##
# $Id$
##

##
# This file is part of the Metasploit Framework and may be subject to 
# redistribution and commercial restrictions. Please see the Metasploit
# Framework web site for more information on licensing and terms of use.
# http://metasploit.com/projects/Framework/
##


require 'msf/core'


###
#
# SingleByte
# ----------
#
# This class implements simple NOP generator for PowerPC
#
###
class Metasploit3 < Msf::Nop


	def initialize
		super(
			'Name'        => 'Simple',
			'Alias'       => 'ppc_simple',
			'Version'     => '$Revision$',
			'Description' => 'Simple NOP generator',
			'Author'      => 'hdm',
			'License'     => MSF_LICENSE,
			'Arch'        => ARCH_PPC)

		register_advanced_options(
			[
				OptBool.new('RandomNops', [ false, "Generate a random NOP sled", true ])
			], self.class)
	end


	def generate_sled(length, opts)
		
		badchars = opts['BadChars'] || ''
		random   = opts['Random']   || datastore['RandomNops']
		
		if( random and random.match(/^(t|y|1)/i) )
			1.upto(1024) do |i|
				regs_d = (rand(0x8000 - 0x0800) + 0x0800).to_i
				regs_b = [regs_d].pack('n').unpack('B*')[0][1, 15]
				flag_o = rand(2).to_i
				flag_r = rand(2).to_i
				
				pcword = ["011111#{regs_b}#{flag_o}100001010#{flag_r}"].pack("B*")
				failed = false
				
				pcword.each_byte do |c|
					failed = true if badchars.include?(c.chr)
				end
				
				next if failed
				
				return (pcword * (length / 4))[0, length]
			end
		end
		
		return ("\x60" * length)[0, length]
	end

end