Crate dpmaster_proto

dpmaster protocol

dpmaster

dpmaster, “an open master server”, is both a generic protocol to register game servers with a master server and query them from game clients as well as a reference master server implementation written in the C programming language.

This crate implements the dpmaster wire protocol as defined in its “Technical information” documentation.

dpmaster protocol

The dpmaster protocol is a custom UDP protocol where datagram packets contain a mix of binary delimiters as well as ASCII text.
Neither the protocol nor its specification are versioned, but they have not changed for a couple of years.

This crate implements (de)serialization of (not-yet all) packets, which the spec calls messages:

• heartbeat message
• getinfo message
• infoResponse message
• getservers message
• getserversResponse message
• getserversExt message
• getserversExtResponse message

Message flows

The “master server” concept is that there is a central server instance, e.g. at master.example:27950, that all game servers report to.
Game servers then register themselves with the master server, e.g. their IPs 192.0.2.1:27960 / [2001:db8::1]:27964 aswell as some Info metadata.
Game clients query the master server for a (filtered) list of game servers.

heartbeat message flow

The “heartbeat” message flow registers a game server with the master server.
It should be initiated by game servers when their configuration changes and periodically to remain registered with the master server.

❶ Game server sends heartbeat message to master server

❷ Master server sends getinfo message with new challenge back to game server

❸ Game server sends infoResponse message with same challenge back to master server

getservers message flow

The “getservers” message flow queries a master server for game servers.
It is initiated by game clients e.g. when they want to display a list of servers in their UI so players can decide which one to connect to.

❶ Game client sends getservers message to master server

❷ Master server sends getserversResponse message(s) back to game client

dpmaster-proto crate

This crate implements the dpmaster protocol wire format, i.e. it allows to serialize and deserialize protocol messages as bytes to and from UDP packets.
It does however not contain logic (“sans I/O”), e.g. to implement a master server, game server or game client.

The dpmaster-codec crate implements Tokio codecs on top of this protocol crate.
The dpmaster-game-client-bin crate implements a “game client” on top of a codec in form of a command-line-interface to query a master server for game servers.

Re-exports

• pub use messages::Challenge;
• pub use messages::GameName;
• pub use messages::GameType;
• pub use messages::GetInfoMessage;
• pub use messages::GetServersExtResponseMessage;
• pub use messages::GetServersResponseMessage;
• pub use messages::HeartbeatMessage;
• pub use messages::Info;
• pub use messages::InfoKey;
• pub use messages::InfoResponseMessage;
• pub use messages::InfoValue;
• pub use messages::ProtocolName;
• pub use crate::error::ProtocolError;

Modules

• deserializer
  deserializer for messages
• error
  crate error types
• messages
  Protocol datagram “messages” and related types
• serializer
  serializer for messages

Type Definitions

• Result
  std::result::Result alias with ProtocolError as Err