1 /* 2 * ng_tty.c 3 */ 4 5 /*- 6 * Copyright (c) 1996-1999 Whistle Communications, Inc. 7 * All rights reserved. 8 * 9 * Subject to the following obligations and disclaimer of warranty, use and 10 * redistribution of this software, in source or object code forms, with or 11 * without modifications are expressly permitted by Whistle Communications; 12 * provided, however, that: 13 * 1. Any and all reproductions of the source or object code must include the 14 * copyright notice above and the following disclaimer of warranties; and 15 * 2. No rights are granted, in any manner or form, to use Whistle 16 * Communications, Inc. trademarks, including the mark "WHISTLE 17 * COMMUNICATIONS" on advertising, endorsements, or otherwise except as 18 * such appears in the above copyright notice or in the software. 19 * 20 * THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND 21 * TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO 22 * REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE, 23 * INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF 24 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT. 25 * WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANTEE, OR MAKE ANY 26 * REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS 27 * SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE. 28 * IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES 29 * RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING 30 * WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, 31 * PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR 32 * SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY 33 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 34 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 35 * THIS SOFTWARE, EVEN IF WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY 36 * OF SUCH DAMAGE. 37 * 38 * Author: Archie Cobbs <archie@freebsd.org> 39 * 40 * $FreeBSD$ 41 * $Whistle: ng_tty.c,v 1.21 1999/11/01 09:24:52 julian Exp $ 42 */ 43 44 /* 45 * This file implements a terminal line discipline that is also a 46 * netgraph node. Installing this line discipline on a terminal device 47 * instantiates a new netgraph node of this type, which allows access 48 * to the device via the "hook" hook of the node. 49 * 50 * Once the line discipline is installed, you can find out the name 51 * of the corresponding netgraph node via a NGIOCGINFO ioctl(). 52 * 53 * Incoming characters are delievered to the hook one at a time, each 54 * in its own mbuf. You may optionally define a ``hotchar,'' which causes 55 * incoming characters to be buffered up until either the hotchar is 56 * seen or the mbuf is full (MHLEN bytes). Then all buffered characters 57 * are immediately delivered. 58 */ 59 60 #include <sys/param.h> 61 #include <sys/systm.h> 62 #include <sys/conf.h> 63 #include <sys/errno.h> 64 #include <sys/fcntl.h> 65 #include <sys/ioccom.h> 66 #include <sys/kernel.h> 67 #include <sys/malloc.h> 68 #include <sys/mbuf.h> 69 #include <sys/priv.h> 70 #include <sys/socket.h> 71 #include <sys/syslog.h> 72 #include <sys/tty.h> 73 #include <sys/ttycom.h> 74 75 #include <net/if.h> 76 #include <net/if_var.h> 77 78 #include <netgraph/ng_message.h> 79 #include <netgraph/netgraph.h> 80 #include <netgraph/ng_tty.h> 81 82 /* Misc defs */ 83 #define MAX_MBUFQ 3 /* Max number of queued mbufs */ 84 #define NGT_HIWATER 400 /* High water mark on output */ 85 86 /* Per-node private info */ 87 struct ngt_sc { 88 struct tty *tp; /* Terminal device */ 89 node_p node; /* Netgraph node */ 90 hook_p hook; /* Netgraph hook */ 91 struct ifqueue outq; /* Queue of outgoing data */ 92 struct mbuf *m; /* Incoming data buffer */ 93 short hotchar; /* Hotchar, or -1 if none */ 94 u_int flags; /* Flags */ 95 struct callout chand; /* See man timeout(9) */ 96 }; 97 typedef struct ngt_sc *sc_p; 98 99 /* Flags */ 100 #define FLG_DEBUG 0x0002 101 #define FLG_DIE 0x0004 102 103 /* Line discipline methods */ 104 static int ngt_open(struct cdev *dev, struct tty *tp); 105 static int ngt_close(struct tty *tp, int flag); 106 static int ngt_read(struct tty *tp, struct uio *uio, int flag); 107 static int ngt_write(struct tty *tp, struct uio *uio, int flag); 108 static int ngt_tioctl(struct tty *tp, 109 u_long cmd, caddr_t data, int flag, struct thread *); 110 static int ngt_input(int c, struct tty *tp); 111 static int ngt_start(struct tty *tp); 112 113 /* Netgraph methods */ 114 static ng_constructor_t ngt_constructor; 115 static ng_rcvmsg_t ngt_rcvmsg; 116 static ng_shutdown_t ngt_shutdown; 117 static ng_newhook_t ngt_newhook; 118 static ng_connect_t ngt_connect; 119 static ng_rcvdata_t ngt_rcvdata; 120 static ng_disconnect_t ngt_disconnect; 121 static int ngt_mod_event(module_t mod, int event, void *data); 122 123 /* Other stuff */ 124 static void ngt_timeout(node_p node, hook_p hook, void *arg1, int arg2); 125 126 #define ERROUT(x) do { error = (x); goto done; } while (0) 127 128 /* Line discipline descriptor */ 129 static struct linesw ngt_disc = { 130 .l_open = ngt_open, 131 .l_close = ngt_close, 132 .l_read = ngt_read, 133 .l_write = ngt_write, 134 .l_ioctl = ngt_tioctl, 135 .l_rint = ngt_input, 136 .l_start = ngt_start, 137 .l_modem = ttymodem, 138 }; 139 140 /* Netgraph node type descriptor */ 141 static struct ng_type typestruct = { 142 .version = NG_ABI_VERSION, 143 .name = NG_TTY_NODE_TYPE, 144 .mod_event = ngt_mod_event, 145 .constructor = ngt_constructor, 146 .rcvmsg = ngt_rcvmsg, 147 .shutdown = ngt_shutdown, 148 .newhook = ngt_newhook, 149 .connect = ngt_connect, 150 .rcvdata = ngt_rcvdata, 151 .disconnect = ngt_disconnect, 152 }; 153 NETGRAPH_INIT(tty, &typestruct); 154 155 /* 156 * Locking: 157 * 158 * - node private data and tp->t_lsc is protected by mutex in struct 159 * ifqueue, locking is done using IF_XXX() macros. 160 * - in all tty methods we should acquire node ifqueue mutex, when accessing 161 * private data. 162 * - in _rcvdata() we should use locked versions of IF_{EN,DE}QUEUE() since 163 * we may have multiple _rcvdata() threads. 164 * - when calling any of tty methods from netgraph methods, we should 165 * acquire tty locking (now Giant). 166 * 167 * - ngt_unit is incremented atomically. 168 */ 169 170 #define NGTLOCK(sc) IF_LOCK(&sc->outq) 171 #define NGTUNLOCK(sc) IF_UNLOCK(&sc->outq) 172 173 static int ngt_unit; 174 static int ngt_ldisc; 175 176 /****************************************************************** 177 LINE DISCIPLINE METHODS 178 ******************************************************************/ 179 180 /* 181 * Set our line discipline on the tty. 182 * Called from device open routine or ttioctl() 183 */ 184 static int 185 ngt_open(struct cdev *dev, struct tty *tp) 186 { 187 struct thread *const td = curthread; /* XXX */ 188 char name[sizeof(NG_TTY_NODE_TYPE) + 8]; 189 sc_p sc; 190 int error; 191 192 /* Super-user only */ 193 error = priv_check(td, PRIV_NETGRAPH_TTY); 194 if (error) 195 return (error); 196 197 /* Initialize private struct */ 198 MALLOC(sc, sc_p, sizeof(*sc), M_NETGRAPH, M_WAITOK | M_ZERO); 199 if (sc == NULL) 200 return (ENOMEM); 201 202 sc->tp = tp; 203 sc->hotchar = tp->t_hotchar = NG_TTY_DFL_HOTCHAR; 204 mtx_init(&sc->outq.ifq_mtx, "ng_tty node+queue", NULL, MTX_DEF); 205 IFQ_SET_MAXLEN(&sc->outq, MAX_MBUFQ); 206 207 NGTLOCK(sc); 208 209 /* Setup netgraph node */ 210 error = ng_make_node_common(&typestruct, &sc->node); 211 if (error) { 212 NGTUNLOCK(sc); 213 FREE(sc, M_NETGRAPH); 214 return (error); 215 } 216 217 atomic_add_int(&ngt_unit, 1); 218 snprintf(name, sizeof(name), "%s%d", typestruct.name, ngt_unit); 219 220 /* Assign node its name */ 221 if ((error = ng_name_node(sc->node, name))) { 222 sc->flags |= FLG_DIE; 223 NGTUNLOCK(sc); 224 NG_NODE_UNREF(sc->node); 225 log(LOG_ERR, "%s: node name exists?\n", name); 226 return (error); 227 } 228 229 /* Set back pointers */ 230 NG_NODE_SET_PRIVATE(sc->node, sc); 231 tp->t_lsc = sc; 232 233 ng_callout_init(&sc->chand); 234 235 /* 236 * Pre-allocate cblocks to the an appropriate amount. 237 * I'm not sure what is appropriate. 238 */ 239 ttyflush(tp, FREAD | FWRITE); 240 clist_alloc_cblocks(&tp->t_canq, 0, 0); 241 clist_alloc_cblocks(&tp->t_rawq, 0, 0); 242 clist_alloc_cblocks(&tp->t_outq, 243 MLEN + NGT_HIWATER, MLEN + NGT_HIWATER); 244 245 NGTUNLOCK(sc); 246 247 return (0); 248 } 249 250 /* 251 * Line specific close routine, called from device close routine 252 * and from ttioctl. This causes the node to be destroyed as well. 253 */ 254 static int 255 ngt_close(struct tty *tp, int flag) 256 { 257 const sc_p sc = (sc_p) tp->t_lsc; 258 259 ttyflush(tp, FREAD | FWRITE); 260 clist_free_cblocks(&tp->t_outq); 261 if (sc != NULL) { 262 NGTLOCK(sc); 263 if (callout_pending(&sc->chand)) 264 ng_uncallout(&sc->chand, sc->node); 265 tp->t_lsc = NULL; 266 sc->flags |= FLG_DIE; 267 NGTUNLOCK(sc); 268 ng_rmnode_self(sc->node); 269 } 270 return (0); 271 } 272 273 /* 274 * Once the device has been turned into a node, we don't allow reading. 275 */ 276 static int 277 ngt_read(struct tty *tp, struct uio *uio, int flag) 278 { 279 return (EIO); 280 } 281 282 /* 283 * Once the device has been turned into a node, we don't allow writing. 284 */ 285 static int 286 ngt_write(struct tty *tp, struct uio *uio, int flag) 287 { 288 return (EIO); 289 } 290 291 /* 292 * We implement the NGIOCGINFO ioctl() defined in ng_message.h. 293 */ 294 static int 295 ngt_tioctl(struct tty *tp, u_long cmd, caddr_t data, int flag, struct thread *td) 296 { 297 const sc_p sc = (sc_p) tp->t_lsc; 298 299 if (sc == NULL) 300 /* No node attached */ 301 return (0); 302 303 switch (cmd) { 304 case NGIOCGINFO: 305 { 306 struct nodeinfo *const ni = (struct nodeinfo *) data; 307 const node_p node = sc->node; 308 309 bzero(ni, sizeof(*ni)); 310 NGTLOCK(sc); 311 if (NG_NODE_HAS_NAME(node)) 312 strncpy(ni->name, NG_NODE_NAME(node), sizeof(ni->name) - 1); 313 strncpy(ni->type, node->nd_type->name, sizeof(ni->type) - 1); 314 ni->id = (u_int32_t) ng_node2ID(node); 315 ni->hooks = NG_NODE_NUMHOOKS(node); 316 NGTUNLOCK(sc); 317 break; 318 } 319 default: 320 return (ENOIOCTL); 321 } 322 323 return (0); 324 } 325 326 /* 327 * Receive data coming from the device. We get one character at 328 * a time, which is kindof silly. 329 * 330 * Full locking of softc is not required, since we are the only 331 * user of sc->m. 332 */ 333 static int 334 ngt_input(int c, struct tty *tp) 335 { 336 sc_p sc; 337 node_p node; 338 struct mbuf *m; 339 int error = 0; 340 341 sc = (sc_p) tp->t_lsc; 342 if (sc == NULL) 343 /* No node attached */ 344 return (0); 345 346 node = sc->node; 347 348 if (tp != sc->tp) 349 panic("ngt_input"); 350 351 /* Check for error conditions */ 352 if ((tp->t_state & TS_CONNECTED) == 0) { 353 if (sc->flags & FLG_DEBUG) 354 log(LOG_DEBUG, "%s: no carrier\n", NG_NODE_NAME(node)); 355 return (0); 356 } 357 if (c & TTY_ERRORMASK) { 358 /* framing error or overrun on this char */ 359 if (sc->flags & FLG_DEBUG) 360 log(LOG_DEBUG, "%s: line error %x\n", 361 NG_NODE_NAME(node), c & TTY_ERRORMASK); 362 return (0); 363 } 364 c &= TTY_CHARMASK; 365 366 /* Get a new header mbuf if we need one */ 367 if (!(m = sc->m)) { 368 MGETHDR(m, M_DONTWAIT, MT_DATA); 369 if (!m) { 370 if (sc->flags & FLG_DEBUG) 371 log(LOG_ERR, 372 "%s: can't get mbuf\n", NG_NODE_NAME(node)); 373 return (ENOBUFS); 374 } 375 m->m_len = m->m_pkthdr.len = 0; 376 m->m_pkthdr.rcvif = NULL; 377 sc->m = m; 378 } 379 380 /* Add char to mbuf */ 381 *mtod(m, u_char *) = c; 382 m->m_data++; 383 m->m_len++; 384 m->m_pkthdr.len++; 385 386 /* Ship off mbuf if it's time */ 387 if (sc->hotchar == -1 || c == sc->hotchar || m->m_len >= MHLEN) { 388 m->m_data = m->m_pktdat; 389 sc->m = NULL; 390 391 /* 392 * We have built our mbuf without checking that we actually 393 * have a hook to send it. This was done to avoid 394 * acquiring mutex on each character. Check now. 395 * 396 */ 397 398 NGTLOCK(sc); 399 if (sc->hook == NULL) { 400 NGTUNLOCK(sc); 401 m_freem(m); 402 return (0); /* XXX: original behavior */ 403 } 404 NG_SEND_DATA_ONLY(error, sc->hook, m); /* Will queue */ 405 NGTUNLOCK(sc); 406 } 407 408 return (error); 409 } 410 411 /* 412 * This is called when the device driver is ready for more output. 413 * Also called from ngt_rcv_data() when a new mbuf is available for output. 414 */ 415 static int 416 ngt_start(struct tty *tp) 417 { 418 const sc_p sc = (sc_p) tp->t_lsc; 419 420 while (tp->t_outq.c_cc < NGT_HIWATER) { /* XXX 2.2 specific ? */ 421 struct mbuf *m; 422 423 /* Remove first mbuf from queue */ 424 IF_DEQUEUE(&sc->outq, m); 425 if (m == NULL) 426 break; 427 428 /* Send as much of it as possible */ 429 while (m != NULL) { 430 int sent; 431 432 sent = m->m_len 433 - b_to_q(mtod(m, u_char *), m->m_len, &tp->t_outq); 434 m->m_data += sent; 435 m->m_len -= sent; 436 if (m->m_len > 0) 437 break; /* device can't take no more */ 438 m = m_free(m); 439 } 440 441 /* Put remainder of mbuf chain (if any) back on queue */ 442 if (m != NULL) { 443 IF_PREPEND(&sc->outq, m); 444 break; 445 } 446 } 447 448 /* Call output process whether or not there is any output. We are 449 * being called in lieu of ttstart and must do what it would. */ 450 tt_oproc(tp); 451 452 /* This timeout is needed for operation on a pseudo-tty, because the 453 * pty code doesn't call pppstart after it has drained the t_outq. */ 454 /* XXX: outq not locked */ 455 if (!IFQ_IS_EMPTY(&sc->outq) && !callout_pending(&sc->chand)) 456 ng_callout(&sc->chand, sc->node, NULL, 1, ngt_timeout, NULL, 0); 457 458 return (0); 459 } 460 461 /* 462 * We still have data to output to the device, so try sending more. 463 */ 464 static void 465 ngt_timeout(node_p node, hook_p hook, void *arg1, int arg2) 466 { 467 const sc_p sc = NG_NODE_PRIVATE(node); 468 469 mtx_lock(&Giant); 470 ngt_start(sc->tp); 471 mtx_unlock(&Giant); 472 } 473 474 /****************************************************************** 475 NETGRAPH NODE METHODS 476 ******************************************************************/ 477 478 /* 479 * Initialize a new node of this type. 480 * 481 * We only allow nodes to be created as a result of setting 482 * the line discipline on a tty, so always return an error if not. 483 */ 484 static int 485 ngt_constructor(node_p node) 486 { 487 return (EOPNOTSUPP); 488 } 489 490 /* 491 * Add a new hook. There can only be one. 492 */ 493 static int 494 ngt_newhook(node_p node, hook_p hook, const char *name) 495 { 496 const sc_p sc = NG_NODE_PRIVATE(node); 497 498 if (strcmp(name, NG_TTY_HOOK)) 499 return (EINVAL); 500 501 if (sc->hook) 502 return (EISCONN); 503 504 NGTLOCK(sc); 505 sc->hook = hook; 506 NGTUNLOCK(sc); 507 508 return (0); 509 } 510 511 /* 512 * Set the hook into queueing mode (for outgoing packets), 513 * so that we wont deliver mbuf thru the whole graph holding 514 * tty locks. 515 */ 516 static int 517 ngt_connect(hook_p hook) 518 { 519 NG_HOOK_FORCE_QUEUE(NG_HOOK_PEER(hook)); 520 /* 521 * XXX: While ngt_start() is Giant-locked, queue incoming 522 * packets, too. Otherwise we acquire Giant holding some 523 * IP stack locks, e.g. divinp, and this makes WITNESS scream. 524 */ 525 NG_HOOK_FORCE_QUEUE(hook); 526 return (0); 527 } 528 529 /* 530 * Disconnect the hook 531 */ 532 static int 533 ngt_disconnect(hook_p hook) 534 { 535 const sc_p sc = NG_NODE_PRIVATE(NG_HOOK_NODE(hook)); 536 537 if (hook != sc->hook) 538 panic(__func__); 539 540 NGTLOCK(sc); 541 sc->hook = NULL; 542 NGTUNLOCK(sc); 543 544 return (0); 545 } 546 547 /* 548 * Remove this node. The does the netgraph portion of the shutdown. 549 * This should only be called indirectly from ngt_close(). 550 * 551 * tp->t_lsc is already NULL, so we should be protected from 552 * tty calls now. 553 */ 554 static int 555 ngt_shutdown(node_p node) 556 { 557 const sc_p sc = NG_NODE_PRIVATE(node); 558 559 NGTLOCK(sc); 560 if (!(sc->flags & FLG_DIE)) { 561 NGTUNLOCK(sc); 562 return (EOPNOTSUPP); 563 } 564 NGTUNLOCK(sc); 565 566 /* Free resources */ 567 _IF_DRAIN(&sc->outq); 568 mtx_destroy(&(sc)->outq.ifq_mtx); 569 m_freem(sc->m); 570 NG_NODE_UNREF(sc->node); 571 FREE(sc, M_NETGRAPH); 572 573 return (0); 574 } 575 576 /* 577 * Receive incoming data from netgraph system. Put it on our 578 * output queue and start output if necessary. 579 */ 580 static int 581 ngt_rcvdata(hook_p hook, item_p item) 582 { 583 const sc_p sc = NG_NODE_PRIVATE(NG_HOOK_NODE(hook)); 584 struct mbuf *m; 585 int qlen; 586 587 if (hook != sc->hook) 588 panic(__func__); 589 590 NGI_GET_M(item, m); 591 NG_FREE_ITEM(item); 592 593 IF_LOCK(&sc->outq); 594 if (_IF_QFULL(&sc->outq)) { 595 _IF_DROP(&sc->outq); 596 IF_UNLOCK(&sc->outq); 597 NG_FREE_M(m); 598 return (ENOBUFS); 599 } 600 601 _IF_ENQUEUE(&sc->outq, m); 602 qlen = sc->outq.ifq_len; 603 IF_UNLOCK(&sc->outq); 604 605 /* 606 * If qlen > 1, then we should already have a scheduled callout. 607 */ 608 if (qlen == 1) { 609 mtx_lock(&Giant); 610 ngt_start(sc->tp); 611 mtx_unlock(&Giant); 612 } 613 614 return (0); 615 } 616 617 /* 618 * Receive control message 619 */ 620 static int 621 ngt_rcvmsg(node_p node, item_p item, hook_p lasthook) 622 { 623 const sc_p sc = NG_NODE_PRIVATE(node); 624 struct ng_mesg *msg, *resp = NULL; 625 int error = 0; 626 627 NGI_GET_MSG(item, msg); 628 switch (msg->header.typecookie) { 629 case NGM_TTY_COOKIE: 630 switch (msg->header.cmd) { 631 case NGM_TTY_SET_HOTCHAR: 632 { 633 int hotchar; 634 635 if (msg->header.arglen != sizeof(int)) 636 ERROUT(EINVAL); 637 hotchar = *((int *) msg->data); 638 if (hotchar != (u_char) hotchar && hotchar != -1) 639 ERROUT(EINVAL); 640 sc->hotchar = hotchar; /* race condition is OK */ 641 break; 642 } 643 case NGM_TTY_GET_HOTCHAR: 644 NG_MKRESPONSE(resp, msg, sizeof(int), M_NOWAIT); 645 if (!resp) 646 ERROUT(ENOMEM); 647 /* Race condition here is OK */ 648 *((int *) resp->data) = sc->hotchar; 649 break; 650 default: 651 ERROUT(EINVAL); 652 } 653 break; 654 default: 655 ERROUT(EINVAL); 656 } 657 done: 658 NG_RESPOND_MSG(error, node, item, resp); 659 NG_FREE_MSG(msg); 660 return (error); 661 } 662 663 /****************************************************************** 664 INITIALIZATION 665 ******************************************************************/ 666 667 /* 668 * Handle loading and unloading for this node type 669 */ 670 static int 671 ngt_mod_event(module_t mod, int event, void *data) 672 { 673 int error = 0; 674 675 switch (event) { 676 case MOD_LOAD: 677 678 /* Register line discipline */ 679 mtx_lock(&Giant); 680 if ((ngt_ldisc = ldisc_register(NETGRAPHDISC, &ngt_disc)) < 0) { 681 mtx_unlock(&Giant); 682 log(LOG_ERR, "%s: can't register line discipline", 683 __func__); 684 return (EIO); 685 } 686 mtx_unlock(&Giant); 687 break; 688 689 case MOD_UNLOAD: 690 691 /* Unregister line discipline */ 692 mtx_lock(&Giant); 693 ldisc_deregister(ngt_ldisc); 694 mtx_unlock(&Giant); 695 break; 696 697 default: 698 error = EOPNOTSUPP; 699 break; 700 } 701 return (error); 702 } 703