// ASN.1 JavaScript decoder
// Copyright (c) 2008-2009 Lapo Luchini <lapo@lapo.it>
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice appear in all copies.
//
// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
// ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
// ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
// OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
function Stream(enc, pos) {
if (enc instanceof Stream) {
this.enc = enc.enc;
this.pos = enc.pos;
} else {
this.enc = enc;
this.pos = pos;
}
}
Stream.prototype.get = function(pos) {
if (pos == undefined)
pos = this.pos++;
if (pos >= this.enc.length)
throw 'Requesting byte offset ' + pos + ' on a stream of length ' + this.enc.length;
return this.enc[pos];
}
Stream.prototype.hexDigits = "0123456789ABCDEF";
Stream.prototype.hexDump = function(start, end) {
var s = "";
for (var i = start; i < end; ++i) {
var h = this.get(i);
s += this.hexDigits.charAt(h >> 4) + this.hexDigits.charAt(h & 0xF);
if ((i & 0xF) == 0x7)
s += ' ';
s += ((i & 0xF) == 0xF) ? '\n' : ' ';
}
return s;
}
Stream.prototype.parseStringISO = function(start, end) {
var s = "";
for (var i = start; i < end; ++i)
s += String.fromCharCode(this.get(i));
return s;
}
Stream.prototype.parseStringUTF = function(start, end) {
var s = "", c = 0;
for (var i = start; i < end; ) {
var c = this.get(i++);
if (c < 128)
s += String.fromCharCode(c);
else if ((c > 191) && (c < 224))
s += String.fromCharCode(((c & 0x1F) << 6) | (this.get(i++) & 0x3F));
else
s += String.fromCharCode(((c & 0x0F) << 12) | ((this.get(i++) & 0x3F) << 6) | (this.get(i++) & 0x3F));
//TODO: this doesn't check properly 'end', some char could begin before and end after
}
return s;
}
Stream.prototype.reTime = /^((?:1[89]|2\d)?\d\d)(0[1-9]|1[0-2])(0[1-9]|[12]\d|3[01])([01]\d|2[0-3])(?:([0-5]\d)(?:([0-5]\d)(?:[.,](\d{1,3}))?)?)?(Z|[-+](?:[0]\d|1[0-2])([0-5]\d)?)?$/;
Stream.prototype.parseTime = function(start, end) {
var s = this.parseStringISO(start, end);
var m = this.reTime.exec(s);
if (!m)
return "Unrecognized time: " + s;
s = m[1] + "-" + m[2] + "-" + m[3] + " " + m[4];
if (m[5]) {
s += ":" + m[5];
if (m[6]) {
s += ":" + m[6];
if (m[7])
s += "." + m[7];
}
}
if (m[8]) {
s += " UTC";
if (m[8] != 'Z') {
s += m[8];
if (m[9])
s += ":" + m[9];
}
}
return s;
}
Stream.prototype.parseInteger = function(start, end) {
if ((end - start) > 4)
return undefined;
//TODO support negative numbers
var n = 0;
for (var i = start; i < end; ++i)
n = (n << 8) | this.get(i);
return n;
}
Stream.prototype.parseOID = function(start, end) {
var s, n = 0, bits = 0;
for (var i = start; i < end; ++i) {
var v = this.get(i);
n = (n << 7) | (v & 0x7F);
bits += 7;
if (!(v & 0x80)) { // finished
if (s == undefined)
s = parseInt(n / 40) + "." + (n % 40);
else
s += "." + ((bits >= 31) ? "big" : n);
n = bits = 0;
}
s += String.fromCharCode();
}
return s;
}
function ASN1(stream, header, length, tag, sub) {
this.stream = stream;
this.header = header;
this.length = length;
this.tag = tag;
this.sub = sub;
}
ASN1.prototype.typeName = function() {
if (this.tag == undefined)
return "unknown";
var tagClass = this.tag >> 6;
var tagConstructed = (this.tag >> 5) & 1;
var tagNumber = this.tag & 0x1F;
switch (tagClass) {
case 0: // universal
switch (tagNumber) {
case 0x00: return "EOC";
case 0x01: return "BOOLEAN";
case 0x02: return "INTEGER";
case 0x03: return "BIT_STRING";
case 0x04: return "OCTET_STRING";
case 0x05: return "NULL";
case 0x06: return "OBJECT_IDENTIFIER";
case 0x07: return "ObjectDescriptor";
case 0x08: return "EXTERNAL";
case 0x09: return "REAL";
case 0x0A: return "ENUMERATED";
case 0x0B: return "EMBEDDED_PDV";
case 0x0C: return "UTF8String";
case 0x10: return "SEQUENCE";
case 0x11: return "SET";
case 0x12: return "NumericString";
case 0x13: return "PrintableString"; // ASCII subset
case 0x14: return "TeletexString"; // aka T61String
case 0x15: return "VideotexString";
case 0x16: return "IA5String"; // ASCII
case 0x17: return "UTCTime";
case 0x18: return "GeneralizedTime";
case 0x19: return "GraphicString";
case 0x1A: return "VisibleString"; // ASCII subset
case 0x1B: return "GeneralString";
case 0x1C: return "UniversalString";
case 0x1E: return "BMPString";
default: return "Universal_" + tagNumber.toString(16);
}
case 1: return "Application_" + tagNumber.toString(16);
case 2: return "[" + tagNumber + "]"; // Context
case 3: return "Private_" + tagNumber.toString(16);
}
}
ASN1.prototype.content = function() {
if (this.tag == undefined)
return null;
var tagClass = this.tag >> 6;
if (tagClass != 0) // universal
return null;
var tagNumber = this.tag & 0x1F;
var content = this.posContent();
var len = Math.abs(this.length);
switch (tagNumber) {
case 0x01: // BOOLEAN
return (this.stream.get(content) == 0) ? "false" : "true";
case 0x02: // INTEGER
return this.stream.parseInteger(content, content + len);
//case 0x03: // BIT_STRING
//case 0x04: // OCTET_STRING
//case 0x05: // NULL
case 0x06: // OBJECT_IDENTIFIER
return this.stream.parseOID(content, content + len);
//case 0x07: // ObjectDescriptor
//case 0x08: // EXTERNAL
//case 0x09: // REAL
//case 0x0A: // ENUMERATED
//case 0x0B: // EMBEDDED_PDV
//case 0x10: // SEQUENCE
//case 0x11: // SET
case 0x0C: // UTF8String
return this.stream.parseStringUTF(content, content + len);
case 0x12: // NumericString
case 0x13: // PrintableString
case 0x14: // TeletexString
case 0x15: // VideotexString
case 0x16: // IA5String
//case 0x19: // GraphicString
case 0x1A: // VisibleString
//case 0x1B: // GeneralString
//case 0x1C: // UniversalString
//case 0x1E: // BMPString
return this.stream.parseStringISO(content, content + len);
case 0x17: // UTCTime
case 0x18: // GeneralizedTime
return this.stream.parseTime(content, content + len);
}
return null;
}
ASN1.prototype.toString = function() {
return this.typeName() + "@" + this.stream.pos + "[header:" + this.header + ",length:" + this.length + ",sub:" + ((this.sub == null) ? 'null' : this.sub.length) + "]";
}
ASN1.prototype.print = function(indent) {
if (indent == undefined) indent = '';
document.writeln(indent + this);
if (this.sub != null) {
indent += ' ';
for (var i = 0, max = this.sub.length; i < max; ++i)
this.sub[i].print(indent);
}
}
ASN1.prototype.toPrettyString = function(indent) {
if (indent == undefined) indent = '';
var s = indent + this.typeName() + " @" + this.stream.pos;
if (this.length >= 0)
s += "+";
s += this.length;
if (this.tag & 0x20)
s += " (constructed)";
else if (((this.tag == 0x03) || (this.tag == 0x04)) && (this.sub != null))
s += " (encapsulates)";
s += "\n";
if (this.sub != null) {
indent += ' ';
for (var i = 0, max = this.sub.length; i < max; ++i)
s += this.sub[i].toPrettyString(indent);
}
return s;
}
ASN1.prototype.toDOM = function() {
var node = document.createElement("div");
node.className = "node";
node.asn1 = this;
var head = document.createElement("div");
head.className = "head";
var s = this.typeName();
head.innerHTML = s;
node.appendChild(head);
this.head = head;
var value = document.createElement("div");
value.className = "value";
s = "Offset: " + this.stream.pos + "<br/>";
s += "Length: " + this.header + "+";
if (this.length >= 0)
s += this.length;
else
s += (-this.length) + " (undefined)";
if (this.tag & 0x20)
s += "<br/>(constructed)";
else if (((this.tag == 0x03) || (this.tag == 0x04)) && (this.sub != null))
s += "<br/>(encapsulates)";
var content = this.content();
if (content != null) {
s += "<br/>Value:<br/><b>" + content + "</b>";
if ((typeof(oids) == 'object') && (this.tag == 0x06)) {
var oid = oids[content];
if (oid) {
if (oid.d) s += "<br/>" + oid.d;
if (oid.c) s += "<br/>" + oid.c;
if (oid.w) s += "<br/>(warning!)";
}
}
}
value.innerHTML = s;
node.appendChild(value);
var sub = document.createElement("div");
sub.className = "sub";
if (this.sub != null) {
for (var i = 0, max = this.sub.length; i < max; ++i)
sub.appendChild(this.sub[i].toDOM());
}
node.appendChild(sub);
head.switchNode = node;
head.onclick = function() {
var node = this.switchNode;
node.className = (node.className == "node collapsed") ? "node" : "node collapsed";
};
return node;
}
ASN1.prototype.posStart = function() {
return this.stream.pos;
}
ASN1.prototype.posContent = function() {
return this.stream.pos + this.header;
}
ASN1.prototype.posEnd = function() {
return this.stream.pos + this.header + Math.abs(this.length);
}
ASN1.prototype.toHexDOM_sub = function(node, className, stream, start, end) {
if (start >= end)
return;
var sub = document.createElement("span");
sub.className = className;
sub.appendChild(document.createTextNode(
stream.hexDump(start, end)));
node.appendChild(sub);
}
ASN1.prototype.toHexDOM = function() {
var node = document.createElement("span");
node.className = 'hex';
this.head.hexNode = node;
this.head.onmouseover = function() { this.hexNode.className = 'hexCurrent'; }
this.head.onmouseout = function() { this.hexNode.className = 'hex'; }
this.toHexDOM_sub(node, "tag", this.stream, this.posStart(), this.posStart() + 1);
this.toHexDOM_sub(node, (this.length >= 0) ? "dlen" : "ulen", this.stream, this.posStart() + 1, this.posContent());
if (this.sub == null)
node.appendChild(document.createTextNode(
this.stream.hexDump(this.posContent(), this.posEnd())));
else if (this.sub.length > 0) {
var first = this.sub[0];
var last = this.sub[this.sub.length - 1];
this.toHexDOM_sub(node, "intro", this.stream, this.posContent(), first.posStart());
for (var i = 0, max = this.sub.length; i < max; ++i)
node.appendChild(this.sub[i].toHexDOM());
this.toHexDOM_sub(node, "outro", this.stream, last.posEnd(), this.posEnd());
}
return node;
}
/*
ASN1.prototype.getValue = function() {
TODO
}
*/
ASN1.decodeLength = function(stream) {
var buf = stream.get();
var len = buf & 0x7F;
if (len == buf)
return len;
if (len > 3)
throw "Length over 24 bits not supported at position " + (stream.pos - 1);
if (len == 0)
return -1; // undefined
buf = 0;
for (var i = 0; i < len; ++i)
buf = (buf << 8) | stream.get();
return buf;
}
ASN1.hasContent = function(tag, len, stream) {
if (tag & 0x20) // constructed
return true;
if ((tag < 0x03) || (tag > 0x04))
return false;
var p = new Stream(stream);
if (tag == 0x03) p.get(); // BitString unused bits, must be in [0, 7]
var subTag = p.get();
if ((subTag >> 6) & 0x01) // not (universal or context)
return false;
try {
var subLength = ASN1.decodeLength(p);
return ((p.pos - stream.pos) + subLength == len);
} catch (exception) {
return false;
}
}
ASN1.decode = function(stream) {
if (!(stream instanceof Stream))
stream = new Stream(stream, 0);
var streamStart = new Stream(stream);
var tag = stream.get();
var len = ASN1.decodeLength(stream);
var header = stream.pos - streamStart.pos;
var sub = null;
if (ASN1.hasContent(tag, len, stream)) {
// it has content, so we decode it
var start = stream.pos;
if (tag == 0x03) stream.get(); // skip BitString unused bits, must be in [0, 7]
sub = [];
if (len >= 0) {
// definite length
var end = start + len;
while (stream.pos < end)
sub[sub.length] = ASN1.decode(stream);
if (stream.pos != end)
throw "Content size is not correct for container starting at offset " + start;
} else {
// undefined length
try {
for (;;) {
var s = ASN1.decode(stream);
if (s.tag == 0)
break;
sub[sub.length] = s;
}
len = start - stream.pos;
} catch (e) {
throw "Exception while decoding undefined length content: " + e;
}
}
} else
stream.pos += len; // skip content
return new ASN1(streamStart, header, len, tag, sub);
}
ASN1.test = function() {
var test = [
{ value: [0x27], expected: 0x27 },
{ value: [0x81, 0xC9], expected: 0xC9 },
{ value: [0x83, 0xFE, 0xDC, 0xBA], expected: 0xFEDCBA },
];
for (var i = 0, max = test.length; i < max; ++i) {
var pos = 0;
var stream = new Stream(test[i].value, 0);
var res = ASN1.decodeLength(stream);
if (res != test[i].expected)
document.write("In test[" + i + "] expected " + test[i].expected + " got " + res + "\n");
}
}
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