summaryrefslogtreecommitdiff
path: root/libc/inet/resolv.c
blob: 38aa9b272f462f6ce29f3a88799323794c032219 (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
/* resolv.c: DNS Resolver
 *
 * Copyright (C) 1998  Kenneth Albanowski <kjahds@kjahds.com>,
 *                     The Silver Hammer Group, Ltd.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 *  5-Oct-2000 W. Greathouse  wgreathouse@smva.com
 *                              Fix memory leak and memory corruption.
 *                              -- Every name resolution resulted in
 *                                 a new parse of resolv.conf and new
 *                                 copy of nameservers allocated by
 *                                 strdup.
 *                              -- Every name resolution resulted in
 *                                 a new read of resolv.conf without
 *                                 resetting index from prior read...
 *                                 resulting in exceeding array bounds.
 *
 *                              Limit nameservers read from resolv.conf
 *
 *                              Add "search" domains from resolv.conf
 *
 *                              Some systems will return a security
 *                              signature along with query answer for
 *                              dynamic DNS entries.
 *                              -- skip/ignore this answer
 *
 *                              Include arpa/nameser.h for defines.
 *
 *                              General cleanup
 *
 */

#define __FORCE_GLIBC__
#include <features.h>
#include <string.h>
#include <stdio.h>
#include <signal.h>
#include <errno.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdlib.h>
#include <unistd.h>
#include <cfgfile.h>
#include <resolv.h>
#include <netdb.h>
#include <arpa/nameser.h>

#define MAX_RECURSE 5
#define REPLY_TIMEOUT 10
#define MAX_RETRIES 15
#define MAX_SERVERS 3
#define MAX_SEARCH 4

#undef DEBUG
#ifdef DEBUG
static inline void DPRINTF(const char *format, ...)
{
	va_list args;
	va_start(args, format);
	vfprintf(stderr, format, args);
	va_end(args);
}
#else
static inline void DPRINTF(const char *format, ...) { }
#endif

#ifdef L_encodeh
int encode_header(struct resolv_header *h, unsigned char *dest, int maxlen)
{
	if (maxlen < HFIXEDSZ)
		return -1;

	dest[0] = (h->id & 0xff00) >> 8;
	dest[1] = (h->id & 0x00ff) >> 0;
	dest[2] = (h->qr ? 0x80 : 0) |
		((h->opcode & 0x0f) << 3) |
		(h->aa ? 0x04 : 0) | 
		(h->tc ? 0x02 : 0) | 
		(h->rd ? 0x01 : 0);
	dest[3] = (h->ra ? 0x80 : 0) | (h->rcode & 0x0f);
	dest[4] = (h->qdcount & 0xff00) >> 8;
	dest[5] = (h->qdcount & 0x00ff) >> 0;
	dest[6] = (h->ancount & 0xff00) >> 8;
	dest[7] = (h->ancount & 0x00ff) >> 0;
	dest[8] = (h->nscount & 0xff00) >> 8;
	dest[9] = (h->nscount & 0x00ff) >> 0;
	dest[10] = (h->arcount & 0xff00) >> 8;
	dest[11] = (h->arcount & 0x00ff) >> 0;

	return HFIXEDSZ;
}
#endif

#ifdef L_decodeh
int decode_header(unsigned char *data, struct resolv_header *h)
{
	h->id = (data[0] << 8) | data[1];
	h->qr = (data[2] & 0x80) ? 1 : 0;
	h->opcode = (data[2] >> 3) & 0x0f;
	h->aa = (data[2] & 0x04) ? 1 : 0;
	h->tc = (data[2] & 0x02) ? 1 : 0;
	h->rd = (data[2] & 0x01) ? 1 : 0;
	h->ra = (data[3] & 0x80) ? 1 : 0;
	h->rcode = data[3] & 0x0f;
	h->qdcount = (data[4] << 8) | data[5];
	h->ancount = (data[6] << 8) | data[7];
	h->nscount = (data[8] << 8) | data[9];
	h->arcount = (data[10] << 8) | data[11];

	return HFIXEDSZ;
}
#endif

#ifdef L_encoded
/* Encode a dotted string into nameserver transport-level encoding.
   This routine is fairly dumb, and doesn't attempt to compress
   the data */

int encode_dotted(const char *dotted, unsigned char *dest, int maxlen)
{
	int used = 0;

	while (dotted && *dotted) {
		char *c = strchr(dotted, '.');
		int l = c ? c - dotted : strlen(dotted);

		if (l >= (maxlen - used - 1))
			return -1;

		dest[used++] = l;
		memcpy(dest + used, dotted, l);
		used += l;

		if (c)
			dotted = c + 1;
		else
			break;
	}

	if (maxlen < 1)
		return -1;

	dest[used++] = 0;

	return used;
}
#endif

#ifdef L_decoded
/* Decode a dotted string from nameserver transport-level encoding.
   This routine understands compressed data. */

int decode_dotted(const unsigned char *data, int offset,
				  char *dest, int maxlen)
{
	int l;
	int measure = 1;
	int total = 0;
	int used = 0;

	if (!data)
		return -1;

	while ((l=data[offset++])) {
		if (measure)
		    total++;
		if ((l & 0xc0) == (0xc0)) {
			if (measure)
				total++;
			/* compressed item, redirect */
			offset = ((l & 0x3f) << 8) | data[offset];
			measure = 0;
			continue;
		}

		if ((used + l + 1) >= maxlen)
			return -1;

		memcpy(dest + used, data + offset, l);
		offset += l;
		used += l;
		if (measure)
			total += l;

		if (data[offset] != 0)
			dest[used++] = '.';
		else
			dest[used++] = '\0';
	}

	DPRINTF("Total decode len = %d\n", total);

	return total;
}
#endif

#ifdef L_lengthd

int length_dotted(const unsigned char *data, int offset)
{
	int orig_offset = offset;
	int l;

	if (!data)
		return -1;

	while ((l = data[offset++])) {

		if ((l & 0xc0) == (0xc0)) {
			offset++;
			break;
		}

		offset += l;
	}

	return offset - orig_offset;
}
#endif

#ifdef L_encodeq
int encode_question(struct resolv_question *q,
					unsigned char *dest, int maxlen)
{
	int i;

	i = encode_dotted(q->dotted, dest, maxlen);
	if (i < 0)
		return i;

	dest += i;
	maxlen -= i;

	if (maxlen < 4)
		return -1;

	dest[0] = (q->qtype & 0xff00) >> 8;
	dest[1] = (q->qtype & 0x00ff) >> 0;
	dest[2] = (q->qclass & 0xff00) >> 8;
	dest[3] = (q->qclass & 0x00ff) >> 0;

	return i + 4;
}
#endif

#ifdef L_decodeq
int decode_question(unsigned char *message, int offset,
					struct resolv_question *q)
{
	char temp[256];
	int i;

	i = decode_dotted(message, offset, temp, sizeof(temp));
	if (i < 0)
		return i;

	offset += i;

	q->dotted = strdup(temp);
	q->qtype = (message[offset + 0] << 8) | message[offset + 1];
	q->qclass = (message[offset + 2] << 8) | message[offset + 3];

	return i + 4;
}
#endif

#ifdef L_lengthq
int length_question(unsigned char *message, int offset)
{
	int i;

	i = length_dotted(message, offset);
	if (i < 0)
		return i;

	return i + 4;
}
#endif

#ifdef L_encodea
int encode_answer(struct resolv_answer *a, unsigned char *dest, int maxlen)
{
	int i;

	i = encode_dotted(a->dotted, dest, maxlen);
	if (i < 0)
		return i;

	dest += i;
	maxlen -= i;

	if (maxlen < (RRFIXEDSZ+a->rdlength))
		return -1;

	*dest++ = (a->atype & 0xff00) >> 8;
	*dest++ = (a->atype & 0x00ff) >> 0;
	*dest++ = (a->aclass & 0xff00) >> 8;
	*dest++ = (a->aclass & 0x00ff) >> 0;
	*dest++ = (a->ttl & 0xff000000) >> 24;
	*dest++ = (a->ttl & 0x00ff0000) >> 16;
	*dest++ = (a->ttl & 0x0000ff00) >> 8;
	*dest++ = (a->ttl & 0x000000ff) >> 0;
	*dest++ = (a->rdlength & 0xff00) >> 8;
	*dest++ = (a->rdlength & 0x00ff) >> 0;
	memcpy(dest, a->rdata, a->rdlength);

	return i + RRFIXEDSZ + a->rdlength;
}
#endif

#ifdef L_decodea
int decode_answer(unsigned char *message, int offset,
				  struct resolv_answer *a)
{
	char temp[256];
	int i;

	i = decode_dotted(message, offset, temp, sizeof(temp));
	if (i < 0)
		return i;

	message += offset + i;

	a->dotted = strdup(temp);
	a->atype = (message[0] << 8) | message[1];
	message += 2;
	a->aclass = (message[0] << 8) | message[1];
	message += 2;
	a->ttl = (message[0] << 24) |
		(message[1] << 16) | (message[2] << 8) | (message[3] << 0);
	message += 4;
	a->rdlength = (message[0] << 8) | message[1];
	message += 2;
	a->rdata = message;
	a->rdoffset = offset + i + RRFIXEDSZ;

	DPRINTF("i=%d,rdlength=%d\n", i, a->rdlength);

	return i + RRFIXEDSZ + a->rdlength;
}
#endif

#ifdef L_encodep
int encode_packet(struct resolv_header *h,
	struct resolv_question **q,
	struct resolv_answer **an,
	struct resolv_answer **ns,
	struct resolv_answer **ar,
	unsigned char *dest, int maxlen)
{
	int i, total = 0;
	int j;

	i = encode_header(h, dest, maxlen);
	if (i < 0)
		return i;

	dest += i;
	maxlen -= i;
	total += i;

	for (j = 0; j < h->qdcount; j++) {
		i = encode_question(q[j], dest, maxlen);
		if (i < 0)
			return i;
		dest += i;
		maxlen -= i;
		total += i;
	}

	for (j = 0; j < h->ancount; j++) {
		i = encode_answer(an[j], dest, maxlen);
		if (i < 0)
			return i;
		dest += i;
		maxlen -= i;
		total += i;
	}
	for (j = 0; j < h->nscount; j++) {
		i = encode_answer(ns[j], dest, maxlen);
		if (i < 0)
			return i;
		dest += i;
		maxlen -= i;
		total += i;
	}
	for (j = 0; j < h->arcount; j++) {
		i = encode_answer(ar[j], dest, maxlen);
		if (i < 0)
			return i;
		dest += i;
		maxlen -= i;
		total += i;
	}

	return total;
}
#endif

#ifdef L_decodep
int decode_packet(unsigned char *data, struct resolv_header *h)
{
	return decode_header(data, h);
}
#endif

#ifdef L_formquery
int form_query(int id, const char *name, int type, unsigned char *packet,
			   int maxlen)
{
	struct resolv_header h;
	struct resolv_question q;
	int i, j;

	memset(&h, 0, sizeof(h));
	h.id = id;
	h.qdcount = 1;

	q.dotted = (char *) name;
	q.qtype = type;
	q.qclass = C_IN; /* CLASS_IN */

	i = encode_header(&h, packet, maxlen);
	if (i < 0)
		return i;

	j = encode_question(&q, packet + i, maxlen - i);
	if (j < 0)
		return j;

	return i + j;
}
#endif

#ifdef L_dnslookup

int dns_caught_signal = 0;
void dns_catch_signal(int signo)
{
	dns_caught_signal = 1;
}

int dns_lookup(const char *name, int type, int nscount, const char **nsip,
			   unsigned char **outpacket, struct resolv_answer *a)
{
	static int id = 1;
	int i, j, len, fd, pos;
	static int ns = 0;
	struct sockaddr_in sa;
	int oldalarm;
	__sighandler_t oldhandler;
	struct resolv_header h;
	struct resolv_question q;
	int retries = 0;
	unsigned char * packet = malloc(PACKETSZ);
	unsigned char * lookup = malloc(MAXDNAME);
	int variant = 0;
	extern int searchdomains;
	extern const char * searchdomain[MAX_SEARCH];

	fd = -1;

	if (!packet || !lookup || !nscount)
	    goto fail;

	DPRINTF("Looking up type %d answer for '%s'\n", type, name);

	ns %= nscount;

	while (retries++ < MAX_RETRIES) {

		if (fd != -1)
			close(fd);

		fd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);

		if (fd == -1)
			goto fail;

		memset(packet, 0, PACKETSZ);

		memset(&h, 0, sizeof(h));
		h.id = ++id;
		h.qdcount = 1;
		h.rd = 1;

		DPRINTF("encoding header\n", h.rd);

		i = encode_header(&h, packet, PACKETSZ);
		if (i < 0)
			goto fail;

		strncpy(lookup,name,MAXDNAME);
		if (variant < searchdomains && strchr(lookup, '.') == NULL)
		{
		    strncat(lookup,".", MAXDNAME);
		    strncat(lookup,searchdomain[variant], MAXDNAME);
		}
		DPRINTF("lookup name: %s\n", lookup);
		q.dotted = (char *)lookup;
		q.qtype = type;
		q.qclass = C_IN; /* CLASS_IN */

		j = encode_question(&q, packet+i, PACKETSZ-i);
		if (j < 0)
			goto fail;

		len = i + j;

		DPRINTF("On try %d, sending query to port %d of machine %s\n",
				retries, NAMESERVER_PORT, nsip[ns]);

		sa.sin_family = AF_INET;
		sa.sin_port = htons(NAMESERVER_PORT);
		sa.sin_addr.s_addr = inet_addr(nsip[ns]);

		if (connect(fd, (struct sockaddr *) &sa, sizeof(sa)) == -1) {
			if (errno == ENETUNREACH) {
				/* routing error, presume not transient */
				goto tryall;
			} else
				/* retry */
				continue;
		}

		DPRINTF("Transmitting packet of length %d, id=%d, qr=%d\n",
				len, h.id, h.qr);

		send(fd, packet, len, 0);

		dns_caught_signal = 0;
		oldalarm = alarm(REPLY_TIMEOUT);
		oldhandler = signal(SIGALRM, dns_catch_signal);

		i = recv(fd, packet, PACKETSZ, 0);

		alarm(0);
		signal(SIGALRM, oldhandler);
		alarm(oldalarm);

		DPRINTF("Timeout=%d, len=%d\n", dns_caught_signal, i);

		if (dns_caught_signal)
			/* timed out, so retry send and receive,
			   to next nameserver on queue */
			goto again;

		if (i < HFIXEDSZ)
			/* too short ! */
			goto again;

		decode_header(packet, &h);

		DPRINTF("id = %d, qr = %d\n", h.id, h.qr);

		if ((h.id != id) || (!h.qr))
			/* unsolicited */
			goto again;

		DPRINTF("Got response %s\n", "(i think)!");
		DPRINTF("qrcount=%d,ancount=%d,nscount=%d,arcount=%d\n",
				h.qdcount, h.ancount, h.nscount, h.arcount);
		DPRINTF("opcode=%d,aa=%d,tc=%d,rd=%d,ra=%d,rcode=%d\n",
				h.opcode, h.aa, h.tc, h.rd, h.ra, h.rcode);

		if ((h.rcode) || (h.ancount < 1)) {
			/* negative result, not present */
			goto again;
		}

		pos = HFIXEDSZ;

		for (j = 0; j < h.qdcount; j++) {
			DPRINTF("Skipping question %d at %d\n", j, pos);
			i = length_question(packet, pos);
			DPRINTF("Length of question %d is %d\n", j, i);
			if (i < 0)
				goto again;
			pos += i;
		}
		DPRINTF("Decoding answer at pos %d\n", pos);

		for (j=0;j<h.ancount;j++)
		{
		    i = decode_answer(packet, pos, a);

		    if (i<0) {
			DPRINTF("failed decode %d\n", i);
			goto again;
		    }
		    /* For all but T_SIG, accept first answer */
		    if (a->atype != T_SIG)
			break;

		    DPRINTF("skipping T_SIG %d\n", i);
		    free(a->dotted);
		    pos += i;
		}

		DPRINTF("Answer name = |%s|\n", a->dotted);
		DPRINTF("Answer type = |%d|\n", a->atype);

		close(fd);

		if (outpacket)
			*outpacket = packet;
		else
			free(packet);
		return (0);				/* success! */

	  tryall:
		/* if there are other nameservers, give them a go,
		   otherwise return with error */
		variant = 0;
		if (retries >= nscount*(searchdomains+1))
		    goto fail;

	  again:
		/* if there are searchdomains, try them or fallback as passed */
		if (variant < searchdomains) {
		    /* next search */
		    variant++;
		} else {
		    /* next server, first search */
		    ns = (ns + 1) % nscount;
		    variant = 0;
		}
	}

fail:
	if (fd != -1)
	    close(fd);
	if (lookup)
	    free(lookup);
	if (packet)
	    free(packet);
	return -1;
}
#endif

#ifdef L_resolveaddress

int resolve_address(const char *address, int nscount, 
	const char **nsip, struct in_addr *in)
{
	unsigned char *packet;
	struct resolv_answer a;
	char temp[256];
	int i;
	int nest = 0;

	if (!address || !in)
		return -1;

	strncpy(temp, address, sizeof(temp));

	for (;;) {

		i = dns_lookup(temp, T_A, nscount, nsip, &packet, &a);

		if (i < 0)
			return -1;

		free(a.dotted);

		if (a.atype == T_CNAME) {		/* CNAME */
			DPRINTF("Got a CNAME in resolve_address()\n");
			i = decode_dotted(packet, a.rdoffset, temp, sizeof(temp));
			free(packet);

			if (i < 0)
				return -1;
			if (++nest > MAX_RECURSE)
				return -1;
			continue;
		} else if (a.atype == T_A) {	/* ADDRESS */
			free(packet);
			break;
		} else {
			free(packet);
			return -1;
		}
	}

	if (in)
	    memcpy(in, a.rdata, INADDRSZ); /* IPv4 T_A */

	return 0;
}
#endif

#ifdef L_resolvemailbox

int resolve_mailbox(const char *address,
					int nscount, const char **nsip, struct in_addr *in)
{
	struct resolv_answer a;
	unsigned char *packet;
	char temp[256];
	int nest = 0;
	int i;

	if (!address || !in)
		return -1;

	/* look up mail exchange */
	i = dns_lookup(address, T_MX, nscount, nsip, &packet, &a);

	strncpy(temp, address, sizeof(temp));

	if (i >= 0) {
		i = decode_dotted(packet, a.rdoffset+2, temp, sizeof(temp));
		free(packet);
	}

	for (;;) {

		i = dns_lookup(temp, T_A, nscount, nsip, &packet, &a);

		if (i < 0)
			return -1;

		free(a.dotted);

		if (a.atype == T_CNAME) {		/* CNAME */
			DPRINTF("Got a CNAME in resolve_mailbox()\n");
			i = decode_dotted(packet, a.rdoffset, temp, sizeof(temp));
			free(packet);
			if (i < 0)
				return i;
			if (++nest > MAX_RECURSE)
				return -1;
			continue;
		} else if (a.atype == T_A) {	/* ADDRESS */
			free(packet);
			break;
		} else {
			free(packet);
			return -1;
		}
	}

	if (in)
		memcpy(in, a.rdata, INADDRSZ); /* IPv4 */

	return 0;
}
#endif

extern int nameservers;
extern const char * nameserver[MAX_SERVERS];
extern int searchdomains;
extern const char * searchdomain[MAX_SEARCH];

#ifdef L_opennameservers

int nameservers;
const char * nameserver[MAX_SERVERS];
int searchdomains;
const char * searchdomain[MAX_SEARCH];

int open_nameservers()
{
	FILE *fp;
	char **arg;
	int i;

	if (nameservers > 0) 
	    return 0;

	if ((fp = fopen("/etc/resolv.conf", "r"))) {
		if (0 != (arg = cfgfind(fp, "nameserver"))) {
			for (i=1; arg[i] && nameservers <= MAX_SERVERS; i++) {
				nameserver[nameservers++] = strdup(arg[i]);
				DPRINTF("adding nameserver %s\n",arg[i]);
			}
		}
		if (0 != (arg = cfgfind(fp, "search"))) {
			for (i=1; arg[i] && searchdomains <= MAX_SEARCH; i++) {
				searchdomain[searchdomains++] = strdup(arg[i]);
				DPRINTF("adding search %s\n",arg[i]);
			}
		}
		fclose(fp);
	} else {
	    DPRINTF("failed to open %s\n", "resolv.conf");
	}
	DPRINTF("nameservers = %d\n", nameservers);
	return 0;
}
#endif

#ifdef L_closenameservers
void close_nameservers(void)
{

	while (nameservers > 0)
		free((void*)nameserver[--nameservers]);
}
#endif


#ifdef L_resolvename

const char *resolve_name(const char *name, int mailbox)
{
	struct in_addr in;
	int i;

	/* shortcut: is it a valid IP address to begin with? */
	if (inet_aton(name, &in))
		return name;

	open_nameservers();

	DPRINTF("looking up '%s', mailbox=%d, nameservers=%d\n",
			name, mailbox, nameservers);

	if (mailbox)
		i = resolve_mailbox(name, nameservers, nameserver, &in);
	else
		i = resolve_address(name, nameservers, nameserver, &in);

	if (i < 0)
		return 0;

	DPRINTF("success = '%s'\n", inet_ntoa(in));

	return inet_ntoa(in);
}
#endif

#ifdef L_gethostbyname

struct hostent *gethostbyname(const char *name)
{
	static struct hostent h;
	static char namebuf[256];
	static struct in_addr in;
	static struct in_addr *addr_list[2];
	unsigned char *packet;
	struct resolv_answer a;
	int i;
	int nest = 0;

	open_nameservers();

	if (!name)
		return 0;
	
	memset(&h, 0, sizeof(h));

	addr_list[0] = &in;
	addr_list[1] = 0;
	
	strcpy(namebuf, name);

	/* First check if this is already an address */
	if (inet_aton(name, &in)) {
	    h.h_name = namebuf;
	    h.h_addrtype = AF_INET;
	    h.h_length = sizeof(in);
	    h.h_addr_list = (char **) addr_list;
	    return &h;
	}

	for (;;) {

		i = dns_lookup(namebuf, 1, nameservers, nameserver, &packet, &a);

		if (i < 0)
			return 0;

		strncpy(namebuf, a.dotted, sizeof(namebuf));
		free(a.dotted);


		if (a.atype == T_CNAME) {		/* CNAME */
			DPRINTF("Got a CNAME in gethostbyname()\n");
			i = decode_dotted(packet, a.rdoffset, namebuf, sizeof(namebuf));
			free(packet);

			if (i < 0)
				return 0;
			if (++nest > MAX_RECURSE)
				return 0;
			continue;
		} else if (a.atype == T_A) {	/* ADDRESS */
			memcpy(&in, a.rdata, sizeof(in));
			h.h_name = namebuf;
			h.h_addrtype = AF_INET;
			h.h_length = sizeof(in);
			h.h_addr_list = (char **) addr_list;
			free(packet);
			break;
		} else {
			free(packet);
			return 0;
		}
	}

	return &h;
}
#endif

#ifdef L_gethostbyaddr

struct hostent *gethostbyaddr(const char *addr, int len, int type)
{
	static struct hostent h;
	static char namebuf[256];
	static struct in_addr in;
	static struct in_addr *addr_list[2];
	unsigned char *packet;
	struct resolv_answer a;
	int i;
	int nest = 0;

	if (!addr || (len != sizeof(in)) || (type != AF_INET))
		return 0;

	memcpy(&in.s_addr, addr, len);

	open_nameservers();

	memset(&h, 0, sizeof(h));

	addr_list[0] = &in;
	addr_list[1] = 0;

	sprintf(namebuf, "%d.%d.%d.%d.in-addr.arpa",
			(in.s_addr >> 24) & 0xff,
			(in.s_addr >> 16) & 0xff,
			(in.s_addr >> 8) & 0xff, 
			(in.s_addr >> 0) & 0xff);

	for (;;) {

		i = dns_lookup(namebuf, T_PTR, nameservers, nameserver, &packet, &a);

		if (i < 0)
			return 0;

		strncpy(namebuf, a.dotted, sizeof(namebuf));
		free(a.dotted);

		if (a.atype == T_CNAME) {		/* CNAME */
			DPRINTF("Got a CNAME in gethostbyaddr()\n");
			i = decode_dotted(packet, a.rdoffset, namebuf, sizeof(namebuf));
			free(packet);

			if (i < 0)
				return 0;
			if (++nest > MAX_RECURSE)
				return 0;
			continue;
		} else if (a.atype == T_PTR) {	/* ADDRESS */
			i = decode_dotted(packet, a.rdoffset, namebuf, sizeof(namebuf));
			free(packet);

			h.h_name = namebuf;
			h.h_addrtype = AF_INET;
			h.h_length = sizeof(in);
			h.h_addr_list = (char **) addr_list;
			break;
		} else {
			free(packet);
			return 0;
		}
	}

	return &h;
}
#endif