aboutsummaryrefslogtreecommitdiff
diff options
context:
space:
mode:
Diffstat
-rw-r--r--middleware/file/dname.go44
-rw-r--r--middleware/file/dname_test.go159
-rw-r--r--middleware/file/lookup.go21
-rw-r--r--middleware/test/helpers.go3
4 files changed, 225 insertions, 2 deletions
diff --git a/middleware/file/dname.go b/middleware/file/dname.go
new file mode 100644
index 000000000..e4c29c77d
--- /dev/null
+++ b/middleware/file/dname.go
@@ -0,0 +1,44 @@
+package file
+
+import (
+ "strings"
+
+ "github.com/miekg/dns"
+)
+
+// substituteDNAME performs the DNAME substitution defined by RFC 6672,
+// assuming the QTYPE of the query is not DNAME. It returns an empty
+// string if there is no match.
+func substituteDNAME(qname, owner, target string) string {
+ if dns.IsSubDomain(owner, qname) && qname != owner {
+ labels := dns.SplitDomainName(qname)
+ labels = append(labels[0:len(labels)-dns.CountLabel(owner)], dns.SplitDomainName(target)...)
+
+ return strings.Join(labels, ".") + "."
+ }
+
+ return ""
+}
+
+// synthesizeCNAME returns a CNAME RR pointing to the resulting name of
+// the DNAME substitution. The owner name of the CNAME is the QNAME of
+// the query and the TTL is the same as the corresponding DNAME RR.
+//
+// It returns nil if the DNAME substitution has no match.
+func synthesizeCNAME(qname string, d *dns.DNAME) *dns.CNAME {
+ target := substituteDNAME(qname, d.Header().Name, d.Target)
+ if target == "" {
+ return nil
+ }
+
+ r := new(dns.CNAME)
+ r.Hdr = dns.RR_Header{
+ Name: qname,
+ Rrtype: dns.TypeCNAME,
+ Class: dns.ClassINET,
+ Ttl: d.Header().Ttl,
+ }
+ r.Target = target
+
+ return r
+}
diff --git a/middleware/file/dname_test.go b/middleware/file/dname_test.go
new file mode 100644
index 000000000..e26a1c29a
--- /dev/null
+++ b/middleware/file/dname_test.go
@@ -0,0 +1,159 @@
+package file
+
+import (
+ "sort"
+ "strings"
+ "testing"
+
+ "github.com/coredns/coredns/middleware/pkg/dnsrecorder"
+ "github.com/coredns/coredns/middleware/test"
+
+ "github.com/miekg/dns"
+ "golang.org/x/net/context"
+)
+
+// RFC 6672, Section 2.2. Assuming QTYPE != DNAME.
+var dnameSubstitutionTestCases = []struct {
+ qname string
+ owner string
+ target string
+ expected string
+}{
+ {"com.", "example.com.", "example.net.", ""},
+ {"example.com.", "example.com.", "example.net.", ""},
+ {"a.example.com.", "example.com.", "example.net.", "a.example.net."},
+ {"a.b.example.com.", "example.com.", "example.net.", "a.b.example.net."},
+ {"ab.example.com.", "b.example.com.", "example.net.", ""},
+ {"foo.example.com.", "example.com.", "example.net.", "foo.example.net."},
+ {"a.x.example.com.", "x.example.com.", "example.net.", "a.example.net."},
+ {"a.example.com.", "example.com.", "y.example.net.", "a.y.example.net."},
+ {"cyc.example.com.", "example.com.", "example.com.", "cyc.example.com."},
+ {"cyc.example.com.", "example.com.", "c.example.com.", "cyc.c.example.com."},
+ {"shortloop.x.x.", "x.", ".", "shortloop.x."},
+ {"shortloop.x.", "x.", ".", "shortloop."},
+}
+
+func TestDNAMESubstitution(t *testing.T) {
+ for i, tc := range dnameSubstitutionTestCases {
+ result := substituteDNAME(tc.qname, tc.owner, tc.target)
+ if result != tc.expected {
+ if result == "" {
+ result = "<no match>"
+ }
+
+ t.Errorf("Case %d: Expected %s -> %s, got %v", i, tc.qname, tc.expected, result)
+ return
+ }
+ }
+}
+
+var dnameTestCases = []test.Case{
+ {
+ Qname: "dname.miek.nl.", Qtype: dns.TypeDNAME,
+ Answer: []dns.RR{
+ test.DNAME("dname.miek.nl. 1800 IN DNAME test.miek.nl."),
+ },
+ Ns: miekAuth,
+ },
+ {
+ Qname: "dname.miek.nl.", Qtype: dns.TypeA,
+ Answer: []dns.RR{
+ test.A("dname.miek.nl. 1800 IN A 127.0.0.1"),
+ },
+ Ns: miekAuth,
+ },
+ {
+ Qname: "dname.miek.nl.", Qtype: dns.TypeMX,
+ Answer: []dns.RR{},
+ Ns: []dns.RR{
+ test.SOA("miek.nl. 1800 IN SOA linode.atoom.net. miek.miek.nl. 1282630057 14400 3600 604800 14400"),
+ },
+ },
+ {
+ Qname: "a.dname.miek.nl.", Qtype: dns.TypeA,
+ Answer: []dns.RR{
+ test.CNAME("a.dname.miek.nl. 1800 IN CNAME a.test.miek.nl."),
+ test.A("a.test.miek.nl. 1800 IN A 139.162.196.78"),
+ test.DNAME("dname.miek.nl. 1800 IN DNAME test.miek.nl."),
+ },
+ Ns: miekAuth,
+ },
+ {
+ Qname: "www.dname.miek.nl.", Qtype: dns.TypeA,
+ Answer: []dns.RR{
+ test.A("a.test.miek.nl. 1800 IN A 139.162.196.78"),
+ test.DNAME("dname.miek.nl. 1800 IN DNAME test.miek.nl."),
+ test.CNAME("www.dname.miek.nl. 1800 IN CNAME www.test.miek.nl."),
+ test.CNAME("www.test.miek.nl. 1800 IN CNAME a.test.miek.nl."),
+ },
+ Ns: miekAuth,
+ },
+}
+
+func TestLookupDNAME(t *testing.T) {
+ zone, err := Parse(strings.NewReader(dbMiekNLDNAME), testzone, "stdin")
+ if err != nil {
+ t.Fatalf("Expect no error when reading zone, got %q", err)
+ }
+
+ fm := File{Next: test.ErrorHandler(), Zones: Zones{Z: map[string]*Zone{testzone: zone}, Names: []string{testzone}}}
+ ctx := context.TODO()
+
+ for _, tc := range dnameTestCases {
+ m := tc.Msg()
+
+ rec := dnsrecorder.New(&test.ResponseWriter{})
+ _, err := fm.ServeDNS(ctx, rec, m)
+ if err != nil {
+ t.Errorf("Expected no error, got %v\n", err)
+ return
+ }
+
+ resp := rec.Msg
+ sort.Sort(test.RRSet(resp.Answer))
+ sort.Sort(test.RRSet(resp.Ns))
+ sort.Sort(test.RRSet(resp.Extra))
+
+ if !test.Header(t, tc, resp) {
+ t.Logf("%v\n", resp)
+ continue
+ }
+ if !test.Section(t, tc, test.Answer, resp.Answer) {
+ t.Logf("%v\n", resp)
+ }
+ if !test.Section(t, tc, test.Ns, resp.Ns) {
+ t.Logf("%v\n", resp)
+ }
+ if !test.Section(t, tc, test.Extra, resp.Extra) {
+ t.Logf("%v\n", resp)
+ }
+ }
+}
+
+const dbMiekNLDNAME = `
+$TTL 30M
+$ORIGIN miek.nl.
+@ IN SOA linode.atoom.net. miek.miek.nl. (
+ 1282630057 ; Serial
+ 4H ; Refresh
+ 1H ; Retry
+ 7D ; Expire
+ 4H ) ; Negative Cache TTL
+ IN NS linode.atoom.net.
+ IN NS ns-ext.nlnetlabs.nl.
+ IN NS omval.tednet.nl.
+ IN NS ext.ns.whyscream.net.
+
+test IN MX 1 aspmx.l.google.com.
+ IN MX 5 alt1.aspmx.l.google.com.
+ IN MX 5 alt2.aspmx.l.google.com.
+ IN MX 10 aspmx2.googlemail.com.
+ IN MX 10 aspmx3.googlemail.com.
+a.test IN A 139.162.196.78
+ IN AAAA 2a01:7e00::f03c:91ff:fef1:6735
+www.test IN CNAME a.test
+
+dname IN DNAME test
+dname IN A 127.0.0.1
+a.dname IN A 127.0.0.1
+`
diff --git a/middleware/file/lookup.go b/middleware/file/lookup.go
index 94ec0e726..2e95e42c7 100644
--- a/middleware/file/lookup.go
+++ b/middleware/file/lookup.go
@@ -63,7 +63,7 @@ func (z *Zone) Lookup(state request.Request, qname string) ([]dns.RR, []dns.RR,
// use the wildcard.
//
// Main for-loop handles delegation and finding or not finding the qname.
- // If found we check if it is a CNAME and do CNAME processing (DNAME should be added as well)
+ // If found we check if it is a CNAME/DNAME and do CNAME processing
// We also check if we have type and do a nodata resposne.
//
// If not found, we check the potential wildcard, and use that for further processing.
@@ -95,6 +95,24 @@ func (z *Zone) Lookup(state request.Request, qname string) ([]dns.RR, []dns.RR,
continue
}
+ // If we see DNAME records, we should return those.
+ if dnamerrs := elem.Types(dns.TypeDNAME); dnamerrs != nil {
+ // Only one DNAME is allowed per name. We just pick the first one.
+ dname := dnamerrs[0]
+ if cname := synthesizeCNAME(state.Name(), dname.(*dns.DNAME)); cname != nil {
+ answer, ns, extra, rcode := z.searchCNAME(state, elem, []dns.RR{cname})
+
+ // The relevant DNAME RR should be included in the answer section,
+ // if the DNAME is being employed as a substitution instruction.
+ answer = append([]dns.RR{dname}, answer...)
+
+ return answer, ns, extra, rcode
+ }
+ // The domain name that owns a DNAME record is allowed to have other RR types
+ // at that domain name, except those have restrictions on what they can coexist
+ // with (e.g. another DNAME). So there is nothing special left here.
+ }
+
// If we see NS records, it means the name as been delegated, and we should return the delegation.
if nsrrs := elem.Types(dns.TypeNS); nsrrs != nil {
glue := z.Glue(nsrrs, do)
@@ -122,7 +140,6 @@ func (z *Zone) Lookup(state request.Request, qname string) ([]dns.RR, []dns.RR,
// Found entire name.
if found && shot {
- // DNAME...?
if rrs := elem.Types(dns.TypeCNAME); len(rrs) > 0 && qtype != dns.TypeCNAME {
return z.searchCNAME(state, elem, rrs)
}
diff --git a/middleware/test/helpers.go b/middleware/test/helpers.go
index 339385a23..0ac329ec0 100644
--- a/middleware/test/helpers.go
+++ b/middleware/test/helpers.go
@@ -61,6 +61,9 @@ func AAAA(rr string) *dns.AAAA { r, _ := dns.NewRR(rr); return r.(*dns.AAAA) }
// CNAME returns a CNAME record from rr. It panics on errors.
func CNAME(rr string) *dns.CNAME { r, _ := dns.NewRR(rr); return r.(*dns.CNAME) }
+// DNAME returns a DNAME record from rr. It panics on errors.
+func DNAME(rr string) *dns.DNAME { r, _ := dns.NewRR(rr); return r.(*dns.DNAME) }
+
// SRV returns a SRV record from rr. It panics on errors.
func SRV(rr string) *dns.SRV { r, _ := dns.NewRR(rr); return r.(*dns.SRV) }
generated by cgit v1.2.3 (git 2.39.1) at 2025-08-05 19:15:47 +0000