1 /* -*- Mode: C; tab-width: 4 -*-
3 * Copyright (c) 2012-2013 Apple Inc. All rights reserved.
5 * Licensed under the Apache License, Version 2.0 (the "License");
6 * you may not use this file except in compliance with the License.
7 * You may obtain a copy of the License at
9 * http://www.apache.org/licenses/LICENSE-2.0
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
18 #include "mDNSEmbeddedAPI.h"
19 #include "CryptoAlg.h"
20 #include "anonymous.h"
21 #include "DNSCommon.h"
23 // Define ANONYMOUS_DISABLED to remove all the anonymous functionality
24 // and use the stub functions implemented later in this file.
26 #ifndef ANONYMOUS_DISABLED
28 #define ANON_NSEC3_ITERATIONS 1
30 struct AnonInfoResourceRecord_struct
32 ResourceRecord resrec;
36 typedef struct AnonInfoResourceRecord_struct AnonInfoResourceRecord;
38 mDNSlocal mDNSBool InitializeNSEC3Record(ResourceRecord *rr, const mDNSu8 *AnonData, int len, mDNSu32 salt)
41 rdataNSEC3 *nsec3 = (rdataNSEC3 *)rr->rdata->u.data;
43 unsigned short iter = ANON_NSEC3_ITERATIONS;
45 const mDNSu8 hashName[NSEC3_MAX_HASH_LEN];
47 // Construct the RDATA first and construct the owner name based on that.
48 ptr = (const mDNSu8 *)&salt;
49 debugf("InitializeNSEC3Record: %x%x%x%x, name %##s", ptr[0], ptr[1], ptr[2], ptr[3], rr->name->c);
52 nsec3->alg = SHA1_DIGEST_TYPE;
54 nsec3->iterations = swap16(iter);
55 nsec3->saltLength = 4;
56 tmp = (mDNSu8 *)&nsec3->salt;
62 // hashLength, nxt, bitmap
63 *tmp++ = SHA1_HASH_LENGTH; // hash length
65 tmp += SHA1_HASH_LENGTH;
66 *tmp++ = 0; // window number
67 *tmp++ = NSEC_MCAST_WINDOW_SIZE; // window length
68 mDNSPlatformMemZero(tmp, NSEC_MCAST_WINDOW_SIZE);
69 tmp[kDNSType_PTR >> 3] |= 128 >> (kDNSType_PTR & 7);
71 // Hash the base service name + salt + AnonData
72 if (!NSEC3HashName(rr->name, nsec3, AnonData, len, hashName, &hlen))
74 LogMsg("InitializeNSEC3Record: NSEC3HashName failed for %##s", rr->name->c);
77 if (hlen != SHA1_HASH_LENGTH)
79 LogMsg("InitializeNSEC3Record: hlen wrong %d", hlen);
82 mDNSPlatformMemCopy(nxt, hashName, hlen);
87 mDNSlocal ResourceRecord *ConstructNSEC3Record(const domainname *service, const mDNSu8 *AnonData, int len, mDNSu32 salt)
93 // We are just allocating an RData which has StandardAuthRDSize
94 if (StandardAuthRDSize < MCAST_NSEC3_RDLENGTH)
96 LogMsg("ConstructNSEC3Record: StandardAuthRDSize %d smaller than MCAST_NSEC3_RDLENGTH %d", StandardAuthRDSize, MCAST_NSEC3_RDLENGTH);
100 dlen = DomainNameLength(service);
102 // Allocate space for the name and RData.
103 rr = mDNSPlatformMemAllocate(sizeof(ResourceRecord) + dlen + sizeof(RData));
106 name = (domainname *)((mDNSu8 *)rr + sizeof(ResourceRecord));
107 rr->RecordType = kDNSRecordTypePacketAuth;
108 rr->InterfaceID = mDNSInterface_Any;
109 rr->name = (const domainname *)name;
110 rr->rrtype = kDNSType_NSEC3;
111 rr->rrclass = kDNSClass_IN;
112 rr->rroriginalttl = kStandardTTL;
113 rr->rDNSServer = mDNSNULL;
114 rr->rdlength = MCAST_NSEC3_RDLENGTH;
115 rr->rdestimate = MCAST_NSEC3_RDLENGTH;
116 rr->rdata = (RData *)((mDNSu8 *)rr->name + dlen);
118 AssignDomainName(name, service);
119 if (!InitializeNSEC3Record(rr, AnonData, len, salt))
121 mDNSPlatformMemFree(rr);
127 mDNSlocal ResourceRecord *CopyNSEC3ResourceRecord(AnonymousInfo *si, const ResourceRecord *rr)
129 AnonInfoResourceRecord *anonRR;
134 if (rr->rdlength < MCAST_NSEC3_RDLENGTH)
136 LogMsg("CopyNSEC3ResourceRecord: rdlength %d smaller than MCAST_NSEC3_RDLENGTH %d", rr->rdlength, MCAST_NSEC3_RDLENGTH);
139 // Allocate space for the name and the rdata along with the ResourceRecord
140 neededLen = rr->rdlength + DomainNameLength(rr->name);
141 extraLen = (neededLen > sizeof(RDataBody)) ? (neededLen - sizeof(RDataBody)) : 0;
142 anonRR = (AnonInfoResourceRecord *)mDNSPlatformMemAllocate(sizeof(AnonInfoResourceRecord) + extraLen);
146 anonRR->resrec = *rr;
148 anonRR->rdatastorage.MaxRDLength = rr->rdlength;
149 mDNSPlatformMemCopy(anonRR->rdatastorage.u.data, rr->rdata->u.data, rr->rdlength);
151 name = (domainname *)(anonRR->rdatastorage.u.data + rr->rdlength);
152 AssignDomainName(name, rr->name);
154 anonRR->resrec.name = name;
155 anonRR->resrec.rdata = &anonRR->rdatastorage;
157 si->nsec3RR = (ResourceRecord *)anonRR;
162 // When a service is started or a browse is started with the Anonymous data, we allocate a new random
163 // number and based on that allocate a new NSEC3 resource record whose hash is a function of random number (salt) and
164 // the anonymous data.
166 // If we receive a packet with the NSEC3 option, we need to cache that along with the resource record so that we can
167 // check against the question to see whether it answers them or not. In that case, we pass the "rr" that we received.
168 mDNSexport AnonymousInfo *AllocateAnonInfo(const domainname *service, const mDNSu8 *data, int len, const ResourceRecord *rr)
171 ai = (AnonymousInfo *)mDNSPlatformMemAllocate(sizeof(AnonymousInfo));
176 mDNSPlatformMemZero(ai, sizeof(AnonymousInfo));
179 if (!CopyNSEC3ResourceRecord(ai, rr))
181 mDNSPlatformMemFree(ai);
186 ai->salt = mDNSRandom(0xFFFFFFFF);
187 ai->AnonData = mDNSPlatformMemAllocate(len);
190 mDNSPlatformMemFree(ai);
193 ai->AnonDataLen = len;
194 mDNSPlatformMemCopy(ai->AnonData, data, len);
195 ai->nsec3RR = ConstructNSEC3Record(service, data, len, ai->salt);
198 mDNSPlatformMemFree(ai);
204 mDNSexport void FreeAnonInfo(AnonymousInfo *ai)
207 mDNSPlatformMemFree(ai->nsec3RR);
209 mDNSPlatformMemFree(ai->AnonData);
210 mDNSPlatformMemFree(ai);
213 mDNSexport void ReInitAnonInfo(AnonymousInfo **AnonInfo, const domainname *name)
217 AnonymousInfo *ai = *AnonInfo;
218 *AnonInfo = AllocateAnonInfo(name, ai->AnonData, ai->AnonDataLen, mDNSNULL);
226 // This function should be used only if you know that the question and
227 // the resource record belongs to the same set. The main usage is
228 // in ProcessQuery where we find the question to be part of the same
229 // set as the resource record, but it needs the AnonData to be
230 // initialized so that it can walk the cache records to see if they
231 // answer the question.
232 mDNSexport void SetAnonData(DNSQuestion *q, ResourceRecord *rr, mDNSBool ForQuestion)
234 if (!q->AnonInfo || !rr->AnonInfo)
236 LogMsg("SetAnonData: question %##s(%p), rr %##s(%p), NULL", q->qname.c, q->AnonInfo, rr->name->c, rr->AnonInfo);
240 debugf("SetAnonData: question %##s(%p), rr %##s(%p)", q->qname.c, q->AnonInfo, rr->name->c, rr->AnonInfo);
243 if (q->AnonInfo->AnonDataLen < rr->AnonInfo->AnonDataLen)
245 mDNSPlatformMemFree(q->AnonInfo->AnonData);
246 q->AnonInfo->AnonData = mDNSNULL;
249 if (!q->AnonInfo->AnonData)
251 q->AnonInfo->AnonData = mDNSPlatformMemAllocate(rr->AnonInfo->AnonDataLen);
252 if (!q->AnonInfo->AnonData)
255 mDNSPlatformMemCopy(q->AnonInfo->AnonData, rr->AnonInfo->AnonData, rr->AnonInfo->AnonDataLen);
256 q->AnonInfo->AnonDataLen = rr->AnonInfo->AnonDataLen;
260 if (rr->AnonInfo->AnonDataLen < q->AnonInfo->AnonDataLen)
262 mDNSPlatformMemFree(rr->AnonInfo->AnonData);
263 rr->AnonInfo->AnonData = mDNSNULL;
266 if (!rr->AnonInfo->AnonData)
268 rr->AnonInfo->AnonData = mDNSPlatformMemAllocate(q->AnonInfo->AnonDataLen);
269 if (!rr->AnonInfo->AnonData)
272 mDNSPlatformMemCopy(rr->AnonInfo->AnonData, q->AnonInfo->AnonData, q->AnonInfo->AnonDataLen);
273 rr->AnonInfo->AnonDataLen = q->AnonInfo->AnonDataLen;
277 // returns -1 if the caller should ignore the result
278 // returns 1 if the record answers the question
279 // returns 0 if the record does not answer the question
280 mDNSexport int AnonInfoAnswersQuestion(const ResourceRecord *const rr, const DNSQuestion *const q)
282 mDNSexport mDNS mDNSStorage;
283 ResourceRecord *nsec3RR;
285 AnonymousInfo *qai, *rai;
292 mDNSu8 hashName[NSEC3_MAX_HASH_LEN];
293 mDNSPlatformMemZero(hashName, sizeof(hashName));
295 debugf("AnonInfoAnswersQuestion: question qname %##s", q->qname.c);
297 // Currently only PTR records can have anonymous information
298 if (q->qtype != kDNSType_PTR)
303 // We allow anonymous questions to be answered by both normal services (without the
304 // anonymous information) and anonymous services that are part of the same set. And
305 // normal questions discover normal services and all anonymous services.
307 // The three cases have been enumerated clearly even though they all behave the
311 debugf("AnonInfoAnswersQuestion: not a anonymous type question");
320 debugf("AnonInfoAnswersQuestion: Question %##s not answered using anonymous record %##s", q->qname.c, rr->name->c);
329 debugf("AnonInfoAnswersQuestion: not a anonymous type record");
334 // case 4: We have the anonymous information both in the question and the record. We need
335 // two sets of information to validate.
337 // 1) Anonymous data that identifies the set/group
338 // 2) NSEC3 record that contains the hash and the salt
340 // If the question is a remote one, it does not have the anonymous information to validate (just
341 // the NSEC3 record) and hence the anonymous data should come from the local resource record. If the
342 // question is local, it can come from either of them and if there is a mismatch between the
343 // question and record, it won't validate.
348 if (qai->AnonData && rai->AnonData)
350 // Before a cache record is created, if there is a matching question i.e., part
351 // of the same set, then when the cache is created we also set the anonymous
352 // information. Otherwise, the cache record contains just the NSEC3 record and we
353 // won't be here for that case.
355 // It is also possible that a local question is matched against the local AuthRecord
356 // as that is also the case for which the AnonData would be non-NULL for both.
357 // We match questions against AuthRecords (rather than the cache) for LocalOnly case and
358 // to see whether a .local query should be suppressed or not. The latter never happens
359 // because PTR queries are never suppressed.
361 // If they don't belong to the same anonymous set, then no point in validating.
362 if ((qai->AnonDataLen != rai->AnonDataLen) ||
363 mDNSPlatformMemCmp(qai->AnonData, rai->AnonData, qai->AnonDataLen) != 0)
365 debugf("AnonInfoAnswersQuestion: AnonData mis-match for record %s question %##s ",
366 RRDisplayString(&mDNSStorage, rr), q->qname.c);
369 // AnonData matches i.e they belong to the same group and the same service.
370 LogInfo("AnonInfoAnswersQuestion: Answering qname %##s, rname %##s, without validation", q->qname.c,
376 debugf("AnonInfoAnswersQuestion: question %p, record %p", qai->AnonData, rai->AnonData);
381 // If there is AnonData, then this is a local question. The
382 // NSEC3 RR comes from the resource record which could be part
383 // of the cache or local auth record. The cache entry could
384 // be from a remote host or created when we heard our own
385 // announcements. In any case, we use that to see if it matches
387 AnonData = qai->AnonData;
388 AnonDataLen = qai->AnonDataLen;
389 nsec3RR = rai->nsec3RR;
393 // Remote question or hearing our own question back
394 AnonData = rai->AnonData;
395 AnonDataLen = rai->AnonDataLen;
396 nsec3RR = qai->nsec3RR;
399 if (!AnonData || !nsec3RR)
401 // AnonData can be NULL for the cache entry and if we are hearing our own question back, AnonData is NULL for
402 // that too and we can end up here for that case.
403 debugf("AnonInfoAnswersQuestion: AnonData %p or nsec3RR %p, NULL for question %##s, record %s", AnonData, nsec3RR,
404 q->qname.c, RRDisplayString(&mDNSStorage, rr));
407 debugf("AnonInfoAnswersQuestion: Validating question %##s, ResourceRecord %s", q->qname.c, RRDisplayString(&mDNSStorage, nsec3RR));
410 nsec3 = (rdataNSEC3 *)nsec3RR->rdata->u.data;
412 if (!NSEC3HashName(nsec3RR->name, nsec3, AnonData, AnonDataLen, hashName, &hlen))
414 LogMsg("AnonInfoAnswersQuestion: NSEC3HashName failed for %##s", nsec3RR->name->c);
417 if (hlen != SHA1_HASH_LENGTH)
419 LogMsg("AnonInfoAnswersQuestion: hlen wrong %d", hlen);
423 NSEC3Parse(nsec3RR, mDNSNULL, &nxtLength, &nxtName, mDNSNULL, mDNSNULL);
425 if (hlen != nxtLength)
427 LogMsg("AnonInfoAnswersQuestion: ERROR!! hlen %d not same as nxtLength %d", hlen, nxtLength);
431 for (i = 0; i < nxtLength; i++)
433 if (nxtName[i] != hashName[i])
435 debugf("AnonInfoAnswersQuestion: mismatch output %x, digest %x, i %d", nxtName[i+1], hashName[i], i);
439 LogInfo("AnonInfoAnswersQuestion: ResourceRecord %s matched question %##s (%s)", RRDisplayString(&mDNSStorage, nsec3RR), q->qname.c, DNSTypeName(q->qtype));
443 // Find a matching NSEC3 record for the name. We parse the questions and the records in the packet in order.
444 // Similarly we also parse the NSEC3 records in order and this mapping to the questions and records
446 mDNSlocal CacheRecord *FindMatchingNSEC3ForName(mDNS *const m, CacheRecord **nsec3, const domainname *name)
449 CacheRecord **prev = nsec3;
453 for (cr = *nsec3; cr; cr = cr->next)
455 if (SameDomainName(cr->resrec.name, name))
457 debugf("FindMatchingNSEC3ForName: NSEC3 record %s matched %##s", CRDisplayString(m, cr), name->c);
467 mDNSexport void InitializeAnonInfoForQuestion(mDNS *const m, CacheRecord **McastNSEC3Records, DNSQuestion *q)
469 CacheRecord *nsec3CR;
471 if (q->qtype != kDNSType_PTR)
474 nsec3CR = FindMatchingNSEC3ForName(m, McastNSEC3Records, &q->qname);
477 q->AnonInfo = AllocateAnonInfo(mDNSNULL, mDNSNULL, 0, &nsec3CR->resrec);
480 debugf("InitializeAnonInfoForQuestion: Found a matching NSEC3 record %s, for %##s (%s)",
481 RRDisplayString(m, q->AnonInfo->nsec3RR), q->qname.c, DNSTypeName(q->qtype));
483 ReleaseCacheRecord(m, nsec3CR);
487 mDNSexport void InitializeAnonInfoForCR(mDNS *const m, CacheRecord **McastNSEC3Records, CacheRecord *cr)
489 CacheRecord *nsec3CR;
491 if (!(*McastNSEC3Records))
494 // If already initialized or not a PTR type, we don't have to do anything
495 if (cr->resrec.AnonInfo || cr->resrec.rrtype != kDNSType_PTR)
498 nsec3CR = FindMatchingNSEC3ForName(m, McastNSEC3Records, cr->resrec.name);
501 cr->resrec.AnonInfo = AllocateAnonInfo(mDNSNULL, mDNSNULL, 0, &nsec3CR->resrec);
502 if (cr->resrec.AnonInfo)
504 debugf("InitializeAnonInfoForCR: Found a matching NSEC3 record %s, for %##s (%s)",
505 RRDisplayString(m, cr->resrec.AnonInfo->nsec3RR), cr->resrec.name->c,
506 DNSTypeName(cr->resrec.rrtype));
508 ReleaseCacheRecord(m, nsec3CR);
512 mDNSexport mDNSBool IdenticalAnonInfo(AnonymousInfo *a1, AnonymousInfo *a2)
514 // if a1 is NULL and a2 is not NULL AND vice-versa
515 // return false as there is a change.
516 if ((a1 != mDNSNULL) != (a2 != mDNSNULL))
519 // Both could be NULL or non-NULL
522 // The caller already verified that the owner name is the same.
523 // Check whether the RData is same.
524 if (!IdenticalSameNameRecord(a1->nsec3RR, a2->nsec3RR))
526 debugf("IdenticalAnonInfo: nsec3RR mismatch");
533 mDNSexport void CopyAnonInfoForCR(mDNS *const m, CacheRecord *crto, CacheRecord *crfrom)
535 AnonymousInfo *aifrom = crfrom->resrec.AnonInfo;
536 AnonymousInfo *aito = crto->resrec.AnonInfo;
545 crto->resrec.AnonInfo = aifrom;
547 crfrom->resrec.AnonInfo = mDNSNULL;
551 FreeAnonInfo(aifrom);
552 crfrom->resrec.AnonInfo = mDNSNULL;
556 #else // !ANONYMOUS_DISABLED
558 mDNSexport void ReInitAnonInfo(AnonymousInfo **si, const domainname *name)
564 mDNSexport AnonymousInfo * AllocateAnonInfo(const domainname *service, const mDNSu8 *AnonData, int len, const ResourceRecord *rr)
574 mDNSexport void FreeAnonInfo(AnonymousInfo *ai)
579 mDNSexport void SetAnonData(DNSQuestion *q, ResourceRecord *rr, mDNSBool ForQuestion)
586 mDNSexport int AnonInfoAnswersQuestion(const ResourceRecord *const rr, const DNSQuestion *const q)
594 mDNSexport void InitializeAnonInfoForQuestion(mDNS *const m, CacheRecord **McastNSEC3Records, DNSQuestion *q)
597 (void)McastNSEC3Records;
601 mDNSexport void InitializeAnonInfoForCR(mDNS *const m, CacheRecord **McastNSEC3Records, CacheRecord *cr)
604 (void)McastNSEC3Records;
608 mDNSexport void CopyAnonInfoForCR(mDNS *const m, CacheRecord *crto, CacheRecord *crfrom)
615 mDNSexport mDNSBool IdenticalAnonInfo(AnonymousInfo *a1, AnonymousInfo *a2)
623 #endif // !ANONYMOUS_DISABLED