plugin/template: fix CNAME upstream handling (#1886)

test/template_upstream_test.go

@@ -0,0 +1,71 @@
+package test
+
+import (
+	"testing"
+
+	"github.com/miekg/dns"
+)
+
+func TestTemplateUpstream(t *testing.T) {
+	corefile := `.:0 {
+ 		# CNAME
+		template IN ANY cname.example.net. {
+			match ".*"
+			answer "cname.example.net. 60 IN CNAME target.example.net."
+			upstream
+		}
+
+		# Target
+		template IN A target.example.net. {
+			match ".*"
+			answer "target.example.net. 60 IN A 1.2.3.4"
+		}
+}
+`
+	i, udp, _, err := CoreDNSServerAndPorts(corefile)
+	if err != nil {
+		t.Fatalf("Could not get CoreDNS serving instance: %s", err)
+	}
+	defer i.Stop()
+
+	// Test that an A query returns a CNAME and an A record
+	m := new(dns.Msg)
+	m.SetQuestion("cname.example.net.", dns.TypeA)
+	m.SetEdns0(4096, true) // need this?
+
+	r, err := dns.Exchange(m, udp)
+	if err != nil {
+		t.Fatalf("Could not send msg: %s", err)
+	}
+	if r.Rcode == dns.RcodeServerFailure {
+		t.Fatalf("Rcode should not be dns.RcodeServerFailure")
+	}
+	if len(r.Answer) < 2 {
+		t.Fatalf("Expected 2 answers, got %v", len(r.Answer))
+	}
+	if x := r.Answer[0].(*dns.CNAME).Target; x != "target.example.net." {
+		t.Fatalf("Failed to get address for CNAME, expected target.example.net. got %s", x)
+	}
+	if x := r.Answer[1].(*dns.A).A.String(); x != "1.2.3.4" {
+		t.Fatalf("Failed to get address for CNAME, expected 1.2.3.4 got %s", x)
+	}
+
+	// Test that a CNAME query only returns a CNAME
+	m = new(dns.Msg)
+	m.SetQuestion("cname.example.net.", dns.TypeCNAME)
+	m.SetEdns0(4096, true) // need this?
+
+	r, err = dns.Exchange(m, udp)
+	if err != nil {
+		t.Fatalf("Could not send msg: %s", err)
+	}
+	if r.Rcode == dns.RcodeServerFailure {
+		t.Fatalf("Rcode should not be dns.RcodeServerFailure")
+	}
+	if len(r.Answer) < 1 {
+		t.Fatalf("Expected 1 answer, got %v", len(r.Answer))
+	}
+	if x := r.Answer[0].(*dns.CNAME).Target; x != "target.example.net." {
+		t.Fatalf("Failed to get address for CNAME, expected target.example.net. got %s", x)
+	}
+}