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-rw-r--r--src/util/helper.c716
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diff --git a/src/util/helper.c b/src/util/helper.c
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1/*
2 This file is part of GNUnet.
3 Copyright (C) 2011, 2012 Christian Grothoff
4
5 GNUnet is free software: you can redistribute it and/or modify it
6 under the terms of the GNU Affero General Public License as published
7 by the Free Software Foundation, either version 3 of the License,
8 or (at your option) any later version.
9
10 GNUnet is distributed in the hope that it will be useful, but
11 WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Affero General Public License for more details.
14
15 You should have received a copy of the GNU Affero General Public License
16 along with this program. If not, see <http://www.gnu.org/licenses/>.
17
18 SPDX-License-Identifier: AGPL3.0-or-later
19 */
20
21/**
22 * @file util/helper.c
23 * @brief API for dealing with (SUID) helper processes that communicate via
24 * GNUNET_MessageHeaders on stdin/stdout
25 * @author Philipp Toelke
26 * @author Christian Grothoff
27 */
28#include "platform.h"
29#include "gnunet_util_lib.h"
30#include "gnunet_mst_lib.h"
31
32
33/**
34 * Entry in the queue of messages we need to transmit to the helper.
35 */
36struct GNUNET_HELPER_SendHandle
37{
38 /**
39 * This is an entry in a DLL.
40 */
41 struct GNUNET_HELPER_SendHandle *next;
42
43 /**
44 * This is an entry in a DLL.
45 */
46 struct GNUNET_HELPER_SendHandle *prev;
47
48 /**
49 * Message to transmit (allocated at the end of this struct)
50 */
51 const struct GNUNET_MessageHeader *msg;
52
53 /**
54 * The handle to a helper process.
55 */
56 struct GNUNET_HELPER_Handle *h;
57
58 /**
59 * Function to call upon completion.
60 */
61 GNUNET_HELPER_Continuation cont;
62
63 /**
64 * Closure to 'cont'.
65 */
66 void *cont_cls;
67
68 /**
69 * Current write position.
70 */
71 unsigned int wpos;
72};
73
74
75/**
76 * The handle to a helper process.
77 */
78struct GNUNET_HELPER_Handle
79{
80 /**
81 * PipeHandle to receive data from the helper
82 */
83 struct GNUNET_DISK_PipeHandle *helper_in;
84
85 /**
86 * PipeHandle to send data to the helper
87 */
88 struct GNUNET_DISK_PipeHandle *helper_out;
89
90 /**
91 * FileHandle to receive data from the helper
92 */
93 const struct GNUNET_DISK_FileHandle *fh_from_helper;
94
95 /**
96 * FileHandle to send data to the helper
97 */
98 const struct GNUNET_DISK_FileHandle *fh_to_helper;
99
100 /**
101 * The process id of the helper
102 */
103 struct GNUNET_OS_Process *helper_proc;
104
105 /**
106 * The Message-Tokenizer that tokenizes the messages coming from the helper
107 */
108 struct GNUNET_MessageStreamTokenizer *mst;
109
110 /**
111 * The exception callback
112 */
113 GNUNET_HELPER_ExceptionCallback exp_cb;
114
115 /**
116 * The closure for callbacks
117 */
118 void *cb_cls;
119
120 /**
121 * First message queued for transmission to helper.
122 */
123 struct GNUNET_HELPER_SendHandle *sh_head;
124
125 /**
126 * Last message queued for transmission to helper.
127 */
128 struct GNUNET_HELPER_SendHandle *sh_tail;
129
130 /**
131 * Binary to run.
132 */
133 char *binary_name;
134
135 /**
136 * NULL-terminated list of command-line arguments.
137 */
138 char **binary_argv;
139
140 /**
141 * Task to read from the helper.
142 */
143 struct GNUNET_SCHEDULER_Task *read_task;
144
145 /**
146 * Task to read from the helper.
147 */
148 struct GNUNET_SCHEDULER_Task *write_task;
149
150 /**
151 * Restart task.
152 */
153 struct GNUNET_SCHEDULER_Task *restart_task;
154
155 /**
156 * Does the helper support the use of a control pipe for signalling?
157 */
158 int with_control_pipe;
159
160 /**
161 * Count start attempts to increase linear back off
162 */
163 unsigned int retry_back_off;
164};
165
166
167/**
168 * Sends termination signal to the helper process. The helper process is not
169 * reaped; call GNUNET_HELPER_wait() for reaping the dead helper process.
170 *
171 * @param h the helper handle
172 * @param soft_kill if GNUNET_YES, signals termination by closing the helper's
173 * stdin; GNUNET_NO to signal termination by sending SIGTERM to helper
174 * @return #GNUNET_OK on success; #GNUNET_SYSERR on error
175 */
176int
177GNUNET_HELPER_kill (struct GNUNET_HELPER_Handle *h, int soft_kill)
178{
179 struct GNUNET_HELPER_SendHandle *sh;
180 int ret;
181
182 while (NULL != (sh = h->sh_head))
183 {
184 GNUNET_CONTAINER_DLL_remove (h->sh_head, h->sh_tail, sh);
185 if (NULL != sh->cont)
186 sh->cont (sh->cont_cls, GNUNET_NO);
187 GNUNET_free (sh);
188 }
189 if (NULL != h->restart_task)
190 {
191 GNUNET_SCHEDULER_cancel (h->restart_task);
192 h->restart_task = NULL;
193 }
194 if (NULL != h->read_task)
195 {
196 GNUNET_SCHEDULER_cancel (h->read_task);
197 h->read_task = NULL;
198 }
199 if (NULL == h->helper_proc)
200 return GNUNET_SYSERR;
201 if (GNUNET_YES == soft_kill)
202 {
203 /* soft-kill only possible with pipes */
204 GNUNET_assert (NULL != h->helper_in);
205 ret = GNUNET_DISK_pipe_close (h->helper_in);
206 h->helper_in = NULL;
207 h->fh_to_helper = NULL;
208 return ret;
209 }
210 if (0 != GNUNET_OS_process_kill (h->helper_proc, GNUNET_TERM_SIG))
211 return GNUNET_SYSERR;
212 return GNUNET_OK;
213}
214
215
216/**
217 * Reap the helper process. This call is blocking(!). The helper process
218 * should either be sent a termination signal before or should be dead before
219 * calling this function
220 *
221 * @param h the helper handle
222 * @return #GNUNET_OK on success; #GNUNET_SYSERR on error
223 */
224int
225GNUNET_HELPER_wait (struct GNUNET_HELPER_Handle *h)
226{
227 struct GNUNET_HELPER_SendHandle *sh;
228 int ret;
229
230 ret = GNUNET_SYSERR;
231 if (NULL != h->helper_proc)
232 {
233 ret = GNUNET_OS_process_wait (h->helper_proc);
234 GNUNET_OS_process_destroy (h->helper_proc);
235 h->helper_proc = NULL;
236 }
237 if (NULL != h->read_task)
238 {
239 GNUNET_SCHEDULER_cancel (h->read_task);
240 h->read_task = NULL;
241 }
242 if (NULL != h->write_task)
243 {
244 GNUNET_SCHEDULER_cancel (h->write_task);
245 h->write_task = NULL;
246 }
247 if (NULL != h->helper_in)
248 {
249 GNUNET_DISK_pipe_close (h->helper_in);
250 h->helper_in = NULL;
251 h->fh_to_helper = NULL;
252 }
253 if (NULL != h->helper_out)
254 {
255 GNUNET_DISK_pipe_close (h->helper_out);
256 h->helper_out = NULL;
257 h->fh_from_helper = NULL;
258 }
259 while (NULL != (sh = h->sh_head))
260 {
261 GNUNET_CONTAINER_DLL_remove (h->sh_head, h->sh_tail, sh);
262 if (NULL != sh->cont)
263 sh->cont (sh->cont_cls, GNUNET_NO);
264 GNUNET_free (sh);
265 }
266 /* purge MST buffer */
267 if (NULL != h->mst)
268 (void) GNUNET_MST_from_buffer (h->mst, NULL, 0, GNUNET_YES, GNUNET_NO);
269 return ret;
270}
271
272
273/**
274 * Stop the helper process, we're closing down or had an error.
275 *
276 * @param h handle to the helper process
277 * @param soft_kill if #GNUNET_YES, signals termination by closing the helper's
278 * stdin; #GNUNET_NO to signal termination by sending SIGTERM to helper
279 */
280static void
281stop_helper (struct GNUNET_HELPER_Handle *h, int soft_kill)
282{
283 if (NULL != h->restart_task)
284 {
285 GNUNET_SCHEDULER_cancel (h->restart_task);
286 h->restart_task = NULL;
287 }
288 else
289 {
290 GNUNET_break (GNUNET_OK == GNUNET_HELPER_kill (h, soft_kill));
291 GNUNET_break (GNUNET_OK == GNUNET_HELPER_wait (h));
292 }
293}
294
295
296/**
297 * Restart the helper process.
298 *
299 * @param cls handle to the helper process
300 */
301static void
302restart_task (void *cls);
303
304
305/**
306 * Read from the helper-process
307 *
308 * @param cls handle to the helper process
309 */
310static void
311helper_read (void *cls)
312{
313 struct GNUNET_HELPER_Handle *h = cls;
314 char buf[GNUNET_MAX_MESSAGE_SIZE] GNUNET_ALIGN;
315 ssize_t t;
316
317 h->read_task = NULL;
318 t = GNUNET_DISK_file_read (h->fh_from_helper, &buf, sizeof(buf));
319 if (t < 0)
320 {
321 /* On read-error, restart the helper */
322 GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
323 _ ("Error reading from `%s': %s\n"),
324 h->binary_name,
325 strerror (errno));
326 if (NULL != h->exp_cb)
327 {
328 h->exp_cb (h->cb_cls);
329 GNUNET_HELPER_stop (h, GNUNET_NO);
330 return;
331 }
332 stop_helper (h, GNUNET_NO);
333 /* Restart the helper */
334 h->restart_task = GNUNET_SCHEDULER_add_delayed (
335 GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS,
336 h->retry_back_off),
337 &restart_task,
338 h);
339 return;
340 }
341 if (0 == t)
342 {
343 /* this happens if the helper is shut down via a
344 signal, so it is not a "hard" error */
345 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
346 "Got 0 bytes from helper `%s' (EOF)\n",
347 h->binary_name);
348 if (NULL != h->exp_cb)
349 {
350 h->exp_cb (h->cb_cls);
351 GNUNET_HELPER_stop (h, GNUNET_NO);
352 return;
353 }
354 stop_helper (h, GNUNET_NO);
355 /* Restart the helper */
356 h->restart_task = GNUNET_SCHEDULER_add_delayed (
357 GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS,
358 h->retry_back_off),
359 &restart_task,
360 h);
361 return;
362 }
363 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
364 "Got %u bytes from helper `%s'\n",
365 (unsigned int) t,
366 h->binary_name);
367 h->read_task = GNUNET_SCHEDULER_add_read_file (GNUNET_TIME_UNIT_FOREVER_REL,
368 h->fh_from_helper,
369 &helper_read,
370 h);
371 if (GNUNET_SYSERR ==
372 GNUNET_MST_from_buffer (h->mst, buf, t, GNUNET_NO, GNUNET_NO))
373 {
374 GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
375 _ ("Failed to parse inbound message from helper `%s'\n"),
376 h->binary_name);
377 if (NULL != h->exp_cb)
378 {
379 h->exp_cb (h->cb_cls);
380 GNUNET_HELPER_stop (h, GNUNET_NO);
381 return;
382 }
383 stop_helper (h, GNUNET_NO);
384 /* Restart the helper */
385 h->restart_task = GNUNET_SCHEDULER_add_delayed (
386 GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS,
387 h->retry_back_off),
388 &restart_task,
389 h);
390 return;
391 }
392}
393
394
395/**
396 * Start the helper process.
397 *
398 * @param h handle to the helper process
399 */
400static void
401start_helper (struct GNUNET_HELPER_Handle *h)
402{
403 h->helper_in =
404 GNUNET_DISK_pipe (GNUNET_DISK_PF_BLOCKING_RW);
405 h->helper_out =
406 GNUNET_DISK_pipe (GNUNET_DISK_PF_BLOCKING_RW);
407 if ((h->helper_in == NULL) || (h->helper_out == NULL))
408 {
409 /* out of file descriptors? try again later... */
410 stop_helper (h, GNUNET_NO);
411 h->restart_task = GNUNET_SCHEDULER_add_delayed (
412 GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS,
413 h->retry_back_off),
414 &restart_task,
415 h);
416 return;
417 }
418 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
419 "Starting HELPER process `%s'\n",
420 h->binary_name);
421 h->fh_from_helper =
422 GNUNET_DISK_pipe_handle (h->helper_out, GNUNET_DISK_PIPE_END_READ);
423 h->fh_to_helper =
424 GNUNET_DISK_pipe_handle (h->helper_in, GNUNET_DISK_PIPE_END_WRITE);
425 h->helper_proc = GNUNET_OS_start_process_vap (h->with_control_pipe
426 ? GNUNET_OS_INHERIT_STD_ERR
427 | GNUNET_OS_USE_PIPE_CONTROL
428 : GNUNET_OS_INHERIT_STD_ERR,
429 h->helper_in,
430 h->helper_out,
431 NULL,
432 h->binary_name,
433 h->binary_argv);
434 if (NULL == h->helper_proc)
435 {
436 /* failed to start process? try again later... */
437 stop_helper (h, GNUNET_NO);
438 h->restart_task = GNUNET_SCHEDULER_add_delayed (
439 GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS,
440 h->retry_back_off),
441 &restart_task,
442 h);
443 return;
444 }
445 GNUNET_DISK_pipe_close_end (h->helper_out, GNUNET_DISK_PIPE_END_WRITE);
446 GNUNET_DISK_pipe_close_end (h->helper_in, GNUNET_DISK_PIPE_END_READ);
447 if (NULL != h->mst)
448 h->read_task = GNUNET_SCHEDULER_add_read_file (GNUNET_TIME_UNIT_FOREVER_REL,
449 h->fh_from_helper,
450 &helper_read,
451 h);
452}
453
454
455/**
456 * Restart the helper process.
457 *
458 * @param cls handle to the helper process
459 */
460static void
461restart_task (void *cls)
462{
463 struct GNUNET_HELPER_Handle *h = cls;
464
465 h->restart_task = NULL;
466 h->retry_back_off++;
467 GNUNET_log (GNUNET_ERROR_TYPE_INFO,
468 "Restarting helper with back-off %u\n",
469 h->retry_back_off);
470 start_helper (h);
471}
472
473
474/**
475 * Starts a helper and begins reading from it. The helper process is
476 * restarted when it dies except when it is stopped using GNUNET_HELPER_stop()
477 * or when the exp_cb callback is not NULL.
478 *
479 * @param with_control_pipe does the helper support the use of a control pipe for signalling?
480 * @param binary_name name of the binary to run
481 * @param binary_argv NULL-terminated list of arguments to give when starting the binary (this
482 * argument must not be modified by the client for
483 * the lifetime of the helper handle)
484 * @param cb function to call if we get messages from the helper
485 * @param exp_cb the exception callback to call. Set this to NULL if the helper
486 * process has to be restarted automatically when it dies/crashes
487 * @param cb_cls closure for the above callback
488 * @return the new Handle, NULL on error
489 */
490struct GNUNET_HELPER_Handle *
491GNUNET_HELPER_start (int with_control_pipe,
492 const char *binary_name,
493 char *const binary_argv[],
494 GNUNET_MessageTokenizerCallback cb,
495 GNUNET_HELPER_ExceptionCallback exp_cb,
496 void *cb_cls)
497{
498 struct GNUNET_HELPER_Handle *h;
499 unsigned int c;
500
501 h = GNUNET_new (struct GNUNET_HELPER_Handle);
502 h->with_control_pipe = with_control_pipe;
503 /* Lookup in libexec path only if we are starting gnunet helpers */
504 if (NULL != strstr (binary_name, "gnunet"))
505 h->binary_name = GNUNET_OS_get_libexec_binary_path (binary_name);
506 else
507 h->binary_name = GNUNET_strdup (binary_name);
508 for (c = 0; NULL != binary_argv[c]; c++)
509 ;
510 h->binary_argv = GNUNET_malloc (sizeof(char *) * (c + 1));
511 for (c = 0; NULL != binary_argv[c]; c++)
512 h->binary_argv[c] = GNUNET_strdup (binary_argv[c]);
513 h->binary_argv[c] = NULL;
514 h->cb_cls = cb_cls;
515 if (NULL != cb)
516 h->mst = GNUNET_MST_create (cb, h->cb_cls);
517 h->exp_cb = exp_cb;
518 h->retry_back_off = 0;
519 start_helper (h);
520 return h;
521}
522
523
524/**
525 * Free's the resources occupied by the helper handle
526 *
527 * @param h the helper handle to free
528 */
529void
530GNUNET_HELPER_destroy (struct GNUNET_HELPER_Handle *h)
531{
532 unsigned int c;
533 struct GNUNET_HELPER_SendHandle *sh;
534
535 if (NULL != h->write_task)
536 {
537 GNUNET_SCHEDULER_cancel (h->write_task);
538 h->write_task = NULL;
539 }
540 GNUNET_assert (NULL == h->read_task);
541 GNUNET_assert (NULL == h->restart_task);
542 while (NULL != (sh = h->sh_head))
543 {
544 GNUNET_CONTAINER_DLL_remove (h->sh_head, h->sh_tail, sh);
545 if (NULL != sh->cont)
546 sh->cont (sh->cont_cls, GNUNET_SYSERR);
547 GNUNET_free (sh);
548 }
549 if (NULL != h->mst)
550 GNUNET_MST_destroy (h->mst);
551 GNUNET_free (h->binary_name);
552 for (c = 0; h->binary_argv[c] != NULL; c++)
553 GNUNET_free (h->binary_argv[c]);
554 GNUNET_free (h->binary_argv);
555 GNUNET_free (h);
556}
557
558
559/**
560 * Kills the helper, closes the pipe and frees the handle
561 *
562 * @param h handle to helper to stop
563 * @param soft_kill if #GNUNET_YES, signals termination by closing the helper's
564 * stdin; #GNUNET_NO to signal termination by sending SIGTERM to helper
565 */
566void
567GNUNET_HELPER_stop (struct GNUNET_HELPER_Handle *h, int soft_kill)
568{
569 h->exp_cb = NULL;
570 stop_helper (h, soft_kill);
571 GNUNET_HELPER_destroy (h);
572}
573
574
575/**
576 * Write to the helper-process
577 *
578 * @param cls handle to the helper process
579 */
580static void
581helper_write (void *cls)
582{
583 struct GNUNET_HELPER_Handle *h = cls;
584 struct GNUNET_HELPER_SendHandle *sh;
585 const char *buf;
586 ssize_t t;
587
588 h->write_task = NULL;
589 if (NULL == (sh = h->sh_head))
590 {
591 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Helper write had no work!\n");
592 return; /* how did this happen? */
593 }
594 buf = (const char *) sh->msg;
595 t = GNUNET_DISK_file_write (h->fh_to_helper,
596 &buf[sh->wpos],
597 ntohs (sh->msg->size) - sh->wpos);
598 if (-1 == t)
599 {
600 /* On write-error, restart the helper */
601 GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
602 _ ("Error writing to `%s': %s\n"),
603 h->binary_name,
604 strerror (errno));
605 if (NULL != h->exp_cb)
606 {
607 h->exp_cb (h->cb_cls);
608 GNUNET_HELPER_stop (h, GNUNET_NO);
609 return;
610 }
611 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
612 "Stopping and restarting helper task!\n");
613 stop_helper (h, GNUNET_NO);
614 /* Restart the helper */
615 h->restart_task = GNUNET_SCHEDULER_add_delayed (
616 GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS,
617 h->retry_back_off),
618 &restart_task,
619 h);
620 return;
621 }
622 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
623 "Transmitted %u bytes to %s\n",
624 (unsigned int) t,
625 h->binary_name);
626 sh->wpos += t;
627 if (sh->wpos == ntohs (sh->msg->size))
628 {
629 GNUNET_CONTAINER_DLL_remove (h->sh_head, h->sh_tail, sh);
630 if (NULL != sh->cont)
631 sh->cont (sh->cont_cls, GNUNET_YES);
632 GNUNET_free (sh);
633 }
634 if (NULL != h->sh_head)
635 h->write_task =
636 GNUNET_SCHEDULER_add_write_file (GNUNET_TIME_UNIT_FOREVER_REL,
637 h->fh_to_helper,
638 &helper_write,
639 h);
640}
641
642
643/**
644 * Send an message to the helper.
645 *
646 * @param h helper to send message to
647 * @param msg message to send
648 * @param can_drop can the message be dropped if there is already one in the queue?
649 * @param cont continuation to run once the message is out (#GNUNET_OK on success, #GNUNET_NO
650 * if the helper process died, #GNUNET_SYSERR during #GNUNET_HELPER_destroy).
651 * @param cont_cls closure for @a cont
652 * @return NULL if the message was dropped,
653 * otherwise handle to cancel *cont* (actual transmission may
654 * not be abortable)
655 */
656struct GNUNET_HELPER_SendHandle *
657GNUNET_HELPER_send (struct GNUNET_HELPER_Handle *h,
658 const struct GNUNET_MessageHeader *msg,
659 int can_drop,
660 GNUNET_HELPER_Continuation cont,
661 void *cont_cls)
662{
663 struct GNUNET_HELPER_SendHandle *sh;
664 uint16_t mlen;
665
666 if (NULL == h->fh_to_helper)
667 return NULL;
668 if ((GNUNET_YES == can_drop) && (NULL != h->sh_head))
669 return NULL;
670 mlen = ntohs (msg->size);
671 sh = GNUNET_malloc (sizeof(struct GNUNET_HELPER_SendHandle) + mlen);
672 sh->msg = (const struct GNUNET_MessageHeader *) &sh[1];
673 GNUNET_memcpy (&sh[1], msg, mlen);
674 sh->h = h;
675 sh->cont = cont;
676 sh->cont_cls = cont_cls;
677 GNUNET_CONTAINER_DLL_insert_tail (h->sh_head, h->sh_tail, sh);
678 if (NULL == h->write_task)
679 h->write_task =
680 GNUNET_SCHEDULER_add_write_file (GNUNET_TIME_UNIT_FOREVER_REL,
681 h->fh_to_helper,
682 &helper_write,
683 h);
684
685 return sh;
686}
687
688
689/**
690 * Cancel a #GNUNET_HELPER_send operation. If possible, transmitting the
691 * message is also aborted, but at least 'cont' won't be
692 * called.
693 *
694 * @param sh operation to cancel
695 */
696void
697GNUNET_HELPER_send_cancel (struct GNUNET_HELPER_SendHandle *sh)
698{
699 struct GNUNET_HELPER_Handle *h = sh->h;
700
701 sh->cont = NULL;
702 sh->cont_cls = NULL;
703 if (0 == sh->wpos)
704 {
705 GNUNET_CONTAINER_DLL_remove (h->sh_head, h->sh_tail, sh);
706 GNUNET_free (sh);
707 if (NULL == h->sh_head)
708 {
709 GNUNET_SCHEDULER_cancel (h->write_task);
710 h->write_task = NULL;
711 }
712 }
713}
714
715
716/* end of helper.c */