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The STRUCT keyword

Syntax
STRUCT <name> <field> <value> [<flags>]
Description

The STRUCT keyword defines a child structure of a previous struct, which is keyed by a particular MEMBER.

Many protocols are defined as a header which contains information about the protocol, and a data portion which contains data carried by that header. The header usually includes a type field, which defines how the data portion is interpreted. The STRUCT keyword allows the server to automatically decode these protocols, and all of their contents.

<name>

The name of the attribute. The name can contain alphanumeric characters, -, and _. The name should be short and descriptive.

As the names are hierarchical, the name is scoped to its parent. So the name Counter can mean different things, depending on its context.

<field>

The name of a previous MEMBER which has been marked up with the word key in the flags field.

In most cases, the <field> reference is simply the name of a field in the attribute of type struct which was defined immediately before this definition.

The <field> reference can also be an OID-style name, as in Client-Id.Type. The name is always looked up in the current dictionary. References cannot be to fields in other dictionaries.

<value>

When the <field> has this value, the data is interpreted as this struct. Numbers can be specified as decimal (19), or as hex (0xffee).

<flags>

Can only be length=uint8 or length=uint16. When encoding or decoding the structure, it is prefixed by a uint8 or uint16 field containing the length of the structure.

Common flags and meanings

Name Description

length=uint8

When encoding or decoding the structure, it is prefixed by a uint8 field containing the length of the structure.

length=uint16

When encoding or decoding the structure, it is prefixed by a uint16 field containing the length of the structure.
Examples
ATTRIBUTE Information 1 struct
MEMBER Type uint8 key

STRUCT Foo Type 1
MEMBER Bar uint16
MEMBER Baz uint16