summaryrefslogtreecommitdiff
path: root/libs/enet/peer.c
blob: e1c117f8950ad10181673a259df2d726dc3d20a4 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
/** 
 @file  peer.c
 @brief ENet peer management functions
*/
#include <string.h>
#define ENET_BUILDING_LIB 1
#include "enet/enet.h"

/** @defgroup peer ENet peer functions 
    @{
*/

/** Configures throttle parameter for a peer.

    Unreliable packets are dropped by ENet in response to the varying conditions
    of the Internet connection to the peer.  The throttle represents a probability
    that an unreliable packet should not be dropped and thus sent by ENet to the peer.
    The lowest mean round trip time from the sending of a reliable packet to the
    receipt of its acknowledgement is measured over an amount of time specified by
    the interval parameter in milliseconds.  If a measured round trip time happens to
    be significantly less than the mean round trip time measured over the interval, 
    then the throttle probability is increased to allow more traffic by an amount
    specified in the acceleration parameter, which is a ratio to the ENET_PEER_PACKET_THROTTLE_SCALE
    constant.  If a measured round trip time happens to be significantly greater than
    the mean round trip time measured over the interval, then the throttle probability
    is decreased to limit traffic by an amount specified in the deceleration parameter, which
    is a ratio to the ENET_PEER_PACKET_THROTTLE_SCALE constant.  When the throttle has
    a value of ENET_PEER_PACKET_THROTTLE_SCALE, on unreliable packets are dropped by 
    ENet, and so 100% of all unreliable packets will be sent.  When the throttle has a
    value of 0, all unreliable packets are dropped by ENet, and so 0% of all unreliable
    packets will be sent.  Intermediate values for the throttle represent intermediate
    probabilities between 0% and 100% of unreliable packets being sent.  The bandwidth
    limits of the local and foreign hosts are taken into account to determine a 
    sensible limit for the throttle probability above which it should not raise even in
    the best of conditions.

    @param peer peer to configure 
    @param interval interval, in milliseconds, over which to measure lowest mean RTT; the default value is ENET_PEER_PACKET_THROTTLE_INTERVAL.
    @param acceleration rate at which to increase the throttle probability as mean RTT declines
    @param deceleration rate at which to decrease the throttle probability as mean RTT increases
*/
void
enet_peer_throttle_configure (ENetPeer * peer, enet_uint32 interval, enet_uint32 acceleration, enet_uint32 deceleration)
{
    ENetProtocol command;

    peer -> packetThrottleInterval = interval;
    peer -> packetThrottleAcceleration = acceleration;
    peer -> packetThrottleDeceleration = deceleration;

    command.header.command = ENET_PROTOCOL_COMMAND_THROTTLE_CONFIGURE | ENET_PROTOCOL_COMMAND_FLAG_ACKNOWLEDGE;
    command.header.channelID = 0xFF;

    command.throttleConfigure.packetThrottleInterval = ENET_HOST_TO_NET_32 (interval);
    command.throttleConfigure.packetThrottleAcceleration = ENET_HOST_TO_NET_32 (acceleration);
    command.throttleConfigure.packetThrottleDeceleration = ENET_HOST_TO_NET_32 (deceleration);

    enet_peer_queue_outgoing_command (peer, & command, NULL, 0, 0);
}

int
enet_peer_throttle (ENetPeer * peer, enet_uint32 rtt)
{
    if (peer -> lastRoundTripTime <= peer -> lastRoundTripTimeVariance)
    {
        peer -> packetThrottle = peer -> packetThrottleLimit;
    }
    else
    if (rtt < peer -> lastRoundTripTime)
    {
        peer -> packetThrottle += peer -> packetThrottleAcceleration;

        if (peer -> packetThrottle > peer -> packetThrottleLimit)
          peer -> packetThrottle = peer -> packetThrottleLimit;

        return 1;
    }
    else
    if (rtt > peer -> lastRoundTripTime + 2 * peer -> lastRoundTripTimeVariance)
    {
        if (peer -> packetThrottle > peer -> packetThrottleDeceleration)
          peer -> packetThrottle -= peer -> packetThrottleDeceleration;
        else
          peer -> packetThrottle = 0;

        return -1;
    }

    return 0;
}

/** Queues a packet to be sent.
    @param peer destination for the packet
    @param channelID channel on which to send
    @param packet packet to send
    @retval 0 on success
    @retval < 0 on failure
*/
int
enet_peer_send (ENetPeer * peer, enet_uint8 channelID, ENetPacket * packet)
{
   ENetChannel * channel = & peer -> channels [channelID];
   ENetProtocol command;
   size_t fragmentLength;

   if (peer -> state != ENET_PEER_STATE_CONNECTED ||
       channelID >= peer -> channelCount)
     return -1;

   fragmentLength = peer -> mtu - sizeof (ENetProtocolHeader) - sizeof (ENetProtocolSendFragment);
   if (peer -> host -> checksum != NULL)
     fragmentLength -= sizeof(enet_uint32);

   if (packet -> dataLength > fragmentLength)
   {
      enet_uint16 startSequenceNumber = ENET_HOST_TO_NET_16 (channel -> outgoingReliableSequenceNumber + 1);
      enet_uint32 fragmentCount = ENET_HOST_TO_NET_32 ((packet -> dataLength + fragmentLength - 1) / fragmentLength),
             fragmentNumber,
             fragmentOffset;
      ENetList fragments;
      ENetOutgoingCommand * fragment;

      enet_list_clear (& fragments);

      for (fragmentNumber = 0,
             fragmentOffset = 0;
           fragmentOffset < packet -> dataLength;
           ++ fragmentNumber,
             fragmentOffset += fragmentLength)
      {
         if (packet -> dataLength - fragmentOffset < fragmentLength)
           fragmentLength = packet -> dataLength - fragmentOffset;

         fragment = (ENetOutgoingCommand *) enet_malloc (sizeof (ENetOutgoingCommand));
         if (fragment == NULL)
         {
            while (! enet_list_empty (& fragments))
            {
               fragment = (ENetOutgoingCommand *) enet_list_remove (enet_list_begin (& fragments));
               
               enet_free (fragment);
            }
            
            return -1;
         }
         
         fragment -> fragmentOffset = fragmentOffset;
         fragment -> fragmentLength = fragmentLength;
         fragment -> packet = packet;
         fragment -> command.header.command = ENET_PROTOCOL_COMMAND_SEND_FRAGMENT | ENET_PROTOCOL_COMMAND_FLAG_ACKNOWLEDGE;
         fragment -> command.header.channelID = channelID;
         fragment -> command.sendFragment.startSequenceNumber = startSequenceNumber;
         fragment -> command.sendFragment.dataLength = ENET_HOST_TO_NET_16 (fragmentLength);
         fragment -> command.sendFragment.fragmentCount = fragmentCount;
         fragment -> command.sendFragment.fragmentNumber = ENET_HOST_TO_NET_32 (fragmentNumber);
         fragment -> command.sendFragment.totalLength = ENET_HOST_TO_NET_32 (packet -> dataLength);
         fragment -> command.sendFragment.fragmentOffset = ENET_NET_TO_HOST_32 (fragmentOffset);
        
         enet_list_insert (enet_list_end (& fragments), fragment);
      }

      packet -> referenceCount += fragmentNumber;

      while (! enet_list_empty (& fragments))
      {
         fragment = (ENetOutgoingCommand *) enet_list_remove (enet_list_begin (& fragments));
 
         enet_peer_setup_outgoing_command (peer, fragment);
      }

      return 0;
   }

   command.header.channelID = channelID;

   if (packet -> flags & ENET_PACKET_FLAG_RELIABLE)
   {
      command.header.command = ENET_PROTOCOL_COMMAND_SEND_RELIABLE | ENET_PROTOCOL_COMMAND_FLAG_ACKNOWLEDGE;
      command.sendReliable.dataLength = ENET_HOST_TO_NET_16 (packet -> dataLength);
   }
   else
   if (packet -> flags & ENET_PACKET_FLAG_UNSEQUENCED)
   {
      command.header.command = ENET_PROTOCOL_COMMAND_SEND_UNSEQUENCED | ENET_PROTOCOL_COMMAND_FLAG_UNSEQUENCED;
      command.sendUnsequenced.unsequencedGroup = ENET_HOST_TO_NET_16 (peer -> outgoingUnsequencedGroup + 1);
      command.sendUnsequenced.dataLength = ENET_HOST_TO_NET_16 (packet -> dataLength);
   }
   else 
   if (channel -> outgoingUnreliableSequenceNumber >= 0xFFFF)
   {
      command.header.command = ENET_PROTOCOL_COMMAND_SEND_RELIABLE | ENET_PROTOCOL_COMMAND_FLAG_ACKNOWLEDGE;
      command.sendReliable.dataLength = ENET_HOST_TO_NET_16 (packet -> dataLength);
   }
   else
   {
      command.header.command = ENET_PROTOCOL_COMMAND_SEND_UNRELIABLE;
      command.sendUnreliable.unreliableSequenceNumber = ENET_HOST_TO_NET_16 (channel -> outgoingUnreliableSequenceNumber + 1);
      command.sendUnreliable.dataLength = ENET_HOST_TO_NET_16 (packet -> dataLength);
   }

   if (enet_peer_queue_outgoing_command (peer, & command, packet, 0, packet -> dataLength) == NULL)
     return -1;

   return 0;
}

/** Attempts to dequeue any incoming queued packet.
    @param peer peer to dequeue packets from
    @param channelID holds the channel ID of the channel the packet was received on success
    @returns a pointer to the packet, or NULL if there are no available incoming queued packets
*/
ENetPacket *
enet_peer_receive (ENetPeer * peer, enet_uint8 * channelID)
{
   ENetIncomingCommand * incomingCommand;
   ENetPacket * packet;
   
   if (enet_list_empty (& peer -> dispatchedCommands))
     return NULL;

   incomingCommand = (ENetIncomingCommand *) enet_list_remove (enet_list_begin (& peer -> dispatchedCommands));

   if (channelID != NULL)
     * channelID = incomingCommand -> command.header.channelID;

   packet = incomingCommand -> packet;

   -- packet -> referenceCount;

   if (incomingCommand -> fragments != NULL)
     enet_free (incomingCommand -> fragments);

   enet_free (incomingCommand);

   return packet;
}

static void
enet_peer_reset_outgoing_commands (ENetList * queue)
{
    ENetOutgoingCommand * outgoingCommand;

    while (! enet_list_empty (queue))
    {
       outgoingCommand = (ENetOutgoingCommand *) enet_list_remove (enet_list_begin (queue));

       if (outgoingCommand -> packet != NULL)
       {
          -- outgoingCommand -> packet -> referenceCount;

          if (outgoingCommand -> packet -> referenceCount == 0)
            enet_packet_destroy (outgoingCommand -> packet);
       }

       enet_free (outgoingCommand);
    }
}

static void
enet_peer_reset_incoming_commands (ENetList * queue)
{
    ENetIncomingCommand * incomingCommand;

    while (! enet_list_empty (queue))
    {
       incomingCommand = (ENetIncomingCommand *) enet_list_remove (enet_list_begin (queue));

       if (incomingCommand -> packet != NULL)
       {
          -- incomingCommand -> packet -> referenceCount;

          if (incomingCommand -> packet -> referenceCount == 0)
            enet_packet_destroy (incomingCommand -> packet);
       }

       if (incomingCommand -> fragments != NULL)
         enet_free (incomingCommand -> fragments);

       enet_free (incomingCommand);
    }
}

void
enet_peer_reset_queues (ENetPeer * peer)
{
    ENetChannel * channel;

    if (peer -> needsDispatch)
    {
       enet_list_remove (& peer -> dispatchList);

       peer -> needsDispatch = 0;
    }

    while (! enet_list_empty (& peer -> acknowledgements))
      enet_free (enet_list_remove (enet_list_begin (& peer -> acknowledgements)));

    enet_peer_reset_outgoing_commands (& peer -> sentReliableCommands);
    enet_peer_reset_outgoing_commands (& peer -> sentUnreliableCommands);
    enet_peer_reset_outgoing_commands (& peer -> outgoingReliableCommands);
    enet_peer_reset_outgoing_commands (& peer -> outgoingUnreliableCommands);
    enet_peer_reset_incoming_commands (& peer -> dispatchedCommands);

    if (peer -> channels != NULL && peer -> channelCount > 0)
    {
        for (channel = peer -> channels;
             channel < & peer -> channels [peer -> channelCount];
             ++ channel)
        {
            enet_peer_reset_incoming_commands (& channel -> incomingReliableCommands);
            enet_peer_reset_incoming_commands (& channel -> incomingUnreliableCommands);
        }

        enet_free (peer -> channels);
    }

    peer -> channels = NULL;
    peer -> channelCount = 0;
}

/** Forcefully disconnects a peer.
    @param peer peer to forcefully disconnect
    @remarks The foreign host represented by the peer is not notified of the disconnection and will timeout
    on its connection to the local host.
*/
void
enet_peer_reset (ENetPeer * peer)
{
    peer -> outgoingPeerID = ENET_PROTOCOL_MAXIMUM_PEER_ID;
    peer -> connectID = 0;

    peer -> state = ENET_PEER_STATE_DISCONNECTED;

    peer -> incomingBandwidth = 0;
    peer -> outgoingBandwidth = 0;
    peer -> incomingBandwidthThrottleEpoch = 0;
    peer -> outgoingBandwidthThrottleEpoch = 0;
    peer -> incomingDataTotal = 0;
    peer -> outgoingDataTotal = 0;
    peer -> lastSendTime = 0;
    peer -> lastReceiveTime = 0;
    peer -> nextTimeout = 0;
    peer -> earliestTimeout = 0;
    peer -> packetLossEpoch = 0;
    peer -> packetsSent = 0;
    peer -> packetsLost = 0;
    peer -> packetLoss = 0;
    peer -> packetLossVariance = 0;
    peer -> packetThrottle = ENET_PEER_DEFAULT_PACKET_THROTTLE;
    peer -> packetThrottleLimit = ENET_PEER_PACKET_THROTTLE_SCALE;
    peer -> packetThrottleCounter = 0;
    peer -> packetThrottleEpoch = 0;
    peer -> packetThrottleAcceleration = ENET_PEER_PACKET_THROTTLE_ACCELERATION;
    peer -> packetThrottleDeceleration = ENET_PEER_PACKET_THROTTLE_DECELERATION;
    peer -> packetThrottleInterval = ENET_PEER_PACKET_THROTTLE_INTERVAL;
    peer -> lastRoundTripTime = ENET_PEER_DEFAULT_ROUND_TRIP_TIME;
    peer -> lowestRoundTripTime = ENET_PEER_DEFAULT_ROUND_TRIP_TIME;
    peer -> lastRoundTripTimeVariance = 0;
    peer -> highestRoundTripTimeVariance = 0;
    peer -> roundTripTime = ENET_PEER_DEFAULT_ROUND_TRIP_TIME;
    peer -> roundTripTimeVariance = 0;
    peer -> mtu = peer -> host -> mtu;
    peer -> reliableDataInTransit = 0;
    peer -> outgoingReliableSequenceNumber = 0;
    peer -> windowSize = ENET_PROTOCOL_MAXIMUM_WINDOW_SIZE;
    peer -> incomingUnsequencedGroup = 0;
    peer -> outgoingUnsequencedGroup = 0;
    peer -> eventData = 0;

    memset (peer -> unsequencedWindow, 0, sizeof (peer -> unsequencedWindow));
    
    enet_peer_reset_queues (peer);
}

/** Sends a ping request to a peer.
    @param peer destination for the ping request
    @remarks ping requests factor into the mean round trip time as designated by the 
    roundTripTime field in the ENetPeer structure.  Enet automatically pings all connected
    peers at regular intervals, however, this function may be called to ensure more
    frequent ping requests.
*/
void
enet_peer_ping (ENetPeer * peer)
{
    ENetProtocol command;

    if (peer -> state != ENET_PEER_STATE_CONNECTED)
      return;

    command.header.command = ENET_PROTOCOL_COMMAND_PING | ENET_PROTOCOL_COMMAND_FLAG_ACKNOWLEDGE;
    command.header.channelID = 0xFF;
   
    enet_peer_queue_outgoing_command (peer, & command, NULL, 0, 0);
}

/** Force an immediate disconnection from a peer.
    @param peer peer to disconnect
    @param data data describing the disconnection
    @remarks No ENET_EVENT_DISCONNECT event will be generated. The foreign peer is not
    guarenteed to receive the disconnect notification, and is reset immediately upon
    return from this function.
*/
void
enet_peer_disconnect_now (ENetPeer * peer, enet_uint32 data)
{
    ENetProtocol command;

    if (peer -> state == ENET_PEER_STATE_DISCONNECTED)
      return;

    if (peer -> state != ENET_PEER_STATE_ZOMBIE &&
        peer -> state != ENET_PEER_STATE_DISCONNECTING)
    {
        enet_peer_reset_queues (peer);

        command.header.command = ENET_PROTOCOL_COMMAND_DISCONNECT | ENET_PROTOCOL_COMMAND_FLAG_UNSEQUENCED;
        command.header.channelID = 0xFF;
        command.disconnect.data = ENET_HOST_TO_NET_32 (data);

        enet_peer_queue_outgoing_command (peer, & command, NULL, 0, 0);

        enet_host_flush (peer -> host);
    }

    enet_peer_reset (peer);
}

/** Request a disconnection from a peer.
    @param peer peer to request a disconnection
    @param data data describing the disconnection
    @remarks An ENET_EVENT_DISCONNECT event will be generated by enet_host_service()
    once the disconnection is complete.
*/
void
enet_peer_disconnect (ENetPeer * peer, enet_uint32 data)
{
    ENetProtocol command;

    if (peer -> state == ENET_PEER_STATE_DISCONNECTING ||
        peer -> state == ENET_PEER_STATE_DISCONNECTED ||
        peer -> state == ENET_PEER_STATE_ACKNOWLEDGING_DISCONNECT ||
        peer -> state == ENET_PEER_STATE_ZOMBIE)
      return;

    enet_peer_reset_queues (peer);

    command.header.command = ENET_PROTOCOL_COMMAND_DISCONNECT;
    command.header.channelID = 0xFF;
    command.disconnect.data = ENET_HOST_TO_NET_32 (data);

    if (peer -> state == ENET_PEER_STATE_CONNECTED || peer -> state == ENET_PEER_STATE_DISCONNECT_LATER)
      command.header.command |= ENET_PROTOCOL_COMMAND_FLAG_ACKNOWLEDGE;
    else
      command.header.command |= ENET_PROTOCOL_COMMAND_FLAG_UNSEQUENCED;      
    
    enet_peer_queue_outgoing_command (peer, & command, NULL, 0, 0);

    if (peer -> state == ENET_PEER_STATE_CONNECTED || peer -> state == ENET_PEER_STATE_DISCONNECT_LATER)
      peer -> state = ENET_PEER_STATE_DISCONNECTING;
    else
    {
        enet_host_flush (peer -> host);
        enet_peer_reset (peer);
    }
}

/** Request a disconnection from a peer, but only after all queued outgoing packets are sent.
    @param peer peer to request a disconnection
    @param data data describing the disconnection
    @remarks An ENET_EVENT_DISCONNECT event will be generated by enet_host_service()
    once the disconnection is complete.
*/
void
enet_peer_disconnect_later (ENetPeer * peer, enet_uint32 data)
{   
    if ((peer -> state == ENET_PEER_STATE_CONNECTED || peer -> state == ENET_PEER_STATE_DISCONNECT_LATER) && 
        ! (enet_list_empty (& peer -> outgoingReliableCommands) &&
           enet_list_empty (& peer -> outgoingUnreliableCommands) && 
           enet_list_empty (& peer -> sentReliableCommands)))
    {
        peer -> state = ENET_PEER_STATE_DISCONNECT_LATER;
        peer -> eventData = data;
    }
    else
      enet_peer_disconnect (peer, data);
}

ENetAcknowledgement *
enet_peer_queue_acknowledgement (ENetPeer * peer, const ENetProtocol * command, enet_uint16 sentTime)
{
    ENetAcknowledgement * acknowledgement;

    if (command -> header.channelID < peer -> channelCount)
    {
        ENetChannel * channel = & peer -> channels [command -> header.channelID];
        enet_uint16 reliableWindow = command -> header.reliableSequenceNumber / ENET_PEER_RELIABLE_WINDOW_SIZE,
                    currentWindow = channel -> incomingReliableSequenceNumber / ENET_PEER_RELIABLE_WINDOW_SIZE;

        if (command -> header.reliableSequenceNumber < channel -> incomingReliableSequenceNumber)
           reliableWindow += ENET_PEER_RELIABLE_WINDOWS;

        if (reliableWindow >= currentWindow + ENET_PEER_FREE_RELIABLE_WINDOWS - 1 && reliableWindow <= currentWindow + ENET_PEER_FREE_RELIABLE_WINDOWS)
          return NULL;
    }

    acknowledgement = (ENetAcknowledgement *) enet_malloc (sizeof (ENetAcknowledgement));
    if (acknowledgement == NULL)
      return NULL;

    peer -> outgoingDataTotal += sizeof (ENetProtocolAcknowledge);

    acknowledgement -> sentTime = sentTime;
    acknowledgement -> command = * command;
    
    enet_list_insert (enet_list_end (& peer -> acknowledgements), acknowledgement);
    
    return acknowledgement;
}

void
enet_peer_setup_outgoing_command (ENetPeer * peer, ENetOutgoingCommand * outgoingCommand)
{
    ENetChannel * channel = & peer -> channels [outgoingCommand -> command.header.channelID];

    peer -> outgoingDataTotal += enet_protocol_command_size (outgoingCommand -> command.header.command) + outgoingCommand -> fragmentLength;

    if (outgoingCommand -> command.header.channelID == 0xFF)
    {
       ++ peer -> outgoingReliableSequenceNumber;

       outgoingCommand -> reliableSequenceNumber = peer -> outgoingReliableSequenceNumber;
       outgoingCommand -> unreliableSequenceNumber = 0;
    }
    else
    if (outgoingCommand -> command.header.command & ENET_PROTOCOL_COMMAND_FLAG_ACKNOWLEDGE)
    {
       ++ channel -> outgoingReliableSequenceNumber;
       channel -> outgoingUnreliableSequenceNumber = 0;

       outgoingCommand -> reliableSequenceNumber = channel -> outgoingReliableSequenceNumber;
       outgoingCommand -> unreliableSequenceNumber = 0;
    }
    else
    if (outgoingCommand -> command.header.command & ENET_PROTOCOL_COMMAND_FLAG_UNSEQUENCED)
    {
       ++ peer -> outgoingUnsequencedGroup;

       outgoingCommand -> reliableSequenceNumber = 0;
       outgoingCommand -> unreliableSequenceNumber = 0;
    }
    else
    {
       ++ channel -> outgoingUnreliableSequenceNumber;
        
       outgoingCommand -> reliableSequenceNumber = channel -> outgoingReliableSequenceNumber;
       outgoingCommand -> unreliableSequenceNumber = channel -> outgoingUnreliableSequenceNumber;
    }
   
    outgoingCommand -> sendAttempts = 0;
    outgoingCommand -> sentTime = 0;
    outgoingCommand -> roundTripTimeout = 0;
    outgoingCommand -> roundTripTimeoutLimit = 0;
    outgoingCommand -> command.header.reliableSequenceNumber = ENET_HOST_TO_NET_16 (outgoingCommand -> reliableSequenceNumber);

    if (outgoingCommand -> command.header.command & ENET_PROTOCOL_COMMAND_FLAG_ACKNOWLEDGE)
      enet_list_insert (enet_list_end (& peer -> outgoingReliableCommands), outgoingCommand);
    else
      enet_list_insert (enet_list_end (& peer -> outgoingUnreliableCommands), outgoingCommand);
}

ENetOutgoingCommand *
enet_peer_queue_outgoing_command (ENetPeer * peer, const ENetProtocol * command, ENetPacket * packet, enet_uint32 offset, enet_uint16 length)
{
    ENetOutgoingCommand * outgoingCommand = (ENetOutgoingCommand *) enet_malloc (sizeof (ENetOutgoingCommand));
    if (outgoingCommand == NULL)
      return NULL;

    outgoingCommand -> command = * command;
    outgoingCommand -> fragmentOffset = offset;
    outgoingCommand -> fragmentLength = length;
    outgoingCommand -> packet = packet;
    if (packet != NULL)
      ++ packet -> referenceCount;

    enet_peer_setup_outgoing_command (peer, outgoingCommand);

    return outgoingCommand;
}

void
enet_peer_dispatch_incoming_unreliable_commands (ENetPeer * peer, ENetChannel * channel)
{
    ENetListIterator currentCommand;

    for (currentCommand = enet_list_begin (& channel -> incomingUnreliableCommands);
         currentCommand != enet_list_end (& channel -> incomingUnreliableCommands);
         currentCommand = enet_list_next (currentCommand))
    {
       ENetIncomingCommand * incomingCommand = (ENetIncomingCommand *) currentCommand;

       if ((incomingCommand -> command.header.command & ENET_PROTOCOL_COMMAND_MASK) == ENET_PROTOCOL_COMMAND_SEND_UNRELIABLE &&
           incomingCommand -> reliableSequenceNumber != channel -> incomingReliableSequenceNumber)
         break;
    }

    if (currentCommand == enet_list_begin (& channel -> incomingUnreliableCommands))
      return;

    enet_list_move (enet_list_end (& peer -> dispatchedCommands), enet_list_begin (& channel -> incomingUnreliableCommands), enet_list_previous (currentCommand));

    if (! peer -> needsDispatch)
    {
       enet_list_insert (enet_list_end (& peer -> host -> dispatchQueue), & peer -> dispatchList);

       peer -> needsDispatch = 1;
    }
}

void
enet_peer_dispatch_incoming_reliable_commands (ENetPeer * peer, ENetChannel * channel)
{
    ENetListIterator currentCommand;

    for (currentCommand = enet_list_begin (& channel -> incomingReliableCommands);
         currentCommand != enet_list_end (& channel -> incomingReliableCommands);
         currentCommand = enet_list_next (currentCommand))
    {
       ENetIncomingCommand * incomingCommand = (ENetIncomingCommand *) currentCommand;
         
       if (incomingCommand -> fragmentsRemaining > 0 ||
           incomingCommand -> reliableSequenceNumber != (enet_uint16) (channel -> incomingReliableSequenceNumber + 1))
         break;

       channel -> incomingReliableSequenceNumber = incomingCommand -> reliableSequenceNumber;

       if (incomingCommand -> fragmentCount > 0)
         channel -> incomingReliableSequenceNumber += incomingCommand -> fragmentCount - 1;
    } 

    if (currentCommand == enet_list_begin (& channel -> incomingReliableCommands))
      return;

    enet_list_move (enet_list_end (& peer -> dispatchedCommands), enet_list_begin (& channel -> incomingReliableCommands), enet_list_previous (currentCommand));

    if (! peer -> needsDispatch)
    {
       enet_list_insert (enet_list_end (& peer -> host -> dispatchQueue), & peer -> dispatchList);

       peer -> needsDispatch = 1;
    }

    enet_peer_dispatch_incoming_unreliable_commands (peer, channel);
}

ENetIncomingCommand *
enet_peer_queue_incoming_command (ENetPeer * peer, const ENetProtocol * command, ENetPacket * packet, enet_uint32 fragmentCount)
{
    static ENetIncomingCommand dummyCommand;

    ENetChannel * channel = & peer -> channels [command -> header.channelID];
    enet_uint32 unreliableSequenceNumber = 0, reliableSequenceNumber;
    enet_uint16 reliableWindow, currentWindow;
    ENetIncomingCommand * incomingCommand;
    ENetListIterator currentCommand;

    if (peer -> state == ENET_PEER_STATE_DISCONNECT_LATER)
      goto freePacket;

    if ((command -> header.command & ENET_PROTOCOL_COMMAND_MASK) != ENET_PROTOCOL_COMMAND_SEND_UNSEQUENCED)
    {
        reliableSequenceNumber = command -> header.reliableSequenceNumber;
        reliableWindow = reliableSequenceNumber / ENET_PEER_RELIABLE_WINDOW_SIZE;
        currentWindow = channel -> incomingReliableSequenceNumber / ENET_PEER_RELIABLE_WINDOW_SIZE;

        if (reliableSequenceNumber < channel -> incomingReliableSequenceNumber)
           reliableWindow += ENET_PEER_RELIABLE_WINDOWS;

        if (reliableWindow < currentWindow || reliableWindow >= currentWindow + ENET_PEER_FREE_RELIABLE_WINDOWS - 1)
          goto freePacket;
    }
                    
    switch (command -> header.command & ENET_PROTOCOL_COMMAND_MASK)
    {
    case ENET_PROTOCOL_COMMAND_SEND_FRAGMENT:
    case ENET_PROTOCOL_COMMAND_SEND_RELIABLE:
       if (reliableSequenceNumber == channel -> incomingReliableSequenceNumber)
           goto freePacket;
       
       for (currentCommand = enet_list_previous (enet_list_end (& channel -> incomingReliableCommands));
            currentCommand != enet_list_end (& channel -> incomingReliableCommands);
            currentCommand = enet_list_previous (currentCommand))
       {
          incomingCommand = (ENetIncomingCommand *) currentCommand;

          if (reliableSequenceNumber >= channel -> incomingReliableSequenceNumber)
          {
             if (incomingCommand -> reliableSequenceNumber < channel -> incomingReliableSequenceNumber)
               continue;
          }
          else
          if (incomingCommand -> reliableSequenceNumber >= channel -> incomingReliableSequenceNumber)
            break;

          if (incomingCommand -> reliableSequenceNumber <= reliableSequenceNumber)
          {
             if (incomingCommand -> reliableSequenceNumber < reliableSequenceNumber)
               break;

             goto freePacket;
          }
       }
       break;

    case ENET_PROTOCOL_COMMAND_SEND_UNRELIABLE:
       unreliableSequenceNumber = ENET_NET_TO_HOST_16 (command -> sendUnreliable.unreliableSequenceNumber);

       for (currentCommand = enet_list_previous (enet_list_end (& channel -> incomingUnreliableCommands));
            currentCommand != enet_list_end (& channel -> incomingUnreliableCommands);
            currentCommand = enet_list_previous (currentCommand))
       {
          incomingCommand = (ENetIncomingCommand *) currentCommand;

          if ((incomingCommand -> command.header.command & ENET_PROTOCOL_COMMAND_MASK) != ENET_PROTOCOL_COMMAND_SEND_UNRELIABLE)
            continue;

          if (reliableSequenceNumber >= channel -> incomingReliableSequenceNumber)
          {
             if (incomingCommand -> reliableSequenceNumber < channel -> incomingReliableSequenceNumber)
               continue;
          }
          else
          if (incomingCommand -> reliableSequenceNumber >= channel -> incomingReliableSequenceNumber)
            break;

          if (incomingCommand -> reliableSequenceNumber < reliableSequenceNumber)
            break;

          if (incomingCommand -> reliableSequenceNumber > reliableSequenceNumber)
            continue;

          if (incomingCommand -> unreliableSequenceNumber <= unreliableSequenceNumber)
          {
             if (incomingCommand -> unreliableSequenceNumber < unreliableSequenceNumber)
               break;

             goto freePacket;
          }
       }
       break;

    case ENET_PROTOCOL_COMMAND_SEND_UNSEQUENCED:
       currentCommand = enet_list_end (& channel -> incomingUnreliableCommands);
       break;

    default:
       goto freePacket;
    }

    incomingCommand = (ENetIncomingCommand *) enet_malloc (sizeof (ENetIncomingCommand));
    if (incomingCommand == NULL)
      goto notifyError;

    incomingCommand -> reliableSequenceNumber = command -> header.reliableSequenceNumber;
    incomingCommand -> unreliableSequenceNumber = unreliableSequenceNumber & 0xFFFF;
    incomingCommand -> command = * command;
    incomingCommand -> fragmentCount = fragmentCount;
    incomingCommand -> fragmentsRemaining = fragmentCount;
    incomingCommand -> packet = packet;
    incomingCommand -> fragments = NULL;
    
    if (fragmentCount > 0)
    { 
       incomingCommand -> fragments = (enet_uint32 *) enet_malloc ((fragmentCount + 31) / 32 * sizeof (enet_uint32));
       if (incomingCommand -> fragments == NULL)
       {
          enet_free (incomingCommand);

          goto notifyError;
       }
       memset (incomingCommand -> fragments, 0, (fragmentCount + 31) / 32 * sizeof (enet_uint32));
    }

    if (packet != NULL)
      ++ packet -> referenceCount;

    enet_list_insert (enet_list_next (currentCommand), incomingCommand);

    switch (command -> header.command & ENET_PROTOCOL_COMMAND_MASK)
    {
    case ENET_PROTOCOL_COMMAND_SEND_FRAGMENT:
    case ENET_PROTOCOL_COMMAND_SEND_RELIABLE:
       enet_peer_dispatch_incoming_reliable_commands (peer, channel);
       break;

    default:
       enet_peer_dispatch_incoming_unreliable_commands (peer, channel);
       break;
    }

    return incomingCommand;

freePacket:
    if (fragmentCount > 0)
      goto notifyError;

    if (packet != NULL && packet -> referenceCount == 0)
      enet_packet_destroy (packet);

    return & dummyCommand;

notifyError:
    if (packet != NULL && packet -> referenceCount == 0)
      enet_packet_destroy (packet);

    return NULL;
}

/** @} */