summaryrefslogtreecommitdiff
path: root/NetworkPkg/Dhcp6Dxe/Dhcp6Impl.c
blob: 934c03ed859a890ef3fff9841036b11f42ed4ab9 (plain)
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
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
/** @file
  This EFI_DHCP6_PROTOCOL interface implementation.

  Copyright (c) 2009 - 2012, Intel Corporation. All rights reserved.<BR>

  This program and the accompanying materials
  are licensed and made available under the terms and conditions of the BSD License
  which accompanies this distribution.  The full text of the license may be found at
  http://opensource.org/licenses/bsd-license.php.

  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.

**/

#include "Dhcp6Impl.h"

//
// Well-known multi-cast address defined in section-24.1 of rfc-3315
//
//   ALL_DHCP_Relay_Agents_and_Servers address: FF02::1:2
//   ALL_DHCP_Servers address:                  FF05::1:3
//
EFI_IPv6_ADDRESS   mAllDhcpRelayAndServersAddress = {{0xFF, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 2}};
EFI_IPv6_ADDRESS   mAllDhcpServersAddress         = {{0xFF, 5, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 3}};

EFI_DHCP6_PROTOCOL gDhcp6ProtocolTemplate = {
  EfiDhcp6GetModeData,
  EfiDhcp6Configure,
  EfiDhcp6Start,
  EfiDhcp6InfoRequest,
  EfiDhcp6RenewRebind,
  EfiDhcp6Decline,
  EfiDhcp6Release,
  EfiDhcp6Stop,
  EfiDhcp6Parse
};

/**
  Starts the DHCPv6 standard S.A.R.R. process.

  The Start() function starts the DHCPv6 standard process. This function can
  be called only when the state of Dhcp6 instance is in the Dhcp6Init state.
  If the DHCP process completes successfully, the state of the Dhcp6 instance
  will be transferred through Dhcp6Selecting and Dhcp6Requesting to the
  Dhcp6Bound state.
  Refer to rfc-3315 for precise state transitions during this process. At the
  time when each event occurs in this process, the callback function that was set
  by EFI_DHCP6_PROTOCOL.Configure() will be called, and the user can take this
  opportunity to control the process.

  @param[in]  This              The pointer to Dhcp6 protocol.

  @retval EFI_SUCCESS           The DHCPv6 standard process has started, or it has
                                completed when CompletionEvent is NULL.
  @retval EFI_ACCESS_DENIED     The EFI DHCPv6 Child instance hasn't been configured.
  @retval EFI_INVALID_PARAMETER This is NULL.
  @retval EFI_OUT_OF_RESOURCES  Required system resources could not be allocated.
  @retval EFI_TIMEOUT           The DHCPv6 configuration process failed because no
                                response was received from the server within the
                                specified timeout value.
  @retval EFI_ABORTED           The user aborted the DHCPv6 process.
  @retval EFI_ALREADY_STARTED   Some other Dhcp6 instance already started the DHCPv6
                                standard process.
  @retval EFI_DEVICE_ERROR      An unexpected system or network error occurred.
  @retval EFI_NO_MEDIA          There was a media error.

**/
EFI_STATUS
EFIAPI
EfiDhcp6Start (
  IN EFI_DHCP6_PROTOCOL        *This
  )
{
  EFI_STATUS                   Status;
  EFI_TPL                      OldTpl;
  DHCP6_INSTANCE               *Instance;
  DHCP6_SERVICE                *Service;

  if (This == NULL) {
    return EFI_INVALID_PARAMETER;
  }

  Instance = DHCP6_INSTANCE_FROM_THIS (This);
  Service  = Instance->Service;

  //
  // The instance hasn't been configured.
  //
  if (Instance->Config == NULL) {
    return EFI_ACCESS_DENIED;
  }

  ASSERT (Instance->IaCb.Ia != NULL);

  //
  // The instance has already been started.
  //
  if (Instance->IaCb.Ia->State != Dhcp6Init) {
    return EFI_ALREADY_STARTED;
  }

  OldTpl           = gBS->RaiseTPL (TPL_CALLBACK);
  Instance->UdpSts = EFI_ALREADY_STARTED;

  //
  // Need to clear initial time to make sure that elapsed-time
  // is set to 0 for first Solicit.
  //
  Instance->StartTime = 0;

  //
  // Send the solicit message to start S.A.R.R process.
  //
  Status = Dhcp6SendSolicitMsg (Instance);

  if (EFI_ERROR (Status)) {
    goto ON_ERROR;
  }

  //
  // Register receive callback for the stateful exchange process.
  //
  Status = UdpIoRecvDatagram(
             Service->UdpIo,
             Dhcp6ReceivePacket,
             Service,
             0
             );

  if (EFI_ERROR (Status) && (Status != EFI_ALREADY_STARTED)) {
    goto ON_ERROR;
  }

  gBS->RestoreTPL (OldTpl);

  //
  // Poll udp out of the net tpl if synchronous call.
  //
  if (Instance->Config->IaInfoEvent == NULL) {

    while (Instance->UdpSts == EFI_ALREADY_STARTED) {
      Service->UdpIo->Protocol.Udp6->Poll (Service->UdpIo->Protocol.Udp6);
    }
    return Instance->UdpSts;
  }

  return EFI_SUCCESS;

ON_ERROR:

  gBS->RestoreTPL (OldTpl);
  return Status;
}


/**
  Stops the DHCPv6 standard S.A.R.R. process.

  The Stop() function is used to stop the DHCPv6 standard process. After this
  function is called successfully, the state of Dhcp6 instance is transferred
  into Dhcp6Init. EFI_DHCP6_PROTOCOL.Configure() needs to be called
  before DHCPv6 standard process can be started again. This function can be
  called when the Dhcp6 instance is in any state.

  @param[in]  This              The pointer to the Dhcp6 protocol.

  @retval EFI_SUCCESS           The Dhcp6 instance is now in the Dhcp6Init state.
  @retval EFI_INVALID_PARAMETER This is NULL.

**/
EFI_STATUS
EFIAPI
EfiDhcp6Stop (
  IN EFI_DHCP6_PROTOCOL        *This
  )
{
  EFI_TPL                      OldTpl;
  EFI_STATUS                   Status;
  EFI_UDP6_PROTOCOL            *Udp6;
  DHCP6_INSTANCE               *Instance;
  DHCP6_SERVICE                *Service;

  if (This == NULL) {
    return EFI_INVALID_PARAMETER;
  }

  Instance = DHCP6_INSTANCE_FROM_THIS (This);
  Service  = Instance->Service;
  Udp6     = Service->UdpIo->Protocol.Udp6;
  Status   = EFI_SUCCESS;

  //
  // The instance hasn't been configured.
  //
  if (Instance->Config == NULL) {
    return Status;
  }

  ASSERT (Instance->IaCb.Ia != NULL);

  //
  // No valid REPLY message received yet, cleanup this instance directly.
  //
  if (Instance->IaCb.Ia->State == Dhcp6Init ||
      Instance->IaCb.Ia->State == Dhcp6Selecting ||
      Instance->IaCb.Ia->State == Dhcp6Requesting
      ) {
    goto ON_EXIT;
  }

  //
  // Release the current ready Ia.
  //
  OldTpl = gBS->RaiseTPL (TPL_CALLBACK);

  Instance->UdpSts = EFI_ALREADY_STARTED;
  Status = Dhcp6SendReleaseMsg (Instance, Instance->IaCb.Ia);
  gBS->RestoreTPL (OldTpl);
  if (EFI_ERROR (Status)) {
    goto ON_EXIT;
  }

  //
  // Poll udp out of the net tpl if synchoronus call.
  //
  if (Instance->Config->IaInfoEvent == NULL) {
    ASSERT (Udp6 != NULL);
    while (Instance->UdpSts == EFI_ALREADY_STARTED) {
      Udp6->Poll (Udp6);
    }
    Status = Instance->UdpSts;
  }
  
ON_EXIT:
  //
  // Clean up the session data for the released Ia.
  //
  OldTpl = gBS->RaiseTPL (TPL_CALLBACK);
  Dhcp6CleanupSession (Instance, EFI_SUCCESS);
  gBS->RestoreTPL (OldTpl);

  return Status;
}


/**
  Returns the current operating mode data for the Dhcp6 instance.

  The GetModeData() function returns the current operating mode and
  cached data packet for the Dhcp6 instance.

  @param[in]  This              The pointer to the Dhcp6 protocol.
  @param[out] Dhcp6ModeData     The pointer to the Dhcp6 mode data.
  @param[out] Dhcp6ConfigData   The pointer to the Dhcp6 configure data.

  @retval EFI_SUCCESS           The mode data was returned.
  @retval EFI_INVALID_PARAMETER This is NULL.
  @retval EFI_ACCESS_DENIED     The EFI DHCPv6 Protocol instance was not
                                configured.
**/
EFI_STATUS
EFIAPI
EfiDhcp6GetModeData (
  IN  EFI_DHCP6_PROTOCOL       *This,
  OUT EFI_DHCP6_MODE_DATA      *Dhcp6ModeData      OPTIONAL,
  OUT EFI_DHCP6_CONFIG_DATA    *Dhcp6ConfigData    OPTIONAL
  )
{
  EFI_TPL                      OldTpl;
  EFI_DHCP6_IA                 *Ia;
  DHCP6_INSTANCE               *Instance;
  DHCP6_SERVICE                *Service;
  UINT32                       IaSize;
  UINT32                       IdSize;

  if (This == NULL || (Dhcp6ModeData == NULL && Dhcp6ConfigData == NULL)) {
    return EFI_INVALID_PARAMETER;
  }

  Instance = DHCP6_INSTANCE_FROM_THIS (This);
  Service  = Instance->Service;

  if (Instance->Config == NULL && Dhcp6ConfigData != NULL) {
    return EFI_ACCESS_DENIED;
  }

  ASSERT (Service->ClientId != NULL);

  OldTpl = gBS->RaiseTPL (TPL_CALLBACK);

  //
  // User needs a copy of instance config data.
  //
  if (Dhcp6ConfigData != NULL) {
    ZeroMem (Dhcp6ConfigData, sizeof(EFI_DHCP6_CONFIG_DATA));
    //
    // Duplicate config data, including all reference buffers.
    //
    if (EFI_ERROR (Dhcp6CopyConfigData (Dhcp6ConfigData, Instance->Config))) {
      goto ON_ERROR;
    }
  }

  //
  // User need a copy of instance mode data.
  //
  if (Dhcp6ModeData != NULL) {
    ZeroMem (Dhcp6ModeData, sizeof (EFI_DHCP6_MODE_DATA));
    //
    // Duplicate a copy of EFI_DHCP6_DUID for client Id.
    //
    IdSize = Service->ClientId->Length + sizeof (Service->ClientId->Length);

    Dhcp6ModeData->ClientId = AllocateZeroPool (IdSize);
    if (Dhcp6ModeData->ClientId == NULL) {
      goto ON_ERROR;
    }

    CopyMem (
      Dhcp6ModeData->ClientId,
      Service->ClientId,
      IdSize
      );

    Ia = Instance->IaCb.Ia;
    if (Ia != NULL) {
      //
      // Duplicate a copy of EFI_DHCP6_IA for configured Ia.
      //
      IaSize = sizeof (EFI_DHCP6_IA) + (Ia->IaAddressCount -1) * sizeof (EFI_DHCP6_IA_ADDRESS);

      Dhcp6ModeData->Ia = AllocateZeroPool (IaSize);
      if (Dhcp6ModeData->Ia == NULL) {
        goto ON_ERROR;
      }

      CopyMem (
        Dhcp6ModeData->Ia,
        Ia,
        IaSize
        );

      //
      // Duplicate a copy of reply packet if has.
      //
      if (Ia->ReplyPacket != NULL) {
        Dhcp6ModeData->Ia->ReplyPacket = AllocateZeroPool (Ia->ReplyPacket->Size);
        if (Dhcp6ModeData->Ia->ReplyPacket == NULL) {
          goto ON_ERROR;
        }
        CopyMem (
          Dhcp6ModeData->Ia->ReplyPacket,
          Ia->ReplyPacket,
          Ia->ReplyPacket->Size
          );
      }
    }
  }

  gBS->RestoreTPL (OldTpl);

  return EFI_SUCCESS;

ON_ERROR:

  if (Dhcp6ConfigData != NULL) {
    Dhcp6CleanupConfigData (Dhcp6ConfigData);
  }
  if (Dhcp6ModeData != NULL) {
    Dhcp6CleanupModeData (Dhcp6ModeData);
  }
  gBS->RestoreTPL (OldTpl);

  return EFI_OUT_OF_RESOURCES;
}


/**
  Initializes, changes, or resets the operational settings for the Dhcp6 instance.

  The Configure() function is used to initialize or clean up the configuration
  data of the Dhcp6 instance:
  - When Dhcp6CfgData is not NULL and Configure() is called successfully, the
    configuration data will be initialized in the Dhcp6 instance, and the state
    of the configured IA will be transferred into Dhcp6Init.
  - When Dhcp6CfgData is NULL and Configure() is called successfully, the
    configuration data will be cleaned up and no IA will be associated with
    the Dhcp6 instance.
  To update the configuration data for an Dhcp6 instance, the original data
  must be cleaned up before setting the new configuration data.

  @param[in]  This                   The pointer to the Dhcp6 protocol
  @param[in]  Dhcp6CfgData           The pointer to the EFI_DHCP6_CONFIG_DATA.

  @retval EFI_SUCCESS           The Dhcp6 is configured successfully with the
                                Dhcp6Init state, or cleaned up the original
                                configuration setting.
  @retval EFI_ACCESS_DENIED     The Dhcp6 instance was already configured.
                                The Dhcp6 instance has already started the
                                DHCPv6 S.A.R.R when Dhcp6CfgData is NULL.
  @retval EFI_INVALID_PARAMETER Some of the parameter is invalid.
  @retval EFI_OUT_OF_RESOURCES  Required system resources could not be allocated.
  @retval EFI_DEVICE_ERROR      An unexpected system or network error occurred.

**/
EFI_STATUS
EFIAPI
EfiDhcp6Configure (
  IN EFI_DHCP6_PROTOCOL        *This,
  IN EFI_DHCP6_CONFIG_DATA     *Dhcp6CfgData    OPTIONAL
  )
{
  EFI_TPL                      OldTpl;
  EFI_STATUS                   Status;
  LIST_ENTRY                   *Entry;
  DHCP6_INSTANCE               *Other;
  DHCP6_INSTANCE               *Instance;
  DHCP6_SERVICE                *Service;
  UINTN                        Index;

  if (This == NULL) {
    return EFI_INVALID_PARAMETER;
  }

  Instance = DHCP6_INSTANCE_FROM_THIS (This);
  Service  = Instance->Service;

  //
  // Check the parameter of configure data.
  //
  if (Dhcp6CfgData != NULL) {
    if (Dhcp6CfgData->OptionCount > 0 && Dhcp6CfgData->OptionList == NULL) {
      return EFI_INVALID_PARAMETER;
    }
    if (Dhcp6CfgData->OptionList != NULL) {
      for (Index = 0; Index < Dhcp6CfgData->OptionCount; Index++) {
        if (Dhcp6CfgData->OptionList[Index]->OpCode == Dhcp6OptClientId ||
            Dhcp6CfgData->OptionList[Index]->OpCode == Dhcp6OptRapidCommit ||
            Dhcp6CfgData->OptionList[Index]->OpCode == Dhcp6OptReconfigureAccept ||
            Dhcp6CfgData->OptionList[Index]->OpCode == Dhcp6OptIana ||
            Dhcp6CfgData->OptionList[Index]->OpCode == Dhcp6OptIata
            ) {
          return EFI_INVALID_PARAMETER;
        }
      }
    }

    if (Dhcp6CfgData->IaDescriptor.Type != EFI_DHCP6_IA_TYPE_NA &&
        Dhcp6CfgData->IaDescriptor.Type != EFI_DHCP6_IA_TYPE_TA
        ) {
      return EFI_INVALID_PARAMETER;
    }

    if (Dhcp6CfgData->IaInfoEvent == NULL && Dhcp6CfgData->SolicitRetransmission == NULL) {
      return EFI_INVALID_PARAMETER;
    }

    if (Dhcp6CfgData->SolicitRetransmission != NULL &&
        Dhcp6CfgData->SolicitRetransmission->Mrc == 0 &&
        Dhcp6CfgData->SolicitRetransmission->Mrd == 0
        ) {
      return EFI_INVALID_PARAMETER;
    }

    //
    // Make sure the (IaId, IaType) is unique over all the instances.
    //
    NET_LIST_FOR_EACH (Entry, &Service->Child) {
      Other = NET_LIST_USER_STRUCT (Entry, DHCP6_INSTANCE, Link);
      if (Other->IaCb.Ia != NULL &&
          Other->IaCb.Ia->Descriptor.Type == Dhcp6CfgData->IaDescriptor.Type &&
          Other->IaCb.Ia->Descriptor.IaId == Dhcp6CfgData->IaDescriptor.IaId
          ) {
        return EFI_INVALID_PARAMETER;
      }
    }
  }

  OldTpl = gBS->RaiseTPL (TPL_CALLBACK);

  if (Dhcp6CfgData != NULL) {
    //
    // It's not allowed to configure one instance twice without configure null.
    //
    if (Instance->Config != NULL) {
      gBS->RestoreTPL (OldTpl);
      return EFI_ACCESS_DENIED;
    }

    //
    // Duplicate config data including all reference buffers.
    //
    Instance->Config = AllocateZeroPool (sizeof (EFI_DHCP6_CONFIG_DATA));
    if (Instance->Config == NULL) {
      gBS->RestoreTPL (OldTpl);
      return EFI_OUT_OF_RESOURCES;
    }

    Status = Dhcp6CopyConfigData (Instance->Config, Dhcp6CfgData);
    if (EFI_ERROR(Status)) {
      FreePool (Instance->Config);
      gBS->RestoreTPL (OldTpl);
      return EFI_OUT_OF_RESOURCES;
    }

    //
    // Initialize the Ia descriptor from the config data, and leave the other
    // fields of the Ia as default value 0.
    //
    Instance->IaCb.Ia = AllocateZeroPool (sizeof(EFI_DHCP6_IA));
    if (Instance->IaCb.Ia == NULL) {
      Dhcp6CleanupConfigData (Instance->Config);
      FreePool (Instance->Config);
      gBS->RestoreTPL (OldTpl);
      return EFI_OUT_OF_RESOURCES;
    }
    CopyMem (
      &Instance->IaCb.Ia->Descriptor,
      &Dhcp6CfgData->IaDescriptor,
      sizeof(EFI_DHCP6_IA_DESCRIPTOR)
      );

  } else {

    if (Instance->Config == NULL) {
      ASSERT (Instance->IaCb.Ia == NULL);
      gBS->RestoreTPL (OldTpl);
      return EFI_SUCCESS;
    }

    //
    // It's not allowed to configure a started instance as null.
    //
    if (Instance->IaCb.Ia->State != Dhcp6Init) {
      gBS->RestoreTPL (OldTpl);
      return EFI_ACCESS_DENIED;
    }

    Dhcp6CleanupConfigData (Instance->Config);
    FreePool (Instance->Config);
    Instance->Config = NULL;

    FreePool (Instance->IaCb.Ia);
    Instance->IaCb.Ia = NULL;
  }

  gBS->RestoreTPL (OldTpl);

  return EFI_SUCCESS;
}


/**
  Request configuration information without the assignment of any
  Ia addresses of the client.

  The InfoRequest() function is used to request configuration information
  without the assignment of any IPv6 address of the client. The client sends
  out an Information Request packet to obtain the required configuration
  information, and DHCPv6 server responds with a Reply packet containing
  the information for the client. The received Reply packet will be passed
  to the user by ReplyCallback function. If the user returns EFI_NOT_READY from
  ReplyCallback, the Dhcp6 instance will continue to receive other Reply
  packets unless timeout according to the Retransmission parameter.
  Otherwise, the Information Request exchange process will be finished
  successfully if user returns EFI_SUCCESS from ReplyCallback.

  @param[in]  This              The pointer to the Dhcp6 protocol.
  @param[in]  SendClientId      If TRUE, the DHCPv6 protocol instance will build Client
                                Identifier option and include it into Information Request
                                packet. Otherwise, Client Identifier option will not be included.
  @param[in]  OptionRequest     The pointer to the buffer of option request options.
  @param[in]  OptionCount       The option number in the OptionList.
  @param[in]  OptionList        The list of appended options.
  @param[in]  Retransmission    The pointer to the retransmission of the message.
  @param[in]  TimeoutEvent      The event of timeout.
  @param[in]  ReplyCallback     The callback function when the reply was received.
  @param[in]  CallbackContext   The pointer to the parameter passed to the callback.

  @retval EFI_SUCCESS           The DHCPv6 information request exchange process
                                completed when TimeoutEvent is NULL. Information
                                Request packet has been sent to DHCPv6 server when
                                TimeoutEvent is not NULL.
  @retval EFI_NO_RESPONSE       The DHCPv6 information request exchange process failed
                                because of no response, or not all requested-options
                                are responded by DHCPv6 servers when Timeout happened.
  @retval EFI_ABORTED           The DHCPv6 information request exchange process was aborted
                                by user.
  @retval EFI_INVALID_PARAMETER Some parameter is NULL.
  @retval EFI_OUT_OF_RESOURCES  Required system resources could not be allocated.
  @retval EFI_DEVICE_ERROR      An unexpected system or network error occurred.

**/
EFI_STATUS
EFIAPI
EfiDhcp6InfoRequest (
  IN EFI_DHCP6_PROTOCOL        *This,
  IN BOOLEAN                   SendClientId,
  IN EFI_DHCP6_PACKET_OPTION   *OptionRequest,
  IN UINT32                    OptionCount,
  IN EFI_DHCP6_PACKET_OPTION   *OptionList[]    OPTIONAL,
  IN EFI_DHCP6_RETRANSMISSION  *Retransmission,
  IN EFI_EVENT                 TimeoutEvent     OPTIONAL,
  IN EFI_DHCP6_INFO_CALLBACK   ReplyCallback,
  IN VOID                      *CallbackContext OPTIONAL
  )
{
  EFI_STATUS                   Status;
  DHCP6_INSTANCE               *Instance;
  DHCP6_SERVICE                *Service;
  UINTN                        Index;
  EFI_EVENT                    Timer;
  EFI_STATUS                   TimerStatus;
  UINTN                        GetMappingTimeOut;

  if (This == NULL || OptionRequest == NULL || Retransmission == NULL || ReplyCallback == NULL) {
    return EFI_INVALID_PARAMETER;
  }

  if (Retransmission != NULL && Retransmission->Mrc == 0 && Retransmission->Mrd == 0) {
    return EFI_INVALID_PARAMETER;
  }

  if (OptionCount > 0 && OptionList == NULL) {
    return EFI_INVALID_PARAMETER;
  }

  if (OptionList != NULL) {
    for (Index = 0; Index < OptionCount; Index++) {
      if (OptionList[Index]->OpCode == Dhcp6OptClientId || OptionList[Index]->OpCode == Dhcp6OptRequestOption) {
        return EFI_INVALID_PARAMETER;
      }
    }
  }

  Instance = DHCP6_INSTANCE_FROM_THIS (This);
  Service  = Instance->Service;

  Status = Dhcp6StartInfoRequest (
             Instance,
             SendClientId,
             OptionRequest,
             OptionCount,
             OptionList,
             Retransmission,
             TimeoutEvent,
             ReplyCallback,
             CallbackContext
             );
  if (Status == EFI_NO_MAPPING) {
    //
    // The link local address is not ready, wait for some time and restart
    // the DHCP6 information request process.
    //
    Status = Dhcp6GetMappingTimeOut(Service->Ip6Cfg, &GetMappingTimeOut);
    if (EFI_ERROR(Status)) {
      return Status;
    }

    Status = gBS->CreateEvent (EVT_TIMER, TPL_CALLBACK, NULL, NULL, &Timer);
    if (EFI_ERROR (Status)) {
      return Status;
    }

    //
    // Start the timer, wait for link local address DAD to finish.
    //
    Status = gBS->SetTimer (Timer, TimerRelative, GetMappingTimeOut);
    if (EFI_ERROR (Status)) {
      gBS->CloseEvent (Timer);
      return Status;
    }

    do {  
      TimerStatus = gBS->CheckEvent (Timer);
      if (!EFI_ERROR (TimerStatus)) {
        Status = Dhcp6StartInfoRequest (
                   Instance,
                   SendClientId,
                   OptionRequest,
                   OptionCount,
                   OptionList,
                   Retransmission,
                   TimeoutEvent,
                   ReplyCallback,
                   CallbackContext
                   );
      }
    } while (TimerStatus == EFI_NOT_READY);
    
    gBS->CloseEvent (Timer);
  }
  if (EFI_ERROR (Status)) {
    return Status;
  }

  //
  // Poll udp out of the net tpl if synchoronus call.
  //
  if (TimeoutEvent == NULL) {

    while (Instance->UdpSts == EFI_ALREADY_STARTED) {
      Service->UdpIo->Protocol.Udp6->Poll (Service->UdpIo->Protocol.Udp6);
    }
    return Instance->UdpSts;
  }

  return EFI_SUCCESS;
}


/**
  Manually extend the valid and preferred lifetimes for the IPv6 addresses
  of the configured IA and update other configuration parameters by sending a
  Renew or Rebind packet.

  The RenewRebind() function is used to manually extend the valid and preferred
  lifetimes for the IPv6 addresses of the configured IA, and update other
  configuration parameters by sending Renew or Rebind packet.
  - When RebindRequest is FALSE and the state of the configured IA is Dhcp6Bound,
    it sends Renew packet to the previously DHCPv6 server and transfer the
    state of the configured IA to Dhcp6Renewing. If valid Reply packet received,
    the state transfers to Dhcp6Bound and the valid and preferred timer restarts.
    If fails, the state transfers to Dhcp6Bound, but the timer continues.
  - When RebindRequest is TRUE and the state of the configured IA is Dhcp6Bound,
    it will send a Rebind packet. If valid Reply packet is received, the state transfers
    to Dhcp6Bound and the valid and preferred timer restarts. If it fails, the state
    transfers to Dhcp6Init, and the IA can't be used.

  @param[in]  This              The pointer to the Dhcp6 protocol.
  @param[in]  RebindRequest     If TRUE, Rebind packet will be sent and enter Dhcp6Rebinding state.
                                Otherwise, Renew packet will be sent and enter Dhcp6Renewing state.

  @retval EFI_SUCCESS           The DHCPv6 renew/rebind exchange process has
                                completed and at least one IPv6 address of the
                                configured IA has been bound again when
                                EFI_DHCP6_CONFIG_DATA.IaInfoEvent is NULL.
                                The EFI DHCPv6 Protocol instance has sent Renew
                                or Rebind packet when
                                EFI_DHCP6_CONFIG_DATA.IaInfoEvent is not NULL.
  @retval EFI_ACCESS_DENIED     The Dhcp6 instance hasn't been configured, or the
                                state of the configured IA is not in Dhcp6Bound.
  @retval EFI_ALREADY_STARTED   The state of the configured IA has already entered
                                Dhcp6Renewing when RebindRequest is FALSE.
                                The state of the configured IA has already entered
                                Dhcp6Rebinding when RebindRequest is TRUE.
  @retval EFI_ABORTED           The DHCPv6 renew/rebind exchange process aborted
                                by the user.
  @retval EFI_NO_RESPONSE       The DHCPv6 renew/rebind exchange process failed
                                because of no response.
  @retval EFI_NO_MAPPING        No IPv6 address has been bound to the configured
                                IA after the DHCPv6 renew/rebind exchange process.
  @retval EFI_INVALID_PARAMETER Some parameter is NULL.
  @retval EFI_DEVICE_ERROR      An unexpected system or network error occurred.

**/
EFI_STATUS
EFIAPI
EfiDhcp6RenewRebind (
  IN EFI_DHCP6_PROTOCOL        *This,
  IN BOOLEAN                   RebindRequest
  )
{
  EFI_STATUS                   Status;
  EFI_TPL                      OldTpl;
  DHCP6_INSTANCE               *Instance;
  DHCP6_SERVICE                *Service;

  if (This == NULL) {
    return EFI_INVALID_PARAMETER;
  }

  Instance = DHCP6_INSTANCE_FROM_THIS (This);
  Service  = Instance->Service;

  //
  // The instance hasn't been configured.
  //
  if (Instance->Config == NULL) {
    return EFI_ACCESS_DENIED;
  }

  ASSERT (Instance->IaCb.Ia != NULL);

  //
  // The instance has already entered renewing or rebinding state.
  //
  if ((Instance->IaCb.Ia->State == Dhcp6Rebinding && RebindRequest) ||
      (Instance->IaCb.Ia->State == Dhcp6Renewing && !RebindRequest)
      ) {
    return EFI_ALREADY_STARTED;
  }

  if (Instance->IaCb.Ia->State != Dhcp6Bound) {
    return EFI_ACCESS_DENIED;
  }

  OldTpl           = gBS->RaiseTPL (TPL_CALLBACK);
  Instance->UdpSts = EFI_ALREADY_STARTED;

  //
  // Send renew/rebind message to start exchange process.
  //
  Status = Dhcp6SendRenewRebindMsg (Instance, RebindRequest);

  if (EFI_ERROR (Status)) {
    goto ON_ERROR;
  }

  //
  // Register receive callback for the stateful exchange process.
  //
  Status = UdpIoRecvDatagram(
             Service->UdpIo,
             Dhcp6ReceivePacket,
             Service,
             0
             );

  if (EFI_ERROR (Status) && (Status != EFI_ALREADY_STARTED)) {
    goto ON_ERROR;
  }

  gBS->RestoreTPL (OldTpl);

  //
  // Poll udp out of the net tpl if synchoronus call.
  //
  if (Instance->Config->IaInfoEvent == NULL) {

    while (Instance->UdpSts == EFI_ALREADY_STARTED) {
      Service->UdpIo->Protocol.Udp6->Poll (Service->UdpIo->Protocol.Udp6);
    }
    return Instance->UdpSts;
  }

  return EFI_SUCCESS;

ON_ERROR:

  gBS->RestoreTPL (OldTpl);
  return Status;
}


/**
  Inform that one or more addresses assigned by a server are already
  in use by another node.

  The Decline() function is used to manually decline the assignment of
  IPv6 addresses, which have been already used by another node. If all
  IPv6 addresses of the configured IA are declined through this function,
  the state of the IA will switch through Dhcp6Declining to Dhcp6Init.
  Otherwise, the state of the IA will restore to Dhcp6Bound after the
  declining process. The Decline() can only be called when the IA is in
  Dhcp6Bound state. If the EFI_DHCP6_CONFIG_DATA.IaInfoEvent is NULL,
  this function is a blocking operation. It will return after the
  declining process finishes, or aborted by user.

  @param[in]  This              The pointer to EFI_DHCP6_PROTOCOL.
  @param[in]  AddressCount      The number of declining addresses.
  @param[in]  Addresses         The pointer to the buffer stored the declining
                                addresses.

  @retval EFI_SUCCESS           The DHCPv6 decline exchange process completed
                                when EFI_DHCP6_CONFIG_DATA.IaInfoEvent was NULL.
                                The Dhcp6 instance sent Decline packet when
                                EFI_DHCP6_CONFIG_DATA.IaInfoEvent was not NULL.
  @retval EFI_ACCESS_DENIED     The Dhcp6 instance hasn't been configured, or the
                                state of the configured IA is not in Dhcp6Bound.
  @retval EFI_ABORTED           The DHCPv6 decline exchange process aborted by user.
  @retval EFI_NOT_FOUND         Any specified IPv6 address is not correlated with
                                the configured IA for this instance.
  @retval EFI_INVALID_PARAMETER Some parameter is NULL.
  @retval EFI_DEVICE_ERROR      An unexpected system or network error occurred.

**/
EFI_STATUS
EFIAPI
EfiDhcp6Decline (
  IN EFI_DHCP6_PROTOCOL        *This,
  IN UINT32                    AddressCount,
  IN EFI_IPv6_ADDRESS          *Addresses
  )
{
  EFI_STATUS                   Status;
  EFI_TPL                      OldTpl;
  EFI_DHCP6_IA                 *DecIa;
  DHCP6_INSTANCE               *Instance;
  DHCP6_SERVICE                *Service;

  if (This == NULL || AddressCount == 0 || Addresses == NULL) {
    return EFI_INVALID_PARAMETER;
  }

  Instance = DHCP6_INSTANCE_FROM_THIS (This);
  Service  = Instance->Service;

  //
  // The instance hasn't been configured.
  //
  if (Instance->Config == NULL) {
    return EFI_ACCESS_DENIED;
  }

  ASSERT (Instance->IaCb.Ia != NULL);

  if (Instance->IaCb.Ia->State != Dhcp6Bound) {
    return EFI_ACCESS_DENIED;
  }

  //
  // Check whether all the declined addresses belongs to the configured Ia.
  //
  Status = Dhcp6CheckAddress (Instance->IaCb.Ia, AddressCount, Addresses);

  if (EFI_ERROR(Status)) {
    return Status;
  }

  OldTpl           = gBS->RaiseTPL (TPL_CALLBACK);
  Instance->UdpSts = EFI_ALREADY_STARTED;

  //
  // Deprive of all the declined addresses from the configured Ia, and create a
  // DeclineIa used to create decline message.
  //
  DecIa = Dhcp6DepriveAddress (Instance->IaCb.Ia, AddressCount, Addresses);

  if (DecIa == NULL) {
    Status = EFI_OUT_OF_RESOURCES;
    goto ON_ERROR;
  }

  //
  // Send the decline message to start exchange process.
  //
  Status = Dhcp6SendDeclineMsg (Instance, DecIa);

  if (EFI_ERROR (Status)) {
    goto ON_ERROR;
  }

  //
  // Register receive callback for the stateful exchange process.
  //
  Status = UdpIoRecvDatagram(
             Service->UdpIo,
             Dhcp6ReceivePacket,
             Service,
             0
             );

  if (EFI_ERROR (Status) && (Status != EFI_ALREADY_STARTED)) {
    goto ON_ERROR;
  }

  FreePool (DecIa);
  gBS->RestoreTPL (OldTpl);

  //
  // Poll udp out of the net tpl if synchoronus call.
  //
  if (Instance->Config->IaInfoEvent == NULL) {

    while (Instance->UdpSts == EFI_ALREADY_STARTED) {
      Service->UdpIo->Protocol.Udp6->Poll (Service->UdpIo->Protocol.Udp6);
    }
    return Instance->UdpSts;
  }

  return EFI_SUCCESS;

ON_ERROR:

  if (DecIa != NULL) {
    FreePool (DecIa);
  }
  gBS->RestoreTPL (OldTpl);

  return Status;
}


/**
  Release one or more addresses associated with the configured Ia
  for current instance.

  The Release() function is used to manually release one or more
  IPv6 addresses. If AddressCount is zero, it will release all IPv6
  addresses of the configured IA. If all IPv6 addresses of the IA are
  released through this function, the state of the IA will switch
  through Dhcp6Releasing to Dhcp6Init, otherwise, the state of the
  IA will restore to Dhcp6Bound after the releasing process.
  The Release() can only be called when the IA is in Dhcp6Bound state.
  If the EFI_DHCP6_CONFIG_DATA.IaInfoEvent is NULL, the function is
  a blocking operation. It will return after the releasing process
  finishes, or is aborted by user.

  @param[in]  This              The pointer to the Dhcp6 protocol.
  @param[in]  AddressCount      The number of releasing addresses.
  @param[in]  Addresses         The pointer to the buffer stored the releasing
                                addresses.

  @retval EFI_SUCCESS           The DHCPv6 release exchange process
                                completed when EFI_DHCP6_CONFIG_DATA.IaInfoEvent
                                was NULL. The Dhcp6 instance was sent Release
                                packet when EFI_DHCP6_CONFIG_DATA.IaInfoEvent
                                was not NULL.
  @retval EFI_ACCESS_DENIED     The Dhcp6 instance hasn't been configured, or the
                                state of the configured IA is not in Dhcp6Bound.
  @retval EFI_ABORTED           The DHCPv6 release exchange process aborted by user.
  @retval EFI_NOT_FOUND         Any specified IPv6 address is not correlated with
                                the configured IA for this instance.
  @retval EFI_INVALID_PARAMETER Some parameter is NULL.
  @retval EFI_DEVICE_ERROR      An unexpected system or network error occurred.

**/
EFI_STATUS
EFIAPI
EfiDhcp6Release (
  IN EFI_DHCP6_PROTOCOL        *This,
  IN UINT32                    AddressCount,
  IN EFI_IPv6_ADDRESS          *Addresses
  )
{
  EFI_STATUS                   Status;
  EFI_TPL                      OldTpl;
  EFI_DHCP6_IA                 *RelIa;
  DHCP6_INSTANCE               *Instance;
  DHCP6_SERVICE                *Service;

  if (This == NULL || (AddressCount != 0 && Addresses == NULL)) {
    return EFI_INVALID_PARAMETER;
  }

  Instance = DHCP6_INSTANCE_FROM_THIS (This);
  Service  = Instance->Service;

  //
  // The instance hasn't been configured.
  //
  if (Instance->Config == NULL) {
    return EFI_ACCESS_DENIED;
  }

  ASSERT (Instance->IaCb.Ia != NULL);

  if (Instance->IaCb.Ia->State != Dhcp6Bound) {
    return EFI_ACCESS_DENIED;
  }

  //
  // Check whether all the released addresses belongs to the configured Ia.
  //
  Status = Dhcp6CheckAddress (Instance->IaCb.Ia, AddressCount, Addresses);

  if (EFI_ERROR(Status)) {
    return Status;
  }

  OldTpl           = gBS->RaiseTPL (TPL_CALLBACK);
  Instance->UdpSts = EFI_ALREADY_STARTED;

  //
  // Deprive of all the released addresses from the configured Ia, and create a
  // ReleaseIa used to create release message.
  //
  RelIa = Dhcp6DepriveAddress (Instance->IaCb.Ia, AddressCount, Addresses);

  if (RelIa == NULL) {
    Status = EFI_OUT_OF_RESOURCES;
    goto ON_ERROR;
  }

  //
  // Send the release message to start exchange process.
  //
  Status = Dhcp6SendReleaseMsg (Instance, RelIa);

  if (EFI_ERROR (Status)) {
    goto ON_ERROR;
  }

  //
  // Register receive callback for the stateful exchange process.
  //
  Status = UdpIoRecvDatagram(
             Service->UdpIo,
             Dhcp6ReceivePacket,
             Service,
             0
             );

  if (EFI_ERROR (Status) && (Status != EFI_ALREADY_STARTED)) {
    goto ON_ERROR;
  }

  FreePool (RelIa);
  gBS->RestoreTPL (OldTpl);

  //
  // Poll udp out of the net tpl if synchoronus call.
  //
  if (Instance->Config->IaInfoEvent == NULL) {
    while (Instance->UdpSts == EFI_ALREADY_STARTED) {
      Service->UdpIo->Protocol.Udp6->Poll (Service->UdpIo->Protocol.Udp6);
    }
    return Instance->UdpSts;
  }

  return EFI_SUCCESS;

ON_ERROR:

  if (RelIa != NULL) {
    FreePool (RelIa);
  }
  gBS->RestoreTPL (OldTpl);

  return Status;
}


/**
  Parse the option data in the Dhcp6 packet.

  The Parse() function is used to retrieve the option list in the DHCPv6 packet.

  @param[in]      This              The pointer to the Dhcp6 protocol.
  @param[in]      Packet            The pointer to the Dhcp6 packet.
  @param[in, out] OptionCount       The number of option in the packet.
  @param[out]     PacketOptionList  The array of pointers to each option in the packet.

  @retval EFI_SUCCESS           The packet was successfully parsed.
  @retval EFI_INVALID_PARAMETER Some parameter is NULL.
  @retval EFI_BUFFER_TOO_SMALL  *OptionCount is smaller than the number of options
                                that were found in the Packet.

**/
EFI_STATUS
EFIAPI
EfiDhcp6Parse (
  IN EFI_DHCP6_PROTOCOL        *This,
  IN EFI_DHCP6_PACKET          *Packet,
  IN OUT UINT32                *OptionCount,
  OUT EFI_DHCP6_PACKET_OPTION  *PacketOptionList[]  OPTIONAL
  )
{
  UINT32                       OptCnt;
  UINT32                       OptLen;
  UINT16                       DataLen;
  UINT8                        *Start;
  UINT8                        *End;

  if (This == NULL || Packet == NULL || OptionCount == NULL) {
    return EFI_INVALID_PARAMETER;
  }

  if (*OptionCount != 0 && PacketOptionList == NULL) {
    return EFI_INVALID_PARAMETER;
  }

  if (Packet->Length > Packet->Size || Packet->Length < sizeof (EFI_DHCP6_HEADER)) {
    return EFI_INVALID_PARAMETER;
  }

  //
  //  The format of Dhcp6 option:
  //
  //     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
  //    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  //    |          option-code          |   option-len (option data)    |
  //    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  //    |                          option-data                          |
  //    |                      (option-len octets)                      |
  //    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  //

  OptCnt = 0;
  OptLen = Packet->Length - sizeof (EFI_DHCP6_HEADER);
  Start  = Packet->Dhcp6.Option;
  End    = Start + OptLen;

  //
  // Calculate the number of option in the packet.
  //
  while (Start < End) {
    DataLen = ((EFI_DHCP6_PACKET_OPTION *) Start)->OpLen;
    Start  += (NTOHS (DataLen) + 4);
    OptCnt++;
  }

  //
  // It will return buffer too small if pass-in option count is smaller than the
  // actual count of options in the packet.
  //
  if (OptCnt > *OptionCount) {
    *OptionCount = OptCnt;
    return EFI_BUFFER_TOO_SMALL;
  }

  ZeroMem (
    PacketOptionList,
    (*OptionCount * sizeof (EFI_DHCP6_PACKET_OPTION *))
    );

  OptCnt = 0;
  Start  = Packet->Dhcp6.Option;

  while (Start < End) {

    PacketOptionList[OptCnt] = (EFI_DHCP6_PACKET_OPTION *) Start;
    DataLen = ((EFI_DHCP6_PACKET_OPTION *) Start)->OpLen;
    Start  += (NTOHS (DataLen) + 4);
    OptCnt++;
  }

  return EFI_SUCCESS;
}