Class: Rex::Poly::Machine::Solution

Inherits:
Object
  • Object
show all
Defined in:
lib/rex/poly/machine/machine.rb

Overview

A class to hold a solution for a Rex::Poly::Machine problem.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Solution

Returns a new instance of Solution.



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# File 'lib/rex/poly/machine/machine.rb', line 265

def initialize
  @permutations = ::Array.new
  @reg_state    = ::Array.new
  @offset       = 0
end

Instance Attribute Details

#offset ⇒ Object (readonly)

Returns the value of attribute offset.



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# File 'lib/rex/poly/machine/machine.rb', line 263

def offset
  @offset
end

Instance Method Details

#buffer ⇒ Object

Render the final buffer.



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# File 'lib/rex/poly/machine/machine.rb', line 310

def buffer
  previous_offset = nil
  count           = 0
  # perform an N-pass fixup for offsets...
  while( true ) do
    # If we cant get the offsets fixed within a fixed ammount of tries we return
    # nil to indicate failure and keep searching for a solution that will work.
    if( count > 64 )
      return nil
    end
    # Reset the solution offset so as to update it for this pass
    @offset = 0
    # perform a single pass to ensure we are using the correct offset values
    @permutations.each do | permutation |
      permutation.offset = @offset
      # Note: calling render() can throw both UndefinedPermutation and UnallowedPermutation exceptions,
      # however as we assume we only ever return the buffer once a final solution has been generated
      # we should never have either of those exceptions thrown.
      permutation.render
      @offset += permutation.length
    end
    # If we have generated two consecutive passes which are the same length we can stop fixing up the offsets.
    if( not previous_offset.nil? and @offset == previous_offset )
      break
    end
    count +=1
    previous_offset = @offset
  end
  # now a final pass to render the solution into the raw buffer
  raw = ''
  @permutations.each do | permutation |
    #$stderr.puts "#{permutation.name} - #{ "0x%08X (%d)" % [ permutation.offset, permutation.length] } "
    raw << permutation.render
  end
  return raw
end

#pop ⇒ Object

Pop off the last permutaion and register/variables state from this solution.



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# File 'lib/rex/poly/machine/machine.rb', line 298

def pop
  reg_available, reg_consumed, variables = @reg_state.pop
  permutation = @permutations.pop
  permutation.active = false
  permutation.offset = 0
  @offset -= permutation.length
  return permutation, reg_available, reg_consumed, variables
end

#push(permutation, reg_available, reg_consumed, variables) ⇒ Object

Push a new permutation onto this solutions permutations list and save the associated register/variables state



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# File 'lib/rex/poly/machine/machine.rb', line 287

def push( permutation, reg_available, reg_consumed, variables )
  permutation.active = true
  permutation.offset = @offset
  @offset += permutation.length
  @permutations.push( permutation )
  @reg_state.push( [ [].concat(reg_available), [].concat(reg_consumed), {}.merge(variables) ] )
end

#reset ⇒ Object

Reset this solution to an empty state.



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# File 'lib/rex/poly/machine/machine.rb', line 274

def reset
  @offset = 0
  @permutations.each do | permutation |
    permutation.active = false
    permutation.offset = 0
  end
  @permutations.clear
  @reg_state.clear
end