summaryrefslogtreecommitdiff
path: root/src/dns.cpp
blob: 385f8639ea91f97ec6b443f146f7f4432cdcdfca (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
/*       +------------------------------------+
 *       | Inspire Internet Relay Chat Daemon |
 *       +------------------------------------+
 *
 *  InspIRCd: (C) 2002-2007 InspIRCd Development Team
 * See: http://www.inspircd.org/wiki/index.php/Credits
 *
 * This program is free but copyrighted software; see
 *            the file COPYING for details.
 *
 * ---------------------------------------------------
 */

/*
dns.cpp - Nonblocking DNS functions.
Very very loosely based on the firedns library,
Copyright (C) 2002 Ian Gulliver. This file is no
longer anything like firedns, there are many major
differences between this code and the original.
Please do not assume that firedns works like this,
looks like this, walks like this or tastes like this.
*/

#include <sys/types.h>
#include <sys/socket.h>
#include <errno.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include "dns.h"
#include "inspircd.h"
#include "socketengine.h"
#include "configreader.h"
#include "socket.h"

using irc::sockets::insp_sockaddr;
using irc::sockets::insp_inaddr;
using irc::sockets::insp_ntoa;
using irc::sockets::insp_aton;

/** Masks to mask off the responses we get from the DNSRequest methods
 */
enum QueryInfo
{
	ERROR_MASK	= 0x10000	/* Result is an error */
};

/** Flags which can be ORed into a request or reply for different meanings
 */
enum QueryFlags
{
	FLAGS_MASK_RD		= 0x01,	/* Recursive */
	FLAGS_MASK_TC		= 0x02,
	FLAGS_MASK_AA		= 0x04,	/* Authoritative */
	FLAGS_MASK_OPCODE	= 0x78,
	FLAGS_MASK_QR		= 0x80,
	FLAGS_MASK_RCODE	= 0x0F,	/* Request */
	FLAGS_MASK_Z		= 0x70,
	FLAGS_MASK_RA 		= 0x80
};


/** Represents a dns resource record (rr)
 */
class ResourceRecord
{
 public:
	QueryType	type;		/* Record type */
	unsigned int	rr_class;	/* Record class */
	unsigned long	ttl;		/* Time to live */
	unsigned int	rdlength;	/* Record length */
};

/** Represents a dns request/reply header, and its payload as opaque data.
 */
class DNSHeader
{
 public:
	unsigned char	id[2];		/* Request id */
	unsigned int	flags1;		/* Flags */
	unsigned int	flags2;		/* Flags */
	unsigned int	qdcount;
	unsigned int	ancount;	/* Answer count */
	unsigned int	nscount;	/* Nameserver count */
	unsigned int	arcount;
	unsigned char	payload[512];	/* Packet payload */
};

class DNSRequest
{
 public:
	unsigned char   id[2];		/* Request id */
	unsigned char*  res;		/* Result processing buffer */
	unsigned int    rr_class;       /* Request class */
	QueryType       type;		/* Request type */
	insp_inaddr     myserver;       /* DNS server address*/
	DNS*            dnsobj;		/* DNS caller (where we get our FD from) */
	unsigned long	ttl;		/* Time to live */
	std::string     orig;		/* Original requested name/ip */

	DNSRequest(InspIRCd* Instance, DNS* dns, insp_inaddr server, int id, const std::string &original);
	~DNSRequest();
	DNSInfo ResultIsReady(DNSHeader &h, int length);
	int SendRequests(const DNSHeader *header, const int length, QueryType qt);
};

class RequestTimeout : public InspTimer
{
	InspIRCd* ServerInstance;
	DNSRequest* watch;
	int watchid;
 public:
	RequestTimeout(unsigned long n, InspIRCd* SI, DNSRequest* watching, int id) : InspTimer(n, time(NULL)), ServerInstance(SI), watch(watching), watchid(id)
	{
		ServerInstance->Log(DEBUG, "New DNS timeout set on %08x", watching);
	}

	void Tick(time_t TIME)
	{
		if (ServerInstance->Res->requests[watchid] == watch)
		{
			/* Still exists, whack it */
			if (ServerInstance->Res->Classes[watchid])
			{
				ServerInstance->Res->Classes[watchid]->OnError(RESOLVER_TIMEOUT, "Request timed out");
				delete ServerInstance->Res->Classes[watchid];
				ServerInstance->Res->Classes[watchid] = NULL;
			}
			ServerInstance->Res->requests[watchid] = NULL;
			delete watch;
			ServerInstance->Log(DEBUG, "DNS timeout on %08x squished pointer", watch);
			return;
		}
		ServerInstance->Log(DEBUG, "DNS timeout on %08x: result already received!", watch);
	}
};

/* Allocate the processing buffer */
DNSRequest::DNSRequest(InspIRCd* Instance, DNS* dns, insp_inaddr server, int id, const std::string &original) : dnsobj(dns)
{
	res = new unsigned char[512];
	*res = 0;
	memcpy(&myserver, &server, sizeof(insp_inaddr));
	orig = original;
	RequestTimeout* RT = new RequestTimeout(Instance->Config->dns_timeout ? Instance->Config->dns_timeout : 5, Instance, this, id);
	Instance->Timers->AddTimer(RT); /* The timer manager frees this */
}

/* Deallocate the processing buffer */
DNSRequest::~DNSRequest()
{
	delete[] res;
}

/** Fill a ResourceRecord class based on raw data input */
inline void DNS::FillResourceRecord(ResourceRecord* rr, const unsigned char *input)
{
	rr->type = (QueryType)((input[0] << 8) + input[1]);
	rr->rr_class = (input[2] << 8) + input[3];
	rr->ttl = (input[4] << 24) + (input[5] << 16) + (input[6] << 8) + input[7];
	rr->rdlength = (input[8] << 8) + input[9];
}

/** Fill a DNSHeader class based on raw data input of a given length */
inline void DNS::FillHeader(DNSHeader *header, const unsigned char *input, const int length)
{
	header->id[0] = input[0];
	header->id[1] = input[1];
	header->flags1 = input[2];
	header->flags2 = input[3];
	header->qdcount = (input[4] << 8) + input[5];
	header->ancount = (input[6] << 8) + input[7];
	header->nscount = (input[8] << 8) + input[9];
	header->arcount = (input[10] << 8) + input[11];
	memcpy(header->payload,&input[12],length);
}

/** Empty a DNSHeader class out into raw data, ready for transmission */
inline void DNS::EmptyHeader(unsigned char *output, const DNSHeader *header, const int length)
{
	output[0] = header->id[0];
	output[1] = header->id[1];
	output[2] = header->flags1;
	output[3] = header->flags2;
	output[4] = header->qdcount >> 8;
	output[5] = header->qdcount & 0xFF;
	output[6] = header->ancount >> 8;
	output[7] = header->ancount & 0xFF;
	output[8] = header->nscount >> 8;
	output[9] = header->nscount & 0xFF;
	output[10] = header->arcount >> 8;
	output[11] = header->arcount & 0xFF;
	memcpy(&output[12],header->payload,length);
}

/** Send requests we have previously built down the UDP socket */
int DNSRequest::SendRequests(const DNSHeader *header, const int length, QueryType qt)
{
	insp_sockaddr addr;
	unsigned char payload[sizeof(DNSHeader)];

	this->rr_class = 1;
	this->type = qt;
		
	DNS::EmptyHeader(payload,header,length);

	memset(&addr,0,sizeof(addr));
#ifdef IPV6
	memcpy(&addr.sin6_addr,&myserver,sizeof(addr.sin6_addr));
	addr.sin6_family = AF_FAMILY;
	addr.sin6_port = htons(DNS::QUERY_PORT);
#else
	memcpy(&addr.sin_addr.s_addr,&myserver,sizeof(addr.sin_addr));
	addr.sin_family = AF_FAMILY;
	addr.sin_port = htons(DNS::QUERY_PORT);
#endif
	if (sendto(dnsobj->GetFd(), payload, length + 12, 0, (sockaddr *) &addr, sizeof(addr)) == -1)
		return -1;

	return 0;
}

/** Add a query with a predefined header, and allocate an ID for it. */
DNSRequest* DNS::AddQuery(DNSHeader *header, int &id, const char* original)
{
	/* Is the DNS connection down? */
	if (this->GetFd() == -1)
		return NULL;
	
	/* Create an id */
	id = this->PRNG() & DNS::MAX_REQUEST_ID;

	/* If this id is already 'in flight', pick another. */
	while (requests[id])
		id = this->PRNG() & DNS::MAX_REQUEST_ID;

	DNSRequest* req = new DNSRequest(ServerInstance, this, this->myserver, id, original);

	header->id[0] = req->id[0] = id >> 8;
	header->id[1] = req->id[1] = id & 0xFF;
	header->flags1 = FLAGS_MASK_RD;
	header->flags2 = 0;
	header->qdcount = 1;
	header->ancount = 0;
	header->nscount = 0;
	header->arcount = 0;

	/* At this point we already know the id doesnt exist,
	 * so there needs to be no second check for the ::end()
	 */
	requests[id] = req;

	/* According to the C++ spec, new never returns NULL. */
	return req;
}

void DNS::Rehash()
{
	insp_inaddr addr;
	ip6munge = false;

	if (this->GetFd() > -1)
	{
		if (ServerInstance && ServerInstance->SE)
			ServerInstance->SE->DelFd(this);
		shutdown(this->GetFd(), 2);
		close(this->GetFd());
		this->SetFd(-1);

		/* Rehash the cache */
		dnscache* newcache = new dnscache();
		for (dnscache::iterator i = this->cache->begin(); i != this->cache->end(); i++)
			newcache->insert(*i);

		delete this->cache;
		this->cache = newcache;
	}
	else
	{
		/* Create initial dns cache */
		this->cache = new dnscache();
	}

	if (insp_aton(ServerInstance->Config->DNSServer,&addr) > 0)
	{
		memcpy(&myserver,&addr,sizeof(insp_inaddr));
		if ((strstr(ServerInstance->Config->DNSServer,"::ffff:") == (char*)&ServerInstance->Config->DNSServer) ||  (strstr(ServerInstance->Config->DNSServer,"::FFFF:") == (char*)&ServerInstance->Config->DNSServer))
		{
			ServerInstance->Log(DEFAULT,"WARNING: Using IPv4 addresses over IPv6 forces some DNS checks to be disabled.");
			ServerInstance->Log(DEFAULT,"         This should not cause a problem, however it is recommended you migrate");
			ServerInstance->Log(DEFAULT,"         to a true IPv6 environment.");
			this->ip6munge = true;
		}
		ServerInstance->Log(DEBUG,"Added nameserver '%s'",ServerInstance->Config->DNSServer);
	}
	else
	{
		ServerInstance->Log(DEBUG,"GACK! insp_aton says the nameserver '%s' is invalid!",ServerInstance->Config->DNSServer);
	}

	/* Initialize mastersocket */
	this->SetFd(socket(PF_PROTOCOL, SOCK_DGRAM, 0));
	if (this->GetFd() != -1)
	{
		/* Did it succeed? */
		if (fcntl(this->GetFd(), F_SETFL, O_NONBLOCK) != 0)
		{
			/* Couldn't make the socket nonblocking */
			shutdown(this->GetFd(),2);
			close(this->GetFd());
			this->SetFd(-1);
		}
	}
	else
	{
		ServerInstance->Log(DEBUG,"I cant socket() this socket! (%s)",strerror(errno));
	}

	/* Have we got a socket and is it nonblocking? */
	if (this->GetFd() != -1)
	{
#ifdef IPV6
		insp_sockaddr addr;
		memset(&addr,0,sizeof(addr));
		addr.sin6_family = AF_FAMILY;
		addr.sin6_port = 0;
		addr.sin6_addr = in6addr_any;
#else
		insp_sockaddr addr;
		memset(&addr,0,sizeof(addr));
		addr.sin_family = AF_FAMILY;
		addr.sin_port = 0;
		addr.sin_addr.s_addr = INADDR_ANY;
#endif
		/* Bind the port */
		if (bind(this->GetFd(),(sockaddr *)&addr,sizeof(addr)) != 0)
		{
			/* Failed to bind */
			ServerInstance->Log(DEBUG,"Cant bind DNS fd");
			shutdown(this->GetFd(),2);
			close(this->GetFd());
			this->SetFd(-1);
		}

		if (this->GetFd() >= 0)
		{
			ServerInstance->Log(DEBUG,"Add master socket %d",this->GetFd());
			/* Hook the descriptor into the socket engine */
			if (ServerInstance && ServerInstance->SE)
			{
				if (!ServerInstance->SE->AddFd(this))
				{
					ServerInstance->Log(DEFAULT,"Internal error starting DNS - hostnames will NOT resolve.");
					shutdown(this->GetFd(),2);
					close(this->GetFd());
					this->SetFd(-1);
				}
			}
		}
	}
}

/** Initialise the DNS UDP socket so that we can send requests */
DNS::DNS(InspIRCd* Instance) : ServerInstance(Instance)
{
	ServerInstance->Log(DEBUG,"DNS::DNS: Instance = %08x",Instance);

	/* Clear the Resolver class table */
	memset(Classes,0,sizeof(Classes));

	/* Clear the requests class table */
	memset(requests,0,sizeof(requests));

	/* Set the id of the next request to 0
	 */
	currid = 0;

	/* DNS::Rehash() sets this to a valid ptr
	 */
	this->cache = NULL;
	
	/* Again, DNS::Rehash() sets this to a
	 * valid value
	 */
	this->SetFd(-1);

	/* Actually read the settings
	 */
	this->Rehash();
}

/** Build a payload to be placed after the header, based upon input data, a resource type, a class and a pointer to a buffer */
int DNS::MakePayload(const char * const name, const QueryType rr, const unsigned short rr_class, unsigned char * const payload)
{
	short payloadpos = 0;
	const char* tempchr, *tempchr2 = name;
	unsigned short length;

	/* split name up into labels, create query */
	while ((tempchr = strchr(tempchr2,'.')) != NULL)
	{
		length = tempchr - tempchr2;
		if (payloadpos + length + 1 > 507)
			return -1;
		payload[payloadpos++] = length;
		memcpy(&payload[payloadpos],tempchr2,length);
		payloadpos += length;
		tempchr2 = &tempchr[1];
	}
	length = strlen(tempchr2);
	if (length)
	{
		if (payloadpos + length + 2 > 507)
			return -1;
		payload[payloadpos++] = length;
		memcpy(&payload[payloadpos],tempchr2,length);
		payloadpos += length;
		payload[payloadpos++] = 0;
	}
	if (payloadpos > 508)
		return -1;
	length = htons(rr);
	memcpy(&payload[payloadpos],&length,2);
	length = htons(rr_class);
	memcpy(&payload[payloadpos + 2],&length,2);
	return payloadpos + 4;
}

/** Start lookup of an hostname to an IP address */
int DNS::GetIP(const char *name)
{
	DNSHeader h;
	int id;
	int length;
	
	if ((length = this->MakePayload(name, DNS_QUERY_A, 1, (unsigned char*)&h.payload)) == -1)
		return -1;

	DNSRequest* req = this->AddQuery(&h, id, name);

	if ((!req) || (req->SendRequests(&h, length, DNS_QUERY_A) == -1))
		return -1;

	return id;
}

/** Start lookup of an hostname to an IPv6 address */
int DNS::GetIP6(const char *name)
{
	DNSHeader h;
	int id;
	int length;

	if ((length = this->MakePayload(name, DNS_QUERY_AAAA, 1, (unsigned char*)&h.payload)) == -1)
		return -1;

	DNSRequest* req = this->AddQuery(&h, id, name);

	if ((!req) || (req->SendRequests(&h, length, DNS_QUERY_AAAA) == -1))
		return -1;

	return id;
}

/** Start lookup of a cname to another name */
int DNS::GetCName(const char *alias)
{
	DNSHeader h;
	int id;
	int length;

	if ((length = this->MakePayload(alias, DNS_QUERY_CNAME, 1, (unsigned char*)&h.payload)) == -1)
		return -1;

	DNSRequest* req = this->AddQuery(&h, id, alias);

	if ((!req) || (req->SendRequests(&h, length, DNS_QUERY_CNAME) == -1))
		return -1;

	return id;
}

/** Start lookup of an IP address to a hostname */
int DNS::GetName(const insp_inaddr *ip)
{
	char query[128];
	DNSHeader h;
	int id;
	int length;

#ifdef IPV6
	unsigned char* c = (unsigned char*)&ip->s6_addr;
	if (c[0] == 0 && c[1] == 0 && c[2] == 0 && c[3] == 0 &&
	    c[4] == 0 && c[5] == 0 && c[6] == 0 && c[7] == 0 &&
	    c[8] == 0 && c[9] == 0 && c[10] == 0xFF && c[11] == 0xFF)
		sprintf(query,"%d.%d.%d.%d.in-addr.arpa",c[15],c[14],c[13],c[12]);
	else
		DNS::MakeIP6Int(query, (in6_addr*)ip);
#else
	unsigned char* c = (unsigned char*)&ip->s_addr;
	sprintf(query,"%d.%d.%d.%d.in-addr.arpa",c[3],c[2],c[1],c[0]);
#endif

	if ((length = this->MakePayload(query, DNS_QUERY_PTR, 1, (unsigned char*)&h.payload)) == -1)
		return -1;

	DNSRequest* req = this->AddQuery(&h, id, insp_ntoa(*ip));

	if ((!req) || (req->SendRequests(&h, length, DNS_QUERY_PTR) == -1))
		return -1;

	return id;
}

/** Start lookup of an IP address to a hostname */
int DNS::GetNameForce(const char *ip, ForceProtocol fp)
{
	char query[128];
	DNSHeader h;
	int id;
	int length;
#ifdef SUPPORT_IP6LINKS
	if (fp == PROTOCOL_IPV6)
	{
		in6_addr i;
		if (inet_pton(AF_INET6, ip, &i) > 0)
		{
			DNS::MakeIP6Int(query, &i);
		}
		else
			/* Invalid IP address */
			return -1;
	}
	else
#endif
	{
		in_addr i;
		if (inet_aton(ip, &i))
		{
			unsigned char* c = (unsigned char*)&i.s_addr;
			sprintf(query,"%d.%d.%d.%d.in-addr.arpa",c[3],c[2],c[1],c[0]);
		}
		else
			/* Invalid IP address */
			return -1;
	}

	ServerInstance->Log(DEBUG,"DNS::GetNameForce: %s %d",query, fp);

	if ((length = this->MakePayload(query, DNS_QUERY_PTR, 1, (unsigned char*)&h.payload)) == -1)
		return -1;

	DNSRequest* req = this->AddQuery(&h, id, ip);

	if ((!req) || (req->SendRequests(&h, length, DNS_QUERY_PTR) == -1))
		return -1;

	return id;
}

/** Build an ipv6 reverse domain from an in6_addr
 */
void DNS::MakeIP6Int(char* query, const in6_addr *ip)
{
#ifdef SUPPORT_IP6LINKS
	const char* hex = "0123456789abcdef";
	for (int index = 31; index >= 0; index--) /* for() loop steps twice per byte */
	{
		if (index % 2)
			/* low nibble */
			*query++ = hex[ip->s6_addr[index / 2] & 0x0F];
		else
			/* high nibble */
			*query++ = hex[(ip->s6_addr[index / 2] & 0xF0) >> 4];
		*query++ = '.'; /* Seperator */
	}
	strcpy(query,"ip6.arpa"); /* Suffix the string */
#else
	*query = 0;
#endif
}

/** Return the next id which is ready, and the result attached to it */
DNSResult DNS::GetResult()
{
	/* Fetch dns query response and decide where it belongs */
	DNSHeader header;
	DNSRequest *req;
	unsigned char buffer[sizeof(DNSHeader)];
	sockaddr from;
	socklen_t x = sizeof(from);
	const char* ipaddr_from = "";
	unsigned short int port_from = 0;

	int length = recvfrom(this->GetFd(),buffer,sizeof(DNSHeader),0,&from,&x);

	if (length < 0)
		ServerInstance->Log(DEBUG,"Error in recvfrom()! (%s)",strerror(errno));

	/* Did we get the whole header? */
	if (length < 12)
	{
		/* Nope - something screwed up. */
		ServerInstance->Log(DEBUG,"Whole header not read!");
		return DNSResult(-1,"",0,"");
	}

	/* Check wether the reply came from a different DNS
	 * server to the one we sent it to, or the source-port
	 * is not 53.
	 * A user could in theory still spoof dns packets anyway
	 * but this is less trivial than just sending garbage
	 * to the client, which is possible without this check.
	 *
	 * -- Thanks jilles for pointing this one out.
	 */
#ifdef IPV6
	ipaddr_from = insp_ntoa(((sockaddr_in6*)&from)->sin6_addr);
	port_from = ntohs(((sockaddr_in6*)&from)->sin6_port);
#else
	ipaddr_from = insp_ntoa(((sockaddr_in*)&from)->sin_addr);
	port_from = ntohs(((sockaddr_in*)&from)->sin_port);
#endif

	/* We cant perform this security check if you're using 4in6.
	 * Tough luck to you, choose one or't other!
	 */
	if (!ip6munge)
	{
		if ((port_from != DNS::QUERY_PORT) || (strcasecmp(ipaddr_from, ServerInstance->Config->DNSServer)))
		{
			ServerInstance->Log(DEBUG,"port %d is not 53, or %s is not %s",port_from, ipaddr_from, ServerInstance->Config->DNSServer);
			return DNSResult(-1,"",0,"");
		}
	}

	/* Put the read header info into a header class */
	DNS::FillHeader(&header,buffer,length - 12);

	/* Get the id of this request.
	 * Its a 16 bit value stored in two char's,
	 * so we use logic shifts to create the value.
	 */
	unsigned long this_id = header.id[1] + (header.id[0] << 8);

	/* Do we have a pending request matching this id? */
	if (!requests[this_id])
	{
		/* Somehow we got a DNS response for a request we never made... */
		ServerInstance->Log(DEBUG,"DNS: got a response for a query we didnt send with fd=%d queryid=%d",this->GetFd(),this_id);
		return DNSResult(-1,"",0,"");
	}
	else
	{
		/* Remove the query from the list of pending queries */
		req = requests[this_id];
		requests[this_id] = NULL;
	}

	/* Inform the DNSRequest class that it has a result to be read.
	 * When its finished it will return a DNSInfo which is a pair of
	 * unsigned char* resource record data, and an error message.
	 */
	DNSInfo data = req->ResultIsReady(header, length);
	std::string resultstr;

	/* Check if we got a result, if we didnt, its an error */
	if (data.first == NULL)
	{
		/* An error.
		 * Mask the ID with the value of ERROR_MASK, so that
		 * the dns_deal_with_classes() function knows that its
		 * an error response and needs to be treated uniquely.
		 * Put the error message in the second field.
		 */
		std::string ro = req->orig;
		delete req;
		return DNSResult(this_id | ERROR_MASK, data.second, 0, ro);
	}
	else
	{
		unsigned long ttl = req->ttl;
		char formatted[128];

		/* Forward lookups come back as binary data. We must format them into ascii */
		switch (req->type)
		{
			case DNS_QUERY_A:
				snprintf(formatted,16,"%u.%u.%u.%u",data.first[0],data.first[1],data.first[2],data.first[3]);
				resultstr = formatted;
			break;

			case DNS_QUERY_AAAA:
			{
				snprintf(formatted,40,"%x:%x:%x:%x:%x:%x:%x:%x",
						(ntohs(data.first[0]) + ntohs(data.first[1] << 8)),
						(ntohs(data.first[2]) + ntohs(data.first[3] << 8)),
						(ntohs(data.first[4]) + ntohs(data.first[5] << 8)),
						(ntohs(data.first[6]) + ntohs(data.first[7] << 8)),
						(ntohs(data.first[8]) + ntohs(data.first[9] << 8)),
						(ntohs(data.first[10]) + ntohs(data.first[11] << 8)),
						(ntohs(data.first[12]) + ntohs(data.first[13] << 8)),
						(ntohs(data.first[14]) + ntohs(data.first[15] << 8)));
				char* c = strstr(formatted,":0:");
				if (c != NULL)
				{
					memmove(c+1,c+2,strlen(c+2) + 1);
					c += 2;
					while (memcmp(c,"0:",2) == 0)
						memmove(c,c+2,strlen(c+2) + 1);
					if (memcmp(c,"0",2) == 0)
						*c = 0;
					if (memcmp(formatted,"0::",3) == 0)
						memmove(formatted,formatted + 1, strlen(formatted + 1) + 1);
				}
				resultstr = formatted;

				/* Special case. Sending ::1 around between servers
				 * and to clients is dangerous, because the : on the
				 * start makes the client or server interpret the IP
				 * as the last parameter on the line with a value ":1".
				 */
				if (*formatted == ':')
					resultstr = "0" + resultstr;
			}
			break;

			case DNS_QUERY_CNAME:
				/* Identical handling to PTR */

			case DNS_QUERY_PTR:
				/* Reverse lookups just come back as char* */
				resultstr = std::string((const char*)data.first);
			break;

			default:
				ServerInstance->Log(DEBUG,"WARNING: Somehow we made a request for a DNS_QUERY_PTR4 or DNS_QUERY_PTR6, but these arent real rr types!");
			break;
			
		}

		/* Build the reply with the id and hostname/ip in it */
		std::string ro = req->orig;
		delete req;
		return DNSResult(this_id,resultstr,ttl,ro);
	}
}

/** A result is ready, process it */
DNSInfo DNSRequest::ResultIsReady(DNSHeader &header, int length)
{
	int i = 0;
	int q = 0;
	int curanswer, o;
	ResourceRecord rr;
 	unsigned short ptr;

	/* This is just to keep _FORTIFY_SOURCE happy */
	rr.type = DNS_QUERY_NONE;
	rr.rdlength = 0;

	if (!(header.flags1 & FLAGS_MASK_QR))
		return std::make_pair((unsigned char*)NULL,"Not a query result");

	if (header.flags1 & FLAGS_MASK_OPCODE)
		return std::make_pair((unsigned char*)NULL,"Unexpected value in DNS reply packet");

	if (header.flags2 & FLAGS_MASK_RCODE)
		return std::make_pair((unsigned char*)NULL,"Domain name not found");

	if (header.ancount < 1)
		return std::make_pair((unsigned char*)NULL,"No resource records returned");

	/* Subtract the length of the header from the length of the packet */
	length -= 12;

	while ((unsigned int)q < header.qdcount && i < length)
	{
		if (header.payload[i] > 63)
		{
			i += 6;
			q++;
		}
		else
		{
			if (header.payload[i] == 0)
			{
				q++;
				i += 5;
			}
			else i += header.payload[i] + 1;
		}
	}
	curanswer = 0;
	while ((unsigned)curanswer < header.ancount)
	{
		q = 0;
		while (q == 0 && i < length)
		{
			if (header.payload[i] > 63)
			{
				i += 2;
				q = 1;
			}
			else
			{
				if (header.payload[i] == 0)
				{
					i++;
					q = 1;
				}
				else i += header.payload[i] + 1; /* skip length and label */
			}
		}
		if (length - i < 10)
			return std::make_pair((unsigned char*)NULL,"Incorrectly sized DNS reply");

		DNS::FillResourceRecord(&rr,&header.payload[i]);
		i += 10;
		if (rr.type != this->type)
		{
			curanswer++;
			i += rr.rdlength;
			continue;
		}
		if (rr.rr_class != this->rr_class)
		{
			curanswer++;
			i += rr.rdlength;
			continue;
		}
		break;
	}
	if ((unsigned int)curanswer == header.ancount)
		return std::make_pair((unsigned char*)NULL,"No valid answers");

	if (i + rr.rdlength > (unsigned int)length)
		return std::make_pair((unsigned char*)NULL,"Resource record larger than stated");

	if (rr.rdlength > 1023)
		return std::make_pair((unsigned char*)NULL,"Resource record too large");

	this->ttl = rr.ttl;

	switch (rr.type)
	{
		case DNS_QUERY_CNAME:
			/* CNAME and PTR have the same processing code */
		case DNS_QUERY_PTR:
			o = 0;
			q = 0;
			while (q == 0 && i < length && o + 256 < 1023)
			{
				if (header.payload[i] > 63)
				{
					memcpy(&ptr,&header.payload[i],2);
					i = ntohs(ptr) - 0xC000 - 12;
				}
				else
				{
					if (header.payload[i] == 0)
					{
						q = 1;
					}
					else
					{
						res[o] = 0;
						if (o != 0)
							res[o++] = '.';
						memcpy(&res[o],&header.payload[i + 1],header.payload[i]);
						o += header.payload[i];
						i += header.payload[i] + 1;
					}
				}
			}
			res[o] = 0;
		break;
		case DNS_QUERY_AAAA:
			memcpy(res,&header.payload[i],rr.rdlength);
			res[rr.rdlength] = 0;
		break;
		case DNS_QUERY_A:
			memcpy(res,&header.payload[i],rr.rdlength);
			res[rr.rdlength] = 0;
		break;
		default:
			memcpy(res,&header.payload[i],rr.rdlength);
			res[rr.rdlength] = 0;
		break;
	}
	return std::make_pair(res,"No error");;
}

/** Close the master socket */
DNS::~DNS()
{
	shutdown(this->GetFd(), 2);
	close(this->GetFd());
}

CachedQuery* DNS::GetCache(const std::string &source)
{
	dnscache::iterator x = cache->find(source.c_str());
	if (x != cache->end())
		return &(x->second);
	else
		return NULL;
}
	        
void DNS::DelCache(const std::string &source)
{
	cache->erase(source.c_str());
}

void Resolver::OnLookupComplete(const std::string &result, unsigned int ttl)
{
	throw CoreException("Someone didnt define an OnLookupComplete method for their Resolver class!");
}

/** High level abstraction of dns used by application at large */
Resolver::Resolver(InspIRCd* Instance, const std::string &source, QueryType qt, bool &cached, Module* creator) : ServerInstance(Instance), Creator(creator), input(source), querytype(qt)
{
	ServerInstance->Log(DEBUG,"Instance: %08x %08x",Instance, ServerInstance);

	cached = false;

	CachedQuery* CQ = ServerInstance->Res->GetCache(source);
	if (CQ)
	{
		int time_left = CQ->CalcTTLRemaining();
		if (!time_left)
		{
			ServerInstance->Log(DEBUG,"Cached but EXPIRED result: %s", CQ->data.c_str());
			ServerInstance->Res->DelCache(source);
		}
		else
		{
			cached = true;
			ServerInstance->Log(DEBUG,"Cached result: %s", CQ->data.c_str());
			OnLookupComplete(CQ->data, time_left);
			return;
		}
	}

	insp_inaddr binip;

	switch (querytype)
	{
		case DNS_QUERY_A:
			this->myid = ServerInstance->Res->GetIP(source.c_str());
		break;

		case DNS_QUERY_PTR:
			if (insp_aton(source.c_str(), &binip) > 0)
			{
				/* Valid ip address */
				this->myid = ServerInstance->Res->GetName(&binip);
			}
			else
			{
				this->OnError(RESOLVER_BADIP, "Bad IP address for reverse lookup");
				throw ModuleException("Resolver: Bad IP address");
				return;
			}
		break;

		case DNS_QUERY_PTR4:
			querytype = DNS_QUERY_PTR;
			this->myid = ServerInstance->Res->GetNameForce(source.c_str(), PROTOCOL_IPV4);
		break;

		case DNS_QUERY_PTR6:
			querytype = DNS_QUERY_PTR;
			this->myid = ServerInstance->Res->GetNameForce(source.c_str(), PROTOCOL_IPV6);
		break;

		case DNS_QUERY_AAAA:
			this->myid = ServerInstance->Res->GetIP6(source.c_str());
		break;

		case DNS_QUERY_CNAME:
			this->myid = ServerInstance->Res->GetCName(source.c_str());
		break;

		default:
			this->myid = -1;
		break;
	}
	if (this->myid == -1)
	{
		ServerInstance->Log(DEBUG,"Resolver::Resolver: Could not get an id!");
		this->OnError(RESOLVER_NSDOWN, "Nameserver is down");
		throw ModuleException("Resolver: Couldnt get an id to make a request");
		/* We shouldnt get here really */
		return;
	}

	ServerInstance->Log(DEBUG,"Resolver::Resolver: this->myid=%d",this->myid);
}

/** Called when an error occurs */
void Resolver::OnError(ResolverError e, const std::string &errormessage)
{
	/* Nothing in here */
}

/** Destroy a resolver */
Resolver::~Resolver()
{
	/* Nothing here (yet) either */
}

/** Get the request id associated with this class */
int Resolver::GetId()
{
	return this->myid;
}

Module* Resolver::GetCreator()
{
	return this->Creator;
}

/** Process a socket read event */
void DNS::HandleEvent(EventType et, int errornum)
{
	/* Fetch the id and result of the next available packet */
	DNSResult res = this->GetResult();
	/* Is there a usable request id? */
	if (res.id != -1)
	{
		/* Its an error reply */
		if (res.id & ERROR_MASK)
		{
			/* Mask off the error bit */
			res.id -= ERROR_MASK;
			/* Marshall the error to the correct class */
			ServerInstance->Log(DEBUG,"Error available, id=%d",res.id);
			if (Classes[res.id])
			{
				if (ServerInstance && ServerInstance->stats)
					ServerInstance->stats->statsDnsBad++;
				Classes[res.id]->OnError(RESOLVER_NXDOMAIN, res.result);
				delete Classes[res.id];
				Classes[res.id] = NULL;
			}
		}
		else
		{
			/* It is a non-error result */
			ServerInstance->Log(DEBUG,"Result available, id=%d",res.id);
			/* Marshall the result to the correct class */
			if (Classes[res.id])
			{
				if (ServerInstance && ServerInstance->stats)
					ServerInstance->stats->statsDnsGood++;

				if (!this->GetCache(res.original.c_str()))
				{
					ServerInstance->Log(DEBUG,"Caching result: %s->%s for %lu secs", res.original.c_str(), res.result.c_str(), res.ttl);
					this->cache->insert(std::make_pair(res.original.c_str(), CachedQuery(res.result, res.ttl)));
				}

				Classes[res.id]->OnLookupComplete(res.result, res.ttl);
				delete Classes[res.id];
				Classes[res.id] = NULL;
			}
		}

		if (ServerInstance && ServerInstance->stats)
			ServerInstance->stats->statsDns++;
	}
}

/** Add a derived Resolver to the working set */
bool DNS::AddResolverClass(Resolver* r)
{
	/* Check the pointers validity and the id's validity */
	if ((r) && (r->GetId() > -1))
	{
		/* Check the slot isnt already occupied -
		 * This should NEVER happen unless we have
		 * a severely broken DNS server somewhere
		 */
		if (!Classes[r->GetId()])
		{
			/* Set up the pointer to the class */
			Classes[r->GetId()] = r;
			return true;
		}
		else
			/* Duplicate id */
			return false;
	}
	else
	{
		/* Pointer or id not valid.
		 * Free the item and return
		 */
		if (r)
			delete r;

		return false;
	}
}

void DNS::CleanResolvers(Module* module)
{
	for (int i = 0; i < MAX_REQUEST_ID; i++)
	{
		if (Classes[i])
		{
			if (Classes[i]->GetCreator() == module)
			{
				Classes[i]->OnError(RESLOVER_FORCEUNLOAD, "Parent module is unloading");
				delete Classes[i];
				Classes[i] = NULL;
			}
		}
	}
}

/** Generate pseudo-random number */
unsigned long DNS::PRNG()
{
	unsigned long val = 0;
	timeval n;
	serverstats* s = ServerInstance->stats;
	gettimeofday(&n,NULL);
	val = (n.tv_usec ^ getpid() ^ geteuid() ^ (this->currid++)) ^ s->statsAccept + n.tv_sec;
	val = val + s->statsCollisions ^ s->statsDnsGood - s->statsDnsBad;
	val += (s->statsConnects ^ (unsigned long)s->statsSent ^ (unsigned long)s->statsRecv) - s->BoundPortCount;
	return val;
}