3 * Generic endpoint abstraction
5 * (c) 1999 Straylight/Edgeware
8 /*----- Licensing notice --------------------------------------------------*
10 * This file is part of the `fw' port forwarder.
12 * `fw' is free software; you can redistribute it and/or modify
13 * it under the terms of the GNU General Public License as published by
14 * the Free Software Foundation; either version 2 of the License, or
15 * (at your option) any later version.
17 * `fw' is distributed in the hope that it will be useful,
18 * but WITHOUT ANY WARRANTY; without even the implied warranty of
19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20 * GNU General Public License for more details.
22 * You should have received a copy of the GNU General Public License
23 * along with `fw'; if not, write to the Free Software Foundation,
24 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
29 /*----- Data structures ---------------------------------------------------*/
31 /* --- Pairs of channels --- *
33 * Channels are always allocated and freed in pairs. It makes sense to keep
34 * the pair together. (It also wastes less memory.)
37 typedef struct chanpair
{
38 struct chanpair
*next
;
42 /* --- The `private data structure' --- *
44 * This is called a @tango@ because it takes two (endpoints).
47 typedef struct tango
{
48 struct tango
*next
, *prev
; /* A big list of all tangos */
49 endpt
*a
, *b
; /* The two endpoints */
50 unsigned s
; /* State of the connection */
51 chanpair
*c
; /* The pair of channels */
57 /*----- Static variables --------------------------------------------------*/
59 static chanpair
*chans
= 0; /* List of spare channel pairs */
60 static tango
*tangos
= 0; /* List of tangos */
62 /*----- Main code ---------------------------------------------------------*/
64 /* --- @doneab@, @doneba@ --- *
66 * Arguments: @void *p@ = pointer to a tango block
70 * Use: Handles completion of a channel.
73 static void doneab(void *p
)
77 t
->b
->ops
->wclose(t
->b
);
82 static void doneba(void *p
)
86 t
->a
->ops
->wclose(t
->a
);
91 /* --- @endpt_kill@ --- *
93 * Arguments: @endpt *a@ = an endpoint
97 * Use: Kills an endpoint. If the endpoint is joined to another, the
98 * other endpoint is also killed, as is the connection between
99 * them (and that's the tricky bit).
102 void endpt_kill(endpt
*a
)
107 /* --- If the endpont is unconnected, just close it --- */
117 /* --- See whether to close channels --- *
119 * I'll only have opened channels if both things are files. Also, the
120 * channel from @b@ to @a@ will only be open if @b@ is not pending.
123 if (a
->f
& b
->f
& EPF_FILE
) {
125 chan_close(&t
->c
->ab
);
126 if (!(b
->f
& EPF_PENDING
) && (t
->s
& EPS_BA
))
127 chan_close(&t
->c
->ba
);
132 /* --- Now just throw the endpoints and tango block away --- */
137 t
->next
->prev
= t
->prev
;
139 t
->prev
->next
= t
->next
;
145 /* --- @endpt_killall@ --- *
151 * Use: Destroys all current endpoint connections. Used when
155 void endpt_killall(void)
166 /* --- @endpt_join@ --- *
168 * Arguments: @endpt *a@ = pointer to first endpoint
169 * @endpt *b@ = pointer to second endpoint
173 * Use: Joins two endpoints together. It's OK to join endpoints
174 * which are already joined; in fact, the the right thing to do
175 * when your endpoint decides that it's not pending any more is
176 * to join it to its partner again.
179 void endpt_join(endpt
*a
, endpt
*b
)
183 /* --- If there is no tango yet, create one --- */
192 t
->s
= EPS_AB
| EPS_BA
;
199 /* --- If both endpoints are unfinished, leave them for a while --- */
201 if (a
->f
& b
->f
& EPF_PENDING
)
204 /* --- At least one endpoint is ready --- *
206 * If both endpoints are files then I can speculatively create the
207 * channels, which will let data start flowing a bit. Otherwise, I'll just
208 * have to wait some more.
211 if ((a
->f
| b
->f
) & EPF_PENDING
) {
213 /* --- Only be interested if both things are files --- */
215 if (!t
->c
&& (a
->f
& b
->f
& EPF_FILE
)) {
217 /* --- Allocate a pair of channels --- */
220 t
->c
= xmalloc(sizeof(*t
->c
));
226 /* --- Make @a@ the endpoint which is ready --- */
228 if (a
->f
& EPF_PENDING
) {
233 /* --- Open one channel to read from @a@ --- */
235 chan_open(&t
->c
->ab
, a
->in
->fd
, -1, doneab
, t
);
240 /* --- Both endpoints are now ready --- *
242 * There are four cases to consider here.
247 * Neither endpoint is a file. I need to make a pair of pipes and tell
248 * both endpoints to attach to them. I can then close the pipes and
252 if (!((a
->f
| b
->f
) & EPF_FILE
)) {
254 reffd
*rab
, *wab
, *rba
, *wba
;
256 /* --- Create the pipes --- */
258 if (pipe(pab
)) goto tidy_nofile_0
;
259 if (pipe(pba
)) goto tidy_nofile_1
;
261 /* --- Attach reference counters --- */
263 rab
= reffd_init(pab
[0]); wab
= reffd_init(pab
[1]);
264 rba
= reffd_init(pba
[0]); wba
= reffd_init(pba
[1]);
265 a
->ops
->attach(a
, rba
, wab
);
266 b
->ops
->attach(b
, rab
, wba
);
267 REFFD_DEC(rab
); REFFD_DEC(wab
);
268 REFFD_DEC(rba
); REFFD_DEC(wba
);
271 /* --- Tidy up after a mess --- */
274 close(pab
[0]); close(pab
[1]);
279 t
->next
->prev
= t
->prev
;
281 t
->prev
->next
= t
->next
;
290 * One endpoint is a file, the other isn't. I just attach the other
291 * endpoint to the file and stand well back.
294 if ((a
->f
^ b
->f
) & EPF_FILE
) {
296 /* --- Let @a@ be the endpoint with the file --- */
298 if (b
->f
& EPF_FILE
) {
303 /* --- Attach the non-file endpoint to the file and run away --- *
305 * Leave it as the non-file's responsibility to close the other endpoint
306 * when it's ready. It should also close itself at that time.
309 b
->ops
->attach(b
, a
->in
, a
->out
);
312 t
->next
->prev
= t
->prev
;
314 t
->prev
->next
= t
->next
;
323 * Both endpoints are files and I have a partially created channel pair. I
324 * need to create the other channel and add a destination to the first one.
325 * In this case, @t->b@ is the endpoint which has just finished setting
331 chan_open(&t
->c
->ba
, b
->in
->fd
, a
->out
->fd
, doneba
, t
);
332 chan_dest(&t
->c
->ab
, b
->out
->fd
);
338 * Both endpoints are files and I don't have a partially created channel
339 * pair. I need to allocate a channel pair and create both channels.
343 t
->c
= xmalloc(sizeof(*t
->c
));
348 chan_open(&t
->c
->ab
, a
->in
->fd
, b
->out
->fd
, doneab
, t
);
349 chan_open(&t
->c
->ba
, b
->in
->fd
, a
->out
->fd
, doneba
, t
);
353 /*----- That's all, folks -------------------------------------------------*/