2 This file is part of GNUnet.
3 Copyright (C) 2011, 2012 Christian Grothoff
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.
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.
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/>.
18 SPDX-License-Identifier: AGPL3.0-or-later
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
29 #include "gnunet_util_lib.h"
30 #include "gnunet_mst_lib.h"
34 * Entry in the queue of messages we need to transmit to the helper.
36 struct GNUNET_HELPER_SendHandle {
38 * This is an entry in a DLL.
40 struct GNUNET_HELPER_SendHandle *next;
43 * This is an entry in a DLL.
45 struct GNUNET_HELPER_SendHandle *prev;
48 * Message to transmit (allocated at the end of this struct)
50 const struct GNUNET_MessageHeader *msg;
53 * The handle to a helper process.
55 struct GNUNET_HELPER_Handle *h;
58 * Function to call upon completion.
60 GNUNET_HELPER_Continuation cont;
68 * Current write position.
75 * The handle to a helper process.
77 struct GNUNET_HELPER_Handle {
79 * PipeHandle to receive data from the helper
81 struct GNUNET_DISK_PipeHandle *helper_in;
84 * PipeHandle to send data to the helper
86 struct GNUNET_DISK_PipeHandle *helper_out;
89 * FileHandle to receive data from the helper
91 const struct GNUNET_DISK_FileHandle *fh_from_helper;
94 * FileHandle to send data to the helper
96 const struct GNUNET_DISK_FileHandle *fh_to_helper;
99 * The process id of the helper
101 struct GNUNET_OS_Process *helper_proc;
104 * The Message-Tokenizer that tokenizes the messages comming from the helper
106 struct GNUNET_MessageStreamTokenizer *mst;
109 * The exception callback
111 GNUNET_HELPER_ExceptionCallback exp_cb;
114 * The closure for callbacks
119 * First message queued for transmission to helper.
121 struct GNUNET_HELPER_SendHandle *sh_head;
124 * Last message queued for transmission to helper.
126 struct GNUNET_HELPER_SendHandle *sh_tail;
134 * NULL-terminated list of command-line arguments.
139 * Task to read from the helper.
141 struct GNUNET_SCHEDULER_Task *read_task;
144 * Task to read from the helper.
146 struct GNUNET_SCHEDULER_Task *write_task;
151 struct GNUNET_SCHEDULER_Task *restart_task;
154 * Does the helper support the use of a control pipe for signalling?
156 int with_control_pipe;
159 * Count start attempts to increase linear back off
161 unsigned int retry_back_off;
166 * Sends termination signal to the helper process. The helper process is not
167 * reaped; call GNUNET_HELPER_wait() for reaping the dead helper process.
169 * @param h the helper handle
170 * @param soft_kill if GNUNET_YES, signals termination by closing the helper's
171 * stdin; GNUNET_NO to signal termination by sending SIGTERM to helper
172 * @return #GNUNET_OK on success; #GNUNET_SYSERR on error
175 GNUNET_HELPER_kill(struct GNUNET_HELPER_Handle *h, int soft_kill)
177 struct GNUNET_HELPER_SendHandle *sh;
180 while (NULL != (sh = h->sh_head))
182 GNUNET_CONTAINER_DLL_remove(h->sh_head, h->sh_tail, sh);
183 if (NULL != sh->cont)
184 sh->cont(sh->cont_cls, GNUNET_NO);
187 if (NULL != h->restart_task)
189 GNUNET_SCHEDULER_cancel(h->restart_task);
190 h->restart_task = NULL;
192 if (NULL != h->read_task)
194 GNUNET_SCHEDULER_cancel(h->read_task);
197 if (NULL == h->helper_proc)
198 return GNUNET_SYSERR;
199 if (GNUNET_YES == soft_kill)
201 /* soft-kill only possible with pipes */
202 GNUNET_assert(NULL != h->helper_in);
203 ret = GNUNET_DISK_pipe_close(h->helper_in);
205 h->fh_to_helper = NULL;
208 if (0 != GNUNET_OS_process_kill(h->helper_proc, GNUNET_TERM_SIG))
209 return GNUNET_SYSERR;
215 * Reap the helper process. This call is blocking(!). The helper process
216 * should either be sent a termination signal before or should be dead before
217 * calling this function
219 * @param h the helper handle
220 * @return #GNUNET_OK on success; #GNUNET_SYSERR on error
223 GNUNET_HELPER_wait(struct GNUNET_HELPER_Handle *h)
225 struct GNUNET_HELPER_SendHandle *sh;
229 if (NULL != h->helper_proc)
231 ret = GNUNET_OS_process_wait(h->helper_proc);
232 GNUNET_OS_process_destroy(h->helper_proc);
233 h->helper_proc = NULL;
235 if (NULL != h->read_task)
237 GNUNET_SCHEDULER_cancel(h->read_task);
240 if (NULL != h->write_task)
242 GNUNET_SCHEDULER_cancel(h->write_task);
243 h->write_task = NULL;
245 if (NULL != h->helper_in)
247 GNUNET_DISK_pipe_close(h->helper_in);
249 h->fh_to_helper = NULL;
251 if (NULL != h->helper_out)
253 GNUNET_DISK_pipe_close(h->helper_out);
254 h->helper_out = NULL;
255 h->fh_from_helper = NULL;
257 while (NULL != (sh = h->sh_head))
259 GNUNET_CONTAINER_DLL_remove(h->sh_head, h->sh_tail, sh);
260 if (NULL != sh->cont)
261 sh->cont(sh->cont_cls, GNUNET_NO);
264 /* purge MST buffer */
266 (void)GNUNET_MST_from_buffer(h->mst, NULL, 0, GNUNET_YES, GNUNET_NO);
272 * Stop the helper process, we're closing down or had an error.
274 * @param h handle to the helper process
275 * @param soft_kill if #GNUNET_YES, signals termination by closing the helper's
276 * stdin; #GNUNET_NO to signal termination by sending SIGTERM to helper
279 stop_helper(struct GNUNET_HELPER_Handle *h, int soft_kill)
281 if (NULL != h->restart_task)
283 GNUNET_SCHEDULER_cancel(h->restart_task);
284 h->restart_task = NULL;
288 GNUNET_break(GNUNET_OK == GNUNET_HELPER_kill(h, soft_kill));
289 GNUNET_break(GNUNET_OK == GNUNET_HELPER_wait(h));
295 * Restart the helper process.
297 * @param cls handle to the helper process
300 restart_task(void *cls);
304 * Read from the helper-process
306 * @param cls handle to the helper process
309 helper_read(void *cls)
311 struct GNUNET_HELPER_Handle *h = cls;
312 char buf[GNUNET_MAX_MESSAGE_SIZE] GNUNET_ALIGN;
316 t = GNUNET_DISK_file_read(h->fh_from_helper, &buf, sizeof(buf));
319 /* On read-error, restart the helper */
320 GNUNET_log(GNUNET_ERROR_TYPE_WARNING,
321 _("Error reading from `%s': %s\n"),
324 if (NULL != h->exp_cb)
326 h->exp_cb(h->cb_cls);
327 GNUNET_HELPER_stop(h, GNUNET_NO);
330 stop_helper(h, GNUNET_NO);
331 /* Restart the helper */
332 h->restart_task = GNUNET_SCHEDULER_add_delayed(
333 GNUNET_TIME_relative_multiply(GNUNET_TIME_UNIT_SECONDS,
341 /* this happens if the helper is shut down via a
342 signal, so it is not a "hard" error */
343 GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
344 "Got 0 bytes from helper `%s' (EOF)\n",
346 if (NULL != h->exp_cb)
348 h->exp_cb(h->cb_cls);
349 GNUNET_HELPER_stop(h, GNUNET_NO);
352 stop_helper(h, GNUNET_NO);
353 /* Restart the helper */
354 h->restart_task = GNUNET_SCHEDULER_add_delayed(
355 GNUNET_TIME_relative_multiply(GNUNET_TIME_UNIT_SECONDS,
361 GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
362 "Got %u bytes from helper `%s'\n",
365 h->read_task = GNUNET_SCHEDULER_add_read_file(GNUNET_TIME_UNIT_FOREVER_REL,
370 GNUNET_MST_from_buffer(h->mst, buf, t, GNUNET_NO, GNUNET_NO))
372 GNUNET_log(GNUNET_ERROR_TYPE_WARNING,
373 _("Failed to parse inbound message from helper `%s'\n"),
375 if (NULL != h->exp_cb)
377 h->exp_cb(h->cb_cls);
378 GNUNET_HELPER_stop(h, GNUNET_NO);
381 stop_helper(h, GNUNET_NO);
382 /* Restart the helper */
383 h->restart_task = GNUNET_SCHEDULER_add_delayed(
384 GNUNET_TIME_relative_multiply(GNUNET_TIME_UNIT_SECONDS,
394 * Start the helper process.
396 * @param h handle to the helper process
399 start_helper(struct GNUNET_HELPER_Handle *h)
402 GNUNET_DISK_pipe(GNUNET_YES, GNUNET_YES, GNUNET_YES, GNUNET_NO);
404 GNUNET_DISK_pipe(GNUNET_YES, GNUNET_YES, GNUNET_NO, GNUNET_YES);
405 if ((h->helper_in == NULL) || (h->helper_out == NULL))
407 /* out of file descriptors? try again later... */
408 stop_helper(h, GNUNET_NO);
409 h->restart_task = GNUNET_SCHEDULER_add_delayed(
410 GNUNET_TIME_relative_multiply(GNUNET_TIME_UNIT_SECONDS,
416 GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
417 "Starting HELPER process `%s'\n",
420 GNUNET_DISK_pipe_handle(h->helper_out, GNUNET_DISK_PIPE_END_READ);
422 GNUNET_DISK_pipe_handle(h->helper_in, GNUNET_DISK_PIPE_END_WRITE);
423 h->helper_proc = GNUNET_OS_start_process_vap(h->with_control_pipe,
424 GNUNET_OS_INHERIT_STD_ERR,
430 if (NULL == h->helper_proc)
432 /* failed to start process? try again later... */
433 stop_helper(h, GNUNET_NO);
434 h->restart_task = GNUNET_SCHEDULER_add_delayed(
435 GNUNET_TIME_relative_multiply(GNUNET_TIME_UNIT_SECONDS,
441 GNUNET_DISK_pipe_close_end(h->helper_out, GNUNET_DISK_PIPE_END_WRITE);
442 GNUNET_DISK_pipe_close_end(h->helper_in, GNUNET_DISK_PIPE_END_READ);
444 h->read_task = GNUNET_SCHEDULER_add_read_file(GNUNET_TIME_UNIT_FOREVER_REL,
452 * Restart the helper process.
454 * @param cls handle to the helper process
457 restart_task(void *cls)
459 struct GNUNET_HELPER_Handle *h = cls;
461 h->restart_task = NULL;
463 GNUNET_log(GNUNET_ERROR_TYPE_INFO,
464 "Restarting helper with back-off %u\n",
471 * Starts a helper and begins reading from it. The helper process is
472 * restarted when it dies except when it is stopped using GNUNET_HELPER_stop()
473 * or when the exp_cb callback is not NULL.
475 * @param with_control_pipe does the helper support the use of a control pipe for signalling?
476 * @param binary_name name of the binary to run
477 * @param binary_argv NULL-terminated list of arguments to give when starting the binary (this
478 * argument must not be modified by the client for
479 * the lifetime of the helper handle)
480 * @param cb function to call if we get messages from the helper
481 * @param exp_cb the exception callback to call. Set this to NULL if the helper
482 * process has to be restarted automatically when it dies/crashes
483 * @param cb_cls closure for the above callback
484 * @return the new Handle, NULL on error
486 struct GNUNET_HELPER_Handle *
487 GNUNET_HELPER_start(int with_control_pipe,
488 const char *binary_name,
489 char *const binary_argv[],
490 GNUNET_MessageTokenizerCallback cb,
491 GNUNET_HELPER_ExceptionCallback exp_cb,
494 struct GNUNET_HELPER_Handle *h;
497 h = GNUNET_new(struct GNUNET_HELPER_Handle);
498 h->with_control_pipe = with_control_pipe;
499 /* Lookup in libexec path only if we are starting gnunet helpers */
500 if (NULL != strstr(binary_name, "gnunet"))
501 h->binary_name = GNUNET_OS_get_libexec_binary_path(binary_name);
503 h->binary_name = GNUNET_strdup(binary_name);
504 for (c = 0; NULL != binary_argv[c]; c++)
506 h->binary_argv = GNUNET_malloc(sizeof(char *) * (c + 1));
507 for (c = 0; NULL != binary_argv[c]; c++)
508 h->binary_argv[c] = GNUNET_strdup(binary_argv[c]);
509 h->binary_argv[c] = NULL;
512 h->mst = GNUNET_MST_create(cb, h->cb_cls);
514 h->retry_back_off = 0;
521 * Free's the resources occupied by the helper handle
523 * @param h the helper handle to free
526 GNUNET_HELPER_destroy(struct GNUNET_HELPER_Handle *h)
529 struct GNUNET_HELPER_SendHandle *sh;
531 if (NULL != h->write_task)
533 GNUNET_SCHEDULER_cancel(h->write_task);
534 h->write_task = NULL;
536 GNUNET_assert(NULL == h->read_task);
537 GNUNET_assert(NULL == h->restart_task);
538 while (NULL != (sh = h->sh_head))
540 GNUNET_CONTAINER_DLL_remove(h->sh_head, h->sh_tail, sh);
541 if (NULL != sh->cont)
542 sh->cont(sh->cont_cls, GNUNET_SYSERR);
546 GNUNET_MST_destroy(h->mst);
547 GNUNET_free(h->binary_name);
548 for (c = 0; h->binary_argv[c] != NULL; c++)
549 GNUNET_free(h->binary_argv[c]);
550 GNUNET_free(h->binary_argv);
556 * Kills the helper, closes the pipe and frees the handle
558 * @param h handle to helper to stop
559 * @param soft_kill if #GNUNET_YES, signals termination by closing the helper's
560 * stdin; #GNUNET_NO to signal termination by sending SIGTERM to helper
563 GNUNET_HELPER_stop(struct GNUNET_HELPER_Handle *h, int soft_kill)
566 stop_helper(h, soft_kill);
567 GNUNET_HELPER_destroy(h);
572 * Write to the helper-process
574 * @param cls handle to the helper process
577 helper_write(void *cls)
579 struct GNUNET_HELPER_Handle *h = cls;
580 struct GNUNET_HELPER_SendHandle *sh;
584 h->write_task = NULL;
585 if (NULL == (sh = h->sh_head))
587 GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Helper write had no work!\n");
588 return; /* how did this happen? */
590 buf = (const char *)sh->msg;
591 t = GNUNET_DISK_file_write(h->fh_to_helper,
593 ntohs(sh->msg->size) - sh->wpos);
596 /* On write-error, restart the helper */
597 GNUNET_log(GNUNET_ERROR_TYPE_WARNING,
598 _("Error writing to `%s': %s\n"),
601 if (NULL != h->exp_cb)
603 h->exp_cb(h->cb_cls);
604 GNUNET_HELPER_stop(h, GNUNET_NO);
607 GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
608 "Stopping and restarting helper task!\n");
609 stop_helper(h, GNUNET_NO);
610 /* Restart the helper */
611 h->restart_task = GNUNET_SCHEDULER_add_delayed(
612 GNUNET_TIME_relative_multiply(GNUNET_TIME_UNIT_SECONDS,
618 GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
619 "Transmitted %u bytes to %s\n",
623 if (sh->wpos == ntohs(sh->msg->size))
625 GNUNET_CONTAINER_DLL_remove(h->sh_head, h->sh_tail, sh);
626 if (NULL != sh->cont)
627 sh->cont(sh->cont_cls, GNUNET_YES);
630 if (NULL != h->sh_head)
632 GNUNET_SCHEDULER_add_write_file(GNUNET_TIME_UNIT_FOREVER_REL,
640 * Send an message to the helper.
642 * @param h helper to send message to
643 * @param msg message to send
644 * @param can_drop can the message be dropped if there is already one in the queue?
645 * @param cont continuation to run once the message is out (#GNUNET_OK on succees, #GNUNET_NO
646 * if the helper process died, #GNUNET_SYSERR during #GNUNET_HELPER_destroy).
647 * @param cont_cls closure for @a cont
648 * @return NULL if the message was dropped,
649 * otherwise handle to cancel *cont* (actual transmission may
652 struct GNUNET_HELPER_SendHandle *
653 GNUNET_HELPER_send(struct GNUNET_HELPER_Handle *h,
654 const struct GNUNET_MessageHeader *msg,
656 GNUNET_HELPER_Continuation cont,
659 struct GNUNET_HELPER_SendHandle *sh;
662 if (NULL == h->fh_to_helper)
664 if ((GNUNET_YES == can_drop) && (NULL != h->sh_head))
666 mlen = ntohs(msg->size);
667 sh = GNUNET_malloc(sizeof(struct GNUNET_HELPER_SendHandle) + mlen);
668 sh->msg = (const struct GNUNET_MessageHeader *)&sh[1];
669 GNUNET_memcpy(&sh[1], msg, mlen);
672 sh->cont_cls = cont_cls;
673 GNUNET_CONTAINER_DLL_insert_tail(h->sh_head, h->sh_tail, sh);
674 if (NULL == h->write_task)
676 GNUNET_SCHEDULER_add_write_file(GNUNET_TIME_UNIT_FOREVER_REL,
685 * Cancel a #GNUNET_HELPER_send operation. If possible, transmitting the
686 * message is also aborted, but at least 'cont' won't be
689 * @param sh operation to cancel
692 GNUNET_HELPER_send_cancel(struct GNUNET_HELPER_SendHandle *sh)
694 struct GNUNET_HELPER_Handle *h = sh->h;
700 GNUNET_CONTAINER_DLL_remove(h->sh_head, h->sh_tail, sh);
702 if (NULL == h->sh_head)
704 GNUNET_SCHEDULER_cancel(h->write_task);
705 h->write_task = NULL;
711 /* end of helper.c */