rudp

Go-rudp - Reliable UDP

Go-rudp is a reliable udp implementation for use in multiplayer games written in golang.

Features

Send reliable and unreliable udp packets. Client and server provide verification of received reliable packets.

How does it work?

Packet [reliable][sequence][remote_ack][remote_bitfield][payload]

Go-rupd adds additional packet information to all outgoing packets.

• reliable[uint8]: 0 or 1 - if set to 1 the packet is reliable.
• seqeunce[uint32]: an incremental sequence number is assigned to each reliable packet.
• remote_ack[uint32]: The last reliable packet received from the remote source.
• remote_bitfield[uint32]: A bitfield used to acknowledge the receiption of up to the past 32 packets from the remote source. 1=received, 0=not received.
• payload: the data the user is sending.

When a reliable packet is received, the remote_ack is updated with the sequence number if newer than the current value (sometimes udp receives out of order so it may be an older sequence number). Then the remote_bitfield is updated using some bit shifting and bit setting. Then only the payload data is passed through.

How to use the library

Server.go

server, _ := rudp.Listen("udp4", "127.0.0.1", 8000)
defer server.Close()

// receiving a packet
// n is the length of the received packet (payload only)
// verified is a list of reliable packets that the client has received since the last read
temp := make([]byte, 1024)
n, verified, client_addr, err = server.ReadFromUDP(temp)

// sending a packet
// The third argument in WriteToUDP is whether the packet should be reliable 
// The second return value is the sequence number used for this packet
payload := []byte{1} // payload to send
n, sent_seq_number, err := server.WriteToUDP(&payload, *client_addr, true) 

// When sending and receiving packets, you are responsible for keeping a list of sent packet sequence numbers and removing verified sequences from the list.  See an example implementation in the examples folder.

Client.go

client, _ := Dial("udp4", "127.0.0.1", 8000)
defer client.Close()

// receiving a packet
// n is the length of the received packet (payload only)
// verified is a list of reliable packets that the remote has received since the last read
temp := make([]byte, 1024)
n, verified, server_addr, err = client.ReadFromUDP(temp)

// sending a packet
// The third argument in WriteToUDP is whether the packet should be reliable 
// The second return value is the sequence number used for this packet
payload := []byte{1} // payload to send
n, sent_seq_number, err := client.Write(&payload, true) 

// When sending and receiving packets, you are responsible for keeping a list of sent packet sequence numbers and removing verified sequences from the list.  See an example implementation in the examples folder.