clan-sidebus/sidebus-broker/src/main.rs

mod bus;
mod portal;
mod vsock;

use bus::SharedHostedBus;
use clap::Parser;
use std::{path::PathBuf, sync::Arc};
use tokio::{net::UnixListener, process::Command, sync::Mutex};
use tracing::error;
use zbus::names::WellKnownName;

// https://github.com/rust-lang/rfcs/issues/2407#issuecomment-385291238
macro_rules! enclose {
    ( ($( $x:ident ),*) $y:expr ) => {
        {
            $(let $x = $x.clone();)*
            $y
        }
    };
}

#[derive(Parser)]
#[command(version, about, long_about = None)]
struct BrokerCli {
    /// Create unix socket listeners for all internal busses in the provided directory
    #[clap(long)]
    debug_access: Option<PathBuf>,

    /// Private XDG_RUNTIME_DIR for the VM ('./doc' under it will be used as the document portal FS mountpoint, './fs.sock' will be the FS)
    #[clap(long)]
    runtime_dir: PathBuf,

    /// Absolute path where the './doc' under the runtime-dir would be mounted over virtiofs in the guest
    #[clap(long, default_value = "/run/vm-doc-portal")]
    guest_mountpoint: PathBuf,

    /// Vsock port number to listen on
    #[clap(long)]
    vsock_port: u32,
}

async fn new_hosted_bus() -> eyre::Result<(
    Arc<Mutex<bus::HostedBus>>,
    zbus::OwnedGuid,
    bus::NameOwnerStream,
)> {
    let mut bus = bus::HostedBus::new().await?;
    let guid = bus.server_guid().to_owned().into();
    let owner_stream = bus.name_owner_changes().await?;

    Ok((Arc::new(Mutex::new(bus)), guid, owner_stream))
}

#[tokio::main]
async fn main() -> eyre::Result<()> {
    tracing_subscriber::fmt::init();

    let cli = BrokerCli::parse();

    let (vm_bus, vm_bus_guid, _) = new_hosted_bus().await?;
    let (priv_bus, _, mut priv_lst) = new_hosted_bus().await?;

    if let Some(dir_path) = cli.debug_access {
        if !dir_path.is_dir() {
            error!(path = %dir_path.display(), "--debug-access path is not an existing directory");
            std::process::exit(1);
        }
        let vm_dbg_listener = UnixListener::bind(dir_path.join("vm.sock"))?;
        let _vm_dbg_task = tokio::spawn(vm_bus.clone().run_unix_listener(vm_dbg_listener));
        let priv_dbg_listener = UnixListener::bind(dir_path.join("priv.sock"))?;
        let _priv_dbg_task = tokio::spawn(priv_bus.clone().run_unix_listener(priv_dbg_listener));
        // TODO: unlink sockets on exit
    }

    std::fs::create_dir_all(&cli.runtime_dir)?;

    let _xps = priv_bus
        .clone()
        .spawn_external_client(
            Command::new(env!("BIN_XDG_PERMISSION_STORE"))
                .env("XDG_RUNTIME_DIR", cli.runtime_dir.as_os_str())
                .kill_on_drop(true),
        )
        .await?;

    let impl_permission_store =
        WellKnownName::from_static_str("org.freedesktop.impl.portal.PermissionStore")?.into();
    priv_lst.wait_for_acquisition(impl_permission_store).await?;

    let _xdp = priv_bus
        .clone()
        .spawn_external_client(
            Command::new(env!("BIN_XDG_DOCUMENT_PORTAL"))
                .env("XDG_RUNTIME_DIR", cli.runtime_dir.as_os_str())
                .kill_on_drop(true),
        )
        .await?;

    let portal_documents =
        WellKnownName::from_static_str("org.freedesktop.portal.Documents")?.into();
    priv_lst.wait_for_acquisition(portal_documents).await?;

    let _vfs = Command::new(env!("BIN_VIRTIOFSD"))
        .args(&[
            "--shared-dir",
            cli.runtime_dir.join("doc").to_str().unwrap(),
            "--socket-path",
            cli.runtime_dir.join("fs.sock").to_str().unwrap(),
            "--uid-map",
            ":1000:1001:1:",
            "--gid-map",
            ":100:100:1:",
            "--log-level",
            "debug",
        ])
        .env("XDG_RUNTIME_DIR", cli.runtime_dir.as_os_str())
        .kill_on_drop(true)
        .spawn();
    // TODO: die when it exits

    let vm_bus_conn = vm_bus.lock().await.connect_channel(false).await?;
    let priv_bus_conn = priv_bus.lock().await.connect_channel(false).await?;
    let host_session_conn = zbus::connection::Builder::session()?.build().await?;
    let file_chooser_imp = portal::file_chooser::FileChooser::new(
        &host_session_conn,
        &priv_bus_conn,
        cli.guest_mountpoint,
    )
    .await?;
    vm_bus_conn
        .request_name("org.freedesktop.portal.Desktop")
        .await?;
    let true = vm_bus_conn
        .object_server()
        .at("/org/freedesktop/portal/desktop", file_chooser_imp)
        .await?
    else {
        unreachable!("our own fresh bus can't have interfaces already provided");
    };

    // TODO: modprobe vhost_vsock first!
    // NOTE: Every individual D-Bus client inside of the VM is a new client here!
    vsock::ListenerBuilder::new(vsock::VsockAddr::new(
        vsock::VMADDR_CID_HOST,
        cli.vsock_port,
    ))
    .with_label("VM Bus")
    .listen(move |client| {
        enclose! { (vm_bus, vm_bus_guid) async move {
            // TODO: Not necessary to go through the channel, add vsock support to the Peer too
            let client_conn = client.build((&vm_bus_guid).into()).await?;
            let vmbus_conn = vm_bus.lock().await.connect_channel(true).await?;
            sidebus_common::raw::splice_conns(client_conn, vmbus_conn).await;
            Ok(())
        } }
    })
    .await?;

    Ok(())
}