3 * $Id: endpt.c,v 1.1 1999/07/26 23:33:01 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 /*----- Revision history --------------------------------------------------*
32 * Revision 1.1 1999/07/26 23:33:01 mdw
33 * Infrastructure for the new design.
37 /*----- Header files ------------------------------------------------------*/
46 #include <sys/types.h>
53 /*----- Data structures ---------------------------------------------------*/
55 /* --- Pairs of channels --- *
57 * Channels are always allocated and freed in pairs. It makes sense to keep
58 * the pair together. (It also wastes less memory.)
61 typedef struct chanpair {
62 struct chanpair *next;
66 /* --- The `private data structure' --- *
68 * This is called a @tango@ because it takes two (endpoints).
71 typedef struct tango {
72 struct tango *next, *prev; /* A big list of all tangos */
73 endpt *a, *b; /* The two endpoints */
74 unsigned s; /* State of the connection */
75 chanpair *c; /* The pair of channels */
81 /*----- Static variables --------------------------------------------------*/
83 static chanpair *chans = 0; /* List of spare channel pairs */
84 static tango *tangos = 0; /* List of tangos */
86 /*----- Main code ---------------------------------------------------------*/
88 /* --- @doneab@, @doneba@ --- *
90 * Arguments: @void *p@ = pointer to a tango block
94 * Use: Handles completion of a channel.
97 static void doneab(void *p)
101 t->b->ops->wclose(t->b);
106 static void doneba(void *p)
110 t->a->ops->wclose(t->a);
115 /* --- @endpt_kill@ --- *
117 * Arguments: @endpt *a@ = an endpoint
121 * Use: Kills an endpoint. If the endpoint is joined to another, the
122 * other endpoint is also killed, as is the connection between
123 * them (and that's the tricky bit).
126 void endpt_kill(endpt *a)
131 /* --- If the endpont is unconnected, just close it --- */
141 /* --- See whether to close channels --- *
143 * I'll only have opened channels if both things are files. Also, the
144 * channel from @b@ to @a@ will only be open if @b@ is not pending.
147 if (a->f & b->f & EPF_FILE) {
149 chan_close(&t->c->ab);
150 if (!(b->f & EPF_PENDING) && (t->s & EPS_BA))
151 chan_close(&t->c->ba);
156 /* --- Now just throw the endpoints and tango block away --- */
161 t->next->prev = t->prev;
163 t->prev->next = t->next;
169 /* --- @endpt_killall@ --- *
175 * Use: Destroys all current endpoint connections. Used when
179 void endpt_killall(void)
190 /* --- @endpt_join@ --- *
192 * Arguments: @endpt *a@ = pointer to first endpoint
193 * @endpt *b@ = pointer to second endpoint
197 * Use: Joins two endpoints together. It's OK to join endpoints
198 * which are already joined; in fact, the the right thing to do
199 * when your endpoint decides that it's not pending any more is
200 * to join it to its partner again.
203 void endpt_join(endpt *a, endpt *b)
207 /* --- If there is no tango yet, create one --- */
216 t->s = EPS_AB | EPS_BA;
223 /* --- If both endpoints are unfinished, leave them for a while --- */
225 if (a->f & b->f & EPF_PENDING)
228 /* --- At least one endpoint is ready --- *
230 * If both endpoints are files then I can speculatively create the
231 * channels, which will let data start flowing a bit. Otherwise, I'll just
232 * have to wait some more.
235 if ((a->f | b->f) & EPF_PENDING) {
237 /* --- Only be interested if both things are files --- */
239 if (!t->c && (a->f & b->f & EPF_FILE)) {
241 /* --- Allocate a pair of channels --- */
244 t->c = xmalloc(sizeof(*t->c));
250 /* --- Make @a@ the endpoint which is ready --- */
252 if (a->f & EPF_PENDING) {
257 /* --- Open one channel to read from @a@ --- */
259 chan_open(&t->c->ab, a->in->fd, -1, doneab, t);
264 /* --- Both endpoints are now ready --- *
266 * There are four cases to consider here.
271 * Neither endpoint is a file. I need to make a pair of pipes and tell
272 * both endpoints to attach to them. I can then close the pipes and
276 if (!((a->f | b->f) & EPF_FILE)) {
278 reffd *rab, *wab, *rba, *wba;
280 /* --- Create the pipes --- */
282 if (pipe(pab)) goto tidy_nofile_0;
283 if (pipe(pba)) goto tidy_nofile_1;
285 /* --- Attach reference counters --- */
287 rab = reffd_init(pab[0]); wab = reffd_init(pab[1]);
288 rba = reffd_init(pba[0]); wba = reffd_init(pba[1]);
289 a->ops->attach(a, rba, wab);
290 b->ops->attach(b, rab, wba);
291 REFFD_DEC(rab); REFFD_DEC(wab);
292 REFFD_DEC(rba); REFFD_DEC(wba);
295 /* --- Tidy up after a mess --- */
298 close(pab[0]); close(pab[1]);
303 t->next->prev = t->prev;
305 t->prev->next = t->next;
314 * One endpoint is a file, the other isn't. I just attach the other
315 * endpoint to the file and stand well back.
318 if ((a->f ^ b->f) & EPF_FILE) {
320 /* --- Let @a@ be the endpoint with the file --- */
322 if (b->f & EPF_FILE) {
327 /* --- Attach the non-file endpoint to the file and run away --- */
329 b->ops->attach(b, a->in, a->out);
333 t->next->prev = t->prev;
335 t->prev->next = t->next;
344 * Both endpoints are files and I have a partially created channel pair. I
345 * need to create the other channel and add a destination to the first one.
346 * In this case, @t->b@ is the endpoint which has just finished setting
352 chan_open(&t->c->ba, b->in->fd, a->out->fd, doneba, t);
353 chan_dest(&t->c->ab, b->out->fd);
359 * Both endpoints are files and I don't have a partially created channel
360 * pair. I need to allocate a channel pair and create both channels.
364 t->c = xmalloc(sizeof(*t->c));
369 chan_open(&t->c->ab, a->in->fd, b->out->fd, doneab, t);
370 chan_open(&t->c->ba, b->in->fd, a->out->fd, doneba, t);
374 /*----- That's all, folks -------------------------------------------------*/