Add trace command for reconnect debugging

Cargo.lock

@@ -436,7 +436,7 @@ dependencies = [
 
 [[package]]
 name = "dosh"
-version = "1.0.0-rc29"
+version = "1.0.0-rc30"
 dependencies = [
  "anyhow",
  "base64",

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "dosh"
-version = "1.0.0-rc29"
+version = "1.0.0-rc30"
 edition = "2024"
 license = "MIT"
 

README.md

@@ -73,12 +73,18 @@ File copy must be enabled by the server config.
 For terminal/reconnect bugs, run a client with:
 
 ```sh
-DOSH_TRACE=/tmp/dosh-client.log DOSH_TRACE_BYTES=1 dosh HOST
+dosh trace HOST
+```
+
+The client log path is printed before the session starts. To choose it:
+
+```sh
+dosh trace --client-log /tmp/dosh-client.log HOST
 ```
 
 Set `DOSH_TRACE=/tmp/dosh-server.log` on `dosh-server` for matching server
-events. `DOSH_TRACE_BYTES=1` records byte prefixes, so use it only for short
-reproductions.
+events. Trace byte prefixes are enabled for `dosh trace`, so use it only for
+short reproductions.
 
 ## VS Code
 

src/bin/dosh-client.rs

@@ -56,7 +56,7 @@ use std::path::{Path, PathBuf};
 use std::process::{Child, Command, Stdio};
 use std::sync::Arc;
 use std::sync::atomic::{AtomicU64, Ordering};
-use std::time::{Duration, Instant};
+use std::time::{Duration, Instant, SystemTime, UNIX_EPOCH};
 use tokio::io::{AsyncReadExt, AsyncWriteExt};
 #[cfg(unix)]
 use tokio::net::UnixStream;
@@ -265,6 +265,9 @@ async fn main() -> Result<()> {
     if args.server.as_deref() == Some("update") {
         return run_update(&config, parse_update_options(&args.command)?);
     }
+    if args.server.as_deref() == Some("trace") {
+        return run_trace_command(&args);
+    }
     if args.server.as_deref() == Some("setup") {
         return run_setup_command(&config, &args).await;
     }
@@ -776,6 +779,224 @@ async fn run_selftest_command(config: &dosh::config::ClientConfig, args: &Args)
     Ok(())
 }
 
+#[derive(Debug, Clone, PartialEq, Eq)]
+struct TraceOptions {
+    host: String,
+    command: Vec<String>,
+    client_log: PathBuf,
+    bytes: bool,
+}
+
+fn parse_trace_options(command: &[String]) -> Result<TraceOptions> {
+    let mut client_log: Option<PathBuf> = None;
+    let mut bytes = true;
+    let mut index = 0usize;
+    while index < command.len() {
+        let arg = &command[index];
+        match arg.as_str() {
+            "--bytes" => {
+                bytes = true;
+                index += 1;
+            }
+            "--no-bytes" => {
+                bytes = false;
+                index += 1;
+            }
+            "--client-log" => {
+                let path = command.get(index + 1).ok_or_else(|| {
+                    anyhow!(
+                        "usage: dosh trace [--client-log PATH] [--no-bytes] <host> [command...]"
+                    )
+                })?;
+                client_log = Some(expand_tilde(path));
+                index += 2;
+            }
+            "--" => {
+                index += 1;
+                break;
+            }
+            value if value.starts_with("--client-log=") => {
+                let path = value
+                    .strip_prefix("--client-log=")
+                    .filter(|value| !value.is_empty())
+                    .ok_or_else(|| anyhow!("--client-log requires a path"))?;
+                client_log = Some(expand_tilde(path));
+                index += 1;
+            }
+            value if value.starts_with('-') => {
+                return Err(anyhow!(
+                    "usage: dosh trace [--client-log PATH] [--no-bytes] <host> [command...] (unknown option {value})"
+                ));
+            }
+            _ => break,
+        }
+    }
+    let host = command.get(index).cloned().ok_or_else(|| {
+        anyhow!("usage: dosh trace [--client-log PATH] [--no-bytes] <host> [command...]")
+    })?;
+    let mut command_start = index + 1;
+    if command
+        .get(command_start)
+        .is_some_and(|value| value == "--")
+    {
+        command_start += 1;
+    }
+    let command = command[command_start..].to_vec();
+    let client_log = client_log.unwrap_or_else(|| default_client_trace_path(&host));
+    Ok(TraceOptions {
+        host,
+        command,
+        client_log,
+        bytes,
+    })
+}
+
+fn default_client_trace_path(host: &str) -> PathBuf {
+    let root = dirs::cache_dir()
+        .unwrap_or_else(|| expand_tilde("~/.cache"))
+        .join("dosh")
+        .join("trace");
+    let now = SystemTime::now()
+        .duration_since(UNIX_EPOCH)
+        .map(|duration| duration.as_secs())
+        .unwrap_or(0);
+    root.join(format!(
+        "client-{}-{}-{}.log",
+        sanitize_trace_name(host),
+        now,
+        std::process::id()
+    ))
+}
+
+fn sanitize_trace_name(value: &str) -> String {
+    let mut out = String::with_capacity(value.len());
+    for byte in value.bytes() {
+        if byte.is_ascii_alphanumeric() || matches!(byte, b'.' | b'-' | b'_') {
+            out.push(byte as char);
+        } else {
+            out.push('_');
+        }
+    }
+    if out.is_empty() {
+        "host".to_string()
+    } else {
+        out
+    }
+}
+
+fn run_trace_command(args: &Args) -> Result<()> {
+    let options = parse_trace_options(&args.command)?;
+    if let Some(parent) = options.client_log.parent() {
+        fs::create_dir_all(parent)
+            .with_context(|| format!("create trace log directory {}", parent.to_string_lossy()))?;
+    }
+    let exe = std::env::current_exe().context("locate current dosh executable")?;
+    println!("Dosh trace client log: {}", options.client_log.display());
+    println!("Dosh trace server log: /tmp/dosh-server.log");
+    if options.bytes {
+        println!("Dosh trace byte prefixes: enabled");
+    } else {
+        println!("Dosh trace byte prefixes: disabled");
+    }
+    let mut child = Command::new(exe);
+    push_trace_passthrough_args(&mut child, args);
+    child.arg(&options.host);
+    if !options.command.is_empty() {
+        child.arg("--");
+        child.args(&options.command);
+    }
+    child.env("DOSH_TRACE", &options.client_log);
+    child.env("DOSH_TRACE_BYTES", if options.bytes { "1" } else { "0" });
+    let status = child
+        .stdin(Stdio::inherit())
+        .stdout(Stdio::inherit())
+        .stderr(Stdio::inherit())
+        .status()
+        .context("run traced dosh client")?;
+    if !status.success() {
+        return Err(anyhow!("traced dosh exited with status {status}"));
+    }
+    Ok(())
+}
+
+fn push_trace_passthrough_args(command: &mut Command, args: &Args) {
+    if let Some(session) = &args.session {
+        command.arg("--session").arg(session);
+    }
+    if args.new {
+        command.arg("--new");
+    }
+    if args.view_only {
+        command.arg("--view-only");
+    }
+    if args.local_auth {
+        command.arg("--local-auth");
+    }
+    if let Some(auth) = &args.auth {
+        command.arg("--auth").arg(auth);
+    }
+    if args.no_cache {
+        command.arg("--no-cache");
+    }
+    for forward in &args.local_forward {
+        command.arg("-L").arg(forward);
+    }
+    for forward in &args.remote_forward {
+        command.arg("-R").arg(forward);
+    }
+    for forward in &args.dynamic_forward {
+        command.arg("-D").arg(forward);
+    }
+    if args.forward_agent {
+        command.arg("-A");
+    }
+    if args.forward_only {
+        command.arg("-N");
+    }
+    if args.background {
+        command.arg("-f");
+    }
+    if args.predict {
+        command.arg("--predict");
+    }
+    if let Some(mode) = &args.predict_mode {
+        command.arg("--predict-mode").arg(mode);
+    }
+    if args.predict_always {
+        command.arg("--predict-always");
+    }
+    if args.predict_never {
+        command.arg("--predict-never");
+    }
+    if let Some(escape_key) = &args.escape_key {
+        command.arg("--escape-key").arg(escape_key);
+    }
+    if let Some(port) = args.ssh_port {
+        command.arg("--ssh-port").arg(port.to_string());
+    }
+    if let Some(auth_command) = &args.ssh_auth_command {
+        command.arg("--ssh-auth-command").arg(auth_command);
+    }
+    if let Some(path) = &args.ssh_key {
+        command.arg("--ssh-key").arg(path);
+    }
+    if let Some(path) = &args.ssh_known_hosts {
+        command.arg("--ssh-known-hosts").arg(path);
+    }
+    if let Some(path) = &args.ssh_control_path {
+        command.arg("--ssh-control-path").arg(path);
+    }
+    if let Some(port) = args.dosh_port {
+        command.arg("--dosh-port").arg(port.to_string());
+    }
+    if let Some(host) = &args.dosh_host {
+        command.arg("--dosh-host").arg(host);
+    }
+    for _ in 0..args.verbose {
+        command.arg("-v");
+    }
+}
+
 async fn run_doctor_command(config: &dosh::config::ClientConfig, args: &Args) -> Result<()> {
     let requested = args
         .command
@@ -8280,11 +8501,12 @@ mod tests {
         input_matches_escape, is_local_status_target, is_resume_response_for_client,
         latest_release_download_url, load_first_native_identity_with_prompt,
         native_proxy_udp_warning, parse_dynamic_forward, parse_escape_key, parse_local_forward,
-        parse_remote_forward, parse_ssh_config, parse_update_options, post_submit_hold_duration,
-        queue_pending_user_input, raw_contains_host_table, recv_response_until, refresh_live_addr,
-        release_tag_download_url, release_tag_from_effective_url, release_version_from_tag,
-        render_status_clear, render_status_overlay, requested_env, resolved_startup_command,
-        retire_stream_state, retransmit_stream_opens, rewrite_forward_command,
+        parse_remote_forward, parse_ssh_config, parse_trace_options, parse_update_options,
+        post_submit_hold_duration, queue_pending_user_input, raw_contains_host_table,
+        recv_response_until, refresh_live_addr, release_tag_download_url,
+        release_tag_from_effective_url, release_version_from_tag, render_status_clear,
+        render_status_overlay, requested_env, resolved_startup_command, retire_stream_state,
+        retransmit_stream_opens, rewrite_forward_command, sanitize_trace_name,
         selected_predict_mode, selected_udp_host, server_version_mismatch,
         should_flush_terminal_input_after_contact, should_hold_during_startup_gate,
         should_hold_post_submit_input, should_repaint_idle_alternate_screen,
@@ -9554,6 +9776,56 @@ mod tests {
         assert!(parse_update_options(&["--client".to_string(), "--server".to_string()]).is_err());
     }
 
+    #[test]
+    fn trace_options_parse_host_command_and_defaults() {
+        let parsed = parse_trace_options(&["palav".to_string(), "tm".to_string()]).unwrap();
+
+        assert_eq!(parsed.host, "palav");
+        assert_eq!(parsed.command, vec!["tm"]);
+        assert!(parsed.bytes);
+        assert!(
+            parsed
+                .client_log
+                .to_string_lossy()
+                .contains("client-palav-")
+        );
+    }
+
+    #[test]
+    fn trace_options_accept_client_log_and_no_bytes() {
+        let parsed = parse_trace_options(&[
+            "--no-bytes".to_string(),
+            "--client-log".to_string(),
+            "/tmp/dosh-client.log".to_string(),
+            "palav".to_string(),
+            "--".to_string(),
+            "echo".to_string(),
+            "ok".to_string(),
+        ])
+        .unwrap();
+
+        assert_eq!(parsed.host, "palav");
+        assert_eq!(parsed.command, vec!["echo", "ok"]);
+        assert_eq!(
+            parsed.client_log,
+            std::path::PathBuf::from("/tmp/dosh-client.log")
+        );
+        assert!(!parsed.bytes);
+    }
+
+    #[test]
+    fn trace_options_reject_unknown_options_before_host() {
+        assert!(parse_trace_options(&["--wat".to_string(), "palav".to_string()]).is_err());
+        assert!(parse_trace_options(&[]).is_err());
+    }
+
+    #[test]
+    fn trace_log_name_is_shell_and_path_safe() {
+        assert_eq!(sanitize_trace_name("palav"), "palav");
+        assert_eq!(sanitize_trace_name("user@host:50000"), "user_host_50000");
+        assert_eq!(sanitize_trace_name(""), "host");
+    }
+
     #[test]
     fn update_installer_uses_platform_native_script() {
         assert_eq!(