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 7.27 (Berkeley) 03/15/92 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_unit = i++; 156 sc->sc_if.if_mtu = SLMTU; 157 sc->sc_if.if_flags = IFF_POINTOPOINT | SC_AUTOCOMP; 158 sc->sc_if.if_type = IFT_SLIP; 159 sc->sc_if.if_ioctl = slioctl; 160 sc->sc_if.if_output = sloutput; 161 sc->sc_if.if_snd.ifq_maxlen = 50; 162 sc->sc_fastq.ifq_maxlen = 32; 163 if_attach(&sc->sc_if); 164 } 165 } 166 167 static int 168 slinit(sc) 169 register struct sl_softc *sc; 170 { 171 register caddr_t p; 172 173 if (sc->sc_ep == (u_char *) 0) { 174 MCLALLOC(p, M_WAIT); 175 if (p) 176 sc->sc_ep = (u_char *)p + SLBUFSIZE; 177 else { 178 printf("sl%d: can't allocate buffer\n", sc - sl_softc); 179 sc->sc_if.if_flags &= ~IFF_UP; 180 return (0); 181 } 182 } 183 sc->sc_buf = sc->sc_ep - SLMAX; 184 sc->sc_mp = sc->sc_buf; 185 sl_compress_init(&sc->sc_comp); 186 return (1); 187 } 188 189 /* 190 * Line specific open routine. 191 * Attach the given tty to the first available sl unit. 192 */ 193 /* ARGSUSED */ 194 slopen(dev, tp) 195 dev_t dev; 196 register struct tty *tp; 197 { 198 struct proc *p = curproc; /* XXX */ 199 register struct sl_softc *sc; 200 register int nsl; 201 int error; 202 203 if (error = suser(p->p_ucred, &p->p_acflag)) 204 return (error); 205 206 if (tp->t_line == SLIPDISC) 207 return (0); 208 209 for (nsl = NSL, sc = sl_softc; --nsl >= 0; sc++) 210 if (sc->sc_ttyp == NULL) { 211 if (slinit(sc) == 0) 212 return (ENOBUFS); 213 tp->t_sc = (caddr_t)sc; 214 sc->sc_ttyp = tp; 215 sc->sc_if.if_baudrate = tp->t_ospeed; 216 ttyflush(tp, FREAD | FWRITE); 217 return (0); 218 } 219 return (ENXIO); 220 } 221 222 /* 223 * Line specific close routine. 224 * Detach the tty from the sl unit. 225 * Mimics part of ttyclose(). 226 */ 227 slclose(tp) 228 struct tty *tp; 229 { 230 register struct sl_softc *sc; 231 int s; 232 233 ttywflush(tp); 234 s = splimp(); /* actually, max(spltty, splnet) */ 235 tp->t_line = 0; 236 sc = (struct sl_softc *)tp->t_sc; 237 if (sc != NULL) { 238 if_down(&sc->sc_if); 239 sc->sc_ttyp = NULL; 240 tp->t_sc = NULL; 241 MCLFREE((caddr_t)(sc->sc_ep - SLBUFSIZE)); 242 sc->sc_ep = 0; 243 sc->sc_mp = 0; 244 sc->sc_buf = 0; 245 } 246 splx(s); 247 } 248 249 /* 250 * Line specific (tty) ioctl routine. 251 * Provide a way to get the sl unit number. 252 */ 253 /* ARGSUSED */ 254 sltioctl(tp, cmd, data, flag) 255 struct tty *tp; 256 int cmd; 257 caddr_t data; 258 int flag; 259 { 260 struct sl_softc *sc = (struct sl_softc *)tp->t_sc; 261 int s; 262 263 switch (cmd) { 264 case SLIOCGUNIT: 265 *(int *)data = sc->sc_if.if_unit; 266 break; 267 268 default: 269 return (-1); 270 } 271 return (0); 272 } 273 274 /* 275 * Queue a packet. Start transmission if not active. 276 */ 277 sloutput(ifp, m, dst) 278 struct ifnet *ifp; 279 register struct mbuf *m; 280 struct sockaddr *dst; 281 { 282 register struct sl_softc *sc = &sl_softc[ifp->if_unit]; 283 register struct ip *ip; 284 register struct ifqueue *ifq; 285 register int p; 286 int s; 287 288 /* 289 * `Cannot happen' (see slioctl). Someday we will extend 290 * the line protocol to support other address families. 291 */ 292 if (dst->sa_family != AF_INET) { 293 printf("sl%d: af%d not supported\n", sc->sc_if.if_unit, 294 dst->sa_family); 295 m_freem(m); 296 sc->sc_if.if_noproto++; 297 return (EAFNOSUPPORT); 298 } 299 300 if (sc->sc_ttyp == NULL) { 301 m_freem(m); 302 return (ENETDOWN); /* sort of */ 303 } 304 if ((sc->sc_ttyp->t_state & TS_CARR_ON) == 0) { 305 m_freem(m); 306 return (EHOSTUNREACH); 307 } 308 ifq = &sc->sc_if.if_snd; 309 ip = mtod(m, struct ip *); 310 if (ip->ip_tos & IPTOS_LOWDELAY) { 311 ifq = &sc->sc_fastq; 312 p = 1; 313 } else 314 p = 0; 315 if (ip->ip_p == IPPROTO_TCP) { 316 if (sc->sc_if.if_flags & SC_COMPRESS) { 317 /* 318 * The last parameter turns off connection id 319 * compression for background traffic: Since 320 * fastq traffic can jump ahead of the background 321 * traffic, we don't know what order packets will 322 * go on the line. 323 */ 324 p = sl_compress_tcp(m, ip, &sc->sc_comp, p); 325 *mtod(m, u_char *) |= p; 326 } 327 } else if (sc->sc_if.if_flags & SC_NOICMP && ip->ip_p == IPPROTO_ICMP) { 328 m_freem(m); 329 return (ENETRESET); /* XXX ? */ 330 } 331 s = splimp(); 332 if (IF_QFULL(ifq)) { 333 IF_DROP(ifq); 334 m_freem(m); 335 splx(s); 336 sc->sc_if.if_oerrors++; 337 return (ENOBUFS); 338 } 339 IF_ENQUEUE(ifq, m); 340 sc->sc_if.if_lastchange = time; 341 if (sc->sc_ttyp->t_outq.c_cc == 0) 342 slstart(sc->sc_ttyp); 343 splx(s); 344 return (0); 345 } 346 347 /* 348 * Start output on interface. Get another datagram 349 * to send from the interface queue and map it to 350 * the interface before starting output. 351 */ 352 slstart(tp) 353 register struct tty *tp; 354 { 355 register struct sl_softc *sc = (struct sl_softc *)tp->t_sc; 356 register struct mbuf *m; 357 register u_char *cp; 358 int s; 359 struct mbuf *m2; 360 extern int cfreecount; 361 362 for (;;) { 363 /* 364 * If there is more in the output queue, just send it now. 365 * We are being called in lieu of ttstart and must do what 366 * it would. 367 */ 368 if (tp->t_outq.c_cc != 0) { 369 (*tp->t_oproc)(tp); 370 if (tp->t_outq.c_cc > SLIP_HIWAT) 371 return; 372 } 373 /* 374 * This happens briefly when the line shuts down. 375 */ 376 if (sc == NULL) 377 return; 378 379 /* 380 * Get a packet and send it to the interface. 381 */ 382 s = splimp(); 383 IF_DEQUEUE(&sc->sc_fastq, m); 384 if (m) 385 sc->sc_if.if_omcasts++; /* XXX */ 386 else 387 IF_DEQUEUE(&sc->sc_if.if_snd, m); 388 splx(s); 389 if (m == NULL) 390 return; 391 sc->sc_if.if_lastchange = time; 392 393 /* 394 * If system is getting low on clists, just flush our 395 * output queue (if the stuff was important, it'll get 396 * retransmitted). 397 */ 398 if (cfreecount < CLISTRESERVE + SLMTU) { 399 m_freem(m); 400 sc->sc_if.if_collisions++; 401 continue; 402 } 403 /* 404 * The extra FRAME_END will start up a new packet, and thus 405 * will flush any accumulated garbage. We do this whenever 406 * the line may have been idle for some time. 407 */ 408 if (tp->t_outq.c_cc == 0) { 409 ++sc->sc_if.if_obytes; 410 (void) putc(FRAME_END, &tp->t_outq); 411 } 412 413 while (m) { 414 register u_char *ep; 415 416 cp = mtod(m, u_char *); ep = cp + m->m_len; 417 while (cp < ep) { 418 /* 419 * Find out how many bytes in the string we can 420 * handle without doing something special. 421 */ 422 register u_char *bp = cp; 423 424 while (cp < ep) { 425 switch (*cp++) { 426 case FRAME_ESCAPE: 427 case FRAME_END: 428 --cp; 429 goto out; 430 } 431 } 432 out: 433 if (cp > bp) { 434 /* 435 * Put n characters at once 436 * into the tty output queue. 437 */ 438 if (b_to_q((char *)bp, cp - bp, &tp->t_outq)) 439 break; 440 sc->sc_if.if_obytes += cp - bp; 441 } 442 /* 443 * If there are characters left in the mbuf, 444 * the first one must be special.. 445 * Put it out in a different form. 446 */ 447 if (cp < ep) { 448 if (putc(FRAME_ESCAPE, &tp->t_outq)) 449 break; 450 if (putc(*cp++ == FRAME_ESCAPE ? 451 TRANS_FRAME_ESCAPE : TRANS_FRAME_END, 452 &tp->t_outq)) { 453 (void) unputc(&tp->t_outq); 454 break; 455 } 456 sc->sc_if.if_obytes += 2; 457 } 458 } 459 MFREE(m, m2); 460 m = m2; 461 } 462 463 if (putc(FRAME_END, &tp->t_outq)) { 464 /* 465 * Not enough room. Remove a char to make room 466 * and end the packet normally. 467 * If you get many collisions (more than one or two 468 * a day) you probably do not have enough clists 469 * and you should increase "nclist" in param.c. 470 */ 471 (void) unputc(&tp->t_outq); 472 (void) putc(FRAME_END, &tp->t_outq); 473 sc->sc_if.if_collisions++; 474 } else { 475 ++sc->sc_if.if_obytes; 476 sc->sc_if.if_opackets++; 477 } 478 } 479 } 480 481 /* 482 * Copy data buffer to mbuf chain; add ifnet pointer. 483 */ 484 static struct mbuf * 485 sl_btom(sc, len) 486 register struct sl_softc *sc; 487 register int len; 488 { 489 register struct mbuf *m; 490 491 MGETHDR(m, M_DONTWAIT, MT_DATA); 492 if (m == NULL) 493 return (NULL); 494 495 /* 496 * If we have more than MHLEN bytes, it's cheaper to 497 * queue the cluster we just filled & allocate a new one 498 * for the input buffer. Otherwise, fill the mbuf we 499 * allocated above. Note that code in the input routine 500 * guarantees that packet will fit in a cluster. 501 */ 502 if (len >= MHLEN) { 503 MCLGET(m, M_DONTWAIT); 504 if ((m->m_flags & M_EXT) == 0) { 505 /* 506 * we couldn't get a cluster - if memory's this 507 * low, it's time to start dropping packets. 508 */ 509 (void) m_free(m); 510 return (NULL); 511 } 512 sc->sc_ep = mtod(m, u_char *) + SLBUFSIZE; 513 m->m_data = (caddr_t)sc->sc_buf; 514 m->m_ext.ext_buf = (caddr_t)((int)sc->sc_buf &~ MCLOFSET); 515 } else 516 bcopy((caddr_t)sc->sc_buf, mtod(m, caddr_t), len); 517 518 m->m_len = len; 519 m->m_pkthdr.len = len; 520 m->m_pkthdr.rcvif = &sc->sc_if; 521 return (m); 522 } 523 524 /* 525 * tty interface receiver interrupt. 526 */ 527 slinput(c, tp) 528 register int c; 529 register struct tty *tp; 530 { 531 register struct sl_softc *sc; 532 register struct mbuf *m; 533 register int len; 534 int s; 535 536 tk_nin++; 537 sc = (struct sl_softc *)tp->t_sc; 538 if (sc == NULL) 539 return; 540 if (!(tp->t_state&TS_CARR_ON)) /* XXX */ 541 return; 542 543 ++sc->sc_if.if_ibytes; 544 c &= 0xff; /* XXX */ 545 546 #ifdef ABT_ESC 547 if (sc->sc_if.if_flags & IFF_DEBUG) { 548 if (c == ABT_ESC) { 549 /* 550 * If we have a previous abort, see whether 551 * this one is within the time limit. 552 */ 553 if (sc->sc_abortcount && 554 time.tv_sec >= sc->sc_starttime + ABT_WINDOW) 555 sc->sc_abortcount = 0; 556 /* 557 * If we see an abort after "idle" time, count it; 558 * record when the first abort escape arrived. 559 */ 560 if (time.tv_sec >= sc->sc_lasttime + ABT_IDLE) { 561 if (++sc->sc_abortcount == 1) 562 sc->sc_starttime = time.tv_sec; 563 if (sc->sc_abortcount >= ABT_COUNT) { 564 slclose(tp); 565 return; 566 } 567 } 568 } else 569 sc->sc_abortcount = 0; 570 sc->sc_lasttime = time.tv_sec; 571 } 572 #endif 573 574 switch (c) { 575 576 case TRANS_FRAME_ESCAPE: 577 if (sc->sc_escape) 578 c = FRAME_ESCAPE; 579 break; 580 581 case TRANS_FRAME_END: 582 if (sc->sc_escape) 583 c = FRAME_END; 584 break; 585 586 case FRAME_ESCAPE: 587 sc->sc_escape = 1; 588 return; 589 590 case FRAME_END: 591 len = sc->sc_mp - sc->sc_buf; 592 if (len < 3) 593 /* less than min length packet - ignore */ 594 goto newpack; 595 596 if ((c = (*sc->sc_buf & 0xf0)) != (IPVERSION << 4)) { 597 if (c & 0x80) 598 c = TYPE_COMPRESSED_TCP; 599 else if (c == TYPE_UNCOMPRESSED_TCP) 600 *sc->sc_buf &= 0x4f; /* XXX */ 601 /* 602 * We've got something that's not an IP packet. 603 * If compression is enabled, try to decompress it. 604 * Otherwise, if `auto-enable' compression is on and 605 * it's a reasonable packet, decompress it and then 606 * enable compression. Otherwise, drop it. 607 */ 608 if (sc->sc_if.if_flags & SC_COMPRESS) { 609 len = sl_uncompress_tcp(&sc->sc_buf, len, 610 (u_int)c, &sc->sc_comp); 611 if (len <= 0) 612 goto error; 613 } else if ((sc->sc_if.if_flags & SC_AUTOCOMP) && 614 c == TYPE_UNCOMPRESSED_TCP && len >= 40) { 615 len = sl_uncompress_tcp(&sc->sc_buf, len, 616 (u_int)c, &sc->sc_comp); 617 if (len <= 0) 618 goto error; 619 sc->sc_if.if_flags |= SC_COMPRESS; 620 } else 621 goto error; 622 } 623 m = sl_btom(sc, len); 624 if (m == NULL) 625 goto error; 626 627 sc->sc_if.if_ipackets++; 628 sc->sc_if.if_lastchange = time; 629 s = splimp(); 630 if (IF_QFULL(&ipintrq)) { 631 IF_DROP(&ipintrq); 632 sc->sc_if.if_ierrors++; 633 sc->sc_if.if_iqdrops++; 634 m_freem(m); 635 } else { 636 IF_ENQUEUE(&ipintrq, m); 637 schednetisr(NETISR_IP); 638 } 639 splx(s); 640 goto newpack; 641 } 642 if (sc->sc_mp < sc->sc_ep) { 643 *sc->sc_mp++ = c; 644 sc->sc_escape = 0; 645 return; 646 } 647 error: 648 sc->sc_if.if_ierrors++; 649 newpack: 650 sc->sc_mp = sc->sc_buf = sc->sc_ep - SLMAX; 651 sc->sc_escape = 0; 652 } 653 654 /* 655 * Process an ioctl request. 656 */ 657 slioctl(ifp, cmd, data) 658 register struct ifnet *ifp; 659 int cmd; 660 caddr_t data; 661 { 662 register struct ifaddr *ifa = (struct ifaddr *)data; 663 int s = splimp(), error = 0; 664 665 switch (cmd) { 666 667 case SIOCSIFADDR: 668 if (ifa->ifa_addr->sa_family == AF_INET) 669 ifp->if_flags |= IFF_UP; 670 else 671 error = EAFNOSUPPORT; 672 break; 673 674 case SIOCSIFDSTADDR: 675 if (ifa->ifa_addr->sa_family != AF_INET) 676 error = EAFNOSUPPORT; 677 break; 678 679 default: 680 error = EINVAL; 681 } 682 splx(s); 683 return (error); 684 } 685 #endif 686