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1 | /* -*-c-*- |
2 | * |
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3 | * Generic endpoint abstraction |
4 | * |
5 | * (c) 1999 Straylight/Edgeware |
6 | */ |
7 | |
8 | /*----- Licensing notice --------------------------------------------------* |
9 | * |
10 | * This file is part of the `fw' port forwarder. |
11 | * |
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. |
16 | * |
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. |
21 | * |
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. |
25 | */ |
26 | |
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27 | /*----- Header files ------------------------------------------------------*/ |
28 | |
29 | #include "config.h" |
30 | |
31 | #include <errno.h> |
32 | #include <stdio.h> |
33 | #include <stdlib.h> |
34 | #include <string.h> |
35 | |
36 | #include <sys/types.h> |
37 | #include <unistd.h> |
38 | #include <fcntl.h> |
39 | |
69ba0d40 |
40 | #include <mLib/alloc.h> |
41 | |
07d71f34 |
42 | #include "chan.h" |
43 | #include "endpt.h" |
44 | |
45 | /*----- Data structures ---------------------------------------------------*/ |
46 | |
47 | /* --- Pairs of channels --- * |
48 | * |
49 | * Channels are always allocated and freed in pairs. It makes sense to keep |
50 | * the pair together. (It also wastes less memory.) |
51 | */ |
52 | |
53 | typedef struct chanpair { |
54 | struct chanpair *next; |
55 | chan ab, ba; |
56 | } chanpair; |
57 | |
58 | /* --- The `private data structure' --- * |
59 | * |
60 | * This is called a @tango@ because it takes two (endpoints). |
61 | */ |
62 | |
63 | typedef struct tango { |
64 | struct tango *next, *prev; /* A big list of all tangos */ |
65 | endpt *a, *b; /* The two endpoints */ |
66 | unsigned s; /* State of the connection */ |
67 | chanpair *c; /* The pair of channels */ |
68 | } tango; |
69 | |
70 | #define EPS_AB 1u |
71 | #define EPS_BA 2u |
72 | |
73 | /*----- Static variables --------------------------------------------------*/ |
74 | |
75 | static chanpair *chans = 0; /* List of spare channel pairs */ |
76 | static tango *tangos = 0; /* List of tangos */ |
77 | |
78 | /*----- Main code ---------------------------------------------------------*/ |
79 | |
80 | /* --- @doneab@, @doneba@ --- * |
81 | * |
82 | * Arguments: @void *p@ = pointer to a tango block |
83 | * |
84 | * Returns: --- |
85 | * |
86 | * Use: Handles completion of a channel. |
87 | */ |
88 | |
89 | static void doneab(void *p) |
90 | { |
91 | tango *t = p; |
92 | t->s &= ~EPS_AB; |
93 | t->b->ops->wclose(t->b); |
94 | if (!t->s) |
95 | endpt_kill(t->a); |
96 | } |
97 | |
98 | static void doneba(void *p) |
99 | { |
100 | tango *t = p; |
101 | t->s &= ~EPS_BA; |
102 | t->a->ops->wclose(t->a); |
103 | if (!t->s) |
104 | endpt_kill(t->a); |
105 | } |
106 | |
107 | /* --- @endpt_kill@ --- * |
108 | * |
109 | * Arguments: @endpt *a@ = an endpoint |
110 | * |
111 | * Returns: --- |
112 | * |
113 | * Use: Kills an endpoint. If the endpoint is joined to another, the |
114 | * other endpoint is also killed, as is the connection between |
115 | * them (and that's the tricky bit). |
116 | */ |
117 | |
118 | void endpt_kill(endpt *a) |
119 | { |
120 | tango *t; |
121 | endpt *b; |
122 | |
123 | /* --- If the endpont is unconnected, just close it --- */ |
124 | |
125 | if (!a->t) { |
126 | a->ops->close(a); |
127 | return; |
128 | } |
129 | t = a->t; |
130 | a = t->a; |
131 | b = t->b; |
132 | |
133 | /* --- See whether to close channels --- * |
134 | * |
135 | * I'll only have opened channels if both things are files. Also, the |
136 | * channel from @b@ to @a@ will only be open if @b@ is not pending. |
137 | */ |
138 | |
139 | if (a->f & b->f & EPF_FILE) { |
140 | if (t->s & EPS_AB) |
141 | chan_close(&t->c->ab); |
142 | if (!(b->f & EPF_PENDING) && (t->s & EPS_BA)) |
143 | chan_close(&t->c->ba); |
144 | t->c->next = chans; |
145 | chans = t->c; |
146 | } |
147 | |
148 | /* --- Now just throw the endpoints and tango block away --- */ |
149 | |
150 | a->ops->close(a); |
151 | b->ops->close(b); |
152 | if (t->next) |
153 | t->next->prev = t->prev; |
154 | if (t->prev) |
155 | t->prev->next = t->next; |
156 | else |
157 | tangos = t->next; |
158 | DESTROY(t); |
159 | } |
160 | |
161 | /* --- @endpt_killall@ --- * |
162 | * |
163 | * Arguments: --- |
164 | * |
165 | * Returns: --- |
166 | * |
167 | * Use: Destroys all current endpoint connections. Used when |
168 | * shutting down. |
169 | */ |
170 | |
171 | void endpt_killall(void) |
172 | { |
173 | tango *t = tangos; |
174 | while (t) { |
175 | tango *tt = t; |
176 | t = t->next; |
177 | endpt_kill(tt->a); |
178 | } |
179 | tangos = 0; |
180 | } |
181 | |
182 | /* --- @endpt_join@ --- * |
183 | * |
184 | * Arguments: @endpt *a@ = pointer to first endpoint |
185 | * @endpt *b@ = pointer to second endpoint |
186 | * |
187 | * Returns: --- |
188 | * |
189 | * Use: Joins two endpoints together. It's OK to join endpoints |
190 | * which are already joined; in fact, the the right thing to do |
191 | * when your endpoint decides that it's not pending any more is |
192 | * to join it to its partner again. |
193 | */ |
194 | |
195 | void endpt_join(endpt *a, endpt *b) |
196 | { |
197 | tango *t = a->t; |
198 | |
199 | /* --- If there is no tango yet, create one --- */ |
200 | |
201 | if (!t) { |
202 | t = CREATE(tango); |
203 | t->next = tangos; |
204 | t->prev = 0; |
205 | t->a = b->other = a; |
206 | t->b = a->other = b; |
207 | a->t = b->t = t; |
208 | t->s = EPS_AB | EPS_BA; |
209 | t->c = 0; |
210 | if (tangos) |
211 | tangos->prev = t; |
212 | tangos = t; |
213 | } |
214 | |
215 | /* --- If both endpoints are unfinished, leave them for a while --- */ |
216 | |
217 | if (a->f & b->f & EPF_PENDING) |
218 | return; |
219 | |
220 | /* --- At least one endpoint is ready --- * |
221 | * |
222 | * If both endpoints are files then I can speculatively create the |
223 | * channels, which will let data start flowing a bit. Otherwise, I'll just |
224 | * have to wait some more. |
225 | */ |
226 | |
227 | if ((a->f | b->f) & EPF_PENDING) { |
228 | |
229 | /* --- Only be interested if both things are files --- */ |
230 | |
231 | if (!t->c && (a->f & b->f & EPF_FILE)) { |
232 | |
233 | /* --- Allocate a pair of channels --- */ |
234 | |
235 | if (!chans) |
236 | t->c = xmalloc(sizeof(*t->c)); |
237 | else { |
238 | t->c = chans; |
239 | chans = chans->next; |
240 | } |
241 | |
242 | /* --- Make @a@ the endpoint which is ready --- */ |
243 | |
244 | if (a->f & EPF_PENDING) { |
245 | t->b = a; t->a = b; |
246 | a = t->a; b = t->b; |
247 | } |
248 | |
249 | /* --- Open one channel to read from @a@ --- */ |
250 | |
251 | chan_open(&t->c->ab, a->in->fd, -1, doneab, t); |
252 | } |
253 | return; |
254 | } |
255 | |
256 | /* --- Both endpoints are now ready --- * |
257 | * |
258 | * There are four cases to consider here. |
259 | */ |
260 | |
261 | /* --- Case 1 --- * |
262 | * |
263 | * Neither endpoint is a file. I need to make a pair of pipes and tell |
264 | * both endpoints to attach to them. I can then close the pipes and |
265 | * discard the tango. |
266 | */ |
267 | |
268 | if (!((a->f | b->f) & EPF_FILE)) { |
269 | int pab[2], pba[2]; |
270 | reffd *rab, *wab, *rba, *wba; |
271 | |
272 | /* --- Create the pipes --- */ |
273 | |
274 | if (pipe(pab)) goto tidy_nofile_0; |
275 | if (pipe(pba)) goto tidy_nofile_1; |
276 | |
277 | /* --- Attach reference counters --- */ |
278 | |
279 | rab = reffd_init(pab[0]); wab = reffd_init(pab[1]); |
280 | rba = reffd_init(pba[0]); wba = reffd_init(pba[1]); |
281 | a->ops->attach(a, rba, wab); |
282 | b->ops->attach(b, rab, wba); |
283 | REFFD_DEC(rab); REFFD_DEC(wab); |
284 | REFFD_DEC(rba); REFFD_DEC(wba); |
285 | goto tidy_nofile_0; |
286 | |
287 | /* --- Tidy up after a mess --- */ |
288 | |
289 | tidy_nofile_1: |
290 | close(pab[0]); close(pab[1]); |
291 | tidy_nofile_0: |
292 | a->ops->close(a); |
293 | b->ops->close(b); |
294 | if (t->next) |
295 | t->next->prev = t->prev; |
296 | if (t->prev) |
297 | t->prev->next = t->next; |
298 | else |
299 | tangos = t->next; |
300 | DESTROY(t); |
301 | return; |
302 | } |
303 | |
304 | /* --- Case 2 --- * |
305 | * |
306 | * One endpoint is a file, the other isn't. I just attach the other |
307 | * endpoint to the file and stand well back. |
308 | */ |
309 | |
310 | if ((a->f ^ b->f) & EPF_FILE) { |
311 | |
312 | /* --- Let @a@ be the endpoint with the file --- */ |
313 | |
314 | if (b->f & EPF_FILE) { |
315 | endpt *e; |
316 | e = a; a = b; b = e; |
317 | } |
318 | |
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319 | /* --- Attach the non-file endpoint to the file and run away --- * |
320 | * |
321 | * Leave it as the non-file's responsibility to close the other endpoint |
322 | * when it's ready. It should also close itself at that time. |
323 | */ |
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324 | |
325 | b->ops->attach(b, a->in, a->out); |
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326 | b->ops->file(b, a); |
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327 | if (t->next) |
328 | t->next->prev = t->prev; |
329 | if (t->prev) |
330 | t->prev->next = t->next; |
331 | else |
332 | tangos = t->next; |
333 | DESTROY(t); |
334 | return; |
335 | } |
336 | |
337 | /* --- Case 3 --- * |
338 | * |
339 | * Both endpoints are files and I have a partially created channel pair. I |
340 | * need to create the other channel and add a destination to the first one. |
341 | * In this case, @t->b@ is the endpoint which has just finished setting |
342 | * itself up. |
343 | */ |
344 | |
345 | if (t->c) { |
346 | a = t->a; b = t->b; |
347 | chan_open(&t->c->ba, b->in->fd, a->out->fd, doneba, t); |
348 | chan_dest(&t->c->ab, b->out->fd); |
349 | return; |
350 | } |
351 | |
352 | /* --- Case 4 --- * |
353 | * |
354 | * Both endpoints are files and I don't have a partially created channel |
355 | * pair. I need to allocate a channel pair and create both channels. |
356 | */ |
357 | |
358 | if (!chans) |
359 | t->c = xmalloc(sizeof(*t->c)); |
360 | else { |
361 | t->c = chans; |
362 | chans = chans->next; |
363 | } |
364 | chan_open(&t->c->ab, a->in->fd, b->out->fd, doneab, t); |
365 | chan_open(&t->c->ba, b->in->fd, a->out->fd, doneba, t); |
366 | return; |
367 | } |
368 | |
369 | /*----- That's all, folks -------------------------------------------------*/ |