// Copyright 2018 Amazon.com, Inc. or its affiliates. All Rights Reserved.
// SPDX-License-Identifier: Apache-2.0
//

/// This module implements the Unix Domain Sockets backend for vsock - a mediator between
/// guest-side AF_VSOCK sockets and host-side AF_UNIX sockets. The heavy lifting is performed by
/// `muxer::VsockMuxer`, a connection multiplexer that uses `super::csm::VsockConnection` for
/// handling vsock connection states.
/// Check out `muxer.rs` for a more detailed explanation of the inner workings of this backend.
///
mod muxer;
mod muxer_killq;
mod muxer_rxq;

pub use muxer::VsockMuxer as VsockUnixBackend;
pub use Error as VsockUnixError;

mod defs {
    /// Maximum number of established connections that we can handle.
    pub const MAX_CONNECTIONS: usize = 1023;

    /// Size of the muxer RX packet queue.
    pub const MUXER_RXQ_SIZE: usize = 256;

    /// Size of the muxer connection kill queue.
    pub const MUXER_KILLQ_SIZE: usize = 128;
}

#[derive(Debug)]
pub enum Error {
    /// Error registering a new epoll-listening FD.
    EpollAdd(std::io::Error),
    /// Error creating an epoll FD.
    EpollFdCreate(std::io::Error),
    /// The host made an invalid vsock port connection request.
    InvalidPortRequest,
    /// Error accepting a new connection from the host-side Unix socket.
    UnixAccept(std::io::Error),
    /// Error binding to the host-side Unix socket.
    UnixBind(std::io::Error),
    /// Error connecting to a host-side Unix socket.
    UnixConnect(std::io::Error),
    /// Error reading from host-side Unix socket.
    UnixRead(std::io::Error),
    /// Muxer connection limit reached.
    TooManyConnections,
}

type Result<T> = std::result::Result<T, Error>;
type MuxerConnection = super::csm::VsockConnection<std::os::unix::net::UnixStream>;