API Reference

Overview

This describes the API available from binary-data. It is organized in the following sections, depending on different demands: using binary data in a tool, extending with a custom binary format, and the internal API.

Class hierarchy

The class hierarchy is rooted in <frame>. Several direct subclasses exist, some are open and may be subclassed. Only those combinations of direct subclasses which were needed until now are defined (there might be need for other combinations in the future).

<frame> Abstract Class
Discussion

The abstract superclass of all frames, several generic functions are defined on this class.

Superclasses

<object>

Operations

<leaf-frame> Abstract Class
Discussion

The abstract superclass of all frames without any further structure.

Superclasses

<frame>

Operations

<fixed-size-frame> Abstract Class
Discussion

The abstract superclass of all frames with a static length. The specialization of frame-size calls field-size on the object class of the given instance.

Superclasses

<frame>

<variable-size-frame> Abstract Class
Discussion

The abstract superclass of all frames with a variable length.

Superclasses

<frame>

<translated-frame> Abstract Class
Discussion

The abstract superclass of all frames with a conversion into a native Dylan type.

Superclasses

<frame>

<untranslated-frame> Abstract Class
Discussion

Abstract superclass of all frames with a custom class instance.

Superclasses

<frame>

<fixed-size-untranslated-frame> Abstract Class
Discussion

Abstract superclass for fixed sized frames without a translation

Superclasses

<fixed-size-frame>, <untranslated-frame>

<variable-size-untranslated-frame> Abstract Class
Discussion

Abstract superclass for variable sized frames without a translation. This is the direct superclass of <container-frame>.

Superclasses

<variable-size-frame>, <untranslated-frame>

<fixed-size-translated-leaf-frame> Open Abstract Class
Discussion

Superclass of all fixed size leaf frames with a translation, mainly used for bit vectors represented as Dylan <integer>

Superclasses

<leaf-frame>, <fixed-size-frame>, <translated-frame>

<variable-size-translated-leaf-frame> Open Abstract Class
Discussion

Superclass of all variable size leaf frames with a translation (currently unused)

Superclasses

<leaf-frame>, <variable-size-frame>, <translated-frame>

<fixed-size-untranslated-leaf-frame> Open Abstract Class
Discussion

Superclass of all fixed size leaf frames without a translation, mainly used for byte vectors (IP addresses, MAC address, …), see its subclass <fixed-size-byte-vector-frame>.

Superclasses

<leaf-frame>, <fixed-size-untranslated-frame>

<variable-size-untranslated-leaf-frame> Open Abstract Class
Discussion

Superclass of all variable size leaf frames without a translation (for example class <raw-frame> and class <externally-delimited-string>)

Superclasses

<leaf-frame>, <variable-size-untranslated-frame>

<null-frame> Class
Discussion

A concrete zero size leaf frame without a translation. This frame type can be used as one of the types of a variably-typed field to make the field optional. A field with a type <null-frame> is considered to be missing from the container frame. Conversion of a <null-frame> to string or vice versa is not supported (because it wouldn’t make much sense).

Superclasses

<fixed-size-untranslated-leaf-frame>

<container-frame> Open Abstract Class

Superclass of all binary data definitions using the define binary-data macro.

Superclasses

<variable-size-untranslated-frame>

Operations

<header-frame> Open Abstract Class

Superclass of all binary data definitions which support layering, thus have a header and payload.

Superclasses

<container-frame>

Discussion

The method payload projects the payload of the header frame. The method payload-setter is also defined. The specialized method fixup! calls fixup! on the payload of the header frame instance.

Operations

  • payload

  • payload-setter

  • fixup!

<variably-typed-container-frame> Open Abstract Class

Superclass of all binary data definitions which have an abstract header followed by more fields. In the header a specific <layering-field> determines which subclass to instantiate.

Superclasses

<container-frame>

Tool API

Parsing Frames

parse-frame Open Generic function

Parses the given binary packet as frame-type, resulting in an instance of the frame-type and the number of consumed bits.

Signature

parse-frame frame-type packet #rest rest #key #all-keys => result consumed-bits

Parameters

  • frame-type – Any subclass of <frame>.

  • packet – The byte vector as <sequence>.

  • rest (#rest) – An instance of <object>.

Values

  • result – An instance of the given frame-type.

  • consumed-bits – The number of bits consumed as <integer>

read-frame Open Generic function

Converts a given string to an instance of the given leaf frame type.

Signature

read-frame frame-type string => frame

Parameters

  • frame-type – An instance of subclass(<leaf-frame>).

  • string – An instance of <string>.

Values

  • frame – An instance of <object>.

Assembling Frames

assemble-frame Generic function

Produces a binary vector representing this frame. All field fixup functions are called.

Signature

assemble-frame frame => packet

Parameters

  • frame – An instance of <frame>.

Values

  • packet – An instance of <object>.

Information about Frames

frame-size Open Generic function

Returns the length in bits for the given frame.

Signature

frame-size frame => length

Parameters

  • frame – An instance of <frame>.

Values

  • length – The size in bits, an instance of <integer>.

summary Open Generic function

Returns a human-readable customizable (in binary-data-definer) string, which summarizes the frame.

Signature

summary frame => summary

Parameters

  • frame – An instance of <frame>.

Values
packet Open Generic function

Underlying byte vector of the given <container-frame>.

Signature

packet frame => byte-vector

Parameters
Values

  • byte-vector – An instance of <byte-sequence>.

parent Sealed Generic function

If the frame is a payload of another layer, returns the frame of the upper layer, false otherwise.

Signature

parent frame => parent-frame

Parameters
Values

Information about Frame Types

fields Open Generic function

Returns a vector of <field> for the given <container-frame>

Signature

fields frame-type => fields

Parameters
Values

Note

Current API also allows instances of <container-frame>, should be revised

frame-name Open Generic function

Returns the name of the frame type.

Signature

frame-name frame-type => name

Parameters
Values

  • name – A <string> with the human-readable frame name.

Note

Current API also allows instances of <container-frame>, should be revised

Fields

Syntactic sugar in the define binary-data domain-specific language instantiates these fields.

<field> Abstract Class

The abstract superclass of all fields.

Superclasses

<object>

Init-Keywords

  • name – The name of this field.

  • fixup – A unary Dylan function computing the value of this field, used if no default is supplied and none provided by the client, defaults to #f.

  • init-value – The default value if the client did not provide any, default $unsupplied.

  • static-end – A Dylan expression determining the end, defaults to $unknown-at-compile-time.

  • static-length – A Dylan expression determining the length, defaults to $unknown-at-compile-time.

  • static-start – A Dylan expression determining the start, defaults to $unknown-at-compile-time.

  • dynamic-end – A unary Dylan function computing the end, defaults to #f.

  • dynamic-length – A unary Dylan function computing the length, defaults to #f.

  • dynamic-start – A unary Dylan function computing the start, defaults to #f.

  • getter – The getter method to extract this fields value out of a concrete frame.

  • setter – The setter method to set this fields to a concrete value in a concrete frame.

  • index – An <integer> which is an index of this field in its <container-frame>.

Discussion

All keyword arguments correspond to a slot, which can be accessed.

Operations

  • field-name(<field>)

  • fixup-function(<field>)

  • init-value(<field>)

  • static-start(<field>)

  • static-length(<field>)

  • static-end(<field>)

  • getter(<field>)

  • setter(<field>)

See also

<variably-typed-field> Class

The class for fields of dynamic type.

Superclasses

<field>

Init-Keywords

  • type-function – A unary Dylan function computing the type of the field, defaults to payload-type.

See also

<statically-typed-field> Abstract Class

The abstract superclass of all statically typed fields.

Superclasses

<field>

Init-Keywords

  • type – The static type, a subclass of <frame>.

Operations

  • type(<statically-typed-field>)

Note

restrict type in source code!

<single-field> Class

The common field. Nothing interesting going on here.

Superclasses

<statically-typed-field>

<enum-field> Class

An enumeration field to map <integer> to <symbol>.

Superclasses

<single-field>

Init-Keywords

  • mapping – A mapping from keys to values as <collection>.

<layering-field> Class

The layering field is used in <header-frame> and <variably-typed-container-frame> to determine the concrete type of the payload or which subclass to use.

Superclasses

<single-field>

Discussion

The fixup-function slot is bound to use the available layering information. No need to specify a fixup.

<repeated-field> Abstract Class

Abstract superclass of repeated fields. The init-value slot is bound to #().

Superclasses

<statically-typed-field>

<count-repeated-field> Class

A repeated field whose number of repetitions is determined externally.

Superclasses

<repeated-field>

Init-Keywords

  • count – A unary function returning the number of occurences.

<self-delimited-repeated-field> Class

A repeated field whose end is determined internally.

Superclasses

<repeated-field>

Init-Keywords

  • reached-end? – A unary function returning a <boolean>.

Layering of frames

payload-type Function

The type of the payload, It is just a wrapper around lookup-layer, which returns <raw-frame> if lookup-layer returned false.

Signature

payload-type frame => payload-type

Parameters
Values

  • payload-type – An instance of <type>.

lookup-layer Open Generic function

Given a frame-type and a key, returns the type of the payload.

Signature

lookup-layer frame-type key => payload-type

Parameters
Values

  • payload-type – The resulting type, an instance of false-or(<class>).

reverse-lookup-layer Open Generic function

Given a frame type and a payload, returns the value for the layering field.

Signature

reverse-lookup-layer frame-type payload => layering-value

Parameters

  • frame-type – Any subclass of <frame>.

  • payload – Any <frame> instance.

Values

  • value – The returned layering field value, an <integer>.

Note

Check whether it can work with other types than integers

Database of Binary Data Formats

Note

Rename to $binary-data-registry or similar. Also, narrow types for the functions in this section.

$protocols Constant

A hash table with all defined binary formats. Insertion is done by a call of define binary-data.

Type

<table>

Value

Mapping of <symbol> to subclasses of <container-frame>.

find-protocol Function

Looks for the given name in the hashtable $protocols. Signals an error if no protocol with the given name can be found.

Signature

find-protocol frame-name => frame-type frame-name

Parameters

  • frame-name – An instance of <string>.

Values

  • frame-type – The frame type for the requested frame name, an instance of <class>.

  • frame-name – The name under which the frame is known in the registry, an instance of <string>.

find-protocol-field Function

Queries a field by name in a given binary data format. Errors if no such field is known in the binary data format.

Signature

find-protocol-field frame-type field-name => field

Parameters

  • frame-type – The type of a frame, an instance of <class>.

  • field-name – The name of a field, an instance of <string>.

Values

  • field – An instance of <field>.

Utilities

hexdump Generic function

Prints the given data in hexadecimal on the given stream.

Signature

hexdump stream data => ()

Parameters

  • stream – An instance of <stream>.

  • data – An instance of <sequence>.

Discussion

Prints 8 bytes separated by a whitespace in hexadecimal, followed by two whitespaces, and another 8 bytes.

If the given data has more than 16 elements, it prints multiple lines, and prefix each with a line number (as 16 bit hexadecimal).

byte-offset Function

Computes the number of bytes for a given number of bits. A synonym for rcurry(ash, 3).

Signature

byte-offset bits => bytes

Parameters
Values
bit-offset Function

Computes the number of bits which do not fit into a byte for a given number of bits. A synonym for curry(logand, 7).

Signature

bit-offset bits => bits-not-in-byte

Parameters
Values

  • bits-not-in-byte – An <integer> between 0 and 7.

byte-aligned Function

Checks that the given number of bits can be represented in full bytes, otherwise signals an <alignment-error>.

Signature

byte-aligned bits

Parameters

  • bits – An instance of <integer>.

data Generic function

Returns the underlying byte vector of a wrapper object, used for several untranslated leaf frames.

Signature

data (object) => (#rest results)

Parameters

  • object – An instance of <object>.

Values

  • #rest results – An instance of <object>.

Note

should be removed from the API, or become internal

Errors

<out-of-bound-error> Class
Superclasses

<error>

<out-of-range-error> Class
Superclasses

<error>

<malformed-data-error> Class
Superclasses

<error>

<parse-error> Class
Superclasses

<error>

<inline-layering-error> Class
Superclasses

<error>

<missing-inline-layering-error> Class
Superclasses

<error>

Extension API

Extending Binary Data Formats

This domain-specific language defines a subclass of <container-frame>, and lots of boilerplate.

define binary-data Defining Macro
Macro Call

define [abstract] binary-data *binary-format-name* ([*super-binary-format*])
  [summary *summary*] [;]
  [over *over-spec* *] [;]
  [length *length-expression*] [;]
  [*field-spec*] [;]
end

Parameters

  • binary-format-name – A standard Dylan class name.

  • super-binary-format – A standard Dylan name, used superclass.

  • summary – A Dylan expression consisting of a format-string and a list of arguments.

  • over-spec – A pair of binary format and value.

  • length-expression – A Dylan expression computing the length of a frame instance.

  • field-spec – A list of fields for this binary format.

Discussion

Defines the binary data class binary-data-name, which is a subclass of super-binary-format. In the body some syntactic sugar for specializing the pretty printer (summary specializes summary), providing a custom length implementation (length specializes container-frame-size), and provide binary format layering information via over-spec (<layering-field>). The remaining body is a list of field-spec. Each field-spec line corresponds to a slot in the defined class. Additionally, each field-spec instantiates an object of <field> to store the static metadata. The vector of fields is available via the method fields.

summary: *format-string* *format-arguments*

This generates a method implementation for summary. Each format-arguments is applied to the frame instance.

over-spec: *over-binary-format* *layering-value*

The over-binary-format should be a subclass of <header-frame> or <variably-typed-container-frame>. The layering-value will be registered for the specified over-binary-format.

field-spec: [*field-attribute*] field *field-name* [:: *field-type*] [= *default-value*], [*keyword-arguments* *] [;]

field-attribute: variably-typed | layering | repeated | enum

mapping: { *key* <=> *value* }

  • field-name: Each field has a unique field-name, which is used as name for the getter and setter methods

  • field-type: The field-type can be any subclass of <frame>, required unless variably-typed attribute provided.

  • default-value: The default-value should be an instance of the given field-type.

  • field-attribute: Syntactic sugar for some common patterns is available via attributes.

  • keyword-arguments: Depending on the field type, various keywords are supported. Lots of values are standard Dylan expressions, where the current frame object is implicitly bound to frame, indicated by frame-expression.

    • fixup: A frame-expression computing the field value if no default was supplied, and the client didn’t provide one (handy for length fields).

    • start: A frame-expression computing the start bit of the field in the frame.

    • end: A frame-expression computing the end bit of the field in the frame.

    • length: A frame-expression computing the length of the field.

    • static-start: A Dylan expression stating the start of the field in the frame.

    • static-end: A Dylan expression stating the end of the field in the frame.

    • static-length: A Dylan expression stating the length of the field.

    • type-function: A frame-expression computing the type of this <variably-typed-field>.

    • count: A frame-expression computing the amount of repetitions of this <count-repeated-field>.

    • reached-end?: A frame-expression returning a <boolean> whether this <self-delimited-repeated-field> has reached its end.

    • mappings: A mapping for <enum-field> between values and <symbol>

The list of fields is instantiated once for each binary data definition. If a static start offset, length, and end offset can be trivially computed (using constant folding), this is done during macro processing.

Several generic functions can be specialized on the binary-format-name for custom behaviour:

Note

rename start, end, length to dynamic-start, dynamic-end, dynamic-length

Note

Check whether those field attributes compose in some way

fixup! Open Generic function

Fixes data in an assembled container frame.

Signature

fixup! frame => ()

Parameters
Discussion

Used for post-assembly of certain fields, such as checksum calculations in IPv4, ICMP, TCP frames, compression of domain names in DNS fragments.

Defining a Custom Leaf Frame

A common structure in binary data formats are subsequent ranges of bits or bytes, each with a different meaning. There are some macros available to define frame types of common patterns.

field-size Open Generic function

Returns the static size of a given frame type. Should be specialized for custom fixed sized frames.

Signature

field-size frame => length

Parameters

  • frame – Any subclass of <frame>.

Values

  • length – The bit size of the frame type <number>.

high-level-type Open Generic function

For translated frames, return the native Dylan type. Otherwise identity.

Signature

high-level-type frame-type => type

Parameters

  • frame-type – An instance of subclass(<frame>).

Values

  • type – An instance of <type>.

assemble-frame-into Open Generic function

Shuffle the bits in the given packet so that the frame is encoded correctly.

Signature

assemble-frame-into frame packet => length

Parameters
Values
assemble-frame-into-as Open Generic function

Shuffle the bits in the given packet so that the frame is encoded correctly as the given frame-type.

Signature

assemble-frame-into-as frame-type frame packet => length

Parameters
Values
define n-bit-unsigned-integer Defining Macro

Describes an <integer> represented by a bit vector of arbitrary size.

Macro Call

define n-bit-unsigned-integer (*class-name* ; *bits* )
end

Parameters

  • class-name – A Dylan class name which is defined by this macro.

  • bits – The number of bits represented by this frame.

Discussion

Defines the class class-name with <unsigned-integer-bit-frame> as its superclass.

There are several predefined classes of the form <Kbit-unsigned-integer> with K between 1 and 15, and 20.

Operations
define n-byte-unsigned-integer Defining Macro

Describes an <integer> represented by a byte vector of arbitrary size and encoding (little or big endian).

Macro Call

define n-byte-unsigned-integer (*class-name-prefix* ; *bytes*)
end

Parameters

  • class-name-prefix – A prefix for the class name which is defined by this macro.

  • bytes – The number of bytes represented by this frame.

Discussion

Defines the classes class-name-prefix -big-endian-unsigned-integer> (superclass <big-endian-unsigned-integer-byte-frame> and class-name-prefix -little-endian-unsigned-integer> (superclass <little-endian-unsigned-integer-byte-frame>.

The following classes are predefined: <2byte-big-endian-unsigned-integer>, <2byte-little-endian-unsigned-integer>, <3byte-big-endian-unsigned-integer>, and <3byte-little-endian-unsigned-integer>.

Operations
define n-byte-vector Defining Macro

Defines a class with an underlying fixed size byte vector.

Macro Call

define n-byte-vector (*class-name* , *bytes*)
end

Parameters

  • class-name – A standard Dylan class name.

  • bytes – The number of bytes represented by this frame.

Discussion

Defines the class class-name, as a subclass of <fixed-size-byte-vector-frame>. Calls define leaf-frame-constructor with the given class-name (without surrounding angle brackets).

Operations
define leaf-frame-constructor Defining Macro

Defines constructors for a given name.

Macro Call

define leaf-frame-constructor (*constructor-name*)
end

Parameters

  • constructor-name – name of the constructor.

Discussion

Defines the generic function constructor-name and three specializations:

Operations

  • constructor-name <byte-vector> calls parse-frame

  • constructor-name <collection>, converts the <collection> into a <byte-vector> and calls constructor-name.

  • constructor-name <string>, which calls read-frame.

Predefined Leaf Frames

<unsigned-integer-bit-frame> Abstract Class

The superclass of all bit frames, concrete classes are defined with the define n-bit-unsigned-integer.

Superclasses

<fixed-size-translated-leaf-frame>

Operations

See also

<boolean-bit> Class

A single bit, at the Dylan level a <boolean>.

The high-level-type returns <boolean>. The field-size returns 1.

Superclasses

<fixed-size-translated-leaf-frame>

<unsigned-byte> Class

A single byte, represented as a <byte>.

Operations

Superclasses

<fixed-size-translated-leaf-frame>

<variable-size-byte-vector> Abstract Class

A byte vector of arbitrary size, provided externally.

Superclasses

<variable-size-untranslated-leaf-frame>

<externally-delimited-string> Class

A <string> of a certain length, externally delimited. The conversion method as is specialised on <string> and <externally-delimited-string>.

Superclasses

<variable-size-byte-vector>

Note

should be a variable-size translated leaf frame, if that is possible.

<raw-frame> Class

The bottom of the type hierarchy: if nothing is known, a <raw-frame> is all you can have. hexdump can be used to inspect the frame contents.

Superclasses

<variable-size-byte-vector>

<fixed-size-byte-vector-frame> Open Abstract Class

A vector of any amount of bytes with a custom representation. Used amongst others for IP addresses, MAC addresses

Superclasses

<fixed-size-untranslated-leaf-frame>

Init-Keywords

  • data – The underlying byte vector.

Operations

See also

<big-endian-unsigned-integer-byte-frame> Abstract Class

A frame representing an <integer> of a certain size, depending on the size of the underlyaing byte vector.

The macro define n-byte-unsigned-integer-definer defines subclasses with a certain size.

Superclasses

<fixed-size-translated-leaf-frame>

Operations

See also

<little-endian-unsigned-integer-byte-frame> Abstract Class

A frame representing an <integer> of a certain size, depending on the size of the underlying byte vector.

The macro define n-byte-unsigned-integer-definer defines subclasses with a certain size.

Superclasses

<fixed-size-translated-leaf-frame>

Operations

See also

32 Bit Frames

The <integer> type in Dylan is represented by only 30 bits, thus 32 bit frames which should be represented as a <number> require a workaround. The workaround consists of using <fixed-size-byte-vector-frame> and converting to <double-float> values.

Note

This hack is awful and should be replaced by native 32 bit integers, or machine words.

<big-endian-unsigned-integer-4byte> Class
Superclasses

<fixed-size-byte-vector-frame>

<little-endian-unsigned-integer-4byte> Class
Superclasses

<fixed-size-byte-vector-frame>

big-endian-unsigned-integer-4byte Generic function
Signature

big-endian-unsigned-integer-4byte (data) => (#rest results)

Parameters

  • data – An instance of <object>.

Values

  • #rest results – An instance of <object>.

little-endian-unsigned-integer-4byte Generic function
Signature

little-endian-unsigned-integer-4byte (data) => (#rest results)

Parameters

  • data – An instance of <object>.

Values

  • #rest results – An instance of <object>.

byte-vector-to-float-be Function
Signature

byte-vector-to-float-be (bv) => (res)

Parameters

  • bv – An instance of <stretchy-byte-vector-subsequence>.

Values

  • res – An instance of <float>.

byte-vector-to-float-le Function
Signature

byte-vector-to-float-le (bv) => (res)

Parameters

  • bv – An instance of <stretchy-byte-vector-subsequence>.

Values

  • res – An instance of <float>.

float-to-byte-vector-be Function
Signature

float-to-byte-vector-be (float) => (res)

Parameters

  • float – An instance of <float>.

Values

  • res – An instance of <byte-vector>.

float-to-byte-vector-le Function
Signature

float-to-byte-vector-le (float) => (res)

Parameters

  • float – An instance of <float>.

Values

  • res – An instance of <byte-vector>.

Stretchy Vector Subsequences

The underlying byte vector which is used in binary data is a <stretchy-byte-vector>. To allow zerocopy while parsing, and providing each frame parser only with a byte vector of the required size for the type, there is a <stretchy-vector-subsequence> which tracks the byte-vector together with a start and end index.

Note

Should live in a separate module and types can be narrowed a bit further.

<stretchy-byte-vector> Constant
Type

<type>

Value

limited(<stretchy-vector>, of: <byte>)

<stretchy-vector-subsequence> Abstract Class
Superclasses

<vector>

Init-Keywords

  • data –

  • end –

  • start –

subsequence Generic function
Signature

subsequence (seq) => (#rest results)

Parameters

  • seq – An instance of <object>.

Values

  • #rest results – An instance of <object>.

<stretchy-byte-vector-subsequence> Class
Superclasses

<stretchy-vector-subsequence>

decode-integer Generic function
Signature

decode-integer (seq count) => (#rest results)

Parameters

  • seq – An instance of <object>.

  • count – An instance of <object>.

Values

  • #rest results – An instance of <object>.

encode-integer Generic function
Signature

encode-integer (value seq count) => (#rest results)

Parameters

  • value – An instance of <object>.

  • seq – An instance of <object>.

  • count – An instance of <object>.

Values

  • #rest results – An instance of <object>.