Class: Arpie::Binary

Inherits:
Object
  • Object
show all
Extended by:
Arpie
Defined in:
lib/arpie/binary.rb,
lib/arpie/binary/fixed_type.rb

Overview

A Binary is a helper to convert arbitary bitlevel binary data to and from ruby Struct-lookalikes.

Here’s an example:

class Test < Arpie::Binary
  describe "I am a test"

  field :a, :uint8
  field :b, :bytes, :sizeof => :nint16
end

This will allow you to parse binary blocks consisting of:

  • a byte

  • a network-order int (16 bit)

  • a string which length’ is the given int

Rinse and repeat.

For all available data types, please look into the source file of this class at the bottom.

Writing new types is easy enough, (see BinaryType).

On confusing names:

Arpie uses the term binary to refer to on-the-wire data bit/byte binary format. A Binary (uppercase) is a object describing the format. If you’re reading binary, think “raw data”; if you’re reading Binary or object, think Arpie::Binary.

Another warning:

Do not use Kernel methods as field names. It’ll confuse method_missing. Example:

field :test, :uint8
=> in `test': wrong number of arguments (ArgumentError)

In fact, this is the reason while Binary will not let you define fields with with names like existing instance methods.

Defined Under Namespace

Classes: Field, Virtual

Constant Summary

Constants included from Arpie

MTU

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Arpie

bogon!, incomplete!

Constructor Details

#initialize ⇒ Binary

:startdoc:



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# File 'lib/arpie/binary.rb', line 63

def initialize
  @fields = {}
  @@fields[self.class] ||= []

  # set up our own class handlers, create anon classes, set up default values
  @@fields[self.class].each {|field|
    if field.inline_handler
      @fields[field.name] = field.inline_handler.new

    elsif field.type.is_a?(Class)
      @fields[field.name] = field.type.new

    elsif field.opts[:default]
      @fields[field.name] = field.opts[:default]
    end
  }
  if block_given?
    yield self
  end
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

#method_missing(m, *a) ⇒ Object 



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# File 'lib/arpie/binary.rb', line 100

def method_missing m, *a
  m.to_s =~ /^(.+?)(=?)$/ or super
  at = $1.to_sym
  if self.class.field?(at)
    if $2 == "="
      a.size == 1 or raise ArgumentError
      if !a[0].is_a?(Class) && inline = self.class.get_field(at)[3]
        a[0], __nil = inline.from(a[0], {})
      end
      @fields[at] = a[0]
    else
      @fields[at]
    end

  elsif self.class.virtual?(at)
    if $2 == "="
      raise ArgumentError
    else
      Binary.call_virtual(self, at)
    end

  else
    super
  end
end

Class Method Details

.__anonymous ⇒ Object 



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# File 'lib/arpie/binary.rb', line 55

def self.__anonymous
  @@anonymous[self]
end

.__anonymous=(x) ⇒ Object 



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# File 'lib/arpie/binary.rb', line 58

def self.__anonymous= x
  @@anonymous[self] = x
end

.add_hook(hook, handler) ⇒ Object 



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# File 'lib/arpie/binary.rb', line 314

def self.add_hook(hook, handler)
  @@hooks[self] ||= {}
  @@hooks[self][hook] ||= []
  @@hooks[self][hook] << handler
end

.binary_size(opts = {}) ⇒ Object 



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# File 'lib/arpie/binary.rb', line 302

def self.binary_size opts = {}
  @@fields[self] ||= []
  total = @@fields[self].inject(0) {|sum, field|
    klass = get_type_handler(field.type)
    sz = klass.binary_size(field.opts)
    sz or raise "cannot binary_size dynamic Binary definitions"
    sum + sz
  }

  total
end

.call_hooks(hook, *va) ⇒ Object 



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# File 'lib/arpie/binary.rb', line 320

def self.call_hooks(hook, *va)
  @@hooks[self] ||= {}
  @@hooks[self][hook] ||= []
  @@hooks[self][hook].each {|handler|
    va = *handler.call(*va)
  }
  va
end

.call_virtual(on_object, name) ⇒ Object 



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# File 'lib/arpie/binary.rb', line 126

def self.call_virtual(on_object, name)
  @@virtuals[on_object.class].select {|virtual|
    virtual.name == name
  }[0].handler.call(on_object)
end

.describe(text = nil) ⇒ Object

You can use this to provide a short description of this Binary. It will be shown when calling Binary.inspect. When called without a parameter, (non-recursively) print out a pretty description of this data type as it would appear on the wire.



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# File 'lib/arpie/binary.rb', line 188

def self.describe text = nil
  unless text.nil?
    @@description[self] = text
  else
    ret = []
    ret << "%-10s %s" % ["Binary:", @@description[self]]
    ret << ""

    sprf    = "%-10s %-25s %-15s %-15s %-15s %s"
    sprf_of = "%68s %s"
    if @@virtuals[self] && @@virtuals[self].size > 0
      ret << sprf % ["Virtuals:", "NAME", "TYPE", "WIDTH", "", "DESCRIPTION"]
      @@virtuals[self].each {|virtual|
        width = self.get_type_handler(virtual.type).binary_size(virtual.opts)
        ret << sprf % [ "",
          virtual.name,
          virtual.type,
          width,
          "",
          virtual.opts[:description]
        ]
      }
      ret << ""
    end
    if @@fields[self] && @@fields[self].size > 0
      ret << sprf % %w{Fields:   NAME TYPE WIDTH OF DESCRIPTION}
      @@fields[self].each {|field|
        width = self.get_type_handler(field.type).binary_size(field.opts)
        ret << sprf % [ "",
          field.name,
          field.type,
          (field.opts[:length] || field.opts[:sizeof] || width),
          field.opts[:of] ? field.opts[:of].inspect : "",
          field.opts[:description]
        ]
        ret << sprf_of % [ "",
          field.opts[:of_opts].inspect
        ] if field.opts[:of_opts]
      }
    end
    ret.join("\n")
  end
end

.describe_all_types ⇒ Object 



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# File 'lib/arpie/binary.rb', line 174

def self.describe_all_types
  ret = []
  strf = "%-15s %-8s %s"
  ret << strf % %w{TYPE WIDTH HANDLER}
  @@types.sort{|a,b| a[0].to_s <=> b[0].to_s}.each {|type, handler|
    ret << strf % [type.inspect, (handler.binary_size({}) rescue nil), handler.inspect]
  }
  ret.join("\n")
end

.f(*va, &b) ⇒ Object

Alias for field.



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# File 'lib/arpie/binary.rb', line 280

def self.f *va, &b
  field *va, &b
end

.field(name, type = nil, opts = {}, &block) ⇒ Object

Specify that this Binary has a field of type type. See the class documentation for usage.

Raises:

  • (ArgumentError) 


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# File 'lib/arpie/binary.rb', line 234

def self.field name, type = nil, opts = {}, &block
  @@fields[self] ||= []
  handler = get_type_handler(type)

  raise ArgumentError, "#{name.inspect} already exists as a virtual" if virtual?(name)
  raise ArgumentError, "#{name.inspect} already exists as a field" if field?(name)
  raise ArgumentError, "#{name.inspect} already exists as a instance method" if instance_methods.index(name.to_s)
  raise ArgumentError, "#{name.inspect}: cannot inline classes" if block_given? and type.class === Arpie::Binary

  @@fields[self].each {|field|
    raise ArgumentError, "#{name.inspect}: :optional fields cannot be followed by required fields" if
      field[:opts].include?(:optional)
  } unless opts[:optional]


  type.nil? && !block_given? and raise ArgumentError,
    "You need to specify an inline handler if no type is given."
  inline_handler = nil

  if block_given?
    inline_handler = Class.new(Arpie::Binary)
    inline_handler.__anonymous = [name, type, opts]
    inline_handler.instance_eval(&block)
  end

  if type.nil?
    type, inline_handler = inline_handler, nil
  end

  if handler.respond_to?(:required_opts)
    missing_required = handler.required_opts.keys - opts.keys
    raise ArgumentError, "#{self}: #{name.inspect} as type #{type.inspect} " +
      "requires options: #{missing_required.inspect}" if missing_required.size > 0
    handler.required_opts.each {|k,v|
      v.nil? and next
      v.call(opts[k]) or raise ArgumentError, "#{self}: Invalid value given for opt key #{k.inspect}."
    }
  end

  opts[:description] ||= opts[:desc] if opts[:desc]
  opts.delete(:desc)

  @@fields[self] << Field.new(name.to_sym, type, opts, inline_handler)
end

.field?(field) ⇒ Boolean

Returns true if this Binary has the named field.

Returns:

  • (Boolean) 


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# File 'lib/arpie/binary.rb', line 140

def self.field? field
  @@fields[self] or return false
  @@fields[self].select {|_field|
    _field.name == field
  }.size > 0
end

.from(binary, opts = {}) ⇒ Object

Parse the given binary, which is a string, and return an instance of this class. Will raise Arpie::EIncomplete when not enough data is available in binary to construct a complete Binary.



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# File 'lib/arpie/binary.rb', line 332

def self.from binary, opts = {}
  @@fields[self] ||= []
  binary = * self.call_hooks(:pre_from, binary)

  consumed_bytes = 0
  obj = new
  @@fields[self].each {|field| # name, klass, kopts, inline_handler|
    field.opts[:binary] = binary
    field.opts[:object] = obj
    handler = get_type_handler(field.type)

    attrib, consumed = binary, nil

    attrib, consumed =
      handler.from(binary[consumed_bytes .. -1], field.opts) rescue case $!
      when EIncomplete
        if field.opts[:optional]
          attrib, consumed = field.opts[:default], handler.binary_size(field.opts)
        else
          raise $!,
            "#{$!.to_s}, #{self}#from needs more data for " +
            "#{field.name.inspect}. (data: #{binary[consumed_bytes .. -1].inspect})"
        end
      when StreamError
        bogon! binary[consumed_bytes .. -1], "#{self}#from: #{field.name.inspect}: #{$!.to_s}"
      else
        raise
    end
    consumed_bytes += consumed

    obj.send((field.name.to_s + "=").to_sym, attrib)
    field.opts.delete(:binary)
    field.opts.delete(:object)
  }

  binary, obj, consumed_bytes = self.call_hooks(:post_from, binary, obj, consumed_bytes)
  [obj, consumed_bytes]
end

.get_field(field) ⇒ Object

Raises:

  • (ArgumentError) 


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# File 'lib/arpie/binary.rb', line 147

def self.get_field field
  @@fields[self] or raise ArgumentError, "No such field: #{field.inspect}"
  @@fields[self].each {|_field|
    _field.name == field and return _field
  }
  raise ArgumentError, "No such field: #{field.inspect}"
end

.get_type_handler(type) ⇒ Object

Returns the BinaryType handler class for type, which can be a symbol (:uint8), or a Arpie::Binary.



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# File 'lib/arpie/binary.rb', line 165

def self.get_type_handler type
  if type.class === Arpie::Binary
    type
  else
    @@types[type] or raise ArgumentError,
      "#{self}: No such field type: #{type.inspect}"
  end
end

.post_from(&handler) ⇒ Object

Add a hook that gets called after converting a Binary to wire format. Arguments to the handler: binary, object Note that all handlers need to return their arguemts as they were passed, as they will replace the original values.



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# File 'lib/arpie/binary.rb', line 435

def self.post_from &handler
  self.add_hook(:post_from, handler)
end

.post_to(&handler) ⇒ Object

Add a hook that gets called after converting a binary to Binary representation. Arguments to the handler: object, binary, consumed_bytes. Note that all handlers need to return their arguemts as they were passed, as they will replace the original values.



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# File 'lib/arpie/binary.rb', line 419

def self.post_to &handler
  self.add_hook(:post_to, handler)
end

.pre_from(&handler) ⇒ Object

Add a hook that gets called before converting a Binary to wire format. Arguments to the handler: object Note that all handlers need to return their arguemts as they were passed, as they will replace the original values.



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# File 'lib/arpie/binary.rb', line 427

def self.pre_from &handler
  self.add_hook(:pre_from, handler)
end

.pre_to(&handler) ⇒ Object

Add a hook that gets called before converting a binary to Binary representation. Arguments to the handler: binary Note that all handlers need to return their arguemts as they were passed, as they will replace the original values.



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# File 'lib/arpie/binary.rb', line 411

def self.pre_to &handler
  self.add_hook(:pre_to, handler)
end

.register_type(handler, *type_aliases) ⇒ Object

This registers a new type with this binary.



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# File 'lib/arpie/binary.rb', line 133

def self.register_type handler, *type_aliases
  type_aliases.each do |type|
    @@types[type] = handler
  end
end

.s(*va, &b) ⇒ Object

An alias for static.



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# File 'lib/arpie/binary/fixed_type.rb', line 36

def self.s *va, &b
  static *va, &b
end

.static(content, name = nil) ⇒ Object

Create a static field. This is an alias for:

field :name, :fixed, :value => content

If no name is specified, it is assumed that the user will never want to access it and a suitable one is autogenerated.



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# File 'lib/arpie/binary/fixed_type.rb', line 30

def self.static content, name = nil
  name ||= "static-%x" % content.hash
  field name, :fixed, :value => content
end

.to(object, opts = {}) ⇒ Object

Recursively convert the given Binary object to wire format.



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# File 'lib/arpie/binary.rb', line 372

def self.to object, opts = {}
  object.nil? and raise ArgumentError, "cannot #to nil"
  @@fields[self] ||= []
  r = []
  object = * self.call_hooks(:pre_to, object)

  @@fields[self].each {|field| # name, klass, kopts, inline_handler|
    field.opts[:object] = object
    handler = get_type_handler(field.type)
    val = object.send(field.name)

    if field.inline_handler
      val = val.to
    end

    # r << (val.respond_to?(:to) ? val.to(opts) : handler.to(val, kopts)) rescue case $!
    r << handler.to(val, field.opts) rescue case $!
      when StreamError
        raise $!, "#{self}#from: #{field.name.inspect}: #{$!.to_s}"
      else
        raise
    end
    field.opts.delete(:object)
  }

  r = r.join('')
  _obj, r = self.call_hooks(:post_to, object, r)
  r
end

.v(*va, &b) ⇒ Object

Alias for virtual.



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# File 'lib/arpie/binary.rb', line 298

def self.v *va, &b
  virtual *va, &b
end

.virtual(name, type, opts = {}, &handler) ⇒ Object

Set up a new virtual field

Raises:

  • (ArgumentError) 


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# File 'lib/arpie/binary.rb', line 285

def self.virtual name, type, opts = {}, &handler
  raise ArgumentError, "You need to pass a block with virtuals" unless block_given?
  raise ArgumentError, "#{name.inspect} already exists as a virtual" if virtual?(name)
  raise ArgumentError, "#{name.inspect} already exists as a field" if field?(name)
  raise ArgumentError, "#{name.inspect} already exists as a instance method" if instance_methods.index(name.to_s)

  @@virtuals[self] ||= []
  opts[:description] ||= opts[:desc]
  opts.delete(:desc)
  @@virtuals[self] << Virtual.new(name.to_sym, type, opts, handler)
end

.virtual?(virtual) ⇒ Boolean

Returns true if this Binary has the named virtual.

Returns:

  • (Boolean) 


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# File 'lib/arpie/binary.rb', line 156

def self.virtual? virtual
  @@virtuals[self] or return false
  @@virtuals[self].select {|_virtual|
    _virtual.name == virtual
  }.size > 0
end

Instance Method Details

#inspect ⇒ Object

:nodoc:



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# File 'lib/arpie/binary.rb', line 84

def inspect #:nodoc:
  desc = " " + @@description[self.class].inspect if @@description[self.class]
  # Anonymous is special
  klass = self.class.respond_to?(:__anonymous) && self.class.__anonymous ?
    "Anon#{self.class.__anonymous.inspect}" :
    self.class.to_s

  fields = []
  @@fields[self.class].each {|field|
    fields << "%s=>%s" % [field.name.inspect, @fields[field.name].inspect]
  }
  fields = '{' + fields.join(", ") + '}'

  "#<#{klass}#{desc} #{fields}>"
end

#to(opts = {}) ⇒ Object 



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# File 'lib/arpie/binary.rb', line 402

def to opts = {}
  self.class.to(self, opts)
end