--- /dev/null
+// Copyright 2011 Mark Cavage <mcavage@gmail.com> All rights reserved.
+
+var assert = require('assert');
+
+var ASN1 = require('./types');
+var errors = require('./errors');
+
+
+///--- Globals
+
+var newInvalidAsn1Error = errors.newInvalidAsn1Error;
+
+
+
+///--- API
+
+function Reader(data) {
+ if (!data || !Buffer.isBuffer(data))
+ throw new TypeError('data must be a node Buffer');
+
+ this._buf = data;
+ this._size = data.length;
+
+ // These hold the "current" state
+ this._len = 0;
+ this._offset = 0;
+}
+
+Object.defineProperty(Reader.prototype, 'length', {
+ enumerable: true,
+ get: function () { return (this._len); }
+});
+
+Object.defineProperty(Reader.prototype, 'offset', {
+ enumerable: true,
+ get: function () { return (this._offset); }
+});
+
+Object.defineProperty(Reader.prototype, 'remain', {
+ get: function () { return (this._size - this._offset); }
+});
+
+Object.defineProperty(Reader.prototype, 'buffer', {
+ get: function () { return (this._buf.slice(this._offset)); }
+});
+
+
+/**
+ * Reads a single byte and advances offset; you can pass in `true` to make this
+ * a "peek" operation (i.e., get the byte, but don't advance the offset).
+ *
+ * @param {Boolean} peek true means don't move offset.
+ * @return {Number} the next byte, null if not enough data.
+ */
+Reader.prototype.readByte = function(peek) {
+ if (this._size - this._offset < 1)
+ return null;
+
+ var b = this._buf[this._offset] & 0xff;
+
+ if (!peek)
+ this._offset += 1;
+
+ return b;
+};
+
+
+Reader.prototype.peek = function() {
+ return this.readByte(true);
+};
+
+
+/**
+ * Reads a (potentially) variable length off the BER buffer. This call is
+ * not really meant to be called directly, as callers have to manipulate
+ * the internal buffer afterwards.
+ *
+ * As a result of this call, you can call `Reader.length`, until the
+ * next thing called that does a readLength.
+ *
+ * @return {Number} the amount of offset to advance the buffer.
+ * @throws {InvalidAsn1Error} on bad ASN.1
+ */
+Reader.prototype.readLength = function(offset) {
+ if (offset === undefined)
+ offset = this._offset;
+
+ if (offset >= this._size)
+ return null;
+
+ var lenB = this._buf[offset++] & 0xff;
+ if (lenB === null)
+ return null;
+
+ if ((lenB & 0x80) == 0x80) {
+ lenB &= 0x7f;
+
+ if (lenB == 0)
+ throw newInvalidAsn1Error('Indefinite length not supported');
+
+ if (lenB > 4)
+ throw newInvalidAsn1Error('encoding too long');
+
+ if (this._size - offset < lenB)
+ return null;
+
+ this._len = 0;
+ for (var i = 0; i < lenB; i++)
+ this._len = (this._len << 8) + (this._buf[offset++] & 0xff);
+
+ } else {
+ // Wasn't a variable length
+ this._len = lenB;
+ }
+
+ return offset;
+};
+
+
+/**
+ * Parses the next sequence in this BER buffer.
+ *
+ * To get the length of the sequence, call `Reader.length`.
+ *
+ * @return {Number} the sequence's tag.
+ */
+Reader.prototype.readSequence = function(tag) {
+ var seq = this.peek();
+ if (seq === null)
+ return null;
+ if (tag !== undefined && tag !== seq)
+ throw newInvalidAsn1Error('Expected 0x' + tag.toString(16) +
+ ': got 0x' + seq.toString(16));
+
+ var o = this.readLength(this._offset + 1); // stored in `length`
+ if (o === null)
+ return null;
+
+ this._offset = o;
+ return seq;
+};
+
+
+Reader.prototype.readInt = function() {
+ return this._readTag(ASN1.Integer);
+};
+
+
+Reader.prototype.readBoolean = function() {
+ return (this._readTag(ASN1.Boolean) === 0 ? false : true);
+};
+
+
+Reader.prototype.readEnumeration = function() {
+ return this._readTag(ASN1.Enumeration);
+};
+
+
+Reader.prototype.readString = function(tag, retbuf) {
+ if (!tag)
+ tag = ASN1.OctetString;
+
+ var b = this.peek();
+ if (b === null)
+ return null;
+
+ if (b !== tag)
+ throw newInvalidAsn1Error('Expected 0x' + tag.toString(16) +
+ ': got 0x' + b.toString(16));
+
+ var o = this.readLength(this._offset + 1); // stored in `length`
+
+ if (o === null)
+ return null;
+
+ if (this.length > this._size - o)
+ return null;
+
+ this._offset = o;
+
+ if (this.length === 0)
+ return retbuf ? new Buffer(0) : '';
+
+ var str = this._buf.slice(this._offset, this._offset + this.length);
+ this._offset += this.length;
+
+ return retbuf ? str : str.toString('utf8');
+};
+
+Reader.prototype.readOID = function(tag) {
+ if (!tag)
+ tag = ASN1.OID;
+
+ var b = this.readString(tag, true);
+ if (b === null)
+ return null;
+
+ var values = [];
+ var value = 0;
+
+ for (var i = 0; i < b.length; i++) {
+ var byte = b[i] & 0xff;
+
+ value <<= 7;
+ value += byte & 0x7f;
+ if ((byte & 0x80) == 0) {
+ values.push(value);
+ value = 0;
+ }
+ }
+
+ value = values.shift();
+ values.unshift(value % 40);
+ values.unshift((value / 40) >> 0);
+
+ return values.join('.');
+};
+
+
+Reader.prototype._readTag = function(tag) {
+ assert.ok(tag !== undefined);
+
+ var b = this.peek();
+
+ if (b === null)
+ return null;
+
+ if (b !== tag)
+ throw newInvalidAsn1Error('Expected 0x' + tag.toString(16) +
+ ': got 0x' + b.toString(16));
+
+ var o = this.readLength(this._offset + 1); // stored in `length`
+ if (o === null)
+ return null;
+
+ if (this.length > 4)
+ throw newInvalidAsn1Error('Integer too long: ' + this.length);
+
+ if (this.length > this._size - o)
+ return null;
+ this._offset = o;
+
+ var fb = this._buf[this._offset];
+ var value = 0;
+
+ for (var i = 0; i < this.length; i++) {
+ value <<= 8;
+ value |= (this._buf[this._offset++] & 0xff);
+ }
+
+ if ((fb & 0x80) == 0x80 && i !== 4)
+ value -= (1 << (i * 8));
+
+ return value >> 0;
+};
+
+
+
+///--- Exported API
+
+module.exports = Reader;
Code Review / simantics / district.git / blobdiff