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
6 it under the terms of the GNU General Public License as published
7 by the Free Software Foundation; either version 3, or (at your
8 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 General Public License for more details.
15 You should have received a copy of the GNU General Public License
16 along with GNUnet; see the file COPYING. If not, write to the
17 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
18 Boston, MA 02110-1301, USA.
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"
33 * Entry in the queue of messages we need to transmit to the helper.
35 struct GNUNET_HELPER_SendHandle
39 * This is an entry in a DLL.
41 struct GNUNET_HELPER_SendHandle *next;
44 * This is an entry in a DLL.
46 struct GNUNET_HELPER_SendHandle *prev;
49 * Message to transmit (allocated at the end of this struct)
51 const struct GNUNET_MessageHeader *msg;
54 * The handle to a helper process.
56 struct GNUNET_HELPER_Handle *h;
59 * Function to call upon completion.
61 GNUNET_HELPER_Continuation cont;
69 * Current write position.
77 * The handle to a helper process.
79 struct GNUNET_HELPER_Handle
83 * PipeHandle to receive data from the helper
85 struct GNUNET_DISK_PipeHandle *helper_in;
88 * PipeHandle to send data to the helper
90 struct GNUNET_DISK_PipeHandle *helper_out;
93 * FileHandle to receive data from the helper
95 const struct GNUNET_DISK_FileHandle *fh_from_helper;
98 * FileHandle to send data to the helper
100 const struct GNUNET_DISK_FileHandle *fh_to_helper;
103 * The process id of the helper
105 struct GNUNET_OS_Process *helper_proc;
108 * The Message-Tokenizer that tokenizes the messages comming from the helper
110 struct GNUNET_SERVER_MessageStreamTokenizer *mst;
113 * The exception callback
115 GNUNET_HELPER_ExceptionCallback exp_cb;
118 * The closure for callbacks
123 * First message queued for transmission to helper.
125 struct GNUNET_HELPER_SendHandle *sh_head;
128 * Last message queued for transmission to helper.
130 struct GNUNET_HELPER_SendHandle *sh_tail;
138 * NULL-terminated list of command-line arguments.
143 * Task to read from the helper.
145 struct GNUNET_SCHEDULER_Task * read_task;
148 * Task to read from the helper.
150 struct GNUNET_SCHEDULER_Task * write_task;
155 struct GNUNET_SCHEDULER_Task * restart_task;
158 * Does the helper support the use of a control pipe for signalling?
160 int with_control_pipe;
163 * Count start attempts to increase linear back off
165 unsigned int retry_back_off;
170 * Sends termination signal to the helper process. The helper process is not
171 * reaped; call GNUNET_HELPER_wait() for reaping the dead helper process.
173 * @param h the helper handle
174 * @param soft_kill if GNUNET_YES, signals termination by closing the helper's
175 * stdin; GNUNET_NO to signal termination by sending SIGTERM to helper
176 * @return #GNUNET_OK on success; #GNUNET_SYSERR on error
179 GNUNET_HELPER_kill (struct GNUNET_HELPER_Handle *h,
182 struct GNUNET_HELPER_SendHandle *sh;
185 while (NULL != (sh = h->sh_head))
187 GNUNET_CONTAINER_DLL_remove (h->sh_head,
190 if (NULL != sh->cont)
191 sh->cont (sh->cont_cls, GNUNET_NO);
194 if (NULL != h->restart_task)
196 GNUNET_SCHEDULER_cancel (h->restart_task);
197 h->restart_task = NULL;
199 if (NULL != h->read_task)
201 GNUNET_SCHEDULER_cancel (h->read_task);
204 if (NULL == h->helper_proc)
205 return GNUNET_SYSERR;
206 if (GNUNET_YES == soft_kill)
208 /* soft-kill only possible with pipes */
209 GNUNET_assert (NULL != h->helper_in);
210 ret = GNUNET_DISK_pipe_close (h->helper_in);
212 h->fh_to_helper = NULL;
215 if (0 != GNUNET_OS_process_kill (h->helper_proc, GNUNET_TERM_SIG))
216 return GNUNET_SYSERR;
222 * Reap the helper process. This call is blocking(!). The helper process
223 * should either be sent a termination signal before or should be dead before
224 * calling this function
226 * @param h the helper handle
227 * @return #GNUNET_OK on success; #GNUNET_SYSERR on error
230 GNUNET_HELPER_wait (struct GNUNET_HELPER_Handle *h)
232 struct GNUNET_HELPER_SendHandle *sh;
236 if (NULL != h->helper_proc)
238 ret = GNUNET_OS_process_wait (h->helper_proc);
239 GNUNET_OS_process_destroy (h->helper_proc);
240 h->helper_proc = NULL;
242 if (NULL != h->read_task)
244 GNUNET_SCHEDULER_cancel (h->read_task);
247 if (NULL != h->write_task)
249 GNUNET_SCHEDULER_cancel (h->write_task);
250 h->write_task = NULL;
252 if (NULL != h->helper_in)
254 GNUNET_DISK_pipe_close (h->helper_in);
256 h->fh_to_helper = NULL;
258 if (NULL != h->helper_out)
260 GNUNET_DISK_pipe_close (h->helper_out);
261 h->helper_out = NULL;
262 h->fh_from_helper = NULL;
264 while (NULL != (sh = h->sh_head))
266 GNUNET_CONTAINER_DLL_remove (h->sh_head,
269 if (NULL != sh->cont)
270 sh->cont (sh->cont_cls, GNUNET_NO);
273 /* purge MST buffer */
275 (void) GNUNET_SERVER_mst_receive (h->mst, NULL, NULL, 0, GNUNET_YES, GNUNET_NO);
281 * Stop the helper process, we're closing down or had an error.
283 * @param h handle to the helper process
284 * @param soft_kill if #GNUNET_YES, signals termination by closing the helper's
285 * stdin; #GNUNET_NO to signal termination by sending SIGTERM to helper
288 stop_helper (struct GNUNET_HELPER_Handle *h,
291 if (NULL != h->restart_task)
293 GNUNET_SCHEDULER_cancel (h->restart_task);
294 h->restart_task = NULL;
298 GNUNET_break (GNUNET_OK == GNUNET_HELPER_kill (h, soft_kill));
299 GNUNET_break (GNUNET_OK == GNUNET_HELPER_wait (h));
305 * Restart the helper process.
307 * @param cls handle to the helper process
308 * @param tc scheduler context
311 restart_task (void *cls,
312 const struct GNUNET_SCHEDULER_TaskContext *tc);
316 * Read from the helper-process
318 * @param cls handle to the helper process
319 * @param tc scheduler context
322 helper_read (void *cls,
323 const struct GNUNET_SCHEDULER_TaskContext *tc)
325 struct GNUNET_HELPER_Handle *h = cls;
326 char buf[GNUNET_SERVER_MAX_MESSAGE_SIZE] GNUNET_ALIGN;
330 if (0 != (tc->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN))
333 h->read_task = GNUNET_SCHEDULER_add_read_file (GNUNET_TIME_UNIT_FOREVER_REL,
334 h->fh_from_helper, &helper_read, h);
337 t = GNUNET_DISK_file_read (h->fh_from_helper, &buf, sizeof (buf));
340 /* On read-error, restart the helper */
341 GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
342 _("Error reading from `%s': %s\n"),
345 if (NULL != h->exp_cb)
347 h->exp_cb (h->cb_cls);
348 GNUNET_HELPER_stop (h, GNUNET_NO);
351 stop_helper (h, GNUNET_NO);
352 /* Restart the helper */
353 h->restart_task = GNUNET_SCHEDULER_add_delayed(
354 GNUNET_TIME_relative_multiply(GNUNET_TIME_UNIT_SECONDS,
355 h->retry_back_off), &restart_task, h);
360 /* this happens if the helper is shut down via a
361 signal, so it is not a "hard" error */
362 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
363 "Got 0 bytes from helper `%s' (EOF)\n",
365 if (NULL != h->exp_cb)
367 h->exp_cb (h->cb_cls);
368 GNUNET_HELPER_stop (h, GNUNET_NO);
371 stop_helper (h, GNUNET_NO);
372 /* Restart the helper */
373 h->restart_task = GNUNET_SCHEDULER_add_delayed(
374 GNUNET_TIME_relative_multiply(GNUNET_TIME_UNIT_SECONDS,
375 h->retry_back_off), &restart_task, h);
378 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
379 "Got %u bytes from helper `%s'\n",
382 h->read_task = GNUNET_SCHEDULER_add_read_file (GNUNET_TIME_UNIT_FOREVER_REL,
383 h->fh_from_helper, &helper_read, h);
385 GNUNET_SERVER_mst_receive (h->mst, NULL, buf, t, GNUNET_NO, GNUNET_NO))
387 GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
388 _("Failed to parse inbound message from helper `%s'\n"),
390 if (NULL != h->exp_cb)
392 h->exp_cb (h->cb_cls);
393 GNUNET_HELPER_stop (h, GNUNET_NO);
396 stop_helper (h, GNUNET_NO);
397 /* Restart the helper */
398 h->restart_task = GNUNET_SCHEDULER_add_delayed(
399 GNUNET_TIME_relative_multiply(GNUNET_TIME_UNIT_SECONDS,
400 h->retry_back_off), &restart_task, h);
407 * Start the helper process.
409 * @param h handle to the helper process
412 start_helper (struct GNUNET_HELPER_Handle *h)
414 h->helper_in = GNUNET_DISK_pipe (GNUNET_YES, GNUNET_YES, GNUNET_YES, GNUNET_NO);
415 h->helper_out = GNUNET_DISK_pipe (GNUNET_YES, GNUNET_YES, GNUNET_NO, GNUNET_YES);
416 if ( (h->helper_in == NULL) || (h->helper_out == NULL))
418 /* out of file descriptors? try again later... */
419 stop_helper (h, GNUNET_NO);
421 GNUNET_SCHEDULER_add_delayed(
422 GNUNET_TIME_relative_multiply(GNUNET_TIME_UNIT_SECONDS,
423 h->retry_back_off), &restart_task, h);
426 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
427 "Starting HELPER process `%s'\n",
430 GNUNET_DISK_pipe_handle (h->helper_out, GNUNET_DISK_PIPE_END_READ);
432 GNUNET_DISK_pipe_handle (h->helper_in, GNUNET_DISK_PIPE_END_WRITE);
434 GNUNET_OS_start_process_vap (h->with_control_pipe, GNUNET_OS_INHERIT_STD_ERR,
435 h->helper_in, h->helper_out, NULL,
438 if (NULL == h->helper_proc)
440 /* failed to start process? try again later... */
441 stop_helper (h, GNUNET_NO);
442 h->restart_task = GNUNET_SCHEDULER_add_delayed(
443 GNUNET_TIME_relative_multiply(GNUNET_TIME_UNIT_SECONDS,
444 h->retry_back_off), &restart_task, h);
447 GNUNET_DISK_pipe_close_end (h->helper_out, GNUNET_DISK_PIPE_END_WRITE);
448 GNUNET_DISK_pipe_close_end (h->helper_in, GNUNET_DISK_PIPE_END_READ);
450 h->read_task = GNUNET_SCHEDULER_add_read_file (GNUNET_TIME_UNIT_FOREVER_REL,
458 * Restart the helper process.
460 * @param cls handle to the helper process
461 * @param tc scheduler context
464 restart_task (void *cls,
465 const struct GNUNET_SCHEDULER_TaskContext *tc)
467 struct GNUNET_HELPER_Handle*h = cls;
469 h->restart_task = NULL;
471 GNUNET_log (GNUNET_ERROR_TYPE_INFO,
472 "Restarting helper with back-off %u\n",
479 * Starts a helper and begins reading from it. The helper process is
480 * restarted when it dies except when it is stopped using GNUNET_HELPER_stop()
481 * or when the exp_cb callback is not NULL.
483 * @param with_control_pipe does the helper support the use of a control pipe for signalling?
484 * @param binary_name name of the binary to run
485 * @param binary_argv NULL-terminated list of arguments to give when starting the binary (this
486 * argument must not be modified by the client for
487 * the lifetime of the helper handle)
488 * @param cb function to call if we get messages from the helper
489 * @param exp_cb the exception callback to call. Set this to NULL if the helper
490 * process has to be restarted automatically when it dies/crashes
491 * @param cb_cls closure for the above callback
492 * @return the new Handle, NULL on error
494 struct GNUNET_HELPER_Handle *
495 GNUNET_HELPER_start (int with_control_pipe,
496 const char *binary_name,
497 char *const binary_argv[],
498 GNUNET_SERVER_MessageTokenizerCallback cb,
499 GNUNET_HELPER_ExceptionCallback exp_cb,
502 struct GNUNET_HELPER_Handle *h;
505 h = GNUNET_new (struct GNUNET_HELPER_Handle);
506 h->with_control_pipe = with_control_pipe;
507 /* Lookup in libexec path only if we are starting gnunet helpers */
508 if (NULL != strstr (binary_name, "gnunet"))
509 h->binary_name = GNUNET_OS_get_libexec_binary_path (binary_name);
511 h->binary_name = GNUNET_strdup (binary_name);
512 for (c = 0; NULL != binary_argv[c]; c++);
513 h->binary_argv = GNUNET_malloc (sizeof (char *) * (c + 1));
514 for (c = 0; NULL != binary_argv[c]; c++)
515 h->binary_argv[c] = GNUNET_strdup (binary_argv[c]);
516 h->binary_argv[c] = NULL;
519 h->mst = GNUNET_SERVER_mst_create (cb, h->cb_cls);
521 h->retry_back_off = 0;
528 * Free's the resources occupied by the helper handle
530 * @param h the helper handle to free
533 GNUNET_HELPER_destroy (struct GNUNET_HELPER_Handle *h)
536 struct GNUNET_HELPER_SendHandle *sh;
538 if (NULL != h->write_task)
540 GNUNET_SCHEDULER_cancel (h->write_task);
541 h->write_task = NULL;
543 GNUNET_assert (NULL == h->read_task);
544 GNUNET_assert (NULL == h->restart_task);
545 while (NULL != (sh = h->sh_head))
547 GNUNET_CONTAINER_DLL_remove (h->sh_head,
550 if (NULL != sh->cont)
551 sh->cont (sh->cont_cls, GNUNET_SYSERR);
555 GNUNET_SERVER_mst_destroy (h->mst);
556 GNUNET_free (h->binary_name);
557 for (c = 0; h->binary_argv[c] != NULL; c++)
558 GNUNET_free (h->binary_argv[c]);
559 GNUNET_free (h->binary_argv);
565 * Kills the helper, closes the pipe and frees the handle
567 * @param h handle to helper to stop
568 * @param soft_kill if #GNUNET_YES, signals termination by closing the helper's
569 * stdin; #GNUNET_NO to signal termination by sending SIGTERM to helper
572 GNUNET_HELPER_stop (struct GNUNET_HELPER_Handle *h,
576 stop_helper (h, soft_kill);
577 GNUNET_HELPER_destroy (h);
582 * Write to the helper-process
584 * @param cls handle to the helper process
585 * @param tc scheduler context
588 helper_write (void *cls,
589 const struct GNUNET_SCHEDULER_TaskContext *tc)
591 struct GNUNET_HELPER_Handle *h = cls;
592 struct GNUNET_HELPER_SendHandle *sh;
596 h->write_task = NULL;
597 if (0 != (tc->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN))
600 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
601 "Helper write triggered during shutdown, retrying\n");
602 h->write_task = GNUNET_SCHEDULER_add_write_file (GNUNET_TIME_UNIT_FOREVER_REL,
603 h->fh_to_helper, &helper_write, h);
606 if (NULL == (sh = h->sh_head))
608 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
609 "Helper write had no work!\n");
610 return; /* how did this happen? */
612 buf = (const char*) sh->msg;
613 t = GNUNET_DISK_file_write (h->fh_to_helper,
615 ntohs (sh->msg->size) - sh->wpos);
618 /* On write-error, restart the helper */
619 GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
620 _("Error writing to `%s': %s\n"),
623 if (NULL != h->exp_cb)
625 h->exp_cb (h->cb_cls);
626 GNUNET_HELPER_stop (h, GNUNET_NO);
629 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
630 "Stopping and restarting helper task!\n");
631 stop_helper (h, GNUNET_NO);
632 /* Restart the helper */
633 h->restart_task = GNUNET_SCHEDULER_add_delayed(
634 GNUNET_TIME_relative_multiply(GNUNET_TIME_UNIT_SECONDS,
635 h->retry_back_off), &restart_task, h);
638 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
639 "Transmitted %u bytes to %s\n",
643 if (sh->wpos == ntohs (sh->msg->size))
645 GNUNET_CONTAINER_DLL_remove (h->sh_head,
648 if (NULL != sh->cont)
649 sh->cont (sh->cont_cls, GNUNET_YES);
652 if (NULL != h->sh_head)
653 h->write_task = GNUNET_SCHEDULER_add_write_file (GNUNET_TIME_UNIT_FOREVER_REL,
661 * Send an message to the helper.
663 * @param h helper to send message to
664 * @param msg message to send
665 * @param can_drop can the message be dropped if there is already one in the queue?
666 * @param cont continuation to run once the message is out (#GNUNET_OK on succees, #GNUNET_NO
667 * if the helper process died, #GNUNET_SYSERR during #GNUNET_HELPER_destroy).
668 * @param cont_cls closure for @a cont
669 * @return NULL if the message was dropped,
670 * otherwise handle to cancel *cont* (actual transmission may
673 struct GNUNET_HELPER_SendHandle *
674 GNUNET_HELPER_send (struct GNUNET_HELPER_Handle *h,
675 const struct GNUNET_MessageHeader *msg,
677 GNUNET_HELPER_Continuation cont,
680 struct GNUNET_HELPER_SendHandle *sh;
683 if (NULL == h->fh_to_helper)
685 if ( (GNUNET_YES == can_drop) &&
686 (NULL != h->sh_head) )
688 mlen = ntohs (msg->size);
689 sh = GNUNET_malloc (sizeof (struct GNUNET_HELPER_SendHandle) + mlen);
690 sh->msg = (const struct GNUNET_MessageHeader*) &sh[1];
691 memcpy (&sh[1], msg, mlen);
694 sh->cont_cls = cont_cls;
695 GNUNET_CONTAINER_DLL_insert_tail (h->sh_head,
698 if (NULL == h->write_task)
699 h->write_task = GNUNET_SCHEDULER_add_write_file (GNUNET_TIME_UNIT_FOREVER_REL,
708 * Cancel a #GNUNET_HELPER_send operation. If possible, transmitting the
709 * message is also aborted, but at least 'cont' won't be
712 * @param sh operation to cancel
715 GNUNET_HELPER_send_cancel (struct GNUNET_HELPER_SendHandle *sh)
717 struct GNUNET_HELPER_Handle *h = sh->h;
723 GNUNET_CONTAINER_DLL_remove (h->sh_head, h->sh_tail, sh);
725 if (NULL == h->sh_head)
727 GNUNET_SCHEDULER_cancel (h->write_task);
728 h->write_task = NULL;
734 /* end of helper.c */