aboutsummaryrefslogtreecommitdiff
path: root/include/wspiapi.h
blob: eaa4ec2f48c5fc7083c4db6e542ae20c6222b1a1 (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
/*++

Copyright (c) 2000, Microsoft Corporation

Module Name:
    wspiapi.h

Abstract:
    The file contains protocol independent API functions.

Revision History:
    Wed Jul 12 10:50:31 2000, Created

--*/

#ifndef _WSPIAPI_H_
#define _WSPIAPI_H_

#include <stdio.h>              // sprintf()
#include <stdlib.h>             // calloc(), strtoul()
#include <malloc.h>             // calloc()
#include <string.h>             // strlen(), strcmp(), strstr()

#define WspiapiMalloc(tSize)    calloc(1, (tSize))
#define WspiapiFree(p)          free(p)
#define WspiapiSwap(a, b, c)    { (c) = (a); (a) = (b); (b) = (c); }
#define getaddrinfo             WspiapiGetAddrInfo
#define getnameinfo             WspiapiGetNameInfo
#define freeaddrinfo            WspiapiFreeAddrInfo

typedef int (WINAPI *WSPIAPI_PGETADDRINFO) (
    IN  const char                      *nodename,
    IN  const char                      *servname,
    IN  const struct addrinfo           *hints,
    OUT struct addrinfo                 **res);

typedef int (WINAPI *WSPIAPI_PGETNAMEINFO) (
    IN  const struct sockaddr           *sa,
    IN  socklen_t                       salen,
    OUT char                            *host,
    IN  size_t                          hostlen,
    OUT char                            *serv,
    IN  size_t                          servlen,
    IN  int                             flags);

typedef void (WINAPI *WSPIAPI_PFREEADDRINFO) (
    IN  struct addrinfo                 *ai);



#ifdef __cplusplus
extern "C" {
#endif

////////////////////////////////////////////////////////////
// v4 only versions of getaddrinfo and friends.
// NOTE: gai_strerror is inlined in ws2tcpip.h
////////////////////////////////////////////////////////////

__inline
char *
WINAPI
WspiapiStrdup (
	IN  const char *                    pszString)
/*++

Routine Description
    allocates enough storage via calloc() for a copy of the string,
    copies the string into the new memory, and returns a pointer to it.

Arguments
    pszString       string to copy into new memory

Return Value
    a pointer to the newly allocated storage with the string in it.
    NULL if enough memory could not be allocated, or string was NULL.

--*/
{
    char    *pszMemory;

    if (!pszString)
        return(NULL);

    pszMemory = (char *) WspiapiMalloc(strlen(pszString) + 1);
    if (!pszMemory)
        return(NULL);

    return(strcpy(pszMemory, pszString));
}



__inline
BOOL
WINAPI
WspiapiParseV4Address (
    IN  const char *                    pszAddress,
    OUT PDWORD                          pdwAddress)
/*++

Routine Description
    get the IPv4 address (in network byte order) from its string
    representation.  the syntax should be a.b.c.d.

Arguments
    pszArgument         string representation of the IPv4 address
    ptAddress           pointer to the resulting IPv4 address

Return Value
    Returns FALSE if there is an error, TRUE for success.

--*/
{
    DWORD       dwAddress   = 0;
    const char  *pcNext     = NULL;
    int         iCount      = 0;

    // ensure there are 3 '.' (periods)
    for (pcNext = pszAddress; *pcNext != '\0'; pcNext++)
        if (*pcNext == '.')
            iCount++;
    if (iCount != 3)
        return FALSE;

    // return an error if dwAddress is INADDR_NONE (255.255.255.255)
    // since this is never a valid argument to getaddrinfo.
    dwAddress = inet_addr(pszAddress);
    if (dwAddress == INADDR_NONE)
        return FALSE;

    *pdwAddress = dwAddress;
    return TRUE;
}



__inline
struct addrinfo *
WINAPI
WspiapiNewAddrInfo (
    IN  int                             iSocketType,
    IN  int                             iProtocol,
    IN  WORD                            wPort,
    IN  DWORD                           dwAddress)
/*++

Routine Description
    allocate an addrinfo structure and populate fields.
    IPv4 specific internal function, not exported.

Arguments
    iSocketType         SOCK_*.  can be wildcarded (zero).
    iProtocol           IPPROTO_*.  can be wildcarded (zero).
    wPort               port number of service (in network order).
    dwAddress           IPv4 address (in network order).

Return Value
    returns an addrinfo struct, or NULL if out of memory.

--*/
{
    struct addrinfo     *ptNew;
    struct sockaddr_in  *ptAddress;

    // allocate a new addrinfo structure.
    ptNew       =
        (struct addrinfo *) WspiapiMalloc(sizeof(struct addrinfo));
    if (!ptNew)
        return NULL;

    ptAddress   =
        (struct sockaddr_in *) WspiapiMalloc(sizeof(struct sockaddr_in));
    if (!ptAddress)
    {
        WspiapiFree(ptNew);
        return NULL;
    }
    ptAddress->sin_family       = AF_INET;
    ptAddress->sin_port         = wPort;
    ptAddress->sin_addr.s_addr  = dwAddress;

    // fill in the fields...
    ptNew->ai_family            = PF_INET;
    ptNew->ai_socktype          = iSocketType;
    ptNew->ai_protocol          = iProtocol;
    ptNew->ai_addrlen           = sizeof(struct sockaddr_in);
    ptNew->ai_addr              = (struct sockaddr *) ptAddress;

    return ptNew;
}



__inline
int
WINAPI
WspiapiQueryDNS(
    IN  const char                      *pszNodeName,
    IN  int                             iSocketType,
    IN  int                             iProtocol,
    IN  WORD                            wPort,
    OUT char                            *pszAlias,
    OUT struct addrinfo                 **pptResult)
/*++

Routine Description
    helper routine for WspiapiLookupNode.
    performs name resolution by querying the DNS for A records.
    *pptResult would need to be freed if an error is returned.

Arguments
    pszNodeName         name of node to resolve.
    iSocketType         SOCK_*.  can be wildcarded (zero).
    iProtocol           IPPROTO_*.  can be wildcarded (zero).
    wPort               port number of service (in network order).
    pszAlias            where to return the alias.
    pptResult           where to return the result.

Return Value
    Returns 0 on success, an EAI_* style error value otherwise.

--*/
{
    struct addrinfo **pptNext   = pptResult;
    struct hostent  *ptHost     = NULL;
    char            **ppAddresses;

    *pptNext    = NULL;
    pszAlias[0] = '\0';

    ptHost = gethostbyname(pszNodeName);
    if (ptHost)
    {
        if ((ptHost->h_addrtype == AF_INET)     &&
            (ptHost->h_length   == sizeof(struct in_addr)))
        {
            for (ppAddresses    = ptHost->h_addr_list;
                 *ppAddresses   != NULL;
                 ppAddresses++)
            {
                // create an addrinfo structure...
                *pptNext = WspiapiNewAddrInfo(
                    iSocketType,
                    iProtocol,
                    wPort,
                    ((struct in_addr *) *ppAddresses)->s_addr);
                if (!*pptNext)
                    return EAI_MEMORY;

                pptNext = &((*pptNext)->ai_next);
            }
        }

        // pick up the canonical name.
        strcpy(pszAlias, ptHost->h_name);
        return 0;
    }

    switch (WSAGetLastError())
    {
        case WSAHOST_NOT_FOUND: return EAI_NONAME;
        case WSATRY_AGAIN:      return EAI_AGAIN;
        case WSANO_RECOVERY:    return EAI_FAIL;
        case WSANO_DATA:        return EAI_NODATA;
        default:                return EAI_NONAME;
    }
}



__inline
int
WINAPI
WspiapiLookupNode(
    IN  const char                      *pszNodeName,
    IN  int                             iSocketType,
    IN  int                             iProtocol,
    IN  WORD                            wPort,
    IN  BOOL                            bAI_CANONNAME,
    OUT struct addrinfo                 **pptResult)
/*++

Routine Description
    resolve a nodename and return a list of addrinfo structures.
    IPv4 specific internal function, not exported.
    *pptResult would need to be freed if an error is returned.

    NOTE: if bAI_CANONNAME is true, the canonical name should be
          returned in the first addrinfo structure.

Arguments
    pszNodeName         name of node to resolve.
    iSocketType         SOCK_*.  can be wildcarded (zero).
    iProtocol           IPPROTO_*.  can be wildcarded (zero).
    wPort               port number of service (in network order).
    bAI_CANONNAME       whether the AI_CANONNAME flag is set.
    pptResult           where to return result.

Return Value
    Returns 0 on success, an EAI_* style error value otherwise.

--*/
{
    int     iError              = 0;
    int     iAliasCount         = 0;

    char    szFQDN1[NI_MAXHOST] = "";
    char    szFQDN2[NI_MAXHOST] = "";
    char    *pszName            = szFQDN1;
    char    *pszAlias           = szFQDN2;
    char    *pszScratch         = NULL;
    strcpy(pszName, pszNodeName);

    for (;;)
    {
        iError = WspiapiQueryDNS(pszNodeName,
                                 iSocketType,
                                 iProtocol,
                                 wPort,
                                 pszAlias,
                                 pptResult);
        if (iError)
            break;

        // if we found addresses, then we are done.
        if (*pptResult)
            break;

        // stop infinite loops due to DNS misconfiguration.  there appears
        // to be no particular recommended limit in RFCs 1034 and 1035.
        if ((!strlen(pszAlias))             ||
            (!strcmp(pszName, pszAlias))    ||
            (++iAliasCount == 16))
        {
            iError = EAI_FAIL;
            break;
        }

        // there was a new CNAME, look again.
        WspiapiSwap(pszName, pszAlias, pszScratch);
    }

    if (!iError && bAI_CANONNAME)
    {
        (*pptResult)->ai_canonname = WspiapiStrdup(pszAlias);
        if (!(*pptResult)->ai_canonname)
            iError = EAI_MEMORY;
    }

    return iError;
}



__inline
int
WINAPI
WspiapiClone (
    IN  WORD                            wPort,
    IN  struct addrinfo                 *ptResult)
/*++

Routine Description
    clone every addrinfo structure in ptResult for the UDP service.
    ptResult would need to be freed if an error is returned.

Arguments
    wPort               port number of UDP service.
    ptResult            list of addrinfo structures, each
                        of whose node needs to be cloned.

Return Value
    Returns 0 on success, an EAI_MEMORY on allocation failure.

--*/
{
    struct addrinfo *ptNext = NULL;
    struct addrinfo *ptNew  = NULL;

    for (ptNext = ptResult; ptNext != NULL; )
    {
        // create an addrinfo structure...
        ptNew = WspiapiNewAddrInfo(
            SOCK_DGRAM,
            ptNext->ai_protocol,
            wPort,
            ((struct sockaddr_in *) ptNext->ai_addr)->sin_addr.s_addr);
        if (!ptNew)
            break;

        // link the cloned addrinfo
        ptNew->ai_next  = ptNext->ai_next;
        ptNext->ai_next = ptNew;
        ptNext          = ptNew->ai_next;
    }

    if (ptNext != NULL)
        return EAI_MEMORY;

    return 0;
}



__inline
void
WINAPI
WspiapiLegacyFreeAddrInfo (
    IN  struct addrinfo                 *ptHead)
/*++

Routine Description
    Free an addrinfo structure (or chain of structures).
    As specified in RFC 2553, Section 6.4.

Arguments
    ptHead              structure (chain) to free

--*/
{
    struct addrinfo *ptNext;    // next strcture to free

    for (ptNext = ptHead; ptNext != NULL; ptNext = ptHead)
    {
        if (ptNext->ai_canonname)
            WspiapiFree(ptNext->ai_canonname);

        if (ptNext->ai_addr)
            WspiapiFree(ptNext->ai_addr);

        ptHead = ptNext->ai_next;
        WspiapiFree(ptNext);
    }
}



__inline
int
WINAPI
WspiapiLegacyGetAddrInfo(
    IN const char                       *pszNodeName,
    IN const char                       *pszServiceName,
    IN const struct addrinfo            *ptHints,
    OUT struct addrinfo                 **pptResult)
/*++

Routine Description
    Protocol-independent name-to-address translation.
    As specified in RFC 2553, Section 6.4.
    This is the hacked version that only supports IPv4.

Arguments
    pszNodeName         node name to lookup.
    pszServiceName      service name to lookup.
    ptHints             hints about how to process request.
    pptResult           where to return result.

Return Value
    returns zero if successful, an EAI_* error code if not.

--*/
{
    int                 iError      = 0;
    int                 iFlags      = 0;
    int                 iFamily     = PF_UNSPEC;
    int                 iSocketType = 0;
    int                 iProtocol   = 0;
    WORD                wPort       = 0;
    DWORD               dwAddress   = 0;

    struct servent      *ptService  = NULL;
    char                *pc         = NULL;
    BOOL                bClone      = FALSE;
    WORD                wTcpPort    = 0;
    WORD                wUdpPort    = 0;


    // initialize pptResult with default return value.
    *pptResult  = NULL;


    ////////////////////////////////////////
    // validate arguments...
    //

    // both the node name and the service name can't be NULL.
    if ((!pszNodeName) && (!pszServiceName))
        return EAI_NONAME;

    // validate hints.
    if (ptHints)
    {
        // all members other than ai_flags, ai_family, ai_socktype
        // and ai_protocol must be zero or a null pointer.
        if ((ptHints->ai_addrlen    != 0)       ||
            (ptHints->ai_canonname  != NULL)    ||
            (ptHints->ai_addr       != NULL)    ||
            (ptHints->ai_next       != NULL))
        {
            return EAI_FAIL;
        }

        // the spec has the "bad flags" error code, so presumably we
        // should check something here.  insisting that there aren't
        // any unspecified flags set would break forward compatibility,
        // however.  so we just check for non-sensical combinations.
        //
        // we cannot come up with a canonical name given a null node name.
        iFlags      = ptHints->ai_flags;
        if ((iFlags & AI_CANONNAME) && !pszNodeName)
            return EAI_BADFLAGS;

        // we only support a limited number of protocol families.
        iFamily     = ptHints->ai_family;
        if ((iFamily != PF_UNSPEC) && (iFamily != PF_INET))
            return EAI_FAMILY;

        // we only support only these socket types.
        iSocketType = ptHints->ai_socktype;
        if ((iSocketType != 0)                  &&
            (iSocketType != SOCK_STREAM)        &&
            (iSocketType != SOCK_DGRAM)         &&
            (iSocketType != SOCK_RAW))
            return EAI_SOCKTYPE;

        // REVIEW: What if ai_socktype and ai_protocol are at odds?
        iProtocol   = ptHints->ai_protocol;
    }


    ////////////////////////////////////////
    // do service lookup...

    if (pszServiceName)
    {
        wPort = (WORD) strtoul(pszServiceName, &pc, 10);
        if (*pc == '\0')        // numeric port string
        {
            wPort = wTcpPort = wUdpPort = htons(wPort);
            if (iSocketType == 0)
            {
                bClone      = TRUE;
                iSocketType = SOCK_STREAM;
            }
        }
        else                    // non numeric port string
        {
            if ((iSocketType == 0) || (iSocketType == SOCK_DGRAM))
            {
                ptService = getservbyname(pszServiceName, "udp");
                if (ptService)
                    wPort = wUdpPort = ptService->s_port;
            }

            if ((iSocketType == 0) || (iSocketType == SOCK_STREAM))
            {
                ptService = getservbyname(pszServiceName, "tcp");
                if (ptService)
                    wPort = wTcpPort = ptService->s_port;
            }

            // assumes 0 is an invalid service port...
            if (wPort == 0)     // no service exists
                return (iSocketType ? EAI_SERVICE : EAI_NONAME);

            if (iSocketType == 0)
            {
                // if both tcp and udp, process tcp now & clone udp later.
                iSocketType = (wTcpPort) ? SOCK_STREAM : SOCK_DGRAM;
                bClone      = (wTcpPort && wUdpPort);
            }
        }
    }



    ////////////////////////////////////////
    // do node name lookup...

    // if we weren't given a node name,
    // return the wildcard or loopback address (depending on AI_PASSIVE).
    //
    // if we have a numeric host address string,
    // return the binary address.
    //
    if ((!pszNodeName) || (WspiapiParseV4Address(pszNodeName, &dwAddress)))
    {
        if (!pszNodeName)
        {
            dwAddress = htonl((iFlags & AI_PASSIVE)
                              ? INADDR_ANY
                              : INADDR_LOOPBACK);
        }

        // create an addrinfo structure...
        *pptResult =
            WspiapiNewAddrInfo(iSocketType, iProtocol, wPort, dwAddress);
        if (!(*pptResult))
            iError = EAI_MEMORY;

        if (!iError && pszNodeName)
        {
            // implementation specific behavior: set AI_NUMERICHOST
            // to indicate that we got a numeric host address string.
            (*pptResult)->ai_flags |= AI_NUMERICHOST;

            // return the numeric address string as the canonical name
            if (iFlags & AI_CANONNAME)
            {
                (*pptResult)->ai_canonname =
                    WspiapiStrdup(inet_ntoa(*((struct in_addr *) &dwAddress)));
                if (!(*pptResult)->ai_canonname)
                    iError = EAI_MEMORY;
            }
        }
    }


    // if we do not have a numeric host address string and
    // AI_NUMERICHOST flag is set, return an error!
    else if (iFlags & AI_NUMERICHOST)
    {
        iError = EAI_NONAME;
    }


    // since we have a non-numeric node name,
    // we have to do a regular node name lookup.
    else
    {
        iError = WspiapiLookupNode(pszNodeName,
                                   iSocketType,
                                   iProtocol,
                                   wPort,
                                   (iFlags & AI_CANONNAME),
                                   pptResult);
    }

    if (!iError && bClone)
    {
        iError = WspiapiClone(wUdpPort, *pptResult);
    }

    if (iError)
    {
        WspiapiLegacyFreeAddrInfo(*pptResult);
        *pptResult  = NULL;
    }

    return (iError);
}



__inline
int
WINAPI
WspiapiLegacyGetNameInfo(
    IN  const struct sockaddr           *ptSocketAddress,
    IN  socklen_t                       tSocketLength,
    OUT char                            *pszNodeName,
    IN  size_t                          tNodeLength,
    OUT char                            *pszServiceName,
    IN  size_t                          tServiceLength,
    IN  int                             iFlags)
/*++

Routine Description
    protocol-independent address-to-name translation.
    as specified in RFC 2553, Section 6.5.
    this is the hacked version that only supports IPv4.

Arguments
    ptSocketAddress     socket address to translate.
    tSocketLength       length of above socket address.
    pszNodeName         where to return the node name.
    tNodeLength         size of above buffer.
    pszServiceName      where to return the service name.
    tServiceLength      size of above buffer.
    iFlags              flags of type NI_*.

Return Value
    returns zero if successful, an EAI_* error code if not.

--*/
{
    struct servent  *ptService;
    WORD            wPort;
    char            szBuffer[]  = "65535";
    char            *pszService = szBuffer;

    struct hostent  *ptHost;
    struct in_addr  tAddress;
    char            *pszNode    = NULL;
    char            *pc         = NULL;


    // sanity check ptSocketAddress and tSocketLength.
    if (!ptSocketAddress)
        return EAI_FAIL;

    if ((ptSocketAddress->sa_family != AF_INET)     ||
        (tSocketLength != sizeof(struct sockaddr_in)))
    {
        return EAI_FAMILY;
    }

    if (!(pszNodeName && tNodeLength) &&
        !(pszServiceName && tServiceLength))
    {
        return EAI_NONAME;
    }

    // the draft has the "bad flags" error code, so presumably we
    // should check something here.  insisting that there aren't
    // any unspecified flags set would break forward compatibility,
    // however.  so we just check for non-sensical combinations.
    if ((iFlags & NI_NUMERICHOST) && (iFlags & NI_NAMEREQD))
    {
        return EAI_BADFLAGS;
    }

    // translate the port to a service name (if requested).
    if (pszServiceName && tServiceLength)
    {
        wPort = ((struct sockaddr_in *) ptSocketAddress)->sin_port;

        if (iFlags & NI_NUMERICSERV)
        {
            // return numeric form of the address.
            sprintf(szBuffer, "%u", ntohs(wPort));
        }
        else
        {
            // return service name corresponding to port.
            ptService = getservbyport(wPort,
                                      (iFlags & NI_DGRAM) ? "udp" : NULL);
            if (ptService && ptService->s_name)
            {
                // lookup successful.
                pszService = ptService->s_name;
            }
            else
            {
                // DRAFT: return numeric form of the port!
                sprintf(szBuffer, "%u", ntohs(wPort));
            }
        }


        if (tServiceLength > strlen(pszService))
            strcpy(pszServiceName, pszService);
        else
            return EAI_FAIL;
    }


    // translate the address to a node name (if requested).
    if (pszNodeName && tNodeLength)
    {
        // this is the IPv4-only version, so we have an IPv4 address.
        tAddress = ((struct sockaddr_in *) ptSocketAddress)->sin_addr;

        if (iFlags & NI_NUMERICHOST)
        {
            // return numeric form of the address.
            pszNode  = inet_ntoa(tAddress);
        }
        else
        {
            // return node name corresponding to address.
            ptHost = gethostbyaddr((char *) &tAddress,
                                   sizeof(struct in_addr),
                                   AF_INET);
            if (ptHost && ptHost->h_name)
            {
                // DNS lookup successful.
                // stop copying at a "." if NI_NOFQDN is specified.
                pszNode = ptHost->h_name;
                if ((iFlags & NI_NOFQDN) && (pc = strchr(pszNode, '.')))
                    *pc = '\0';
            }
            else
            {
                // DNS lookup failed.  return numeric form of the address.
                if (iFlags & NI_NAMEREQD)
                {
                    switch (WSAGetLastError())
                    {
                        case WSAHOST_NOT_FOUND: return EAI_NONAME;
                        case WSATRY_AGAIN:      return EAI_AGAIN;
                        case WSANO_RECOVERY:    return EAI_FAIL;
                        default:                return EAI_NONAME;
                    }
                }
                else
                    pszNode  = inet_ntoa(tAddress);
            }
        }

        if (tNodeLength > strlen(pszNode))
            strcpy(pszNodeName, pszNode);
        else
            return EAI_FAIL;
    }

    return 0;
}



typedef struct
{
    char const          *pszName;
    FARPROC             pfAddress;
} WSPIAPI_FUNCTION;

#define WSPIAPI_FUNCTION_ARRAY                                  \
{                                                               \
    "getaddrinfo",      (FARPROC) WspiapiLegacyGetAddrInfo,     \
    "getnameinfo",      (FARPROC) WspiapiLegacyGetNameInfo,     \
    "freeaddrinfo",     (FARPROC) WspiapiLegacyFreeAddrInfo,    \
}



__inline
FARPROC
WINAPI
WspiapiLoad(
    IN  WORD                            wFunction)
/*++

Routine Description
    try to locate the address family independent name resolution routines
    (i.e. getaddrinfo, getnameinfo, freeaddrinfo, gai_strerror).

Locks
    this function call is not synchronized.  hence the library containing
    the routines might be loaded multiple times.  another option is to
    synchronize through a spin lock using a static local variable and the
    InterlockedExchange operation.


Arguments
    wFunction           ordinal # of the function to get the pointer to
                        0   getaddrinfo
                        1   getnameinfo
                        2   freeaddrinfo

Return Value
    address of the library/legacy routine

--*/
{
    HMODULE                 hLibrary        = NULL;

    // these static variables store state across calls, across threads.
    static BOOL             bInitialized    = FALSE;
    static WSPIAPI_FUNCTION rgtGlobal[]     = WSPIAPI_FUNCTION_ARRAY;
    static const int        iNumGlobal      = (sizeof(rgtGlobal) /
                                               sizeof(WSPIAPI_FUNCTION));

    // we overwrite rgtGlobal only if all routines exist in library.
    WSPIAPI_FUNCTION        rgtLocal[]      = WSPIAPI_FUNCTION_ARRAY;
    FARPROC                 fScratch        = NULL;
    int                     i               = 0;


    if (bInitialized)           // WspiapiLoad has already been called once
        return (rgtGlobal[wFunction].pfAddress);

    do                          // breakout loop
    {
        // in Whistler and beyond...
        // the routines are present in the WinSock 2 library (ws2_32.dll).
        // printf("Looking in ws2_32 for getaddrinfo...\n");
        hLibrary = LoadLibraryA("ws2_32");
        if (hLibrary != NULL)
        {
            fScratch = GetProcAddress(hLibrary, "getaddrinfo");
            if (fScratch == NULL)
            {
                FreeLibrary(hLibrary);
                hLibrary = NULL;
            }
        }
        if (hLibrary != NULL)
            break;


        // in the IPv6 Technology Preview...
        // the routines are present in the IPv6 WinSock library (wship6.dll).
        // printf("Looking in wship6 for getaddrinfo...\n");
        hLibrary = LoadLibraryA("wship6");
        if (hLibrary != NULL)
        {
            fScratch = GetProcAddress(hLibrary, "getaddrinfo");
            if (fScratch == NULL)
            {
                FreeLibrary(hLibrary);
                hLibrary = NULL;
            }
        }
    } while (FALSE);


    if (hLibrary != NULL)
    {
        // use routines from this library...
        // since getaddrinfo is here, we expect all routines to be here,
        // but will fall back to IPv4-only if any of them is missing.
        for (i = 0; i < iNumGlobal; i++)
        {
            rgtLocal[i].pfAddress
                = GetProcAddress(hLibrary, rgtLocal[i].pszName);
            if (rgtLocal[i].pfAddress == NULL)
            {
                FreeLibrary(hLibrary);
                hLibrary = NULL;
                break;
            }
        }

        if (hLibrary != NULL)
        {
            // printf("found!\n");
            for (i = 0; i < iNumGlobal; i++)
                rgtGlobal[i].pfAddress = rgtLocal[i].pfAddress;
        }
    }

    bInitialized = TRUE;
    return (rgtGlobal[wFunction].pfAddress);
}



__inline
int
WINAPI
WspiapiGetAddrInfo(
    IN const char                       *nodename,
    IN const char                       *servname,
    IN const struct addrinfo            *hints,
    OUT struct addrinfo                 **res)
{
    static WSPIAPI_PGETADDRINFO     pfGetAddrInfo   = NULL;

    if (!pfGetAddrInfo)
        pfGetAddrInfo   = (WSPIAPI_PGETADDRINFO) WspiapiLoad(0);
    return ((*pfGetAddrInfo)
            (nodename, servname, hints, res));
}



__inline
int
WINAPI
WspiapiGetNameInfo (
    IN  const struct sockaddr           *sa,
    IN  socklen_t                       salen,
    OUT char                            *host,
    IN  size_t                          hostlen,
    OUT char                            *serv,
    IN  size_t                          servlen,
    IN  int                             flags)
{
    static WSPIAPI_PGETNAMEINFO     pfGetNameInfo   = NULL;

    if (!pfGetNameInfo)
        pfGetNameInfo   = (WSPIAPI_PGETNAMEINFO) WspiapiLoad(1);
    return ((*pfGetNameInfo)
            (sa, salen, host, hostlen, serv, servlen, flags));
}



__inline
void
WINAPI
WspiapiFreeAddrInfo (
    IN  struct addrinfo                 *ai)
{
    static WSPIAPI_PFREEADDRINFO    pfFreeAddrInfo   = NULL;

    if (!pfFreeAddrInfo)
        pfFreeAddrInfo  = (WSPIAPI_PFREEADDRINFO) WspiapiLoad(2);
    (*pfFreeAddrInfo)(ai);
}

#ifdef  __cplusplus
}
#endif

#endif // _WSPIAPI_H_