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 -------------------------------------------------*/