v1.1.0: add case for known primitive-only values

README.md

@@ -71,14 +71,22 @@ Note: `value` will be a `Uint8Array`, not a hex string.
 
 ### Optimistic Parsing
 
-This is a dumbed-down, minimal ASN1 parser.
+This is a dumbed-down, minimal ASN1 parser
+(though quite clever in its simplicity).
 
-Rather than incorporating knowledge of each possible x509 schema
-to know whether to traverse deeper into a value container,
-it always tries to dive in (and backs out when parsing fails).
+There are some ASN.1 types (at least Bit String and Octet String,
+possibly others) that can be treated either as primitive values or
+as container types base on the schema being used.
 
-It is possible that it will produce false positives, but not likely
-in real-world scenarios (PEM, x509, CSR, etc).
+Rather than incorporating knowledge of each possible x509 schema,
+this parser will return values for types that are _always_ values,
+it recurse on types that are _always_ containers and, for ambigiuous
+types, it will first try to recurse and, on error, will fall back to
+returning a value.
+
+In theory, it is possible that it will produce false positives,
+but that would be highly unlikely in real-world scenarios
+(PEM, x509, PKCS#1, SEC1, PKCS#8, SPKI, PKIX, CSR, etc).
 
 I'd be interested to hear if you encounter such a case.
 

asn1-parser.js

@@ -15,10 +15,12 @@ var PEM = exports.PEM;
 
 ASN1.ELOOP = "uASN1.js Error: iterated over 15+ elements (probably a malformed file)";
 ASN1.EDEEP = "uASN1.js Error: element nested 20+ layers deep (probably a malformed file)";
-// Container Types are Sequence 0x30, Octect String 0x04, Array? (0xA0, 0xA1)
-// Value Types are Integer 0x02, Bit String 0x03, Null 0x05, Object ID 0x06,
+// Container Types are Sequence 0x30, Container Array? (0xA0, 0xA1)
+// Value Types are Integer 0x02, Null 0x05, Object ID 0x06, Value Array? (0x82)
+// Bit String (0x03) and Octet String (0x04) may be values or containers
 // Sometimes Bit String is used as a container (RSA Pub Spki)
 ASN1.CTYPES = [ 0x30, 0x31, 0xa0, 0xa1 ];
+ASN1.VTYPES = [ 0x02, 0x05, 0x06, 0x82 ];
 ASN1.parse = function parseAsn1(buf, depth, ws) {
   if (!ws) { ws = ''; }
   if (!depth) { depth = 0; }
@@ -81,23 +83,21 @@ ASN1.parse = function parseAsn1(buf, depth, ws) {
     return asn1;
   }
 
-  // We want to fail if we know for sure that it's bad
-  if (-1 !== ASN1.CTYPES.indexOf(asn1.type)) {
-    return parseChildren();
-  }
+  // Recurse into types that are _always_ containers
+  if (-1 !== ASN1.CTYPES.indexOf(asn1.type)) { return parseChildren(); }
 
+  // Return types that are _always_ values
   asn1.value = buf.slice(index, index + adjustedLen);
-  try {
-    return parseChildren(true);
-  } catch(e) {
-    // leaving iterable array as a matter of convenience
-    asn1.children = [];
-    return asn1;
-  }
+  if (-1 !== ASN1.VTYPES.indexOf(asn1.type)) { return asn1; }
+
+  // For ambigious / unknown types, recurse and return on failure
+  // (and return child array size to zero)
+  try { return parseChildren(true); }
+  catch(e) { asn1.children.length = 0; return asn1; }
 };
 ASN1._replacer = function (k, v) {
   if ('type' === k) { return '0x' + Enc.numToHex(v); }
-  if ('value' === k) { return '0x' + Enc.bufToHex(v.data || v); }
+  if (v && 'value' === k) { return '0x' + Enc.bufToHex(v.data || v); }
   return v;
 };
 

index.html

@@ -26,10 +26,9 @@ rMjgyCokrnjDft6Y/YnA4A50yZe7CnFsqeDcpnPbubP6cpYiVcnevNIYyg==
     var $input = document.querySelector('.js-input');
 
     function convert() {
-      console.log('change');
+      console.log('keyup');
       var pem = PEM.parseBlock(document.querySelector('.js-input').value);
       var hex = Enc.bufToHex(pem.der);
-      console.log(hex);
       document.querySelector('.js-hex').innerText = hex
         .match(/.{2}/g).join(' ').match(/.{1,24}/g).join(' ').match(/.{1,50}/g).join('\n');
       var json = ASN1.parse(pem.der);

package.json

@@ -1,6 +1,6 @@
 {
   "name": "asn1-parser",
-  "version": "1.0.2",
+  "version": "1.1.0",
   "description": "An ASN.1 parser in less than 100 lines of Vanilla JavaScript, part of the Bluecrypt suite.",
   "homepage": "https://git.coolaj86.com/coolaj86/asn1-parser.js",
   "main": "asn1-parser.js",