tokio-multicast 0.7.2

use std::net::IpAddr;
use std::os::fd::AsRawFd;

use socket2::Socket;

use crate::{raw, Interface, Membership, MulticastError, Result};

pub(crate) fn set_reuse_port(socket: &Socket, enabled: bool) -> Result<()> {
    let value: libc::c_int = enabled.into();
    let result = unsafe {
        libc::setsockopt(
            socket.as_raw_fd(),
            libc::SOL_SOCKET,
            libc::SO_REUSEPORT,
            (&value as *const libc::c_int).cast(),
            std::mem::size_of_val(&value) as libc::socklen_t,
        )
    };
    if result == -1 {
        return Err(std::io::Error::last_os_error().into());
    }
    Ok(())
}

pub(crate) fn join_membership(
    socket: &Socket,
    membership: &Membership,
    inbound_interface: Option<&Interface>,
) -> Result<()> {
    match membership {
        Membership::AnySource {
            group: IpAddr::V4(group),
        } => {
            let interface = raw::default_interface_v4(inbound_interface)?;
            raw::membership_target(membership)?;
            socket.join_multicast_v4(group, &interface)?;
            Ok(())
        }
        Membership::AnySource {
            group: IpAddr::V6(group),
        } => {
            let index = raw::default_interface_v6(inbound_interface)?;
            raw::membership_target(membership)?;
            socket.join_multicast_v6(group, index)?;
            Ok(())
        }
        Membership::SourceSpecific { .. } => Err(MulticastError::UnsupportedOption(
            "source-specific multicast",
        )),
    }
}

pub(crate) fn loopback_interface_v6() -> Option<u32> {
    let name = std::ffi::CString::new("lo").ok()?;
    let index = unsafe { libc::if_nametoindex(name.as_ptr()) };
    (index != 0).then_some(index)
}