Network Encodings

Encodings

Messages

The communication between nodes is wrapped in Messages.

The maximum size of a message is 10 MiB (10 * 2^20 bytes).

A message is serialized as follows:

Type	Name	Description
uint32_t	magic	Magic Number: Always 0x42042042
var_uint	type	Message Type number (ID of message)
uint32_t	length	Length of the message content
uint32_t	checksum	CRC32 checksum of the message content
binary	body	Message content

Currently, there are 33 different types of messages in use.

The serialized message is then split in chunks and sent using the encoding defined in DataChannel.js.

DataChannel

Before messages are sent out to the network, they are split in chunks not more than 16 KiB (16 * 2^10 bytes) long.

A chunk is encoded as follows:

Type	Name	Description
uint8_t	tag	Chunk counter. Begins at 0 and is incremented with each chunk. After 255 it resets back to 0.
binary	chunk	Chunk content.

Connections

Chunks are currently transmitted over two types of connections.

WebSockets

• Needs a publicly addressable node that listens for incoming connections.
• Other nodes connect to the server to establish a WebSocket channel.
• There are two types of WebSocket connections
  • ws://: Unencrypted communication over TCP.
  • wss://: Encrypted communication over TLS. The server requires a valid HTTPS certificate for this mode.

WebRTC

• Creates direct connections between two nodes that are not publicly addressable/peers behind NAT. (e.g. Browsers in WiFi)
• Needs publicly addressable signaling servers for negotiating connections between two nodes.