Module: RubySMB::Dcerpc::Ndr::PointerPlugin

Defined in:
lib/ruby_smb/dcerpc/ndr.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Instance Attribute Details

#ref_id ⇒ Object

Returns the value of attribute ref_id.



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# File 'lib/ruby_smb/dcerpc/ndr.rb', line 935

def ref_id
  @ref_id
end

Instance Method Details

#assign(val) ⇒ Object 



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# File 'lib/ruby_smb/dcerpc/ndr.rb', line 1043

def assign(val)
  if val == :null
    @ref_id = 0
  elsif is_alias?
    ref_field = fetch_alias_referent
    raise ArgumentError, "Referent of alias pointer does not exist: #{get_parameter(:ref_to)}" unless ref_field
    ref_field.assign(val)
  else
    instantiate_referent if is_null_ptr?
    super
  end
end

#do_num_bytes(struct_offset = 0, is_deferred: false) ⇒ Object 



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# File 'lib/ruby_smb/dcerpc/ndr.rb', line 1085

def do_num_bytes(struct_offset = 0, is_deferred: false)
  sum = 0
  if is_deferred
    if is_a?(NdrStruct) && self.class.superclass.has_conformant_array
      # align :max_count since it will be placed in front of the structure.
      # The structure itself will be properly aligned later.
      align = (4 - (struct_offset % 4)) % 4
      sum += align
    else
      sum += referent_bytes_align(struct_offset)
    end
  else
    # add ref_id size
    sum += 4

    parent_obj = nil
    if parent&.is_a?(ConstructedTypePlugin)
      parent_obj = parent.get_top_level_constructed_type
    end
    if parent_obj && @ref_id != 0 && !@standalone_ptr
      parent_obj.defer_ptr(self)
      # only return ref_id size, the actual referent size will be added later
      return sum
    end
  end
  unless (is_null_ptr? && !eval_parameter(:initial_value)) || is_alias?
    if is_a?(ArrayPlugin)
      sum += super(struct_offset + sum)
    else
      sum += super()
    end
  end

  sum
end

#do_read(io, is_deferred: false) ⇒ Object 



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# File 'lib/ruby_smb/dcerpc/ndr.rb', line 1019

def do_read(io, is_deferred: false)
  if is_deferred
    if is_a?(NdrStruct) && self.class.superclass.has_conformant_array
      # align :max_count since it will be placed in front of the structure.
      # The structure itself will be properly aligned later.
      align = (4 - (io.offset % 4)) % 4
      io.seekbytes(align)
    else
      io.seekbytes(referent_bytes_align(io.offset))
    end
  else
    @ref_id = io.readbytes(4).unpack('L<').first
    parent_obj = nil
    if parent&.is_a?(ConstructedTypePlugin)
      parent_obj = parent.get_top_level_constructed_type
    end
    if parent_obj && @ref_id != 0
      parent_obj.defer_ptr(self)
      return
    end
  end
  super(io) unless is_null_ptr? || is_alias?
end

#do_write(io, is_deferred: false) ⇒ Object 



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# File 'lib/ruby_smb/dcerpc/ndr.rb', line 995

def do_write(io, is_deferred: false)
  if is_deferred
    if is_a?(NdrStruct) && self.class.superclass.has_conformant_array
      # align :max_count since it will be placed in front of the structure.
      # The structure itself will be properly aligned later.
      align = (4 - (io.offset % 4)) % 4
      io.writebytes("\x00" * align)
    else
      io.writebytes("\x00" * referent_bytes_align(io.offset))
    end
  else
    write_ref_id(io)
    parent_obj = nil
    if parent&.is_a?(ConstructedTypePlugin)
      parent_obj = parent.get_top_level_constructed_type
    end
    if parent_obj && @ref_id != 0 && !@standalone_ptr
      parent_obj.defer_ptr(self)
      return
    end
  end
  super(io) unless (is_null_ptr? && !eval_parameter(:initial_value)) || is_alias?
end

#extend_top_level_class ⇒ Object 



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# File 'lib/ruby_smb/dcerpc/ndr.rb', line 949

def extend_top_level_class
  current = self
  loop do
    current.extend(TopLevelPlugin) unless current.is_a?(TopLevelPlugin)
    if current.parent.nil?
      current.set_top_level_ptr unless current.is_top_level_ptr
      break
    else
      current.unset_top_level_ptr if current.is_top_level_ptr
      current = current.parent
    end
  end
end

#fetch_alias_referent(current: parent, ref: get_parameter(:ref_to), name: nil) ⇒ Object 



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# File 'lib/ruby_smb/dcerpc/ndr.rb', line 1060

def fetch_alias_referent(current: parent, ref: get_parameter(:ref_to), name: nil)
  return if current.nil?
  if current.get_parameter(:ref_to) == ref
    raise ArgumentError.new(
      "Pointer alias refering to #{ref} cannot be found. This referent "\
      "should appears before the alias in the stream"
    )
  end
  return current if name == ref
  res = nil
  case current
  when ArrayPlugin
    current.each do |element|
      res = fetch_alias_referent(current: element, ref: ref, name: name)
      break if res
    end
  when BinData::Record, BinData::Struct
    current.each_pair do |name, field|
      res = fetch_alias_referent(current: field, ref: ref, name: name)
      break if res
    end
  end
  return res
end

#initialize_instance ⇒ Object 



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# File 'lib/ruby_smb/dcerpc/ndr.rb', line 937

def initialize_instance
  if @ref_id.nil?
    if eval_parameter(:initial_value)
      instantiate_referent
    else
      @ref_id = 0
    end
  end
  extend_top_level_class
  super
end

#insert(index, *objs) ⇒ Object 



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# File 'lib/ruby_smb/dcerpc/ndr.rb', line 1129

def insert(index, *objs)
  obj = super
  # If we just pushed a new element and it was a null pointer (ref_id==0),
  # we will initialize the ref_id to make sure it is not considered a null
  # pointer anymore
  if is_null_ptr? && is_a?(BinData::Array) && !empty?
    instantiate_referent
  end
  obj
end

#instantiate_referent ⇒ Object 



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# File 'lib/ruby_smb/dcerpc/ndr.rb', line 1121

def instantiate_referent
  @ref_id = INITIAL_REF_ID
end

#is_alias? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/ruby_smb/dcerpc/ndr.rb', line 1056

def is_alias?
  has_parameter?(:ref_to)
end

#is_null_ptr? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/ruby_smb/dcerpc/ndr.rb', line 1125

def is_null_ptr?
  @ref_id == 0
end

#referent_bytes_align(offset) ⇒ Object 



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# File 'lib/ruby_smb/dcerpc/ndr.rb', line 973

def referent_bytes_align(offset)
  align = self.class.superclass.default_parameters[:byte_align]
  align = eval_parameter(:referent_byte_align) unless align
  (align - (offset % align)) % align
end

#snapshot ⇒ Object 



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# File 'lib/ruby_smb/dcerpc/ndr.rb', line 963

def snapshot
  if is_alias?
    fetch_alias_referent
  elsif is_null_ptr? && !eval_parameter(:initial_value)
    :null
  else
    super
  end
end

#write_ref_id(io) ⇒ Object 



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# File 'lib/ruby_smb/dcerpc/ndr.rb', line 979

def write_ref_id(io)
  if is_alias?
    ref_field = fetch_alias_referent
    if ref_field
      if ref_field.class != self.class
        raise ArgumentError, "Pointer points to a different referent type: #{ref_field.class} (set to #{obj.class})"
      end
      @ref_id = ref_field.ref_id
    end
  elsif @ref_id != 0 || (is_null_ptr? && eval_parameter(:initial_value))
    @ref_id = INITIAL_REF_ID + self.class.pos
    self.class.increment_pos unless @standalone_ptr
  end
  io.writebytes([@ref_id].pack('L<'))
end