3 * $Id: endpt.c,v 1.4 2004/04/08 01:36:25 mdw Exp $
5 * Generic endpoint abstraction
7 * (c) 1999 Straylight/Edgeware
10 /*----- Licensing notice --------------------------------------------------*
12 * This file is part of the `fw' port forwarder.
14 * `fw' is free software; you can redistribute it and/or modify
15 * it under the terms of the GNU General Public License as published by
16 * the Free Software Foundation; either version 2 of the License, or
17 * (at your option) any later version.
19 * `fw' is distributed in the hope that it will be useful,
20 * but WITHOUT ANY WARRANTY; without even the implied warranty of
21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
22 * GNU General Public License for more details.
24 * You should have received a copy of the GNU General Public License
25 * along with `fw'; if not, write to the Free Software Foundation,
26 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
29 /*----- Header files ------------------------------------------------------*/
38 #include <sys/types.h>
42 #include <mLib/alloc.h>
47 /*----- Data structures ---------------------------------------------------*/
49 /* --- Pairs of channels --- *
51 * Channels are always allocated and freed in pairs. It makes sense to keep
52 * the pair together. (It also wastes less memory.)
55 typedef struct chanpair {
56 struct chanpair *next;
60 /* --- The `private data structure' --- *
62 * This is called a @tango@ because it takes two (endpoints).
65 typedef struct tango {
66 struct tango *next, *prev; /* A big list of all tangos */
67 endpt *a, *b; /* The two endpoints */
68 unsigned s; /* State of the connection */
69 chanpair *c; /* The pair of channels */
75 /*----- Static variables --------------------------------------------------*/
77 static chanpair *chans = 0; /* List of spare channel pairs */
78 static tango *tangos = 0; /* List of tangos */
80 /*----- Main code ---------------------------------------------------------*/
82 /* --- @doneab@, @doneba@ --- *
84 * Arguments: @void *p@ = pointer to a tango block
88 * Use: Handles completion of a channel.
91 static void doneab(void *p)
95 t->b->ops->wclose(t->b);
100 static void doneba(void *p)
104 t->a->ops->wclose(t->a);
109 /* --- @endpt_kill@ --- *
111 * Arguments: @endpt *a@ = an endpoint
115 * Use: Kills an endpoint. If the endpoint is joined to another, the
116 * other endpoint is also killed, as is the connection between
117 * them (and that's the tricky bit).
120 void endpt_kill(endpt *a)
125 /* --- If the endpont is unconnected, just close it --- */
135 /* --- See whether to close channels --- *
137 * I'll only have opened channels if both things are files. Also, the
138 * channel from @b@ to @a@ will only be open if @b@ is not pending.
141 if (a->f & b->f & EPF_FILE) {
143 chan_close(&t->c->ab);
144 if (!(b->f & EPF_PENDING) && (t->s & EPS_BA))
145 chan_close(&t->c->ba);
150 /* --- Now just throw the endpoints and tango block away --- */
155 t->next->prev = t->prev;
157 t->prev->next = t->next;
163 /* --- @endpt_killall@ --- *
169 * Use: Destroys all current endpoint connections. Used when
173 void endpt_killall(void)
184 /* --- @endpt_join@ --- *
186 * Arguments: @endpt *a@ = pointer to first endpoint
187 * @endpt *b@ = pointer to second endpoint
191 * Use: Joins two endpoints together. It's OK to join endpoints
192 * which are already joined; in fact, the the right thing to do
193 * when your endpoint decides that it's not pending any more is
194 * to join it to its partner again.
197 void endpt_join(endpt *a, endpt *b)
201 /* --- If there is no tango yet, create one --- */
210 t->s = EPS_AB | EPS_BA;
217 /* --- If both endpoints are unfinished, leave them for a while --- */
219 if (a->f & b->f & EPF_PENDING)
222 /* --- At least one endpoint is ready --- *
224 * If both endpoints are files then I can speculatively create the
225 * channels, which will let data start flowing a bit. Otherwise, I'll just
226 * have to wait some more.
229 if ((a->f | b->f) & EPF_PENDING) {
231 /* --- Only be interested if both things are files --- */
233 if (!t->c && (a->f & b->f & EPF_FILE)) {
235 /* --- Allocate a pair of channels --- */
238 t->c = xmalloc(sizeof(*t->c));
244 /* --- Make @a@ the endpoint which is ready --- */
246 if (a->f & EPF_PENDING) {
251 /* --- Open one channel to read from @a@ --- */
253 chan_open(&t->c->ab, a->in->fd, -1, doneab, t);
258 /* --- Both endpoints are now ready --- *
260 * There are four cases to consider here.
265 * Neither endpoint is a file. I need to make a pair of pipes and tell
266 * both endpoints to attach to them. I can then close the pipes and
270 if (!((a->f | b->f) & EPF_FILE)) {
272 reffd *rab, *wab, *rba, *wba;
274 /* --- Create the pipes --- */
276 if (pipe(pab)) goto tidy_nofile_0;
277 if (pipe(pba)) goto tidy_nofile_1;
279 /* --- Attach reference counters --- */
281 rab = reffd_init(pab[0]); wab = reffd_init(pab[1]);
282 rba = reffd_init(pba[0]); wba = reffd_init(pba[1]);
283 a->ops->attach(a, rba, wab);
284 b->ops->attach(b, rab, wba);
285 REFFD_DEC(rab); REFFD_DEC(wab);
286 REFFD_DEC(rba); REFFD_DEC(wba);
289 /* --- Tidy up after a mess --- */
292 close(pab[0]); close(pab[1]);
297 t->next->prev = t->prev;
299 t->prev->next = t->next;
308 * One endpoint is a file, the other isn't. I just attach the other
309 * endpoint to the file and stand well back.
312 if ((a->f ^ b->f) & EPF_FILE) {
314 /* --- Let @a@ be the endpoint with the file --- */
316 if (b->f & EPF_FILE) {
321 /* --- Attach the non-file endpoint to the file and run away --- *
323 * Leave it as the non-file's responsibility to close the other endpoint
324 * when it's ready. It should also close itself at that time.
327 b->ops->attach(b, a->in, a->out);
330 t->next->prev = t->prev;
332 t->prev->next = t->next;
341 * Both endpoints are files and I have a partially created channel pair. I
342 * need to create the other channel and add a destination to the first one.
343 * In this case, @t->b@ is the endpoint which has just finished setting
349 chan_open(&t->c->ba, b->in->fd, a->out->fd, doneba, t);
350 chan_dest(&t->c->ab, b->out->fd);
356 * Both endpoints are files and I don't have a partially created channel
357 * pair. I need to allocate a channel pair and create both channels.
361 t->c = xmalloc(sizeof(*t->c));
366 chan_open(&t->c->ab, a->in->fd, b->out->fd, doneab, t);
367 chan_open(&t->c->ba, b->in->fd, a->out->fd, doneba, t);
371 /*----- That's all, folks -------------------------------------------------*/