1 /*
2 * (MPSAFE)
3 *
4 * ng_tty.c
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 1.7.2.3 2002/02/13 00:43:12 dillon 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 * NOTE: This node operates at spltty().
60 */
61
62 #include <sys/param.h>
63 #include <sys/systm.h>
64 #include <sys/kernel.h>
65 #include <sys/conf.h>
66 #include <sys/proc.h>
67 #include <sys/caps.h>
68 #include <sys/mbuf.h>
69 #include <sys/malloc.h>
70 #include <sys/fcntl.h>
71 #include <sys/tty.h>
72 #include <sys/ttycom.h>
73 #include <sys/syslog.h>
74 #include <sys/errno.h>
75
76 #include <netgraph/ng_message.h>
77 #include <netgraph/netgraph.h>
78 #include "ng_tty.h"
79
80 /* Misc defs */
81 #define MAX_MBUFQ 3 /* Max number of queued mbufs */
82 #define NGT_HIWATER 400 /* High water mark on output */
83
84 /* Per-node private info */
85 struct ngt_sc {
86 struct tty *tp; /* Terminal device */
87 node_p node; /* Netgraph node */
88 hook_p hook; /* Netgraph hook */
89 struct mbuf *m; /* Incoming data buffer */
90 struct mbuf *qhead, **qtail; /* Queue of outgoing mbuf's */
91 short qlen; /* Length of queue */
92 short hotchar; /* Hotchar, or -1 if none */
93 u_int flags; /* Flags */
94 struct callout ctimeout; /* See man timeout(9) */
95 };
96 typedef struct ngt_sc *sc_p;
97
98 /* Flags */
99 #define FLG_TIMEOUT 0x0001 /* A timeout is pending */
100 #define FLG_DEBUG 0x0002
101
102 /* Debugging */
103 #ifdef INVARIANTS
104 #define QUEUECHECK(sc) \
105 do { \
106 struct mbuf **mp; \
107 int k; \
108 \
109 for (k = 0, mp = &sc->qhead; \
110 k <= MAX_MBUFQ && *mp; \
111 k++, mp = &(*mp)->m_nextpkt); \
112 if (k != sc->qlen || k > MAX_MBUFQ || *mp || mp != sc->qtail) \
113 panic("%s: queue", __func__); \
114 } while (0)
115 #else
116 #define QUEUECHECK(sc) do {} while (0)
117 #endif
118
119 /* Line discipline methods */
120 static int ngt_open(cdev_t dev, struct tty *tp);
121 static int ngt_close(struct tty *tp, int flag);
122 static int ngt_read(struct tty *tp, struct uio *uio, int flag);
123 static int ngt_write(struct tty *tp, struct uio *uio, int flag);
124 static int ngt_tioctl(struct tty *tp,
125 u_long cmd, caddr_t data, int flag, struct ucred *cred);
126 static int ngt_input(int c, struct tty *tp);
127 static int ngt_start(struct tty *tp);
128
129 /* Netgraph methods */
130 static ng_constructor_t ngt_constructor;
131 static ng_rcvmsg_t ngt_rcvmsg;
132 static ng_shutdown_t ngt_shutdown;
133 static ng_newhook_t ngt_newhook;
134 static ng_rcvdata_t ngt_rcvdata;
135 static ng_disconnect_t ngt_disconnect;
136 static int ngt_mod_event(module_t mod, int event, void *data);
137
138 /* Other stuff */
139 static void ngt_timeout(void *arg);
140
141 #define ERROUT(x) do { error = (x); goto done; } while (0)
142
143 /* Line discipline descriptor */
144 static struct linesw ngt_disc = {
145 ngt_open,
146 ngt_close,
147 ngt_read,
148 ngt_write,
149 ngt_tioctl,
150 ngt_input,
151 ngt_start,
152 ttymodem,
153 NG_TTY_DFL_HOTCHAR /* XXX can't change this in serial driver */
154 };
155
156 /* Netgraph node type descriptor */
157 static struct ng_type typestruct = {
158 NG_VERSION,
159 NG_TTY_NODE_TYPE,
160 ngt_mod_event,
161 ngt_constructor,
162 ngt_rcvmsg,
163 ngt_shutdown,
164 ngt_newhook,
165 NULL,
166 NULL,
167 ngt_rcvdata,
168 ngt_rcvdata,
169 ngt_disconnect,
170 NULL
171 };
172 NETGRAPH_INIT(tty, &typestruct);
173
174 static int ngt_unit;
175 static int ngt_nodeop_ok; /* OK to create/remove node */
176 static int ngt_ldisc;
177
178 /******************************************************************
179 LINE DISCIPLINE METHODS
180 ******************************************************************/
181
182 /*
183 * Set our line discipline on the tty.
184 * Called from device open routine or ttioctl() at >= splsofttty()
185 */
186 static int
ngt_open(cdev_t dev,struct tty * tp)187 ngt_open(cdev_t dev, struct tty *tp)
188 {
189 char name[sizeof(NG_TTY_NODE_TYPE) + 8];
190 sc_p sc;
191 int error;
192
193 /* Super-user only */
194 if ((error = caps_priv_check_self(SYSCAP_RESTRICTEDROOT)))
195 return (error);
196 lwkt_gettoken(&tp->t_token);
197
198 /* Already installed? */
199 if (tp->t_line == NETGRAPHDISC) {
200 sc = (sc_p) tp->t_sc;
201 if (sc != NULL && sc->tp == tp)
202 goto done;
203 }
204
205 /* Initialize private struct */
206 sc = kmalloc(sizeof(*sc), M_NETGRAPH, M_WAITOK | M_ZERO);
207 sc->tp = tp;
208 sc->hotchar = NG_TTY_DFL_HOTCHAR;
209 sc->qtail = &sc->qhead;
210 QUEUECHECK(sc);
211 callout_init_mp(&sc->ctimeout);
212
213 /* Setup netgraph node */
214 ngt_nodeop_ok = 1;
215 error = ng_make_node_common(&typestruct, &sc->node);
216 ngt_nodeop_ok = 0;
217 if (error) {
218 kfree(sc, M_NETGRAPH);
219 goto done;
220 }
221 ksnprintf(name, sizeof(name), "%s%d", typestruct.name, ngt_unit++);
222
223 /* Set back pointers */
224 sc->node->private = sc;
225 tp->t_sc = (caddr_t) sc;
226
227 /* Assign node its name */
228 if ((error = ng_name_node(sc->node, name))) {
229 log(LOG_ERR, "%s: node name exists?\n", name);
230 ngt_nodeop_ok = 1;
231 ng_rmnode(sc->node);
232 ngt_nodeop_ok = 0;
233 goto done;
234 }
235
236 /*
237 * Pre-allocate cblocks to the an appropriate amount.
238 * I'm not sure what is appropriate.
239 */
240 ttyflush(tp, FREAD | FWRITE);
241 clist_alloc_cblocks(&tp->t_canq, 0);
242 clist_alloc_cblocks(&tp->t_rawq, 0);
243 clist_alloc_cblocks(&tp->t_outq, MLEN + NGT_HIWATER);
244
245 done:
246 /* Done */
247 lwkt_reltoken(&tp->t_token);
248 return (error);
249 }
250
251 /*
252 * Line specific close routine, called from device close routine
253 * and from ttioctl at >= splsofttty(). This causes the node to
254 * be destroyed as well.
255 */
256 static int
ngt_close(struct tty * tp,int flag)257 ngt_close(struct tty *tp, int flag)
258 {
259 const sc_p sc = (sc_p) tp->t_sc;
260
261 lwkt_gettoken(&tp->t_token);
262 ttyflush(tp, FREAD | FWRITE);
263 clist_free_cblocks(&tp->t_outq);
264 tp->t_line = 0;
265 if (sc != NULL) {
266 if (sc->flags & FLG_TIMEOUT) {
267 callout_stop(&sc->ctimeout);
268 sc->flags &= ~FLG_TIMEOUT;
269 }
270 ngt_nodeop_ok = 1;
271 ng_rmnode(sc->node);
272 ngt_nodeop_ok = 0;
273 tp->t_sc = NULL;
274 }
275 lwkt_reltoken(&tp->t_token);
276
277 return (0);
278 }
279
280 /*
281 * Once the device has been turned into a node, we don't allow reading.
282 */
283 static int
ngt_read(struct tty * tp,struct uio * uio,int flag)284 ngt_read(struct tty *tp, struct uio *uio, int flag)
285 {
286 return (EIO);
287 }
288
289 /*
290 * Once the device has been turned into a node, we don't allow writing.
291 */
292 static int
ngt_write(struct tty * tp,struct uio * uio,int flag)293 ngt_write(struct tty *tp, struct uio *uio, int flag)
294 {
295 return (EIO);
296 }
297
298 /*
299 * We implement the NGIOCGINFO ioctl() defined in ng_message.h.
300 */
301 static int
ngt_tioctl(struct tty * tp,u_long cmd,caddr_t data,int flag,struct ucred * cred)302 ngt_tioctl(struct tty *tp, u_long cmd, caddr_t data, int flag, struct ucred *cred)
303 {
304 const sc_p sc = (sc_p) tp->t_sc;
305 int error = 0;
306
307 lwkt_gettoken(&tp->t_token);
308
309 switch (cmd) {
310 case NGIOCGINFO:
311 {
312 struct nodeinfo *const ni = (struct nodeinfo *) data;
313 const node_p node = sc->node;
314
315 bzero(ni, sizeof(*ni));
316 if (node->name)
317 strncpy(ni->name, node->name, sizeof(ni->name) - 1);
318 strncpy(ni->type, node->type->name, sizeof(ni->type) - 1);
319 ni->id = (u_int32_t)(uintptr_t)node;
320 ni->hooks = node->numhooks;
321 break;
322 }
323 default:
324 ERROUT(ENOIOCTL);
325 }
326 done:
327 lwkt_reltoken(&tp->t_token);
328
329 return (error);
330 }
331
332 /*
333 * Receive data coming from the device. We get one character at
334 * a time, which is kindof silly.
335 * Only guaranteed to be at splsofttty() or spltty().
336 */
337 static int
ngt_input(int c,struct tty * tp)338 ngt_input(int c, struct tty *tp)
339 {
340 const sc_p sc = (sc_p) tp->t_sc;
341 const node_p node = sc ? sc->node : NULL;
342 struct mbuf *m;
343 int error = 0;
344
345 lwkt_gettoken(&tp->t_token);
346 if (!sc || tp != sc->tp) {
347 lwkt_reltoken(&tp->t_token);
348 return (0);
349 }
350 if (!sc->hook)
351 ERROUT(0);
352
353 /* Check for error conditions */
354 if ((tp->t_state & TS_CONNECTED) == 0) {
355 if (sc->flags & FLG_DEBUG)
356 log(LOG_DEBUG, "%s: no carrier\n", node->name);
357 ERROUT(0);
358 }
359 if (c & TTY_ERRORMASK) {
360 /* framing error or overrun on this char */
361 if (sc->flags & FLG_DEBUG)
362 log(LOG_DEBUG, "%s: line error %x\n",
363 node->name, c & TTY_ERRORMASK);
364 ERROUT(0);
365 }
366 c &= TTY_CHARMASK;
367
368 /* Get a new header mbuf if we need one */
369 if (!(m = sc->m)) {
370 MGETHDR(m, M_NOWAIT, MT_DATA);
371 if (!m) {
372 if (sc->flags & FLG_DEBUG)
373 log(LOG_ERR,
374 "%s: can't get mbuf\n", node->name);
375 ERROUT(ENOBUFS);
376 }
377 m->m_len = m->m_pkthdr.len = 0;
378 m->m_pkthdr.rcvif = NULL;
379 sc->m = m;
380 }
381
382 /* Add char to mbuf */
383 *mtod(m, u_char *) = c;
384 m->m_data++;
385 m->m_len++;
386 m->m_pkthdr.len++;
387
388 /* Ship off mbuf if it's time */
389 if (sc->hotchar == -1 || c == sc->hotchar || m->m_len >= MHLEN) {
390 m->m_data = m->m_pktdat;
391 error = ng_queue_data(sc->hook, m, NULL);
392 sc->m = NULL;
393 }
394 done:
395 lwkt_reltoken(&tp->t_token);
396
397 return (error);
398 }
399
400 /*
401 * This is called when the device driver is ready for more output.
402 * Called from tty system at splsofttty() or spltty().
403 * Also call from ngt_rcv_data() when a new mbuf is available for output.
404 */
405 static int
ngt_start(struct tty * tp)406 ngt_start(struct tty *tp)
407 {
408 const sc_p sc = (sc_p) tp->t_sc;
409
410 lwkt_gettoken(&tp->t_token);
411 while (tp->t_outq.c_cc < NGT_HIWATER) { /* XXX 2.2 specific ? */
412 struct mbuf *m = sc->qhead;
413
414 /* Remove first mbuf from queue */
415 if (!m)
416 break;
417 if ((sc->qhead = m->m_nextpkt) == NULL)
418 sc->qtail = &sc->qhead;
419 sc->qlen--;
420 QUEUECHECK(sc);
421
422 /* Send as much of it as possible */
423 while (m) {
424 int sent;
425
426 sent = m->m_len - clist_btoq(mtod(m, u_char *),
427 m->m_len, &tp->t_outq);
428 m->m_data += sent;
429 m->m_len -= sent;
430 if (m->m_len > 0)
431 break; /* device can't take no more */
432 m = m_free(m);
433 }
434
435 /* Put remainder of mbuf chain (if any) back on queue */
436 if (m) {
437 m->m_nextpkt = sc->qhead;
438 sc->qhead = m;
439 if (sc->qtail == &sc->qhead)
440 sc->qtail = &m->m_nextpkt;
441 sc->qlen++;
442 QUEUECHECK(sc);
443 break;
444 }
445 }
446
447 /* Call output process whether or not there is any output. We are
448 * being called in lieu of ttstart and must do what it would. */
449 if (tp->t_oproc != NULL)
450 (*tp->t_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 if (sc->qhead && (sc->flags & FLG_TIMEOUT) == 0) {
455 callout_reset(&sc->ctimeout, 1, ngt_timeout, sc);
456 sc->flags |= FLG_TIMEOUT;
457 }
458 lwkt_reltoken(&tp->t_token);
459
460 return (0);
461 }
462
463 /*
464 * We still have data to output to the device, so try sending more.
465 */
466 static void
ngt_timeout(void * arg)467 ngt_timeout(void *arg)
468 {
469 const sc_p sc = (sc_p) arg;
470 struct tty *tp = sc->tp;
471
472 lwkt_gettoken(&tp->t_token);
473 sc->flags &= ~FLG_TIMEOUT;
474 ngt_start(tp);
475 lwkt_reltoken(&tp->t_token);
476 }
477
478 /******************************************************************
479 NETGRAPH NODE METHODS
480 ******************************************************************/
481
482 /*
483 * Initialize a new node of this type.
484 *
485 * We only allow nodes to be created as a result of setting
486 * the line discipline on a tty, so always return an error if not.
487 */
488 static int
ngt_constructor(node_p * nodep)489 ngt_constructor(node_p *nodep)
490 {
491 if (!ngt_nodeop_ok)
492 return (EOPNOTSUPP);
493 return (ng_make_node_common(&typestruct, nodep));
494 }
495
496 /*
497 * Add a new hook. There can only be one.
498 */
499 static int
ngt_newhook(node_p node,hook_p hook,const char * name)500 ngt_newhook(node_p node, hook_p hook, const char *name)
501 {
502 const sc_p sc = node->private;
503 struct tty *tp = sc->tp;
504 int error = 0;
505
506 if (strcmp(name, NG_TTY_HOOK))
507 return (EINVAL);
508 lwkt_gettoken(&tp->t_token);
509 if (sc->hook)
510 ERROUT(EISCONN);
511 sc->hook = hook;
512 done:
513 lwkt_reltoken(&tp->t_token);
514
515 return (error);
516 }
517
518 /*
519 * Disconnect the hook
520 */
521 static int
ngt_disconnect(hook_p hook)522 ngt_disconnect(hook_p hook)
523 {
524 const sc_p sc = hook->node->private;
525 struct tty *tp = sc->tp;
526
527 lwkt_gettoken(&tp->t_token);
528 if (hook != sc->hook)
529 panic(__func__);
530 sc->hook = NULL;
531 m_freem(sc->m);
532 sc->m = NULL;
533 lwkt_reltoken(&tp->t_token);
534
535 return (0);
536 }
537
538 /*
539 * Remove this node. The does the netgraph portion of the shutdown.
540 * This should only be called indirectly from ngt_close().
541 */
542 static int
ngt_shutdown(node_p node)543 ngt_shutdown(node_p node)
544 {
545 const sc_p sc = node->private;
546 struct tty *tp = sc->tp;
547
548 if (!ngt_nodeop_ok)
549 return (EOPNOTSUPP);
550 lwkt_gettoken(&tp->t_token);
551 ng_unname(node);
552 ng_cutlinks(node);
553 node->private = NULL;
554 ng_unref(sc->node);
555 m_freem(sc->qhead);
556 m_freem(sc->m);
557 bzero(sc, sizeof(*sc));
558 kfree(sc, M_NETGRAPH);
559 lwkt_reltoken(&tp->t_token);
560
561 return (0);
562 }
563
564 /*
565 * Receive incoming data from netgraph system. Put it on our
566 * output queue and start output if necessary.
567 */
568 static int
ngt_rcvdata(hook_p hook,struct mbuf * m,meta_p meta)569 ngt_rcvdata(hook_p hook, struct mbuf *m, meta_p meta)
570 {
571 const sc_p sc = hook->node->private;
572 struct tty *tp = sc->tp;
573 int error = 0;
574
575 if (hook != sc->hook)
576 panic(__func__);
577 NG_FREE_META(meta);
578 lwkt_gettoken(&tp->t_token);
579 if (sc->qlen >= MAX_MBUFQ)
580 ERROUT(ENOBUFS);
581 m->m_nextpkt = NULL;
582 *sc->qtail = m;
583 sc->qtail = &m->m_nextpkt;
584 sc->qlen++;
585 QUEUECHECK(sc);
586 m = NULL;
587 if (sc->qlen == 1)
588 ngt_start(sc->tp);
589 done:
590 lwkt_reltoken(&tp->t_token);
591 if (m)
592 m_freem(m);
593 return (error);
594 }
595
596 /*
597 * Receive control message
598 */
599 static int
ngt_rcvmsg(node_p node,struct ng_mesg * msg,const char * retaddr,struct ng_mesg ** rptr)600 ngt_rcvmsg(node_p node, struct ng_mesg *msg, const char *retaddr,
601 struct ng_mesg **rptr)
602 {
603 const sc_p sc = (sc_p) node->private;
604 struct tty *tp = sc->tp;
605 struct ng_mesg *resp = NULL;
606 int error = 0;
607
608 lwkt_gettoken(&tp->t_token);
609 switch (msg->header.typecookie) {
610 case NGM_TTY_COOKIE:
611 switch (msg->header.cmd) {
612 case NGM_TTY_SET_HOTCHAR:
613 {
614 int hotchar;
615
616 if (msg->header.arglen != sizeof(int))
617 ERROUT(EINVAL);
618 hotchar = *((int *) msg->data);
619 if (hotchar != (u_char) hotchar && hotchar != -1)
620 ERROUT(EINVAL);
621 sc->hotchar = hotchar; /* race condition is OK */
622 break;
623 }
624 case NGM_TTY_GET_HOTCHAR:
625 NG_MKRESPONSE(resp, msg, sizeof(int), M_NOWAIT);
626 if (!resp)
627 ERROUT(ENOMEM);
628 /* Race condition here is OK */
629 *((int *) resp->data) = sc->hotchar;
630 break;
631 default:
632 ERROUT(EINVAL);
633 }
634 break;
635 default:
636 ERROUT(EINVAL);
637 }
638 if (rptr)
639 *rptr = resp;
640 else if (resp)
641 kfree(resp, M_NETGRAPH);
642
643 done:
644 kfree(msg, M_NETGRAPH);
645 lwkt_reltoken(&tp->t_token);
646
647 return (error);
648 }
649
650 /******************************************************************
651 INITIALIZATION
652 ******************************************************************/
653
654 /*
655 * Handle loading and unloading for this node type
656 */
657 static int
ngt_mod_event(module_t mod,int event,void * data)658 ngt_mod_event(module_t mod, int event, void *data)
659 {
660 /* struct ng_type *const type = data;*/
661 int error = 0;
662
663 switch (event) {
664 case MOD_LOAD:
665 /* Register line discipline */
666 if ((ngt_ldisc = ldisc_register(NETGRAPHDISC, &ngt_disc)) < 0) {
667 log(LOG_ERR, "%s: can't register line discipline",
668 __func__);
669 return (EIO);
670 }
671 break;
672
673 case MOD_UNLOAD:
674
675 /* Unregister line discipline */
676 ldisc_deregister(ngt_ldisc);
677 break;
678
679 default:
680 error = EOPNOTSUPP;
681 break;
682 }
683 return (error);
684 }
685