2 This file is part of GNUnet.
3 (C) 2011, 2012 Christian Grothoff
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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 GNUNET_SCHEDULER_TaskIdentifier read_task;
148 * Task to read from the helper.
150 GNUNET_SCHEDULER_TaskIdentifier write_task;
155 GNUNET_SCHEDULER_TaskIdentifier restart_task;
158 * Does the helper support the use of a control pipe for signalling?
160 int with_control_pipe;
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,
185 if (NULL != sh->cont)
186 sh->cont (sh->cont_cls, GNUNET_NO);
189 if (GNUNET_SCHEDULER_NO_TASK != h->restart_task)
191 GNUNET_SCHEDULER_cancel (h->restart_task);
192 h->restart_task = GNUNET_SCHEDULER_NO_TASK;
194 if (NULL == h->helper_proc)
195 return GNUNET_SYSERR;
196 if (GNUNET_YES == soft_kill)
198 /* soft-kill only possible with pipes */
199 GNUNET_assert (NULL != h->helper_in);
200 ret = GNUNET_DISK_pipe_close (h->helper_in);
202 h->fh_to_helper = NULL;
205 if (0 != GNUNET_OS_process_kill (h->helper_proc, SIGTERM))
206 return GNUNET_SYSERR;
212 * Reap the helper process. This call is blocking(!). The helper process
213 * should either be sent a termination signal before or should be dead before
214 * calling this function
216 * @param h the helper handle
217 * @return GNUNET_OK on success; GNUNET_SYSERR on error
220 GNUNET_HELPER_wait (struct GNUNET_HELPER_Handle *h)
222 struct GNUNET_HELPER_SendHandle *sh;
225 if (NULL != h->helper_proc)
227 ret = GNUNET_OS_process_wait (h->helper_proc);
228 GNUNET_OS_process_destroy (h->helper_proc);
229 h->helper_proc = NULL;
231 if (GNUNET_SCHEDULER_NO_TASK != h->read_task)
233 GNUNET_SCHEDULER_cancel (h->read_task);
234 h->read_task = GNUNET_SCHEDULER_NO_TASK;
236 if (GNUNET_SCHEDULER_NO_TASK != h->write_task)
238 GNUNET_SCHEDULER_cancel (h->write_task);
239 h->write_task = GNUNET_SCHEDULER_NO_TASK;
241 if (NULL != h->helper_in)
243 GNUNET_DISK_pipe_close (h->helper_in);
245 h->fh_to_helper = NULL;
247 if (NULL != h->helper_out)
249 GNUNET_DISK_pipe_close (h->helper_out);
250 h->helper_out = NULL;
251 h->fh_from_helper = NULL;
253 while (NULL != (sh = h->sh_head))
255 GNUNET_CONTAINER_DLL_remove (h->sh_head,
258 if (NULL != sh->cont)
259 sh->cont (sh->cont_cls, GNUNET_NO);
262 /* purge MST buffer */
263 (void) GNUNET_SERVER_mst_receive (h->mst, NULL, NULL, 0, GNUNET_YES, GNUNET_NO);
269 * Stop the helper process, we're closing down or had an error.
271 * @param h handle to the helper process
272 * @param soft_kill if GNUNET_YES, signals termination by closing the helper's
273 * stdin; GNUNET_NO to signal termination by sending SIGTERM to helper
276 stop_helper (struct GNUNET_HELPER_Handle *h, int soft_kill)
278 GNUNET_break (GNUNET_OK == GNUNET_HELPER_kill (h, soft_kill));
279 GNUNET_break (GNUNET_OK == GNUNET_HELPER_wait (h));
284 * Restart the helper process.
286 * @param cls handle to the helper process
287 * @param tc scheduler context
290 restart_task (void *cls,
291 const struct GNUNET_SCHEDULER_TaskContext *tc);
295 * Read from the helper-process
297 * @param cls handle to the helper process
298 * @param tc scheduler context
301 helper_read (void *cls,
302 const struct GNUNET_SCHEDULER_TaskContext *tc)
304 struct GNUNET_HELPER_Handle *h = cls;
305 char buf[GNUNET_SERVER_MAX_MESSAGE_SIZE] GNUNET_ALIGN;
308 h->read_task = GNUNET_SCHEDULER_NO_TASK;
309 if (0 != (tc->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN))
312 h->read_task = GNUNET_SCHEDULER_add_read_file (GNUNET_TIME_UNIT_FOREVER_REL,
313 h->fh_from_helper, &helper_read, h);
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 */
333 GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_UNIT_SECONDS, &restart_task, h);
338 /* this happens if the helper is shut down via a
339 signal, so it is not a "hard" error */
340 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
341 "Got 0 bytes from helper `%s' (EOF)\n",
343 if (NULL != h->exp_cb)
345 h->exp_cb (h->cb_cls);
346 GNUNET_HELPER_stop (h, GNUNET_NO);
349 stop_helper (h, GNUNET_NO);
350 /* Restart the helper */
352 GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_UNIT_SECONDS,
356 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
357 "Got %u bytes from helper `%s'\n",
360 h->read_task = GNUNET_SCHEDULER_add_read_file (GNUNET_TIME_UNIT_FOREVER_REL,
361 h->fh_from_helper, &helper_read, h);
363 GNUNET_SERVER_mst_receive (h->mst, NULL, buf, t, GNUNET_NO, GNUNET_NO))
365 GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
366 _("Failed to parse inbound message from helper `%s'\n"),
368 if (NULL != h->exp_cb)
370 h->exp_cb (h->cb_cls);
371 GNUNET_HELPER_stop (h, GNUNET_NO);
374 stop_helper (h, GNUNET_NO);
375 /* Restart the helper */
377 GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_UNIT_SECONDS,
385 * Start the helper process.
387 * @param h handle to the helper process
390 start_helper (struct GNUNET_HELPER_Handle *h)
392 h->helper_in = GNUNET_DISK_pipe (GNUNET_YES, GNUNET_YES, GNUNET_YES, GNUNET_NO);
393 h->helper_out = GNUNET_DISK_pipe (GNUNET_YES, GNUNET_YES, GNUNET_NO, GNUNET_YES);
394 if ( (h->helper_in == NULL) || (h->helper_out == NULL))
396 /* out of file descriptors? try again later... */
397 stop_helper (h, GNUNET_NO);
399 GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_UNIT_SECONDS,
403 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
404 "Starting HELPER process `%s'\n",
407 GNUNET_DISK_pipe_handle (h->helper_out, GNUNET_DISK_PIPE_END_READ);
409 GNUNET_DISK_pipe_handle (h->helper_in, GNUNET_DISK_PIPE_END_WRITE);
411 GNUNET_OS_start_process_vap (h->with_control_pipe, GNUNET_OS_INHERIT_STD_ERR,
412 h->helper_in, h->helper_out,
415 if (NULL == h->helper_proc)
417 /* failed to start process? try again later... */
418 stop_helper (h, GNUNET_NO);
420 GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_UNIT_SECONDS,
424 GNUNET_DISK_pipe_close_end (h->helper_out, GNUNET_DISK_PIPE_END_WRITE);
425 GNUNET_DISK_pipe_close_end (h->helper_in, GNUNET_DISK_PIPE_END_READ);
426 h->read_task = GNUNET_SCHEDULER_add_read_file (GNUNET_TIME_UNIT_FOREVER_REL,
434 * Restart the helper process.
436 * @param cls handle to the helper process
437 * @param tc scheduler context
440 restart_task (void *cls,
441 const struct GNUNET_SCHEDULER_TaskContext *tc)
443 struct GNUNET_HELPER_Handle*h = cls;
445 h->restart_task = GNUNET_SCHEDULER_NO_TASK;
451 * Starts a helper and begins reading from it. The helper process is
452 * restarted when it dies except when it is stopped using GNUNET_HELPER_stop()
453 * or when the exp_cb callback is not NULL.
455 * @param with_control_pipe does the helper support the use of a control pipe for signalling?
456 * @param binary_name name of the binary to run
457 * @param binary_argv NULL-terminated list of arguments to give when starting the binary (this
458 * argument must not be modified by the client for
459 * the lifetime of the helper handle)
460 * @param cb function to call if we get messages from the helper
461 * @param exp_cb the exception callback to call. Set this to NULL if the helper
462 * process has to be restarted automatically when it dies/crashes
463 * @param cb_cls closure for the above callback
464 * @return the new Handle, NULL on error
466 struct GNUNET_HELPER_Handle *
467 GNUNET_HELPER_start (int with_control_pipe,
468 const char *binary_name,
469 char *const binary_argv[],
470 GNUNET_SERVER_MessageTokenizerCallback cb,
471 GNUNET_HELPER_ExceptionCallback exp_cb,
474 struct GNUNET_HELPER_Handle *h;
477 h = GNUNET_malloc (sizeof (struct GNUNET_HELPER_Handle));
478 h->with_control_pipe = with_control_pipe;
479 /* Lookup in libexec path only if we are starting gnunet helpers */
480 if (NULL != strstr (binary_name, "gnunet"))
481 h->binary_name = GNUNET_OS_get_libexec_binary_path (binary_name);
483 h->binary_name = strdup (binary_name);
484 for (c = 0; NULL != binary_argv[c]; c++);
485 h->binary_argv = GNUNET_malloc (sizeof (char *) * (c + 1));
486 for (c = 0; NULL != binary_argv[c]; c++)
487 h->binary_argv[c] = GNUNET_strdup (binary_argv[c]);
488 h->binary_argv[c] = NULL;
490 h->mst = GNUNET_SERVER_mst_create (cb, h->cb_cls);
498 * Free's the resources occupied by the helper handle
500 * @param h the helper handle to free
503 GNUNET_HELPER_destroy (struct GNUNET_HELPER_Handle *h)
507 GNUNET_SERVER_mst_destroy (h->mst);
508 GNUNET_free (h->binary_name);
509 for (c = 0; h->binary_argv[c] != NULL; c++)
510 GNUNET_free (h->binary_argv[c]);
511 GNUNET_free (h->binary_argv);
517 * Kills the helper, closes the pipe and frees the handle
519 * @param h handle to helper to stop
520 * @param soft_kill if GNUNET_YES, signals termination by closing the helper's
521 * stdin; GNUNET_NO to signal termination by sending SIGTERM to helper
524 GNUNET_HELPER_stop (struct GNUNET_HELPER_Handle *h, int soft_kill)
527 stop_helper (h, soft_kill);
528 GNUNET_HELPER_destroy (h);
533 * Write to the helper-process
535 * @param cls handle to the helper process
536 * @param tc scheduler context
539 helper_write (void *cls,
540 const struct GNUNET_SCHEDULER_TaskContext *tc)
542 struct GNUNET_HELPER_Handle *h = cls;
543 struct GNUNET_HELPER_SendHandle *sh;
547 h->write_task = GNUNET_SCHEDULER_NO_TASK;
548 if (0 != (tc->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN))
551 h->write_task = GNUNET_SCHEDULER_add_read_file (GNUNET_TIME_UNIT_FOREVER_REL,
552 h->fh_to_helper, &helper_write, h);
555 if (NULL == (sh = h->sh_head))
556 return; /* how did this happen? */
557 buf = (const char*) sh->msg;
558 t = GNUNET_DISK_file_write (h->fh_to_helper, &buf[sh->wpos], ntohs (sh->msg->size) - sh->wpos);
561 /* On write-error, restart the helper */
562 GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
563 _("Error writing to `%s': %s\n"),
566 if (NULL != h->exp_cb)
568 h->exp_cb (h->cb_cls);
569 GNUNET_HELPER_stop (h, GNUNET_NO);
572 stop_helper (h, GNUNET_NO);
573 /* Restart the helper */
575 GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_UNIT_SECONDS,
580 if (sh->wpos == ntohs (sh->msg->size))
582 GNUNET_CONTAINER_DLL_remove (h->sh_head,
585 if (NULL != sh->cont)
586 sh->cont (sh->cont_cls, GNUNET_YES);
589 if (NULL != h->sh_head)
590 h->write_task = GNUNET_SCHEDULER_add_write_file (GNUNET_TIME_UNIT_FOREVER_REL,
598 * Send an message to the helper.
600 * @param h helper to send message to
601 * @param msg message to send
602 * @param can_drop can the message be dropped if there is already one in the queue?
603 * @param cont continuation to run once the message is out (PREREQ_DONE on succees, CANCEL
604 * if the helper process died, NULL during GNUNET_HELPER_stop).
605 * @param cont_cls closure for 'cont'
606 * @return NULL if the message was dropped,
607 * otherwise handle to cancel *cont* (actual transmission may
610 struct GNUNET_HELPER_SendHandle *
611 GNUNET_HELPER_send (struct GNUNET_HELPER_Handle *h,
612 const struct GNUNET_MessageHeader *msg,
614 GNUNET_HELPER_Continuation cont,
617 struct GNUNET_HELPER_SendHandle *sh;
620 if (NULL == h->fh_to_helper)
622 if ( (GNUNET_YES == can_drop) &&
623 (NULL != h->sh_head) )
625 mlen = ntohs (msg->size);
626 sh = GNUNET_malloc (sizeof (struct GNUNET_HELPER_SendHandle) + mlen);
627 sh->msg = (const struct GNUNET_MessageHeader*) &sh[1];
628 memcpy (&sh[1], msg, mlen);
631 sh->cont_cls = cont_cls;
632 GNUNET_CONTAINER_DLL_insert_tail (h->sh_head,
635 if (GNUNET_SCHEDULER_NO_TASK == h->write_task)
636 h->write_task = GNUNET_SCHEDULER_add_write_file (GNUNET_TIME_UNIT_FOREVER_REL,
645 * Cancel a 'send' operation. If possible, transmitting the
646 * message is also aborted, but at least 'cont' won't be
649 * @param sh operation to cancel
652 GNUNET_HELPER_send_cancel (struct GNUNET_HELPER_SendHandle *sh)
654 struct GNUNET_HELPER_Handle *h = sh->h;
660 GNUNET_CONTAINER_DLL_remove (h->sh_head, h->sh_tail, sh);
661 if (NULL == h->sh_head)
663 GNUNET_SCHEDULER_cancel (h->write_task);
664 h->write_task = GNUNET_SCHEDULER_NO_TASK;
671 /* end of helper.c */