Add parser for CAA record

parser/type.caa.js

@@ -0,0 +1,44 @@
+(function (exports) {
+'use strict';
+
+// A Certification Authority Authorization (CAA) record is used to specify which
+// certificate authorities (CAs) are allowed to issue certificates for a domain.
+
+// Value    Meaning/Use
+//
+// Flag     An unsigned integer between 0-255.
+//          It is currently used to represent the critical flag, that has a
+//          specific meaning per RFC 6844
+// Tag      An ASCII string that represents the identifier of the property
+//          represented by the record.
+// Value    The value associated with the tag.
+
+// The RFC currently defines 3 available tags:
+//
+// - issue:     explicity authorizes a single certificate authority to issue a
+//              certificate (any type) for the hostname.
+// - issuewild: explicity authorizes a single certificate authority to issue a
+//              wildcard certificate (and only wildcard) for the hostname.
+// - iodef:     specifies an URL to which a certificate authority may report
+//              policy violations.
+
+exports.DNS_PARSER_TYPE_CAA = function (ab, packet, record) {
+
+  var data = new Uint8Array(ab);
+  var i = record.rdstart;
+  var flag = data[i++];
+  var mid = data[i++];
+  mid += i;
+  var end = record.rdstart + record.rdlength;
+  var tag = '', value = '';
+  while (i < mid) { tag += String.fromCharCode(data[i++]); }
+  while (i < end) { value += String.fromCharCode(data[i++]); }
+
+  record.flag = flag;
+  record.tag = tag;
+  record.value = value;
+
+  return record;
+};
+
+}('undefined' !== typeof window ? window : exports));