07d71f34 |
1 | /* -*-c-*- |
2 | * |
28d2517c |
3 | * $Id: endpt.c,v 1.2 1999/10/22 22:46:17 mdw Exp $ |
07d71f34 |
4 | * |
5 | * Generic endpoint abstraction |
6 | * |
7 | * (c) 1999 Straylight/Edgeware |
8 | */ |
9 | |
10 | /*----- Licensing notice --------------------------------------------------* |
11 | * |
12 | * This file is part of the `fw' port forwarder. |
13 | * |
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. |
18 | * |
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. |
23 | * |
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. |
27 | */ |
28 | |
29 | /*----- Revision history --------------------------------------------------* |
30 | * |
31 | * $Log: endpt.c,v $ |
28d2517c |
32 | * Revision 1.2 1999/10/22 22:46:17 mdw |
33 | * When a non-file endpoint is attached to a file, keep the file endpoint |
34 | * open until the nonfile is done. This stops socket sources from |
35 | * resetting their connection limits too early. |
36 | * |
07d71f34 |
37 | * Revision 1.1 1999/07/26 23:33:01 mdw |
38 | * Infrastructure for the new design. |
39 | * |
40 | */ |
41 | |
42 | /*----- Header files ------------------------------------------------------*/ |
43 | |
44 | #include "config.h" |
45 | |
46 | #include <errno.h> |
47 | #include <stdio.h> |
48 | #include <stdlib.h> |
49 | #include <string.h> |
50 | |
51 | #include <sys/types.h> |
52 | #include <unistd.h> |
53 | #include <fcntl.h> |
54 | |
55 | #include "chan.h" |
56 | #include "endpt.h" |
57 | |
58 | /*----- Data structures ---------------------------------------------------*/ |
59 | |
60 | /* --- Pairs of channels --- * |
61 | * |
62 | * Channels are always allocated and freed in pairs. It makes sense to keep |
63 | * the pair together. (It also wastes less memory.) |
64 | */ |
65 | |
66 | typedef struct chanpair { |
67 | struct chanpair *next; |
68 | chan ab, ba; |
69 | } chanpair; |
70 | |
71 | /* --- The `private data structure' --- * |
72 | * |
73 | * This is called a @tango@ because it takes two (endpoints). |
74 | */ |
75 | |
76 | typedef struct tango { |
77 | struct tango *next, *prev; /* A big list of all tangos */ |
78 | endpt *a, *b; /* The two endpoints */ |
79 | unsigned s; /* State of the connection */ |
80 | chanpair *c; /* The pair of channels */ |
81 | } tango; |
82 | |
83 | #define EPS_AB 1u |
84 | #define EPS_BA 2u |
85 | |
86 | /*----- Static variables --------------------------------------------------*/ |
87 | |
88 | static chanpair *chans = 0; /* List of spare channel pairs */ |
89 | static tango *tangos = 0; /* List of tangos */ |
90 | |
91 | /*----- Main code ---------------------------------------------------------*/ |
92 | |
93 | /* --- @doneab@, @doneba@ --- * |
94 | * |
95 | * Arguments: @void *p@ = pointer to a tango block |
96 | * |
97 | * Returns: --- |
98 | * |
99 | * Use: Handles completion of a channel. |
100 | */ |
101 | |
102 | static void doneab(void *p) |
103 | { |
104 | tango *t = p; |
105 | t->s &= ~EPS_AB; |
106 | t->b->ops->wclose(t->b); |
107 | if (!t->s) |
108 | endpt_kill(t->a); |
109 | } |
110 | |
111 | static void doneba(void *p) |
112 | { |
113 | tango *t = p; |
114 | t->s &= ~EPS_BA; |
115 | t->a->ops->wclose(t->a); |
116 | if (!t->s) |
117 | endpt_kill(t->a); |
118 | } |
119 | |
120 | /* --- @endpt_kill@ --- * |
121 | * |
122 | * Arguments: @endpt *a@ = an endpoint |
123 | * |
124 | * Returns: --- |
125 | * |
126 | * Use: Kills an endpoint. If the endpoint is joined to another, the |
127 | * other endpoint is also killed, as is the connection between |
128 | * them (and that's the tricky bit). |
129 | */ |
130 | |
131 | void endpt_kill(endpt *a) |
132 | { |
133 | tango *t; |
134 | endpt *b; |
135 | |
136 | /* --- If the endpont is unconnected, just close it --- */ |
137 | |
138 | if (!a->t) { |
139 | a->ops->close(a); |
140 | return; |
141 | } |
142 | t = a->t; |
143 | a = t->a; |
144 | b = t->b; |
145 | |
146 | /* --- See whether to close channels --- * |
147 | * |
148 | * I'll only have opened channels if both things are files. Also, the |
149 | * channel from @b@ to @a@ will only be open if @b@ is not pending. |
150 | */ |
151 | |
152 | if (a->f & b->f & EPF_FILE) { |
153 | if (t->s & EPS_AB) |
154 | chan_close(&t->c->ab); |
155 | if (!(b->f & EPF_PENDING) && (t->s & EPS_BA)) |
156 | chan_close(&t->c->ba); |
157 | t->c->next = chans; |
158 | chans = t->c; |
159 | } |
160 | |
161 | /* --- Now just throw the endpoints and tango block away --- */ |
162 | |
163 | a->ops->close(a); |
164 | b->ops->close(b); |
165 | if (t->next) |
166 | t->next->prev = t->prev; |
167 | if (t->prev) |
168 | t->prev->next = t->next; |
169 | else |
170 | tangos = t->next; |
171 | DESTROY(t); |
172 | } |
173 | |
174 | /* --- @endpt_killall@ --- * |
175 | * |
176 | * Arguments: --- |
177 | * |
178 | * Returns: --- |
179 | * |
180 | * Use: Destroys all current endpoint connections. Used when |
181 | * shutting down. |
182 | */ |
183 | |
184 | void endpt_killall(void) |
185 | { |
186 | tango *t = tangos; |
187 | while (t) { |
188 | tango *tt = t; |
189 | t = t->next; |
190 | endpt_kill(tt->a); |
191 | } |
192 | tangos = 0; |
193 | } |
194 | |
195 | /* --- @endpt_join@ --- * |
196 | * |
197 | * Arguments: @endpt *a@ = pointer to first endpoint |
198 | * @endpt *b@ = pointer to second endpoint |
199 | * |
200 | * Returns: --- |
201 | * |
202 | * Use: Joins two endpoints together. It's OK to join endpoints |
203 | * which are already joined; in fact, the the right thing to do |
204 | * when your endpoint decides that it's not pending any more is |
205 | * to join it to its partner again. |
206 | */ |
207 | |
208 | void endpt_join(endpt *a, endpt *b) |
209 | { |
210 | tango *t = a->t; |
211 | |
212 | /* --- If there is no tango yet, create one --- */ |
213 | |
214 | if (!t) { |
215 | t = CREATE(tango); |
216 | t->next = tangos; |
217 | t->prev = 0; |
218 | t->a = b->other = a; |
219 | t->b = a->other = b; |
220 | a->t = b->t = t; |
221 | t->s = EPS_AB | EPS_BA; |
222 | t->c = 0; |
223 | if (tangos) |
224 | tangos->prev = t; |
225 | tangos = t; |
226 | } |
227 | |
228 | /* --- If both endpoints are unfinished, leave them for a while --- */ |
229 | |
230 | if (a->f & b->f & EPF_PENDING) |
231 | return; |
232 | |
233 | /* --- At least one endpoint is ready --- * |
234 | * |
235 | * If both endpoints are files then I can speculatively create the |
236 | * channels, which will let data start flowing a bit. Otherwise, I'll just |
237 | * have to wait some more. |
238 | */ |
239 | |
240 | if ((a->f | b->f) & EPF_PENDING) { |
241 | |
242 | /* --- Only be interested if both things are files --- */ |
243 | |
244 | if (!t->c && (a->f & b->f & EPF_FILE)) { |
245 | |
246 | /* --- Allocate a pair of channels --- */ |
247 | |
248 | if (!chans) |
249 | t->c = xmalloc(sizeof(*t->c)); |
250 | else { |
251 | t->c = chans; |
252 | chans = chans->next; |
253 | } |
254 | |
255 | /* --- Make @a@ the endpoint which is ready --- */ |
256 | |
257 | if (a->f & EPF_PENDING) { |
258 | t->b = a; t->a = b; |
259 | a = t->a; b = t->b; |
260 | } |
261 | |
262 | /* --- Open one channel to read from @a@ --- */ |
263 | |
264 | chan_open(&t->c->ab, a->in->fd, -1, doneab, t); |
265 | } |
266 | return; |
267 | } |
268 | |
269 | /* --- Both endpoints are now ready --- * |
270 | * |
271 | * There are four cases to consider here. |
272 | */ |
273 | |
274 | /* --- Case 1 --- * |
275 | * |
276 | * Neither endpoint is a file. I need to make a pair of pipes and tell |
277 | * both endpoints to attach to them. I can then close the pipes and |
278 | * discard the tango. |
279 | */ |
280 | |
281 | if (!((a->f | b->f) & EPF_FILE)) { |
282 | int pab[2], pba[2]; |
283 | reffd *rab, *wab, *rba, *wba; |
284 | |
285 | /* --- Create the pipes --- */ |
286 | |
287 | if (pipe(pab)) goto tidy_nofile_0; |
288 | if (pipe(pba)) goto tidy_nofile_1; |
289 | |
290 | /* --- Attach reference counters --- */ |
291 | |
292 | rab = reffd_init(pab[0]); wab = reffd_init(pab[1]); |
293 | rba = reffd_init(pba[0]); wba = reffd_init(pba[1]); |
294 | a->ops->attach(a, rba, wab); |
295 | b->ops->attach(b, rab, wba); |
296 | REFFD_DEC(rab); REFFD_DEC(wab); |
297 | REFFD_DEC(rba); REFFD_DEC(wba); |
298 | goto tidy_nofile_0; |
299 | |
300 | /* --- Tidy up after a mess --- */ |
301 | |
302 | tidy_nofile_1: |
303 | close(pab[0]); close(pab[1]); |
304 | tidy_nofile_0: |
305 | a->ops->close(a); |
306 | b->ops->close(b); |
307 | if (t->next) |
308 | t->next->prev = t->prev; |
309 | if (t->prev) |
310 | t->prev->next = t->next; |
311 | else |
312 | tangos = t->next; |
313 | DESTROY(t); |
314 | return; |
315 | } |
316 | |
317 | /* --- Case 2 --- * |
318 | * |
319 | * One endpoint is a file, the other isn't. I just attach the other |
320 | * endpoint to the file and stand well back. |
321 | */ |
322 | |
323 | if ((a->f ^ b->f) & EPF_FILE) { |
324 | |
325 | /* --- Let @a@ be the endpoint with the file --- */ |
326 | |
327 | if (b->f & EPF_FILE) { |
328 | endpt *e; |
329 | e = a; a = b; b = e; |
330 | } |
331 | |
28d2517c |
332 | /* --- Attach the non-file endpoint to the file and run away --- * |
333 | * |
334 | * Leave it as the non-file's responsibility to close the other endpoint |
335 | * when it's ready. It should also close itself at that time. |
336 | */ |
07d71f34 |
337 | |
338 | b->ops->attach(b, a->in, a->out); |
28d2517c |
339 | b->ops->file(b, a); |
07d71f34 |
340 | if (t->next) |
341 | t->next->prev = t->prev; |
342 | if (t->prev) |
343 | t->prev->next = t->next; |
344 | else |
345 | tangos = t->next; |
346 | DESTROY(t); |
347 | return; |
348 | } |
349 | |
350 | /* --- Case 3 --- * |
351 | * |
352 | * Both endpoints are files and I have a partially created channel pair. I |
353 | * need to create the other channel and add a destination to the first one. |
354 | * In this case, @t->b@ is the endpoint which has just finished setting |
355 | * itself up. |
356 | */ |
357 | |
358 | if (t->c) { |
359 | a = t->a; b = t->b; |
360 | chan_open(&t->c->ba, b->in->fd, a->out->fd, doneba, t); |
361 | chan_dest(&t->c->ab, b->out->fd); |
362 | return; |
363 | } |
364 | |
365 | /* --- Case 4 --- * |
366 | * |
367 | * Both endpoints are files and I don't have a partially created channel |
368 | * pair. I need to allocate a channel pair and create both channels. |
369 | */ |
370 | |
371 | if (!chans) |
372 | t->c = xmalloc(sizeof(*t->c)); |
373 | else { |
374 | t->c = chans; |
375 | chans = chans->next; |
376 | } |
377 | chan_open(&t->c->ab, a->in->fd, b->out->fd, doneab, t); |
378 | chan_open(&t->c->ba, b->in->fd, a->out->fd, doneba, t); |
379 | return; |
380 | } |
381 | |
382 | /*----- That's all, folks -------------------------------------------------*/ |