summaryrefslogtreecommitdiff
path: root/source4/heimdal/lib/krb5/krbhst.c
blob: e9111abec992cfb0215631e8dc5afd4a1b2a51d7 (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
/*
 * Copyright (c) 2001 - 2003 Kungliga Tekniska Högskolan
 * (Royal Institute of Technology, Stockholm, Sweden).
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * 3. Neither the name of the Institute nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include "krb5_locl.h"
#include <resolve.h>
#include "locate_plugin.h"

static int
string_to_proto(const char *string)
{
    if(strcasecmp(string, "udp") == 0)
	return KRB5_KRBHST_UDP;
    else if(strcasecmp(string, "tcp") == 0)
	return KRB5_KRBHST_TCP;
    else if(strcasecmp(string, "http") == 0)
	return KRB5_KRBHST_HTTP;
    return -1;
}

/*
 * set `res' and `count' to the result of looking up SRV RR in DNS for
 * `proto', `proto', `realm' using `dns_type'.
 * if `port' != 0, force that port number
 */

static krb5_error_code
srv_find_realm(krb5_context context, krb5_krbhst_info ***res, int *count,
	       const char *realm, const char *dns_type,
	       const char *proto, const char *service, int port)
{
    char domain[1024];
    struct rk_dns_reply *r;
    struct rk_resource_record *rr;
    int num_srv;
    int proto_num;
    int def_port;

    *res = NULL;
    *count = 0;

    proto_num = string_to_proto(proto);
    if(proto_num < 0) {
	krb5_set_error_message(context, EINVAL,
			       N_("unknown protocol `%s' to lookup", ""),
			       proto);
	return EINVAL;
    }

    if(proto_num == KRB5_KRBHST_HTTP)
	def_port = ntohs(krb5_getportbyname (context, "http", "tcp", 80));
    else if(port == 0)
	def_port = ntohs(krb5_getportbyname (context, service, proto, 88));
    else
	def_port = port;

    snprintf(domain, sizeof(domain), "_%s._%s.%s.", service, proto, realm);

    r = rk_dns_lookup(domain, dns_type);
    if(r == NULL)
	return KRB5_KDC_UNREACH;

    for(num_srv = 0, rr = r->head; rr; rr = rr->next)
	if(rr->type == rk_ns_t_srv)
	    num_srv++;

    *res = malloc(num_srv * sizeof(**res));
    if(*res == NULL) {
	rk_dns_free_data(r);
	krb5_set_error_message(context, ENOMEM,
			       N_("malloc: out of memory", ""));
	return ENOMEM;
    }

    rk_dns_srv_order(r);

    for(num_srv = 0, rr = r->head; rr; rr = rr->next)
	if(rr->type == rk_ns_t_srv) {
	    krb5_krbhst_info *hi;
	    size_t len = strlen(rr->u.srv->target);

	    hi = calloc(1, sizeof(*hi) + len);
	    if(hi == NULL) {
		rk_dns_free_data(r);
		while(--num_srv >= 0)
		    free((*res)[num_srv]);
		free(*res);
		*res = NULL;
		return ENOMEM;
	    }
	    (*res)[num_srv++] = hi;

	    hi->proto = proto_num;
	
	    hi->def_port = def_port;
	    if (port != 0)
		hi->port = port;
	    else
		hi->port = rr->u.srv->port;

	    strlcpy(hi->hostname, rr->u.srv->target, len + 1);
	}

    *count = num_srv;
	
    rk_dns_free_data(r);
    return 0;
}


struct krb5_krbhst_data {
    char *realm;
    unsigned int flags;
    int def_port;
    int port;			/* hardwired port number if != 0 */
#define KD_CONFIG		 1
#define KD_SRV_UDP		 2
#define KD_SRV_TCP		 4
#define KD_SRV_HTTP		 8
#define KD_FALLBACK		16
#define KD_CONFIG_EXISTS	32
#define KD_LARGE_MSG		64
#define KD_PLUGIN	       128
    krb5_error_code (*get_next)(krb5_context, struct krb5_krbhst_data *,
				krb5_krbhst_info**);

    unsigned int fallback_count;

    struct krb5_krbhst_info *hosts, **index, **end;
};

static krb5_boolean
krbhst_empty(const struct krb5_krbhst_data *kd)
{
    return kd->index == &kd->hosts;
}

/*
 * Return the default protocol for the `kd' (either TCP or UDP)
 */

static int
krbhst_get_default_proto(struct krb5_krbhst_data *kd)
{
    if (kd->flags & KD_LARGE_MSG)
	return KRB5_KRBHST_TCP;
    return KRB5_KRBHST_UDP;
}


/*
 * parse `spec' into a krb5_krbhst_info, defaulting the port to `def_port'
 * and forcing it to `port' if port != 0
 */

static struct krb5_krbhst_info*
parse_hostspec(krb5_context context, struct krb5_krbhst_data *kd,
	       const char *spec, int def_port, int port)
{
    const char *p = spec;
    struct krb5_krbhst_info *hi;

    hi = calloc(1, sizeof(*hi) + strlen(spec));
    if(hi == NULL)
	return NULL;

    hi->proto = krbhst_get_default_proto(kd);

    if(strncmp(p, "http://", 7) == 0){
	hi->proto = KRB5_KRBHST_HTTP;
	p += 7;
    } else if(strncmp(p, "http/", 5) == 0) {
	hi->proto = KRB5_KRBHST_HTTP;
	p += 5;
	def_port = ntohs(krb5_getportbyname (context, "http", "tcp", 80));
    }else if(strncmp(p, "tcp/", 4) == 0){
	hi->proto = KRB5_KRBHST_TCP;
	p += 4;
    } else if(strncmp(p, "udp/", 4) == 0) {
	p += 4;
    }

    if(strsep_copy(&p, ":", hi->hostname, strlen(spec) + 1) < 0) {
	free(hi);
	return NULL;
    }
    /* get rid of trailing /, and convert to lower case */
    hi->hostname[strcspn(hi->hostname, "/")] = '\0';
    strlwr(hi->hostname);

    hi->port = hi->def_port = def_port;
    if(p != NULL) {
	char *end;
	hi->port = strtol(p, &end, 0);
	if(end == p) {
	    free(hi);
	    return NULL;
	}
    }
    if (port)
	hi->port = port;
    return hi;
}

void
_krb5_free_krbhst_info(krb5_krbhst_info *hi)
{
    if (hi->ai != NULL)
	freeaddrinfo(hi->ai);
    free(hi);
}

krb5_error_code
_krb5_krbhost_info_move(krb5_context context,
			krb5_krbhst_info *from,
			krb5_krbhst_info **to)
{
    size_t hostnamelen = strlen(from->hostname);
    /* trailing NUL is included in structure */
    *to = calloc(1, sizeof(**to) + hostnamelen);
    if(*to == NULL) {
	krb5_set_error_message(context, ENOMEM,
			       N_("malloc: out of memory", ""));
	return ENOMEM;
    }

    (*to)->proto = from->proto;
    (*to)->port = from->port;
    (*to)->def_port = from->def_port;
    (*to)->ai = from->ai;
    from->ai = NULL;
    (*to)->next = NULL;
    memcpy((*to)->hostname, from->hostname, hostnamelen + 1);
    return 0;
}


static void
append_host_hostinfo(struct krb5_krbhst_data *kd, struct krb5_krbhst_info *host)
{
    struct krb5_krbhst_info *h;

    for(h = kd->hosts; h; h = h->next)
	if(h->proto == host->proto &&
	   h->port == host->port &&
	   strcmp(h->hostname, host->hostname) == 0) {
	    _krb5_free_krbhst_info(host);
	    return;
	}
    *kd->end = host;
    kd->end = &host->next;
}

static krb5_error_code
append_host_string(krb5_context context, struct krb5_krbhst_data *kd,
		   const char *host, int def_port, int port)
{
    struct krb5_krbhst_info *hi;

    hi = parse_hostspec(context, kd, host, def_port, port);
    if(hi == NULL)
	return ENOMEM;

    append_host_hostinfo(kd, hi);
    return 0;
}

/*
 * return a readable representation of `host' in `hostname, hostlen'
 */

krb5_error_code KRB5_LIB_FUNCTION
krb5_krbhst_format_string(krb5_context context, const krb5_krbhst_info *host,
			  char *hostname, size_t hostlen)
{
    const char *proto = "";
    char portstr[7] = "";
    if(host->proto == KRB5_KRBHST_TCP)
	proto = "tcp/";
    else if(host->proto == KRB5_KRBHST_HTTP)
	proto = "http://";
    if(host->port != host->def_port)
	snprintf(portstr, sizeof(portstr), ":%d", host->port);
    snprintf(hostname, hostlen, "%s%s%s", proto, host->hostname, portstr);
    return 0;
}

/*
 * create a getaddrinfo `hints' based on `proto'
 */

static void
make_hints(struct addrinfo *hints, int proto)
{
    memset(hints, 0, sizeof(*hints));
    hints->ai_family = AF_UNSPEC;
    switch(proto) {
    case KRB5_KRBHST_UDP :
	hints->ai_socktype = SOCK_DGRAM;
	break;
    case KRB5_KRBHST_HTTP :
    case KRB5_KRBHST_TCP :
	hints->ai_socktype = SOCK_STREAM;
	break;
    }
}

/*
 * return an `struct addrinfo *' in `ai' corresponding to the information
 * in `host'.  free:ing is handled by krb5_krbhst_free.
 */

krb5_error_code KRB5_LIB_FUNCTION
krb5_krbhst_get_addrinfo(krb5_context context, krb5_krbhst_info *host,
			 struct addrinfo **ai)
{
    struct addrinfo hints;
    char portstr[NI_MAXSERV];
    int ret;

    if (host->ai == NULL) {
	make_hints(&hints, host->proto);
	snprintf (portstr, sizeof(portstr), "%d", host->port);
	ret = getaddrinfo(host->hostname, portstr, &hints, &host->ai);
	if (ret)
	    return krb5_eai_to_heim_errno(ret, errno);
    }
    *ai = host->ai;
    return 0;
}

static krb5_boolean
get_next(struct krb5_krbhst_data *kd, krb5_krbhst_info **host)
{
    struct krb5_krbhst_info *hi = *kd->index;
    if(hi != NULL) {
	*host = hi;
	kd->index = &(*kd->index)->next;
	return TRUE;
    }
    return FALSE;
}

static void
srv_get_hosts(krb5_context context, struct krb5_krbhst_data *kd,
	      const char *proto, const char *service)
{
    krb5_krbhst_info **res;
    int count, i;

    if (srv_find_realm(context, &res, &count, kd->realm, "SRV", proto, service,
		       kd->port))
	return;
    for(i = 0; i < count; i++)
	append_host_hostinfo(kd, res[i]);
    free(res);
}

/*
 * read the configuration for `conf_string', defaulting to kd->def_port and
 * forcing it to `kd->port' if kd->port != 0
 */

static void
config_get_hosts(krb5_context context, struct krb5_krbhst_data *kd,
		 const char *conf_string)
{
    int i;
	
    char **hostlist;
    hostlist = krb5_config_get_strings(context, NULL,
				       "realms", kd->realm, conf_string, NULL);

    if(hostlist == NULL)
	return;
    kd->flags |= KD_CONFIG_EXISTS;
    for(i = 0; hostlist && hostlist[i] != NULL; i++)
	append_host_string(context, kd, hostlist[i], kd->def_port, kd->port);

    krb5_config_free_strings(hostlist);
}

/*
 * as a fallback, look for `serv_string.kd->realm' (typically
 * kerberos.REALM, kerberos-1.REALM, ...
 * `port' is the default port for the service, and `proto' the
 * protocol
 */

static krb5_error_code
fallback_get_hosts(krb5_context context, struct krb5_krbhst_data *kd,
		   const char *serv_string, int port, int proto)
{
    char *host;
    int ret;
    struct addrinfo *ai;
    struct addrinfo hints;
    char portstr[NI_MAXSERV];

    /*
     * Don't try forever in case the DNS server keep returning us
     * entries (like wildcard entries or the .nu TLD)
     */
    if(kd->fallback_count >= 5) {
	kd->flags |= KD_FALLBACK;
	return 0;
    }

    if(kd->fallback_count == 0)
	asprintf(&host, "%s.%s.", serv_string, kd->realm);
    else
	asprintf(&host, "%s-%d.%s.",
		 serv_string, kd->fallback_count, kd->realm);	

    if (host == NULL)
	return ENOMEM;

    make_hints(&hints, proto);
    snprintf(portstr, sizeof(portstr), "%d", port);
    ret = getaddrinfo(host, portstr, &hints, &ai);
    if (ret) {
	/* no more hosts, so we're done here */
	free(host);
	kd->flags |= KD_FALLBACK;
    } else {
	struct krb5_krbhst_info *hi;
	size_t hostlen = strlen(host);

	hi = calloc(1, sizeof(*hi) + hostlen);
	if(hi == NULL) {
	    free(host);
	    return ENOMEM;
	}

	hi->proto = proto;
	hi->port  = hi->def_port = port;
	hi->ai    = ai;
	memmove(hi->hostname, host, hostlen);
	hi->hostname[hostlen] = '\0';
	free(host);
	append_host_hostinfo(kd, hi);
	kd->fallback_count++;
    }
    return 0;
}

/*
 * Fetch hosts from plugin
 */

static krb5_error_code
add_locate(void *ctx, int type, struct sockaddr *addr)
{
    struct krb5_krbhst_info *hi;
    struct krb5_krbhst_data *kd = ctx;
    char host[NI_MAXHOST], port[NI_MAXSERV];
    struct addrinfo hints, *ai;
    socklen_t socklen;
    size_t hostlen;
    int ret;

    socklen = socket_sockaddr_size(addr);

    ret = getnameinfo(addr, socklen, host, sizeof(host), port, sizeof(port),
		      NI_NUMERICHOST|NI_NUMERICSERV);
    if (ret != 0)
	return 0;

    make_hints(&hints, krbhst_get_default_proto(kd));
    ret = getaddrinfo(host, port, &hints, &ai);
    if (ret)
	return 0;

    hostlen = strlen(host);

    hi = calloc(1, sizeof(*hi) + hostlen);
    if(hi == NULL)
	return ENOMEM;

    hi->proto = krbhst_get_default_proto(kd);
    hi->port  = hi->def_port = socket_get_port(addr);
    hi->ai    = ai;
    memmove(hi->hostname, host, hostlen);
    hi->hostname[hostlen] = '\0';
    append_host_hostinfo(kd, hi);

    return 0;
}

static void
plugin_get_hosts(krb5_context context,
		 struct krb5_krbhst_data *kd,
		 enum locate_service_type type)
{
    struct krb5_plugin *list = NULL, *e;
    krb5_error_code ret;

    ret = _krb5_plugin_find(context, PLUGIN_TYPE_DATA,
			    KRB5_PLUGIN_LOCATE, &list);
    if(ret != 0 || list == NULL)
	return;

    for (e = list; e != NULL; e = _krb5_plugin_get_next(e)) {
	krb5plugin_service_locate_ftable *service;
	void *ctx;

	service = _krb5_plugin_get_symbol(e);
	if (service->minor_version != 0)
	    continue;
	
	(*service->init)(context, &ctx);
	ret = (*service->lookup)(ctx, type, kd->realm, 0, 0, add_locate, kd);
	(*service->fini)(ctx);
	if (ret && ret != KRB5_PLUGIN_NO_HANDLE) {
	    krb5_set_error_message(context, ret,
				   N_("Locate plugin failed to lookup realm %s: %d", ""),
				   kd->realm, ret);
	    break;
	} else if (ret == 0)
	    kd->flags |= KD_CONFIG_EXISTS;

    }
    _krb5_plugin_free(list);
}

/*
 *
 */

static krb5_error_code
kdc_get_next(krb5_context context,
	     struct krb5_krbhst_data *kd,
	     krb5_krbhst_info **host)
{
    krb5_error_code ret;

    if ((kd->flags & KD_PLUGIN) == 0) {
	plugin_get_hosts(context, kd, locate_service_kdc);
	kd->flags |= KD_PLUGIN;
	if(get_next(kd, host))
	    return 0;
    }

    if((kd->flags & KD_CONFIG) == 0) {
	config_get_hosts(context, kd, "kdc");
	kd->flags |= KD_CONFIG;
	if(get_next(kd, host))
	    return 0;
    }

    if (kd->flags & KD_CONFIG_EXISTS)
	return KRB5_KDC_UNREACH; /* XXX */

    if(context->srv_lookup) {
	if((kd->flags & KD_SRV_UDP) == 0 && (kd->flags & KD_LARGE_MSG) == 0) {
	    srv_get_hosts(context, kd, "udp", "kerberos");
	    kd->flags |= KD_SRV_UDP;
	    if(get_next(kd, host))
		return 0;
	}

	if((kd->flags & KD_SRV_TCP) == 0) {
	    srv_get_hosts(context, kd, "tcp", "kerberos");
	    kd->flags |= KD_SRV_TCP;
	    if(get_next(kd, host))
		return 0;
	}
	if((kd->flags & KD_SRV_HTTP) == 0) {
	    srv_get_hosts(context, kd, "http", "kerberos");
	    kd->flags |= KD_SRV_HTTP;
	    if(get_next(kd, host))
		return 0;
	}
    }

    while((kd->flags & KD_FALLBACK) == 0) {
	ret = fallback_get_hosts(context, kd, "kerberos",
				 kd->def_port,
				 krbhst_get_default_proto(kd));
	if(ret)
	    return ret;
	if(get_next(kd, host))
	    return 0;
    }

    return KRB5_KDC_UNREACH; /* XXX */
}

static krb5_error_code
admin_get_next(krb5_context context,
	       struct krb5_krbhst_data *kd,
	       krb5_krbhst_info **host)
{
    krb5_error_code ret;

    if ((kd->flags & KD_PLUGIN) == 0) {
	plugin_get_hosts(context, kd, locate_service_kadmin);
	kd->flags |= KD_PLUGIN;
	if(get_next(kd, host))
	    return 0;
    }

    if((kd->flags & KD_CONFIG) == 0) {
	config_get_hosts(context, kd, "admin_server");
	kd->flags |= KD_CONFIG;
	if(get_next(kd, host))
	    return 0;
    }

    if (kd->flags & KD_CONFIG_EXISTS)
	return KRB5_KDC_UNREACH; /* XXX */

    if(context->srv_lookup) {
	if((kd->flags & KD_SRV_TCP) == 0) {
	    srv_get_hosts(context, kd, "tcp", "kerberos-adm");
	    kd->flags |= KD_SRV_TCP;
	    if(get_next(kd, host))
		return 0;
	}
    }

    if (krbhst_empty(kd)
	&& (kd->flags & KD_FALLBACK) == 0) {
	ret = fallback_get_hosts(context, kd, "kerberos",
				 kd->def_port,
				 krbhst_get_default_proto(kd));
	if(ret)
	    return ret;
	kd->flags |= KD_FALLBACK;
	if(get_next(kd, host))
	    return 0;
    }

    return KRB5_KDC_UNREACH;	/* XXX */
}

static krb5_error_code
kpasswd_get_next(krb5_context context,
		 struct krb5_krbhst_data *kd,
		 krb5_krbhst_info **host)
{
    krb5_error_code ret;

    if ((kd->flags & KD_PLUGIN) == 0) {
	plugin_get_hosts(context, kd, locate_service_kpasswd);
	kd->flags |= KD_PLUGIN;
	if(get_next(kd, host))
	    return 0;
    }

    if((kd->flags & KD_CONFIG) == 0) {
	config_get_hosts(context, kd, "kpasswd_server");
	kd->flags |= KD_CONFIG;
	if(get_next(kd, host))
	    return 0;
    }

    if (kd->flags & KD_CONFIG_EXISTS)
	return KRB5_KDC_UNREACH; /* XXX */

    if(context->srv_lookup) {
	if((kd->flags & KD_SRV_UDP) == 0) {
	    srv_get_hosts(context, kd, "udp", "kpasswd");
	    kd->flags |= KD_SRV_UDP;
	    if(get_next(kd, host))
		return 0;
	}
	if((kd->flags & KD_SRV_TCP) == 0) {
	    srv_get_hosts(context, kd, "tcp", "kpasswd");
	    kd->flags |= KD_SRV_TCP;
	    if(get_next(kd, host))
		return 0;
	}
    }

    /* no matches -> try admin */

    if (krbhst_empty(kd)) {
	kd->flags = 0;
	kd->port  = kd->def_port;
	kd->get_next = admin_get_next;
	ret = (*kd->get_next)(context, kd, host);
	if (ret == 0)
	    (*host)->proto = krbhst_get_default_proto(kd);
	return ret;
    }

    return KRB5_KDC_UNREACH; /* XXX */
}

static krb5_error_code
krb524_get_next(krb5_context context,
		struct krb5_krbhst_data *kd,
		krb5_krbhst_info **host)
{
    if ((kd->flags & KD_PLUGIN) == 0) {
	plugin_get_hosts(context, kd, locate_service_krb524);
	kd->flags |= KD_PLUGIN;
	if(get_next(kd, host))
	    return 0;
    }

    if((kd->flags & KD_CONFIG) == 0) {
	config_get_hosts(context, kd, "krb524_server");
	if(get_next(kd, host))
	    return 0;
	kd->flags |= KD_CONFIG;
    }

    if (kd->flags & KD_CONFIG_EXISTS)
	return KRB5_KDC_UNREACH; /* XXX */

    if(context->srv_lookup) {
	if((kd->flags & KD_SRV_UDP) == 0) {
	    srv_get_hosts(context, kd, "udp", "krb524");
	    kd->flags |= KD_SRV_UDP;
	    if(get_next(kd, host))
		return 0;
	}

	if((kd->flags & KD_SRV_TCP) == 0) {
	    srv_get_hosts(context, kd, "tcp", "krb524");
	    kd->flags |= KD_SRV_TCP;
	    if(get_next(kd, host))
		return 0;
	}
    }

    /* no matches -> try kdc */

    if (krbhst_empty(kd)) {
	kd->flags = 0;
	kd->port  = kd->def_port;
	kd->get_next = kdc_get_next;
	return (*kd->get_next)(context, kd, host);
    }

    return KRB5_KDC_UNREACH; /* XXX */
}

static struct krb5_krbhst_data*
common_init(krb5_context context,
	    const char *realm,
	    int flags)
{
    struct krb5_krbhst_data *kd;

    if((kd = calloc(1, sizeof(*kd))) == NULL)
	return NULL;

    if((kd->realm = strdup(realm)) == NULL) {
	free(kd);
	return NULL;
    }

    /* For 'realms' without a . do not even think of going to DNS */
    if (!strchr(realm, '.'))
	kd->flags |= KD_CONFIG_EXISTS;

    if (flags & KRB5_KRBHST_FLAGS_LARGE_MSG)
	kd->flags |= KD_LARGE_MSG;
    kd->end = kd->index = &kd->hosts;
    return kd;
}

/*
 * initialize `handle' to look for hosts of type `type' in realm `realm'
 */

krb5_error_code KRB5_LIB_FUNCTION
krb5_krbhst_init(krb5_context context,
		 const char *realm,
		 unsigned int type,
		 krb5_krbhst_handle *handle)
{
    return krb5_krbhst_init_flags(context, realm, type, 0, handle);
}

krb5_error_code KRB5_LIB_FUNCTION
krb5_krbhst_init_flags(krb5_context context,
		       const char *realm,
		       unsigned int type,
		       int flags,
		       krb5_krbhst_handle *handle)
{
    struct krb5_krbhst_data *kd;
    krb5_error_code (*next)(krb5_context, struct krb5_krbhst_data *,
			    krb5_krbhst_info **);
    int def_port;

    switch(type) {
    case KRB5_KRBHST_KDC:
	next = kdc_get_next;
	def_port = ntohs(krb5_getportbyname (context, "kerberos", "udp", 88));
	break;
    case KRB5_KRBHST_ADMIN:
	next = admin_get_next;
	def_port = ntohs(krb5_getportbyname (context, "kerberos-adm",
					     "tcp", 749));
	break;
    case KRB5_KRBHST_CHANGEPW:
	next = kpasswd_get_next;
	def_port = ntohs(krb5_getportbyname (context, "kpasswd", "udp",
					     KPASSWD_PORT));
	break;
    case KRB5_KRBHST_KRB524:
	next = krb524_get_next;
	def_port = ntohs(krb5_getportbyname (context, "krb524", "udp", 4444));
	break;
    default:
	krb5_set_error_message(context, ENOTTY,
			       N_("unknown krbhst type (%u)", ""), type);
	return ENOTTY;
    }
    if((kd = common_init(context, realm, flags)) == NULL)
	return ENOMEM;
    kd->get_next = next;
    kd->def_port = def_port;
    *handle = kd;
    return 0;
}

/*
 * return the next host information from `handle' in `host'
 */

krb5_error_code KRB5_LIB_FUNCTION
krb5_krbhst_next(krb5_context context,
		 krb5_krbhst_handle handle,
		 krb5_krbhst_info **host)
{
    if(get_next(handle, host))
	return 0;

    return (*handle->get_next)(context, handle, host);
}

/*
 * return the next host information from `handle' as a host name
 * in `hostname' (or length `hostlen)
 */

krb5_error_code KRB5_LIB_FUNCTION
krb5_krbhst_next_as_string(krb5_context context,
			   krb5_krbhst_handle handle,
			   char *hostname,
			   size_t hostlen)
{
    krb5_error_code ret;
    krb5_krbhst_info *host;
    ret = krb5_krbhst_next(context, handle, &host);
    if(ret)
	return ret;
    return krb5_krbhst_format_string(context, host, hostname, hostlen);
}


void KRB5_LIB_FUNCTION
krb5_krbhst_reset(krb5_context context, krb5_krbhst_handle handle)
{
    handle->index = &handle->hosts;
}

void KRB5_LIB_FUNCTION
krb5_krbhst_free(krb5_context context, krb5_krbhst_handle handle)
{
    krb5_krbhst_info *h, *next;

    if (handle == NULL)
	return;

    for (h = handle->hosts; h != NULL; h = next) {
	next = h->next;
	_krb5_free_krbhst_info(h);
    }

    free(handle->realm);
    free(handle);
}

/* backwards compatibility ahead */

static krb5_error_code
gethostlist(krb5_context context, const char *realm,
	    unsigned int type, char ***hostlist)
{
    krb5_error_code ret;
    int nhost = 0;
    krb5_krbhst_handle handle;
    char host[MAXHOSTNAMELEN];
    krb5_krbhst_info *hostinfo;

    ret = krb5_krbhst_init(context, realm, type, &handle);
    if (ret)
	return ret;

    while(krb5_krbhst_next(context, handle, &hostinfo) == 0)
	nhost++;
    if(nhost == 0) {
	krb5_set_error_message(context, KRB5_KDC_UNREACH,
			       N_("No KDC found for realm %s", ""), realm);
	return KRB5_KDC_UNREACH;
    }
    *hostlist = calloc(nhost + 1, sizeof(**hostlist));
    if(*hostlist == NULL) {
	krb5_krbhst_free(context, handle);
	return ENOMEM;
    }

    krb5_krbhst_reset(context, handle);
    nhost = 0;
    while(krb5_krbhst_next_as_string(context, handle,
				     host, sizeof(host)) == 0) {
	if(((*hostlist)[nhost++] = strdup(host)) == NULL) {
	    krb5_free_krbhst(context, *hostlist);
	    krb5_krbhst_free(context, handle);
	    return ENOMEM;
	}
    }
    (*hostlist)[nhost] = NULL;
    krb5_krbhst_free(context, handle);
    return 0;
}

/*
 * return an malloced list of kadmin-hosts for `realm' in `hostlist'
 */

krb5_error_code KRB5_LIB_FUNCTION
krb5_get_krb_admin_hst (krb5_context context,
			const krb5_realm *realm,
			char ***hostlist)
{
    return gethostlist(context, *realm, KRB5_KRBHST_ADMIN, hostlist);
}

/*
 * return an malloced list of changepw-hosts for `realm' in `hostlist'
 */

krb5_error_code KRB5_LIB_FUNCTION
krb5_get_krb_changepw_hst (krb5_context context,
			   const krb5_realm *realm,
			   char ***hostlist)
{
    return gethostlist(context, *realm, KRB5_KRBHST_CHANGEPW, hostlist);
}

/*
 * return an malloced list of 524-hosts for `realm' in `hostlist'
 */

krb5_error_code KRB5_LIB_FUNCTION
krb5_get_krb524hst (krb5_context context,
		    const krb5_realm *realm,
		    char ***hostlist)
{
    return gethostlist(context, *realm, KRB5_KRBHST_KRB524, hostlist);
}


/*
 * return an malloced list of KDC's for `realm' in `hostlist'
 */

krb5_error_code KRB5_LIB_FUNCTION
krb5_get_krbhst (krb5_context context,
		 const krb5_realm *realm,
		 char ***hostlist)
{
    return gethostlist(context, *realm, KRB5_KRBHST_KDC, hostlist);
}

/*
 * free all the memory allocated in `hostlist'
 */

krb5_error_code KRB5_LIB_FUNCTION
krb5_free_krbhst (krb5_context context,
		  char **hostlist)
{
    char **p;

    for (p = hostlist; *p; ++p)
	free (*p);
    free (hostlist);
    return 0;
}