mDNSexport CacheRecord *NSECRecordIsDelegation(mDNS *const m, domainname *name, mDNSu16 qtype)
{
CacheGroup *cg;
CacheRecord *cr;
mDNSu32 slot, namehash;
slot = HashSlot(name);
namehash = DomainNameHashValue(name);
cg = CacheGroupForName(m, (const mDNSu32)slot, namehash, name);
if (!cg)
{
LogDNSSEC("NSECRecordForName: cg NULL for %##s", name);
return mDNSNULL;
}
for (cr = cg->members; cr; cr = cr->next)
{
if (cr->resrec.RecordType == kDNSRecordTypePacketNegative && cr->resrec.rrtype == qtype)
{
CacheRecord *ncr;
for (ncr = cr->nsec; ncr; ncr = ncr->next)
{
if (ncr->resrec.rrtype == kDNSType_NSEC &&
SameDomainName(ncr->resrec.name, name))
{
// See the Insecure Delegation Proof section in dnssec-bis: DS bit and SOA bit
// should be absent
if (RRAssertsExistence(&ncr->resrec, kDNSType_SOA) ||
RRAssertsExistence(&ncr->resrec, kDNSType_DS))
{
LogDNSSEC("NSECRecordForName: found record %s for %##s (%s), but DS or SOA bit set", CRDisplayString(m, ncr), name,
DNSTypeName(qtype));
return mDNSNULL;
}
// Section 2.3 of RFC 4035 states that:
//
// Each owner name in the zone that has authoritative data or a delegation point NS RRset MUST
// have an NSEC resource record.
//
// So, if we have an NSEC record matching the question name with the NS bit set,
// then this is a delegation.
//
if (RRAssertsExistence(&ncr->resrec, kDNSType_NS))
{
LogDNSSEC("NSECRecordForName: found record %s for %##s (%s)", CRDisplayString(m, ncr), name, DNSTypeName(qtype));
return ncr;
}
else
{
LogDNSSEC("NSECRecordForName: found record %s for %##s (%s), but NS bit is not set", CRDisplayString(m, ncr), name,
DNSTypeName(qtype));
return mDNSNULL;
}
}
}
}
}
return mDNSNULL;
}
mDNSlocal CacheRecord *NSECParentForQuestion(mDNS *const m, DNSQuestion *q)
{
CacheGroup *cg;
CacheRecord *cr;
mDNSu32 slot;
mDNSu32 namehash;
slot = HashSlot(&q->qname);
namehash = DomainNameHashValue(&q->qname);
cg = CacheGroupForName(m, slot, namehash, &q->qname);
if (!cg)
{
LogDNSSEC("NSECParentForQuestion: Cannot find cg for %##s (%s)", q->qname.c, DNSTypeName(q->qtype));
return mDNSNULL;
}
for (cr = cg->members; cr; cr = cr->next)
if (SameNameRecordAnswersQuestion(&cr->resrec, q))
return cr;
return mDNSNULL;
}
mDNSexport CacheRecord *NSEC3RecordIsDelegation(mDNS *const m, domainname *name, mDNSu16 qtype)
{
CacheGroup *cg;
CacheRecord *cr;
CacheRecord *ncr;
mDNSu32 slot, namehash;
slot = HashSlot(name);
namehash = DomainNameHashValue(name);
cg = CacheGroupForName(m, (const mDNSu32)slot, namehash, name);
if (!cg)
{
LogDNSSEC("NSEC3RecordForName: cg NULL for %##s", name);
return mDNSNULL;
}
for (ncr = cg->members; ncr; ncr = ncr->next)
{
if (ncr->resrec.RecordType != kDNSRecordTypePacketNegative ||
ncr->resrec.rrtype != qtype)
{
continue;
}
for (cr = ncr->nsec; cr; cr = cr->next)
{
int hlen, b32len;
const mDNSu8 hashName[NSEC3_MAX_HASH_LEN];
const mDNSu8 b32Name[NSEC3_MAX_B32_LEN+1];
const RDataBody2 *const rdb = (RDataBody2 *)cr->resrec.rdata->u.data;
rdataNSEC3 *nsec3;
if (cr->resrec.rrtype != kDNSType_NSEC3)
continue;
nsec3 = (rdataNSEC3 *)rdb->data;
if (!NSEC3HashName(name, nsec3, mDNSNULL, 0, hashName, &hlen))
{
LogMsg("NSEC3RecordIsDelegation: NSEC3HashName failed for ##s", name->c);
return mDNSNULL;
}
b32len = baseEncode((char *)b32Name, sizeof(b32Name), (mDNSu8 *)hashName, hlen, ENC_BASE32);
if (!b32len)
{
LogMsg("NSEC3RecordIsDelegation: baseEncode of name %##s failed", name->c);
return mDNSNULL;
}
// Section 2.3 of RFC 4035 states that:
//
// Each owner name in the zone that has authoritative data or a delegation point NS RRset MUST
// have an NSEC resource record.
//
// This applies to NSEC3 record. So, if we have an NSEC3 record matching the question name with the
// NS bit set, then this is a delegation.
//
if (!NSEC3SameName(&cr->resrec.name->c[1], cr->resrec.name->c[0], (const mDNSu8 *)b32Name, b32len))
{
int bmaplen;
mDNSu8 *bmap;
LogDNSSEC("NSEC3RecordIsDelegation: CacheRecord %s matches name %##s, b32name %s", CRDisplayString(m, cr), name->c, b32Name);
NSEC3Parse(&cr->resrec, mDNSNULL, mDNSNULL, mDNSNULL, &bmaplen, &bmap);
// See the Insecure Delegation Proof section in dnssec-bis: DS bit and SOA bit
// should be absent
if (BitmapTypeCheck(bmap, bmaplen, kDNSType_SOA) ||
BitmapTypeCheck(bmap, bmaplen, kDNSType_DS))
{
LogDNSSEC("NSEC3RecordIsDelegation: CacheRecord %s has DS or SOA bit set, ignoring", CRDisplayString(m, cr));
return mDNSNULL;
}
if (BitmapTypeCheck(bmap, bmaplen, kDNSType_NS))
return cr;
else
return mDNSNULL;
}
// If opt-out is not set, then it does not cover any delegations
if (!(nsec3->flags & NSEC3_FLAGS_OPTOUT))
continue;
// Opt-out allows insecure delegations to exist without the NSEC3 RR at the
// hashed owner name (see RFC 5155 section 6.0).
if (NSEC3CoversName(m, cr, hashName, hlen, b32Name, b32len))
{
LogDNSSEC("NSEC3RecordIsDelegation: CacheRecord %s covers name %##s with optout", CRDisplayString(m, cr), name->c);
return cr;
}
}
}
return mDNSNULL;
}
