1 /* 2 * Copyright (c) 1987, 1989, 1992 Regents of the University of California. 3 * All rights reserved. 4 * 5 * %sccs.include.redist.c% 6 * 7 * @(#)if_sl.c 7.29 (Berkeley) 07/06/92 8 */ 9 10 /* 11 * Serial Line interface 12 * 13 * Rick Adams 14 * Center for Seismic Studies 15 * 1300 N 17th Street, Suite 1450 16 * Arlington, Virginia 22209 17 * (703)276-7900 18 * rick@seismo.ARPA 19 * seismo!rick 20 * 21 * Pounded on heavily by Chris Torek (chris@mimsy.umd.edu, umcp-cs!chris). 22 * N.B.: this belongs in netinet, not net, the way it stands now. 23 * Should have a link-layer type designation, but wouldn't be 24 * backwards-compatible. 25 * 26 * Converted to 4.3BSD Beta by Chris Torek. 27 * Other changes made at Berkeley, based in part on code by Kirk Smith. 28 * W. Jolitz added slip abort. 29 * 30 * Hacked almost beyond recognition by Van Jacobson (van@helios.ee.lbl.gov). 31 * Added priority queuing for "interactive" traffic; hooks for TCP 32 * header compression; ICMP filtering (at 2400 baud, some cretin 33 * pinging you can use up all your bandwidth). Made low clist behavior 34 * more robust and slightly less likely to hang serial line. 35 * Sped up a bunch of things. 36 * 37 * Note that splimp() is used throughout to block both (tty) input 38 * interrupts and network activity; thus, splimp must be >= spltty. 39 */ 40 41 #include "sl.h" 42 #if NSL > 0 43 44 #include "param.h" 45 #include "proc.h" 46 #include "mbuf.h" 47 #include "buf.h" 48 #include "dkstat.h" 49 #include "socket.h" 50 #include "ioctl.h" 51 #include "file.h" 52 #include "tty.h" 53 #include "kernel.h" 54 #include "conf.h" 55 #include "machine/cpu.h" 56 57 #include "if.h" 58 #include "if_types.h" 59 #include "netisr.h" 60 #include "route.h" 61 62 #if INET 63 #include "netinet/in.h" 64 #include "netinet/in_systm.h" 65 #include "netinet/in_var.h" 66 #include "netinet/ip.h" 67 #else 68 Huh? Slip without inet? 69 #endif 70 71 #include "slcompress.h" 72 #include "if_slvar.h" 73 74 /* 75 * SLMAX is a hard limit on input packet size. To simplify the code 76 * and improve performance, we require that packets fit in an mbuf 77 * cluster, and if we get a compressed packet, there's enough extra 78 * room to expand the header into a max length tcp/ip header (128 79 * bytes). So, SLMAX can be at most 80 * MCLBYTES - 128 81 * 82 * SLMTU is a hard limit on output packet size. To insure good 83 * interactive response, SLMTU wants to be the smallest size that 84 * amortizes the header cost. (Remember that even with 85 * type-of-service queuing, we have to wait for any in-progress 86 * packet to finish. I.e., we wait, on the average, 1/2 * mtu / 87 * cps, where cps is the line speed in characters per second. 88 * E.g., 533ms wait for a 1024 byte MTU on a 9600 baud line. The 89 * average compressed header size is 6-8 bytes so any MTU > 90 90 * bytes will give us 90% of the line bandwidth. A 100ms wait is 91 * tolerable (500ms is not), so want an MTU around 296. (Since TCP 92 * will send 256 byte segments (to allow for 40 byte headers), the 93 * typical packet size on the wire will be around 260 bytes). In 94 * 4.3tahoe+ systems, we can set an MTU in a route so we do that & 95 * leave the interface MTU relatively high (so we don't IP fragment 96 * when acting as a gateway to someone using a stupid MTU). 97 * 98 * Similar considerations apply to SLIP_HIWAT: It's the amount of 99 * data that will be queued 'downstream' of us (i.e., in clists 100 * waiting to be picked up by the tty output interrupt). If we 101 * queue a lot of data downstream, it's immune to our t.o.s. queuing. 102 * E.g., if SLIP_HIWAT is 1024, the interactive traffic in mixed 103 * telnet/ftp will see a 1 sec wait, independent of the mtu (the 104 * wait is dependent on the ftp window size but that's typically 105 * 1k - 4k). So, we want SLIP_HIWAT just big enough to amortize 106 * the cost (in idle time on the wire) of the tty driver running 107 * off the end of its clists & having to call back slstart for a 108 * new packet. For a tty interface with any buffering at all, this 109 * cost will be zero. Even with a totally brain dead interface (like 110 * the one on a typical workstation), the cost will be <= 1 character 111 * time. So, setting SLIP_HIWAT to ~100 guarantees that we'll lose 112 * at most 1% while maintaining good interactive response. 113 */ 114 #define BUFOFFSET 128 115 #define SLMAX (MCLBYTES - BUFOFFSET) 116 #define SLBUFSIZE (SLMAX + BUFOFFSET) 117 #define SLMTU 296 118 #define SLIP_HIWAT roundup(50,CBSIZE) 119 #define CLISTRESERVE 1024 /* Can't let clists get too low */ 120 121 /* 122 * SLIP ABORT ESCAPE MECHANISM: 123 * (inspired by HAYES modem escape arrangement) 124 * 1sec escape 1sec escape 1sec escape { 1sec escape 1sec escape } 125 * within window time signals a "soft" exit from slip mode by remote end 126 * if the IFF_DEBUG flag is on. 127 */ 128 #define ABT_ESC '\033' /* can't be t_intr - distant host must know it*/ 129 #define ABT_IDLE 1 /* in seconds - idle before an escape */ 130 #define ABT_COUNT 3 /* count of escapes for abort */ 131 #define ABT_WINDOW (ABT_COUNT*2+2) /* in seconds - time to count */ 132 133 struct sl_softc sl_softc[NSL]; 134 135 #define FRAME_END 0xc0 /* Frame End */ 136 #define FRAME_ESCAPE 0xdb /* Frame Esc */ 137 #define TRANS_FRAME_END 0xdc /* transposed frame end */ 138 #define TRANS_FRAME_ESCAPE 0xdd /* transposed frame esc */ 139 140 #define t_sc T_LINEP 141 142 int sloutput(), slioctl(), ttrstrt(); 143 extern struct timeval time; 144 145 /* 146 * Called from boot code to establish sl interfaces. 147 */ 148 slattach() 149 { 150 register struct sl_softc *sc; 151 register int i = 0; 152 153 for (sc = sl_softc; i < NSL; sc++) { 154 sc->sc_if.if_name = "sl"; 155 sc->sc_if.if_next = NULL; 156 sc->sc_if.if_unit = i++; 157 sc->sc_if.if_mtu = SLMTU; 158 #ifdef MULTICAST 159 sc->sc_if.if_flags = 160 IFF_POINTOPOINT | SC_AUTOCOMP | IFF_MULTICAST; 161 #else 162 sc->sc_if.if_flags = IFF_POINTOPOINT | SC_AUTOCOMP; 163 #endif 164 sc->sc_if.if_type = IFT_SLIP; 165 sc->sc_if.if_ioctl = slioctl; 166 sc->sc_if.if_output = sloutput; 167 sc->sc_if.if_snd.ifq_maxlen = 50; 168 sc->sc_fastq.ifq_maxlen = 32; 169 if_attach(&sc->sc_if); 170 } 171 } 172 173 static int 174 slinit(sc) 175 register struct sl_softc *sc; 176 { 177 register caddr_t p; 178 179 if (sc->sc_ep == (u_char *) 0) { 180 MCLALLOC(p, M_WAIT); 181 if (p) 182 sc->sc_ep = (u_char *)p + SLBUFSIZE; 183 else { 184 printf("sl%d: can't allocate buffer\n", sc - sl_softc); 185 sc->sc_if.if_flags &= ~IFF_UP; 186 return (0); 187 } 188 } 189 sc->sc_buf = sc->sc_ep - SLMAX; 190 sc->sc_mp = sc->sc_buf; 191 sl_compress_init(&sc->sc_comp); 192 return (1); 193 } 194 195 /* 196 * Line specific open routine. 197 * Attach the given tty to the first available sl unit. 198 */ 199 /* ARGSUSED */ 200 slopen(dev, tp) 201 dev_t dev; 202 register struct tty *tp; 203 { 204 struct proc *p = curproc; /* XXX */ 205 register struct sl_softc *sc; 206 register int nsl; 207 int error; 208 209 if (error = suser(p->p_ucred, &p->p_acflag)) 210 return (error); 211 212 if (tp->t_line == SLIPDISC) 213 return (0); 214 215 for (nsl = NSL, sc = sl_softc; --nsl >= 0; sc++) 216 if (sc->sc_ttyp == NULL) { 217 if (slinit(sc) == 0) 218 return (ENOBUFS); 219 tp->t_sc = (caddr_t)sc; 220 sc->sc_ttyp = tp; 221 sc->sc_if.if_baudrate = tp->t_ospeed; 222 ttyflush(tp, FREAD | FWRITE); 223 return (0); 224 } 225 return (ENXIO); 226 } 227 228 /* 229 * Line specific close routine. 230 * Detach the tty from the sl unit. 231 * Mimics part of ttyclose(). 232 */ 233 slclose(tp) 234 struct tty *tp; 235 { 236 register struct sl_softc *sc; 237 int s; 238 239 ttywflush(tp); 240 s = splimp(); /* actually, max(spltty, splnet) */ 241 tp->t_line = 0; 242 sc = (struct sl_softc *)tp->t_sc; 243 if (sc != NULL) { 244 if_down(&sc->sc_if); 245 sc->sc_ttyp = NULL; 246 tp->t_sc = NULL; 247 MCLFREE((caddr_t)(sc->sc_ep - SLBUFSIZE)); 248 sc->sc_ep = 0; 249 sc->sc_mp = 0; 250 sc->sc_buf = 0; 251 } 252 splx(s); 253 } 254 255 /* 256 * Line specific (tty) ioctl routine. 257 * Provide a way to get the sl unit number. 258 */ 259 /* ARGSUSED */ 260 sltioctl(tp, cmd, data, flag) 261 struct tty *tp; 262 int cmd; 263 caddr_t data; 264 int flag; 265 { 266 struct sl_softc *sc = (struct sl_softc *)tp->t_sc; 267 int s; 268 269 switch (cmd) { 270 case SLIOCGUNIT: 271 *(int *)data = sc->sc_if.if_unit; 272 break; 273 274 default: 275 return (-1); 276 } 277 return (0); 278 } 279 280 /* 281 * Queue a packet. Start transmission if not active. 282 */ 283 sloutput(ifp, m, dst) 284 struct ifnet *ifp; 285 register struct mbuf *m; 286 struct sockaddr *dst; 287 { 288 register struct sl_softc *sc = &sl_softc[ifp->if_unit]; 289 register struct ip *ip; 290 register struct ifqueue *ifq; 291 register int p; 292 int s; 293 294 /* 295 * `Cannot happen' (see slioctl). Someday we will extend 296 * the line protocol to support other address families. 297 */ 298 if (dst->sa_family != AF_INET) { 299 printf("sl%d: af%d not supported\n", sc->sc_if.if_unit, 300 dst->sa_family); 301 m_freem(m); 302 sc->sc_if.if_noproto++; 303 return (EAFNOSUPPORT); 304 } 305 306 if (sc->sc_ttyp == NULL) { 307 m_freem(m); 308 return (ENETDOWN); /* sort of */ 309 } 310 if ((sc->sc_ttyp->t_state & TS_CARR_ON) == 0) { 311 m_freem(m); 312 return (EHOSTUNREACH); 313 } 314 ifq = &sc->sc_if.if_snd; 315 ip = mtod(m, struct ip *); 316 if (ip->ip_tos & IPTOS_LOWDELAY) { 317 ifq = &sc->sc_fastq; 318 p = 1; 319 } else 320 p = 0; 321 if (ip->ip_p == IPPROTO_TCP) { 322 if (sc->sc_if.if_flags & SC_COMPRESS) { 323 /* 324 * The last parameter turns off connection id 325 * compression for background traffic: Since 326 * fastq traffic can jump ahead of the background 327 * traffic, we don't know what order packets will 328 * go on the line. 329 */ 330 p = sl_compress_tcp(m, ip, &sc->sc_comp, p); 331 *mtod(m, u_char *) |= p; 332 } 333 } else if (sc->sc_if.if_flags & SC_NOICMP && ip->ip_p == IPPROTO_ICMP) { 334 m_freem(m); 335 return (ENETRESET); /* XXX ? */ 336 } 337 s = splimp(); 338 if (IF_QFULL(ifq)) { 339 IF_DROP(ifq); 340 m_freem(m); 341 splx(s); 342 sc->sc_if.if_oerrors++; 343 return (ENOBUFS); 344 } 345 IF_ENQUEUE(ifq, m); 346 sc->sc_if.if_lastchange = time; 347 if (sc->sc_ttyp->t_outq.c_cc == 0) 348 slstart(sc->sc_ttyp); 349 splx(s); 350 return (0); 351 } 352 353 /* 354 * Start output on interface. Get another datagram 355 * to send from the interface queue and map it to 356 * the interface before starting output. 357 */ 358 slstart(tp) 359 register struct tty *tp; 360 { 361 register struct sl_softc *sc = (struct sl_softc *)tp->t_sc; 362 register struct mbuf *m; 363 register u_char *cp; 364 int s; 365 struct mbuf *m2; 366 extern int cfreecount; 367 368 for (;;) { 369 /* 370 * If there is more in the output queue, just send it now. 371 * We are being called in lieu of ttstart and must do what 372 * it would. 373 */ 374 if (tp->t_outq.c_cc != 0) { 375 (*tp->t_oproc)(tp); 376 if (tp->t_outq.c_cc > SLIP_HIWAT) 377 return; 378 } 379 /* 380 * This happens briefly when the line shuts down. 381 */ 382 if (sc == NULL) 383 return; 384 385 /* 386 * Get a packet and send it to the interface. 387 */ 388 s = splimp(); 389 IF_DEQUEUE(&sc->sc_fastq, m); 390 if (m) 391 sc->sc_if.if_omcasts++; /* XXX */ 392 else 393 IF_DEQUEUE(&sc->sc_if.if_snd, m); 394 splx(s); 395 if (m == NULL) 396 return; 397 sc->sc_if.if_lastchange = time; 398 399 /* 400 * If system is getting low on clists, just flush our 401 * output queue (if the stuff was important, it'll get 402 * retransmitted). 403 */ 404 if (cfreecount < CLISTRESERVE + SLMTU) { 405 m_freem(m); 406 sc->sc_if.if_collisions++; 407 continue; 408 } 409 /* 410 * The extra FRAME_END will start up a new packet, and thus 411 * will flush any accumulated garbage. We do this whenever 412 * the line may have been idle for some time. 413 */ 414 if (tp->t_outq.c_cc == 0) { 415 ++sc->sc_if.if_obytes; 416 (void) putc(FRAME_END, &tp->t_outq); 417 } 418 419 while (m) { 420 register u_char *ep; 421 422 cp = mtod(m, u_char *); ep = cp + m->m_len; 423 while (cp < ep) { 424 /* 425 * Find out how many bytes in the string we can 426 * handle without doing something special. 427 */ 428 register u_char *bp = cp; 429 430 while (cp < ep) { 431 switch (*cp++) { 432 case FRAME_ESCAPE: 433 case FRAME_END: 434 --cp; 435 goto out; 436 } 437 } 438 out: 439 if (cp > bp) { 440 /* 441 * Put n characters at once 442 * into the tty output queue. 443 */ 444 if (b_to_q((char *)bp, cp - bp, &tp->t_outq)) 445 break; 446 sc->sc_if.if_obytes += cp - bp; 447 } 448 /* 449 * If there are characters left in the mbuf, 450 * the first one must be special.. 451 * Put it out in a different form. 452 */ 453 if (cp < ep) { 454 if (putc(FRAME_ESCAPE, &tp->t_outq)) 455 break; 456 if (putc(*cp++ == FRAME_ESCAPE ? 457 TRANS_FRAME_ESCAPE : TRANS_FRAME_END, 458 &tp->t_outq)) { 459 (void) unputc(&tp->t_outq); 460 break; 461 } 462 sc->sc_if.if_obytes += 2; 463 } 464 } 465 MFREE(m, m2); 466 m = m2; 467 } 468 469 if (putc(FRAME_END, &tp->t_outq)) { 470 /* 471 * Not enough room. Remove a char to make room 472 * and end the packet normally. 473 * If you get many collisions (more than one or two 474 * a day) you probably do not have enough clists 475 * and you should increase "nclist" in param.c. 476 */ 477 (void) unputc(&tp->t_outq); 478 (void) putc(FRAME_END, &tp->t_outq); 479 sc->sc_if.if_collisions++; 480 } else { 481 ++sc->sc_if.if_obytes; 482 sc->sc_if.if_opackets++; 483 } 484 } 485 } 486 487 /* 488 * Copy data buffer to mbuf chain; add ifnet pointer. 489 */ 490 static struct mbuf * 491 sl_btom(sc, len) 492 register struct sl_softc *sc; 493 register int len; 494 { 495 register struct mbuf *m; 496 497 MGETHDR(m, M_DONTWAIT, MT_DATA); 498 if (m == NULL) 499 return (NULL); 500 501 /* 502 * If we have more than MHLEN bytes, it's cheaper to 503 * queue the cluster we just filled & allocate a new one 504 * for the input buffer. Otherwise, fill the mbuf we 505 * allocated above. Note that code in the input routine 506 * guarantees that packet will fit in a cluster. 507 */ 508 if (len >= MHLEN) { 509 MCLGET(m, M_DONTWAIT); 510 if ((m->m_flags & M_EXT) == 0) { 511 /* 512 * we couldn't get a cluster - if memory's this 513 * low, it's time to start dropping packets. 514 */ 515 (void) m_free(m); 516 return (NULL); 517 } 518 sc->sc_ep = mtod(m, u_char *) + SLBUFSIZE; 519 m->m_data = (caddr_t)sc->sc_buf; 520 m->m_ext.ext_buf = (caddr_t)((int)sc->sc_buf &~ MCLOFSET); 521 } else 522 bcopy((caddr_t)sc->sc_buf, mtod(m, caddr_t), len); 523 524 m->m_len = len; 525 m->m_pkthdr.len = len; 526 m->m_pkthdr.rcvif = &sc->sc_if; 527 return (m); 528 } 529 530 /* 531 * tty interface receiver interrupt. 532 */ 533 slinput(c, tp) 534 register int c; 535 register struct tty *tp; 536 { 537 register struct sl_softc *sc; 538 register struct mbuf *m; 539 register int len; 540 int s; 541 542 tk_nin++; 543 sc = (struct sl_softc *)tp->t_sc; 544 if (sc == NULL) 545 return; 546 if (!(tp->t_state&TS_CARR_ON)) /* XXX */ 547 return; 548 549 ++sc->sc_if.if_ibytes; 550 c &= 0xff; /* XXX */ 551 552 #ifdef ABT_ESC 553 if (sc->sc_if.if_flags & IFF_DEBUG) { 554 if (c == ABT_ESC) { 555 /* 556 * If we have a previous abort, see whether 557 * this one is within the time limit. 558 */ 559 if (sc->sc_abortcount && 560 time.tv_sec >= sc->sc_starttime + ABT_WINDOW) 561 sc->sc_abortcount = 0; 562 /* 563 * If we see an abort after "idle" time, count it; 564 * record when the first abort escape arrived. 565 */ 566 if (time.tv_sec >= sc->sc_lasttime + ABT_IDLE) { 567 if (++sc->sc_abortcount == 1) 568 sc->sc_starttime = time.tv_sec; 569 if (sc->sc_abortcount >= ABT_COUNT) { 570 slclose(tp); 571 return; 572 } 573 } 574 } else 575 sc->sc_abortcount = 0; 576 sc->sc_lasttime = time.tv_sec; 577 } 578 #endif 579 580 switch (c) { 581 582 case TRANS_FRAME_ESCAPE: 583 if (sc->sc_escape) 584 c = FRAME_ESCAPE; 585 break; 586 587 case TRANS_FRAME_END: 588 if (sc->sc_escape) 589 c = FRAME_END; 590 break; 591 592 case FRAME_ESCAPE: 593 sc->sc_escape = 1; 594 return; 595 596 case FRAME_END: 597 len = sc->sc_mp - sc->sc_buf; 598 if (len < 3) 599 /* less than min length packet - ignore */ 600 goto newpack; 601 602 if ((c = (*sc->sc_buf & 0xf0)) != (IPVERSION << 4)) { 603 if (c & 0x80) 604 c = TYPE_COMPRESSED_TCP; 605 else if (c == TYPE_UNCOMPRESSED_TCP) 606 *sc->sc_buf &= 0x4f; /* XXX */ 607 /* 608 * We've got something that's not an IP packet. 609 * If compression is enabled, try to decompress it. 610 * Otherwise, if `auto-enable' compression is on and 611 * it's a reasonable packet, decompress it and then 612 * enable compression. Otherwise, drop it. 613 */ 614 if (sc->sc_if.if_flags & SC_COMPRESS) { 615 len = sl_uncompress_tcp(&sc->sc_buf, len, 616 (u_int)c, &sc->sc_comp); 617 if (len <= 0) 618 goto error; 619 } else if ((sc->sc_if.if_flags & SC_AUTOCOMP) && 620 c == TYPE_UNCOMPRESSED_TCP && len >= 40) { 621 len = sl_uncompress_tcp(&sc->sc_buf, len, 622 (u_int)c, &sc->sc_comp); 623 if (len <= 0) 624 goto error; 625 sc->sc_if.if_flags |= SC_COMPRESS; 626 } else 627 goto error; 628 } 629 m = sl_btom(sc, len); 630 if (m == NULL) 631 goto error; 632 633 sc->sc_if.if_ipackets++; 634 sc->sc_if.if_lastchange = time; 635 s = splimp(); 636 if (IF_QFULL(&ipintrq)) { 637 IF_DROP(&ipintrq); 638 sc->sc_if.if_ierrors++; 639 sc->sc_if.if_iqdrops++; 640 m_freem(m); 641 } else { 642 IF_ENQUEUE(&ipintrq, m); 643 schednetisr(NETISR_IP); 644 } 645 splx(s); 646 goto newpack; 647 } 648 if (sc->sc_mp < sc->sc_ep) { 649 *sc->sc_mp++ = c; 650 sc->sc_escape = 0; 651 return; 652 } 653 error: 654 sc->sc_if.if_ierrors++; 655 newpack: 656 sc->sc_mp = sc->sc_buf = sc->sc_ep - SLMAX; 657 sc->sc_escape = 0; 658 } 659 660 /* 661 * Process an ioctl request. 662 */ 663 slioctl(ifp, cmd, data) 664 register struct ifnet *ifp; 665 int cmd; 666 caddr_t data; 667 { 668 register struct ifaddr *ifa = (struct ifaddr *)data; 669 #ifdef MULTICAST 670 register struct ifreq *ifr; 671 #endif 672 register int s = splimp(), error = 0; 673 674 switch (cmd) { 675 676 case SIOCSIFADDR: 677 if (ifa->ifa_addr->sa_family == AF_INET) 678 ifp->if_flags |= IFF_UP; 679 else 680 error = EAFNOSUPPORT; 681 break; 682 683 case SIOCSIFDSTADDR: 684 if (ifa->ifa_addr->sa_family != AF_INET) 685 error = EAFNOSUPPORT; 686 break; 687 688 #ifdef MULTICAST 689 case SIOCADDMULTI: 690 case SIOCDELMULTI: 691 ifr = (struct ifreq *)data; 692 if (ifr == 0) { 693 error = EAFNOSUPPORT; /* XXX */ 694 break; 695 } 696 switch (ifr->ifr_addr.sa_family) { 697 698 #ifdef INET 699 case AF_INET: 700 break; 701 #endif 702 703 default: 704 error = EAFNOSUPPORT; 705 break; 706 } 707 break; 708 #endif 709 710 default: 711 error = EINVAL; 712 } 713 splx(s); 714 return (error); 715 } 716 #endif 717