zbus 6.2.0

mod auth_mechanism;
mod client;
mod command;
mod common;
#[cfg(feature = "p2p")]
mod server;

use async_trait::async_trait;
#[cfg(unix)]
use rustix::process::geteuid;
use std::fmt::Debug;

#[cfg(windows)]
use crate::win32;
use crate::{Error, OwnedGuid, Result, names::OwnedUniqueName};

use super::socket::{BoxedSplit, ReadHalf, WriteHalf};

pub use auth_mechanism::AuthMechanism;
use client::Client;
use command::Command;
use common::Common;
#[cfg(feature = "p2p")]
use server::Server;

/// The result of a finalized handshake
///
/// The result of a finalized [`ClientHandshake`] or [`ServerHandshake`].
///
/// [`ClientHandshake`]: struct.ClientHandshake.html
/// [`ServerHandshake`]: struct.ServerHandshake.html
#[derive(Debug)]
pub struct Authenticated {
    pub(crate) socket_write: Box<dyn WriteHalf>,
    /// The server Guid
    pub(crate) server_guid: OwnedGuid,
    /// Whether file descriptor passing has been accepted by both sides
    #[cfg(unix)]
    pub(crate) cap_unix_fd: bool,

    pub(crate) socket_read: Option<Box<dyn ReadHalf>>,
    pub(crate) already_received_bytes: Vec<u8>,
    #[cfg(unix)]
    pub(crate) already_received_fds: Vec<std::os::fd::OwnedFd>,
    pub(crate) unique_name: Option<OwnedUniqueName>,
}

impl Authenticated {
    /// Create a client-side `Authenticated` for the given `socket`.
    pub async fn client(
        socket: BoxedSplit,
        server_guid: Option<OwnedGuid>,
        mechanism: Option<AuthMechanism>,
        bus: bool,
        user_id: Option<u32>,
    ) -> Result<Self> {
        Client::new(socket, mechanism, server_guid, bus, user_id)
            .perform()
            .await
    }

    /// Create a server-side `Authenticated` for the given `socket`.
    ///
    /// The function takes `client_uid` on Unix and WASI only. On Windows, it takes `client_sid`
    /// instead.
    #[cfg(feature = "p2p")]
    pub async fn server(
        socket: BoxedSplit,
        guid: OwnedGuid,
        #[cfg(any(unix, target_os = "wasi"))] client_uid: Option<u32>,
        #[cfg(windows)] client_sid: Option<String>,
        auth_mechanism: Option<AuthMechanism>,
        unique_name: Option<OwnedUniqueName>,
    ) -> Result<Self> {
        Server::new(
            socket,
            guid,
            #[cfg(any(unix, target_os = "wasi"))]
            client_uid,
            #[cfg(windows)]
            client_sid,
            auth_mechanism,
            unique_name,
        )?
        .perform()
        .await
    }
}

#[async_trait]
pub trait Handshake {
    /// Perform the handshake.
    ///
    /// On a successful handshake, you get an `Authenticated`. If you need to send a Bus Hello,
    /// this remains to be done.
    async fn perform(mut self) -> Result<Authenticated>;
}

fn sasl_auth_id() -> Result<String> {
    #[cfg(unix)]
    {
        Ok(geteuid().as_raw().to_string())
    }

    #[cfg(windows)]
    {
        Ok(win32::ProcessToken::open(None)?.sid()?)
    }

    // A WASI program has no user of its own: the one it authenticates as is the one the other end
    // of the socket knows its host by, which only whoever builds the connection can say.
    #[cfg(target_os = "wasi")]
    {
        Err(Error::Handshake(
            "WASI has no user ID to authenticate with `EXTERNAL` as: set one with \
             `Builder::user_id`"
                .to_owned(),
        ))
    }
}

// The handshake runs over a real socket pair.
#[cfg(all(test, unix, feature = "p2p"))]
mod tests {
    use std::{
        io::{self, Write},
        os::{fd::BorrowedFd, unix::net::UnixStream},
    };

    use futures_util::future::join;
    use ntest::timeout;
    use test_log::test;

    use super::*;
    use crate::{
        Guid, Message,
        connection::socket::{BoxedSplit, Split},
        runtime::{
            Runtime,
            io::{UnixOps, registered},
            test_runtime::under_every_runtime,
        },
    };

    #[test]
    #[timeout(15000)]
    fn handshake() {
        under_every_runtime(|runtime| async move {
            let (p0, p1) = socket_pair(&runtime);

            let guid = OwnedGuid::from(Guid::generate());
            let client = Client::new(p0, None, Some(guid.clone()), false, None);
            let server = Server::new(p1, guid, Some(geteuid().as_raw()), None, None).unwrap();

            let (client, server) =
                join(async move { client.perform().await.unwrap() }, async move {
                    server.perform().await.unwrap()
                })
                .await;

            assert_eq!(client.server_guid, server.server_guid);
            assert_eq!(client.cap_unix_fd, server.cap_unix_fd);
        });
    }

    #[test]
    #[timeout(15000)]
    fn holding_sockets() {
        under_every_runtime(|runtime| async move {
            let (p0, p1) = socket_pair(&runtime);
            let (p0, p1) = (holding(p0), holding(p1));

            let guid = OwnedGuid::from(Guid::generate());
            let client = Client::new(p0, None, Some(guid.clone()), false, None);
            let server = Server::new(p1, guid, Some(geteuid().as_raw()), None, None).unwrap();

            // Neither side would see the other's commands if they stayed held.
            let (mut client, mut server) =
                join(async move { client.perform().await.unwrap() }, async move {
                    server.perform().await.unwrap()
                })
                .await;

            // Nor a message sent once the handshake is done.
            let sent = Message::method_call("/", "Ping")
                .interface("org.freedesktop.DBus.Peer")
                .build(&())
                .unwrap();
            client.socket_write.send_message(&sent).await.unwrap();
            let received = server
                .socket_read
                .as_mut()
                .unwrap()
                .receive_message(
                    0,
                    &mut server.already_received_bytes,
                    &mut server.already_received_fds,
                )
                .await
                .unwrap();

            assert_eq!(received.to_string(), sent.to_string());
        });
    }

    #[test]
    #[timeout(15000)]
    fn pipelined_handshake() {
        let commands = format!(
            "\0AUTH EXTERNAL {}\r\nNEGOTIATE_UNIX_FD\r\nBEGIN\r\n",
            hex::encode(sasl_auth_id().unwrap()),
        );

        under_every_runtime(|runtime| {
            let commands = commands.clone();

            async move {
                let server = server_greeted_with(&runtime, commands.as_bytes(), None);

                assert!(server.await.unwrap().cap_unix_fd);
            }
        });
    }

    #[test]
    #[timeout(15000)]
    fn pipelining_client() {
        under_every_runtime(|runtime| async move {
            let (client, server) = UnixStream::pair().unwrap();
            let guid = OwnedGuid::from(Guid::generate());

            // A server that only answers once it has read the whole of the client's side of the
            // handshake, which a client waiting for an answer to `AUTH` would never send.
            let server = std::thread::spawn({
                let guid = guid.clone();

                move || {
                    let mut received = vec![];
                    while !received.ends_with(b"BEGIN\r\n") {
                        let mut buffer = [0; 1024];
                        let read = std::io::Read::read(&mut &server, &mut buffer).unwrap();
                        assert_ne!(read, 0, "the client hung up halfway through the handshake");
                        received.extend_from_slice(&buffer[..read]);
                    }
                    (&server)
                        .write_all(format!("OK {guid}\r\nAGREE_UNIX_FD\r\n").as_bytes())
                        .unwrap();

                    (received, server)
                }
            });

            let client = Client::new(
                registered(&runtime, client, UnixOps).unwrap().into(),
                None,
                Some(guid),
                false,
                None,
            );
            let authenticated = client.perform().await.unwrap();
            let (received, _server) = server.join().unwrap();

            let expected = format!(
                "\0AUTH EXTERNAL {}\r\nNEGOTIATE_UNIX_FD\r\nBEGIN\r\n",
                hex::encode(sasl_auth_id().unwrap()),
            );
            assert_eq!(received, expected.as_bytes());
            assert!(authenticated.cap_unix_fd);
        });
    }

    #[test]
    #[timeout(15000)]
    fn separate_external_data() {
        let commands = format!(
            "\0AUTH EXTERNAL\r\nDATA {}\r\nBEGIN\r\n",
            hex::encode(sasl_auth_id().unwrap()),
        );

        under_every_runtime(|runtime| {
            let commands = commands.clone();

            async move {
                server_greeted_with(&runtime, commands.as_bytes(), None)
                    .await
                    .unwrap();
            }
        });
    }

    #[test]
    #[timeout(15000)]
    fn missing_external_data() {
        under_every_runtime(|runtime| async move {
            server_greeted_with(&runtime, b"\0AUTH EXTERNAL\r\nDATA\r\nBEGIN\r\n", None)
                .await
                .unwrap();
        });
    }

    #[test]
    #[timeout(15000)]
    fn anonymous_handshake() {
        under_every_runtime(|runtime| async move {
            server_greeted_with(
                &runtime,
                b"\0AUTH ANONYMOUS abcd\r\nBEGIN\r\n",
                Some(AuthMechanism::Anonymous),
            )
            .await
            .unwrap();
        });
    }

    #[test]
    #[timeout(15000)]
    fn separate_anonymous_data() {
        under_every_runtime(|runtime| async move {
            server_greeted_with(
                &runtime,
                b"\0AUTH ANONYMOUS\r\nDATA abcd\r\nBEGIN\r\n",
                Some(AuthMechanism::Anonymous),
            )
            .await
            .unwrap();
        });
    }

    /// A server handshake over a socket a client has already sent `commands` down.
    ///
    /// Everything the client has to say is in the socket before the server reads a byte, which is
    /// what a client that pipelines its commands does.
    fn server_greeted_with(
        runtime: &Runtime,
        commands: &[u8],
        mechanism: Option<AuthMechanism>,
    ) -> impl Future<Output = Result<Authenticated>> {
        let (client, server) = UnixStream::pair().unwrap();
        (&client).write_all(commands).unwrap();

        let server = Server::new(
            registered(runtime, server, UnixOps).unwrap().into(),
            Guid::generate().into(),
            Some(geteuid().as_raw()),
            mechanism,
            None,
        )
        .unwrap();

        async move {
            let authenticated = server.perform().await;
            drop(client);

            authenticated
        }
    }

    /// Both ends of a socket pair, each registered on `runtime`.
    fn socket_pair(runtime: &Runtime) -> (BoxedSplit, BoxedSplit) {
        let (p0, p1) = UnixStream::pair().unwrap();

        (
            registered(runtime, p0, UnixOps).unwrap().into(),
            registered(runtime, p1, UnixOps).unwrap().into(),
        )
    }

    /// `socket`, with a write half that holds on to what it is given until it is flushed.
    fn holding(socket: BoxedSplit) -> BoxedSplit {
        let (read, write) = socket.take();

        Split::new(
            read,
            Box::new(Holding {
                half: write,
                held: vec![],
            }),
        )
    }

    /// A write half that only sends what it is given once it is flushed.
    #[derive(Debug)]
    struct Holding {
        half: Box<dyn WriteHalf>,
        held: Vec<u8>,
    }

    #[async_trait]
    impl WriteHalf for Holding {
        async fn sendmsg(&mut self, buffer: &[u8], fds: &[BorrowedFd<'_>]) -> io::Result<usize> {
            assert!(
                fds.is_empty(),
                "no file descriptors are sent in these tests"
            );
            self.held.extend_from_slice(buffer);

            Ok(buffer.len())
        }

        async fn flush(&mut self) -> io::Result<()> {
            let mut held = &self.held[..];
            while !held.is_empty() {
                let written = self.half.sendmsg(held, &[]).await?;
                held = &held[written..];
            }
            self.held.clear();

            self.half.flush().await
        }

        async fn close(&mut self) -> io::Result<()> {
            self.half.close().await
        }
    }
}