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 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.
18 * @brief API for dealing with (SUID) helper processes that communicate via
19 * GNUNET_MessageHeaders on stdin/stdout
20 * @author Philipp Toelke
21 * @author Christian Grothoff
24 #include "gnunet_util_lib.h"
25 #include "gnunet_mst_lib.h"
29 * Entry in the queue of messages we need to transmit to the helper.
31 struct GNUNET_HELPER_SendHandle
35 * This is an entry in a DLL.
37 struct GNUNET_HELPER_SendHandle *next;
40 * This is an entry in a DLL.
42 struct GNUNET_HELPER_SendHandle *prev;
45 * Message to transmit (allocated at the end of this struct)
47 const struct GNUNET_MessageHeader *msg;
50 * The handle to a helper process.
52 struct GNUNET_HELPER_Handle *h;
55 * Function to call upon completion.
57 GNUNET_HELPER_Continuation cont;
65 * Current write position.
73 * The handle to a helper process.
75 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,
178 struct GNUNET_HELPER_SendHandle *sh;
181 while (NULL != (sh = h->sh_head))
183 GNUNET_CONTAINER_DLL_remove (h->sh_head,
186 if (NULL != sh->cont)
187 sh->cont (sh->cont_cls, GNUNET_NO);
190 if (NULL != h->restart_task)
192 GNUNET_SCHEDULER_cancel (h->restart_task);
193 h->restart_task = NULL;
195 if (NULL != h->read_task)
197 GNUNET_SCHEDULER_cancel (h->read_task);
200 if (NULL == h->helper_proc)
201 return GNUNET_SYSERR;
202 if (GNUNET_YES == soft_kill)
204 /* soft-kill only possible with pipes */
205 GNUNET_assert (NULL != h->helper_in);
206 ret = GNUNET_DISK_pipe_close (h->helper_in);
208 h->fh_to_helper = NULL;
211 if (0 != GNUNET_OS_process_kill (h->helper_proc, GNUNET_TERM_SIG))
212 return GNUNET_SYSERR;
218 * Reap the helper process. This call is blocking(!). The helper process
219 * should either be sent a termination signal before or should be dead before
220 * calling this function
222 * @param h the helper handle
223 * @return #GNUNET_OK on success; #GNUNET_SYSERR on error
226 GNUNET_HELPER_wait (struct GNUNET_HELPER_Handle *h)
228 struct GNUNET_HELPER_SendHandle *sh;
232 if (NULL != h->helper_proc)
234 ret = GNUNET_OS_process_wait (h->helper_proc);
235 GNUNET_OS_process_destroy (h->helper_proc);
236 h->helper_proc = NULL;
238 if (NULL != h->read_task)
240 GNUNET_SCHEDULER_cancel (h->read_task);
243 if (NULL != h->write_task)
245 GNUNET_SCHEDULER_cancel (h->write_task);
246 h->write_task = NULL;
248 if (NULL != h->helper_in)
250 GNUNET_DISK_pipe_close (h->helper_in);
252 h->fh_to_helper = NULL;
254 if (NULL != h->helper_out)
256 GNUNET_DISK_pipe_close (h->helper_out);
257 h->helper_out = NULL;
258 h->fh_from_helper = NULL;
260 while (NULL != (sh = h->sh_head))
262 GNUNET_CONTAINER_DLL_remove (h->sh_head,
265 if (NULL != sh->cont)
266 sh->cont (sh->cont_cls, GNUNET_NO);
269 /* purge MST buffer */
271 (void) GNUNET_MST_from_buffer (h->mst,
280 * Stop the helper process, we're closing down or had an error.
282 * @param h handle to the helper process
283 * @param soft_kill if #GNUNET_YES, signals termination by closing the helper's
284 * stdin; #GNUNET_NO to signal termination by sending SIGTERM to helper
287 stop_helper (struct GNUNET_HELPER_Handle *h,
290 if (NULL != h->restart_task)
292 GNUNET_SCHEDULER_cancel (h->restart_task);
293 h->restart_task = NULL;
297 GNUNET_break (GNUNET_OK == GNUNET_HELPER_kill (h, soft_kill));
298 GNUNET_break (GNUNET_OK == GNUNET_HELPER_wait (h));
304 * Restart the helper process.
306 * @param cls handle to the helper process
309 restart_task (void *cls);
313 * Read from the helper-process
315 * @param cls handle to the helper process
318 helper_read (void *cls)
320 struct GNUNET_HELPER_Handle *h = cls;
321 char buf[GNUNET_MAX_MESSAGE_SIZE] GNUNET_ALIGN;
325 t = GNUNET_DISK_file_read (h->fh_from_helper, &buf, sizeof (buf));
328 /* On read-error, restart the helper */
329 GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
330 _("Error reading from `%s': %s\n"),
333 if (NULL != h->exp_cb)
335 h->exp_cb (h->cb_cls);
336 GNUNET_HELPER_stop (h, GNUNET_NO);
339 stop_helper (h, GNUNET_NO);
340 /* Restart the helper */
341 h->restart_task = GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS,
348 /* this happens if the helper is shut down via a
349 signal, so it is not a "hard" error */
350 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
351 "Got 0 bytes from helper `%s' (EOF)\n",
353 if (NULL != h->exp_cb)
355 h->exp_cb (h->cb_cls);
356 GNUNET_HELPER_stop (h, GNUNET_NO);
359 stop_helper (h, GNUNET_NO);
360 /* Restart the helper */
362 = GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS,
367 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
368 "Got %u bytes from helper `%s'\n",
371 h->read_task = GNUNET_SCHEDULER_add_read_file (GNUNET_TIME_UNIT_FOREVER_REL,
375 GNUNET_MST_from_buffer (h->mst,
380 GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
381 _("Failed to parse inbound message from helper `%s'\n"),
383 if (NULL != h->exp_cb)
385 h->exp_cb (h->cb_cls);
386 GNUNET_HELPER_stop (h, GNUNET_NO);
389 stop_helper (h, GNUNET_NO);
390 /* Restart the helper */
391 h->restart_task = GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_relative_multiply(GNUNET_TIME_UNIT_SECONDS,
400 * Start the helper process.
402 * @param h handle to the helper process
405 start_helper (struct GNUNET_HELPER_Handle *h)
407 h->helper_in = GNUNET_DISK_pipe (GNUNET_YES, GNUNET_YES, GNUNET_YES, GNUNET_NO);
408 h->helper_out = GNUNET_DISK_pipe (GNUNET_YES, GNUNET_YES, GNUNET_NO, GNUNET_YES);
409 if ( (h->helper_in == NULL) || (h->helper_out == NULL))
411 /* out of file descriptors? try again later... */
412 stop_helper (h, GNUNET_NO);
414 GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_relative_multiply(GNUNET_TIME_UNIT_SECONDS,
419 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
420 "Starting HELPER process `%s'\n",
423 GNUNET_DISK_pipe_handle (h->helper_out, GNUNET_DISK_PIPE_END_READ);
425 GNUNET_DISK_pipe_handle (h->helper_in, GNUNET_DISK_PIPE_END_WRITE);
427 GNUNET_OS_start_process_vap (h->with_control_pipe, GNUNET_OS_INHERIT_STD_ERR,
428 h->helper_in, h->helper_out, NULL,
431 if (NULL == h->helper_proc)
433 /* failed to start process? try again later... */
434 stop_helper (h, GNUNET_NO);
435 h->restart_task = GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_relative_multiply(GNUNET_TIME_UNIT_SECONDS,
440 GNUNET_DISK_pipe_close_end (h->helper_out, GNUNET_DISK_PIPE_END_WRITE);
441 GNUNET_DISK_pipe_close_end (h->helper_in, GNUNET_DISK_PIPE_END_READ);
443 h->read_task = GNUNET_SCHEDULER_add_read_file (GNUNET_TIME_UNIT_FOREVER_REL,
451 * Restart the helper process.
453 * @param cls handle to the helper process
456 restart_task (void *cls)
458 struct GNUNET_HELPER_Handle*h = cls;
460 h->restart_task = NULL;
462 GNUNET_log (GNUNET_ERROR_TYPE_INFO,
463 "Restarting helper with back-off %u\n",
470 * Starts a helper and begins reading from it. The helper process is
471 * restarted when it dies except when it is stopped using GNUNET_HELPER_stop()
472 * or when the exp_cb callback is not NULL.
474 * @param with_control_pipe does the helper support the use of a control pipe for signalling?
475 * @param binary_name name of the binary to run
476 * @param binary_argv NULL-terminated list of arguments to give when starting the binary (this
477 * argument must not be modified by the client for
478 * the lifetime of the helper handle)
479 * @param cb function to call if we get messages from the helper
480 * @param exp_cb the exception callback to call. Set this to NULL if the helper
481 * process has to be restarted automatically when it dies/crashes
482 * @param cb_cls closure for the above callback
483 * @return the new Handle, NULL on error
485 struct GNUNET_HELPER_Handle *
486 GNUNET_HELPER_start (int with_control_pipe,
487 const char *binary_name,
488 char *const binary_argv[],
489 GNUNET_MessageTokenizerCallback cb,
490 GNUNET_HELPER_ExceptionCallback exp_cb,
493 struct GNUNET_HELPER_Handle *h;
496 h = GNUNET_new (struct GNUNET_HELPER_Handle);
497 h->with_control_pipe = with_control_pipe;
498 /* Lookup in libexec path only if we are starting gnunet helpers */
499 if (NULL != strstr (binary_name, "gnunet"))
500 h->binary_name = GNUNET_OS_get_libexec_binary_path (binary_name);
502 h->binary_name = GNUNET_strdup (binary_name);
503 for (c = 0; NULL != binary_argv[c]; c++);
504 h->binary_argv = GNUNET_malloc (sizeof (char *) * (c + 1));
505 for (c = 0; NULL != binary_argv[c]; c++)
506 h->binary_argv[c] = GNUNET_strdup (binary_argv[c]);
507 h->binary_argv[c] = NULL;
510 h->mst = GNUNET_MST_create (cb,
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_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 GNUNET_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 */