List of Data Types

The server support a wide range of data types, both in unlang and in the dictionaries. This page outlines the names and functionality of those data types.

Basic Data Types

There are a number of "basic" data types. These data types are fixed-size, and encapsulate simple concepts such as "integer" or "IP address".

Basic data types can be used in unlang, as they contain simple values which can be compared, or assigned to one attribute. In most cases, it is not necessary to know the name of the data type. It is possible to write values in the format you expect, The server will do "the right thing" when interpreting the values.

Table 1. Basic Data Types
Data Type	Description
bool	boolean
date	calendar date
ethernet	Ethernet address
float32	32-bit floating point number
float64	64-bit floating point number
ifid	interface ID
int8	8-bit signed integer
int16	16-bit signed integer
int32	32-bit signed integer
int64	64-bit signed integer
ipaddr	IPv4 address
ipv6addr	IPv6 address
ipv4prefix	IPv4 network with address and prefix length
ipv6prefix	IPv6 network with address and prefix length
octets	raw binary, printed as hex strings
string	printable strings
time_delta	difference between two calendar dates
uint8	8-bit unsigned integer
uint16	16-bit unsigned integer
uint32	32-bit unsigned integer
uint64	64-bit unsigned integer

Structural Data Types

The following data types are "structural", in that they form parent-child relationships between attributes. These data types can only be used in the dictionaries. They cannot be used in unlang statements.

Table 2. Structural Data Types
Data Type	Description
group	generic grouping
struct	structure which contains fixed-width fields
tlv	type-length-value which contains other attributes
vendor	Encapsulation of a vendor within data type `vsa`
vsa	Encapsulation of vendor-specific attributes

Each structural data type serves a different purpose. Each structural data type can contain child attributes. The different structural types have different behaviors about what kind of children they can contain, and how the data type is sent in a packet over the network.

struct: A struct contains fixed-sized data types, in a pre-defined order.

The struct can only contain a fixed and pre-defined list of child attributes. These attributes are the fields, or members, of the structure.

The struct always encodes all of its children. If a child is missing, then the relevant field is filled with zeros.

group: A group contains an arbitrary collection of children, in any order.

+ The group can contain any child attributes, so long as they are within the same protocol namespace. See the dictionary/attribute.adoc[ATTRIBUTE] documentation for more information.

+ The group only encodes the child attributes which have been created and stored within the group. The order of children does not matter.

tlv: A tlv is a group which has a limited subset of children.

The tlv can only contain child attributes which have been defined as children of the tlv.

The tlv only encodes the child attributes which have been created and stored within the tlv. The order of children does not matter.
vendor: A vendor is a group which has a limited subset of children: attributes which have been defined by that vendor.

The vendor can only contain child attributes which have been defined by the vendor.

The vendor only encodes the child attributes which have been created and stored within the vendor. The order of children does not matter. In practice, the vendor attributes are usually encoded with a 32-bit vendor ID, which identies the vendor.

A vendor data type can only be a child of a vsa data type.
vsa: A vsa is a group which has a limited subset of children: `vendor`s.

The vsa can only contain child attributes which are `vendor`s

The vsa only encodes the vendor attributes which have been created and stored within the vsa. The order of children does not matter.

A vsa data type can only be a contain children of the vendor data type.