225 lines
9.7 KiB
HTML
225 lines
9.7 KiB
HTML
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<h1 class="page-title">Source: packet/compressed.js</h1>
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<article>
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<pre class="prettyprint source"><code>// GPG4Browsers - An OpenPGP implementation in javascript
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// Copyright (C) 2011 Recurity Labs GmbH
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//
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// This library is free software; you can redistribute it and/or
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// modify it under the terms of the GNU Lesser General Public
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// License as published by the Free Software Foundation; either
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// version 2.1 of the License, or (at your option) any later version.
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//
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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// Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public
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// License along with this library; if not, write to the Free Software
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// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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/**
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* Implementation of the Compressed Data Packet (Tag 8)<br/>
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* <br/>
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* RFC4880 5.6: The Compressed Data packet contains compressed data. Typically,
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* this packet is found as the contents of an encrypted packet, or following
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* a Signature or One-Pass Signature packet, and contains a literal data packet.
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* @requires compression/jxg
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* @requires encoding/base64
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* @requires enums
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* @module packet/compressed
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*/
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var enums = require('../enums.js'),
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JXG = require('../compression/jxg.js'),
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base64 = require('../encoding/base64.js');
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/**
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* @constructor
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*/
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module.exports = function compressed() {
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/**
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* List of packets
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* @type {module:packet/packetlist}
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*/
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this.packets = null;
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/**
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* Compression algorithm
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* @type {compression}
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*/
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this.algorithm = 'uncompressed';
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/**
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* Compressed packet data
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* @type {String}
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*/
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this.compressed = null;
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/**
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* Parsing function for the packet.
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* @param {String} bytes Payload of a tag 8 packet
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*/
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this.read = function(bytes) {
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// One octet that gives the algorithm used to compress the packet.
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this.algorithm = enums.read(enums.compression, bytes.charCodeAt(0));
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// Compressed data, which makes up the remainder of the packet.
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this.compressed = bytes.substr(1);
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this.decompress();
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}
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/**
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* Return the compressed packet.
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* @return {String} binary compressed packet
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*/
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this.write = function() {
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if (this.compressed == null)
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this.compress();
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return String.fromCharCode(enums.write(enums.compression, this.algorithm)) + this.compressed;
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}
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/**
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* Decompression method for decompressing the compressed data
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* read by read_packet
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*/
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this.decompress = function() {
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var decompressed;
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switch (this.algorithm) {
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case 'uncompressed':
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decompressed = this.compressed;
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break;
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case 'zip':
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var compData = this.compressed;
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var radix = base64.encode(compData).replace(/\n/g, "");
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// no header in this case, directly call deflate
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var jxg_obj = new JXG.Util.Unzip(JXG.Util.Base64.decodeAsArray(radix));
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decompressed = unescape(jxg_obj.deflate()[0][0]);
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break;
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case 'zlib':
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//RFC 1950. Bits 0-3 Compression Method
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var compressionMethod = this.compressed.charCodeAt(0) % 0x10;
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//Bits 4-7 RFC 1950 are LZ77 Window. Generally this value is 7 == 32k window size.
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// 2nd Byte in RFC 1950 is for "FLAGs" Allows for a Dictionary
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// (how is this defined). Basic checksum, and compression level.
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if (compressionMethod == 8) { //CM 8 is for DEFLATE, RFC 1951
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// remove 4 bytes ADLER32 checksum from the end
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var compData = this.compressed.substring(0, this.compressed.length - 4);
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var radix = base64.encode(compData).replace(/\n/g, "");
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//TODO check ADLER32 checksum
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decompressed = JXG.decompress(radix);
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break;
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} else {
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throw new Error("Compression algorithm ZLIB only supports " +
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"DEFLATE compression method.");
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}
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break;
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case 'bzip2':
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// TODO: need to implement this
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throw new Error('Compression algorithm BZip2 [BZ2] is not implemented.');
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break;
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default:
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throw new Error("Compression algorithm unknown :" + this.alogrithm);
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break;
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}
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this.packets.read(decompressed);
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}
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/**
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* Compress the packet data (member decompressedData)
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*/
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this.compress = function() {
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switch (this.algorithm) {
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case 'uncompressed':
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// - Uncompressed
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this.compressed = this.packets.write();
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break;
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case 'zip':
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// - ZIP [RFC1951]
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throw new Error("Compression algorithm ZIP [RFC1951] is not implemented.");
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break;
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case 'zlib':
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// - ZLIB [RFC1950]
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// TODO: need to implement this
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throw new Error("Compression algorithm ZLIB [RFC1950] is not implemented.");
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break;
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case 'bzip2':
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// - BZip2 [BZ2]
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// TODO: need to implement this
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throw new Error("Compression algorithm BZip2 [BZ2] is not implemented.");
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break;
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default:
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throw new Error("Compression algorithm unknown :" + this.type);
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break;
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}
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}
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};
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</code></pre>
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</article>
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</section>
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<h2><a href="index.html">Index</a></h2><h3>Modules</h3><ul><li><a href="module-armor.html">armor</a></li><li><a href="module-cleartext.html">cleartext</a></li><li><a href="module-config.html">config</a></li><li><a href="config.html">config/config</a></li><li><a href="localStorage.html">config/localStorage</a></li><li><a href="module-crypto.html">crypto</a></li><li><a href="cfb.html">crypto/cfb</a></li><li><a href="cipher.html">crypto/cipher</a></li><li><a href="aes.html">crypto/cipher/aes</a></li><li><a href="blowfish.html">crypto/cipher/blowfish</a></li><li><a href="cast5.html">crypto/cipher/cast5</a></li><li><a href="des.html">crypto/cipher/des</a></li><li><a href="twofish.html">crypto/cipher/twofish</a></li><li><a href="crypto.html">crypto/crypto</a></li><li><a href="hash.html">crypto/hash</a></li><li><a href="md5.html">crypto/hash/md5</a></li><li><a href="ripe-md.html">crypto/hash/ripe-md</a></li><li><a href="sha.html">crypto/hash/sha</a></li><li><a href="pkcs1.html">crypto/pkcs1</a></li><li><a href="public_key.html">crypto/public_key</a></li><li><a href="dsa.html">crypto/public_key/dsa</a></li><li><a href="elgamal.html">crypto/public_key/elgamal</a></li><li><a href="jsbn.html">crypto/public_key/jsbn</a></li><li><a href="rsa.html">crypto/public_key/rsa</a></li><li><a href="random.html">crypto/random</a></li><li><a href="signature.html">crypto/signature</a></li><li><a href="armor.html">encoding/armor</a></li><li><a href="base64.html">encoding/base64</a></li><li><a href="module-enums.html">enums</a></li><li><a href="module-key.html">key</a></li><li><a href="module-keyid.html">keyid</a></li><li><a href="keyring.html">keyring/keyring</a></li><li><a href="localstore.html">keyring/localstore</a></li><li><a href="module-message.html">message</a></li><li><a href="module-mpi.html">mpi</a></li><li><a href="module-openpgp.html">openpgp</a></li><li><a href="module-packet.html">packet</a></li><li><a href="compressed.html">packet/compressed</a></li><li><a href="literal.html">packet/literal</a></li><li><a href="marker.html">packet/marker</a></li><li><a href="one_pass_signature.html">packet/one_pass_signature</a></li><li><a href="packet.html">packet/packet</a></li><li><a href="packetlist.html">packet/packetlist</a></li><li><a href="public_key_.html">packet/public_key</a></li><li><a href="public_key_encrypted_session_key.html">packet/public_key_encrypted_session_key</a></li><li><a href="public_subkey.html">packet/public_subkey</a></li><li><a href="secret_key.html">packet/secret_key</a></li><li><a href="secret_subkey.html">packet/secret_subkey</a></li><li><a href="signature_.html">packet/signature</a></li><li><a href="sym_encrypted_integrity_protected.html">packet/sym_encrypted_integrity_protected</a></li><li><a href="sym_encrypted_session_key.html">packet/sym_encrypted_session_key</a></li><li><a href="symmetrically_encrypted.html">packet/symmetrically_encrypted</a></li><li><a href="trust.html">packet/trust</a></li><li><a href="user_attribute.html">packet/user_attribute</a></li><li><a href="userid.html">packet/userid</a></li><li><a href="module-s2k.html">s2k</a></li><li><a href="keyid.html">type/keyid</a></li><li><a href="mpi.html">type/mpi</a></li><li><a href="s2k.html">type/s2k</a></li><li><a href="module-util.html">util</a></li><li><a href="util.html">util/util</a></li></ul><h3>Classes</h3><ul><li><a href="JXG.Util.html">Util</a></li><li><a href="module-cleartext-CleartextMessage.html">CleartextMessage</a></li><li><a href="module-key-Key.html">Key</a></li><li><a href="module-key-SubKey.html">SubKey</a></li><li><a href="module-key-User.html">User</a></li><li><a href="module-message-Message.html">Message</a></li></ul>
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Documentation generated by <a href="https://github.com/jsdoc3/jsdoc">JSDoc 3.2.0</a> on Thu Jan 02 2014 13:02:39 GMT-0800 (PST)
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