writer.js 7.4 KB

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  1. // Copyright 2011 Mark Cavage <mcavage@gmail.com> All rights reserved.
  2. var assert = require('assert');
  3. var ASN1 = require('./types');
  4. var errors = require('./errors');
  5. ///--- Globals
  6. var newInvalidAsn1Error = errors.newInvalidAsn1Error;
  7. var DEFAULT_OPTS = {
  8. size: 1024,
  9. growthFactor: 8
  10. };
  11. ///--- Helpers
  12. function merge(from, to) {
  13. assert.ok(from);
  14. assert.equal(typeof(from), 'object');
  15. assert.ok(to);
  16. assert.equal(typeof(to), 'object');
  17. var keys = Object.getOwnPropertyNames(from);
  18. keys.forEach(function(key) {
  19. if (to[key])
  20. return;
  21. var value = Object.getOwnPropertyDescriptor(from, key);
  22. Object.defineProperty(to, key, value);
  23. });
  24. return to;
  25. }
  26. ///--- API
  27. function Writer(options) {
  28. options = merge(DEFAULT_OPTS, options || {});
  29. this._buf = new Buffer(options.size || 1024);
  30. this._size = this._buf.length;
  31. this._offset = 0;
  32. this._options = options;
  33. // A list of offsets in the buffer where we need to insert
  34. // sequence tag/len pairs.
  35. this._seq = [];
  36. }
  37. Object.defineProperty(Writer.prototype, 'buffer', {
  38. get: function () {
  39. if (this._seq.length)
  40. throw new InvalidAsn1Error(this._seq.length + ' unended sequence(s)');
  41. return (this._buf.slice(0, this._offset));
  42. }
  43. });
  44. Writer.prototype.writeByte = function(b) {
  45. if (typeof(b) !== 'number')
  46. throw new TypeError('argument must be a Number');
  47. this._ensure(1);
  48. this._buf[this._offset++] = b;
  49. };
  50. Writer.prototype.writeInt = function(i, tag) {
  51. if (typeof(i) !== 'number')
  52. throw new TypeError('argument must be a Number');
  53. if (typeof(tag) !== 'number')
  54. tag = ASN1.Integer;
  55. var sz = 4;
  56. while ((((i & 0xff800000) === 0) || ((i & 0xff800000) === 0xff800000 >> 0)) &&
  57. (sz > 1)) {
  58. sz--;
  59. i <<= 8;
  60. }
  61. if (sz > 4)
  62. throw new InvalidAsn1Error('BER ints cannot be > 0xffffffff');
  63. this._ensure(2 + sz);
  64. this._buf[this._offset++] = tag;
  65. this._buf[this._offset++] = sz;
  66. while (sz-- > 0) {
  67. this._buf[this._offset++] = ((i & 0xff000000) >>> 24);
  68. i <<= 8;
  69. }
  70. };
  71. Writer.prototype.writeNull = function() {
  72. this.writeByte(ASN1.Null);
  73. this.writeByte(0x00);
  74. };
  75. Writer.prototype.writeEnumeration = function(i, tag) {
  76. if (typeof(i) !== 'number')
  77. throw new TypeError('argument must be a Number');
  78. if (typeof(tag) !== 'number')
  79. tag = ASN1.Enumeration;
  80. return this.writeInt(i, tag);
  81. };
  82. Writer.prototype.writeBoolean = function(b, tag) {
  83. if (typeof(b) !== 'boolean')
  84. throw new TypeError('argument must be a Boolean');
  85. if (typeof(tag) !== 'number')
  86. tag = ASN1.Boolean;
  87. this._ensure(3);
  88. this._buf[this._offset++] = tag;
  89. this._buf[this._offset++] = 0x01;
  90. this._buf[this._offset++] = b ? 0xff : 0x00;
  91. };
  92. Writer.prototype.writeString = function(s, tag) {
  93. if (typeof(s) !== 'string')
  94. throw new TypeError('argument must be a string (was: ' + typeof(s) + ')');
  95. if (typeof(tag) !== 'number')
  96. tag = ASN1.OctetString;
  97. var len = Buffer.byteLength(s);
  98. this.writeByte(tag);
  99. this.writeLength(len);
  100. if (len) {
  101. this._ensure(len);
  102. this._buf.write(s, this._offset);
  103. this._offset += len;
  104. }
  105. };
  106. Writer.prototype.writeBuffer = function(buf, tag) {
  107. if (typeof(tag) !== 'number')
  108. throw new TypeError('tag must be a number');
  109. if (!Buffer.isBuffer(buf))
  110. throw new TypeError('argument must be a buffer');
  111. this.writeByte(tag);
  112. this.writeLength(buf.length);
  113. this._ensure(buf.length);
  114. buf.copy(this._buf, this._offset, 0, buf.length);
  115. this._offset += buf.length;
  116. };
  117. Writer.prototype.writeStringArray = function(strings) {
  118. if ((!strings instanceof Array))
  119. throw new TypeError('argument must be an Array[String]');
  120. var self = this;
  121. strings.forEach(function(s) {
  122. self.writeString(s);
  123. });
  124. };
  125. // This is really to solve DER cases, but whatever for now
  126. Writer.prototype.writeOID = function(s, tag) {
  127. if (typeof(s) !== 'string')
  128. throw new TypeError('argument must be a string');
  129. if (typeof(tag) !== 'number')
  130. tag = ASN1.OID;
  131. if (!/^([0-9]+\.){3,}[0-9]+$/.test(s))
  132. throw new Error('argument is not a valid OID string');
  133. function encodeOctet(bytes, octet) {
  134. if (octet < 128) {
  135. bytes.push(octet);
  136. } else if (octet < 16384) {
  137. bytes.push((octet >>> 7) | 0x80);
  138. bytes.push(octet & 0x7F);
  139. } else if (octet < 2097152) {
  140. bytes.push((octet >>> 14) | 0x80);
  141. bytes.push(((octet >>> 7) | 0x80) & 0xFF);
  142. bytes.push(octet & 0x7F);
  143. } else if (octet < 268435456) {
  144. bytes.push((octet >>> 21) | 0x80);
  145. bytes.push(((octet >>> 14) | 0x80) & 0xFF);
  146. bytes.push(((octet >>> 7) | 0x80) & 0xFF);
  147. bytes.push(octet & 0x7F);
  148. } else {
  149. bytes.push(((octet >>> 28) | 0x80) & 0xFF);
  150. bytes.push(((octet >>> 21) | 0x80) & 0xFF);
  151. bytes.push(((octet >>> 14) | 0x80) & 0xFF);
  152. bytes.push(((octet >>> 7) | 0x80) & 0xFF);
  153. bytes.push(octet & 0x7F);
  154. }
  155. }
  156. var tmp = s.split('.');
  157. var bytes = [];
  158. bytes.push(parseInt(tmp[0], 10) * 40 + parseInt(tmp[1], 10));
  159. tmp.slice(2).forEach(function(b) {
  160. encodeOctet(bytes, parseInt(b, 10));
  161. });
  162. var self = this;
  163. this._ensure(2 + bytes.length);
  164. this.writeByte(tag);
  165. this.writeLength(bytes.length);
  166. bytes.forEach(function(b) {
  167. self.writeByte(b);
  168. });
  169. };
  170. Writer.prototype.writeLength = function(len) {
  171. if (typeof(len) !== 'number')
  172. throw new TypeError('argument must be a Number');
  173. this._ensure(4);
  174. if (len <= 0x7f) {
  175. this._buf[this._offset++] = len;
  176. } else if (len <= 0xff) {
  177. this._buf[this._offset++] = 0x81;
  178. this._buf[this._offset++] = len;
  179. } else if (len <= 0xffff) {
  180. this._buf[this._offset++] = 0x82;
  181. this._buf[this._offset++] = len >> 8;
  182. this._buf[this._offset++] = len;
  183. } else if (len <= 0xffffff) {
  184. this._buf[this._offset++] = 0x83;
  185. this._buf[this._offset++] = len >> 16;
  186. this._buf[this._offset++] = len >> 8;
  187. this._buf[this._offset++] = len;
  188. } else {
  189. throw new InvalidAsn1ERror('Length too long (> 4 bytes)');
  190. }
  191. };
  192. Writer.prototype.startSequence = function(tag) {
  193. if (typeof(tag) !== 'number')
  194. tag = ASN1.Sequence | ASN1.Constructor;
  195. this.writeByte(tag);
  196. this._seq.push(this._offset);
  197. this._ensure(3);
  198. this._offset += 3;
  199. };
  200. Writer.prototype.endSequence = function() {
  201. var seq = this._seq.pop();
  202. var start = seq + 3;
  203. var len = this._offset - start;
  204. if (len <= 0x7f) {
  205. this._shift(start, len, -2);
  206. this._buf[seq] = len;
  207. } else if (len <= 0xff) {
  208. this._shift(start, len, -1);
  209. this._buf[seq] = 0x81;
  210. this._buf[seq + 1] = len;
  211. } else if (len <= 0xffff) {
  212. this._buf[seq] = 0x82;
  213. this._buf[seq + 1] = len >> 8;
  214. this._buf[seq + 2] = len;
  215. } else if (len <= 0xffffff) {
  216. this._shift(start, len, 1);
  217. this._buf[seq] = 0x83;
  218. this._buf[seq + 1] = len >> 16;
  219. this._buf[seq + 2] = len >> 8;
  220. this._buf[seq + 3] = len;
  221. } else {
  222. throw new InvalidAsn1Error('Sequence too long');
  223. }
  224. };
  225. Writer.prototype._shift = function(start, len, shift) {
  226. assert.ok(start !== undefined);
  227. assert.ok(len !== undefined);
  228. assert.ok(shift);
  229. this._buf.copy(this._buf, start + shift, start, start + len);
  230. this._offset += shift;
  231. };
  232. Writer.prototype._ensure = function(len) {
  233. assert.ok(len);
  234. if (this._size - this._offset < len) {
  235. var sz = this._size * this._options.growthFactor;
  236. if (sz - this._offset < len)
  237. sz += len;
  238. var buf = new Buffer(sz);
  239. this._buf.copy(buf, 0, 0, this._offset);
  240. this._buf = buf;
  241. this._size = sz;
  242. }
  243. };
  244. ///--- Exported API
  245. module.exports = Writer;