Support for writing OIDs (DER)

Author: Mark Cavage

lib/ber/writer.js

@@ -101,6 +101,12 @@ Writer.prototype.writeInt = function(i, tag) {
 };
 
 
+Writer.prototype.writeNull = function() {
+  this.writeByte(ASN1.Null);
+  this.writeByte(0x00);
+};
+
+
 Writer.prototype.writeEnumeration = function(i, tag) {
   if (typeof(i) !== 'number')
     throw new TypeError('argument must be a Number');
@@ -151,6 +157,50 @@ Writer.prototype.writeStringArray = function(strings) {
   });
 };
 
+// This is really to solve DER cases, but whatever for now
+Writer.prototype.writeOID = function(s, tag) {
+  if (typeof(s) !== 'string')
+    throw new TypeError('argument must be a string');
+  if (typeof(tag) !== 'number')
+    tag = ASN1.OID;
+
+  if (!/^([0-9]+\.){3,}[0-9]+$/.test(s))
+    throw new Error('argument is not a valid OID string');
+
+  function encodeOctet(bytes, octet) {
+    if (octet < 128) {
+        bytes.push(octet);
+    } else if (octet < 16384) {
+        bytes.push((octet >>> 7) | 0x80);
+        bytes.push(octet & 0x7F);
+    } else if (octet < 2097152) {
+      bytes.push((octet >>> 14) | 0x80);
+      bytes.push(((octet >>> 7) | 0x80) & 0xFF);
+      bytes.push(octet & 0x7F);
+    } else if (id < 268435456) {
+      bytes.push((octet >>> 21) | 0x80);
+      bytes.push(((octet >>> 14) | 0x80) & 0xFF);
+      bytes.push(((octet >>> 7) | 0x80) & 0xFF);
+      bytes.push(octet & 0x7F);
+    }
+  }
+
+  var tmp = s.split('.');
+  var bytes = [];
+  bytes.push(parseInt(tmp[0], 10) * 40 + parseInt(tmp[1], 10));
+  tmp.slice(2).forEach(function(b) {
+    encodeOctet(bytes, parseInt(b, 10));
+  });
+
+  var self = this;
+  this._ensure(2 + bytes.length);
+  this.writeByte(tag);
+  this.writeLength(bytes.length);
+  bytes.forEach(function(b) {
+    self.writeByte(b);
+  });
+};
+
 
 Writer.prototype.writeLength = function(len) {
   if (typeof(len) !== 'number')
@@ -212,7 +262,7 @@ Writer.prototype.endSequence = function() {
     this._buf[seq + 2] = len >> 8;
     this._buf[seq + 3] = len;
   } else {
-    throw newInvalidAsn1ERror('Sequence too long');
+    throw newInvalidAsn1Error('Sequence too long');
   }
 };
 

package.json

@@ -2,7 +2,7 @@
   "author": "Mark Cavage <mcavage@gmail.com>",
   "name": "asn1",
   "description": "Contains parsers and serializers for ASN.1 (currently BER only)",
-  "version": "0.1.6",
+  "version": "0.1.7",
   "repository": {
     "type": "git",
     "url": "git://github.com/mcavage/node-asn1.git"

tst/ber/writer.test.js

@@ -257,3 +257,18 @@ test('LDAP bind message', function(t) {
   t.end();
 });
 
+
+test('Write OID', function(t) {
+  var oid = '1.2.840.113549.1.1.1';
+  var writer = new BerWriter();
+  writer.writeOID(oid);
+
+  var ber = writer.buffer;
+  t.ok(ber);
+  console.log(require('util').inspect(ber));
+  console.log(require('util').inspect(new Buffer([0x06, 0x09, 0x2a, 0x86,
+                                                  0x48, 0x86, 0xf7, 0x0d,
+                                                  0x01, 0x01, 0x01])));
+
+  t.end();
+});