2 This file is part of GNUnet.
3 Copyright (C) 2011, 2012 Christian Grothoff
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12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 General Public License for more details.
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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
310 restart_task (void *cls);
314 * Read from the helper-process
316 * @param cls handle to the helper process
319 helper_read (void *cls)
321 struct GNUNET_HELPER_Handle *h = cls;
322 char buf[GNUNET_SERVER_MAX_MESSAGE_SIZE] GNUNET_ALIGN;
326 t = GNUNET_DISK_file_read (h->fh_from_helper, &buf, sizeof (buf));
329 /* On read-error, restart the helper */
330 GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
331 _("Error reading from `%s': %s\n"),
334 if (NULL != h->exp_cb)
336 h->exp_cb (h->cb_cls);
337 GNUNET_HELPER_stop (h, GNUNET_NO);
340 stop_helper (h, GNUNET_NO);
341 /* Restart the helper */
342 h->restart_task = GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS,
349 /* this happens if the helper is shut down via a
350 signal, so it is not a "hard" error */
351 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
352 "Got 0 bytes from helper `%s' (EOF)\n",
354 if (NULL != h->exp_cb)
356 h->exp_cb (h->cb_cls);
357 GNUNET_HELPER_stop (h, GNUNET_NO);
360 stop_helper (h, GNUNET_NO);
361 /* Restart the helper */
363 = GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS,
368 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
369 "Got %u bytes from helper `%s'\n",
372 h->read_task = GNUNET_SCHEDULER_add_read_file (GNUNET_TIME_UNIT_FOREVER_REL,
376 GNUNET_SERVER_mst_receive (h->mst,
379 GNUNET_NO, GNUNET_NO))
381 GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
382 _("Failed to parse inbound message from helper `%s'\n"),
384 if (NULL != h->exp_cb)
386 h->exp_cb (h->cb_cls);
387 GNUNET_HELPER_stop (h, GNUNET_NO);
390 stop_helper (h, GNUNET_NO);
391 /* Restart the helper */
392 h->restart_task = GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_relative_multiply(GNUNET_TIME_UNIT_SECONDS,
401 * Start the helper process.
403 * @param h handle to the helper process
406 start_helper (struct GNUNET_HELPER_Handle *h)
408 h->helper_in = GNUNET_DISK_pipe (GNUNET_YES, GNUNET_YES, GNUNET_YES, GNUNET_NO);
409 h->helper_out = GNUNET_DISK_pipe (GNUNET_YES, GNUNET_YES, GNUNET_NO, GNUNET_YES);
410 if ( (h->helper_in == NULL) || (h->helper_out == NULL))
412 /* out of file descriptors? try again later... */
413 stop_helper (h, GNUNET_NO);
415 GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_relative_multiply(GNUNET_TIME_UNIT_SECONDS,
420 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
421 "Starting HELPER process `%s'\n",
424 GNUNET_DISK_pipe_handle (h->helper_out, GNUNET_DISK_PIPE_END_READ);
426 GNUNET_DISK_pipe_handle (h->helper_in, GNUNET_DISK_PIPE_END_WRITE);
428 GNUNET_OS_start_process_vap (h->with_control_pipe, GNUNET_OS_INHERIT_STD_ERR,
429 h->helper_in, h->helper_out, NULL,
432 if (NULL == h->helper_proc)
434 /* failed to start process? try again later... */
435 stop_helper (h, GNUNET_NO);
436 h->restart_task = GNUNET_SCHEDULER_add_delayed (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_SERVER_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++);
505 h->binary_argv = GNUNET_malloc (sizeof (char *) * (c + 1));
506 for (c = 0; NULL != binary_argv[c]; c++)
507 h->binary_argv[c] = GNUNET_strdup (binary_argv[c]);
508 h->binary_argv[c] = NULL;
511 h->mst = GNUNET_SERVER_mst_create (cb, h->cb_cls);
513 h->retry_back_off = 0;
520 * Free's the resources occupied by the helper handle
522 * @param h the helper handle to free
525 GNUNET_HELPER_destroy (struct GNUNET_HELPER_Handle *h)
528 struct GNUNET_HELPER_SendHandle *sh;
530 if (NULL != h->write_task)
532 GNUNET_SCHEDULER_cancel (h->write_task);
533 h->write_task = NULL;
535 GNUNET_assert (NULL == h->read_task);
536 GNUNET_assert (NULL == h->restart_task);
537 while (NULL != (sh = h->sh_head))
539 GNUNET_CONTAINER_DLL_remove (h->sh_head,
542 if (NULL != sh->cont)
543 sh->cont (sh->cont_cls, GNUNET_SYSERR);
547 GNUNET_SERVER_mst_destroy (h->mst);
548 GNUNET_free (h->binary_name);
549 for (c = 0; h->binary_argv[c] != NULL; c++)
550 GNUNET_free (h->binary_argv[c]);
551 GNUNET_free (h->binary_argv);
557 * Kills the helper, closes the pipe and frees the handle
559 * @param h handle to helper to stop
560 * @param soft_kill if #GNUNET_YES, signals termination by closing the helper's
561 * stdin; #GNUNET_NO to signal termination by sending SIGTERM to helper
564 GNUNET_HELPER_stop (struct GNUNET_HELPER_Handle *h,
568 stop_helper (h, soft_kill);
569 GNUNET_HELPER_destroy (h);
574 * Write to the helper-process
576 * @param cls handle to the helper process
579 helper_write (void *cls)
581 struct GNUNET_HELPER_Handle *h = cls;
582 struct GNUNET_HELPER_SendHandle *sh;
586 h->write_task = NULL;
587 if (NULL == (sh = h->sh_head))
589 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
590 "Helper write had no work!\n");
591 return; /* how did this happen? */
593 buf = (const char*) sh->msg;
594 t = GNUNET_DISK_file_write (h->fh_to_helper,
596 ntohs (sh->msg->size) - sh->wpos);
599 /* On write-error, restart the helper */
600 GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
601 _("Error writing to `%s': %s\n"),
604 if (NULL != h->exp_cb)
606 h->exp_cb (h->cb_cls);
607 GNUNET_HELPER_stop (h, GNUNET_NO);
610 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
611 "Stopping and restarting helper task!\n");
612 stop_helper (h, GNUNET_NO);
613 /* Restart the helper */
614 h->restart_task = GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_relative_multiply(GNUNET_TIME_UNIT_SECONDS,
619 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
620 "Transmitted %u bytes to %s\n",
624 if (sh->wpos == ntohs (sh->msg->size))
626 GNUNET_CONTAINER_DLL_remove (h->sh_head,
629 if (NULL != sh->cont)
630 sh->cont (sh->cont_cls, GNUNET_YES);
633 if (NULL != h->sh_head)
634 h->write_task = GNUNET_SCHEDULER_add_write_file (GNUNET_TIME_UNIT_FOREVER_REL,
642 * Send an message to the helper.
644 * @param h helper to send message to
645 * @param msg message to send
646 * @param can_drop can the message be dropped if there is already one in the queue?
647 * @param cont continuation to run once the message is out (#GNUNET_OK on succees, #GNUNET_NO
648 * if the helper process died, #GNUNET_SYSERR during #GNUNET_HELPER_destroy).
649 * @param cont_cls closure for @a cont
650 * @return NULL if the message was dropped,
651 * otherwise handle to cancel *cont* (actual transmission may
654 struct GNUNET_HELPER_SendHandle *
655 GNUNET_HELPER_send (struct GNUNET_HELPER_Handle *h,
656 const struct GNUNET_MessageHeader *msg,
658 GNUNET_HELPER_Continuation cont,
661 struct GNUNET_HELPER_SendHandle *sh;
664 if (NULL == h->fh_to_helper)
666 if ( (GNUNET_YES == can_drop) &&
667 (NULL != h->sh_head) )
669 mlen = ntohs (msg->size);
670 sh = GNUNET_malloc (sizeof (struct GNUNET_HELPER_SendHandle) + mlen);
671 sh->msg = (const struct GNUNET_MessageHeader*) &sh[1];
672 memcpy (&sh[1], msg, mlen);
675 sh->cont_cls = cont_cls;
676 GNUNET_CONTAINER_DLL_insert_tail (h->sh_head,
679 if (NULL == h->write_task)
680 h->write_task = GNUNET_SCHEDULER_add_write_file (GNUNET_TIME_UNIT_FOREVER_REL,
689 * Cancel a #GNUNET_HELPER_send operation. If possible, transmitting the
690 * message is also aborted, but at least 'cont' won't be
693 * @param sh operation to cancel
696 GNUNET_HELPER_send_cancel (struct GNUNET_HELPER_SendHandle *sh)
698 struct GNUNET_HELPER_Handle *h = sh->h;
704 GNUNET_CONTAINER_DLL_remove (h->sh_head, h->sh_tail, sh);
706 if (NULL == h->sh_head)
708 GNUNET_SCHEDULER_cancel (h->write_task);
709 h->write_task = NULL;
715 /* end of helper.c */