2 This file is part of GNUnet
3 (C) 2009, 2011 Christian Grothoff (and other contributing authors)
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6 it under the terms of the GNU General Public License as published
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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.
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21 * @file src/fragmentation/fragmentation.c
22 * @brief library to help fragment messages
23 * @author Christian Grothoff
26 #include "gnunet_fragmentation_lib.h"
27 #include "gnunet_protocols.h"
28 #include "fragmentation.h"
32 * Fragmentation context.
34 struct GNUNET_FRAGMENT_Context
39 struct GNUNET_STATISTICS_Handle *stats;
42 * Tracker for flow control.
44 struct GNUNET_BANDWIDTH_Tracker *tracker;
47 * Current expected delay for ACKs.
49 struct GNUNET_TIME_Relative delay;
52 * Next allowed transmission time.
54 struct GNUNET_TIME_Absolute delay_until;
57 * Time we transmitted the last message of the last round.
59 struct GNUNET_TIME_Absolute last_round;
62 * Message to fragment (allocated at the end of this struct).
64 const struct GNUNET_MessageHeader *msg;
67 * Function to call for transmissions.
69 GNUNET_FRAGMENT_MessageProcessor proc;
77 * Bitfield, set to 1 for each unacknowledged fragment.
82 * Bitfield with all possible bits for 'acks' (used to mask the
88 * Task performing work for the fragmenter.
90 GNUNET_SCHEDULER_TaskIdentifier task;
93 * Our fragmentation ID. (chosen at random)
98 * Round-robin selector for the next transmission.
100 unsigned int next_transmission;
103 * How many rounds of transmission have we completed so far?
105 unsigned int num_rounds;
108 * GNUNET_YES if we called 'proc' and are now waiting for 'GNUNET_FRAGMENT_transmission_done'
113 * GNUNET_YES if we are waiting for an ACK.
118 * Target fragment size.
126 * Transmit the next fragment to the other peer.
128 * @param cls the 'struct GNUNET_FRAGMENT_Context'
129 * @param tc scheduler context
132 transmit_next (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
134 struct GNUNET_FRAGMENT_Context *fc = cls;
137 struct FragmentHeader *fh;
138 struct GNUNET_TIME_Relative delay;
144 fc->task = GNUNET_SCHEDULER_NO_TASK;
145 GNUNET_assert (GNUNET_NO == fc->proc_busy);
147 return; /* all done */
149 /* calculate delay */
151 while (0 == (fc->acks & (1LL << fc->next_transmission)))
153 fc->next_transmission = (fc->next_transmission + 1) % 64;
154 wrap |= (fc->next_transmission == 0);
156 bit = fc->next_transmission;
157 size = ntohs (fc->msg->size);
158 if (bit == size / (fc->mtu - sizeof (struct FragmentHeader)))
160 (size % (fc->mtu - sizeof (struct FragmentHeader))) +
161 sizeof (struct FragmentHeader);
164 if (fc->tracker != NULL)
165 delay = GNUNET_BANDWIDTH_tracker_get_delay (fc->tracker, fsize);
167 delay = GNUNET_TIME_UNIT_ZERO;
168 if (delay.rel_value > 0)
170 fc->task = GNUNET_SCHEDULER_add_delayed (delay, &transmit_next, fc);
173 fc->next_transmission = (fc->next_transmission + 1) % 64;
174 wrap |= (fc->next_transmission == 0);
176 /* assemble fragmentation message */
177 mbuf = (const char *) &fc[1];
178 fh = (struct FragmentHeader *) msg;
179 fh->header.size = htons (fsize);
180 fh->header.type = htons (GNUNET_MESSAGE_TYPE_FRAGMENT);
181 fh->fragment_id = htonl (fc->fragment_id);
182 fh->total_size = fc->msg->size; /* already in big-endian */
183 fh->offset = htons ((fc->mtu - sizeof (struct FragmentHeader)) * bit);
184 memcpy (&fh[1], &mbuf[bit * (fc->mtu - sizeof (struct FragmentHeader))],
185 fsize - sizeof (struct FragmentHeader));
186 if (NULL != fc->tracker)
187 GNUNET_BANDWIDTH_tracker_consume (fc->tracker, fsize);
188 GNUNET_STATISTICS_update (fc->stats, _("# fragments transmitted"), 1,
190 if (0 != fc->last_round.abs_value)
191 GNUNET_STATISTICS_update (fc->stats, _("# fragments retransmitted"), 1,
194 /* select next message to calculate delay */
195 bit = fc->next_transmission;
196 size = ntohs (fc->msg->size);
197 if (bit == size / (fc->mtu - sizeof (struct FragmentHeader)))
198 fsize = size % (fc->mtu - sizeof (struct FragmentHeader));
201 if (NULL != fc->tracker)
202 delay = GNUNET_BANDWIDTH_tracker_get_delay (fc->tracker, fsize);
204 delay = GNUNET_TIME_UNIT_ZERO;
207 /* full round transmitted wait 2x delay for ACK before going again */
210 GNUNET_TIME_relative_max (GNUNET_TIME_relative_multiply (delay, 2),
211 GNUNET_TIME_relative_multiply (fc->delay, fc->num_rounds));
212 /* never use zero, need some time for ACK always */
213 delay = GNUNET_TIME_relative_max (GNUNET_TIME_UNIT_MILLISECONDS, delay);
214 fc->last_round = GNUNET_TIME_absolute_get ();
215 fc->wack = GNUNET_YES;
217 fc->proc_busy = GNUNET_YES;
218 fc->delay_until = GNUNET_TIME_relative_to_absolute (delay);
219 fc->proc (fc->proc_cls, &fh->header);
224 * Create a fragmentation context for the given message.
225 * Fragments the message into fragments of size "mtu" or
226 * less. Calls 'proc' on each un-acknowledged fragment,
227 * using both the expected 'delay' between messages and
228 * acknowledgements and the given 'tracker' to guide the
229 * frequency of calls to 'proc'.
231 * @param stats statistics context
232 * @param mtu the maximum message size for each fragment
233 * @param tracker bandwidth tracker to use for flow control (can be NULL)
234 * @param delay expected delay between fragment transmission
235 * and ACK based on previous messages
236 * @param msg the message to fragment
237 * @param proc function to call for each fragment to transmit
238 * @param proc_cls closure for proc
239 * @return the fragmentation context
241 struct GNUNET_FRAGMENT_Context *
242 GNUNET_FRAGMENT_context_create (struct GNUNET_STATISTICS_Handle *stats,
244 struct GNUNET_BANDWIDTH_Tracker *tracker,
245 struct GNUNET_TIME_Relative delay,
246 const struct GNUNET_MessageHeader *msg,
247 GNUNET_FRAGMENT_MessageProcessor proc,
250 struct GNUNET_FRAGMENT_Context *fc;
254 GNUNET_STATISTICS_update (stats, _("# messages fragmented"), 1, GNUNET_NO);
255 GNUNET_assert (mtu >= 1024 + sizeof (struct FragmentHeader));
256 size = ntohs (msg->size);
257 GNUNET_STATISTICS_update (stats, _("# total size of fragmented messages"),
259 GNUNET_assert (size >= sizeof (struct GNUNET_MessageHeader));
260 fc = GNUNET_malloc (sizeof (struct GNUNET_FRAGMENT_Context) + size);
263 fc->tracker = tracker;
265 fc->msg = (const struct GNUNET_MessageHeader *) &fc[1];
267 fc->proc_cls = proc_cls;
269 GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_WEAK, UINT32_MAX);
270 memcpy (&fc[1], msg, size);
272 (size + mtu - sizeof (struct FragmentHeader) - 1) / (mtu -
275 GNUNET_assert (bits <= 64);
277 fc->acks_mask = UINT64_MAX; /* set all 64 bit */
279 fc->acks_mask = (1LL << bits) - 1; /* set lowest 'bits' bit */
280 fc->acks = fc->acks_mask;
281 fc->task = GNUNET_SCHEDULER_add_now (&transmit_next, fc);
287 * Continuation to call from the 'proc' function after the fragment
288 * has been transmitted (and hence the next fragment can now be
291 * @param fc fragmentation context
294 GNUNET_FRAGMENT_context_transmission_done (struct GNUNET_FRAGMENT_Context *fc)
296 GNUNET_assert (fc->proc_busy == GNUNET_YES);
297 fc->proc_busy = GNUNET_NO;
298 GNUNET_assert (fc->task == GNUNET_SCHEDULER_NO_TASK);
300 GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_absolute_get_remaining
301 (fc->delay_until), &transmit_next, fc);
306 * Process an acknowledgement message we got from the other
307 * side (to control re-transmits).
309 * @param fc fragmentation context
310 * @param msg acknowledgement message we received
311 * @return GNUNET_OK if this ack completes the work of the 'fc'
312 * (all fragments have been received);
313 * GNUNET_NO if more messages are pending
314 * GNUNET_SYSERR if this ack is not valid for this fc
317 GNUNET_FRAGMENT_process_ack (struct GNUNET_FRAGMENT_Context *fc,
318 const struct GNUNET_MessageHeader *msg)
320 const struct FragmentAcknowledgement *fa;
322 struct GNUNET_TIME_Relative ndelay;
324 if (sizeof (struct FragmentAcknowledgement) != ntohs (msg->size))
327 return GNUNET_SYSERR;
329 fa = (const struct FragmentAcknowledgement *) msg;
330 if (ntohl (fa->fragment_id) != fc->fragment_id)
331 return GNUNET_SYSERR; /* not our ACK */
332 abits = GNUNET_ntohll (fa->bits);
333 if ( (GNUNET_YES == fc->wack) &&
334 (abits == (fc->acks & abits)) )
336 /* normal ACK, can update running average of delay... */
337 fc->wack = GNUNET_NO;
338 ndelay = GNUNET_TIME_absolute_get_duration (fc->last_round);
339 fc->delay.rel_value = (ndelay.rel_value * fc->num_rounds + 3 * fc->delay.rel_value) / 4;
341 GNUNET_STATISTICS_update (fc->stats,
342 _("# fragment acknowledgements received"), 1,
344 if (abits != (fc->acks & abits))
346 /* ID collission or message reordering, count! This should be rare! */
347 GNUNET_STATISTICS_update (fc->stats,
348 _("# bits removed from fragmentation ACKs"), 1,
351 fc->acks = abits & fc->acks_mask;
354 /* more to transmit, do so right now (if tracker permits...) */
355 if (fc->task != GNUNET_SCHEDULER_NO_TASK)
357 /* schedule next transmission now, no point in waiting... */
358 GNUNET_SCHEDULER_cancel (fc->task);
359 fc->task = GNUNET_SCHEDULER_add_now (&transmit_next, fc);
363 /* only case where there is no task should be if we're waiting
364 * for the right to transmit again (proc_busy set to YES) */
365 GNUNET_assert (GNUNET_YES == fc->proc_busy);
371 GNUNET_STATISTICS_update (fc->stats,
372 _("# fragmentation transmissions completed"), 1,
374 if (fc->task != GNUNET_SCHEDULER_NO_TASK)
376 GNUNET_SCHEDULER_cancel (fc->task);
377 fc->task = GNUNET_SCHEDULER_NO_TASK;
384 * Destroy the given fragmentation context (stop calling 'proc', free
387 * @param fc fragmentation context
388 * @return average delay between transmission and ACK for the
389 * last message, FOREVER if the message was not fully transmitted
391 struct GNUNET_TIME_Relative
392 GNUNET_FRAGMENT_context_destroy (struct GNUNET_FRAGMENT_Context *fc)
394 struct GNUNET_TIME_Relative ret;
396 if (fc->task != GNUNET_SCHEDULER_NO_TASK)
397 GNUNET_SCHEDULER_cancel (fc->task);
404 /* end of fragmentation.c */