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: releng/6.1/sys/netgraph/ng_tty.c 151113 2005-10-09 00:19:28Z tanimura $
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_lsc 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_lsc = 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_lsc;
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_lsc = 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_lsc;
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 sc_p sc;
335 node_p node;
336 struct mbuf *m;
337 int error = 0;
338
339 sc = (sc_p) tp->t_lsc;
340 if (sc == NULL)
341 /* No node attached */
342 return (0);
343
344 node = sc->node;
345
346 if (tp != sc->tp)
347 panic("ngt_input");
348
349 /* Check for error conditions */
350 if ((tp->t_state & TS_CONNECTED) == 0) {
351 if (sc->flags & FLG_DEBUG)
352 log(LOG_DEBUG, "%s: no carrier\n", NG_NODE_NAME(node));
353 return (0);
354 }
355 if (c & TTY_ERRORMASK) {
356 /* framing error or overrun on this char */
357 if (sc->flags & FLG_DEBUG)
358 log(LOG_DEBUG, "%s: line error %x\n",
359 NG_NODE_NAME(node), c & TTY_ERRORMASK);
360 return (0);
361 }
362 c &= TTY_CHARMASK;
363
364 /* Get a new header mbuf if we need one */
365 if (!(m = sc->m)) {
366 MGETHDR(m, M_DONTWAIT, MT_DATA);
367 if (!m) {
368 if (sc->flags & FLG_DEBUG)
369 log(LOG_ERR,
370 "%s: can't get mbuf\n", NG_NODE_NAME(node));
371 return (ENOBUFS);
372 }
373 m->m_len = m->m_pkthdr.len = 0;
374 m->m_pkthdr.rcvif = NULL;
375 sc->m = m;
376 }
377
378 /* Add char to mbuf */
379 *mtod(m, u_char *) = c;
380 m->m_data++;
381 m->m_len++;
382 m->m_pkthdr.len++;
383
384 /* Ship off mbuf if it's time */
385 if (sc->hotchar == -1 || c == sc->hotchar || m->m_len >= MHLEN) {
386 m->m_data = m->m_pktdat;
387 sc->m = NULL;
388
389 /*
390 * We have built our mbuf without checking that we actually
391 * have a hook to send it. This was done to avoid
392 * acquiring mutex on each character. Check now.
393 *
394 */
395
396 NGTLOCK(sc);
397 if (sc->hook == NULL) {
398 NGTUNLOCK(sc);
399 m_freem(m);
400 return (0); /* XXX: original behavior */
401 }
402 NG_SEND_DATA_ONLY(error, sc->hook, m); /* Will queue */
403 NGTUNLOCK(sc);
404 }
405
406 return (error);
407 }
408
409 /*
410 * This is called when the device driver is ready for more output.
411 * Also called from ngt_rcv_data() when a new mbuf is available for output.
412 */
413 static int
414 ngt_start(struct tty *tp)
415 {
416 const sc_p sc = (sc_p) tp->t_lsc;
417
418 while (tp->t_outq.c_cc < NGT_HIWATER) { /* XXX 2.2 specific ? */
419 struct mbuf *m;
420
421 /* Remove first mbuf from queue */
422 IF_DEQUEUE(&sc->outq, m);
423 if (m == NULL)
424 break;
425
426 /* Send as much of it as possible */
427 while (m != NULL) {
428 int sent;
429
430 sent = m->m_len
431 - b_to_q(mtod(m, u_char *), m->m_len, &tp->t_outq);
432 m->m_data += sent;
433 m->m_len -= sent;
434 if (m->m_len > 0)
435 break; /* device can't take no more */
436 m = m_free(m);
437 }
438
439 /* Put remainder of mbuf chain (if any) back on queue */
440 if (m != NULL) {
441 IF_PREPEND(&sc->outq, m);
442 break;
443 }
444 }
445
446 /* Call output process whether or not there is any output. We are
447 * being called in lieu of ttstart and must do what it would. */
448 if (tp->t_oproc != NULL)
449 (*tp->t_oproc) (tp);
450
451 /* This timeout is needed for operation on a pseudo-tty, because the
452 * pty code doesn't call pppstart after it has drained the t_outq. */
453 /* XXX: outq not locked */
454 if (!IFQ_IS_EMPTY(&sc->outq) && !callout_pending(&sc->chand))
455 ng_callout(&sc->chand, sc->node, NULL, 1, ngt_timeout, NULL, 0);
456
457 return (0);
458 }
459
460 /*
461 * We still have data to output to the device, so try sending more.
462 */
463 static void
464 ngt_timeout(node_p node, hook_p hook, void *arg1, int arg2)
465 {
466 const sc_p sc = NG_NODE_PRIVATE(node);
467
468 mtx_lock(&Giant);
469 ngt_start(sc->tp);
470 mtx_unlock(&Giant);
471 }
472
473 /******************************************************************
474 NETGRAPH NODE METHODS
475 ******************************************************************/
476
477 /*
478 * Initialize a new node of this type.
479 *
480 * We only allow nodes to be created as a result of setting
481 * the line discipline on a tty, so always return an error if not.
482 */
483 static int
484 ngt_constructor(node_p node)
485 {
486 return (EOPNOTSUPP);
487 }
488
489 /*
490 * Add a new hook. There can only be one.
491 */
492 static int
493 ngt_newhook(node_p node, hook_p hook, const char *name)
494 {
495 const sc_p sc = NG_NODE_PRIVATE(node);
496
497 if (strcmp(name, NG_TTY_HOOK))
498 return (EINVAL);
499
500 if (sc->hook)
501 return (EISCONN);
502
503 NGTLOCK(sc);
504 sc->hook = hook;
505 NGTUNLOCK(sc);
506
507 return (0);
508 }
509
510 /*
511 * Set the hook into queueing mode (for outgoing packets),
512 * so that we wont deliver mbuf thru the whole graph holding
513 * tty locks.
514 */
515 static int
516 ngt_connect(hook_p hook)
517 {
518 NG_HOOK_FORCE_QUEUE(NG_HOOK_PEER(hook));
519 /*
520 * XXX: While ngt_start() is Giant-locked, queue incoming
521 * packets, too. Otherwise we acquire Giant holding some
522 * IP stack locks, e.g. divinp, and this makes WITNESS scream.
523 */
524 NG_HOOK_FORCE_QUEUE(hook);
525 return (0);
526 }
527
528 /*
529 * Disconnect the hook
530 */
531 static int
532 ngt_disconnect(hook_p hook)
533 {
534 const sc_p sc = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
535
536 if (hook != sc->hook)
537 panic(__func__);
538
539 NGTLOCK(sc);
540 sc->hook = NULL;
541 NGTUNLOCK(sc);
542
543 return (0);
544 }
545
546 /*
547 * Remove this node. The does the netgraph portion of the shutdown.
548 * This should only be called indirectly from ngt_close().
549 *
550 * tp->t_lsc is already NULL, so we should be protected from
551 * tty calls now.
552 */
553 static int
554 ngt_shutdown(node_p node)
555 {
556 const sc_p sc = NG_NODE_PRIVATE(node);
557
558 NGTLOCK(sc);
559 if (!(sc->flags & FLG_DIE)) {
560 NGTUNLOCK(sc);
561 return (EOPNOTSUPP);
562 }
563 NGTUNLOCK(sc);
564
565 /* Free resources */
566 _IF_DRAIN(&sc->outq);
567 mtx_destroy(&(sc)->outq.ifq_mtx);
568 m_freem(sc->m);
569 NG_NODE_UNREF(sc->node);
570 FREE(sc, M_NETGRAPH);
571
572 return (0);
573 }
574
575 /*
576 * Receive incoming data from netgraph system. Put it on our
577 * output queue and start output if necessary.
578 */
579 static int
580 ngt_rcvdata(hook_p hook, item_p item)
581 {
582 const sc_p sc = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
583 struct mbuf *m;
584 int qlen;
585
586 if (hook != sc->hook)
587 panic(__func__);
588
589 NGI_GET_M(item, m);
590 NG_FREE_ITEM(item);
591
592 IF_LOCK(&sc->outq);
593 if (_IF_QFULL(&sc->outq)) {
594 _IF_DROP(&sc->outq);
595 IF_UNLOCK(&sc->outq);
596 NG_FREE_M(m);
597 return (ENOBUFS);
598 }
599
600 _IF_ENQUEUE(&sc->outq, m);
601 qlen = sc->outq.ifq_len;
602 IF_UNLOCK(&sc->outq);
603
604 /*
605 * If qlen > 1, then we should already have a scheduled callout.
606 */
607 if (qlen == 1) {
608 mtx_lock(&Giant);
609 ngt_start(sc->tp);
610 mtx_unlock(&Giant);
611 }
612
613 return (0);
614 }
615
616 /*
617 * Receive control message
618 */
619 static int
620 ngt_rcvmsg(node_p node, item_p item, hook_p lasthook)
621 {
622 const sc_p sc = NG_NODE_PRIVATE(node);
623 struct ng_mesg *msg, *resp = NULL;
624 int error = 0;
625
626 NGI_GET_MSG(item, msg);
627 switch (msg->header.typecookie) {
628 case NGM_TTY_COOKIE:
629 switch (msg->header.cmd) {
630 case NGM_TTY_SET_HOTCHAR:
631 {
632 int hotchar;
633
634 if (msg->header.arglen != sizeof(int))
635 ERROUT(EINVAL);
636 hotchar = *((int *) msg->data);
637 if (hotchar != (u_char) hotchar && hotchar != -1)
638 ERROUT(EINVAL);
639 sc->hotchar = hotchar; /* race condition is OK */
640 break;
641 }
642 case NGM_TTY_GET_HOTCHAR:
643 NG_MKRESPONSE(resp, msg, sizeof(int), M_NOWAIT);
644 if (!resp)
645 ERROUT(ENOMEM);
646 /* Race condition here is OK */
647 *((int *) resp->data) = sc->hotchar;
648 break;
649 default:
650 ERROUT(EINVAL);
651 }
652 break;
653 default:
654 ERROUT(EINVAL);
655 }
656 done:
657 NG_RESPOND_MSG(error, node, item, resp);
658 NG_FREE_MSG(msg);
659 return (error);
660 }
661
662 /******************************************************************
663 INITIALIZATION
664 ******************************************************************/
665
666 /*
667 * Handle loading and unloading for this node type
668 */
669 static int
670 ngt_mod_event(module_t mod, int event, void *data)
671 {
672 int error = 0;
673
674 switch (event) {
675 case MOD_LOAD:
676
677 /* Register line discipline */
678 mtx_lock(&Giant);
679 if ((ngt_ldisc = ldisc_register(NETGRAPHDISC, &ngt_disc)) < 0) {
680 mtx_unlock(&Giant);
681 log(LOG_ERR, "%s: can't register line discipline",
682 __func__);
683 return (EIO);
684 }
685 mtx_unlock(&Giant);
686 break;
687
688 case MOD_UNLOAD:
689
690 /* Unregister line discipline */
691 mtx_lock(&Giant);
692 ldisc_deregister(ngt_ldisc);
693 mtx_unlock(&Giant);
694 break;
695
696 default:
697 error = EOPNOTSUPP;
698 break;
699 }
700 return (error);
701 }
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