TCPOPT_OOBACK: { 786 int seq; 787 788 if (optlen != 4) 789 continue; 790 if (tp->t_oobseq != cp[2]) { 791 printf("wrong ack\n"); 792 break; 793 } 794 printf("take oob ack %x and cancel rexmt\n", cp[2]); 795 tp->t_oobflags &= ~TCPOOB_NEEDACK; 796 tp->t_timer[TCPT_OOBREXMT] = 0; 797 break; 798 } 799 #endif TCPTRUEOOB 800 } 801 } 802 (void) m_free(om); 803 } 804 805 /* 806 * Pull out of band byte out of a segment so 807 * it doesn't appear in the user's data queue. 808 * It is still reflected in the segment length for 809 * sequencing purposes. 810 */ 811 tcp_pulloutofband(so, ti) 812 struct socket *so; 813 struct tcpiphdr *ti; 814 { 815 register struct mbuf *m; 816 int cnt = ti->ti_urp - 1; 817 818 m = dtom(ti); 819 while (cnt >= 0) { 820 if (m->m_len > cnt) { 821 char *cp = mtod(m, caddr_t) + cnt; 822 struct tcpcb *tp = sototcpcb(so); 823 824 tp->t_iobc = *cp; 825 tp->t_oobflags |= TCPOOB_HAVEDATA; 826 bcopy(cp+1, cp, (unsigned)(m->m_len - cnt - 1)); 827 m->m_len--; 828 return; 829 } 830 cnt -= m->m_len; 831 m = m->m_next; 832 if (m == 0) 833 break; 834 } 835 panic("tcp_pulloutofband"); 836 } 837 838 /* 839 * Insert segment ti into reassembly queue of tcp with 840 * control block tp. Return TH_FIN if reassembly now includes 841 * a segment with FIN. 842 */ 843 tcp_reass(tp, ti) 844 register struct tcpcb *tp; 845 register struct tcpiphdr *ti; 846 { 847 register struct tcpiphdr *q; 848 struct socket *so = tp->t_inpcb->inp_socket; 849 struct mbuf *m; 850 int flags; 851 COUNT(TCP_REASS); 852 853 /* 854 * Call with ti==0 after become established to 855 * force pre-ESTABLISHED data up to user socket. 856 */ 857 if (ti == 0) 858 goto present; 859 860 /* 861 * Find a segment which begins after this one does. 862 */ 863 for (q = tp->seg_next; q != (struct tcpiphdr *)tp; 864 q = (struct tcpiphdr *)q->ti_next) 865 if (SEQ_GT(q->ti_seq, ti->ti_seq)) 866 break; 867 868 /* 869 * If there is a preceding segment, it may provide some of 870 * our data already. If so, drop the data from the incoming 871 * segment. If it provides all of our data, drop us. 872 */ 873 if ((struct tcpiphdr *)q->ti_prev != (struct tcpiphdr *)tp) { 874 register int i; 875 q = (struct tcpiphdr *)q->ti_prev; 876 /* conversion to int (in i) handles seq wraparound */ 877 i = q->ti_seq + q->ti_len - ti->ti_seq; 878 if (i > 0) { 879 if (i >= ti->ti_len) 880 goto drop; 881 m_adj(dtom(tp), i); 882 ti->ti_len -= i; 883 ti->ti_seq += i; 884 } 885 q = (struct tcpiphdr *)(q->ti_next); 886 } 887 888 /* 889 * While we overlap succeeding segments trim them or, 890 * if they are completely covered, dequeue them. 891 */ 892 while (q != (struct tcpiphdr *)tp) { 893 register int i = (ti->ti_seq + ti->ti_len) - q->ti_seq; 894 if (i <= 0) 895 break; 896 if (i < q->ti_len) { 897 q->ti_seq += i; 898 q->ti_len -= i; 899 m_adj(dtom(q), i); 900 break; 901 } 902 q = (struct tcpiphdr *)q->ti_next; 903 m = dtom(q->ti_prev); 904 remque(q->ti_prev); 905 m_freem(m); 906 } 907 908 /* 909 * Stick new segment in its place. 910 */ 911 insque(ti, q->ti_prev); 912 913 present: 914 /* 915 * Present data to user, advancing rcv_nxt through 916 * completed sequence space. 917 */ 918 if (TCPS_HAVERCVDSYN(tp->t_state) == 0) 919 return (0); 920 ti = tp->seg_next; 921 if (ti == (struct tcpiphdr *)tp || ti->ti_seq != tp->rcv_nxt) 922 return (0); 923 if (tp->t_state == TCPS_SYN_RECEIVED && ti->ti_len) 924 return (0); 925 do { 926 tp->rcv_nxt += ti->ti_len; 927 flags = ti->ti_flags & TH_FIN; 928 remque(ti); 929 m = dtom(ti); 930 ti = (struct tcpiphdr *)ti->ti_next; 931 if (so->so_state & SS_CANTRCVMORE) 932 m_freem(m); 933 else 934 sbappend(&so->so_rcv, m); 935 } while (ti != (struct tcpiphdr *)tp && ti->ti_seq == tp->rcv_nxt); 936 sorwakeup(so); 937 return (flags); 938 drop: 939 m_freem(dtom(ti)); 940 return (0); 941 } 942