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use std::net::{IpAddr, SocketAddr};

/// Explicit congestion notification codepoint
#[repr(u8)]
#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
pub enum EcnCodepoint {
    #[doc(hidden)]
    Ect0 = 0b10,
    #[doc(hidden)]
    Ect1 = 0b01,
    #[doc(hidden)]
    Ce = 0b11,
}

impl EcnCodepoint {
    /// Create new object from the given bits
    pub fn from_bits(x: u8) -> Option<Self> {
        use self::EcnCodepoint::*;
        Some(match x & 0b11 {
            0b10 => Ect0,
            0b01 => Ect1,
            0b11 => Ce,
            _ => {
                return None;
            }
        })
    }
}

#[derive(Debug)]
pub struct Transmit {
    /// The socket this datagram should be sent to
    pub destination: SocketAddr,
    /// Explicit congestion notification bits to set on the packet
    pub ecn: Option<EcnCodepoint>,
    /// Contents of the datagram
    pub contents: Vec<u8>,
    /// The segment size if this transmission contains multiple datagrams.
    /// This is `None` if the transmit only contains a single datagram
    pub segment_size: Option<usize>,
    /// Optional source IP address for the datagram
    pub src_ip: Option<IpAddr>,
}