mini_udp 0.3.0

A minimal implementation of a reliability protocol on top of UDP for game networking
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use std::net::{SocketAddr, ToSocketAddrs, UdpSocket};

use crate::prelude::*;

pub trait CommunicatorSocket {
    fn bind<A: ToSocketAddrs>(addr: A) -> Self;
    /// Set the interval at which reliable unordered packets are to be resend if no
    /// acknowledgement has been received.
    ///
    /// The default is 100 milliseconds.
    fn with_reliable_unordered_resend_interval(self, interval: Duration) -> Self;
    /// Set the interval at which reliable ordered packets are to be resend if no
    /// acknowledgement has been received.
    ///
    /// The default is 100 milliseconds.
    fn with_reliable_ordered_resend_interval(self, interval: Duration) -> Self;
}

pub(crate) trait SocketSendAddr {
    fn send(
        &self,
        socket: &mut UdpCommunicatorSocket,
        slice_index: impl std::slice::SliceIndex<[u8], Output = [u8]>,
    ) -> Result<usize, std::io::Error>;
}

pub(crate) struct UdpCommunicatorSocket {
    pub socket: UdpSocket,
    pub data_buffer: [u8; MAX_PACKET_LEN],
    pub reliable_unordered_resend_interval: Duration,
    pub reliable_ordered_resend_interval: Duration,
    #[cfg(feature = "debug")]
    pub drop_probability: Option<f64>,
    #[cfg(feature = "debug")]
    pub corruption_probability: Option<f64>,
    #[cfg(feature = "debug")]
    pub fake_delay: std::ops::Range<u64>,
    #[cfg(feature = "debug")]
    pub debug_logs: bool,
    #[cfg(feature = "debug")]
    /// For each read from the socket, this stores the address from which the data was received,
    /// the copied data_buffer, the amount of bytes read and the instant at to which this packet
    /// is being delayed.
    pub fake_delayed_buffer: Vec<(
        Option<SocketAddr>,
        [u8; MAX_PACKET_LEN],
        usize,
        std::time::Instant,
    )>,
}

impl CommunicatorSocket for UdpCommunicatorSocket {
    fn bind<A: ToSocketAddrs>(addr: A) -> Self {
        let socket = UdpSocket::bind(addr).expect("Failed to bind to udp socket");
        socket
            .set_nonblocking(true)
            .expect("Failed to set udp socket to nonblocking mode");
        Self {
            socket,
            data_buffer: [0; MAX_PACKET_LEN],
            reliable_unordered_resend_interval: Duration::from_millis(100),
            reliable_ordered_resend_interval: Duration::from_millis(100),
            #[cfg(feature = "debug")]
            drop_probability: None,
            #[cfg(feature = "debug")]
            corruption_probability: None,
            #[cfg(feature = "debug")]
            fake_delay: 0..0,
            #[cfg(feature = "debug")]
            debug_logs: false,
            #[cfg(feature = "debug")]
            fake_delayed_buffer: vec![],
        }
    }

    fn with_reliable_unordered_resend_interval(mut self, interval: Duration) -> Self {
        self.reliable_ordered_resend_interval = interval;
        self
    }

    fn with_reliable_ordered_resend_interval(mut self, interval: Duration) -> Self {
        self.reliable_ordered_resend_interval = interval;
        self
    }
}

impl SocketSendAddr for () {
    fn send(
        &self,
        socket: &mut UdpCommunicatorSocket,
        slice_index: impl std::slice::SliceIndex<[u8], Output = [u8]>,
    ) -> Result<usize, std::io::Error> {
        socket.socket.send(&socket.data_buffer[slice_index])
    }
}

impl SocketSendAddr for SocketAddr {
    fn send(
        &self,
        socket: &mut UdpCommunicatorSocket,
        slice_index: impl std::slice::SliceIndex<[u8], Output = [u8]>,
    ) -> Result<usize, std::io::Error> {
        socket
            .socket
            .send_to(&socket.data_buffer[slice_index], self)
    }
}