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