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38 * Author: Archie Cobbs <archie@freebsd.org>
40 * $FreeBSD: src/sys/netgraph/ng_tty.c,v 1.37 2006/11/06 13:42:03 rwatson Exp $
41 * $Whistle: ng_tty.c,v 1.21 1999/11/01 09:24:52 julian Exp $
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.
50 * Once the line discipline is installed, you can find out the name
51 * of the corresponding netgraph node via a NGIOCGINFO ioctl().
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.
60 #include <sys/param.h>
61 #include <sys/systm.h>
63 #include <sys/errno.h>
64 #include <sys/fcntl.h>
65 #include <sys/kernel.h>
66 #include <sys/malloc.h>
69 #include <sys/socket.h>
70 #include <sys/syslog.h>
72 #include <sys/ttycom.h>
75 #include <net/if_var.h>
77 #include <netgraph7/netgraph.h>
78 #include <netgraph7/ng_message.h>
82 #define MAX_MBUFQ 3 /* Max number of queued mbufs */
83 #define NGT_HIWATER 400 /* High water mark on output */
85 /* Per-node private info */
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) */
96 typedef struct ngt_sc *sc_p;
99 #define FLG_DEBUG 0x0002
100 #define FLG_DIE 0x0004
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 ucred *cred);
109 static int ngt_input(int c, struct tty *tp);
110 static int ngt_start(struct tty *tp);
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);
123 static void ngt_timeout(node_p node, hook_p hook, void *arg1, int arg2);
125 #define ERROUT(x) do { error = (x); goto done; } while (0)
127 /* Line discipline descriptor */
128 static struct linesw ngt_disc = {
130 .l_close = ngt_close,
132 .l_write = ngt_write,
133 .l_ioctl = ngt_tioctl,
135 .l_start = ngt_start,
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,
152 NETGRAPH_INIT(tty, &typestruct);
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
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).
166 * - ngt_unit is incremented atomically.
170 static int ngt_ldisc;
172 /******************************************************************
173 LINE DISCIPLINE METHODS
174 ******************************************************************/
177 * Set our line discipline on the tty.
178 * Called from device open routine or ttioctl()
181 ngt_open(struct cdev *dev, struct tty *tp)
183 struct thread *const td = curthread; /* XXX */
184 char name[sizeof(NG_TTY_NODE_TYPE) + 8];
188 /* Super-user only */
189 error = priv_check(td, PRIV_NETGRAPH_TTY);
193 /* Initialize private struct */
194 sc = kmalloc(sizeof(*sc), M_NETGRAPH, M_WAITOK | M_ZERO);
196 lwkt_gettoken(&tp->t_token);
198 sc->hotchar = NG_TTY_DFL_HOTCHAR;
199 sc->outq.ifq_maxlen = MAX_MBUFQ;
201 /* Setup netgraph node */
202 error = ng_make_node_common(&typestruct, &sc->node);
204 kfree(sc, M_NETGRAPH);
205 lwkt_reltoken(&tp->t_token);
209 atomic_add_int(&ngt_unit, 1);
210 ksnprintf(name, sizeof(name), "%s%d", typestruct.name, ngt_unit);
212 /* Assign node its name */
213 if ((error = ng_name_node(sc->node, name))) {
214 sc->flags |= FLG_DIE;
215 NG_NODE_UNREF(sc->node);
216 log(LOG_ERR, "%s: node name exists?\n", name);
217 lwkt_reltoken(&tp->t_token);
221 /* Set back pointers */
222 NG_NODE_SET_PRIVATE(sc->node, sc);
225 callout_init_mp(&sc->chand);
228 * Pre-allocate cblocks to the an appropriate amount.
229 * I'm not sure what is appropriate.
231 ttyflush(tp, FREAD | FWRITE);
232 clist_alloc_cblocks(&tp->t_canq, 0, 0);
233 clist_alloc_cblocks(&tp->t_rawq, 0, 0);
234 clist_alloc_cblocks(&tp->t_outq,
235 MLEN + NGT_HIWATER, MLEN + NGT_HIWATER);
237 lwkt_reltoken(&tp->t_token);
242 * Line specific close routine, called from device close routine
243 * and from ttioctl. This causes the node to be destroyed as well.
246 ngt_close(struct tty *tp, int flag)
248 const sc_p sc = (sc_p) tp->t_sc;
250 lwkt_gettoken(&tp->t_token);
251 ttyflush(tp, FREAD | FWRITE);
252 clist_free_cblocks(&tp->t_outq);
254 if (callout_pending(&sc->chand))
255 ng_uncallout(&sc->chand, sc->node);
257 sc->flags |= FLG_DIE;
258 ng_rmnode_self(sc->node);
260 lwkt_reltoken(&tp->t_token);
265 * Once the device has been turned into a node, we don't allow reading.
268 ngt_read(struct tty *tp, struct uio *uio, int flag)
274 * Once the device has been turned into a node, we don't allow writing.
277 ngt_write(struct tty *tp, struct uio *uio, int flag)
283 * We implement the NGIOCGINFO ioctl() defined in ng_message.h.
286 ngt_tioctl(struct tty *tp, u_long cmd, caddr_t data, int flag, struct ucred *cred)
288 const sc_p sc = (sc_p) tp->t_sc;
291 /* No node attached */
295 lwkt_gettoken(&tp->t_token);
299 struct nodeinfo *const ni = (struct nodeinfo *) data;
300 const node_p node = sc->node;
302 bzero(ni, sizeof(*ni));
303 if (NG_NODE_HAS_NAME(node))
304 strncpy(ni->name, NG_NODE_NAME(node), sizeof(ni->name) - 1);
305 strncpy(ni->type, node->nd_type->name, sizeof(ni->type) - 1);
306 ni->id = (u_int32_t) ng_node2ID(node);
307 ni->hooks = NG_NODE_NUMHOOKS(node);
311 lwkt_reltoken(&tp->t_token);
315 lwkt_reltoken(&tp->t_token);
320 * Receive data coming from the device. We get one character at
321 * a time, which is kindof silly.
323 * Full locking of softc is not required, since we are the only
327 ngt_input(int c, struct tty *tp)
334 lwkt_gettoken(&tp->t_token);
335 sc = (sc_p) tp->t_sc;
337 /* No node attached */
338 lwkt_reltoken(&tp->t_token);
347 /* Check for error conditions */
348 if ((tp->t_state & TS_CONNECTED) == 0) {
349 if (sc->flags & FLG_DEBUG)
350 log(LOG_DEBUG, "%s: no carrier\n", NG_NODE_NAME(node));
351 lwkt_reltoken(&tp->t_token);
354 if (c & TTY_ERRORMASK) {
355 /* framing error or overrun on this char */
356 if (sc->flags & FLG_DEBUG)
357 log(LOG_DEBUG, "%s: line error %x\n",
358 NG_NODE_NAME(node), c & TTY_ERRORMASK);
359 lwkt_reltoken(&tp->t_token);
364 /* Get a new header mbuf if we need one */
366 MGETHDR(m, M_NOWAIT, MT_DATA);
368 if (sc->flags & FLG_DEBUG)
370 "%s: can't get mbuf\n", NG_NODE_NAME(node));
371 lwkt_reltoken(&tp->t_token);
374 m->m_len = m->m_pkthdr.len = 0;
375 m->m_pkthdr.rcvif = NULL;
379 /* Add char to mbuf */
380 *mtod(m, u_char *) = c;
385 /* Ship off mbuf if it's time */
386 if (sc->hotchar == -1 || c == sc->hotchar || m->m_len >= MHLEN) {
387 m->m_data = m->m_pktdat;
391 * We have built our mbuf without checking that we actually
392 * have a hook to send it. This was done to avoid
393 * acquiring mutex on each character. Check now.
397 if (sc->hook == NULL) {
399 lwkt_reltoken(&tp->t_token);
400 return (0); /* XXX: original behavior */
402 NG_SEND_DATA_ONLY(error, sc->hook, m); /* Will queue */
405 lwkt_reltoken(&tp->t_token);
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.
414 ngt_start(struct tty *tp)
416 const sc_p sc = (sc_p) tp->t_sc;
418 lwkt_gettoken(&tp->t_token);
419 while (tp->t_outq.c_cc < NGT_HIWATER) { /* XXX 2.2 specific ? */
422 /* Remove first mbuf from queue */
423 IF_DEQUEUE(&sc->outq, m);
427 /* Send as much of it as possible */
432 - b_to_q(mtod(m, u_char *), m->m_len, &tp->t_outq);
436 break; /* device can't take no more */
440 /* Put remainder of mbuf chain (if any) back on queue */
442 IF_PREPEND(&sc->outq, m);
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)
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 (!IF_QEMPTY(&sc->outq) && !callout_pending(&sc->chand))
456 ng_callout(&sc->chand, sc->node, NULL, 1, ngt_timeout, NULL, 0);
458 lwkt_reltoken(&tp->t_token);
463 * We still have data to output to the device, so try sending more.
466 ngt_timeout(node_p node, hook_p hook, void *arg1, int arg2)
468 const sc_p sc = NG_NODE_PRIVATE(node);
469 struct tty *tp = sc->tp;
471 lwkt_gettoken(&tp->t_token);
473 lwkt_reltoken(&tp->t_token);
476 /******************************************************************
477 NETGRAPH NODE METHODS
478 ******************************************************************/
481 * Initialize a new node of this type.
483 * We only allow nodes to be created as a result of setting
484 * the line discipline on a tty, so always return an error if not.
487 ngt_constructor(node_p node)
493 * Add a new hook. There can only be one.
496 ngt_newhook(node_p node, hook_p hook, const char *name)
498 const sc_p sc = NG_NODE_PRIVATE(node);
499 struct tty *tp = sc->tp;
501 if (strcmp(name, NG_TTY_HOOK))
503 lwkt_gettoken(&tp->t_token);
505 lwkt_reltoken(&tp->t_token);
509 lwkt_reltoken(&tp->t_token);
514 * Set the hook into queueing mode (for outgoing packets),
515 * so that we wont deliver mbuf thru the whole graph holding
519 ngt_connect(hook_p hook)
521 NG_HOOK_FORCE_QUEUE(NG_HOOK_PEER(hook));
523 * XXX: While ngt_start() is Giant-locked, queue incoming
524 * packets, too. Otherwise we acquire Giant holding some
525 * IP stack locks, e.g. divinp, and this makes WITNESS scream.
527 NG_HOOK_FORCE_QUEUE(hook);
532 * Disconnect the hook
535 ngt_disconnect(hook_p hook)
537 const sc_p sc = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
538 struct tty *tp = sc->tp;
540 lwkt_gettoken(&tp->t_token);
541 if (hook != sc->hook)
544 lwkt_reltoken(&tp->t_token);
549 * Remove this node. The does the netgraph portion of the shutdown.
550 * This should only be called indirectly from ngt_close().
552 * tp->t_lsc is already NULL, so we should be protected from
556 ngt_shutdown(node_p node)
558 const sc_p sc = NG_NODE_PRIVATE(node);
559 struct tty *tp = sc->tp;
561 lwkt_gettoken(&tp->t_token);
562 if (!(sc->flags & FLG_DIE)) {
563 lwkt_reltoken(&tp->t_token);
570 kfree(sc, M_NETGRAPH);
571 lwkt_reltoken(&tp->t_token);
576 * Receive incoming data from netgraph system. Put it on our
577 * output queue and start output if necessary.
580 ngt_rcvdata(hook_p hook, item_p item)
582 const sc_p sc = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
583 struct tty *tp = sc->tp;
587 if (hook != sc->hook)
593 if (IF_QFULL(&sc->outq)) {
599 IF_ENQUEUE(&sc->outq, m);
600 qlen = sc->outq.ifq_len;
603 * If qlen > 1, then we should already have a scheduled callout.
606 lwkt_gettoken(&tp->t_token);
608 lwkt_reltoken(&tp->t_token);
615 * Receive control message
618 ngt_rcvmsg(node_p node, item_p item, hook_p lasthook)
620 const sc_p sc = NG_NODE_PRIVATE(node);
621 struct ng_mesg *msg, *resp = NULL;
624 NGI_GET_MSG(item, msg);
625 switch (msg->header.typecookie) {
627 switch (msg->header.cmd) {
628 case NGM_TTY_SET_HOTCHAR:
632 if (msg->header.arglen != sizeof(int))
634 hotchar = *((int *) msg->data);
635 if (hotchar != (u_char) hotchar && hotchar != -1)
637 sc->hotchar = hotchar; /* race condition is OK */
640 case NGM_TTY_GET_HOTCHAR:
641 NG_MKRESPONSE(resp, msg, sizeof(int), M_WAITOK | M_NULLOK);
644 /* Race condition here is OK */
645 *((int *) resp->data) = sc->hotchar;
655 NG_RESPOND_MSG(error, node, item, resp);
660 /******************************************************************
662 ******************************************************************/
665 * Handle loading and unloading for this node type
668 ngt_mod_event(module_t mod, int event, void *data)
674 /* Register line discipline */
675 if ((ngt_ldisc = ldisc_register(NETGRAPHDISC, &ngt_disc)) < 0) {
676 log(LOG_ERR, "%s: can't register line discipline",
684 /* Unregister line discipline */
685 ldisc_deregister(ngt_ldisc);