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 * GNUNET_YES if we called 'proc' and are now waiting for 'GNUNET_FRAGMENT_transmission_done'
108 * GNUNET_YES if we are waiting for an ACK.
113 * Target fragment size.
121 * Transmit the next fragment to the other peer.
123 * @param cls the 'struct GNUNET_FRAGMENT_Context'
124 * @param tc scheduler context
127 transmit_next (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
129 struct GNUNET_FRAGMENT_Context *fc = cls;
132 struct FragmentHeader *fh;
133 struct GNUNET_TIME_Relative delay;
139 fc->task = GNUNET_SCHEDULER_NO_TASK;
140 GNUNET_assert (GNUNET_NO == fc->proc_busy);
142 return; /* all done */
144 /* calculate delay */
146 while (0 == (fc->acks & (1LL << fc->next_transmission)))
148 fc->next_transmission = (fc->next_transmission + 1) % 64;
149 wrap |= (fc->next_transmission == 0);
151 bit = fc->next_transmission;
152 size = ntohs (fc->msg->size);
153 if (bit == size / (fc->mtu - sizeof (struct FragmentHeader)))
155 (size % (fc->mtu - sizeof (struct FragmentHeader))) +
156 sizeof (struct FragmentHeader);
159 if (fc->tracker != NULL)
160 delay = GNUNET_BANDWIDTH_tracker_get_delay (fc->tracker, fsize);
162 delay = GNUNET_TIME_UNIT_ZERO;
163 if (delay.rel_value > 0)
165 fc->task = GNUNET_SCHEDULER_add_delayed (delay, &transmit_next, fc);
168 fc->next_transmission = (fc->next_transmission + 1) % 64;
169 wrap |= (fc->next_transmission == 0);
171 /* assemble fragmentation message */
172 mbuf = (const char *) &fc[1];
173 fh = (struct FragmentHeader *) msg;
174 fh->header.size = htons (fsize);
175 fh->header.type = htons (GNUNET_MESSAGE_TYPE_FRAGMENT);
176 fh->fragment_id = htonl (fc->fragment_id);
177 fh->total_size = fc->msg->size; /* already in big-endian */
178 fh->offset = htons ((fc->mtu - sizeof (struct FragmentHeader)) * bit);
179 memcpy (&fh[1], &mbuf[bit * (fc->mtu - sizeof (struct FragmentHeader))],
180 fsize - sizeof (struct FragmentHeader));
181 if (NULL != fc->tracker)
182 GNUNET_BANDWIDTH_tracker_consume (fc->tracker, fsize);
183 GNUNET_STATISTICS_update (fc->stats, _("# fragments transmitted"), 1,
185 if (0 != fc->last_round.abs_value)
186 GNUNET_STATISTICS_update (fc->stats, _("# fragments retransmitted"), 1,
189 /* select next message to calculate delay */
190 bit = fc->next_transmission;
191 size = ntohs (fc->msg->size);
192 if (bit == size / (fc->mtu - sizeof (struct FragmentHeader)))
193 fsize = size % (fc->mtu - sizeof (struct FragmentHeader));
196 if (NULL != fc->tracker)
197 delay = GNUNET_BANDWIDTH_tracker_get_delay (fc->tracker, fsize);
199 delay = GNUNET_TIME_UNIT_ZERO;
202 /* full round transmitted wait 2x delay for ACK before going again */
204 GNUNET_TIME_relative_max (GNUNET_TIME_relative_multiply (delay, 2),
206 /* never use zero, need some time for ACK always */
207 delay = GNUNET_TIME_relative_max (GNUNET_TIME_UNIT_MILLISECONDS, delay);
208 fc->last_round = GNUNET_TIME_absolute_get ();
209 fc->wack = GNUNET_YES;
211 fc->proc_busy = GNUNET_YES;
212 fc->delay_until = GNUNET_TIME_relative_to_absolute (delay);
213 fc->proc (fc->proc_cls, &fh->header);
218 * Create a fragmentation context for the given message.
219 * Fragments the message into fragments of size "mtu" or
220 * less. Calls 'proc' on each un-acknowledged fragment,
221 * using both the expected 'delay' between messages and
222 * acknowledgements and the given 'tracker' to guide the
223 * frequency of calls to 'proc'.
225 * @param stats statistics context
226 * @param mtu the maximum message size for each fragment
227 * @param tracker bandwidth tracker to use for flow control (can be NULL)
228 * @param delay expected delay between fragment transmission
229 * and ACK based on previous messages
230 * @param msg the message to fragment
231 * @param proc function to call for each fragment to transmit
232 * @param proc_cls closure for proc
233 * @return the fragmentation context
235 struct GNUNET_FRAGMENT_Context *
236 GNUNET_FRAGMENT_context_create (struct GNUNET_STATISTICS_Handle *stats,
238 struct GNUNET_BANDWIDTH_Tracker *tracker,
239 struct GNUNET_TIME_Relative delay,
240 const struct GNUNET_MessageHeader *msg,
241 GNUNET_FRAGMENT_MessageProcessor proc,
244 struct GNUNET_FRAGMENT_Context *fc;
248 GNUNET_STATISTICS_update (stats, _("# messages fragmented"), 1, GNUNET_NO);
249 GNUNET_assert (mtu >= 1024 + sizeof (struct FragmentHeader));
250 size = ntohs (msg->size);
251 GNUNET_STATISTICS_update (stats, _("# total size of fragmented messages"),
253 GNUNET_assert (size >= sizeof (struct GNUNET_MessageHeader));
254 fc = GNUNET_malloc (sizeof (struct GNUNET_FRAGMENT_Context) + size);
257 fc->tracker = tracker;
259 fc->msg = (const struct GNUNET_MessageHeader *) &fc[1];
261 fc->proc_cls = proc_cls;
263 GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_WEAK, UINT32_MAX);
264 memcpy (&fc[1], msg, size);
266 (size + mtu - sizeof (struct FragmentHeader) - 1) / (mtu -
269 GNUNET_assert (bits <= 64);
271 fc->acks_mask = UINT64_MAX; /* set all 64 bit */
273 fc->acks_mask = (1LL << bits) - 1; /* set lowest 'bits' bit */
274 fc->acks = fc->acks_mask;
275 fc->task = GNUNET_SCHEDULER_add_now (&transmit_next, fc);
281 * Continuation to call from the 'proc' function after the fragment
282 * has been transmitted (and hence the next fragment can now be
285 * @param fc fragmentation context
288 GNUNET_FRAGMENT_context_transmission_done (struct GNUNET_FRAGMENT_Context *fc)
290 GNUNET_assert (fc->proc_busy == GNUNET_YES);
291 fc->proc_busy = GNUNET_NO;
292 GNUNET_assert (fc->task == GNUNET_SCHEDULER_NO_TASK);
294 GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_absolute_get_remaining
295 (fc->delay_until), &transmit_next, fc);
300 * Process an acknowledgement message we got from the other
301 * side (to control re-transmits).
303 * @param fc fragmentation context
304 * @param msg acknowledgement message we received
305 * @return GNUNET_OK if this ack completes the work of the 'fc'
306 * (all fragments have been received);
307 * GNUNET_NO if more messages are pending
308 * GNUNET_SYSERR if this ack is not valid for this fc
311 GNUNET_FRAGMENT_process_ack (struct GNUNET_FRAGMENT_Context *fc,
312 const struct GNUNET_MessageHeader *msg)
314 const struct FragmentAcknowledgement *fa;
316 struct GNUNET_TIME_Relative ndelay;
318 if (sizeof (struct FragmentAcknowledgement) != ntohs (msg->size))
321 return GNUNET_SYSERR;
323 fa = (const struct FragmentAcknowledgement *) msg;
324 if (ntohl (fa->fragment_id) != fc->fragment_id)
325 return GNUNET_SYSERR; /* not our ACK */
326 abits = GNUNET_ntohll (fa->bits);
327 if (GNUNET_YES == fc->wack)
329 /* normal ACK, can update running average of delay... */
330 fc->wack = GNUNET_NO;
331 ndelay = GNUNET_TIME_absolute_get_duration (fc->last_round);
332 fc->delay.rel_value = (ndelay.rel_value + 3 * fc->delay.rel_value) / 4;
334 GNUNET_STATISTICS_update (fc->stats,
335 _("# fragment acknowledgements received"), 1,
337 if (abits != (fc->acks & abits))
339 /* ID collission or message reordering, count! This should be rare! */
340 GNUNET_STATISTICS_update (fc->stats,
341 _("# bits removed from fragmentation ACKs"), 1,
344 fc->acks = abits & fc->acks_mask;
347 /* more to transmit, do so right now (if tracker permits...) */
348 if (fc->task != GNUNET_SCHEDULER_NO_TASK)
350 /* schedule next transmission now, no point in waiting... */
351 GNUNET_SCHEDULER_cancel (fc->task);
352 fc->task = GNUNET_SCHEDULER_add_now (&transmit_next, fc);
356 /* only case where there is no task should be if we're waiting
357 * for the right to transmit again (proc_busy set to YES) */
358 GNUNET_assert (GNUNET_YES == fc->proc_busy);
364 GNUNET_STATISTICS_update (fc->stats,
365 _("# fragmentation transmissions completed"), 1,
367 if (fc->task != GNUNET_SCHEDULER_NO_TASK)
369 GNUNET_SCHEDULER_cancel (fc->task);
370 fc->task = GNUNET_SCHEDULER_NO_TASK;
377 * Destroy the given fragmentation context (stop calling 'proc', free
380 * @param fc fragmentation context
381 * @return average delay between transmission and ACK for the
382 * last message, FOREVER if the message was not fully transmitted
384 struct GNUNET_TIME_Relative
385 GNUNET_FRAGMENT_context_destroy (struct GNUNET_FRAGMENT_Context *fc)
387 struct GNUNET_TIME_Relative ret;
389 if (fc->task != GNUNET_SCHEDULER_NO_TASK)
390 GNUNET_SCHEDULER_cancel (fc->task);
397 /* end of fragmentation.c */