Persist sessions across server restarts via per-session holders
Make dosh terminal sessions survive a dosh-server restart (crash/upgrade/systemctl restart): a reattaching client lands on the SAME shell with screen state intact, instead of a fresh one. Design: when persist_sessions is on (new config, default true) each terminal session's shell runs in a small detached per-session holder process (the dosh-server binary re-exec'd as `dosh-server hold`). The holder double-forks + setsid into its own session, opens the PTY, spawns the shell as ITS child, and serves the PTY master fd over a per-session Unix socket via SCM_RIGHTS. The server adopts that fd to build a PtyHandle that DETACHES (does not kill the shell) on drop, so a server exit leaves holder + shell alive. On startup the server scans the runtime dir under sessions_dir/run, reconnects to each live holder, receives the master fd again, restores the persisted vt100 screen, and rebuilds the Session. Screen/scrollback (server-memory only) is mirrored to disk atomically: byte-throttled on the output hot path plus a 2s periodic flush, and restored on re-adoption so reattach repaints. Truly-abandoned persistent sessions are still reaped per the existing grace logic by asking the holder to shut down. Anything in the persistent path failing degrades gracefully to the original in-process shell. PtyHandle gains an Owned (kill-on-drop, unchanged default) vs Adopted (detach-on-drop) backing; resize on an adopted master uses TIOCSWINSZ. No wire-format change, so protocol::VERSION stays 3. New deps: libc (direct). New config: persist_sessions (default true); existing integration tests pin it false to keep exercising the non-persistent path unchanged. Adds tests/integration_smoke.rs::session_survives_server_restart_same_ shell_and_screen: attaches, sets `cd /tmp; export MARK=...`, paints a screen marker, KILLs the server, restarts it on the same config, reattaches and asserts same shell pid + MARK + PWD + restored screen. Plus persist.rs unit tests (name round-trip, screen save/load, dead-holder scan cleanup, SCM_RIGHTS fd round-trip). cargo fmt --check and cargo test green. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
This commit is contained in:
DuProcess
Generated
+1
@@ -448,6 +448,7 @@ dependencies = [
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"ed25519-dalek",
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"hkdf",
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"hmac",
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"libc",
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"portable-pty",
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"rand",
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"rpassword",
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@@ -16,6 +16,7 @@ dirs = "5.0"
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ed25519-dalek = "2.1"
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hkdf = "0.12"
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hmac = "0.12"
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libc = "0.2"
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portable-pty = "0.8"
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rand = "0.8"
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rpassword = "7.5.4"
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@@ -81,6 +81,9 @@ dosh-server
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client table per session
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encrypted UDP protocol
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tiny SSH-invoked dosh-auth helper mode
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persistent sessions (persist_sessions, default on): each shell runs in a
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detached per-session holder process; the server adopts its PTY master fd via
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SCM_RIGHTS and re-adopts it after a restart, so sessions survive crash/upgrade
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dosh-client
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terminal raw mode
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@@ -123,8 +123,13 @@ Native v1 must be boring under real use:
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- A closed laptop must not kill the remote session.
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- A client crash must not kill the remote session.
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- Server restart may drop live PTYs in v1 unless session persistence is implemented,
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but the client must fail clearly and reconnect cleanly afterward.
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- A server restart must not kill the remote session when `persist_sessions` is on
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(the default): each session's shell runs in a detached per-session *holder*
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process whose PTY master fd the server passes back to itself via SCM_RIGHTS, so
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the shell + scrollback survive a server crash/upgrade/`systemctl restart` and a
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reattaching client lands on the same shell with its screen restored. With
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`persist_sessions = false` the old behavior applies: live PTYs drop on restart,
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but the client must still fail clearly and reconnect cleanly afterward.
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- Decrypt failures from stale packets must be ignored or trigger reconnect, never
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terminate the terminal by themselves.
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- Terminal cleanup must restore cursor, mouse mode, bracketed paste, alternate
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+357
-29
@@ -4,13 +4,14 @@ use dosh::auth::{
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build_attach_ticket, build_bootstrap, encode_bootstrap, load_or_create_server_secret, now_secs,
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open_attach_ticket, verify_bootstrap,
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};
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use dosh::config::{ServerConfig, load_server_config};
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use dosh::config::{ServerConfig, expand_tilde, load_server_config};
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use dosh::crypto;
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use dosh::native::{
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EnvVar, ForwardingKind, ForwardingRequest, NativeAuthOk, NativeServerHello,
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derive_native_session_key, generate_native_ephemeral, host_public_key, host_public_key_line,
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load_or_create_host_key, sign_server_hello, verify_native_user_auth_from_config,
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};
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use dosh::persist;
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use dosh::protocol::{
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self, AttachOk, AttachReject, BootstrapAttachRequest, CLIENT_TO_SERVER, Frame, Input,
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NativeAuthCheckOkBody, NativeAuthOkBody, NativeClientHelloBody, NativeServerHelloBody,
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@@ -18,10 +19,11 @@ use dosh::protocol::{
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StreamClose, StreamData, StreamOpen, StreamOpenOk, StreamOpenReject, StreamWindowAdjust,
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TicketAttachBody, TicketAttachEnvelope, TicketAttachOkEnvelope,
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};
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use dosh::pty::{PtyHandle, PtyOutput, spawn_pty_session};
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use dosh::pty::{PtyHandle, PtyOutput, adopt_pty_from_fd, spawn_pty_session};
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use std::collections::{HashMap, HashSet, VecDeque};
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use std::net::{IpAddr, SocketAddr};
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use std::os::unix::fs::PermissionsExt;
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use std::os::unix::net::UnixStream as StdUnixStream;
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use std::path::PathBuf;
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use std::sync::atomic::{AtomicU64, Ordering};
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use std::sync::{Arc, Mutex};
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@@ -32,6 +34,11 @@ use tokio::sync::mpsc;
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const STREAM_INITIAL_WINDOW: usize = 1024 * 1024;
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/// Persist a persistent session's screen to disk after this many bytes of output
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/// have accumulated since the last mirror. Keeps the atomic write off the
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/// per-packet hot path while bounding how much fresh output a crash can lose.
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const SCREEN_PERSIST_BYTES: usize = 4096;
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/// Sentinel `target_host` sent to the client on a server-initiated `StreamOpen`
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/// that carries an SSH-agent connection (the client splices it into its local
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/// `SSH_AUTH_SOCK` rather than dialing TCP). Must match the client's constant.
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@@ -74,13 +81,55 @@ enum Command {
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#[arg(long)]
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udp_host: Option<String>,
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},
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/// Internal: run as a per-session shell holder so the shell survives a
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/// server restart. Spawned by the server itself; not meant to be run by
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/// hand. Daemonizes, owns the PTY, and serves the master fd over a socket.
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#[command(hide = true)]
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Hold {
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#[arg(long)]
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runtime_dir: PathBuf,
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#[arg(long)]
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session: String,
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#[arg(long)]
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shell: String,
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#[arg(long)]
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cols: u16,
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#[arg(long)]
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rows: u16,
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/// `NAME=VALUE` pairs for the shell environment. Repeatable.
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#[arg(long = "env")]
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env: Vec<String>,
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},
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}
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#[tokio::main(flavor = "current_thread")]
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async fn main() -> Result<()> {
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fn main() -> Result<()> {
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let args = Args::parse();
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match args.command {
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// The holder is handled BEFORE any tokio runtime exists: it forks/setsids to
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// daemonize, and forking out of a live async runtime is best avoided. It also
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// never uses tokio, so it has no reason to pay for one.
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if let Command::Hold {
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runtime_dir,
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session,
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shell,
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cols,
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rows,
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env,
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} = &args.command
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{
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let env = parse_env_pairs(env)?;
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return persist::run_holder(runtime_dir, session, shell, *cols, *rows, &env);
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}
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let runtime = tokio::runtime::Builder::new_current_thread()
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.enable_all()
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.build()
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.context("build tokio runtime")?;
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runtime.block_on(async move { run_command(args.command).await })
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}
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async fn run_command(command: Command) -> Result<()> {
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match command {
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Command::Serve { config } => serve(config).await,
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Command::Hold { .. } => unreachable!("Hold is handled before the runtime starts"),
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Command::Auth {
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protocol,
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nonce,
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@@ -130,6 +179,12 @@ async fn serve(config_path: Option<std::path::PathBuf>) -> Result<()> {
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)));
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{
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let mut locked = state.lock().expect("server state poisoned");
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// Re-adopt any persistent sessions whose holders survived a previous
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// server's exit, BEFORE prewarming, so a prewarmed name reattaches to
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// its existing shell instead of spawning a duplicate.
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if config.persist_sessions {
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locked.readopt_persistent_sessions();
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}
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for session in config.prewarm_sessions.clone() {
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locked.ensure_session(&session, 80, 24, "read-write", &[])?;
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}
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@@ -169,6 +224,21 @@ async fn serve(config_path: Option<std::path::PathBuf>) -> Result<()> {
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}
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});
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// Periodically mirror persistent sessions' screens to disk, bounding how much
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// recent output a sudden crash can lose regardless of throughput (the
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// per-packet path only persists every few KB). Cheap: one atomic write per
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// persistent session per tick, and only when its screen changed.
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if config.persist_sessions {
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let flush_state = Arc::clone(&state);
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tokio::spawn(async move {
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let mut interval = tokio::time::interval(Duration::from_secs(2));
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loop {
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interval.tick().await;
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flush_persistent_screens(&flush_state);
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}
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});
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}
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let mut buf = vec![0u8; 65535];
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loop {
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let (n, peer) = socket.recv_from(&mut buf).await?;
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@@ -273,6 +343,19 @@ struct Session {
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/// sessions (and their shells) after a grace period. `None` while at least
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/// one client is attached.
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empty_since: Option<Instant>,
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/// Open control connection to this session's holder process, when the shell
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/// runs persistently out-of-process. Dropping it (server exit) leaves the
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/// holder running; sending a shutdown byte over it reaps the holder. `None`
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/// for non-persistent (in-process) sessions.
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holder_control: Option<StdUnixStream>,
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/// Whether this session's shell lives in a holder process (persistent).
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persistent: bool,
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/// Bytes of session output since the screen was last mirrored to disk, used
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/// to throttle the (atomic) screen-persistence writes.
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bytes_since_persist: usize,
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/// `output_seq` at the last successful screen mirror, so the periodic flush
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/// skips sessions whose screen has not changed.
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last_persisted_seq: u64,
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}
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#[derive(Clone)]
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@@ -347,30 +430,29 @@ impl ServerState {
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requested_env: &[EnvVar],
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) -> Result<()> {
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let env = accepted_env(&self.config, requested_env)?;
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// Whether this existing session needs a (re)spawned PTY. Computed without
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// holding a mutable borrow of `self.sessions` so we can call the
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// `&self`-borrowing spawn helper.
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let needs_pty = self
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.sessions
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.get(name)
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.map(|session| session.pty.is_none() && mode_uses_pty(mode));
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if let Some(needs_pty) = needs_pty {
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if needs_pty {
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let (pty, control, persistent) = self.spawn_session_pty(name, cols, rows, &env)?;
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if let Some(session) = self.sessions.get_mut(name) {
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if session.pty.is_none() && mode_uses_pty(mode) {
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session.pty = Some(spawn_pty_session(
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name.to_string(),
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&self.config.shell,
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cols.max(1),
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rows.max(1),
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&env,
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self.pty_tx.clone(),
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)?);
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session.pty = Some(pty);
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session.holder_control = control;
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session.persistent = persistent;
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}
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}
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return Ok(());
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}
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let pty = if mode_uses_pty(mode) {
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Some(spawn_pty_session(
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name.to_string(),
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&self.config.shell,
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cols.max(1),
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rows.max(1),
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&env,
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self.pty_tx.clone(),
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)?)
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let (pty, control, persistent) = if mode_uses_pty(mode) {
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let (pty, control, persistent) = self.spawn_session_pty(name, cols, rows, &env)?;
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(Some(pty), control, persistent)
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} else {
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None
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(None, None, false)
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};
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self.sessions.insert(
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name.to_string(),
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@@ -381,11 +463,144 @@ impl ServerState {
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output_seq: 0,
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recent: VecDeque::with_capacity(self.config.scrollback),
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empty_since: None,
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holder_control: control,
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persistent,
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bytes_since_persist: 0,
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last_persisted_seq: 0,
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},
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);
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Ok(())
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}
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/// Spawn (or, in the persistent case, spawn-and-adopt) a PTY for a session.
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///
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/// With `persist_sessions` on, the shell is launched in a detached holder
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/// process whose PTY master fd is passed back via SCM_RIGHTS, so the shell
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/// outlives this server. If anything in that path fails we degrade
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/// gracefully to the original in-process spawn (a shell that dies with the
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/// server), so persistence never makes a session un-attachable.
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fn spawn_session_pty(
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&self,
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name: &str,
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cols: u16,
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rows: u16,
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env: &[(String, String)],
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) -> Result<(PtyHandle, Option<StdUnixStream>, bool)> {
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let cols = cols.max(1);
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let rows = rows.max(1);
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if self.config.persist_sessions {
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match self.spawn_persistent_pty(name, cols, rows, env) {
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Ok(pair) => return Ok((pair.0, Some(pair.1), true)),
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Err(err) => {
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eprintln!(
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"persistence unavailable for session {name}, using in-process shell: {err:#}"
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);
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}
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}
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}
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let pty = spawn_pty_session(
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name.to_string(),
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&self.config.shell,
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cols,
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rows,
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env,
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self.pty_tx.clone(),
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)?;
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Ok((pty, None, false))
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}
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/// Spawn a fresh holder for `name` and adopt its PTY master fd.
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fn spawn_persistent_pty(
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&self,
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name: &str,
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cols: u16,
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rows: u16,
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env: &[(String, String)],
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) -> Result<(PtyHandle, StdUnixStream)> {
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let sessions_dir = self.sessions_dir();
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persist::spawn_holder(&sessions_dir, name, &self.config.shell, cols, rows, env)?;
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self.adopt_persistent_pty(name)
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}
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/// Connect to an existing holder for `name` and build an adopted PtyHandle
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/// from the master fd it hands back. Used both right after spawning a holder
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/// and when re-adopting a holder left behind by a previous server.
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fn adopt_persistent_pty(&self, name: &str) -> Result<(PtyHandle, StdUnixStream)> {
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let sessions_dir = self.sessions_dir();
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let (fd, control) = persist::adopt_holder(&sessions_dir, name)?;
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let pty = match adopt_pty_from_fd(name.to_string(), fd, self.pty_tx.clone()) {
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Ok(pty) => pty,
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Err(err) => {
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// We own `fd`; close it so the failed adopt doesn't leak it.
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drop(persist::fd_into_file(fd));
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return Err(err);
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}
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};
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Ok((pty, control))
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}
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fn sessions_dir(&self) -> PathBuf {
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expand_tilde(&self.config.sessions_dir)
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}
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/// On startup, re-adopt persistent sessions whose holder processes outlived a
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/// previous server. For each live holder we reconnect, receive the PTY master
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/// fd, restore the persisted screen/scrollback, and rebuild the in-memory
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/// `Session` so a reattaching client lands on the same shell with its screen
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/// intact. A holder we cannot adopt is left for the cleanup pass / fresh
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/// re-create, never crashing startup.
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fn readopt_persistent_sessions(&mut self) {
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let sessions_dir = self.sessions_dir();
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let holders = persist::scan_existing_holders(&sessions_dir);
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for meta in holders {
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let name = meta.session.clone();
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if self.sessions.contains_key(&name) {
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continue;
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}
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let (pty, control) = match self.adopt_persistent_pty(&name) {
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Ok(pair) => pair,
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Err(err) => {
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eprintln!("could not re-adopt session {name}: {err:#}");
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persist::remove_runtime_dir(&sessions_dir, &name);
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continue;
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}
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};
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// Restore screen + scrollback geometry/seq if we saved one. The
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// restored snapshot is replayed into a fresh parser so a reattaching
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// client (and `screen_snapshot`) sees the pre-restart screen.
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let saved = persist::load_screen(&sessions_dir, &name);
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let (cols, rows) = saved
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.as_ref()
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.map(|s| (s.cols.max(1), s.rows.max(1)))
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.unwrap_or((80, 24));
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let mut parser = vt100::Parser::new(rows, cols, self.config.scrollback);
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let mut output_seq = 0;
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if let Some(saved) = saved {
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parser.process(&saved.snapshot);
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output_seq = saved.output_seq;
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}
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self.sessions.insert(
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name.clone(),
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Session {
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pty: Some(pty),
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parser,
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clients: HashMap::new(),
|
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output_seq,
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recent: VecDeque::with_capacity(self.config.scrollback),
|
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empty_since: Some(Instant::now()),
|
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holder_control: Some(control),
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persistent: true,
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bytes_since_persist: 0,
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||||
last_persisted_seq: output_seq,
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},
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);
|
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eprintln!(
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"re-adopted persistent session {name} (shell pid {})",
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meta.shell_pid
|
||||
);
|
||||
}
|
||||
}
|
||||
|
||||
/// Insert a client into `session_name` and record it in the O(1) index. The
|
||||
/// session must already exist (callers `ensure_session` first).
|
||||
fn insert_client(&mut self, session_name: &str, client_id: [u8; 16], client: ClientState) {
|
||||
@@ -2240,6 +2455,7 @@ async fn broadcast_output(
|
||||
return broadcast_session_exit(state, socket, output.session).await;
|
||||
}
|
||||
|
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let mut persist_screen: Option<(String, u16, u16, u64, Vec<u8>)> = None;
|
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let sends = {
|
||||
let mut locked = state.lock().expect("server state poisoned");
|
||||
let scrollback = locked.config.scrollback;
|
||||
@@ -2255,6 +2471,27 @@ async fn broadcast_output(
|
||||
while session.recent.len() > scrollback {
|
||||
session.recent.pop_front();
|
||||
}
|
||||
// For a persistent session, mirror the screen to disk periodically so a
|
||||
// post-restart reattach repaints. Throttled by accumulated bytes to keep
|
||||
// the (atomic) write off the per-packet hot path. The actual file write
|
||||
// happens after the lock is dropped.
|
||||
if session.persistent {
|
||||
session.bytes_since_persist = session
|
||||
.bytes_since_persist
|
||||
.saturating_add(output.bytes.len());
|
||||
if session.bytes_since_persist >= SCREEN_PERSIST_BYTES {
|
||||
session.bytes_since_persist = 0;
|
||||
session.last_persisted_seq = output_seq;
|
||||
let screen = session.parser.screen();
|
||||
persist_screen = Some((
|
||||
output.session.clone(),
|
||||
screen.size().1,
|
||||
screen.size().0,
|
||||
output_seq,
|
||||
screen_snapshot(screen),
|
||||
));
|
||||
}
|
||||
}
|
||||
let mut sends = Vec::new();
|
||||
for (client_id, client) in session.clients.iter_mut() {
|
||||
client.send_seq += 1;
|
||||
@@ -2299,6 +2536,17 @@ async fn broadcast_output(
|
||||
}
|
||||
sends
|
||||
};
|
||||
if let Some((name, cols, rows, output_seq, snapshot)) = persist_screen {
|
||||
let sessions_dir = {
|
||||
let locked = state.lock().expect("server state poisoned");
|
||||
locked.sessions_dir()
|
||||
};
|
||||
if let Err(err) =
|
||||
persist::save_screen(&sessions_dir, &name, cols, rows, output_seq, &snapshot)
|
||||
{
|
||||
eprintln!("screen persist for {name} failed: {err:#}");
|
||||
}
|
||||
}
|
||||
for (endpoint, packet) in sends {
|
||||
socket.send_to(&packet, endpoint).await?;
|
||||
}
|
||||
@@ -2310,11 +2558,12 @@ async fn broadcast_session_exit(
|
||||
socket: &Arc<UdpSocket>,
|
||||
session_name: String,
|
||||
) -> Result<()> {
|
||||
let sends = {
|
||||
let (sends, persistent) = {
|
||||
let mut locked = state.lock().expect("server state poisoned");
|
||||
let Some(mut session) = locked.sessions.remove(&session_name) else {
|
||||
return Ok(());
|
||||
};
|
||||
let persistent = session.persistent;
|
||||
session.output_seq += 1;
|
||||
let output_seq = session.output_seq;
|
||||
let mut sends = Vec::new();
|
||||
@@ -2340,8 +2589,17 @@ async fn broadcast_session_exit(
|
||||
)?;
|
||||
sends.push((client.endpoint, packet));
|
||||
}
|
||||
sends
|
||||
(sends, persistent)
|
||||
};
|
||||
if persistent {
|
||||
// The shell exited; its holder cleans up its own runtime dir on the same
|
||||
// event, but remove ours too so a re-adopt scan never sees a dead entry.
|
||||
let sessions_dir = {
|
||||
let locked = state.lock().expect("server state poisoned");
|
||||
locked.sessions_dir()
|
||||
};
|
||||
persist::remove_runtime_dir(&sessions_dir, &session_name);
|
||||
}
|
||||
for (endpoint, packet) in sends {
|
||||
socket.send_to(&packet, endpoint).await?;
|
||||
}
|
||||
@@ -2487,10 +2745,56 @@ async fn maybe_rekey_clients(
|
||||
Ok(())
|
||||
}
|
||||
|
||||
/// Mirror every persistent session's current screen to disk if it changed since
|
||||
/// the last mirror. Runs on a slow timer so a crash loses at most a couple of
|
||||
/// seconds of screen state even for a low-throughput interactive session that
|
||||
/// never crosses the per-packet byte threshold. Screen bytes are captured under
|
||||
/// the lock; the (atomic) file writes happen after it is released.
|
||||
fn flush_persistent_screens(state: &Arc<Mutex<ServerState>>) {
|
||||
let (sessions_dir, to_write) = {
|
||||
let mut locked = state.lock().expect("server state poisoned");
|
||||
if !locked.config.persist_sessions {
|
||||
return;
|
||||
}
|
||||
let sessions_dir = locked.sessions_dir();
|
||||
let mut to_write: Vec<(String, u16, u16, u64, Vec<u8>)> = Vec::new();
|
||||
for (name, session) in locked.sessions.iter_mut() {
|
||||
if !session.persistent || session.output_seq == session.last_persisted_seq {
|
||||
continue;
|
||||
}
|
||||
session.last_persisted_seq = session.output_seq;
|
||||
session.bytes_since_persist = 0;
|
||||
let screen = session.parser.screen();
|
||||
to_write.push((
|
||||
name.clone(),
|
||||
screen.size().1,
|
||||
screen.size().0,
|
||||
session.output_seq,
|
||||
screen_snapshot(screen),
|
||||
));
|
||||
}
|
||||
(sessions_dir, to_write)
|
||||
};
|
||||
for (name, cols, rows, output_seq, snapshot) in to_write {
|
||||
if let Err(err) =
|
||||
persist::save_screen(&sessions_dir, &name, cols, rows, output_seq, &snapshot)
|
||||
{
|
||||
eprintln!("screen flush for {name} failed: {err:#}");
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
fn cleanup_disconnected_clients(state: &Arc<Mutex<ServerState>>) {
|
||||
// Sessions removed here are dropped after the lock is released so their
|
||||
// shells are killed (PtyHandle::drop) without holding up the event loop.
|
||||
let reaped: Vec<Session> = {
|
||||
// For a persistent session, dropping the handle only DETACHES (the shell
|
||||
// lives in the holder), so we also tell the holder to shut down — otherwise
|
||||
// a truly-abandoned shell would linger forever.
|
||||
let sessions_dir = {
|
||||
let locked = state.lock().expect("server state poisoned");
|
||||
locked.sessions_dir()
|
||||
};
|
||||
let reaped: Vec<(String, Session)> = {
|
||||
let mut locked = state.lock().expect("server state poisoned");
|
||||
let timeout = Duration::from_secs(locked.config.client_timeout_secs.max(1));
|
||||
let now = Instant::now();
|
||||
@@ -2540,10 +2844,17 @@ fn cleanup_disconnected_clients(state: &Arc<Mutex<ServerState>>) {
|
||||
.collect();
|
||||
to_reap
|
||||
.into_iter()
|
||||
.filter_map(|name| locked.sessions.remove(&name))
|
||||
.filter_map(|name| locked.sessions.remove(&name).map(|session| (name, session)))
|
||||
.collect()
|
||||
};
|
||||
drop(reaped);
|
||||
for (name, mut session) in reaped {
|
||||
if session.persistent {
|
||||
// Ask the holder to terminate the shell and exit, then clean its
|
||||
// runtime dir, so the abandoned shell does not survive forever.
|
||||
persist::request_shutdown(&sessions_dir, &name, session.holder_control.as_mut());
|
||||
}
|
||||
drop(session);
|
||||
}
|
||||
}
|
||||
|
||||
fn find_client_key(
|
||||
@@ -2583,6 +2894,19 @@ fn parse_size(raw: &str) -> Result<(u16, u16)> {
|
||||
Ok((cols.parse()?, rows.parse()?))
|
||||
}
|
||||
|
||||
/// Parse `--env NAME=VALUE` arguments passed to the holder back into pairs. The
|
||||
/// value may itself contain `=`, so split only on the first.
|
||||
fn parse_env_pairs(raw: &[String]) -> Result<Vec<(String, String)>> {
|
||||
raw.iter()
|
||||
.map(|entry| {
|
||||
let (name, value) = entry
|
||||
.split_once('=')
|
||||
.with_context(|| format!("env entry {entry:?} must be NAME=VALUE"))?;
|
||||
Ok((name.to_string(), value.to_string()))
|
||||
})
|
||||
.collect()
|
||||
}
|
||||
|
||||
#[cfg(test)]
|
||||
mod tests {
|
||||
use super::*;
|
||||
@@ -2853,6 +3177,10 @@ mod tests {
|
||||
output_seq: 0,
|
||||
recent: VecDeque::new(),
|
||||
empty_since: None,
|
||||
holder_control: None,
|
||||
persistent: false,
|
||||
bytes_since_persist: 0,
|
||||
last_persisted_seq: 0,
|
||||
},
|
||||
);
|
||||
// Keep the O(1) conn_id index in sync, matching `insert_client`.
|
||||
|
||||
@@ -46,6 +46,14 @@ pub struct ServerConfig {
|
||||
pub allow_agent_forwarding: bool,
|
||||
#[serde(default = "default_accept_env")]
|
||||
pub accept_env: Vec<String>,
|
||||
/// Run each terminal session's shell under a small per-session *holder*
|
||||
/// process so it survives a `dosh-server` restart (crash/upgrade/
|
||||
/// `systemctl restart`). On startup the server re-adopts live holders and
|
||||
/// reattaching clients land on the same shell with screen state intact. When
|
||||
/// `false`, sessions behave exactly as before: the shell is a child of the
|
||||
/// server and dies with it.
|
||||
#[serde(default = "default_true")]
|
||||
pub persist_sessions: bool,
|
||||
}
|
||||
|
||||
impl Default for ServerConfig {
|
||||
@@ -76,6 +84,7 @@ impl Default for ServerConfig {
|
||||
allow_remote_non_loopback_bind: false,
|
||||
allow_agent_forwarding: false,
|
||||
accept_env: default_accept_env(),
|
||||
persist_sessions: true,
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
@@ -2,6 +2,7 @@ pub mod auth;
|
||||
pub mod config;
|
||||
pub mod crypto;
|
||||
pub mod native;
|
||||
pub mod persist;
|
||||
pub mod protocol;
|
||||
pub mod pty;
|
||||
pub mod ssh_agent;
|
||||
|
||||
+658
@@ -0,0 +1,658 @@
|
||||
//! Session persistence across server restarts.
|
||||
//!
|
||||
//! A persistent dosh session's shell does not run as a child of `dosh-server`.
|
||||
//! Instead the server spawns a tiny per-session *holder* process (the same
|
||||
//! `dosh-server` binary re-exec'd as `dosh-server hold ...`). The holder calls
|
||||
//! `setsid()` to leave the server's process group/session, opens a PTY, spawns
|
||||
//! the shell as ITS own child, and listens on a Unix socket in a per-session
|
||||
//! runtime directory. The server connects to that socket and the holder hands it
|
||||
//! the PTY master fd over `SCM_RIGHTS`.
|
||||
//!
|
||||
//! Because the shell belongs to the holder (which is in its own session and is
|
||||
//! not waited on by the server), killing or restarting `dosh-server` leaves the
|
||||
//! holder + shell alive. On startup the server scans the runtime directory,
|
||||
//! reconnects to each live holder, receives the master fd again, and rebuilds the
|
||||
//! in-memory session so clients reattach to the very same shell.
|
||||
//!
|
||||
//! Screen / scrollback state lives only in server memory, so it is also mirrored
|
||||
//! to disk (atomically) and restored on re-adoption, letting a reattaching client
|
||||
//! repaint the screen exactly as it was before the restart.
|
||||
|
||||
use anyhow::{Context, Result, anyhow, bail};
|
||||
use std::io::{Read, Write};
|
||||
use std::os::fd::{AsRawFd, FromRawFd, IntoRawFd, RawFd};
|
||||
use std::os::unix::net::{UnixListener, UnixStream};
|
||||
use std::path::{Path, PathBuf};
|
||||
use std::time::Duration;
|
||||
|
||||
/// One-byte commands a server sends to a holder over its control socket after
|
||||
/// the holder has handed back the master fd.
|
||||
const HOLDER_CMD_SHUTDOWN: u8 = b'X';
|
||||
|
||||
/// Magic written into a holder's `meta` file, bumped if the on-disk layout
|
||||
/// changes so a stale holder from an incompatible build is ignored.
|
||||
const META_MAGIC: &str = "dosh-holder-1";
|
||||
|
||||
/// Per-session runtime metadata persisted next to the holder socket.
|
||||
#[derive(Debug, Clone)]
|
||||
pub struct HolderMeta {
|
||||
pub session: String,
|
||||
pub shell_pid: i32,
|
||||
}
|
||||
|
||||
/// Root runtime directory holding one subdirectory per persistent session.
|
||||
/// Lives under `sessions_dir/run` so it shares the session storage location and
|
||||
/// can be wiped with it.
|
||||
pub fn runtime_root(sessions_dir: &Path) -> PathBuf {
|
||||
sessions_dir.join("run")
|
||||
}
|
||||
|
||||
/// Map a session name to a filesystem-safe directory name. Session names are
|
||||
/// user-controlled, so hex-encode them rather than trusting them as path
|
||||
/// components (avoids traversal, slashes, NULs, length issues).
|
||||
fn session_dir_name(session: &str) -> String {
|
||||
let mut out = String::with_capacity(session.len() * 2);
|
||||
for byte in session.as_bytes() {
|
||||
out.push(char::from_digit((byte >> 4) as u32, 16).unwrap());
|
||||
out.push(char::from_digit((byte & 0xf) as u32, 16).unwrap());
|
||||
}
|
||||
out
|
||||
}
|
||||
|
||||
fn decode_session_dir_name(name: &str) -> Option<String> {
|
||||
if !name.len().is_multiple_of(2) {
|
||||
return None;
|
||||
}
|
||||
let mut bytes = Vec::with_capacity(name.len() / 2);
|
||||
let raw = name.as_bytes();
|
||||
let mut i = 0;
|
||||
while i < raw.len() {
|
||||
let hi = (raw[i] as char).to_digit(16)?;
|
||||
let lo = (raw[i + 1] as char).to_digit(16)?;
|
||||
bytes.push(((hi << 4) | lo) as u8);
|
||||
i += 2;
|
||||
}
|
||||
String::from_utf8(bytes).ok()
|
||||
}
|
||||
|
||||
/// Directory for one session's holder runtime state.
|
||||
pub fn session_runtime_dir(sessions_dir: &Path, session: &str) -> PathBuf {
|
||||
runtime_root(sessions_dir).join(session_dir_name(session))
|
||||
}
|
||||
|
||||
fn holder_sock_path(dir: &Path) -> PathBuf {
|
||||
dir.join("holder.sock")
|
||||
}
|
||||
|
||||
fn meta_path(dir: &Path) -> PathBuf {
|
||||
dir.join("meta")
|
||||
}
|
||||
|
||||
fn screen_path(dir: &Path) -> PathBuf {
|
||||
dir.join("screen")
|
||||
}
|
||||
|
||||
/// Create the runtime directory tree with private (0700) permissions.
|
||||
pub fn ensure_runtime_dir(sessions_dir: &Path, session: &str) -> Result<PathBuf> {
|
||||
use std::os::unix::fs::PermissionsExt;
|
||||
let root = runtime_root(sessions_dir);
|
||||
std::fs::create_dir_all(&root).with_context(|| format!("create {}", root.display()))?;
|
||||
let _ = std::fs::set_permissions(&root, std::fs::Permissions::from_mode(0o700));
|
||||
let dir = session_runtime_dir(sessions_dir, session);
|
||||
std::fs::create_dir_all(&dir).with_context(|| format!("create {}", dir.display()))?;
|
||||
std::fs::set_permissions(&dir, std::fs::Permissions::from_mode(0o700))
|
||||
.with_context(|| format!("chmod {}", dir.display()))?;
|
||||
Ok(dir)
|
||||
}
|
||||
|
||||
/// Atomically write `data` to `path` (write temp + rename), so a concurrent
|
||||
/// reader (e.g. a restarting server) never sees a half-written file.
|
||||
fn atomic_write(path: &Path, data: &[u8]) -> Result<()> {
|
||||
use std::os::unix::fs::PermissionsExt;
|
||||
let tmp = path.with_extension("tmp");
|
||||
{
|
||||
let mut file =
|
||||
std::fs::File::create(&tmp).with_context(|| format!("create {}", tmp.display()))?;
|
||||
let _ = file.set_permissions(std::fs::Permissions::from_mode(0o600));
|
||||
file.write_all(data)
|
||||
.with_context(|| format!("write {}", tmp.display()))?;
|
||||
file.sync_all().ok();
|
||||
}
|
||||
std::fs::rename(&tmp, path)
|
||||
.with_context(|| format!("rename {} -> {}", tmp.display(), path.display()))?;
|
||||
Ok(())
|
||||
}
|
||||
|
||||
/// Persist the vt100 screen snapshot plus recent raw output for a session so a
|
||||
/// post-restart reattach repaints correctly. `snapshot` is the bytes a fresh
|
||||
/// attach would receive (alt-screen toggle + `state_formatted`).
|
||||
pub fn save_screen(
|
||||
sessions_dir: &Path,
|
||||
session: &str,
|
||||
cols: u16,
|
||||
rows: u16,
|
||||
output_seq: u64,
|
||||
snapshot: &[u8],
|
||||
) -> Result<()> {
|
||||
let dir = session_runtime_dir(sessions_dir, session);
|
||||
if !dir.exists() {
|
||||
// No holder runtime for this session (non-persistent): nothing to do.
|
||||
return Ok(());
|
||||
}
|
||||
let mut buf = Vec::with_capacity(snapshot.len() + 32);
|
||||
buf.extend_from_slice(&cols.to_be_bytes());
|
||||
buf.extend_from_slice(&rows.to_be_bytes());
|
||||
buf.extend_from_slice(&output_seq.to_be_bytes());
|
||||
buf.extend_from_slice(&(snapshot.len() as u32).to_be_bytes());
|
||||
buf.extend_from_slice(snapshot);
|
||||
atomic_write(&screen_path(&dir), &buf)
|
||||
}
|
||||
|
||||
/// A restored screen for a re-adopted session.
|
||||
pub struct SavedScreen {
|
||||
pub cols: u16,
|
||||
pub rows: u16,
|
||||
pub output_seq: u64,
|
||||
pub snapshot: Vec<u8>,
|
||||
}
|
||||
|
||||
/// Load a previously persisted screen, if any.
|
||||
pub fn load_screen(sessions_dir: &Path, session: &str) -> Option<SavedScreen> {
|
||||
let dir = session_runtime_dir(sessions_dir, session);
|
||||
let data = std::fs::read(screen_path(&dir)).ok()?;
|
||||
if data.len() < 16 {
|
||||
return None;
|
||||
}
|
||||
let cols = u16::from_be_bytes(data[0..2].try_into().ok()?);
|
||||
let rows = u16::from_be_bytes(data[2..4].try_into().ok()?);
|
||||
let output_seq = u64::from_be_bytes(data[4..12].try_into().ok()?);
|
||||
let len = u32::from_be_bytes(data[12..16].try_into().ok()?) as usize;
|
||||
if data.len() < 16 + len {
|
||||
return None;
|
||||
}
|
||||
Some(SavedScreen {
|
||||
cols,
|
||||
rows,
|
||||
output_seq,
|
||||
snapshot: data[16..16 + len].to_vec(),
|
||||
})
|
||||
}
|
||||
|
||||
fn write_meta(dir: &Path, meta: &HolderMeta) -> Result<()> {
|
||||
let body = format!("{META_MAGIC}\n{}\n{}\n", meta.shell_pid, meta.session);
|
||||
atomic_write(&meta_path(dir), body.as_bytes())
|
||||
}
|
||||
|
||||
fn read_meta(dir: &Path) -> Option<HolderMeta> {
|
||||
let body = std::fs::read_to_string(meta_path(dir)).ok()?;
|
||||
let mut lines = body.lines();
|
||||
if lines.next()? != META_MAGIC {
|
||||
return None;
|
||||
}
|
||||
let shell_pid: i32 = lines.next()?.parse().ok()?;
|
||||
let session = lines.next()?.to_string();
|
||||
Some(HolderMeta { session, shell_pid })
|
||||
}
|
||||
|
||||
/// Spawn a holder process for `session`: re-exec this binary as `dosh-server
|
||||
/// hold` with the runtime dir, shell, terminal size, and accepted env. The
|
||||
/// holder daemonizes (setsid, owns the PTY) and listens on its control socket.
|
||||
/// Returns once the holder has signalled readiness by creating its socket.
|
||||
#[allow(clippy::too_many_arguments)]
|
||||
pub fn spawn_holder(
|
||||
sessions_dir: &Path,
|
||||
session: &str,
|
||||
shell: &str,
|
||||
cols: u16,
|
||||
rows: u16,
|
||||
env: &[(String, String)],
|
||||
) -> Result<()> {
|
||||
let dir = ensure_runtime_dir(sessions_dir, session)?;
|
||||
let sock = holder_sock_path(&dir);
|
||||
// Clear any stale socket left by a crashed holder with the same name.
|
||||
let _ = std::fs::remove_file(&sock);
|
||||
|
||||
let exe = std::env::current_exe().context("locate current executable")?;
|
||||
let mut cmd = std::process::Command::new(exe);
|
||||
cmd.arg("hold")
|
||||
.arg("--runtime-dir")
|
||||
.arg(&dir)
|
||||
.arg("--session")
|
||||
.arg(session)
|
||||
.arg("--shell")
|
||||
.arg(shell)
|
||||
.arg("--cols")
|
||||
.arg(cols.to_string())
|
||||
.arg("--rows")
|
||||
.arg(rows.to_string());
|
||||
for (name, value) in env {
|
||||
cmd.arg("--env").arg(format!("{name}={value}"));
|
||||
}
|
||||
cmd.stdin(std::process::Stdio::null())
|
||||
.stdout(std::process::Stdio::null())
|
||||
.stderr(std::process::Stdio::null());
|
||||
let mut child = cmd.spawn().context("spawn holder process")?;
|
||||
|
||||
// Wait (briefly) for the holder to come up. The holder forks/setsids before
|
||||
// creating the socket; once the socket exists we can connect. We also reap
|
||||
// the short-lived launcher child so it never becomes a zombie.
|
||||
let deadline = std::time::Instant::now() + Duration::from_secs(5);
|
||||
loop {
|
||||
if sock.exists() {
|
||||
break;
|
||||
}
|
||||
if std::time::Instant::now() >= deadline {
|
||||
let _ = child.kill();
|
||||
let _ = child.wait();
|
||||
bail!("holder for session {session} did not come up in time");
|
||||
}
|
||||
std::thread::sleep(Duration::from_millis(20));
|
||||
}
|
||||
// The launcher exits immediately after the grandchild setsids; reap it.
|
||||
let _ = child.wait();
|
||||
Ok(())
|
||||
}
|
||||
|
||||
/// Connect to a session's holder and receive the PTY master fd over SCM_RIGHTS.
|
||||
/// Returns the raw fd (caller owns it) and the holder control socket, kept open
|
||||
/// so the server can later ask the holder to shut down. Returns an error if the
|
||||
/// holder is gone (caller then degrades to a fresh, non-persistent session).
|
||||
pub fn adopt_holder(sessions_dir: &Path, session: &str) -> Result<(RawFd, UnixStream)> {
|
||||
let dir = session_runtime_dir(sessions_dir, session);
|
||||
let sock = holder_sock_path(&dir);
|
||||
let mut stream = UnixStream::connect(&sock)
|
||||
.with_context(|| format!("connect holder socket {}", sock.display()))?;
|
||||
stream.set_read_timeout(Some(Duration::from_secs(5))).ok();
|
||||
let fd = recv_fd(&mut stream).context("receive master fd from holder")?;
|
||||
Ok((fd, stream))
|
||||
}
|
||||
|
||||
/// Ask a holder to terminate its shell and exit, then clean its runtime dir.
|
||||
/// Used when reaping a truly-abandoned persistent session.
|
||||
pub fn request_shutdown(sessions_dir: &Path, session: &str, control: Option<&mut UnixStream>) {
|
||||
if let Some(stream) = control {
|
||||
let _ = stream.write_all(&[HOLDER_CMD_SHUTDOWN]);
|
||||
let _ = stream.flush();
|
||||
} else {
|
||||
let dir = session_runtime_dir(sessions_dir, session);
|
||||
if let Ok(mut stream) = UnixStream::connect(holder_sock_path(&dir)) {
|
||||
// Drain the fd the holder sends on connect, then send shutdown.
|
||||
let _ = recv_fd(&mut stream);
|
||||
let _ = stream.write_all(&[HOLDER_CMD_SHUTDOWN]);
|
||||
let _ = stream.flush();
|
||||
}
|
||||
}
|
||||
// Give the holder a moment to tear down, then remove its runtime dir.
|
||||
std::thread::sleep(Duration::from_millis(50));
|
||||
let dir = session_runtime_dir(sessions_dir, session);
|
||||
let _ = std::fs::remove_dir_all(&dir);
|
||||
}
|
||||
|
||||
/// Remove a session's runtime directory unconditionally (best effort).
|
||||
pub fn remove_runtime_dir(sessions_dir: &Path, session: &str) {
|
||||
let dir = session_runtime_dir(sessions_dir, session);
|
||||
let _ = std::fs::remove_dir_all(&dir);
|
||||
}
|
||||
|
||||
/// Scan the runtime root for holders left behind by a previous server. Returns
|
||||
/// `(session_name, meta)` for each one whose holder process still appears alive.
|
||||
/// Stale entries (no live process) are cleaned up.
|
||||
pub fn scan_existing_holders(sessions_dir: &Path) -> Vec<HolderMeta> {
|
||||
let root = runtime_root(sessions_dir);
|
||||
let mut found = Vec::new();
|
||||
let Ok(entries) = std::fs::read_dir(&root) else {
|
||||
return found;
|
||||
};
|
||||
for entry in entries.flatten() {
|
||||
let dir = entry.path();
|
||||
if !dir.is_dir() {
|
||||
continue;
|
||||
}
|
||||
let Some(name) = dir.file_name().and_then(|n| n.to_str()) else {
|
||||
continue;
|
||||
};
|
||||
// Decode the on-disk name back to a session name; skip junk dirs.
|
||||
if decode_session_dir_name(name).is_none() {
|
||||
continue;
|
||||
}
|
||||
match read_meta(&dir) {
|
||||
Some(meta) if process_alive(meta.shell_pid) && holder_sock_path(&dir).exists() => {
|
||||
found.push(meta);
|
||||
}
|
||||
_ => {
|
||||
// Holder gone or meta unreadable: clean up so we don't try to
|
||||
// adopt a dead session (degrade to fresh on next attach).
|
||||
let _ = std::fs::remove_dir_all(&dir);
|
||||
}
|
||||
}
|
||||
}
|
||||
found
|
||||
}
|
||||
|
||||
/// Whether a pid refers to a live process (signal 0 probe).
|
||||
fn process_alive(pid: i32) -> bool {
|
||||
if pid <= 0 {
|
||||
return false;
|
||||
}
|
||||
unsafe {
|
||||
libc::kill(pid, 0) == 0
|
||||
|| std::io::Error::last_os_error().raw_os_error() == Some(libc::EPERM)
|
||||
}
|
||||
}
|
||||
|
||||
// ---------------------------------------------------------------------------
|
||||
// Holder process entry point
|
||||
// ---------------------------------------------------------------------------
|
||||
|
||||
/// Run as a holder process. Daemonizes (double-fork + setsid), opens a PTY,
|
||||
/// spawns the shell as its own child, and serves the control socket: every
|
||||
/// accepted connection is handed the master fd (SCM_RIGHTS); a subsequent
|
||||
/// SHUTDOWN byte (or the shell exiting) tears everything down.
|
||||
///
|
||||
/// This function does not return on success — it `exit`s the process. Errors
|
||||
/// before the daemonization point are returned to the launcher.
|
||||
#[allow(clippy::too_many_arguments)]
|
||||
pub fn run_holder(
|
||||
runtime_dir: &Path,
|
||||
session: &str,
|
||||
shell: &str,
|
||||
cols: u16,
|
||||
rows: u16,
|
||||
env: &[(String, String)],
|
||||
) -> Result<()> {
|
||||
use portable_pty::{NativePtySystem, PtySize, PtySystem};
|
||||
|
||||
// Detach from the launching server: own session + process group so a server
|
||||
// exit (even a process-group kill of the service) does not take us down.
|
||||
daemonize().context("daemonize holder")?;
|
||||
|
||||
let pty_system = NativePtySystem::default();
|
||||
let pair = pty_system
|
||||
.openpty(PtySize {
|
||||
rows,
|
||||
cols,
|
||||
pixel_width: 0,
|
||||
pixel_height: 0,
|
||||
})
|
||||
.context("holder open pty")?;
|
||||
let cmd = crate::pty::build_shell_command(shell, env);
|
||||
let mut child = pair
|
||||
.slave
|
||||
.spawn_command(cmd)
|
||||
.context("holder spawn shell")?;
|
||||
drop(pair.slave);
|
||||
let master_fd = pair
|
||||
.master
|
||||
.as_raw_fd()
|
||||
.ok_or_else(|| anyhow!("holder master has no raw fd"))?;
|
||||
let shell_pid = child.process_id().map(|p| p as i32).unwrap_or(-1);
|
||||
|
||||
write_meta(
|
||||
runtime_dir,
|
||||
&HolderMeta {
|
||||
session: session.to_string(),
|
||||
shell_pid,
|
||||
},
|
||||
)?;
|
||||
|
||||
let sock = holder_sock_path(runtime_dir);
|
||||
let _ = std::fs::remove_file(&sock);
|
||||
let listener =
|
||||
UnixListener::bind(&sock).with_context(|| format!("holder bind {}", sock.display()))?;
|
||||
{
|
||||
use std::os::unix::fs::PermissionsExt;
|
||||
let _ = std::fs::set_permissions(&sock, std::fs::Permissions::from_mode(0o600));
|
||||
}
|
||||
listener
|
||||
.set_nonblocking(false)
|
||||
.context("holder listener blocking")?;
|
||||
|
||||
// A watcher thread reaps the shell: when it exits, the holder cleans up and
|
||||
// exits too, so an abandoned shell does not linger forever.
|
||||
let runtime_owned = runtime_dir.to_path_buf();
|
||||
std::thread::spawn(move || {
|
||||
let _ = child.wait();
|
||||
// Shell exited: remove runtime dir and exit the holder process.
|
||||
let _ = std::fs::remove_dir_all(&runtime_owned);
|
||||
std::process::exit(0);
|
||||
});
|
||||
|
||||
// Accept loop: each connecting server gets the master fd; a SHUTDOWN byte
|
||||
// from any of them tears the holder down. Multiple servers never run at once
|
||||
// in practice (one service), but serving repeated connections lets a server
|
||||
// restart re-adopt cleanly.
|
||||
for stream in listener.incoming() {
|
||||
let Ok(mut stream) = stream else { continue };
|
||||
if send_fd(&mut stream, master_fd).is_err() {
|
||||
continue;
|
||||
}
|
||||
// Wait for an optional command byte. EOF (server dropped the control
|
||||
// socket on its own exit) just means "keep running, await re-adoption".
|
||||
let mut cmd = [0u8; 1];
|
||||
match stream.read(&mut cmd) {
|
||||
Ok(1) if cmd[0] == HOLDER_CMD_SHUTDOWN => {
|
||||
let _ = std::fs::remove_dir_all(runtime_dir);
|
||||
std::process::exit(0);
|
||||
}
|
||||
_ => {
|
||||
// Server detached (exit/restart) or sent nothing actionable:
|
||||
// loop back and wait for the next server to re-adopt us.
|
||||
}
|
||||
}
|
||||
}
|
||||
Ok(())
|
||||
}
|
||||
|
||||
/// Double-fork + `setsid` so the holder runs in its own session, detached from
|
||||
/// the server's controlling terminal and process group. Without this a
|
||||
/// `systemctl restart` (which signals the whole service cgroup/process group)
|
||||
/// could take the holder down with the server.
|
||||
fn daemonize() -> Result<()> {
|
||||
// First fork: parent (launcher) returns to reap; child continues.
|
||||
match unsafe { libc::fork() } {
|
||||
-1 => bail!("fork: {}", std::io::Error::last_os_error()),
|
||||
0 => {}
|
||||
_ => {
|
||||
// Parent process: exit so the launcher's wait() returns promptly and
|
||||
// the grandchild is reparented to init.
|
||||
std::process::exit(0);
|
||||
}
|
||||
}
|
||||
// New session: detaches from controlling tty and the server's process group.
|
||||
if unsafe { libc::setsid() } == -1 {
|
||||
bail!("setsid: {}", std::io::Error::last_os_error());
|
||||
}
|
||||
// Second fork: ensures we are not a session leader, so we can never
|
||||
// re-acquire a controlling terminal.
|
||||
match unsafe { libc::fork() } {
|
||||
-1 => bail!("fork2: {}", std::io::Error::last_os_error()),
|
||||
0 => Ok(()),
|
||||
_ => std::process::exit(0),
|
||||
}
|
||||
}
|
||||
|
||||
// ---------------------------------------------------------------------------
|
||||
// SCM_RIGHTS file-descriptor passing over a Unix domain socket
|
||||
// ---------------------------------------------------------------------------
|
||||
|
||||
/// Send a single fd over `stream` using SCM_RIGHTS, with one byte of normal data
|
||||
/// (sendmsg requires at least one iovec byte for the ancillary data to ride on).
|
||||
fn send_fd(stream: &mut UnixStream, fd: RawFd) -> Result<()> {
|
||||
let dummy: [u8; 1] = [0];
|
||||
let mut iov = libc::iovec {
|
||||
iov_base: dummy.as_ptr() as *mut libc::c_void,
|
||||
iov_len: 1,
|
||||
};
|
||||
let mut cmsg_buf = [0u8; cmsg_space_one_fd()];
|
||||
let mut msg: libc::msghdr = unsafe { std::mem::zeroed() };
|
||||
msg.msg_iov = &mut iov;
|
||||
msg.msg_iovlen = 1;
|
||||
msg.msg_control = cmsg_buf.as_mut_ptr() as *mut libc::c_void;
|
||||
msg.msg_controllen = cmsg_buf.len() as _;
|
||||
|
||||
unsafe {
|
||||
let cmsg = libc::CMSG_FIRSTHDR(&msg);
|
||||
if cmsg.is_null() {
|
||||
bail!("CMSG_FIRSTHDR null");
|
||||
}
|
||||
(*cmsg).cmsg_level = libc::SOL_SOCKET;
|
||||
(*cmsg).cmsg_type = libc::SCM_RIGHTS;
|
||||
(*cmsg).cmsg_len = libc::CMSG_LEN(std::mem::size_of::<RawFd>() as u32) as _;
|
||||
std::ptr::copy_nonoverlapping(
|
||||
&fd as *const RawFd as *const u8,
|
||||
libc::CMSG_DATA(cmsg),
|
||||
std::mem::size_of::<RawFd>(),
|
||||
);
|
||||
let n = libc::sendmsg(stream.as_raw_fd(), &msg, 0);
|
||||
if n < 0 {
|
||||
return Err(std::io::Error::last_os_error()).context("sendmsg SCM_RIGHTS");
|
||||
}
|
||||
}
|
||||
Ok(())
|
||||
}
|
||||
|
||||
/// Receive a single fd sent via SCM_RIGHTS. Returns a fresh fd owned by the
|
||||
/// caller.
|
||||
fn recv_fd(stream: &mut UnixStream) -> Result<RawFd> {
|
||||
let mut dummy = [0u8; 1];
|
||||
let mut iov = libc::iovec {
|
||||
iov_base: dummy.as_mut_ptr() as *mut libc::c_void,
|
||||
iov_len: 1,
|
||||
};
|
||||
let mut cmsg_buf = [0u8; cmsg_space_one_fd()];
|
||||
let mut msg: libc::msghdr = unsafe { std::mem::zeroed() };
|
||||
msg.msg_iov = &mut iov;
|
||||
msg.msg_iovlen = 1;
|
||||
msg.msg_control = cmsg_buf.as_mut_ptr() as *mut libc::c_void;
|
||||
msg.msg_controllen = cmsg_buf.len() as _;
|
||||
|
||||
unsafe {
|
||||
let n = libc::recvmsg(stream.as_raw_fd(), &mut msg, 0);
|
||||
if n < 0 {
|
||||
return Err(std::io::Error::last_os_error()).context("recvmsg SCM_RIGHTS");
|
||||
}
|
||||
if n == 0 {
|
||||
bail!("holder closed connection before sending fd");
|
||||
}
|
||||
let cmsg = libc::CMSG_FIRSTHDR(&msg);
|
||||
if cmsg.is_null() {
|
||||
bail!("no ancillary data (fd) received from holder");
|
||||
}
|
||||
if (*cmsg).cmsg_level != libc::SOL_SOCKET || (*cmsg).cmsg_type != libc::SCM_RIGHTS {
|
||||
bail!("unexpected ancillary message from holder");
|
||||
}
|
||||
let mut fd: RawFd = -1;
|
||||
std::ptr::copy_nonoverlapping(
|
||||
libc::CMSG_DATA(cmsg),
|
||||
&mut fd as *mut RawFd as *mut u8,
|
||||
std::mem::size_of::<RawFd>(),
|
||||
);
|
||||
if fd < 0 {
|
||||
bail!("invalid fd received from holder");
|
||||
}
|
||||
Ok(fd)
|
||||
}
|
||||
}
|
||||
|
||||
/// Space, in bytes, needed for a control-message buffer carrying exactly one fd.
|
||||
const fn cmsg_space_one_fd() -> usize {
|
||||
// CMSG_SPACE is not const in libc; this is the equivalent for one RawFd.
|
||||
// cmsghdr is aligned to size_of::<usize>(); add data length rounded up.
|
||||
let data = std::mem::size_of::<RawFd>();
|
||||
let hdr = std::mem::size_of::<libc::cmsghdr>();
|
||||
let align = std::mem::size_of::<usize>();
|
||||
// round(hdr) + round(data)
|
||||
((hdr + align - 1) & !(align - 1)) + ((data + align - 1) & !(align - 1))
|
||||
}
|
||||
|
||||
/// Helper used by `adopt_holder` callers to turn the received raw fd into an
|
||||
/// owned `File`-like object if they need RAII (the server hands it to
|
||||
/// `pty::adopt_pty_from_fd`, which takes ownership of the raw fd).
|
||||
pub fn fd_into_file(fd: RawFd) -> std::fs::File {
|
||||
unsafe { std::fs::File::from_raw_fd(fd) }
|
||||
}
|
||||
|
||||
/// Convert a `File` back into a raw fd it no longer owns (so it can be handed to
|
||||
/// `adopt_pty_from_fd`). Currently unused outside tests but kept symmetric.
|
||||
pub fn file_into_fd(file: std::fs::File) -> RawFd {
|
||||
file.into_raw_fd()
|
||||
}
|
||||
|
||||
#[cfg(test)]
|
||||
mod tests {
|
||||
use super::*;
|
||||
|
||||
#[test]
|
||||
fn session_dir_name_round_trips() {
|
||||
for name in ["default", "work", "a/b/../c", "weird name", "日本語"] {
|
||||
let encoded = session_dir_name(name);
|
||||
assert!(encoded.bytes().all(|b| b.is_ascii_hexdigit()));
|
||||
assert_eq!(decode_session_dir_name(&encoded).as_deref(), Some(name));
|
||||
}
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn decode_rejects_non_hex() {
|
||||
assert!(decode_session_dir_name("zz").is_none());
|
||||
assert!(decode_session_dir_name("abc").is_none());
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn save_and_load_screen_round_trips() {
|
||||
let tmp = tempfile::tempdir().unwrap();
|
||||
let sessions_dir = tmp.path();
|
||||
ensure_runtime_dir(sessions_dir, "work").unwrap();
|
||||
let snap = b"\x1b[?1049lhello world".to_vec();
|
||||
save_screen(sessions_dir, "work", 100, 40, 7, &snap).unwrap();
|
||||
let loaded = load_screen(sessions_dir, "work").expect("screen restored");
|
||||
assert_eq!(loaded.cols, 100);
|
||||
assert_eq!(loaded.rows, 40);
|
||||
assert_eq!(loaded.output_seq, 7);
|
||||
assert_eq!(loaded.snapshot, snap);
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn load_screen_absent_is_none() {
|
||||
let tmp = tempfile::tempdir().unwrap();
|
||||
assert!(load_screen(tmp.path(), "missing").is_none());
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn scan_skips_dead_and_junk_entries() {
|
||||
let tmp = tempfile::tempdir().unwrap();
|
||||
let sessions_dir = tmp.path();
|
||||
// A meta pointing at a definitely-dead pid is cleaned up, not returned.
|
||||
let dir = ensure_runtime_dir(sessions_dir, "ghost").unwrap();
|
||||
write_meta(
|
||||
&dir,
|
||||
&HolderMeta {
|
||||
session: "ghost".to_string(),
|
||||
shell_pid: 2_000_000_000, // not a live pid
|
||||
},
|
||||
)
|
||||
.unwrap();
|
||||
// A junk (non-hex) directory is ignored.
|
||||
std::fs::create_dir_all(runtime_root(sessions_dir).join("not-hex")).unwrap();
|
||||
let found = scan_existing_holders(sessions_dir);
|
||||
assert!(found.is_empty(), "dead/junk holders must be skipped");
|
||||
assert!(!dir.exists(), "dead holder dir should be cleaned up");
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn send_and_recv_fd_round_trips() {
|
||||
use std::io::Seek;
|
||||
// Pass a temp file's fd across a socketpair and confirm both ends point
|
||||
// at the same open file (write via one, read via the other).
|
||||
let (mut a, mut b) = UnixStream::pair().unwrap();
|
||||
let mut file = tempfile::tempfile().unwrap();
|
||||
writeln!(file, "shared-fd-marker").unwrap();
|
||||
file.flush().unwrap();
|
||||
send_fd(&mut a, file.as_raw_fd()).unwrap();
|
||||
let received = recv_fd(&mut b).unwrap();
|
||||
let mut got = fd_into_file(received);
|
||||
got.rewind().unwrap();
|
||||
let mut contents = String::new();
|
||||
got.read_to_string(&mut contents).unwrap();
|
||||
assert!(contents.contains("shared-fd-marker"));
|
||||
}
|
||||
}
|
||||
+119
-18
@@ -1,15 +1,36 @@
|
||||
use anyhow::{Context, Result};
|
||||
use portable_pty::{Child, CommandBuilder, MasterPty, NativePtySystem, PtySize, PtySystem};
|
||||
use std::io::{Read, Write};
|
||||
use std::os::unix::io::{AsRawFd, FromRawFd, RawFd};
|
||||
use std::path::Path;
|
||||
use std::sync::{Arc, Mutex};
|
||||
use std::thread;
|
||||
use tokio::sync::mpsc;
|
||||
|
||||
pub struct PtyHandle {
|
||||
writer: Arc<Mutex<Box<dyn Write + Send>>>,
|
||||
/// Backing for a PTY master held by the server.
|
||||
///
|
||||
/// `Owned` means this process spawned the shell as a child and is responsible
|
||||
/// for it: dropping the handle kills the shell. This is the original,
|
||||
/// non-persistent model and stays the default.
|
||||
///
|
||||
/// `Adopted` means the shell lives in a separate holder process and this handle
|
||||
/// only borrows the master fd (received over a Unix socket via SCM_RIGHTS).
|
||||
/// Dropping it must NOT kill the shell — it just closes our copy of the fd and
|
||||
/// stops the reader thread, leaving the holder + shell alive so a server restart
|
||||
/// can re-adopt them.
|
||||
enum Backing {
|
||||
Owned {
|
||||
child: Mutex<Box<dyn Child + Send + Sync>>,
|
||||
_master: Box<dyn MasterPty + Send>,
|
||||
},
|
||||
Adopted {
|
||||
master: Mutex<std::fs::File>,
|
||||
},
|
||||
}
|
||||
|
||||
pub struct PtyHandle {
|
||||
writer: Arc<Mutex<Box<dyn Write + Send>>>,
|
||||
backing: Backing,
|
||||
}
|
||||
|
||||
impl PtyHandle {
|
||||
@@ -21,23 +42,40 @@ impl PtyHandle {
|
||||
}
|
||||
|
||||
pub fn resize(&self, cols: u16, rows: u16) -> Result<()> {
|
||||
self._master.resize(PtySize {
|
||||
match &self.backing {
|
||||
Backing::Owned { _master, .. } => {
|
||||
_master.resize(PtySize {
|
||||
rows,
|
||||
cols,
|
||||
pixel_width: 0,
|
||||
pixel_height: 0,
|
||||
})?;
|
||||
}
|
||||
Backing::Adopted { master } => {
|
||||
let file = master.lock().expect("pty master poisoned");
|
||||
resize_fd(file.as_raw_fd(), cols, rows)?;
|
||||
}
|
||||
}
|
||||
Ok(())
|
||||
}
|
||||
|
||||
/// True for a handle backed by a separate holder process. Such a handle must
|
||||
/// be detached (not killed) when the server lets go of a session, so the
|
||||
/// shell survives a server restart.
|
||||
pub fn is_persistent(&self) -> bool {
|
||||
matches!(self.backing, Backing::Adopted { .. })
|
||||
}
|
||||
|
||||
/// Terminate the shell process backing this PTY and reap it.
|
||||
///
|
||||
/// Without this the child shell outlives the session: dropping the master
|
||||
/// alone is not guaranteed to take the process down, and the `Child` handle
|
||||
/// used to be discarded at spawn time, which leaked one shell per
|
||||
/// abandoned session.
|
||||
/// Only meaningful for an `Owned` backing (the server spawned the shell as a
|
||||
/// child). For an `Adopted` backing the shell belongs to the holder process,
|
||||
/// so this is a no-op here; reaping a persistent session is done by asking
|
||||
/// the holder to shut down (see `persist::request_shutdown`).
|
||||
pub fn kill(&self) {
|
||||
if let Ok(mut child) = self.child.lock() {
|
||||
if let Backing::Owned { child, .. } = &self.backing
|
||||
&& let Ok(mut child) = child.lock()
|
||||
{
|
||||
let _ = child.kill();
|
||||
let _ = child.wait();
|
||||
}
|
||||
@@ -46,8 +84,27 @@ impl PtyHandle {
|
||||
|
||||
impl Drop for PtyHandle {
|
||||
fn drop(&mut self) {
|
||||
// Adopted handles must NOT kill the shell: it lives in the holder so it
|
||||
// can outlive this server. Dropping just closes our fd / stops the
|
||||
// reader. Owned handles keep the original kill-on-drop behavior.
|
||||
if let Backing::Owned { .. } = &self.backing {
|
||||
self.kill();
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
fn resize_fd(fd: RawFd, cols: u16, rows: u16) -> Result<()> {
|
||||
let winsize = libc::winsize {
|
||||
ws_row: rows,
|
||||
ws_col: cols,
|
||||
ws_xpixel: 0,
|
||||
ws_ypixel: 0,
|
||||
};
|
||||
let rc = unsafe { libc::ioctl(fd, libc::TIOCSWINSZ, &winsize) };
|
||||
if rc != 0 {
|
||||
return Err(std::io::Error::last_os_error()).context("TIOCSWINSZ");
|
||||
}
|
||||
Ok(())
|
||||
}
|
||||
|
||||
#[derive(Debug)]
|
||||
@@ -74,6 +131,27 @@ pub fn spawn_pty_session(
|
||||
pixel_height: 0,
|
||||
})
|
||||
.context("open pty")?;
|
||||
let cmd = build_shell_command(shell, env);
|
||||
let child = pair.slave.spawn_command(cmd).context("spawn shell")?;
|
||||
drop(pair.slave);
|
||||
|
||||
let writer = pair.master.take_writer().context("take pty writer")?;
|
||||
let reader = pair.master.try_clone_reader().context("clone pty reader")?;
|
||||
spawn_reader_thread(session, reader, tx)?;
|
||||
|
||||
Ok(PtyHandle {
|
||||
writer: Arc::new(Mutex::new(writer)),
|
||||
backing: Backing::Owned {
|
||||
child: Mutex::new(child),
|
||||
_master: pair.master,
|
||||
},
|
||||
})
|
||||
}
|
||||
|
||||
/// Build the [`CommandBuilder`] for a dosh shell, identically for the in-process
|
||||
/// `spawn_pty_session` and the out-of-process holder, so a persistent session's
|
||||
/// environment matches a non-persistent one.
|
||||
pub fn build_shell_command(shell: &str, env: &[(String, String)]) -> CommandBuilder {
|
||||
let mut cmd = CommandBuilder::new(shell);
|
||||
cmd.env("TERM", "xterm-256color");
|
||||
cmd.env("COLORTERM", "truecolor");
|
||||
@@ -88,11 +166,39 @@ pub fn spawn_pty_session(
|
||||
} else if let Some(parent) = Path::new(shell).parent() {
|
||||
cmd.env("PWD", parent.as_os_str());
|
||||
}
|
||||
let child = pair.slave.spawn_command(cmd).context("spawn shell")?;
|
||||
drop(pair.slave);
|
||||
cmd
|
||||
}
|
||||
|
||||
let writer = pair.master.take_writer().context("take pty writer")?;
|
||||
let mut reader = pair.master.try_clone_reader().context("clone pty reader")?;
|
||||
/// Build a [`PtyHandle`] from a master fd received from a holder process.
|
||||
///
|
||||
/// `master_fd` is an fd this handle takes ownership of (it is wrapped in a
|
||||
/// `File` and closed on drop). The shell is NOT a child of this process; it
|
||||
/// belongs to the holder, so dropping this handle leaves it running.
|
||||
pub fn adopt_pty_from_fd(
|
||||
session: String,
|
||||
master_fd: RawFd,
|
||||
tx: mpsc::UnboundedSender<PtyOutput>,
|
||||
) -> Result<PtyHandle> {
|
||||
// Take ownership of the fd. A clone gives us an independent reader so the
|
||||
// reader thread and the writer/resize side hold separate `File`s and don't
|
||||
// get closed out from under each other.
|
||||
let master = unsafe { std::fs::File::from_raw_fd(master_fd) };
|
||||
let reader_file = master.try_clone().context("clone master for reader")?;
|
||||
let writer_file = master.try_clone().context("clone master for writer")?;
|
||||
spawn_reader_thread(session, Box::new(reader_file), tx)?;
|
||||
Ok(PtyHandle {
|
||||
writer: Arc::new(Mutex::new(Box::new(writer_file))),
|
||||
backing: Backing::Adopted {
|
||||
master: Mutex::new(master),
|
||||
},
|
||||
})
|
||||
}
|
||||
|
||||
fn spawn_reader_thread(
|
||||
session: String,
|
||||
mut reader: Box<dyn Read + Send>,
|
||||
tx: mpsc::UnboundedSender<PtyOutput>,
|
||||
) -> Result<()> {
|
||||
let reader_session = session.clone();
|
||||
thread::Builder::new()
|
||||
.name(format!("dosh-pty-{session}"))
|
||||
@@ -127,10 +233,5 @@ pub fn spawn_pty_session(
|
||||
}
|
||||
})
|
||||
.context("spawn pty reader")?;
|
||||
|
||||
Ok(PtyHandle {
|
||||
writer: Arc::new(Mutex::new(writer)),
|
||||
child: Mutex::new(child),
|
||||
_master: pair.master,
|
||||
})
|
||||
Ok(())
|
||||
}
|
||||
|
||||
@@ -67,6 +67,7 @@ sessions_dir = "{sessions}"
|
||||
secret_path = "{secret}"
|
||||
host_key = "{host_key}"
|
||||
authorized_keys = ["{authorized_keys}"]
|
||||
persist_sessions = false
|
||||
"#,
|
||||
sessions = dir.path().join("sessions").display(),
|
||||
secret = dir.path().join("secret").display(),
|
||||
|
||||
@@ -83,6 +83,7 @@ sessions_dir = "{sessions}"
|
||||
secret_path = "{secret}"
|
||||
host_key = "{host_key}"
|
||||
authorized_keys = ["{authorized_keys}"]
|
||||
persist_sessions = false
|
||||
"#,
|
||||
sessions = dir.path().join("sessions").display(),
|
||||
secret = dir.path().join("secret").display(),
|
||||
@@ -1800,3 +1801,185 @@ fn native_agent_forwarding_requires_client_opt_in() {
|
||||
"agent proxy dir {agent_dir:?} must not exist without client -A opt-in"
|
||||
);
|
||||
}
|
||||
|
||||
// ---------------------------------------------------------------------------
|
||||
// Session persistence across a server restart.
|
||||
// ---------------------------------------------------------------------------
|
||||
|
||||
/// Write a server config with `persist_sessions = true` so each session's shell
|
||||
/// runs in a detached holder that survives a server restart.
|
||||
fn write_persistent_server_config(dir: &tempfile::TempDir, port: u16) -> std::path::PathBuf {
|
||||
let config = write_server_config(dir, port);
|
||||
let mut raw = fs::read_to_string(&config).unwrap();
|
||||
// The base writer hardcodes `persist_sessions = false`; flip it on.
|
||||
raw = raw.replace("persist_sessions = false", "persist_sessions = true");
|
||||
fs::write(&config, raw).unwrap();
|
||||
config
|
||||
}
|
||||
|
||||
/// Mirror the server's hex encoding of a session name to its runtime dir.
|
||||
fn session_runtime_dir(sessions_dir: &Path, session: &str) -> PathBuf {
|
||||
let mut hex = String::new();
|
||||
for b in session.as_bytes() {
|
||||
hex.push_str(&format!("{b:02x}"));
|
||||
}
|
||||
sessions_dir.join("run").join(hex)
|
||||
}
|
||||
|
||||
/// Read a holder's recorded shell pid from its meta file, if present.
|
||||
fn holder_shell_pid(sessions_dir: &Path, session: &str) -> Option<i32> {
|
||||
let meta = session_runtime_dir(sessions_dir, session).join("meta");
|
||||
let body = fs::read_to_string(meta).ok()?;
|
||||
body.lines().nth(1)?.parse().ok()
|
||||
}
|
||||
|
||||
/// Tear down a persistent session's holder + shell so a test never leaks them
|
||||
/// (the TempDir drop would otherwise leave detached processes running).
|
||||
fn kill_holder(sessions_dir: &Path, session: &str) {
|
||||
if let Some(pid) = holder_shell_pid(sessions_dir, session) {
|
||||
let _ = Command::new("kill").arg("-9").arg(pid.to_string()).status();
|
||||
}
|
||||
// Best-effort: also kill any matching holder process for this runtime dir.
|
||||
let dir = session_runtime_dir(sessions_dir, session);
|
||||
let _ = Command::new("pkill")
|
||||
.arg("-9")
|
||||
.arg("-f")
|
||||
.arg(format!("dosh-server hold --runtime-dir {}", dir.display()))
|
||||
.status();
|
||||
}
|
||||
|
||||
/// Send one encrypted Input line and give the shell a moment to act.
|
||||
fn type_line(socket: &UdpSocket, port: u16, ok: &AttachOk, key: &[u8; 32], seq: u64, line: &str) {
|
||||
let input = Input {
|
||||
bytes: line.as_bytes().to_vec(),
|
||||
};
|
||||
send_encrypted(
|
||||
socket,
|
||||
port,
|
||||
PacketKind::Input,
|
||||
ok.client_id,
|
||||
seq,
|
||||
0,
|
||||
key,
|
||||
&protocol::to_body(&input).unwrap(),
|
||||
);
|
||||
thread::sleep(Duration::from_millis(150));
|
||||
}
|
||||
|
||||
/// Proof of survival: a session's shell + state + screen outlive a full
|
||||
/// `dosh-server` process restart.
|
||||
///
|
||||
/// We attach, set durable shell state (`cd /tmp`, `export MARK=...`) and paint a
|
||||
/// recognizable marker on the screen, wait for the screen to be mirrored to disk,
|
||||
/// then KILL the server process (simulating a crash/upgrade). We restart the
|
||||
/// server on the same config/sockets, reattach, and assert we land on the SAME
|
||||
/// shell — the exported variable and working directory are still there, and the
|
||||
/// restored attach snapshot still shows the pre-restart screen — not a fresh
|
||||
/// shell.
|
||||
#[test]
|
||||
fn session_survives_server_restart_same_shell_and_screen() {
|
||||
let dir = tempfile::tempdir().unwrap();
|
||||
let sessions_dir = dir.path().join("sessions");
|
||||
let port = free_udp_port();
|
||||
let config = write_persistent_server_config(&dir, port);
|
||||
|
||||
let mut server = start_server(&dir, &config);
|
||||
|
||||
// First attach: establish durable shell state and a screen marker.
|
||||
let (socket, bootstrap, ok) = direct_attach(&config, port, "read-write");
|
||||
let key = bootstrap.session_key;
|
||||
type_line(&socket, port, &ok, &key, 2, "cd /tmp\n");
|
||||
type_line(
|
||||
&socket,
|
||||
port,
|
||||
&ok,
|
||||
&key,
|
||||
3,
|
||||
"export MARK=zebra_persist_42\n",
|
||||
);
|
||||
// Paint a unique, stable marker into the screen (printf, no trailing newline
|
||||
// scroll surprises) so the restored snapshot is easy to recognize.
|
||||
type_line(
|
||||
&socket,
|
||||
port,
|
||||
&ok,
|
||||
&key,
|
||||
4,
|
||||
"printf 'PRE_RESTART_SCREEN_MARKER\\n'\n",
|
||||
);
|
||||
// Drain output so the parser/screen state and disk mirror catch up.
|
||||
let pre = collect_frame_text(&socket, &key, 1500);
|
||||
assert!(
|
||||
pre.contains("PRE_RESTART_SCREEN_MARKER"),
|
||||
"expected to see the screen marker before restart, got {pre:?}"
|
||||
);
|
||||
// The periodic flush mirrors the screen every ~2s; wait long enough that the
|
||||
// pre-restart screen is guaranteed on disk before we crash the server.
|
||||
thread::sleep(Duration::from_secs(3));
|
||||
|
||||
let shell_pid_before = holder_shell_pid(&sessions_dir, "default");
|
||||
assert!(
|
||||
shell_pid_before.is_some(),
|
||||
"a holder shell pid should be recorded for a persistent session"
|
||||
);
|
||||
|
||||
// CRASH: kill the server process outright (its in-memory state is lost; only
|
||||
// the holder + shell + on-disk screen remain).
|
||||
let _ = server.kill();
|
||||
let _ = server.wait();
|
||||
thread::sleep(Duration::from_millis(300));
|
||||
|
||||
// The holder + shell must still be alive after the server died.
|
||||
let pid = shell_pid_before.unwrap();
|
||||
let alive = unsafe { libc::kill(pid, 0) } == 0;
|
||||
assert!(
|
||||
alive,
|
||||
"shell pid {pid} must survive the server crash (holder keeps it alive)"
|
||||
);
|
||||
|
||||
// RESTART on the same config/sockets; the server re-adopts the holder.
|
||||
let mut server = start_server(&dir, &config);
|
||||
|
||||
// Reattach. A fresh bootstrap attach lands on the EXISTING re-adopted
|
||||
// session (same name), not a new shell.
|
||||
let (socket2, bootstrap2, ok2) = direct_attach(&config, port, "read-write");
|
||||
let key2 = bootstrap2.session_key;
|
||||
|
||||
// 1) Screen survived: the restored attach snapshot still shows the marker.
|
||||
let snapshot = String::from_utf8_lossy(&ok2.snapshot).to_string();
|
||||
|
||||
// 2) Shell identity + state survived: ask the SAME shell for its state.
|
||||
type_line(
|
||||
&socket2,
|
||||
port,
|
||||
&ok2,
|
||||
&key2,
|
||||
2,
|
||||
"printf 'MARK=%s PWD=%s\\n' \"$MARK\" \"$PWD\"\n",
|
||||
);
|
||||
let post = collect_frame_text(&socket2, &key2, 2000);
|
||||
|
||||
let shell_pid_after = holder_shell_pid(&sessions_dir, "default");
|
||||
|
||||
// Clean up BEFORE asserting so a failed assert never leaks the holder.
|
||||
let _ = server.kill();
|
||||
let _ = server.wait();
|
||||
kill_holder(&sessions_dir, "default");
|
||||
|
||||
assert_eq!(
|
||||
shell_pid_after, shell_pid_before,
|
||||
"re-adopted session must be backed by the same shell pid, not a fresh one"
|
||||
);
|
||||
assert!(
|
||||
post.contains("MARK=zebra_persist_42"),
|
||||
"exported variable must survive the restart (same shell), got {post:?}"
|
||||
);
|
||||
assert!(
|
||||
post.contains("PWD=/tmp"),
|
||||
"working directory must survive the restart (same shell), got {post:?}"
|
||||
);
|
||||
assert!(
|
||||
snapshot.contains("PRE_RESTART_SCREEN_MARKER"),
|
||||
"restored attach snapshot must repaint the pre-restart screen, got {snapshot:?}"
|
||||
);
|
||||
}
|
||||
|
||||
Reference in New Issue
Block a user