protocol

Documentation

Easy protocol definitions in Rust.

This crate adds a custom derive that can be added to types, allowing structured data to be sent and received from any IO stream.

Networking is built-in, with special support for TCP and UDP.

The protocol you define can be used outside of networking too - see the Parcel::from_raw_bytes and Parcel::raw_bytes methods.

This crate also provides:

• TCP and UDP modules for easy sending and receiving of Parcels
• A generic middleware library for automatic transformation of sent/received data
  • Middleware has already been written to support compression
  • Custom middleware can be implemented via a trait with two methods

Checkout the examples folder for usage.

Usage

Add this to your Cargo.toml:

[dependencies]
protocol = { version = "3.4", features = ["derive"] }

And then define a type with the #[derive(protocol::Protocol)] attribute:

#[derive(protocol::Protocol)]structHello{puba:String,pubb:u32,}

Under the hood

The most interesting part here is the protocol::Parcel trait. Any type that implements this trait can then be serialized to and from a byte stream. All primitive types, standard collections, tuples, and arrays implement this trait.

This crate becomes particularly useful when you define your own Parcel types. You can use #[derive(protocol::Protocol)] to do this. Note that in order for a type to implement Parcel, it must also implement Clone, Debug, and PartialEq.

#[derive(Parcel,Clone,Debug,PartialEq)]pubstructHealth(f32);#[derive(Parcel,Clone,Debug,PartialEq)]pubstructSetPlayerPosition{pubposition:(f32,f32),pubhealth:Health,pubvalues:Vec<String>,}

Custom derive

Any user-defined type can have the Parcel trait automatically derived.

Example

#[derive(protocol::Protocol,Clone,Debug,PartialEq)]pubstructHandshake;#[derive(protocol::Protocol,Clone,Debug,PartialEq)]pubstructHello{id:i64,data:Vec<u8>,}#[derive(protocol::Protocol,Clone,Debug,PartialEq)]pubstructGoodbye{id:i64,reason:String,}#[derive(protocol::Protocol,Clone,Debug,PartialEq)]pubstructNode{name:String,enabled:bool}#[protocol(discriminant = "integer")]#[derive(protocol::Protocol,Clone,Debug,PartialEq)]pubenumPacketKind{#[protocol(discriminator(0x00))]Handshake(Handshake),#[protocol(discriminator(0xaa))]Hello(Hello),#[protocol(discriminator(0xaf))]Goodbye(Goodbye),}fnmain(){use std::net::TcpStream;let stream = TcpStream::connect("127.0.0.1:34254").unwrap();letmut connection = protocol::wire::stream::Connection::new(stream, protocol::wire::middleware::pipeline::default());
connection.send_packet(&Packet::Handshake(Handshake)).unwrap();
connection.send_packet(&Packet::Hello(Hello{id:0,data:vec![55]})).unwrap();
connection.send_packet(&Packet::Goodbye(Goodbye{id:0,reason:"leaving".to_string()})).unwrap();loop{ifletSome(response) = connection.receive_packet().unwrap(){println!("{:?}", response);break;}}}

Enums

Discriminators

Enum values can be transmitted either by their 1-based variant index, or by transmitting the string name of each variant.

NOTE: The default behaviour is to use the variant name as a string (string).

This behaviour can be changed by the #[protocol(discriminant = "<type>")] attribute.

Supported discriminant types:

• string (default)
  • This transmits the enum variant name as the over-the-wire discriminant
  • This uses more bytes per message, but it very flexible
• integer
  • This transmits the 1-based variant number as the over-the-wire discriminant
  • If enum variants have explicit discriminators, the
  • Enum variants cannot be reordered in the source without breaking the protocol

#[derive(protocol::Protocol,Clone,Debug,PartialEq)]#[protocol(discriminant = "string")]pubenumPlayerState{Stationary,Flying{velocity:(f32,f32,f32)},// Discriminators can be explicitly specified.#[protocol(discriminator("ArbitraryOverTheWireName"))]Jumping{height:f32},}

Misc

You can rename the variant for their serialisation.

#[derive(protocol::Protocol,Clone,Debug,PartialEq)]#[protocol(discriminant = "string")]pubenumFoo{Bar,#[protocol(name = "Biz")]// the Bing variant will be send/received as 'Biz'.Bing,Baz,}