GrabbaBER_TLV Class Reference

Description

Encapsulation of Basic Encoding Rule: Type, Length, Value (BER-TLV) data structures.

This class implements a BER-TLV structure as per the X.690 standard.

Note that this structure is nested - a BER-TLV object may encode a collection of other BER-TLV structures, or it may encode primitive data.

Additional information may be found at:

• https://en.wikipedia.org/wiki/X.690#BER_encoding
• https://en.wikipedia.org/wiki/Type-length-value

Invariant

Always contains a valid type structure, a valid length structure, and a value field consistent with the type and length.

Note

All property values are passed by copy; a new copy of the value will be generated each time a property is read.

Thread safety:

• The current version of this class is immutable, and thus fully thread-safe
• Future updates to this class will guarantee safety only to the following level:
  • Concurrent accesses to distinct hierarchies: safe
  • Concurrent accesses to distinct objects within same hierarchy: safe, providing no objects are added to or removed from the hierarchy
  • Concurrent accesses to the same object: unsafe, unless all accesses are read-only (property reads, get (GrabbaBER_TLV), getPrimitive (GrabbaBER_TLV), getConstructed (GrabbaBER_TLV))

See also

GrabbaMRTD_API, which provides API functions that utilise this class.

Inheritance diagram for GrabbaBER_TLV:

Instance Methods
(NSData *_Nonnull)	- get
	Extract the data, in raw BER-TLV binary format. More...
(NSArray< GrabbaBER_TLV * > *_Nonnull)	- getConstructed
	Copy the constructed data, if any; for primitive BER-TLV objects, this property holds an empty collection. More...
(NSData *_Nonnull)	- getPrimitive
	Copy the primitive data, if any; for constructed BER-TLV objects, this property holds an empty NSData object. More...
(instancetype _Nullable)	- init
	Not callable (NS_UNAVAILABLE) - this capability will be added in a future release. More...

Properties
BOOL	constructed
	Is the stored value constructed of other BER-TLV objects? More...
uint64_t	constructedSize
	Count of nested BER-TLV structures in the constructed data, if any; for primitive BER-TLV objects, this will be zero. More...
BOOL	definiteLength
	Is the stored length for this structure definite? More...
GrabbaBER_ID_Class	idClass
	Type field's ID class. More...
uint64_t	length
	Stored length for this structure (in bytes); if the stored length is indefinite then this will be zero. More...
BOOL	primitive
	Is the stored value primitive? More...
uint64_t	primitiveSize
	Size in bytes of the primitive data; for constructed BER-TLV objects, this will be zero. More...
uint64_t	size
	Overall size (in bytes) of the structure - i.e. the length of the data returned by get. More...
uint64_t	tag
	Type field's ID tag. More...

Method Documentation

get()

- (NSData* _Nonnull) get

Extract the data, in raw BER-TLV binary format.

Returns

Raw representation of the entire structure

getConstructed()

- (NSArray<GrabbaBER_TLV*>* _Nonnull) getConstructed

Copy the constructed data, if any; for primitive BER-TLV objects, this property holds an empty collection.

getPrimitive()

- (NSData* _Nonnull) getPrimitive

Copy the primitive data, if any; for constructed BER-TLV objects, this property holds an empty NSData object.

init()

- (instancetype _Nullable) init

Not callable (NS_UNAVAILABLE) - this capability will be added in a future release.

Property Documentation

constructed

- (BOOL) constructed

readnonatomicassign

Is the stored value constructed of other BER-TLV objects?

NO if the stored data is primitive; YES if it is constructed of other BER-TLV objects. Opposite of primitive.

constructedSize

- (uint64_t) constructedSize

readnonatomicassign

Count of nested BER-TLV structures in the constructed data, if any; for primitive BER-TLV objects, this will be zero.

Note

Only directly nested BER-TLV structures are counted; their descendants (if any) are excepted.

definiteLength

- (BOOL) definiteLength

readnonatomicassign

Is the stored length for this structure definite?

YES if the length is definite (known), NO if it is indefinite (unknown)

idClass

- (GrabbaBER_ID_Class) idClass

readnonatomicassign

Type field's ID class.

length

- (uint64_t) length

readnonatomicassign

Stored length for this structure (in bytes); if the stored length is indefinite then this will be zero.

See also

Property size for the full size of the TLV structure, including type and length fields

primitive

- (BOOL) primitive

readnonatomicassign

Is the stored value primitive?

YES if the stored data is primitive; NO if it is constructed of other BER-TLV objects. Opposite of constructed.

primitiveSize

- (uint64_t) primitiveSize

readnonatomicassign

Size in bytes of the primitive data; for constructed BER-TLV objects, this will be zero.

size

- (uint64_t) size

readnonatomicassign

Overall size (in bytes) of the structure - i.e. the length of the data returned by get.

tag

- (uint64_t) tag

readnonatomicassign

Type field's ID tag.