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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: endpt.c,v 1.3 2000/08/01 17:58:25 mdw Exp $ |
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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 $ |
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32 | * Revision 1.3 2000/08/01 17:58:25 mdw |
33 | * Include missing <mLib/alloc.h> header. |
34 | * |
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35 | * Revision 1.2 1999/10/22 22:46:17 mdw |
36 | * When a non-file endpoint is attached to a file, keep the file endpoint |
37 | * open until the nonfile is done. This stops socket sources from |
38 | * resetting their connection limits too early. |
39 | * |
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40 | * Revision 1.1 1999/07/26 23:33:01 mdw |
41 | * Infrastructure for the new design. |
42 | * |
43 | */ |
44 | |
45 | /*----- Header files ------------------------------------------------------*/ |
46 | |
47 | #include "config.h" |
48 | |
49 | #include <errno.h> |
50 | #include <stdio.h> |
51 | #include <stdlib.h> |
52 | #include <string.h> |
53 | |
54 | #include <sys/types.h> |
55 | #include <unistd.h> |
56 | #include <fcntl.h> |
57 | |
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58 | #include <mLib/alloc.h> |
59 | |
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60 | #include "chan.h" |
61 | #include "endpt.h" |
62 | |
63 | /*----- Data structures ---------------------------------------------------*/ |
64 | |
65 | /* --- Pairs of channels --- * |
66 | * |
67 | * Channels are always allocated and freed in pairs. It makes sense to keep |
68 | * the pair together. (It also wastes less memory.) |
69 | */ |
70 | |
71 | typedef struct chanpair { |
72 | struct chanpair *next; |
73 | chan ab, ba; |
74 | } chanpair; |
75 | |
76 | /* --- The `private data structure' --- * |
77 | * |
78 | * This is called a @tango@ because it takes two (endpoints). |
79 | */ |
80 | |
81 | typedef struct tango { |
82 | struct tango *next, *prev; /* A big list of all tangos */ |
83 | endpt *a, *b; /* The two endpoints */ |
84 | unsigned s; /* State of the connection */ |
85 | chanpair *c; /* The pair of channels */ |
86 | } tango; |
87 | |
88 | #define EPS_AB 1u |
89 | #define EPS_BA 2u |
90 | |
91 | /*----- Static variables --------------------------------------------------*/ |
92 | |
93 | static chanpair *chans = 0; /* List of spare channel pairs */ |
94 | static tango *tangos = 0; /* List of tangos */ |
95 | |
96 | /*----- Main code ---------------------------------------------------------*/ |
97 | |
98 | /* --- @doneab@, @doneba@ --- * |
99 | * |
100 | * Arguments: @void *p@ = pointer to a tango block |
101 | * |
102 | * Returns: --- |
103 | * |
104 | * Use: Handles completion of a channel. |
105 | */ |
106 | |
107 | static void doneab(void *p) |
108 | { |
109 | tango *t = p; |
110 | t->s &= ~EPS_AB; |
111 | t->b->ops->wclose(t->b); |
112 | if (!t->s) |
113 | endpt_kill(t->a); |
114 | } |
115 | |
116 | static void doneba(void *p) |
117 | { |
118 | tango *t = p; |
119 | t->s &= ~EPS_BA; |
120 | t->a->ops->wclose(t->a); |
121 | if (!t->s) |
122 | endpt_kill(t->a); |
123 | } |
124 | |
125 | /* --- @endpt_kill@ --- * |
126 | * |
127 | * Arguments: @endpt *a@ = an endpoint |
128 | * |
129 | * Returns: --- |
130 | * |
131 | * Use: Kills an endpoint. If the endpoint is joined to another, the |
132 | * other endpoint is also killed, as is the connection between |
133 | * them (and that's the tricky bit). |
134 | */ |
135 | |
136 | void endpt_kill(endpt *a) |
137 | { |
138 | tango *t; |
139 | endpt *b; |
140 | |
141 | /* --- If the endpont is unconnected, just close it --- */ |
142 | |
143 | if (!a->t) { |
144 | a->ops->close(a); |
145 | return; |
146 | } |
147 | t = a->t; |
148 | a = t->a; |
149 | b = t->b; |
150 | |
151 | /* --- See whether to close channels --- * |
152 | * |
153 | * I'll only have opened channels if both things are files. Also, the |
154 | * channel from @b@ to @a@ will only be open if @b@ is not pending. |
155 | */ |
156 | |
157 | if (a->f & b->f & EPF_FILE) { |
158 | if (t->s & EPS_AB) |
159 | chan_close(&t->c->ab); |
160 | if (!(b->f & EPF_PENDING) && (t->s & EPS_BA)) |
161 | chan_close(&t->c->ba); |
162 | t->c->next = chans; |
163 | chans = t->c; |
164 | } |
165 | |
166 | /* --- Now just throw the endpoints and tango block away --- */ |
167 | |
168 | a->ops->close(a); |
169 | b->ops->close(b); |
170 | if (t->next) |
171 | t->next->prev = t->prev; |
172 | if (t->prev) |
173 | t->prev->next = t->next; |
174 | else |
175 | tangos = t->next; |
176 | DESTROY(t); |
177 | } |
178 | |
179 | /* --- @endpt_killall@ --- * |
180 | * |
181 | * Arguments: --- |
182 | * |
183 | * Returns: --- |
184 | * |
185 | * Use: Destroys all current endpoint connections. Used when |
186 | * shutting down. |
187 | */ |
188 | |
189 | void endpt_killall(void) |
190 | { |
191 | tango *t = tangos; |
192 | while (t) { |
193 | tango *tt = t; |
194 | t = t->next; |
195 | endpt_kill(tt->a); |
196 | } |
197 | tangos = 0; |
198 | } |
199 | |
200 | /* --- @endpt_join@ --- * |
201 | * |
202 | * Arguments: @endpt *a@ = pointer to first endpoint |
203 | * @endpt *b@ = pointer to second endpoint |
204 | * |
205 | * Returns: --- |
206 | * |
207 | * Use: Joins two endpoints together. It's OK to join endpoints |
208 | * which are already joined; in fact, the the right thing to do |
209 | * when your endpoint decides that it's not pending any more is |
210 | * to join it to its partner again. |
211 | */ |
212 | |
213 | void endpt_join(endpt *a, endpt *b) |
214 | { |
215 | tango *t = a->t; |
216 | |
217 | /* --- If there is no tango yet, create one --- */ |
218 | |
219 | if (!t) { |
220 | t = CREATE(tango); |
221 | t->next = tangos; |
222 | t->prev = 0; |
223 | t->a = b->other = a; |
224 | t->b = a->other = b; |
225 | a->t = b->t = t; |
226 | t->s = EPS_AB | EPS_BA; |
227 | t->c = 0; |
228 | if (tangos) |
229 | tangos->prev = t; |
230 | tangos = t; |
231 | } |
232 | |
233 | /* --- If both endpoints are unfinished, leave them for a while --- */ |
234 | |
235 | if (a->f & b->f & EPF_PENDING) |
236 | return; |
237 | |
238 | /* --- At least one endpoint is ready --- * |
239 | * |
240 | * If both endpoints are files then I can speculatively create the |
241 | * channels, which will let data start flowing a bit. Otherwise, I'll just |
242 | * have to wait some more. |
243 | */ |
244 | |
245 | if ((a->f | b->f) & EPF_PENDING) { |
246 | |
247 | /* --- Only be interested if both things are files --- */ |
248 | |
249 | if (!t->c && (a->f & b->f & EPF_FILE)) { |
250 | |
251 | /* --- Allocate a pair of channels --- */ |
252 | |
253 | if (!chans) |
254 | t->c = xmalloc(sizeof(*t->c)); |
255 | else { |
256 | t->c = chans; |
257 | chans = chans->next; |
258 | } |
259 | |
260 | /* --- Make @a@ the endpoint which is ready --- */ |
261 | |
262 | if (a->f & EPF_PENDING) { |
263 | t->b = a; t->a = b; |
264 | a = t->a; b = t->b; |
265 | } |
266 | |
267 | /* --- Open one channel to read from @a@ --- */ |
268 | |
269 | chan_open(&t->c->ab, a->in->fd, -1, doneab, t); |
270 | } |
271 | return; |
272 | } |
273 | |
274 | /* --- Both endpoints are now ready --- * |
275 | * |
276 | * There are four cases to consider here. |
277 | */ |
278 | |
279 | /* --- Case 1 --- * |
280 | * |
281 | * Neither endpoint is a file. I need to make a pair of pipes and tell |
282 | * both endpoints to attach to them. I can then close the pipes and |
283 | * discard the tango. |
284 | */ |
285 | |
286 | if (!((a->f | b->f) & EPF_FILE)) { |
287 | int pab[2], pba[2]; |
288 | reffd *rab, *wab, *rba, *wba; |
289 | |
290 | /* --- Create the pipes --- */ |
291 | |
292 | if (pipe(pab)) goto tidy_nofile_0; |
293 | if (pipe(pba)) goto tidy_nofile_1; |
294 | |
295 | /* --- Attach reference counters --- */ |
296 | |
297 | rab = reffd_init(pab[0]); wab = reffd_init(pab[1]); |
298 | rba = reffd_init(pba[0]); wba = reffd_init(pba[1]); |
299 | a->ops->attach(a, rba, wab); |
300 | b->ops->attach(b, rab, wba); |
301 | REFFD_DEC(rab); REFFD_DEC(wab); |
302 | REFFD_DEC(rba); REFFD_DEC(wba); |
303 | goto tidy_nofile_0; |
304 | |
305 | /* --- Tidy up after a mess --- */ |
306 | |
307 | tidy_nofile_1: |
308 | close(pab[0]); close(pab[1]); |
309 | tidy_nofile_0: |
310 | a->ops->close(a); |
311 | b->ops->close(b); |
312 | if (t->next) |
313 | t->next->prev = t->prev; |
314 | if (t->prev) |
315 | t->prev->next = t->next; |
316 | else |
317 | tangos = t->next; |
318 | DESTROY(t); |
319 | return; |
320 | } |
321 | |
322 | /* --- Case 2 --- * |
323 | * |
324 | * One endpoint is a file, the other isn't. I just attach the other |
325 | * endpoint to the file and stand well back. |
326 | */ |
327 | |
328 | if ((a->f ^ b->f) & EPF_FILE) { |
329 | |
330 | /* --- Let @a@ be the endpoint with the file --- */ |
331 | |
332 | if (b->f & EPF_FILE) { |
333 | endpt *e; |
334 | e = a; a = b; b = e; |
335 | } |
336 | |
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337 | /* --- Attach the non-file endpoint to the file and run away --- * |
338 | * |
339 | * Leave it as the non-file's responsibility to close the other endpoint |
340 | * when it's ready. It should also close itself at that time. |
341 | */ |
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342 | |
343 | b->ops->attach(b, a->in, a->out); |
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344 | b->ops->file(b, a); |
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345 | if (t->next) |
346 | t->next->prev = t->prev; |
347 | if (t->prev) |
348 | t->prev->next = t->next; |
349 | else |
350 | tangos = t->next; |
351 | DESTROY(t); |
352 | return; |
353 | } |
354 | |
355 | /* --- Case 3 --- * |
356 | * |
357 | * Both endpoints are files and I have a partially created channel pair. I |
358 | * need to create the other channel and add a destination to the first one. |
359 | * In this case, @t->b@ is the endpoint which has just finished setting |
360 | * itself up. |
361 | */ |
362 | |
363 | if (t->c) { |
364 | a = t->a; b = t->b; |
365 | chan_open(&t->c->ba, b->in->fd, a->out->fd, doneba, t); |
366 | chan_dest(&t->c->ab, b->out->fd); |
367 | return; |
368 | } |
369 | |
370 | /* --- Case 4 --- * |
371 | * |
372 | * Both endpoints are files and I don't have a partially created channel |
373 | * pair. I need to allocate a channel pair and create both channels. |
374 | */ |
375 | |
376 | if (!chans) |
377 | t->c = xmalloc(sizeof(*t->c)); |
378 | else { |
379 | t->c = chans; |
380 | chans = chans->next; |
381 | } |
382 | chan_open(&t->c->ab, a->in->fd, b->out->fd, doneab, t); |
383 | chan_open(&t->c->ba, b->in->fd, a->out->fd, doneba, t); |
384 | return; |
385 | } |
386 | |
387 | /*----- That's all, folks -------------------------------------------------*/ |