mDNSexport void InitializeAnonInfoForQuestion(mDNS *const m, CacheRecord **McastNSEC3Records, DNSQuestion *q)
{
CacheRecord *nsec3CR;
if (q->qtype != kDNSType_PTR)
return;
nsec3CR = FindMatchingNSEC3ForName(m, McastNSEC3Records, &q->qname);
if (nsec3CR)
{
q->AnonInfo = AllocateAnonInfo(mDNSNULL, mDNSNULL, 0, &nsec3CR->resrec);
if (q->AnonInfo)
{
debugf("InitializeAnonInfoForQuestion: Found a matching NSEC3 record %s, for %##s (%s)",
RRDisplayString(m, q->AnonInfo->nsec3RR), q->qname.c, DNSTypeName(q->qtype));
}
ReleaseCacheRecord(m, nsec3CR);
}
}
mDNSlocal mDNSBool NSECNoWildcard(mDNS *const m, ResourceRecord *rr, domainname *qname, mDNSu16 qtype)
{
const domainname *ce;
domainname wild;
// If the query name is c.x.w.example and if the name does not exist, we should get
// get a nsec back that looks something like this:
//
// w.example NSEC a.w.example
//
// First, we need to get the closest encloser which in this case is w.example. Wild
// card synthesis works by finding the closest encloser first and then look for
// a "*" label (assuming * label does not appear in the question). If it does not
// exists, it would return the NSEC at that name. And the wildcard name at the
// closest encloser "*.w.example" would be covered by such an NSEC. (Appending "*"
// makes it bigger than w.example and "* is smaller than "a" for the above NSEC)
//
ce = NSECClosestEncloser(rr, qname);
if (!ce) { LogMsg("NSECNoWildcard: No closest encloser for rr %s, qname %##s (%s)", qname->c, DNSTypeName(qtype)); return mDNSfalse; }
wild.c[0] = 1;
wild.c[1] = '*';
wild.c[2] = 0;
if (!AppendDomainName(&wild, ce))
{
LogMsg("NSECNoWildcard: ERROR!! Can't append domainname closest encloser name %##s, qname %##s (%s)", ce->c, qname->c, DNSTypeName(qtype));
return mDNSfalse;
}
if (NSECNameExists(m, rr, &wild, qtype) != 0)
{
LogDNSSEC("NSECNoWildcard: Wildcard name %##s exists or not valid qname %##s (%s)", wild.c, qname->c, DNSTypeName(qtype));
return mDNSfalse;
}
LogDNSSEC("NSECNoWildcard: Wildcard name %##s does not exist for record %s, qname %##s (%s)", wild.c,
RRDisplayString(m, rr), qname->c, DNSTypeName(qtype));
return mDNStrue;
}
mDNSexport void InitializeAnonInfoForCR(mDNS *const m, CacheRecord **McastNSEC3Records, CacheRecord *cr)
{
CacheRecord *nsec3CR;
if (!(*McastNSEC3Records))
return;
// If already initialized or not a PTR type, we don't have to do anything
if (cr->resrec.AnonInfo || cr->resrec.rrtype != kDNSType_PTR)
return;
nsec3CR = FindMatchingNSEC3ForName(m, McastNSEC3Records, cr->resrec.name);
if (nsec3CR)
{
cr->resrec.AnonInfo = AllocateAnonInfo(mDNSNULL, mDNSNULL, 0, &nsec3CR->resrec);
if (cr->resrec.AnonInfo)
{
debugf("InitializeAnonInfoForCR: Found a matching NSEC3 record %s, for %##s (%s)",
RRDisplayString(m, cr->resrec.AnonInfo->nsec3RR), cr->resrec.name->c,
DNSTypeName(cr->resrec.rrtype));
}
ReleaseCacheRecord(m, nsec3CR);
}
}
mDNSlocal void DNSSECProbeCallback(mDNS *const m, DNSQuestion *question, const ResourceRecord *const answer, QC_result AddRecord)
{
if (!AddRecord)
return;
mDNS_Lock(m);
if ((m->timenow - question->StopTime) >= 0)
{
mDNS_Unlock(m);
LogDNSSEC("DNSSECProbeCallback: Question %##s (%s) timed out", question->qname.c, DNSTypeName(question->qtype));
mDNS_StopQuery(m, question);
return;
}
mDNS_Unlock(m);
// Wait till we get the DNSSEC results. If we get a negative response e.g., no DNS servers, the
// question will be restarted by the core and we should have the DNSSEC results eventually.
if (AddRecord != QC_dnssec)
{
LogDNSSEC("DNSSECProbeCallback: Question %##s (%s)", question->qname.c, DNSTypeName(question->qtype), RRDisplayString(m, answer));
return;
}
LogDNSSEC("DNSSECProbeCallback: Question %##s (%s), DNSSEC status %s", question->qname.c, DNSTypeName(question->qtype),
DNSSECStatusName(question->ValidationStatus));
mDNS_StopQuery(m, question);
}
// We get a NXDOMAIN error with no records in answer section. This proves
// that qname does not exist.
mDNSlocal void NameErrorProof(mDNS *const m, DNSSECVerifier *dv, CacheRecord *ncr)
{
CacheRecord **rp;
ResourceRecord *nsec_wild = mDNSNULL;
ResourceRecord *nsec_noname = mDNSNULL;
mStatus status;
// NXDOMAIN Error. We need to prove that the qname does not exist and there
// is no wildcard that can be used to answer the question.
rp = &(ncr->nsec);
while (*rp)
{
if ((*rp)->resrec.rrtype == kDNSType_NSEC)
{
CacheRecord *cr = *rp;
if (!NSECNameExists(m, &cr->resrec, &dv->q.qname, dv->q.qtype))
{
LogDNSSEC("NameErrorProof: NSEC %s proves name does not exist for %##s (%s)",
RRDisplayString(m, &(*rp)->resrec), dv->q.qname.c, DNSTypeName(dv->q.qtype));
// If we have a wildcard, then we should check to see if the closest
// encloser is the same as the wildcard.
dv->flags |= NSEC_PROVES_NONAME_EXISTS;
nsec_noname = &cr->resrec;
}
if (NSECNoWildcard(m, &cr->resrec, &dv->q.qname, dv->q.qtype))
{
dv->flags |= WILDCARD_PROVES_NONAME_EXISTS;
nsec_wild = &cr->resrec;
LogDNSSEC("NameErrorProof: NSEC %s proves wildcard cannot answer question for %##s (%s)",
RRDisplayString(m, &(*rp)->resrec), dv->q.qname.c, DNSTypeName(dv->q.qtype));
}
}
rp=&(*rp)->next;
}
if (!nsec_noname || !nsec_wild)
{
LogMsg("NameErrorProof: Proof failed for %##s (%s) noname %p, wild %p", dv->q.qname.c, DNSTypeName(dv->q.qtype), nsec_noname, nsec_wild);
goto error;
}
// First verify wildcard NSEC and then when we are done, we will verify the noname nsec.
// Sometimes a single NSEC can prove both that the "qname" does not exist and a wildcard
// could not have produced qname. These are a few examples where this can happen.
//
// 1. If the zone is example.com and you look up *.example.com and if there are no wildcards,
// you will get a NSEC back "example.com NSEC a.example.com". This proves that both the
// name does not exist and *.example.com also does not exist
//
// 2. If the zone is example.com and it has a record like this:
//
// example.com NSEC d.example.com
//
// any name you lookup in between like a.example.com,b.example.com etc. you will get a single
// NSEC back. In that case we just have to verify only once.
//
if (nsec_wild != nsec_noname)
{
RRVerifier *r = AllocateRRVerifier(nsec_noname, &status);
if (!r) goto error;
dv->pendingNSEC = r;
LogDNSSEC("NoDataProof: Verifying wild %s", RRDisplayString(m, nsec_wild));
VerifyNSEC(m, nsec_wild, mDNSNULL, dv, ncr, NameErrorNSECCallback);
}
else
{
LogDNSSEC("NoDataProof: Verifying only one %s", RRDisplayString(m, nsec_wild));
VerifyNSEC(m, nsec_wild, mDNSNULL, dv, ncr, mDNSNULL);
}
return;
error:
dv->DVCallback(m, dv, DNSSEC_Bogus);
}
// We get a NODATA error with no records in answer section. This proves
// that qname does not exist.
mDNSlocal void NoDataProof(mDNS *const m, DNSSECVerifier *dv, CacheRecord *ncr)
{
CacheRecord **rp;
domainname *wildcard = mDNSNULL;
const domainname *ce = mDNSNULL;
ResourceRecord *nsec_wild = mDNSNULL;
ResourceRecord *nsec_noname = mDNSNULL;
// NODATA Error could mean two things. The name exists with no type or there is a
// wildcard that matches the name but no type. This is done by NSECNoDataError.
//
// If it is the case of wildcard, there are two NSECs. One is the wildcard NSEC and
// the other NSEC to prove that there is no other closer match.
wildcard = mDNSNULL;
rp = &(ncr->nsec);
while (*rp)
{
if ((*rp)->resrec.rrtype == kDNSType_NSEC)
{
CacheRecord *cr = *rp;
if (NSECNoDataError(m, &cr->resrec, &dv->q.qname, dv->q.qtype, &wildcard))
{
if (wildcard)
{
dv->flags |= WILDCARD_PROVES_NONAME_EXISTS;
LogDNSSEC("NoDataProof: NSEC %s proves NODATA error for %##s (%s)",
RRDisplayString(m, &(*rp)->resrec), dv->q.qname.c, DNSTypeName(dv->q.qtype));
}
else
{
dv->flags |= NSEC_PROVES_NOTYPE_EXISTS;
LogDNSSEC("NoDataProof: NSEC %s proves NOTYPE error for %##s (%s)",
RRDisplayString(m, &(*rp)->resrec), dv->q.qname.c, DNSTypeName(dv->q.qtype));
}
nsec_wild = &cr->resrec;
}
if (!NSECNameExists(m, &cr->resrec, &dv->q.qname, dv->q.qtype))
{
LogDNSSEC("NoDataProof: NSEC %s proves that name %##s (%s) does not exist",
RRDisplayString(m, &(*rp)->resrec), dv->q.qname.c, DNSTypeName(dv->q.qtype));
// If we have a wildcard, then we should check to see if the closest
// encloser is the same as the wildcard.
ce = NSECClosestEncloser(&cr->resrec, &dv->q.qname);
dv->flags |= NSEC_PROVES_NONAME_EXISTS;
nsec_noname = &cr->resrec;
}
}
rp=&(*rp)->next;
}
if (!nsec_noname && !nsec_wild)
{
LogDNSSEC("NoDataProof: No valid NSECs for %##s (%s)", dv->q.qname.c, DNSTypeName(dv->q.qtype));
goto error;
}
// If the type exists, then we have to verify just that NSEC
if (!(dv->flags & NSEC_PROVES_NOTYPE_EXISTS))
{
// If we have a wildcard, then we should have a "ce" which matches the wildcard
// If we don't have a wildcard, then we should have proven that the name does not
// exist which means we would have set the "ce".
if (wildcard && !ce)
{
LogMsg("NoDataProof: Cannot prove that the name %##s (%s) does not exist", dv->q.qname.c, DNSTypeName(dv->q.qtype));
goto error;
}
if (wildcard && !SameDomainName(wildcard, ce))
{
LogMsg("NoDataProof: wildcard %##s does not match closest encloser %##s", wildcard->c, ce->c);
goto error;
}
// If a single NSEC can prove both, then we just have validate that one NSEC.
if (nsec_wild == nsec_noname)
{
nsec_noname = mDNSNULL;
dv->flags &= ~NSEC_PROVES_NONAME_EXISTS;
}
}
if ((dv->flags & (WILDCARD_PROVES_NONAME_EXISTS|NSEC_PROVES_NONAME_EXISTS)) ==
(WILDCARD_PROVES_NONAME_EXISTS|NSEC_PROVES_NONAME_EXISTS))
{
mStatus status;
RRVerifier *r = AllocateRRVerifier(nsec_noname, &status);
if (!r) goto error;
// First verify wildcard NSEC and then when we are done, we
// will verify the noname nsec
dv->pendingNSEC = r;
LogDNSSEC("NoDataProof: Verifying wild and noname %s", RRDisplayString(m, nsec_wild));
VerifyNSEC(m, nsec_wild, mDNSNULL, dv, ncr, NoDataNSECCallback);
}
else if ((dv->flags & WILDCARD_PROVES_NONAME_EXISTS) ||
(dv->flags & NSEC_PROVES_NOTYPE_EXISTS))
{
LogDNSSEC("NoDataProof: Verifying wild %s", RRDisplayString(m, nsec_wild));
VerifyNSEC(m, nsec_wild, mDNSNULL, dv, ncr, mDNSNULL);
}
else if (dv->flags & NSEC_PROVES_NONAME_EXISTS)
{
LogDNSSEC("NoDataProof: Verifying noname %s", RRDisplayString(m, nsec_noname));
VerifyNSEC(m, nsec_noname, mDNSNULL, dv, ncr, mDNSNULL);
}
return;
error:
LogDNSSEC("NoDataProof: Error return");
dv->DVCallback(m, dv, DNSSEC_Bogus);
}
// We have a NSEC. Need to see if it proves that NODATA exists for the given name. Note that this
// function does not prove anything as proof may require more than one NSEC and this function
// processes only one NSEC at a time.
//
// Returns mDNSfalse if the NSEC does not prove the NODATA error
// Returns mDNStrue if the NSEC proves the NODATA error
//
mDNSlocal mDNSBool NSECNoDataError(mDNS *const m, ResourceRecord *rr, domainname *name, mDNSu16 qtype, domainname **wildcard)
{
const domainname *oname = rr->name; // owner name
if (wildcard) *wildcard = mDNSNULL;
// RFC 4035
//
// section 3.1.3.1 : Name matches. Prove that the type does not exist and also CNAME is
// not set as in that case CNAME should have been returned ( CNAME part is mentioned in
// section 4.3 of dnssec-bis-updates.) Without the CNAME check, a positive response can
// be converted to a NODATA/NOERROR response.
//
// section 3.1.3.4 : No exact match for the name but there is a wildcard that could match
// the name but not the type. There are two NSECs in this case. One of them is a wildcard
// NSEC and another NSEC proving that the qname does not exist. We are called with one
// NSEC at a time. We return what we matched and the caller should decide whether all
// conditions are met for the proof.
if (SameDomainName(oname, name))
{
mDNSBool soa = RRAssertsExistence(rr, kDNSType_SOA);
mDNSBool ns = RRAssertsExistence(rr, kDNSType_NS);
if (qtype != kDNSType_DS)
{
// For non-DS type questions, we don't want to use the parent side records to
// answer it
if (ns && !soa)
{
LogDNSSEC("NSECNoDataError: Parent side NSEC %s, can't use for child qname %##s (%s)",
RRDisplayString(m, rr), name->c, DNSTypeName(qtype));
return mDNSfalse;
}
}
else
{
if (soa)
{
LogDNSSEC("NSECNoDataError: Child side NSEC %s, can't use for parent qname %##s (%s)",
RRDisplayString(m, rr), name->c, DNSTypeName(qtype));
return mDNSfalse;
}
}
if (RRAssertsExistence(rr, qtype) || RRAssertsExistence(rr, kDNSType_CNAME))
{
LogMsg("NSECNoDataError: ERROR!! qtype %s exists in %s", DNSTypeName(qtype), RRDisplayString(m, rr));
return mDNSfalse;
}
LogDNSSEC("NSECNoDataError: qype %s does not exist in %s", DNSTypeName(qtype), RRDisplayString(m, rr));
return mDNStrue;
}
else
{
// Name does not exist. Before we check for a wildcard match, make sure that
// this is not an ENT.
if (NSECAnswersENT(rr, name))
{
LogDNSSEC("NSECNoDataError: name %##s exists %s", name->c, RRDisplayString(m, rr));
return mDNSfalse;
}
// Wildcard check. If this is a wildcard NSEC, then check to see if we could
// have answered the question using this wildcard and it should not have the
// "qtype" passed in with its bitmap.
//
// See RFC 4592, on how wildcards are used to synthesize answers. Find the
// closest encloser and the qname should be a subdomain i.e if the wildcard
// is *.x.example, x.example is the closest encloser and the qname should be
// a subdomain e.g., y.x.example or z.y.x.example and so on.
if (oname->c[0] == 1 && oname->c[1] == '*')
{
int r, s;
const domainname *ce = SkipLeadingLabels(oname, 1);
r = DNSSECCanonicalOrder(name, ce, &s);
if (s)
{
if (RRAssertsExistence(rr, qtype) || RRAssertsExistence(rr, kDNSType_CNAME))
{
LogMsg("NSECNoDataError: ERROR!! qtype %s exists in wildcard %s", DNSTypeName(qtype), RRDisplayString(m, rr));
return mDNSfalse;
}
if (qtype == kDNSType_DS && RRAssertsExistence(rr, kDNSType_SOA))
{
LogDNSSEC("NSECNoDataError: Child side wildcard NSEC %s, can't use for parent qname %##s (%s)",
RRDisplayString(m, rr), name->c, DNSTypeName(qtype));
return mDNSfalse;
}
else if (qtype != kDNSType_DS && RRAssertsNonexistence(rr, kDNSType_SOA) &&
RRAssertsExistence(rr, kDNSType_NS))
{
// Don't use the parent side record for this
LogDNSSEC("NSECNoDataError: Parent side wildcard NSEC %s, can't use for child qname %##s (%s)",
RRDisplayString(m, rr), name->c, DNSTypeName(qtype));
return mDNSfalse;
}
*wildcard = (domainname *)ce;
LogDNSSEC("NSECNoDataError: qtype %s does not exist in wildcard %s", DNSTypeName(qtype), RRDisplayString(m, rr));
return mDNStrue;
}
}
return mDNSfalse;
}
}
// Assumption: NSEC has been validated outside of this function
//
// Does the name exist given the name and NSEC rr ?
//
// Returns -1 if it is an inappropriate nsec
// Returns 1 if the name exists
// Returns 0 if the name does not exist
//
mDNSlocal int NSECNameExists(mDNS *const m, ResourceRecord *rr, domainname *name, mDNSu16 qtype)
{
const RDataBody2 *const rdb = (RDataBody2 *)rr->rdata->u.data;
const domainname *nxt = (const domainname *)&rdb->data;
const domainname *oname = rr->name; // owner name
int ret1, subdomain1;
int ret2, subdomain2;
int ret3, subdomain3;
ret1 = DNSSECCanonicalOrder(oname, name, &subdomain1);
if (ret1 > 0)
{
LogDNSSEC("NSECNameExists: owner name %##s is bigger than name %##s", oname->c, name->c);
return -1;
}
// Section 4.1 of draft-ietf-dnsext-dnssec-bis-updates-14:
//
// Ancestor delegation NSEC or NSEC3 RRs MUST NOT be used to assume non-
// existence of any RRs below that zone cut, which include all RRs at
// that (original) owner name other than DS RRs, and all RRs below that
// owner name regardless of type.
//
// This also implies that we can't use the child side NSEC for DS question.
if (!ret1)
{
mDNSBool soa = RRAssertsExistence(rr, kDNSType_SOA);
mDNSBool ns = RRAssertsExistence(rr, kDNSType_NS);
// We are here because the owner name is the same as "name". Make sure the
// NSEC has the right NS and SOA bits set.
if (qtype != kDNSType_DS && ns && !soa)
{
LogDNSSEC("NSECNameExists: Parent side NSEC %s can't be used for question %##s (%s)",
RRDisplayString(m, rr), name->c, DNSTypeName(qtype));
return -1;
}
else if (qtype == kDNSType_DS && soa)
{
LogDNSSEC("NSECNameExists: Child side NSEC %s can't be used for question %##s (%s)",
RRDisplayString(m, rr), name->c, DNSTypeName(qtype));
return -1;
}
LogDNSSEC("NSECNameExists: owner name %##s is same as name %##s", oname->c, name->c);
return 1;
}
// If the name is a.b.com and NSEC's owner name is b.com i.e., a subdomain
// and nsec comes from the parent (NS is set and SOA is not set), then this
// NSEC can't be used for names below the owner name.
//
// Similarly if DNAME is set, we can't use it here. See RFC2672-bis-dname
// appendix.
if (subdomain1 && (RRAssertsExistence(rr, kDNSType_DNAME) ||
(RRAssertsNonexistence(rr, kDNSType_SOA) && RRAssertsExistence(rr, kDNSType_NS))))
{
LogDNSSEC("NSECNameExists: NSEC %s comes from the parent, can't use it here",
RRDisplayString(m, rr));
return -1;
}
// At this stage, we know that name is greater than the owner name and
// the nsec is not from the parent side.
//
// Compare with the next field in the nsec.
//
ret2 = DNSSECCanonicalOrder(name, nxt, &subdomain2);
// Exact match with the nsec next name
if (!ret2)
{
LogDNSSEC("NSECNameExists: name %##s is same as nxt name %##s", name->c, nxt->c);
return 1;
}
ret3 = DNSSECCanonicalOrder(oname, nxt, &subdomain3);
if (!ret3)
{
// Pathological case of a single name in the domain. This means only the
// apex of the zone itself exists. Nothing below it. "subdomain2" indicates
// that name is a subdmain of "next" and hence below the zone.
if (subdomain2)
{
LogDNSSEC("NSECNameExists: owner name %##s subdomain of nxt name %##s", oname->c, nxt->c);
return 0;
}
else
{
LogDNSSEC("NSECNameExists: Single name in zone, owner name %##s is same as nxt name %##s", oname->c, nxt->c);
return -1;
}
}
if (ret3 < 0)
{
// Regular NSEC in the zone. Make sure that the "name" lies within
// oname and next. oname < name and name < next
if (ret1 < 0 && ret2 < 0)
{
LogDNSSEC("NSECNameExists: Normal NSEC name %##s lies within owner %##s and nxt name %##s",
name->c, oname->c, nxt->c);
return 0;
}
else
{
LogDNSSEC("NSECNameExists: Normal NSEC name %##s does not lie within owner %##s and nxt name %##s",
name->c, oname->c, nxt->c);
return -1;
}
}
else
{
// Last NSEC in the zone. The "next" is pointing to the apex. All names
// should be a subdomain of that and the name should be bigger than
// oname
if (ret1 < 0 && subdomain2)
{
LogDNSSEC("NSECNameExists: Last NSEC name %##s lies within owner %##s and nxt name %##s",
name->c, oname->c, nxt->c);
return 0;
}
else
{
LogDNSSEC("NSECNameExists: Last NSEC name %##s does not lie within owner %##s and nxt name %##s",
name->c, oname->c, nxt->c);
return -1;
}
}
LogDNSSEC("NSECNameExists: NSEC %s did not match any case", RRDisplayString(m, rr));
return -1;
}
// returns -1 if the caller should ignore the result
// returns 1 if the record answers the question
// returns 0 if the record does not answer the question
mDNSexport int AnonInfoAnswersQuestion(const ResourceRecord *const rr, const DNSQuestion *const q)
{
mDNSexport mDNS mDNSStorage;
ResourceRecord *nsec3RR;
int i;
AnonymousInfo *qai, *rai;
mDNSu8 *AnonData;
int AnonDataLen;
rdataNSEC3 *nsec3;
int hlen;
const mDNSu8 hashName[NSEC3_MAX_HASH_LEN];
int nxtLength;
mDNSu8 *nxtName;
debugf("AnonInfoAnswersQuestion: question qname %##s", q->qname.c);
// Currently only PTR records can have anonymous information
if (q->qtype != kDNSType_PTR)
{
return -1;
}
// We allow anonymous questions to be answered by both normal services (without the
// anonymous information) and anonymous services that are part of the same set. And
// normal questions discover normal services and all anonymous services.
//
// The three cases have been enumerated clearly even though they all behave the
// same way.
if (!q->AnonInfo)
{
debugf("AnonInfoAnswersQuestion: not a anonymous type question");
if (!rr->AnonInfo)
{
// case 1
return -1;
}
else
{
// case 2
debugf("AnonInfoAnswersQuestion: Question %##s not answered using anonymous record %##s", q->qname.c, rr->name->c);
return -1;
}
}
else
{
// case 3
if (!rr->AnonInfo)
{
debugf("AnonInfoAnswersQuestion: not a anonymous type record");
return -1;
}
}
// case 4: We have the anonymous information both in the question and the record. We need
// two sets of information to validate.
//
// 1) Anonymous data that identifies the set/group
// 2) NSEC3 record that contains the hash and the salt
//
// If the question is a remote one, it does not have the anonymous information to validate (just
// the NSEC3 record) and hence the anonymous data should come from the local resource record. If the
// question is local, it can come from either of them and if there is a mismatch between the
// question and record, it won't validate.
qai = q->AnonInfo;
rai = rr->AnonInfo;
if (qai->AnonData && rai->AnonData)
{
// Before a cache record is created, if there is a matching question i.e., part
// of the same set, then when the cache is created we also set the anonymous
// information. Otherwise, the cache record contains just the NSEC3 record and we
// won't be here for that case.
//
// It is also possible that a local question is matched against the local AuthRecord
// as that is also the case for which the AnonData would be non-NULL for both.
// We match questions against AuthRecords (rather than the cache) for LocalOnly case and
// to see whether a .local query should be suppressed or not. The latter never happens
// because PTR queries are never suppressed.
// If they don't belong to the same anonymous set, then no point in validating.
if ((qai->AnonDataLen != rai->AnonDataLen) ||
mDNSPlatformMemCmp(qai->AnonData, rai->AnonData, qai->AnonDataLen) != 0)
{
debugf("AnonInfoAnswersQuestion: AnonData mis-match for record %s question %##s ",
RRDisplayString(&mDNSStorage, rr), q->qname.c);
return 0;
}
// AnonData matches i.e they belong to the same group and the same service.
LogInfo("AnonInfoAnswersQuestion: Answering qname %##s, rname %##s, without validation", q->qname.c,
rr->name->c);
return 1;
}
else
{
debugf("AnonInfoAnswersQuestion: question %p, record %p", qai->AnonData, rai->AnonData);
}
if (qai->AnonData)
{
// If there is AnonData, then this is a local question. The
// NSEC3 RR comes from the resource record which could be part
// of the cache or local auth record. The cache entry could
// be from a remote host or created when we heard our own
// announcements. In any case, we use that to see if it matches
// the question.
AnonData = qai->AnonData;
AnonDataLen = qai->AnonDataLen;
nsec3RR = rai->nsec3RR;
}
else
{
// Remote question or hearing our own question back
AnonData = rai->AnonData;
AnonDataLen = rai->AnonDataLen;
nsec3RR = qai->nsec3RR;
}
if (!AnonData || !nsec3RR)
{
// AnonData can be NULL for the cache entry and if we are hearing our own question back, AnonData is NULL for
// that too and we can end up here for that case.
debugf("AnonInfoAnswersQuestion: AnonData %p or nsec3RR %p, NULL for question %##s, record %s", AnonData, nsec3RR,
q->qname.c, RRDisplayString(&mDNSStorage, rr));
return 0;
}
debugf("AnonInfoAnswersQuestion: Validating question %##s, ResourceRecord %s", q->qname.c, RRDisplayString(&mDNSStorage, nsec3RR));
nsec3 = (rdataNSEC3 *)nsec3RR->rdata->u.data;
if (!NSEC3HashName(nsec3RR->name, nsec3, AnonData, AnonDataLen, hashName, &hlen))
{
LogMsg("AnonInfoAnswersQuestion: NSEC3HashName failed for ##s", nsec3RR->name->c);
return mDNSfalse;
}
if (hlen != SHA1_HASH_LENGTH)
{
LogMsg("AnonInfoAnswersQuestion: hlen wrong %d", hlen);
return mDNSfalse;
}
NSEC3Parse(nsec3RR, mDNSNULL, &nxtLength, &nxtName, mDNSNULL, mDNSNULL);
if (hlen != nxtLength)
{
LogMsg("AnonInfoAnswersQuestion: ERROR!! hlen %d not same as nxtLength %d", hlen, nxtLength);
return mDNSfalse;
}
for (i = 0; i < nxtLength; i++)
{
if (nxtName[i] != hashName[i])
{
debugf("AnonInfoAnswersQuestion: mismatch output %x, digest %x, i %d", nxtName[i+1], hashName[i], i);
return 0;
}
}
LogInfo("AnonInfoAnswersQuestion: ResourceRecord %s matched question %##s (%s)", RRDisplayString(&mDNSStorage, nsec3RR), q->qname.c, DNSTypeName(q->qtype));
return 1;
}