mirror of
https://github.com/rapid7/metasploit-framework
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301 lines
10 KiB
Ruby
301 lines
10 KiB
Ruby
class BitStruct
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class << self
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# Define a char string field in the current subclass of BitStruct,
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# with the given _name_ and _length_ (in bits). Trailing nulls _are_
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# considered part of the string.
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#
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# If a class is provided, use it for the Field class.
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# If a string is provided, use it for the display_name.
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# If a hash is provided, use it for options.
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#
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# Note that the accessors have COPY semantics, not reference.
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#
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def char(name, length, *rest)
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opts = parse_options(rest, name, CharField)
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add_field(name, length, opts)
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end
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alias string char
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BitStruct.autoload :CharField, "bit-struct/char-field"
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# Define a floating point field in the current subclass of BitStruct,
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# with the given _name_ and _length_ (in bits).
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#
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# If a class is provided, use it for the Field class.
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# If a string is provided, use it for the display_name.
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# If a hash is provided, use it for options.
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#
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# The <tt>:endian => :native</tt> option overrides the default of
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# <tt>:network</tt> byte ordering, in favor of native byte ordering. Also
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# permitted are <tt>:big</tt> (same as <tt>:network</tt>) and
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# <tt>:little</tt>.
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#
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def float name, length, *rest
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opts = parse_options(rest, name, FloatField)
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add_field(name, length, opts)
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end
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BitStruct.autoload :FloatField, "bit-struct/float-field"
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# Define an octet string field in the current subclass of BitStruct,
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# with the given _name_ and _length_ (in bits). Trailing nulls are
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# not considered part of the string. The field is accessed using
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# period-separated hex digits.
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#
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# If a class is provided, use it for the Field class.
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# If a string is provided, use it for the display_name.
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# If a hash is provided, use it for options.
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#
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def hex_octets(name, length, *rest)
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opts = parse_options(rest, name, HexOctetField)
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add_field(name, length, opts)
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end
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BitStruct.autoload :HexOctetField, "bit-struct/hex-octet-field"
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# Define a nested field in the current subclass of BitStruct,
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# with the given _name_ and _nested_class_. Length is determined from
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# _nested_class_.
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#
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# If a class is provided, use it for the Field class (i.e. <=NestedField).
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# If a string is provided, use it for the display_name.
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# If a hash is provided, use it for options.
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#
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# For example:
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#
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# class Sub < BitStruct
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# unsigned :x, 8
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# end
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#
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# class A < BitStruct
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# nest :n, Sub
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# end
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#
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# a = A.new
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#
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# p a # ==> #<A n=#<Sub x=0>>
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#
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# If a block is given, use it to define the nested fields. For example, the
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# following is equivalent to the above example:
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#
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# class A < BitStruct
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# nest :n do
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# unsigned :x, 8
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# end
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# end
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#
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# WARNING: the accessors have COPY semantics, not reference. When you call a
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# reader method to get the nested structure, you get a *copy* of that data.
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# Expressed in terms of the examples above:
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#
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# # This fails to set x in a.
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# a.n.x = 3
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# p a # ==> #<A n=#<Sub x=0>>
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#
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# # This works
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# n = a.n
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# n.x = 3
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# a.n = n
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# p a # ==> #<A n=#<Sub x=3>>
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#
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def nest(name, *rest, &block)
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nested_class = rest.grep(Class).find {|cl| cl <= BitStruct}
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rest.delete nested_class
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opts = parse_options(rest, name, NestedField)
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nested_class = opts[:nested_class] ||= nested_class
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unless (block and not nested_class) or (nested_class and not block)
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raise ArgumentError,
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"nested field must have either a nested_class option or a block," +
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" but not both"
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end
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unless nested_class
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nested_class = Class.new(BitStruct)
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nested_class.class_eval(&block)
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end
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opts[:default] ||= nested_class.initial_value.dup
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opts[:nested_class] = nested_class
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field = add_field(name, nested_class.bit_length, opts)
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field
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end
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alias struct nest
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BitStruct.autoload :NestedField, "bit-struct/nested-field"
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# Define an octet string field in the current subclass of BitStruct,
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# with the given _name_ and _length_ (in bits). Trailing nulls are
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# not considered part of the string. The field is accessed using
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# period-separated decimal digits.
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#
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# If a class is provided, use it for the Field class.
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# If a string is provided, use it for the display_name.
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# If a hash is provided, use it for options.
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#
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def octets(name, length, *rest)
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opts = parse_options(rest, name, OctetField)
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add_field(name, length, opts)
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end
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BitStruct.autoload :OctetField, "bit-struct/octet-field"
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# Define a padding field in the current subclass of BitStruct,
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# with the given _name_ and _length_ (in bits).
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#
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# If a class is provided, use it for the Field class.
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# If a string is provided, use it for the display_name.
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# If a hash is provided, use it for options.
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#
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def pad(name, length, *rest)
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opts = parse_options(rest, name, PadField)
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add_field(name, length, opts)
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end
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alias padding pad
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BitStruct.autoload :PadField, "bit-struct/pad-field"
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# Define a signed integer field in the current subclass of BitStruct,
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# with the given _name_ and _length_ (in bits).
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#
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# If a class is provided, use it for the Field class.
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# If a string is provided, use it for the display_name.
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# If a hash is provided, use it for options.
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#
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# SignedField adds the <tt>:fixed => divisor</tt> option, which specifies
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# that the internally stored value is interpreted as a fixed point real
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# number with the specified +divisor+.
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#
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# The <tt>:endian => :native</tt> option overrides the default of
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# <tt>:network</tt> byte ordering, in favor of native byte ordering. Also
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# permitted are <tt>:big</tt> (same as <tt>:network</tt>) and
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# <tt>:little</tt>.
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#
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def signed name, length, *rest
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opts = parse_options(rest, name, SignedField)
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add_field(name, length, opts)
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end
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BitStruct.autoload :SignedField, "bit-struct/signed-field"
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# Define a printable text string field in the current subclass of BitStruct,
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# with the given _name_ and _length_ (in bits). Trailing nulls are
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# _not_ considered part of the string.
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#
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# If a class is provided, use it for the Field class.
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# If a string is provided, use it for the display_name.
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# If a hash is provided, use it for options.
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#
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# Note that the accessors have COPY semantics, not reference.
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#
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def text(name, length, *rest)
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opts = parse_options(rest, name, TextField)
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add_field(name, length, opts)
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end
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BitStruct.autoload :TextField, "bit-struct/text-field"
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# Define a unsigned integer field in the current subclass of BitStruct,
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# with the given _name_ and _length_ (in bits).
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#
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# If a class is provided, use it for the Field class.
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# If a string is provided, use it for the display_name.
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# If a hash is provided, use it for options.
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#
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# UnsignedField adds the <tt>:fixed => divisor</tt> option, which specifies
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# that the internally stored value is interpreted as a fixed point real
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# number with the specified +divisor+.
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#
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# The <tt>:endian => :native</tt> option overrides the default of
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# <tt>:network</tt> byte ordering, in favor of native byte ordering. Also
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# permitted are <tt>:big</tt> (same as <tt>:network</tt>) and
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# <tt>:little</tt>.
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#
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def unsigned name, length, *rest
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opts = parse_options(rest, name, UnsignedField)
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add_field(name, length, opts)
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end
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BitStruct.autoload :UnsignedField, "bit-struct/unsigned-field"
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# Define a vector field in the current subclass of BitStruct,
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# with the given _name_.
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#
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# If a class is provided, use it for the Vector class, otherwise
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# the block must define the entry fields. The two forms looks like
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# this:
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#
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# class Vec < BitStruct::Vector
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# # these declarations apply to *each* entry in the vector:
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# unsigned :x, 16
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# signed :y, 32
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# end
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#
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# class Packet < BitStruct
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# # Using the Vec class defined above
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# vector :v, Vec, "a vector", :length => 5
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#
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# # equivalently, using an anonymous subclass of BitStruct::Vector
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# vector :v2, "a vector", :length => 5 do
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# unsigned :x, 16
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# signed :y, 32
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# end
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# end
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#
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# If a string is provided, use it for the display_name.
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# If a hash is provided, use it for options.
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# If a number is provided, use it for length (equivalent to using the
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# :length option).
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#
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# WARNING: the accessors have COPY semantics, not reference. When you call a
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# reader method to get the vector structure, you get a *copy* of that data.
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#
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# For example, to modify the numeric fields in a Packet as defined above:
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#
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# pkt = Packet.new
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# vec = pkt.v
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# entry = vec[2]
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# entry.x = 123
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# entry.y = -456
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# vec[2] = entry
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# pkt.v = vec
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#
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def vector(name, *rest, &block)
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opts = parse_options(rest, name, nil)
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cl = opts[:field_class]
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opts[:field_class] = VectorField
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unless (block and not cl) or (cl and not block)
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raise ArgumentError,
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"vector must have either a class or a block, but not both"
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end
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case
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when cl == nil
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vector_class = Class.new(BitStruct::Vector)
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vector_class.class_eval(&block)
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when cl < BitStruct
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vector_class = Class.new(BitStruct::Vector)
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vector_class.struct_class cl
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when cl < BitStruct::Vector
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vector_class = cl
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else raise ArgumentError, "Bad vector class: #{cl.inspect}"
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end
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vector_class.default_options default_options
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length = opts[:length] || rest.grep(Integer).first
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## what about :length => :lenfield
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unless length
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raise ArgumentError,
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"Must provide length as argument N or as option :length => N"
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end
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opts[:default] ||= vector_class.new(length) ## nil if variable length
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opts[:vector_class] = vector_class
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bit_length = vector_class.struct_class.round_byte_length * 8 * length
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field = add_field(name, bit_length, opts)
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field
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end
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BitStruct.autoload :VectorField, "bit-struct/vector-field"
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end
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autoload :Vector, "bit-struct/vector"
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end
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