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middleware/file: Add CNAME chain support (#400)

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Up till now we would only chase 1 CNAME. Spec requires we will chase
all. This PR add support for this.  Up to 8 CNAMEs are chased (this
could be longer, by just checking for cycles, but 8 seems enough for
now).

Also add RRSIG of the first CNAME for DNSSEC.
This commit is contained in:
Miek Gieben
2016-11-09 10:02:26 +00:00
committed by GitHub
parent 6abbe231e5
commit 4ef53081c5
4 changed files with 157 additions and 16 deletions
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66
middleware/file/lookup.go
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@@ -118,8 +118,9 @@ func (z *Zone) Lookup(qname string, qtype uint16, do bool) ([]dns.RR, []dns.RR,
// Found entire name.
if found && shot {
if rrs := elem.Types(dns.TypeCNAME, qname); len(rrs) > 0 {
return z.searchCNAME(rrs, qtype, do)
// DNAME...
if rrs := elem.Types(dns.TypeCNAME); len(rrs) > 0 && qtype != dns.TypeCNAME {
return z.searchCNAME(elem, rrs, qtype, do)
}
rrs := elem.Types(qtype, qname)
@@ -151,7 +152,7 @@ func (z *Zone) Lookup(qname string, qtype uint16, do bool) ([]dns.RR, []dns.RR,
auth := []dns.RR{}
if rrs := wildElem.Types(dns.TypeCNAME, qname); len(rrs) > 0 {
return z.searchCNAME(rrs, qtype, do)
return z.searchCNAME(wildElem, rrs, qtype, do)
}
rrs := wildElem.Types(qtype, qname)
@@ -250,22 +251,61 @@ func (z *Zone) ns(do bool) []dns.RR {
return z.Apex.NS
}
func (z *Zone) searchCNAME(rrs []dns.RR, qtype uint16, do bool) ([]dns.RR, []dns.RR, []dns.RR, Result) {
elem, _ := z.Tree.Search(rrs[0].(*dns.CNAME).Target)
func (z *Zone) searchCNAME(elem *tree.Elem, rrs []dns.RR, qtype uint16, do bool) ([]dns.RR, []dns.RR, []dns.RR, Result) {
if do {
sigs := elem.Types(dns.TypeRRSIG)
sigs = signatureForSubType(sigs, dns.TypeCNAME)
if len(sigs) > 0 {
rrs = append(rrs, sigs...)
}
}
elem, _ = z.Tree.Search(rrs[0].(*dns.CNAME).Target)
if elem == nil {
return rrs, nil, nil, Success
}
// RECURSIVE SEARCH, up to 8 deep. Also: tests.
i := 0
Redo:
cname := elem.Types(dns.TypeCNAME)
if len(cname) > 0 {
rrs = append(rrs, cname...)
if do {
sigs := elem.Types(dns.TypeRRSIG)
sigs = signatureForSubType(sigs, dns.TypeCNAME)
if len(sigs) > 0 {
rrs = append(rrs, sigs...)
}
}
elem, _ = z.Tree.Search(cname[0].(*dns.CNAME).Target)
if elem == nil {
return rrs, nil, nil, Success
}
i++
if i > maxChain {
return rrs, nil, nil, Success
}
goto Redo
}
targets := cnameForType(elem.All(), qtype)
if do {
sigs := elem.Types(dns.TypeRRSIG)
sigs = signatureForSubType(sigs, qtype)
if len(sigs) > 0 {
targets = append(targets, sigs...)
if len(targets) > 0 {
rrs = append(rrs, targets...)
if do {
sigs := elem.Types(dns.TypeRRSIG)
sigs = signatureForSubType(sigs, qtype)
if len(sigs) > 0 {
rrs = append(rrs, sigs...)
}
}
}
return append(rrs, targets...), nil, nil, Success
return rrs, nil, nil, Success
}
func cnameForType(targets []dns.RR, origQtype uint16) []dns.RR {
@@ -317,3 +357,5 @@ func (z *Zone) searchGlue(name string) []dns.RR {
}
return glue
}
const maxChain = 8