FreeBSD/Linux Kernel Cross Reference
sys/netgraph/ng_tty.c
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: src/sys/netgraph/ng_tty.c,v 1.29.2.3 2005/02/12 09:17:31 glebius Exp $
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/socket.h>
70 #include <sys/syslog.h>
71 #include <sys/tty.h>
72 #include <sys/ttycom.h>
73
74 #include <net/if.h>
75 #include <net/if_var.h>
76
77 #include <netgraph/ng_message.h>
78 #include <netgraph/netgraph.h>
79 #include <netgraph/ng_tty.h>
80
81 /* Misc defs */
82 #define MAX_MBUFQ 3 /* Max number of queued mbufs */
83 #define NGT_HIWATER 400 /* High water mark on output */
84
85 /* Per-node private info */
86 struct ngt_sc {
87 struct tty *tp; /* Terminal device */
88 node_p node; /* Netgraph node */
89 hook_p hook; /* Netgraph hook */
90 struct ifqueue outq; /* Queue of outgoing data */
91 struct mbuf *m; /* Incoming data buffer */
92 short hotchar; /* Hotchar, or -1 if none */
93 u_int flags; /* Flags */
94 struct callout chand; /* See man timeout(9) */
95 };
96 typedef struct ngt_sc *sc_p;
97
98 /* Flags */
99 #define FLG_DEBUG 0x0002
100 #define FLG_DIE 0x0004
101
102 /* Line discipline methods */
103 static int ngt_open(struct cdev *dev, struct tty *tp);
104 static int ngt_close(struct tty *tp, int flag);
105 static int ngt_read(struct tty *tp, struct uio *uio, int flag);
106 static int ngt_write(struct tty *tp, struct uio *uio, int flag);
107 static int ngt_tioctl(struct tty *tp,
108 u_long cmd, caddr_t data, int flag, struct thread *);
109 static int ngt_input(int c, struct tty *tp);
110 static int ngt_start(struct tty *tp);
111
112 /* Netgraph methods */
113 static ng_constructor_t ngt_constructor;
114 static ng_rcvmsg_t ngt_rcvmsg;
115 static ng_shutdown_t ngt_shutdown;
116 static ng_newhook_t ngt_newhook;
117 static ng_connect_t ngt_connect;
118 static ng_rcvdata_t ngt_rcvdata;
119 static ng_disconnect_t ngt_disconnect;
120 static int ngt_mod_event(module_t mod, int event, void *data);
121
122 /* Other stuff */
123 static void ngt_timeout(node_p node, hook_p hook, void *arg1, int arg2);
124
125 #define ERROUT(x) do { error = (x); goto done; } while (0)
126
127 /* Line discipline descriptor */
128 static struct linesw ngt_disc = {
129 .l_open = ngt_open,
130 .l_close = ngt_close,
131 .l_read = ngt_read,
132 .l_write = ngt_write,
133 .l_ioctl = ngt_tioctl,
134 .l_rint = ngt_input,
135 .l_start = ngt_start,
136 .l_modem = ttymodem,
137 };
138
139 /* Netgraph node type descriptor */
140 static struct ng_type typestruct = {
141 .version = NG_ABI_VERSION,
142 .name = NG_TTY_NODE_TYPE,
143 .mod_event = ngt_mod_event,
144 .constructor = ngt_constructor,
145 .rcvmsg = ngt_rcvmsg,
146 .shutdown = ngt_shutdown,
147 .newhook = ngt_newhook,
148 .connect = ngt_connect,
149 .rcvdata = ngt_rcvdata,
150 .disconnect = ngt_disconnect,
151 };
152 NETGRAPH_INIT(tty, &typestruct);
153
154 /*
155 * Locking:
156 *
157 * - node private data and tp->t_sc is protected by mutex in struct
158 * ifqueue, locking is done using IF_XXX() macros.
159 * - in all tty methods we should acquire node ifqueue mutex, when accessing
160 * private data.
161 * - in _rcvdata() we should use locked versions of IF_{EN,DE}QUEUE() since
162 * we may have multiple _rcvdata() threads.
163 * - when calling any of tty methods from netgraph methods, we should
164 * acquire tty locking (now Giant).
165 *
166 * - ngt_unit is incremented atomically.
167 */
168
169 #define NGTLOCK(sc) IF_LOCK(&sc->outq)
170 #define NGTUNLOCK(sc) IF_UNLOCK(&sc->outq)
171
172 static int ngt_unit;
173 static int ngt_ldisc;
174
175 /******************************************************************
176 LINE DISCIPLINE METHODS
177 ******************************************************************/
178
179 /*
180 * Set our line discipline on the tty.
181 * Called from device open routine or ttioctl()
182 */
183 static int
184 ngt_open(struct cdev *dev, struct tty *tp)
185 {
186 struct thread *const td = curthread; /* XXX */
187 char name[sizeof(NG_TTY_NODE_TYPE) + 8];
188 sc_p sc;
189 int error;
190
191 /* Super-user only */
192 if ((error = suser(td)))
193 return (error);
194
195 /* Initialize private struct */
196 MALLOC(sc, sc_p, sizeof(*sc), M_NETGRAPH, M_WAITOK | M_ZERO);
197 if (sc == NULL)
198 return (ENOMEM);
199
200 sc->tp = tp;
201 sc->hotchar = tp->t_hotchar = NG_TTY_DFL_HOTCHAR;
202 mtx_init(&sc->outq.ifq_mtx, "ng_tty node+queue", NULL, MTX_DEF);
203 IFQ_SET_MAXLEN(&sc->outq, MAX_MBUFQ);
204
205 NGTLOCK(sc);
206
207 /* Setup netgraph node */
208 error = ng_make_node_common(&typestruct, &sc->node);
209 if (error) {
210 NGTUNLOCK(sc);
211 FREE(sc, M_NETGRAPH);
212 return (error);
213 }
214
215 atomic_add_int(&ngt_unit, 1);
216 snprintf(name, sizeof(name), "%s%d", typestruct.name, ngt_unit);
217
218 /* Assign node its name */
219 if ((error = ng_name_node(sc->node, name))) {
220 sc->flags |= FLG_DIE;
221 NGTUNLOCK(sc);
222 NG_NODE_UNREF(sc->node);
223 log(LOG_ERR, "%s: node name exists?\n", name);
224 return (error);
225 }
226
227 /* Set back pointers */
228 NG_NODE_SET_PRIVATE(sc->node, sc);
229 tp->t_sc = sc;
230
231 ng_callout_init(&sc->chand);
232
233 /*
234 * Pre-allocate cblocks to the an appropriate amount.
235 * I'm not sure what is appropriate.
236 */
237 ttyflush(tp, FREAD | FWRITE);
238 clist_alloc_cblocks(&tp->t_canq, 0, 0);
239 clist_alloc_cblocks(&tp->t_rawq, 0, 0);
240 clist_alloc_cblocks(&tp->t_outq,
241 MLEN + NGT_HIWATER, MLEN + NGT_HIWATER);
242
243 NGTUNLOCK(sc);
244
245 return (0);
246 }
247
248 /*
249 * Line specific close routine, called from device close routine
250 * and from ttioctl. This causes the node to be destroyed as well.
251 */
252 static int
253 ngt_close(struct tty *tp, int flag)
254 {
255 const sc_p sc = (sc_p) tp->t_sc;
256
257 ttyflush(tp, FREAD | FWRITE);
258 clist_free_cblocks(&tp->t_outq);
259 if (sc != NULL) {
260 NGTLOCK(sc);
261 if (callout_pending(&sc->chand))
262 ng_uncallout(&sc->chand, sc->node);
263 tp->t_sc = NULL;
264 sc->flags |= FLG_DIE;
265 NGTUNLOCK(sc);
266 ng_rmnode_self(sc->node);
267 }
268 return (0);
269 }
270
271 /*
272 * Once the device has been turned into a node, we don't allow reading.
273 */
274 static int
275 ngt_read(struct tty *tp, struct uio *uio, int flag)
276 {
277 return (EIO);
278 }
279
280 /*
281 * Once the device has been turned into a node, we don't allow writing.
282 */
283 static int
284 ngt_write(struct tty *tp, struct uio *uio, int flag)
285 {
286 return (EIO);
287 }
288
289 /*
290 * We implement the NGIOCGINFO ioctl() defined in ng_message.h.
291 */
292 static int
293 ngt_tioctl(struct tty *tp, u_long cmd, caddr_t data, int flag, struct thread *td)
294 {
295 const sc_p sc = (sc_p) tp->t_sc;
296
297 if (sc == NULL)
298 /* No node attached */
299 return (0);
300
301 switch (cmd) {
302 case NGIOCGINFO:
303 {
304 struct nodeinfo *const ni = (struct nodeinfo *) data;
305 const node_p node = sc->node;
306
307 bzero(ni, sizeof(*ni));
308 NGTLOCK(sc);
309 if (NG_NODE_HAS_NAME(node))
310 strncpy(ni->name, NG_NODE_NAME(node), sizeof(ni->name) - 1);
311 strncpy(ni->type, node->nd_type->name, sizeof(ni->type) - 1);
312 ni->id = (u_int32_t) ng_node2ID(node);
313 ni->hooks = NG_NODE_NUMHOOKS(node);
314 NGTUNLOCK(sc);
315 break;
316 }
317 default:
318 return (ENOIOCTL);
319 }
320
321 return (0);
322 }
323
324 /*
325 * Receive data coming from the device. We get one character at
326 * a time, which is kindof silly.
327 *
328 * Full locking of softc is not required, since we are the only
329 * user of sc->m.
330 */
331 static int
332 ngt_input(int c, struct tty *tp)
333 {
334 const sc_p sc = (sc_p) tp->t_sc;
335 const node_p node = sc->node;
336 struct mbuf *m;
337 int error = 0;
338
339 if (sc == NULL)
340 /* No node attached */
341 return (0);
342
343 if (tp != sc->tp)
344 panic("ngt_input");
345
346 /* Check for error conditions */
347 if ((tp->t_state & TS_CONNECTED) == 0) {
348 if (sc->flags & FLG_DEBUG)
349 log(LOG_DEBUG, "%s: no carrier\n", NG_NODE_NAME(node));
350 return (0);
351 }
352 if (c & TTY_ERRORMASK) {
353 /* framing error or overrun on this char */
354 if (sc->flags & FLG_DEBUG)
355 log(LOG_DEBUG, "%s: line error %x\n",
356 NG_NODE_NAME(node), c & TTY_ERRORMASK);
357 return (0);
358 }
359 c &= TTY_CHARMASK;
360
361 /* Get a new header mbuf if we need one */
362 if (!(m = sc->m)) {
363 MGETHDR(m, M_DONTWAIT, MT_DATA);
364 if (!m) {
365 if (sc->flags & FLG_DEBUG)
366 log(LOG_ERR,
367 "%s: can't get mbuf\n", NG_NODE_NAME(node));
368 return (ENOBUFS);
369 }
370 m->m_len = m->m_pkthdr.len = 0;
371 m->m_pkthdr.rcvif = NULL;
372 sc->m = m;
373 }
374
375 /* Add char to mbuf */
376 *mtod(m, u_char *) = c;
377 m->m_data++;
378 m->m_len++;
379 m->m_pkthdr.len++;
380
381 /* Ship off mbuf if it's time */
382 if (sc->hotchar == -1 || c == sc->hotchar || m->m_len >= MHLEN) {
383 m->m_data = m->m_pktdat;
384 sc->m = NULL;
385
386 /*
387 * We have built our mbuf without checking that we actually
388 * have a hook to send it. This was done to avoid
389 * acquiring mutex on each character. Check now.
390 *
391 */
392
393 NGTLOCK(sc);
394 if (sc->hook == NULL) {
395 NGTUNLOCK(sc);
396 m_freem(m);
397 return (0); /* XXX: original behavior */
398 }
399 NG_SEND_DATA_ONLY(error, sc->hook, m); /* Will queue */
400 NGTUNLOCK(sc);
401 }
402
403 return (error);
404 }
405
406 /*
407 * This is called when the device driver is ready for more output.
408 * Also called from ngt_rcv_data() when a new mbuf is available for output.
409 */
410 static int
411 ngt_start(struct tty *tp)
412 {
413 const sc_p sc = (sc_p) tp->t_sc;
414
415 while (tp->t_outq.c_cc < NGT_HIWATER) { /* XXX 2.2 specific ? */
416 struct mbuf *m;
417
418 /* Remove first mbuf from queue */
419 IF_DEQUEUE(&sc->outq, m);
420 if (m == NULL)
421 break;
422
423 /* Send as much of it as possible */
424 while (m != NULL) {
425 int sent;
426
427 sent = m->m_len
428 - b_to_q(mtod(m, u_char *), m->m_len, &tp->t_outq);
429 m->m_data += sent;
430 m->m_len -= sent;
431 if (m->m_len > 0)
432 break; /* device can't take no more */
433 m = m_free(m);
434 }
435
436 /* Put remainder of mbuf chain (if any) back on queue */
437 if (m != NULL) {
438 IF_PREPEND(&sc->outq, m);
439 break;
440 }
441 }
442
443 /* Call output process whether or not there is any output. We are
444 * being called in lieu of ttstart and must do what it would. */
445 if (tp->t_oproc != NULL)
446 (*tp->t_oproc) (tp);
447
448 /* This timeout is needed for operation on a pseudo-tty, because the
449 * pty code doesn't call pppstart after it has drained the t_outq. */
450 /* XXX: outq not locked */
451 if (!IFQ_IS_EMPTY(&sc->outq) && !callout_pending(&sc->chand))
452 ng_callout(&sc->chand, sc->node, NULL, 1, ngt_timeout, NULL, 0);
453
454 return (0);
455 }
456
457 /*
458 * We still have data to output to the device, so try sending more.
459 */
460 static void
461 ngt_timeout(node_p node, hook_p hook, void *arg1, int arg2)
462 {
463 const sc_p sc = NG_NODE_PRIVATE(node);
464
465 mtx_lock(&Giant);
466 ngt_start(sc->tp);
467 mtx_unlock(&Giant);
468 }
469
470 /******************************************************************
471 NETGRAPH NODE METHODS
472 ******************************************************************/
473
474 /*
475 * Initialize a new node of this type.
476 *
477 * We only allow nodes to be created as a result of setting
478 * the line discipline on a tty, so always return an error if not.
479 */
480 static int
481 ngt_constructor(node_p node)
482 {
483 return (EOPNOTSUPP);
484 }
485
486 /*
487 * Add a new hook. There can only be one.
488 */
489 static int
490 ngt_newhook(node_p node, hook_p hook, const char *name)
491 {
492 const sc_p sc = NG_NODE_PRIVATE(node);
493
494 if (strcmp(name, NG_TTY_HOOK))
495 return (EINVAL);
496
497 if (sc->hook)
498 return (EISCONN);
499
500 NGTLOCK(sc);
501 sc->hook = hook;
502 NGTUNLOCK(sc);
503
504 return (0);
505 }
506
507 /*
508 * Set the hook into queueing mode (for outgoing packets),
509 * so that we wont deliver mbuf thru the whole graph holding
510 * tty locks.
511 */
512 static int
513 ngt_connect(hook_p hook)
514 {
515 NG_HOOK_FORCE_QUEUE(NG_HOOK_PEER(hook));
516 /*
517 * XXX: While ngt_start() is Giant-locked, queue incoming
518 * packets, too. Otherwise we acquire Giant holding some
519 * IP stack locks, e.g. divinp, and this makes WITNESS scream.
520 */
521 NG_HOOK_FORCE_QUEUE(hook);
522 return (0);
523 }
524
525 /*
526 * Disconnect the hook
527 */
528 static int
529 ngt_disconnect(hook_p hook)
530 {
531 const sc_p sc = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
532
533 if (hook != sc->hook)
534 panic(__func__);
535
536 NGTLOCK(sc);
537 sc->hook = NULL;
538 NGTUNLOCK(sc);
539
540 return (0);
541 }
542
543 /*
544 * Remove this node. The does the netgraph portion of the shutdown.
545 * This should only be called indirectly from ngt_close().
546 *
547 * tp->t_sc is already NULL, so we should be protected from
548 * tty calls now.
549 */
550 static int
551 ngt_shutdown(node_p node)
552 {
553 const sc_p sc = NG_NODE_PRIVATE(node);
554
555 NGTLOCK(sc);
556 if (!(sc->flags & FLG_DIE)) {
557 NGTUNLOCK(sc);
558 return (EOPNOTSUPP);
559 }
560 NGTUNLOCK(sc);
561
562 /* Free resources */
563 _IF_DRAIN(&sc->outq);
564 mtx_destroy(&(sc)->outq.ifq_mtx);
565 m_freem(sc->m);
566 NG_NODE_UNREF(sc->node);
567 FREE(sc, M_NETGRAPH);
568
569 return (0);
570 }
571
572 /*
573 * Receive incoming data from netgraph system. Put it on our
574 * output queue and start output if necessary.
575 */
576 static int
577 ngt_rcvdata(hook_p hook, item_p item)
578 {
579 const sc_p sc = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
580 struct mbuf *m;
581 int qlen;
582
583 if (hook != sc->hook)
584 panic(__func__);
585
586 NGI_GET_M(item, m);
587 NG_FREE_ITEM(item);
588
589 IF_LOCK(&sc->outq);
590 if (_IF_QFULL(&sc->outq)) {
591 _IF_DROP(&sc->outq);
592 IF_UNLOCK(&sc->outq);
593 NG_FREE_M(m);
594 return (ENOBUFS);
595 }
596
597 _IF_ENQUEUE(&sc->outq, m);
598 qlen = sc->outq.ifq_len;
599 IF_UNLOCK(&sc->outq);
600
601 /*
602 * If qlen > 1, then we should already have a scheduled callout.
603 */
604 if (qlen == 1) {
605 mtx_lock(&Giant);
606 ngt_start(sc->tp);
607 mtx_unlock(&Giant);
608 }
609
610 return (0);
611 }
612
613 /*
614 * Receive control message
615 */
616 static int
617 ngt_rcvmsg(node_p node, item_p item, hook_p lasthook)
618 {
619 const sc_p sc = NG_NODE_PRIVATE(node);
620 struct ng_mesg *msg, *resp = NULL;
621 int error = 0;
622
623 NGI_GET_MSG(item, msg);
624 switch (msg->header.typecookie) {
625 case NGM_TTY_COOKIE:
626 switch (msg->header.cmd) {
627 case NGM_TTY_SET_HOTCHAR:
628 {
629 int hotchar;
630
631 if (msg->header.arglen != sizeof(int))
632 ERROUT(EINVAL);
633 hotchar = *((int *) msg->data);
634 if (hotchar != (u_char) hotchar && hotchar != -1)
635 ERROUT(EINVAL);
636 sc->hotchar = hotchar; /* race condition is OK */
637 break;
638 }
639 case NGM_TTY_GET_HOTCHAR:
640 NG_MKRESPONSE(resp, msg, sizeof(int), M_NOWAIT);
641 if (!resp)
642 ERROUT(ENOMEM);
643 /* Race condition here is OK */
644 *((int *) resp->data) = sc->hotchar;
645 break;
646 default:
647 ERROUT(EINVAL);
648 }
649 break;
650 default:
651 ERROUT(EINVAL);
652 }
653 done:
654 NG_RESPOND_MSG(error, node, item, resp);
655 NG_FREE_MSG(msg);
656 return (error);
657 }
658
659 /******************************************************************
660 INITIALIZATION
661 ******************************************************************/
662
663 /*
664 * Handle loading and unloading for this node type
665 */
666 static int
667 ngt_mod_event(module_t mod, int event, void *data)
668 {
669 int error = 0;
670
671 switch (event) {
672 case MOD_LOAD:
673
674 /* Register line discipline */
675 mtx_lock(&Giant);
676 if ((ngt_ldisc = ldisc_register(NETGRAPHDISC, &ngt_disc)) < 0) {
677 mtx_unlock(&Giant);
678 log(LOG_ERR, "%s: can't register line discipline",
679 __func__);
680 return (EIO);
681 }
682 mtx_unlock(&Giant);
683 break;
684
685 case MOD_UNLOAD:
686
687 /* Unregister line discipline */
688 mtx_lock(&Giant);
689 ldisc_deregister(ngt_ldisc);
690 mtx_unlock(&Giant);
691 break;
692
693 default:
694 error = EOPNOTSUPP;
695 break;
696 }
697 return (error);
698 }
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