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3 (C) 2011, 2012 Christian Grothoff
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23 * @brief API for dealing with (SUID) helper processes that communicate via GNUNET_MessageHeaders on stdin/stdout
24 * @author Philipp Toelke
25 * @author Christian Grothoff
28 #include "gnunet_util_lib.h"
32 * Entry in the queue of messages we need to transmit to the helper.
34 struct HelperMessageQueueEntry
38 * This is an entry in a DLL.
40 struct HelperMessageQueueEntry *next;
43 * This is an entry in a DLL.
45 struct HelperMessageQueueEntry *prev;
48 * Message to transmit (allocated at the end of this struct)
50 const struct GNUNET_MessageHeader *msg;
53 * Function to call upon completion.
55 GNUNET_HELPER_Continuation cont;
63 * Current write position.
71 * The handle to a helper process.
73 struct GNUNET_HELPER_Handle
77 * PipeHandle to receive data from the helper
79 struct GNUNET_DISK_PipeHandle *helper_in;
82 * PipeHandle to send data to the helper
84 struct GNUNET_DISK_PipeHandle *helper_out;
87 * FileHandle to receive data from the helper
89 const struct GNUNET_DISK_FileHandle *fh_from_helper;
92 * FileHandle to send data to the helper
94 const struct GNUNET_DISK_FileHandle *fh_to_helper;
97 * The process id of the helper
99 struct GNUNET_OS_Process *helper_proc;
102 * The Message-Tokenizer that tokenizes the messages comming from the helper
104 struct GNUNET_SERVER_MessageStreamTokenizer *mst;
107 * First message queued for transmission to helper.
109 struct HelperMessageQueueEntry *mq_head;
112 * Last message queued for transmission to helper.
114 struct HelperMessageQueueEntry *mq_tail;
119 const char *binary_name;
122 * NULL-terminated list of command-line arguments.
124 char *const *binary_argv;
127 * Task to read from the helper.
129 GNUNET_SCHEDULER_TaskIdentifier read_task;
132 * Task to read from the helper.
134 GNUNET_SCHEDULER_TaskIdentifier write_task;
139 GNUNET_SCHEDULER_TaskIdentifier restart_task;
144 * Stop the helper process, we're closing down or had an error.
146 * @param h handle to the helper process
149 stop_helper (struct GNUNET_HELPER_Handle *h)
151 struct HelperMessageQueueEntry *qe;
153 if (NULL != h->helper_proc)
155 GNUNET_break (0 == GNUNET_OS_process_kill (h->helper_proc, SIGTERM));
156 GNUNET_break (GNUNET_OK == GNUNET_OS_process_wait (h->helper_proc));
157 GNUNET_OS_process_close (h->helper_proc);
158 h->helper_proc = NULL;
160 if (GNUNET_SCHEDULER_NO_TASK != h->restart_task)
162 GNUNET_SCHEDULER_cancel (h->restart_task);
163 h->restart_task = GNUNET_SCHEDULER_NO_TASK;
165 if (GNUNET_SCHEDULER_NO_TASK != h->read_task)
167 GNUNET_SCHEDULER_cancel (h->read_task);
168 h->read_task = GNUNET_SCHEDULER_NO_TASK;
170 if (GNUNET_SCHEDULER_NO_TASK != h->write_task)
172 GNUNET_SCHEDULER_cancel (h->write_task);
173 h->write_task = GNUNET_SCHEDULER_NO_TASK;
175 if (NULL != h->helper_in)
177 GNUNET_DISK_pipe_close (h->helper_in);
179 h->fh_to_helper = NULL;
181 if (NULL != h->helper_out)
183 GNUNET_DISK_pipe_close (h->helper_out);
184 h->helper_out = NULL;
185 h->fh_from_helper = NULL;
187 while (NULL != (qe = h->mq_head))
189 GNUNET_CONTAINER_DLL_remove (h->mq_head,
192 if (NULL != qe->cont)
193 qe->cont (qe->cont_cls, GNUNET_NO);
196 /* purge MST buffer */
197 GNUNET_SERVER_mst_receive (h->mst, NULL, NULL, 0, GNUNET_YES, GNUNET_NO);
202 * Restart the helper process.
204 * @param cls handle to the helper process
205 * @param tc scheduler context
208 restart_task (void *cls,
209 const struct GNUNET_SCHEDULER_TaskContext *tc);
213 * Read from the helper-process
215 * @param cls handle to the helper process
216 * @param tc scheduler context
219 helper_read (void *cls,
220 const struct GNUNET_SCHEDULER_TaskContext *tc)
222 struct GNUNET_HELPER_Handle *h = cls;
223 char buf[GNUNET_SERVER_MAX_MESSAGE_SIZE];
226 h->read_task = GNUNET_SCHEDULER_NO_TASK;
227 if (0 != (tc->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN))
230 h->read_task = GNUNET_SCHEDULER_add_read_file (GNUNET_TIME_UNIT_FOREVER_REL,
231 h->fh_from_helper, &helper_read, h);
234 t = GNUNET_DISK_file_read (h->fh_from_helper, &buf, sizeof (buf));
237 /* On read-error, restart the helper */
238 GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
239 _("Error reading from `%s': %s\n"),
243 /* Restart the helper */
245 GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_UNIT_SECONDS,
251 /* this happens if the helper is shut down via a
252 signal, so it is not a "hard" error */
253 GNUNET_log (GNUNET_ERROR_TYPE_INFO,
254 _("Got 0 bytes from helper `%s' (EOF)\n"),
257 /* Restart the helper */
259 GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_UNIT_SECONDS,
263 GNUNET_log (GNUNET_ERROR_TYPE_INFO,
264 _("Got %u bytes from helper `%s'\n"),
268 GNUNET_SERVER_mst_receive (h->mst, NULL, buf, t, GNUNET_NO, GNUNET_NO))
270 GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
271 _("Failed to parse inbound message from helper `%s'\n"),
274 /* Restart the helper */
276 GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_UNIT_SECONDS,
281 h->read_task = GNUNET_SCHEDULER_add_read_file (GNUNET_TIME_UNIT_FOREVER_REL,
282 h->fh_from_helper, &helper_read, h);
287 * Start the helper process.
289 * @param h handle to the helper process
292 start_helper (struct GNUNET_HELPER_Handle *h)
294 h->helper_in = GNUNET_DISK_pipe (GNUNET_YES, GNUNET_YES, GNUNET_YES, GNUNET_NO);
295 h->helper_out = GNUNET_DISK_pipe (GNUNET_YES, GNUNET_YES, GNUNET_NO, GNUNET_YES);
296 if ( (h->helper_in == NULL) || (h->helper_out == NULL))
298 /* out of file descriptors? try again later... */
301 GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_UNIT_SECONDS,
306 GNUNET_DISK_pipe_handle (h->helper_out, GNUNET_DISK_PIPE_END_READ);
308 GNUNET_DISK_pipe_handle (h->helper_in, GNUNET_DISK_PIPE_END_WRITE);
310 GNUNET_OS_start_process_vap (h->helper_in, h->helper_out,
313 if (NULL == h->helper_proc)
315 /* failed to start process? try again later... */
318 GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_UNIT_SECONDS,
322 GNUNET_DISK_pipe_close_end (h->helper_out, GNUNET_DISK_PIPE_END_WRITE);
323 GNUNET_DISK_pipe_close_end (h->helper_in, GNUNET_DISK_PIPE_END_READ);
324 h->read_task = GNUNET_SCHEDULER_add_read_file (GNUNET_TIME_UNIT_FOREVER_REL,
332 * Restart the helper process.
334 * @param cls handle to the helper process
335 * @param tc scheduler context
338 restart_task (void *cls,
339 const struct GNUNET_SCHEDULER_TaskContext *tc)
341 struct GNUNET_HELPER_Handle*h = cls;
343 h->restart_task = GNUNET_SCHEDULER_NO_TASK;
349 * @brief Starts a helper and begins reading from it
351 * @param binary_name name of the binary to run
352 * @param binary_argv NULL-terminated list of arguments to give when starting the binary (this
353 * argument must not be modified by the client for
354 * the lifetime of the helper h)
355 * @param cb function to call if we get messages from the helper
356 * @param cb_cls Closure for the callback
357 * @return the new H, NULL on error
359 struct GNUNET_HELPER_Handle*
360 GNUNET_HELPER_start (const char *binary_name,
361 char *const binary_argv[],
362 GNUNET_SERVER_MessageTokenizerCallback cb, void *cb_cls)
364 struct GNUNET_HELPER_Handle*h;
366 h = GNUNET_malloc (sizeof (struct GNUNET_HELPER_Handle));
367 h->binary_name = binary_name;
368 h->binary_argv = binary_argv;
369 h->mst = GNUNET_SERVER_mst_create (cb, cb_cls);
376 * @brief Kills the helper, closes the pipe and frees the h
378 * @param h h to helper to stop
381 GNUNET_HELPER_stop (struct GNUNET_HELPER_Handle *h)
383 struct HelperMessageQueueEntry *qe;
385 /* signal pending writes that we were stopped */
386 while (NULL != (qe = h->mq_head))
388 GNUNET_CONTAINER_DLL_remove (h->mq_head,
391 if (NULL != qe->cont)
392 qe->cont (qe->cont_cls, GNUNET_SYSERR);
396 GNUNET_SERVER_mst_destroy (h->mst);
402 * Write to the helper-process
404 * @param cls handle to the helper process
405 * @param tc scheduler context
408 helper_write (void *cls,
409 const struct GNUNET_SCHEDULER_TaskContext *tc)
411 struct GNUNET_HELPER_Handle *h = cls;
412 struct HelperMessageQueueEntry *qe;
416 h->write_task = GNUNET_SCHEDULER_NO_TASK;
417 if (0 != (tc->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN))
420 h->write_task = GNUNET_SCHEDULER_add_read_file (GNUNET_TIME_UNIT_FOREVER_REL,
421 h->fh_to_helper, &helper_write, h);
424 if (NULL == (qe = h->mq_head))
425 return; /* how did this happen? */
426 buf = (const char*) qe->msg;
427 t = GNUNET_DISK_file_write (h->fh_to_helper, &buf[qe->wpos], ntohs (qe->msg->size) - qe->wpos);
430 /* On write-error, restart the helper */
431 GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
432 _("Error writing to `%s': %s\n"),
436 /* Restart the helper */
438 GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_UNIT_SECONDS,
443 if (qe->wpos == ntohs (qe->msg->size))
445 GNUNET_CONTAINER_DLL_remove (h->mq_head,
448 if (NULL != qe->cont)
449 qe->cont (qe->cont_cls, GNUNET_YES);
452 if (NULL != h->mq_head)
453 h->write_task = GNUNET_SCHEDULER_add_write_file (GNUNET_TIME_UNIT_FOREVER_REL,
461 * Send an message to the helper.
463 * @param h helper to send message to
464 * @param msg message to send
465 * @param can_drop can the message be dropped if there is already one in the queue?
466 * @param cont continuation to run once the message is out (PREREQ_DONE on succees, CANCEL
467 * if the helper process died, NULL during GNUNET_HELPER_stop).
468 * @param cont_cls closure for 'cont'
469 * @return GNUNET_YES if the message will be sent
470 * GNUNET_NO if the message was dropped
473 GNUNET_HELPER_send (struct GNUNET_HELPER_Handle *h,
474 const struct GNUNET_MessageHeader *msg,
476 GNUNET_HELPER_Continuation cont,
479 struct HelperMessageQueueEntry *qe;
482 if (NULL == h->fh_to_helper)
484 if ( (GNUNET_YES == can_drop) &&
485 (h->mq_head != NULL) )
487 mlen = ntohs (msg->size);
488 qe = GNUNET_malloc (sizeof (struct HelperMessageQueueEntry) + mlen);
489 qe->msg = (const struct GNUNET_MessageHeader*) &qe[1];
490 memcpy (&qe[1], msg, mlen);
492 qe->cont_cls = cont_cls;
493 GNUNET_CONTAINER_DLL_insert_tail (h->mq_head,
496 if (GNUNET_SCHEDULER_NO_TASK == h->write_task)
497 h->write_task = GNUNET_SCHEDULER_add_write_file (GNUNET_TIME_UNIT_FOREVER_REL,
506 /* end of helper.c */