Tod Beardsley
f1950c2fe1
Fixes #3289. This commit adds back the bit-struct library because in the end, it is useful for some modules, especially pello's. It's small and it has a nice license, so why not. After all, it /is/ useful for quicky application headers. Eventually, should be replaced by StructFu, but that requires some doc work on my part to get that transition in place. This also adds pello's DNS fuzzer module which makes use of BitStruct to create sometimes malformed-on-purpose DNS headers. Tested against 3 different DNS servers, caused one to reboot, so I'd say it works.
77 lines
1.9 KiB
Ruby
77 lines
1.9 KiB
Ruby
require 'bit-struct/bit-struct'
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class BitStruct
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# Class for nesting a BitStruct as a field within another BitStruct.
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# Declared with BitStruct.nest.
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class NestedField < Field
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def initialize(*args)
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super
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end
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# Used in describe.
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def self.class_name
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@class_name ||= "nest"
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end
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def class_name
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@class_name ||= nested_class.name[/\w+$/]
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end
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def nested_class
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@nested_class ||= options[:nested_class] || options["nested_class"]
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end
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def describe opts
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if opts[:expand]
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opts = opts.dup
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opts[:byte_offset] = offset / 8
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opts[:omit_header] = opts[:omit_footer] = true
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nested_class.describe(nil, opts) {|desc| yield desc}
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else
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super
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end
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end
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def add_accessors_to(cl, attr = name) # :nodoc:
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unless offset % 8 == 0
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raise ArgumentError,
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"Bad offset, #{offset}, for nested field #{name}." +
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" Must be multiple of 8."
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end
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unless length % 8 == 0
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raise ArgumentError,
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"Bad length, #{length}, for nested field #{name}." +
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" Must be multiple of 8."
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end
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offset_byte = offset / 8
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length_byte = length / 8
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last_byte = offset_byte + length_byte - 1
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byte_range = offset_byte..last_byte
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nc = nested_class
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cl.class_eval do
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define_method attr do ||
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nc.new(self[byte_range])
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end
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define_method "#{attr}=" do |val|
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if val.length != length_byte
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raise ArgumentError, "Size mismatch in nested struct assignment " +
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"to #{attr} with value #{val.inspect}"
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end
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if val.class != nc
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warn "Type mismatch in nested struct assignment " +
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"to #{attr} with value #{val.inspect}"
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end
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self[byte_range] = val
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end
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end
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end
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end
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end
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