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plugin/file: run additional processing for CNAME/DNAME answers (#8337)

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externalLookup, which resolves the chase for ordinary CNAME, wildcard
CNAME, and DNAME answers, returned a nil additional section. So a chased
SRV/MX/SVCB/HTTPS answer with an in-bailiwick target was missing the
target's A/AAAA glue, unlike the direct path.

Run additionalProcessing at externalLookup's return points so all three
callers add the glue, and add ordinary-CNAME, wildcard-CNAME, and DNAME
regression cases.

Fixes #6628

Signed-off-by: Saleh <root@lr0.org>
This commit is contained in:
Saleh
2026-08-04 04:49:50 +03:00
committed by GitHub
parent 0fa6c66797
commit 097ef7ef91
2 changed files with 60 additions and 5 deletions
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13
plugin/file/lookup.go
View File

@@ -350,7 +350,10 @@ func (z *Zone) authority(do bool, result Result) []dns.RR {
return z.ns(do)
}
// externalLookup adds signatures and tries to resolve CNAMEs that point to external names.
// externalLookup adds signatures and tries to resolve CNAMEs that point to
// external names. It also runs additional-section processing on the resolved
// answer so in-bailiwick SRV/MX/SVCB/HTTPS targets get their A/AAAA glue, like
// the direct path.
func (z *Zone) externalLookup(ctx context.Context, state request.Request, tr *tree.Tree, elem *tree.Elem, rrs []dns.RR) ([]dns.RR, []dns.RR, []dns.RR, Result) {
qtype := state.QType()
do := state.Do()
@@ -369,7 +372,7 @@ func (z *Zone) externalLookup(ctx context.Context, state request.Request, tr *tr
if elem == nil || (qtype == dns.TypeNS || qtype == dns.TypeSOA && targetName == z.origin) {
lookupRRs, result := z.doLookup(ctx, state, targetName, qtype)
rrs = append(rrs, lookupRRs...)
return rrs, z.authority(do, result), nil, result
return rrs, z.authority(do, result), z.additionalProcessing(rrs, do), result
}
i := 0
@@ -392,12 +395,12 @@ Redo:
if elem == nil || (qtype == dns.TypeNS || qtype == dns.TypeSOA && targetName == z.origin) {
lookupRRs, result := z.doLookup(ctx, state, targetName, qtype)
rrs = append(rrs, lookupRRs...)
return rrs, z.authority(do, result), nil, result
return rrs, z.authority(do, result), z.additionalProcessing(rrs, do), result
}
i++
if i > 8 {
return rrs, z.ns(do), nil, Success
return rrs, z.ns(do), z.additionalProcessing(rrs, do), Success
}
goto Redo
@@ -414,7 +417,7 @@ Redo:
}
}
return rrs, z.ns(do), nil, Success
return rrs, z.ns(do), z.additionalProcessing(rrs, do), Success
}
// findDelegation returns the first zone cut between the zone apex and qname.

52
plugin/file/lookup_test.go
View File

@@ -408,6 +408,48 @@ var additionalTestCases = []test.Case{
test.AAAA("other.example.org. 1800 IN AAAA 2001:db8::20"),
},
},
{
// An ordinary CNAME chased to an SRV still needs the target's glue (#6628).
Qname: "cname-srv.example.org.", Qtype: dns.TypeSRV,
Answer: []dns.RR{
test.CNAME("cname-srv.example.org. 1800 IN CNAME srv.example.org."),
test.SRV("srv.example.org. 1800 IN SRV 10 50 8080 host.example.org."),
test.SRV("srv.example.org. 1800 IN SRV 20 50 8080 host.example.org."),
},
Ns: additionalAuth,
Extra: []dns.RR{
test.A("host.example.org. 1800 IN A 192.0.2.10"),
test.AAAA("host.example.org. 1800 IN AAAA 2001:db8::10"),
},
},
{
// A wildcard CNAME chased to an SRV.
Qname: "foo.wild.example.org.", Qtype: dns.TypeSRV,
Answer: []dns.RR{
test.CNAME("foo.wild.example.org. 1800 IN CNAME srv.example.org."),
test.SRV("srv.example.org. 1800 IN SRV 10 50 8080 host.example.org."),
test.SRV("srv.example.org. 1800 IN SRV 20 50 8080 host.example.org."),
},
Ns: additionalAuth,
Extra: []dns.RR{
test.A("host.example.org. 1800 IN A 192.0.2.10"),
test.AAAA("host.example.org. 1800 IN AAAA 2001:db8::10"),
},
},
{
// A DNAME substitution landing on an SRV (#6628).
Qname: "srv.dname.example.org.", Qtype: dns.TypeSRV,
Answer: []dns.RR{
test.DNAME("dname.example.org. 1800 IN DNAME dsub.example.org."),
test.CNAME("srv.dname.example.org. 1800 IN CNAME srv.dsub.example.org."),
test.SRV("srv.dsub.example.org. 1800 IN SRV 10 50 8080 host.example.org."),
},
Ns: additionalAuth,
Extra: []dns.RR{
test.A("host.example.org. 1800 IN A 192.0.2.10"),
test.AAAA("host.example.org. 1800 IN AAAA 2001:db8::10"),
},
},
}
func TestAdditionalSectionDeduplication(t *testing.T) {
@@ -504,4 +546,14 @@ mixed IN SRV 10 50 8080 host.example.org.
; Two MX records with distinct targets.
two IN MX 10 host.example.org.
IN MX 20 other.example.org.
; A CNAME resolving to an SRV: the ordinary-CNAME chase must still add glue.
cname-srv IN CNAME srv.example.org.
; A wildcard CNAME resolving to an SRV.
*.wild IN CNAME srv.example.org.
; A DNAME whose subtree holds an SRV: the DNAME chase must add glue too.
dname IN DNAME dsub.example.org.
srv.dsub IN SRV 10 50 8080 host.example.org.
`