// GPG4Browsers - An OpenPGP implementation in javascript
// Copyright (C) 2011 Recurity Labs GmbH
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
/**
* @class
* @classdesc Implementation of the Compressed Data Packet (Tag 8)
*
* RFC4880 5.6:
* The Compressed Data packet contains compressed data. Typically, this
* packet is found as the contents of an encrypted packet, or following
* a Signature or One-Pass Signature packet, and contains a literal data
* packet.
*/
function openpgp_packet_compressed() {
this.tagType = 8;
this.decompressedData = null;
/**
* Parsing function for the packet.
* @param {String} input Payload of a tag 8 packet
* @param {Integer} position Position to start reading from the input string
* @param {Integer} len Length of the packet or the remaining length of
* input at position
* @return {openpgp_packet_compressed} Object representation
*/
function read_packet (input, position, len) {
this.packetLength = len;
var mypos = position;
// One octet that gives the algorithm used to compress the packet.
this.type = input.charCodeAt(mypos++);
// Compressed data, which makes up the remainder of the packet.
this.compressedData = input.substring(position+1, position+len);
return this;
}
/**
* Decompression method for decompressing the compressed data
* read by read_packet
* @return {String} The decompressed data
*/
function decompress() {
if (this.decompressedData != null)
return this.decompressedData;
if (this.type == null)
return null;
switch (this.type) {
case 0: // - Uncompressed
this.decompressedData = this.compressedData;
break;
case 1: // - ZIP [RFC1951]
util.print_info('Decompressed packet [Type 1-ZIP]: ' + this.toString());
var compData = this.compressedData;
var radix = s2r(compData).replace(/\n/g,"");
// no header in this case, directly call deflate
var jxg_obj = new JXG.Util.Unzip(JXG.Util.Base64.decodeAsArray(radix));
this.decompressedData = unescape(jxg_obj.deflate()[0][0]);
break;
case 2: // - ZLIB [RFC1950]
util.print_info('Decompressed packet [Type 2-ZLIB]: ' + this.toString());
var compressionMethod = this.compressedData.charCodeAt(0) % 0x10; //RFC 1950. Bits 0-3 Compression Method
//Bits 4-7 RFC 1950 are LZ77 Window. Generally this value is 7 == 32k window size.
//2nd Byte in RFC 1950 is for "FLAGs" Allows for a Dictionary (how is this defined). Basic checksum, and compression level.
if (compressionMethod == 8) { //CM 8 is for DEFLATE, RFC 1951
// remove 4 bytes ADLER32 checksum from the end
var compData = this.compressedData.substring(0, this.compressedData.length - 4);
var radix = s2r(compData).replace(/\n/g,"");
//TODO check ADLER32 checksum
this.decompressedData = JXG.decompress(radix);
break;
} else {
util.print_error("Compression algorithm ZLIB only supports DEFLATE compression method.");
}
break;
case 3: // - BZip2 [BZ2]
// TODO: need to implement this
util.print_error("Compression algorithm BZip2 [BZ2] is not implemented.");
break;
default:
util.print_error("Compression algorithm unknown :"+this.type);
break;
}
util.print_debug("decompressed:"+util.hexstrdump(this.decompressedData));
return this.decompressedData;
}
/**
* Compress the packet data (member decompressedData)
* @param {Integer} type Algorithm to be used // See RFC 4880 9.3
* @param {String} data Data to be compressed
* @return {String} The compressed data stored in attribute compressedData
*/
function compress(type, data) {
this.type = type;
this.decompressedData = data;
switch (this.type) {
case 0: // - Uncompressed
this.compressedData = this.decompressedData;
break;
case 1: // - ZIP [RFC1951]
util.print_error("Compression algorithm ZIP [RFC1951] is not implemented.");
break;
case 2: // - ZLIB [RFC1950]
// TODO: need to implement this
util.print_error("Compression algorithm ZLIB [RFC1950] is not implemented.");
break;
case 3: // - BZip2 [BZ2]
// TODO: need to implement this
util.print_error("Compression algorithm BZip2 [BZ2] is not implemented.");
break;
default:
util.print_error("Compression algorithm unknown :"+this.type);
break;
}
this.packetLength = this.compressedData.length +1;
return this.compressedData;
}
/**
* Creates a string representation of the packet
* @param {Integer} algorithm Algorithm to be used // See RFC 4880 9.3
* @param {String} data Data to be compressed
* @return {String} String-representation of the packet
*/
function write_packet(algorithm, data) {
this.decompressedData = data;
if (algorithm == null) {
this.type = 1;
}
var result = String.fromCharCode(this.type)+this.compress(this.type);
return openpgp_packet.write_packet_header(8, result.length)+result;
}
/**
* Pretty printing the packet (useful for debug purposes)
* @return {String}
*/
function toString() {
return '5.6. Compressed Data Packet (Tag 8)\n'+
' length: '+this.packetLength+'\n'+
' Compression Algorithm = '+this.type+'\n'+
' Compressed Data: Byte ['+util.hexstrdump(this.compressedData)+']\n';
}
this.read_packet = read_packet;
this.toString = toString;
this.compress = compress;
this.decompress = decompress;
this.write_packet = write_packet;
};