- compliance with metadata contract. If metadata value is empty, ignore rewrite - like if metadata does not exist. (#1953)

plugin/rewrite/edns0.go

@@ -203,7 +203,10 @@ func (rule *edns0VariableRule) ruleData(ctx context.Context, state request.Reque
 
 	fetcher := metadata.ValueFunc(ctx, rule.variable[1:len(rule.variable)-1])
 	if fetcher != nil {
-		return []byte(fetcher()), nil
+		value := fetcher()
+		if len(value) > 0 {
+			return []byte(value), nil
+		}
 	}
 
 	return nil, fmt.Errorf("unable to extract data for variable %s", rule.variable)

plugin/rewrite/rewrite_test.go

@@ -523,8 +523,8 @@ func TestRewriteEDNS0LocalVariable(t *testing.T) {
 		{
 			[]dns.EDNS0{},
 			[]string{"local", "set", "0xffee", "{test/empty}"},
-			[]dns.EDNS0{&dns.EDNS0_LOCAL{Code: 0xffee, Data: []byte("")}},
-			true,
+			nil,
+			false,
 		},
 		{
 			[]dns.EDNS0{},