chore(users): grfn -> aspen

Change-Id: I6c6847fac56f0a9a1a2209792e00a3aec5e672b9
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10809
Autosubmit: aspen <root@gws.fyi>
Reviewed-by: sterni <sternenseemann@systemli.org>
Tested-by: BuildkiteCI
Reviewed-by: lukegb <lukegb@tvl.fyi>

users/aspen/xanthous/server/.envrc

@@ -0,0 +1 @@
+eval "$(lorri direnv)"

users/aspen/xanthous/server/.gitignore

@@ -0,0 +1 @@
+target/

users/aspen/xanthous/server/Cargo.toml

@@ -0,0 +1,29 @@
+[package]
+name = "xanthous-server"
+version = "0.1.0"
+edition = "2018"
+
+[dependencies]
+clap = { version = "3.0", features = [ "derive", "env" ] }
+color-eyre = "0.5.11"
+eyre = "0.6.5"
+thrussh = "0.33.5"
+thrussh-keys = "0.21.0"
+tracing = "0.1.29"
+tracing-subscriber = "0.2.25"
+metrics = "0.17.0"
+metrics-exporter-prometheus = "0.6.1"
+futures = "0.3.17"
+libc = "0.2.103"
+nix = "0.23.0"
+
+# Pins for rust 1.55 (2018 edition) until we have 1.56 in nixpkgs-unstable
+pbkdf2 = "<0.9"
+base64ct = "<1.2"
+
+[dependencies.tokio]
+version = "1.13"
+features = ["rt", "rt-multi-thread", "macros", "net", "process", "fs", "signal"]
+
+[dev-dependencies]
+tempfile = "3.2.0"

users/aspen/xanthous/server/default.nix

@@ -0,0 +1,24 @@
+args@{ depot ? import ../../../.. { }
+, pkgs ? depot.third_party.nixpkgs
+, ...
+}:
+
+depot.third_party.naersk.buildPackage {
+  name = "xanthous-server";
+  version = "0.0.1";
+  src = depot.third_party.gitignoreSource ./.;
+
+  # Workaround for a potential Nix bug related to restricted eval.
+  # See https://github.com/nix-community/naersk/issues/169
+  root = depot.nix.sparseTree {
+    root = ./.;
+    paths = [
+      ./Cargo.toml
+      ./Cargo.lock
+    ];
+  };
+
+  passthru = {
+    docker = import ./docker.nix args;
+  };
+}

users/aspen/xanthous/server/docker.nix

@@ -0,0 +1,21 @@
+{ depot ? import ../../../.. { }
+, pkgs ? depot.third_party.nixpkgs
+, ...
+}:
+
+let
+  inherit (depot.users.aspen) xanthous;
+  xanthous-server = xanthous.server;
+in
+pkgs.dockerTools.buildLayeredImage {
+  name = "xanthous-server";
+  tag = "latest";
+  contents = [ xanthous xanthous-server ];
+  config = {
+    Cmd = [
+      "${xanthous-server}/bin/xanthous-server"
+      "--xanthous-binary-path"
+      "${xanthous}/bin/xanthous"
+    ];
+  };
+}

users/aspen/xanthous/server/module.nix

@@ -0,0 +1,49 @@
+{ config, lib, pkgs, depot, ... }:
+
+let
+  cfg = config.services.xanthous-server;
+in
+{
+  options = with lib; {
+    services.xanthous-server = {
+      enable = mkEnableOption "xanthous server";
+
+      port = mkOption {
+        type = types.int;
+        default = 2222;
+        description = "Port to listen to for SSH connections";
+      };
+
+      metricsPort = mkOption {
+        type = types.int;
+        default = 9000;
+        description = "Port to listen to for prometheus metrics";
+      };
+
+      image = mkOption {
+        type = types.package;
+        default = depot.users.aspen.xanthous.server.docker;
+        description = "OCI image file to run";
+      };
+
+      ed25519SecretKeyFile = mkOption {
+        type = with types; uniq string;
+        description = "Path to the ed25519 secret key for the server";
+      };
+    };
+  };
+
+  config = lib.mkIf cfg.enable {
+    virtualisation.oci-containers.containers."xanthous-server" = {
+      autoStart = true;
+      image = "${cfg.image.imageName}:${cfg.image.imageTag}";
+      imageFile = cfg.image;
+      ports = [
+        "${toString cfg.port}:22"
+        "${toString cfg.metricsPort}:9000"
+      ];
+      environment.SECRET_KEY_FILE = "/secret-key";
+      volumes = [ "/etc/secrets/xanthous-server-secret-key:/secret-key" ];
+    };
+  };
+}

users/aspen/xanthous/server/shell.nix

@@ -0,0 +1,11 @@
+let
+  depot = import ../../../.. { };
+  pkgs = depot.third_party.nixpkgs;
+in
+
+pkgs.mkShell {
+  buildInputs = with pkgs; [
+    rustup
+    rust-analyzer
+  ];
+}

users/aspen/xanthous/server/src/main.rs

@@ -0,0 +1,385 @@
+use std::net::SocketAddr;
+use std::path::PathBuf;
+use std::pin::Pin;
+use std::process::Command;
+use std::str;
+use std::sync::Arc;
+
+use clap::Parser;
+use color_eyre::eyre::Result;
+use eyre::{bail, Context};
+use futures::future::{ready, Ready};
+use futures::Future;
+use metrics_exporter_prometheus::PrometheusBuilder;
+use nix::pty::Winsize;
+use pty::ChildHandle;
+use thrussh::server::{self, Auth, Session};
+use thrussh::{ChannelId, CryptoVec};
+use thrussh_keys::decode_secret_key;
+use thrussh_keys::key::KeyPair;
+use tokio::fs::File;
+use tokio::io::{AsyncReadExt, AsyncWriteExt};
+use tokio::net::TcpListener;
+use tokio::select;
+use tokio::time::Instant;
+use tracing::{debug, error, info, info_span, trace, warn, Instrument};
+use tracing_subscriber::EnvFilter;
+
+use crate::pty::WaitPid;
+
+mod metrics;
+mod pty;
+
+use crate::metrics::reported::*;
+use crate::metrics::{decrement_gauge, histogram, increment_counter, increment_gauge};
+
+/// SSH-compatible server for playing Xanthous
+#[derive(Parser, Debug)]
+struct Opts {
+    /// Address to bind to
+    #[clap(long, short = 'a', default_value = "0.0.0.0:22")]
+    address: String,
+
+    /// Address to listen to for metrics
+    #[clap(long, default_value = "0.0.0.0:9000")]
+    metrics_address: SocketAddr,
+
+    /// Format to use when emitting log events
+    #[clap(
+        long,
+        env = "LOG_FORMAT",
+        default_value = "full",
+        possible_values = &["compact", "full", "pretty", "json"]
+    )]
+    log_format: String,
+
+    /// Full path to the xanthous binary
+    #[clap(long, env = "XANTHOUS_BINARY_PATH")]
+    xanthous_binary_path: String,
+
+    /// Path to a file containing the ed25519 secret key for the server
+    #[clap(long, env = "SECRET_KEY_FILE")]
+    secret_key_file: PathBuf,
+
+    /// Level to log at
+    #[clap(long, env = "LOG_LEVEL", default_value = "info")]
+    log_level: String,
+}
+
+impl Opts {
+    async fn read_secret_key(&self) -> Result<KeyPair> {
+        let mut file = File::open(&self.secret_key_file)
+            .await
+            .context("Reading secret key file")?;
+        let mut secret_key = Vec::with_capacity(464);
+        file.read_to_end(&mut secret_key).await?;
+        Ok(decode_secret_key(str::from_utf8(&secret_key)?, None)?)
+    }
+
+    async fn ssh_server_config(&self) -> Result<server::Config> {
+        let key_pair = self.read_secret_key().await?;
+
+        Ok(server::Config {
+            server_id: "SSH-2.0-xanthous".to_owned(),
+            keys: vec![key_pair],
+            ..Default::default()
+        })
+    }
+
+    fn init_logging(&self) -> Result<()> {
+        let filter = EnvFilter::try_new(&self.log_level)?;
+        let s = tracing_subscriber::fmt().with_env_filter(filter);
+
+        match self.log_format.as_str() {
+            "compact" => s.compact().init(),
+            "full" => s.init(),
+            "pretty" => s.pretty().init(),
+            "json" => s.json().with_current_span(true).init(),
+            f => bail!("Invalid log format `{}`", f),
+        }
+
+        Ok(())
+    }
+}
+
+struct Handler {
+    address: SocketAddr,
+    xanthous_binary_path: &'static str,
+    username: Option<String>,
+    child: Option<ChildHandle>,
+}
+
+async fn run_child(
+    mut child: pty::Child,
+    mut server_handle: server::Handle,
+    channel_id: ChannelId,
+) -> Result<()> {
+    let mut buf = [0; 2048];
+    loop {
+        select! {
+            r = child.tty.read(&mut buf)  => {
+                let read_bytes = r?;
+                if read_bytes == 0 {
+                    info!("EOF received from process");
+                    let _ = server_handle.close(channel_id).await;
+                    return Ok(())
+                } else {
+                    trace!(?read_bytes, "read bytes from child");
+                    let _ = server_handle.data(channel_id, CryptoVec::from_slice(&buf[..read_bytes])).await;
+                }
+            }
+            status = WaitPid::new(child.pid) => {
+                match status {
+                    Ok(_status) => info!("Child exited"),
+                    Err(error) => error!(%error, "Child failed"),
+                }
+                let _ = server_handle.close(channel_id).await;
+                return Ok(())
+            }
+        }
+    }
+}
+
+impl Handler {
+    async fn spawn_shell(
+        &mut self,
+        mut handle: server::Handle,
+        channel_id: ChannelId,
+        term: String,
+        winsize: Winsize,
+    ) -> Result<()> {
+        let mut cmd = Command::new(self.xanthous_binary_path);
+        cmd.env("TERM", term);
+        if let Some(username) = &self.username {
+            cmd.args(["--name", username]);
+        }
+        cmd.arg("--disable-saving");
+
+        let child = pty::spawn(cmd, Some(winsize), None).await?;
+        info!(pid = %child.pid, "Spawned child");
+        increment_gauge!(RUNNING_PROCESSES, 1.0);
+        self.child = Some(child.handle().await?);
+        tokio::spawn(
+            async move {
+                let span = info_span!("child", pid = %child.pid);
+                if let Err(error) = run_child(child, handle.clone(), channel_id)
+                    .instrument(span.clone())
+                    .await
+                {
+                    span.in_scope(|| error!(%error, "Error running child"));
+                    let _ = handle.close(channel_id).await;
+                }
+                decrement_gauge!(RUNNING_PROCESSES, 1.0);
+            }
+            .in_current_span(),
+        );
+        Ok(())
+    }
+}
+
+#[allow(clippy::type_complexity)]
+impl server::Handler for Handler {
+    type Error = eyre::Error;
+    type FutureAuth = Ready<Result<(Self, Auth)>>;
+    type FutureUnit = Pin<Box<dyn Future<Output = Result<(Self, Session)>> + Send + 'static>>;
+    type FutureBool = Ready<Result<(Self, Session, bool)>>;
+
+    fn finished_auth(self, auth: Auth) -> Self::FutureAuth {
+        ready(Ok((self, auth)))
+    }
+
+    fn finished_bool(self, b: bool, session: Session) -> Self::FutureBool {
+        ready(Ok((self, session, b)))
+    }
+
+    fn finished(self, session: Session) -> Self::FutureUnit {
+        Box::pin(ready(Ok((self, session))))
+    }
+
+    fn auth_none(mut self, username: &str) -> Self::FutureAuth {
+        info!(%username, "Accepted new connection");
+        self.username = Some(username.to_owned());
+        self.finished_auth(Auth::Accept)
+    }
+
+    fn auth_password(mut self, username: &str, _password: &str) -> Self::FutureAuth {
+        info!(%username, "Accepted new connection");
+        self.username = Some(username.to_owned());
+        self.finished_auth(Auth::Accept)
+    }
+
+    fn auth_publickey(
+        mut self,
+        username: &str,
+        _: &thrussh_keys::key::PublicKey,
+    ) -> Self::FutureAuth {
+        info!(%username, "Accepted new connection");
+        self.username = Some(username.to_owned());
+        self.finished_auth(Auth::Accept)
+    }
+
+    fn pty_request(
+        mut self,
+        channel: thrussh::ChannelId,
+        term: &str,
+        col_width: u32,
+        row_height: u32,
+        pix_width: u32,
+        pix_height: u32,
+        modes: &[(thrussh::Pty, u32)],
+        session: Session,
+    ) -> Self::FutureUnit {
+        let term = term.to_owned();
+        let modes = modes.to_vec();
+        Box::pin(async move {
+            debug!(
+                %term,
+                %col_width,
+                %row_height,
+                %pix_width,
+                %pix_height,
+                ?modes,
+                "PTY Requested"
+            );
+
+            self.spawn_shell(
+                session.handle(),
+                channel,
+                term,
+                Winsize {
+                    ws_row: row_height as _,
+                    ws_col: col_width as _,
+                    ws_xpixel: pix_width as _,
+                    ws_ypixel: pix_height as _,
+                },
+            )
+            .await?;
+
+            Ok((self, session))
+        })
+    }
+
+    fn window_change_request(
+        mut self,
+        _channel: ChannelId,
+        col_width: u32,
+        row_height: u32,
+        pix_width: u32,
+        pix_height: u32,
+        session: Session,
+    ) -> Self::FutureUnit {
+        Box::pin(async move {
+            if let Some(child) = self.child.as_mut() {
+                trace!(%row_height, %col_width, "Window resize request received");
+                child
+                    .resize_window(Winsize {
+                        ws_row: row_height as _,
+                        ws_col: col_width as _,
+                        ws_xpixel: pix_width as _,
+                        ws_ypixel: pix_height as _,
+                    })
+                    .await?;
+            } else {
+                warn!("Resize request received without child process; ignoring");
+            }
+
+            Ok((self, session))
+        })
+    }
+
+    fn data(
+        mut self,
+        _channel: thrussh::ChannelId,
+        data: &[u8],
+        session: Session,
+    ) -> Self::FutureUnit {
+        trace!(data = %String::from_utf8_lossy(data), raw_data = ?data);
+        let data = data.to_owned();
+        Box::pin(async move {
+            if let Some(child) = self.child.as_mut() {
+                child.write_all(&data).await?;
+            } else {
+                warn!("Data received without child process; ignoring");
+            }
+
+            Ok((self, session))
+        })
+    }
+}
+
+#[tokio::main]
+async fn main() -> Result<()> {
+    color_eyre::install()?;
+    let opts = Box::leak::<'static>(Box::new(Opts::parse()));
+    opts.init_logging()?;
+    PrometheusBuilder::new()
+        .listen_address(opts.metrics_address)
+        .install()?;
+    metrics::register();
+
+    let config = Arc::new(opts.ssh_server_config().await?);
+    info!(address = %opts.address, "Listening for new SSH connections");
+    let listener = TcpListener::bind(&opts.address).await?;
+
+    loop {
+        let (stream, address) = listener.accept().await?;
+        increment_counter!(CONNECTIONS_ACCEPTED);
+        increment_gauge!(ACTIVE_CONNECTIONS, 1.0);
+        let config = config.clone();
+        let handler = Handler {
+            xanthous_binary_path: &opts.xanthous_binary_path,
+            address,
+            username: None,
+            child: None,
+        };
+        tokio::spawn(async move {
+            let span = info_span!("client", address = %handler.address);
+            let start = Instant::now();
+            if let Err(error) = server::run_stream(config, stream, handler)
+                .instrument(span.clone())
+                .await
+            {
+                span.in_scope(|| error!(%error));
+            }
+            let duration = start.elapsed();
+            span.in_scope(|| info!(duration_ms = %duration.as_millis(), "Client disconnected"));
+            histogram!(CONNECTION_DURATION, duration);
+            decrement_gauge!(ACTIVE_CONNECTIONS, 1.0);
+        });
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use tempfile::NamedTempFile;
+
+    use super::*;
+
+    #[tokio::test]
+    async fn read_secret_key() {
+        use std::io::Write;
+
+        let mut file = NamedTempFile::new().unwrap();
+        file.write_all(
+            b"
+-----BEGIN OPENSSH PRIVATE KEY-----
+b3BlbnNzaC1rZXktdjEAAAAABG5vbmUAAAAEbm9uZQAAAAAAAAABAAAAMwAAAAtzc2gtZW
+QyNTUxOQAAACAYz80xcK7jYxZMAl6apIHKRtB0Z2U78gG39c1QaIhgMwAAAJB9vxK9fb8S
+vQAAAAtzc2gtZWQyNTUxOQAAACAYz80xcK7jYxZMAl6apIHKRtB0Z2U78gG39c1QaIhgMw
+AAAEDNZ0d3lLNBGU6Im4JOpr490TOjm+cB7kMVXjVg3iCowBjPzTFwruNjFkwCXpqkgcpG
+0HRnZTvyAbf1zVBoiGAzAAAACHRlc3Qta2V5AQIDBAU=
+-----END OPENSSH PRIVATE KEY-----
+",
+        )
+        .unwrap();
+
+        let opts: Opts = Opts::parse_from(&[
+            "xanthous-server".as_ref(),
+            "--xanthous-binary-path".as_ref(),
+            "/bin/xanthous".as_ref(),
+            "--secret-key-file".as_ref(),
+            file.path().as_os_str(),
+        ]);
+        opts.read_secret_key().await.unwrap();
+    }
+}

users/aspen/xanthous/server/src/metrics.rs

@@ -0,0 +1,24 @@
+pub use ::metrics::*;
+
+pub mod reported {
+    /// Counter: Connections accepted on the TCP listener
+    pub const CONNECTIONS_ACCEPTED: &str = "ssh.connections.accepted";
+
+    /// Histogram: Connection duration
+    pub const CONNECTION_DURATION: &str = "ssh.connections.duration";
+
+    /// Gauge: Currently active connections
+    pub const ACTIVE_CONNECTIONS: &str = "ssh.connections.active";
+
+    /// Gauge: Currently running xanthous processes
+    pub const RUNNING_PROCESSES: &str = "ssh.child.processes";
+}
+
+pub fn register() {
+    use reported::*;
+
+    register_counter!(CONNECTIONS_ACCEPTED);
+    register_histogram!(CONNECTION_DURATION);
+    register_gauge!(ACTIVE_CONNECTIONS);
+    register_gauge!(RUNNING_PROCESSES);
+}

users/aspen/xanthous/server/src/pty.rs

@@ -0,0 +1,172 @@
+use std::io::{self};
+use std::os::unix::prelude::{AsRawFd, CommandExt, FromRawFd};
+use std::pin::Pin;
+use std::process::{abort, Command};
+use std::task::{Context, Poll};
+
+use eyre::{bail, Result};
+use futures::Future;
+use nix::pty::{forkpty, Winsize};
+use nix::sys::termios::Termios;
+use nix::sys::wait::{waitpid, WaitPidFlag, WaitStatus};
+use nix::unistd::{ForkResult, Pid};
+use tokio::fs::File;
+use tokio::io::{AsyncRead, AsyncWrite};
+use tokio::signal::unix::{signal, Signal, SignalKind};
+use tokio::task::spawn_blocking;
+
+mod ioctl {
+    use super::Winsize;
+    use libc::TIOCSWINSZ;
+    use nix::ioctl_write_ptr_bad;
+
+    ioctl_write_ptr_bad!(tiocswinsz, TIOCSWINSZ, Winsize);
+}
+
+async fn asyncify<F, T>(f: F) -> Result<T>
+where
+    F: FnOnce() -> Result<T> + Send + 'static,
+    T: Send + 'static,
+{
+    match spawn_blocking(f).await {
+        Ok(res) => res,
+        Err(_) => bail!("background task failed",),
+    }
+}
+
+pub struct Child {
+    pub tty: File,
+    pub pid: Pid,
+}
+
+pub struct ChildHandle {
+    pub tty: File,
+}
+
+pub struct WaitPid {
+    pid: Pid,
+    signal: Signal,
+}
+
+impl WaitPid {
+    pub fn new(pid: Pid) -> Self {
+        Self {
+            pid,
+            signal: signal(SignalKind::child()).unwrap(),
+        }
+    }
+}
+
+impl Future for WaitPid {
+    type Output = nix::Result<WaitStatus>;
+
+    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        let _ = self.signal.poll_recv(cx);
+        match waitpid(self.pid, Some(WaitPidFlag::WNOHANG)) {
+            Ok(WaitStatus::StillAlive) => Poll::Pending,
+            result => Poll::Ready(result),
+        }
+    }
+}
+
+impl Child {
+    pub async fn handle(&self) -> io::Result<ChildHandle> {
+        Ok(ChildHandle {
+            tty: self.tty.try_clone().await?,
+        })
+    }
+}
+
+impl ChildHandle {
+    pub async fn resize_window(&mut self, winsize: Winsize) -> Result<()> {
+        let fd = self.tty.as_raw_fd();
+        asyncify(move || unsafe {
+            ioctl::tiocswinsz(fd, &winsize as *const Winsize)?;
+            Ok(())
+        })
+        .await
+    }
+}
+
+pub async fn spawn(
+    mut cmd: Command,
+    winsize: Option<Winsize>,
+    termios: Option<Termios>,
+) -> Result<Child> {
+    asyncify(move || unsafe {
+        let res = forkpty(winsize.as_ref(), termios.as_ref())?;
+        match res.fork_result {
+            ForkResult::Parent { child } => Ok(Child {
+                pid: child,
+                tty: File::from_raw_fd(res.master),
+            }),
+            ForkResult::Child => {
+                cmd.exec();
+                abort();
+            }
+        }
+    })
+    .await
+}
+
+impl AsyncRead for Child {
+    fn poll_read(
+        mut self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        buf: &mut tokio::io::ReadBuf<'_>,
+    ) -> Poll<io::Result<()>> {
+        Pin::new(&mut self.tty).poll_read(cx, buf)
+    }
+}
+
+impl AsyncWrite for Child {
+    fn poll_write(
+        mut self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        buf: &[u8],
+    ) -> Poll<Result<usize, io::Error>> {
+        Pin::new(&mut self.tty).poll_write(cx, buf)
+    }
+
+    fn poll_flush(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), io::Error>> {
+        Pin::new(&mut self.tty).poll_flush(cx)
+    }
+
+    fn poll_shutdown(
+        mut self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+    ) -> Poll<Result<(), io::Error>> {
+        Pin::new(&mut self.tty).poll_shutdown(cx)
+    }
+}
+
+impl AsyncRead for ChildHandle {
+    fn poll_read(
+        mut self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        buf: &mut tokio::io::ReadBuf<'_>,
+    ) -> Poll<io::Result<()>> {
+        Pin::new(&mut self.tty).poll_read(cx, buf)
+    }
+}
+
+impl AsyncWrite for ChildHandle {
+    fn poll_write(
+        mut self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        buf: &[u8],
+    ) -> Poll<Result<usize, io::Error>> {
+        Pin::new(&mut self.tty).poll_write(cx, buf)
+    }
+
+    fn poll_flush(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), io::Error>> {
+        Pin::new(&mut self.tty).poll_flush(cx)
+    }
+
+    fn poll_shutdown(
+        mut self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+    ) -> Poll<Result<(), io::Error>> {
+        Pin::new(&mut self.tty).poll_shutdown(cx)
+    }
+}