metasploit-framework/lib/rex/zip/blocks.rb

##
# $Id$
##

module Rex
module Zip


#
# This structure holds the following data pertaining to a Zip entry's data.
#
# data crc
# compressed size
# uncompressed size
#
class CompInfo

	def initialize(crc, compsz, uncompsz)
		@crc, @compsz, @uncompsz = crc, compsz, uncompsz
	end

	def pack
		[ @crc, @compsz, @uncompsz ].pack('VVV')
	end

end


#
# This structure holds the following data pertaining to a Zip entry.
#
# general purpose bit flag
# compression method
# modification time
# modification date
#
class CompFlags

	attr_accessor :compmeth

	def initialize(gpbf, compmeth, timestamp)
		@gpbf = gpbf
		@compmeth = compmeth
		@mod_time = ((timestamp.hour << 11) | (timestamp.min << 5) | (timestamp.sec))
		@mod_date = (((timestamp.year - 1980) << 9) | (timestamp.mon << 5) | (timestamp.day))
	end

	def pack
		[ @gpbf, @compmeth, @mod_time, @mod_date ].pack('vvvv')
	end

end



#
# This structure is sometimes stored after the file data and used
# instead of the fields within the Local File Header.
#
class DataDesc

	SIGNATURE = 0x8074b50

	def initialize(compinfo)
		@compinfo = compinfo
	end

	def pack
		ret = [ SIGNATURE ].pack('V')
		ret << @compinfo.pack
		ret
	end

end


#
# This structure records the compression data and flags about
# a Zip entry to a file.
#
class LocalFileHdr

	SIGNATURE = 0x4034b50

	def initialize(entry)
		@entry = entry
	end

	def pack
		path = @entry.relative_path

		ret = [ SIGNATURE, ZIP_VERSION ].pack('Vv')
		ret << @entry.flags.pack
		ret << @entry.info.pack
		ret << [ path.length, @entry.xtra.length ].pack('vv')
		ret << path
		ret << @entry.xtra
		ret
	end

end


#
# This structure holds all of the information about a particular Zip Entry
# as it is contained within the central directory.
#
class CentralDir

	SIGNATURE = 0x2014b50

	def initialize(entry, offset)
		@entry = entry
		@disknum_start = 0
		@attr_int = 0
		@attr_ext = 0x20
		@hdr_offset = offset
	end

	def pack
		path = @entry.relative_path

		ret = [ SIGNATURE, ZIP_VERSION ].pack('Vv')
		ret << [ ZIP_VERSION ].pack('v')
		ret << @entry.flags.pack
		ret << @entry.info.pack
		arr = []
		arr << path.length
		arr << @entry.xtra.length
		arr << @entry.comment.length
		arr << @disknum_start
		arr << @attr_int
		arr << @entry.attrs
		arr << @hdr_offset
		ret << arr.pack('vvvvvVV')
		ret << path
		ret << @entry.xtra
		ret << @entry.comment
		# digital signature not supported
		ret
	end

end


#
# This structure is written after the per-entry central directory records to
# provide information about the archive as a whole.
#
class CentralDirEnd

	SIGNATURE = 0x6054b50

	def initialize(ncfd, cfdsz, offset, comment=nil)
		@disk_no = 0
		@disk_dir_start = 0
		@ncfd_this_disk = ncfd
		@ncfd_total = ncfd
		@cfd_size = cfdsz
		@start_offset = offset
		@comment = comment
		@comment ||= ''
	end


	def pack
		arr = []
		arr << SIGNATURE
		arr << @disk_no
		arr << @disk_dir_start
		arr << @ncfd_this_disk
		arr << @ncfd_total
		arr << @cfd_size
		arr << @start_offset
		arr << @comment.length
		(arr.pack('VvvvvVVv') + @comment)
	end

end

end
end