multiprotocol: multiformat inspired self-describing protocol identifiers

⚠️ THIS IS STILL AN EARLY DRAFT ⚠️

In this specification we describe a simple method for nodes to advertise their capabilities. The protocol is heavily inspired by multiformats and provides both a human and machine readable representation.

The goal is to provide node identification beyond the multiaddr connection info which can be appended to the end of the address.

This repository contains the multiprotocol definition used by vac, the go implementation however is generic and therefore anyone can implement their own table.

The table is represented using the following CSV format:

code, size, name, comment
1,    0,    vac,  namespace
2,    V,    waku,

field	description
code	This field contains the code identifying the key.
size	This field identifies the expected keys size, it can be any number or V, indicating that the value itself is length prefixed.
name	The human readable name of the field.
comment	Any developer related comments for the field.

Namespaces should be generic to not cause overlap, vac uses 42

Human-readable:

/<namespace>/<protocol>/<version>(/<capability>/<version>|<capability>)+

Examples:

/vac/waku/2
/vac/waku/2/relay/2
/vac/waku/2/store/1

Machine-readable:

<namespace uvarint><protocol uvarint><version uvarint>(<protoCode uvarint><value []byte>)+

Examples:

0x2a 0x2 0x1 0x32 # /vac/waku/2
0x2a 0x2 0x1 0x32 0x4 0x1 0x32 # /vac/waku/2/relay/2
0x2a 0x2 0x1 0x32 0x3 0x1 0x32 # /vac/waku/2/store/1

With multiaddr:

/ip4/127.0.0.1/tcp/9000/vac/waku/0.2/relay/0.2