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07d71f34 | 1 | /* -*-c-*- |
07d71f34 | 2 | * |
3 | * Generic endpoint abstraction | |
4 | * | |
5 | * (c) 1999 Straylight/Edgeware | |
6 | */ | |
7 | ||
206212ca | 8 | /*----- Licensing notice --------------------------------------------------* |
07d71f34 | 9 | * |
9155ea97 | 10 | * This file is part of the `fwd' port forwarder. |
07d71f34 | 11 | * |
9155ea97 | 12 | * `fwd' is free software; you can redistribute it and/or modify |
07d71f34 | 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. | |
206212ca | 16 | * |
9155ea97 | 17 | * `fwd' is distributed in the hope that it will be useful, |
07d71f34 | 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. | |
206212ca | 21 | * |
07d71f34 | 22 | * You should have received a copy of the GNU General Public License |
9155ea97 | 23 | * along with `fwd'; if not, write to the Free Software Foundation, |
07d71f34 | 24 | * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
25 | */ | |
26 | ||
9155ea97 | 27 | #include "fwd.h" |
07d71f34 | 28 | |
29 | /*----- Data structures ---------------------------------------------------*/ | |
30 | ||
31 | /* --- Pairs of channels --- * | |
32 | * | |
33 | * Channels are always allocated and freed in pairs. It makes sense to keep | |
34 | * the pair together. (It also wastes less memory.) | |
35 | */ | |
36 | ||
37 | typedef struct chanpair { | |
38 | struct chanpair *next; | |
39 | chan ab, ba; | |
40 | } chanpair; | |
41 | ||
42 | /* --- The `private data structure' --- * | |
43 | * | |
44 | * This is called a @tango@ because it takes two (endpoints). | |
45 | */ | |
46 | ||
47 | typedef struct tango { | |
48 | struct tango *next, *prev; /* A big list of all tangos */ | |
49 | endpt *a, *b; /* The two endpoints */ | |
86c9bc4b | 50 | char *desc; /* Description of the connection */ |
07d71f34 | 51 | unsigned s; /* State of the connection */ |
52 | chanpair *c; /* The pair of channels */ | |
53 | } tango; | |
54 | ||
55 | #define EPS_AB 1u | |
56 | #define EPS_BA 2u | |
57 | ||
58 | /*----- Static variables --------------------------------------------------*/ | |
59 | ||
60 | static chanpair *chans = 0; /* List of spare channel pairs */ | |
61 | static tango *tangos = 0; /* List of tangos */ | |
62 | ||
63 | /*----- Main code ---------------------------------------------------------*/ | |
64 | ||
65 | /* --- @doneab@, @doneba@ --- * | |
66 | * | |
67 | * Arguments: @void *p@ = pointer to a tango block | |
68 | * | |
69 | * Returns: --- | |
70 | * | |
71 | * Use: Handles completion of a channel. | |
72 | */ | |
73 | ||
74 | static void doneab(void *p) | |
75 | { | |
76 | tango *t = p; | |
77 | t->s &= ~EPS_AB; | |
78 | t->b->ops->wclose(t->b); | |
79 | if (!t->s) | |
80 | endpt_kill(t->a); | |
81 | } | |
82 | ||
83 | static void doneba(void *p) | |
84 | { | |
85 | tango *t = p; | |
86 | t->s &= ~EPS_BA; | |
87 | t->a->ops->wclose(t->a); | |
88 | if (!t->s) | |
89 | endpt_kill(t->a); | |
90 | } | |
91 | ||
92 | /* --- @endpt_kill@ --- * | |
93 | * | |
94 | * Arguments: @endpt *a@ = an endpoint | |
95 | * | |
96 | * Returns: --- | |
97 | * | |
98 | * Use: Kills an endpoint. If the endpoint is joined to another, the | |
99 | * other endpoint is also killed, as is the connection between | |
100 | * them (and that's the tricky bit). | |
101 | */ | |
102 | ||
103 | void endpt_kill(endpt *a) | |
104 | { | |
105 | tango *t; | |
106 | endpt *b; | |
107 | ||
108 | /* --- If the endpont is unconnected, just close it --- */ | |
109 | ||
110 | if (!a->t) { | |
111 | a->ops->close(a); | |
112 | return; | |
113 | } | |
114 | t = a->t; | |
115 | a = t->a; | |
116 | b = t->b; | |
117 | ||
118 | /* --- See whether to close channels --- * | |
119 | * | |
120 | * I'll only have opened channels if both things are files. Also, the | |
121 | * channel from @b@ to @a@ will only be open if @b@ is not pending. | |
122 | */ | |
123 | ||
124 | if (a->f & b->f & EPF_FILE) { | |
86c9bc4b | 125 | if (t->c->ab.err) |
d935f68b | 126 | fw_log(NOW, "[%s] error: %s", t->desc, strerror(t->c->ab.err)); |
86c9bc4b | 127 | else if (t->c->ba.err) |
d935f68b | 128 | fw_log(NOW, "[%s] error: %s", t->desc, strerror(t->c->ba.err)); |
07d71f34 | 129 | if (t->s & EPS_AB) |
130 | chan_close(&t->c->ab); | |
131 | if (!(b->f & EPF_PENDING) && (t->s & EPS_BA)) | |
132 | chan_close(&t->c->ba); | |
133 | t->c->next = chans; | |
134 | chans = t->c; | |
135 | } | |
136 | ||
137 | /* --- Now just throw the endpoints and tango block away --- */ | |
138 | ||
139 | a->ops->close(a); | |
140 | b->ops->close(b); | |
141 | if (t->next) | |
142 | t->next->prev = t->prev; | |
143 | if (t->prev) | |
144 | t->prev->next = t->next; | |
145 | else | |
146 | tangos = t->next; | |
86c9bc4b MW |
147 | if (t->desc) |
148 | xfree(t->desc); | |
07d71f34 | 149 | DESTROY(t); |
150 | } | |
151 | ||
152 | /* --- @endpt_killall@ --- * | |
153 | * | |
154 | * Arguments: --- | |
155 | * | |
156 | * Returns: --- | |
157 | * | |
158 | * Use: Destroys all current endpoint connections. Used when | |
159 | * shutting down. | |
160 | */ | |
161 | ||
162 | void endpt_killall(void) | |
163 | { | |
164 | tango *t = tangos; | |
165 | while (t) { | |
166 | tango *tt = t; | |
167 | t = t->next; | |
168 | endpt_kill(tt->a); | |
169 | } | |
170 | tangos = 0; | |
171 | } | |
172 | ||
173 | /* --- @endpt_join@ --- * | |
174 | * | |
175 | * Arguments: @endpt *a@ = pointer to first endpoint | |
176 | * @endpt *b@ = pointer to second endpoint | |
86c9bc4b | 177 | * @const char *desc@ = description of connection |
07d71f34 | 178 | * |
179 | * Returns: --- | |
180 | * | |
181 | * Use: Joins two endpoints together. It's OK to join endpoints | |
182 | * which are already joined; in fact, the the right thing to do | |
183 | * when your endpoint decides that it's not pending any more is | |
184 | * to join it to its partner again. | |
86c9bc4b MW |
185 | * |
186 | * If the endpoints are already connected then the description | |
187 | * string is ignored. The endpoint manager takes a copy of the | |
188 | * string, so you don't need to keep it around. | |
07d71f34 | 189 | */ |
190 | ||
86c9bc4b | 191 | void endpt_join(endpt *a, endpt *b, const char *desc) |
07d71f34 | 192 | { |
193 | tango *t = a->t; | |
194 | ||
195 | /* --- If there is no tango yet, create one --- */ | |
196 | ||
197 | if (!t) { | |
198 | t = CREATE(tango); | |
199 | t->next = tangos; | |
200 | t->prev = 0; | |
201 | t->a = b->other = a; | |
202 | t->b = a->other = b; | |
203 | a->t = b->t = t; | |
204 | t->s = EPS_AB | EPS_BA; | |
205 | t->c = 0; | |
86c9bc4b | 206 | t->desc = xstrdup(desc); |
07d71f34 | 207 | if (tangos) |
208 | tangos->prev = t; | |
209 | tangos = t; | |
210 | } | |
211 | ||
212 | /* --- If both endpoints are unfinished, leave them for a while --- */ | |
213 | ||
214 | if (a->f & b->f & EPF_PENDING) | |
215 | return; | |
216 | ||
217 | /* --- At least one endpoint is ready --- * | |
218 | * | |
219 | * If both endpoints are files then I can speculatively create the | |
220 | * channels, which will let data start flowing a bit. Otherwise, I'll just | |
221 | * have to wait some more. | |
222 | */ | |
223 | ||
224 | if ((a->f | b->f) & EPF_PENDING) { | |
225 | ||
226 | /* --- Only be interested if both things are files --- */ | |
227 | ||
228 | if (!t->c && (a->f & b->f & EPF_FILE)) { | |
229 | ||
230 | /* --- Allocate a pair of channels --- */ | |
231 | ||
232 | if (!chans) | |
233 | t->c = xmalloc(sizeof(*t->c)); | |
234 | else { | |
235 | t->c = chans; | |
236 | chans = chans->next; | |
237 | } | |
238 | ||
239 | /* --- Make @a@ the endpoint which is ready --- */ | |
240 | ||
241 | if (a->f & EPF_PENDING) { | |
242 | t->b = a; t->a = b; | |
243 | a = t->a; b = t->b; | |
244 | } | |
245 | ||
246 | /* --- Open one channel to read from @a@ --- */ | |
247 | ||
248 | chan_open(&t->c->ab, a->in->fd, -1, doneab, t); | |
249 | } | |
250 | return; | |
251 | } | |
252 | ||
253 | /* --- Both endpoints are now ready --- * | |
254 | * | |
255 | * There are four cases to consider here. | |
256 | */ | |
257 | ||
258 | /* --- Case 1 --- * | |
259 | * | |
260 | * Neither endpoint is a file. I need to make a pair of pipes and tell | |
261 | * both endpoints to attach to them. I can then close the pipes and | |
262 | * discard the tango. | |
263 | */ | |
264 | ||
265 | if (!((a->f | b->f) & EPF_FILE)) { | |
266 | int pab[2], pba[2]; | |
267 | reffd *rab, *wab, *rba, *wba; | |
268 | ||
269 | /* --- Create the pipes --- */ | |
270 | ||
271 | if (pipe(pab)) goto tidy_nofile_0; | |
272 | if (pipe(pba)) goto tidy_nofile_1; | |
273 | ||
274 | /* --- Attach reference counters --- */ | |
275 | ||
276 | rab = reffd_init(pab[0]); wab = reffd_init(pab[1]); | |
277 | rba = reffd_init(pba[0]); wba = reffd_init(pba[1]); | |
278 | a->ops->attach(a, rba, wab); | |
279 | b->ops->attach(b, rab, wba); | |
280 | REFFD_DEC(rab); REFFD_DEC(wab); | |
281 | REFFD_DEC(rba); REFFD_DEC(wba); | |
282 | goto tidy_nofile_0; | |
283 | ||
284 | /* --- Tidy up after a mess --- */ | |
285 | ||
286 | tidy_nofile_1: | |
287 | close(pab[0]); close(pab[1]); | |
288 | tidy_nofile_0: | |
289 | a->ops->close(a); | |
290 | b->ops->close(b); | |
291 | if (t->next) | |
292 | t->next->prev = t->prev; | |
293 | if (t->prev) | |
294 | t->prev->next = t->next; | |
295 | else | |
296 | tangos = t->next; | |
297 | DESTROY(t); | |
298 | return; | |
299 | } | |
300 | ||
301 | /* --- Case 2 --- * | |
302 | * | |
303 | * One endpoint is a file, the other isn't. I just attach the other | |
304 | * endpoint to the file and stand well back. | |
305 | */ | |
306 | ||
307 | if ((a->f ^ b->f) & EPF_FILE) { | |
308 | ||
309 | /* --- Let @a@ be the endpoint with the file --- */ | |
310 | ||
311 | if (b->f & EPF_FILE) { | |
312 | endpt *e; | |
313 | e = a; a = b; b = e; | |
314 | } | |
315 | ||
28d2517c | 316 | /* --- Attach the non-file endpoint to the file and run away --- * |
317 | * | |
318 | * Leave it as the non-file's responsibility to close the other endpoint | |
319 | * when it's ready. It should also close itself at that time. | |
320 | */ | |
07d71f34 | 321 | |
322 | b->ops->attach(b, a->in, a->out); | |
28d2517c | 323 | b->ops->file(b, a); |
07d71f34 | 324 | if (t->next) |
325 | t->next->prev = t->prev; | |
326 | if (t->prev) | |
327 | t->prev->next = t->next; | |
328 | else | |
329 | tangos = t->next; | |
330 | DESTROY(t); | |
331 | return; | |
332 | } | |
333 | ||
334 | /* --- Case 3 --- * | |
335 | * | |
336 | * Both endpoints are files and I have a partially created channel pair. I | |
337 | * need to create the other channel and add a destination to the first one. | |
338 | * In this case, @t->b@ is the endpoint which has just finished setting | |
339 | * itself up. | |
340 | */ | |
341 | ||
342 | if (t->c) { | |
343 | a = t->a; b = t->b; | |
344 | chan_open(&t->c->ba, b->in->fd, a->out->fd, doneba, t); | |
345 | chan_dest(&t->c->ab, b->out->fd); | |
346 | return; | |
347 | } | |
348 | ||
349 | /* --- Case 4 --- * | |
350 | * | |
351 | * Both endpoints are files and I don't have a partially created channel | |
352 | * pair. I need to allocate a channel pair and create both channels. | |
353 | */ | |
354 | ||
355 | if (!chans) | |
356 | t->c = xmalloc(sizeof(*t->c)); | |
357 | else { | |
358 | t->c = chans; | |
359 | chans = chans->next; | |
360 | } | |
361 | chan_open(&t->c->ab, a->in->fd, b->out->fd, doneab, t); | |
362 | chan_open(&t->c->ba, b->in->fd, a->out->fd, doneba, t); | |
363 | return; | |
206212ca | 364 | } |
07d71f34 | 365 | |
366 | /*----- That's all, folks -------------------------------------------------*/ |