#
#--
# Ronin Exploits - A Ruby library for Ronin that provides exploitation and
# payload crafting functionality.
#
# Copyright (c) 2007-2009 Hal Brodigan (postmodern.mod3 at gmail.com)
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program 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 General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
#++
#

require 'ronin/exploits/exceptions/exploit_not_built'
require 'ronin/exploits/exceptions/restricted_char'
require 'ronin/exploits/exploit_target'
require 'ronin/exploits/exploit'
require 'ronin/chars/char_set'
require 'ronin/formatting/binary'

module Ronin
  module Exploits
    class BinaryExploit < Exploit

      objectify :ronin_binary_exploit

      # Targets of the exploit
      has n, :targets, :class_name => 'ExploitTarget'

      # Target index to use
      parameter :target_index,
                :value => 0,
                :description => 'default target index'

      # Custom target to use
      parameter :custom_target, :description => 'custom target'

      # String to pad extra space with
      parameter :pad, :value => 'A', :description => 'padding string'

      # Restricted characters that may not occurr in the built exploit
      attr_accessor :restricted

      # The built exploit
      attr_accessor :exploit

      #
      # Creates a new BinaryExploit object with the given _attributes_.
      #
      def initialize(attributes={})
        super(attributes)

        @restricted = Chars::CharSet.new(attributes[:restricted] || [])
      end

      #
      # Adds an ExploitTarget with the given _attributes_. If a _block_ is
      # given, it will be passed the ExploitTarget.
      #
      def target(attributes={},&block)
        @targets << ExploitTarget.first_or_create(attributes,&block)
      end

      #
      # Returns the selected target.
      #
      def selected_target
        (@custom_target || @targets[@target_index])
      end

      #
      # Creates a padded buffer of the specified _length_ using the
      # specified _padding_ data.
      #
      def pad_buffer(padding,length)
        padding = padding.to_s

        buffer = (padding * (length / padding.length))
        pad_remaining = (length % padding.length)

        unless pad_remaining==0
          buffer += padding[0,pad_remaining]
        end

        return buffer
      end

      #
      # Adds the given _chars_ to the restricted list of characters.
      #
      #   restrict 0x00, "\n"
      #   # => #<Ronin::Chars::CharSet: {"\0", "\n"}>
      #
      def restrict(*chars)
        @restricted += pattern
      end

      def build
        @exploit = ''
        return super
      end

      #
      # Verifies that the exploit is built and does not contain any
      # restricted characters.
      #
      def verify
        unless @exploit
          raise(ExploitNotBuilt,"cannot verify an unbuilt exploit",caller)
        end

        @restricted.each do |char|
          if @exploit.include?(char)
            raise(RestrictedChar,"Restricted character '#{char}' was found in the built exploit",caller)
          end
        end

        return super
      end

    end
  end
end