add CAA packer, expand CCA parser

packer/type.caa.js

@@ -0,0 +1,69 @@
+(function (exports) {
+'use strict';
+
+// RFC 6844
+// Explanation: https://tools.ietf.org/html/rfc6844#section-3
+// Binary Format: https://tools.ietf.org/html/rfc6844#section-5
+// Real-world Usage: https://support.dnsimple.com/articles/caa-record/
+
+// 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_PACKER_TYPE_CAA = function (ab, dv, total, record) {
+  if ('number' !== typeof record.flag || isNaN(record.flag) || record.flag < 0 || record.flag > 255) {
+    console.log(record);
+    throw new Error("bad CAA flag:", record.flag);
+  }
+  if ('string' !== typeof record.tag || !record.tag || record.tag.length > 255) {
+    throw new Error("bad CAA tag:", record.tag);
+  }
+  if ('string' !== typeof record.value || !record.value) {
+    throw new Error("bad CAA value:", record.value);
+  }
+
+  // RDLEN = flag (1 byte) + taglen (1 byte) + tagstr (taglen bytes) + valuestr (valuelen bytes)
+  dv.setUint16(total, 1 + 1 + record.tag.length + record.value.length, false);
+  total += 2;
+
+  // FLAG
+  dv.setUint8(total, record.flag, false);
+  total += 1;
+
+  // TAG LENGTH
+  dv.setUint8(total, record.tag.length, false);
+  total += 1;
+
+  // TAG
+  record.tag.split('').forEach(function (ch) {
+    dv.setUint8(total, ch.charCodeAt(0), false);
+    total += 1;
+  });
+
+  // VALUE
+  record.value.split('').forEach(function (ch) {
+    dv.setUint8(total, ch.charCodeAt(0), false);
+    total += 1;
+  });
+
+  return total;
+};
+
+}('undefined' !== typeof window ? window : exports));

parser/type.caa.js

@@ -1,6 +1,9 @@
 (function (exports) {
 'use strict';
 
+// RFC 6844 https://tools.ietf.org/html/rfc6844#section-3
+// https://support.dnsimple.com/articles/caa-record/
+
 // A Certification Authority Authorization (CAA) record is used to specify which
 // certificate authorities (CAs) are allowed to issue certificates for a domain.
 
@@ -26,13 +29,23 @@ 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++];
+  var flag = data[i];
+  var mid = data[i + 1];
+  i += 2;
   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++]); }
+  var tag = '';
+  var value = '';
+
+  while (i < mid) {
+    tag += String.fromCharCode(data[i]);
+    i += 1;
+  }
+
+  while (i < end) {
+    value += String.fromCharCode(data[i]);
+    i += 1;
+  }
 
   record.flag = flag;
   record.tag = tag;