Add Unix daemon mode with PID file and privilege dropping

Implement core daemon infrastructure for running telemt as a background
  service on Unix platforms (Linux, FreeBSD, etc.):

  - Add src/daemon module with classic double-fork daemonization
  - Implement flock-based PID file management to prevent duplicate instances
  - Add privilege dropping (setuid/setgid) after socket binding
  - New CLI flags: --daemon, --foreground, --pid-file, --run-as-user,
    --run-as-group, --working-dir

  Daemonization occurs before tokio runtime starts to ensure clean fork.
  PID file uses exclusive locking to detect already-running instances.
  Privilege dropping happens after bind_listeners() to allow binding
  to privileged ports (< 1024) before switching to unprivileged user.

Signed-off-by: Vladimir Krivopalov <argenet@yandex.ru>
This commit is contained in:
Vladimir Krivopalov
2026-03-20 20:31:47 +02:00
committed by Vladimir Krivopalov
parent 2d3c2807ab
commit 2ea7813ed4
6 changed files with 789 additions and 34 deletions

View File

@@ -25,7 +25,15 @@ pub(crate) fn resolve_runtime_config_path(
absolute.canonicalize().unwrap_or(absolute)
}
pub(crate) fn parse_cli() -> (String, Option<PathBuf>, bool, Option<String>) {
/// Parsed CLI arguments.
pub(crate) struct CliArgs {
pub config_path: String,
pub data_path: Option<PathBuf>,
pub silent: bool,
pub log_level: Option<String>,
}
pub(crate) fn parse_cli() -> CliArgs {
let mut config_path = "config.toml".to_string();
let mut data_path: Option<PathBuf> = None;
let mut silent = false;
@@ -72,36 +80,35 @@ pub(crate) fn parse_cli() -> (String, Option<PathBuf>, bool, Option<String>) {
log_level = Some(s.trim_start_matches("--log-level=").to_string());
}
"--help" | "-h" => {
eprintln!("Usage: telemt [config.toml] [OPTIONS]");
eprintln!();
eprintln!("Options:");
eprintln!(
" --data-path <DIR> Set data directory (absolute path; overrides config value)"
);
eprintln!(" --silent, -s Suppress info logs");
eprintln!(" --log-level <LEVEL> debug|verbose|normal|silent");
eprintln!(" --help, -h Show this help");
eprintln!();
eprintln!("Setup (fire-and-forget):");
eprintln!(
" --init Generate config, install systemd service, start"
);
eprintln!(" --port <PORT> Listen port (default: 443)");
eprintln!(
" --domain <DOMAIN> TLS domain for masking (default: www.google.com)"
);
eprintln!(
" --secret <HEX> 32-char hex secret (auto-generated if omitted)"
);
eprintln!(" --user <NAME> Username (default: user)");
eprintln!(" --config-dir <DIR> Config directory (default: /etc/telemt)");
eprintln!(" --no-start Don't start the service after install");
print_help();
std::process::exit(0);
}
"--version" | "-V" => {
println!("telemt {}", env!("CARGO_PKG_VERSION"));
std::process::exit(0);
}
// Skip daemon-related flags (already parsed)
"--daemon" | "-d" | "--foreground" | "-f" => {}
s if s.starts_with("--pid-file") => {
if !s.contains('=') {
i += 1; // skip value
}
}
s if s.starts_with("--run-as-user") => {
if !s.contains('=') {
i += 1;
}
}
s if s.starts_with("--run-as-group") => {
if !s.contains('=') {
i += 1;
}
}
s if s.starts_with("--working-dir") => {
if !s.contains('=') {
i += 1;
}
}
s if !s.starts_with('-') => {
config_path = s.to_string();
}
@@ -112,7 +119,49 @@ pub(crate) fn parse_cli() -> (String, Option<PathBuf>, bool, Option<String>) {
i += 1;
}
(config_path, data_path, silent, log_level)
CliArgs {
config_path,
data_path,
silent,
log_level,
}
}
fn print_help() {
eprintln!("Usage: telemt [config.toml] [OPTIONS]");
eprintln!();
eprintln!("Options:");
eprintln!(" --data-path <DIR> Set data directory (absolute path; overrides config value)");
eprintln!(" --silent, -s Suppress info logs");
eprintln!(" --log-level <LEVEL> debug|verbose|normal|silent");
eprintln!(" --help, -h Show this help");
eprintln!(" --version, -V Show version");
eprintln!();
#[cfg(unix)]
{
eprintln!("Daemon options (Unix only):");
eprintln!(" --daemon, -d Fork to background (daemonize)");
eprintln!(" --foreground, -f Explicit foreground mode (for systemd)");
eprintln!(" --pid-file <PATH> PID file path (default: /var/run/telemt.pid)");
eprintln!(" --run-as-user <USER> Drop privileges to this user after binding");
eprintln!(" --run-as-group <GROUP> Drop privileges to this group after binding");
eprintln!(" --working-dir <DIR> Working directory for daemon mode");
eprintln!();
}
eprintln!("Setup (fire-and-forget):");
eprintln!(
" --init Generate config, install systemd service, start"
);
eprintln!(" --port <PORT> Listen port (default: 443)");
eprintln!(
" --domain <DOMAIN> TLS domain for masking (default: www.google.com)"
);
eprintln!(
" --secret <HEX> 32-char hex secret (auto-generated if omitted)"
);
eprintln!(" --user <NAME> Username (default: user)");
eprintln!(" --config-dir <DIR> Config directory (default: /etc/telemt)");
eprintln!(" --no-start Don't start the service after install");
}
#[cfg(test)]

View File

@@ -47,8 +47,56 @@ use crate::transport::UpstreamManager;
use crate::transport::middle_proxy::MePool;
use helpers::{parse_cli, resolve_runtime_config_path};
#[cfg(unix)]
use crate::daemon::{DaemonOptions, PidFile, drop_privileges};
/// Runs the full telemt runtime startup pipeline and blocks until shutdown.
///
/// On Unix, daemon options should be handled before calling this function
/// (daemonization must happen before tokio runtime starts).
#[cfg(unix)]
pub async fn run_with_daemon(
daemon_opts: DaemonOptions,
) -> std::result::Result<(), Box<dyn std::error::Error>> {
run_inner(daemon_opts).await
}
/// Runs the full telemt runtime startup pipeline and blocks until shutdown.
///
/// This is the main entry point for non-daemon mode or when called as a library.
#[allow(dead_code)]
pub async fn run() -> std::result::Result<(), Box<dyn std::error::Error>> {
#[cfg(unix)]
{
// Parse CLI to get daemon options even in simple run() path
let args: Vec<String> = std::env::args().skip(1).collect();
let daemon_opts = crate::cli::parse_daemon_args(&args);
run_inner(daemon_opts).await
}
#[cfg(not(unix))]
{
run_inner().await
}
}
#[cfg(unix)]
async fn run_inner(
daemon_opts: DaemonOptions,
) -> std::result::Result<(), Box<dyn std::error::Error>> {
// Acquire PID file if daemonizing or if explicitly requested
// Keep it alive until shutdown (underscore prefix = intentionally kept for RAII cleanup)
let _pid_file = if daemon_opts.daemonize || daemon_opts.pid_file.is_some() {
let mut pf = PidFile::new(daemon_opts.pid_file_path());
if let Err(e) = pf.acquire() {
eprintln!("[telemt] {}", e);
std::process::exit(1);
}
Some(pf)
} else {
None
};
let process_started_at = Instant::now();
let process_started_at_epoch_secs = SystemTime::now()
.duration_since(UNIX_EPOCH)
@@ -61,7 +109,11 @@ pub async fn run() -> std::result::Result<(), Box<dyn std::error::Error>> {
Some("load and validate config".to_string()),
)
.await;
let (config_path_cli, data_path, cli_silent, cli_log_level) = parse_cli();
let cli_args = parse_cli();
let config_path_cli = cli_args.config_path;
let data_path = cli_args.data_path;
let cli_silent = cli_args.silent;
let cli_log_level = cli_args.log_level;
let startup_cwd = match std::env::current_dir() {
Ok(cwd) => cwd,
Err(e) => {
@@ -585,6 +637,17 @@ pub async fn run() -> std::result::Result<(), Box<dyn std::error::Error>> {
std::process::exit(1);
}
// Drop privileges after binding sockets (which may require root for port < 1024)
if daemon_opts.user.is_some() || daemon_opts.group.is_some() {
if let Err(e) = drop_privileges(
daemon_opts.user.as_deref(),
daemon_opts.group.as_deref(),
) {
error!(error = %e, "Failed to drop privileges");
std::process::exit(1);
}
}
runtime_tasks::apply_runtime_log_filter(
has_rust_log,
&effective_log_level,