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use std::io::{self, Write};
use std::path::{Path, PathBuf};
use std::sync::atomic::{AtomicBool, Ordering};
use std::sync::Arc;
use std::time::{Duration, Instant};
use crate::api::client::{parse_response_value, ApiClientError};
use crate::api::schema::{Method, Request, ResponseResult, ServerSshAgentRegisterParams};
use crate::ipc::{LocalStream, LocalStreamRead, LocalStreamReadCount};
pub(super) struct Registration {
stop: Arc<AtomicBool>,
thread: Option<std::thread::JoinHandle<()>>,
}
impl Registration {
pub(super) fn start() -> Option<Self> {
let path = std::env::var("SSH_AUTH_SOCK")
.ok()
.filter(|path| !path.is_empty())?;
Self::start_at(path, crate::api::socket_path())
}
fn start_at(path: String, socket_path: PathBuf) -> Option<Self> {
let mut stream = match connect(&path, &socket_path) {
Ok(None) => return None,
Ok(stream) => stream,
Err(error) => {
tracing::debug!(%error, "SSH agent refresh unavailable; retrying while attached");
None
}
};
let stop = Arc::new(AtomicBool::new(false));
let worker_stop = stop.clone();
let thread = std::thread::spawn(move || {
let mut byte = [0];
while !worker_stop.load(Ordering::Relaxed) {
if let Some(connection) = stream.as_mut() {
if !matches!(
crate::ipc::poll_local_stream_read(connection, &mut byte),
Ok(LocalStreamRead::Pending)
) {
stream = None;
}
} else {
// Retry both initial API readiness and connections lost during handoff.
match connect(&path, &socket_path) {
Ok(None) => break,
result => stream = result.ok().flatten(),
}
}
std::thread::sleep(Duration::from_millis(100));
}
});
Some(Self {
stop,
thread: Some(thread),
})
}
}
impl Drop for Registration {
fn drop(&mut self) {
self.stop.store(true, Ordering::Relaxed);
if let Some(thread) = self.thread.take() {
let _ = thread.join();
}
}
}
fn connect(path: &str, socket_path: &Path) -> io::Result<Option<LocalStream>> {
let timeout = Duration::from_millis(500);
let status = crate::api::read_runtime_status_at(socket_path, timeout)?.ok_or_else(|| {
io::Error::new(
io::ErrorKind::NotConnected,
"SSH agent status API is not ready",
)
})?;
if !status
.capabilities
.is_some_and(|capabilities| capabilities.ssh_agent_registration)
{
return Ok(None);
}
let mut stream = crate::ipc::connect_local_stream(socket_path)?;
let request = Request {
id: "remote:ssh-agent".into(),
method: Method::ServerSshAgentRegister(ServerSshAgentRegisterParams {
socket_path: path.into(),
}),
};
serde_json::to_writer(&mut stream, &request)?;
stream.write_all(b"\n")?;
crate::ipc::set_local_stream_polling(&mut stream, true)?;
let deadline = Instant::now() + timeout;
let mut response = Vec::new();
let mut byte = [0];
while Instant::now() < deadline && response.len() < 4096 {
match crate::ipc::poll_local_stream_read_count(&mut stream, &mut byte)? {
LocalStreamReadCount::Data(_) if byte[0] == b'\n' => {
let response = match parse_response_value(serde_json::from_slice(&response)?) {
Ok(response) => response,
Err(ApiClientError::ErrorResponse(response))
if response.error.code == "invalid_ssh_agent" =>
{
tracing::debug!(error = %response.error.message, "SSH agent registration rejected");
return Ok(None);
}
Err(error) => return Err(io::Error::other(error)),
};
return match response.result {
ResponseResult::Ok {} => Ok(Some(stream)),
_ => Err(io::Error::other(
"unexpected SSH agent registration response",
)),
};
}
LocalStreamReadCount::Data(_) => response.push(byte[0]),
LocalStreamReadCount::Closed => {
return Err(io::Error::other("SSH agent registration closed"))
}
LocalStreamReadCount::Pending => std::thread::sleep(Duration::from_millis(10)),
}
}
Err(io::Error::new(
io::ErrorKind::TimedOut,
"SSH agent registration did not complete",
))
}
#[cfg(test)]
mod tests {
use super::*;
use std::io::{BufRead, BufReader, Read};
use std::os::unix::net::UnixListener;
#[test]
fn registration_stops_when_the_server_rejects_the_agent() {
let socket_path =
std::env::temp_dir().join(format!("herdr-agent-rejected-{}.sock", std::process::id()));
let listener = UnixListener::bind(&socket_path).unwrap();
let server = std::thread::spawn(move || {
for expected in ["ping", "server.ssh_agent.register"] {
let (mut stream, _) = listener.accept().unwrap();
stream
.set_read_timeout(Some(Duration::from_secs(5)))
.unwrap();
let mut line = String::new();
BufReader::new(&mut stream).read_line(&mut line).unwrap();
let request: serde_json::Value = serde_json::from_str(&line).unwrap();
assert_eq!(request["method"], expected);
let response = if expected == "ping" {
serde_json::json!({"id": request["id"], "result": {
"type": "pong", "version": "test", "protocol": crate::protocol::PROTOCOL_VERSION,
"capabilities": {"live_handoff": false, "ssh_agent_registration": true}
}})
} else {
serde_json::json!({"id": request["id"], "error": {
"code": "invalid_ssh_agent", "message": "invalid agent path"
}})
};
writeln!(stream, "{response}").unwrap();
}
});
let registration =
Registration::start_at("relative-agent.sock".into(), socket_path.clone());
server.join().unwrap();
std::fs::remove_file(socket_path).unwrap();
assert!(
registration.is_none(),
"a rejected agent must not start a retry worker"
);
}
#[test]
fn registration_retries_when_the_api_is_initially_missing() {
let socket_path =
std::env::temp_dir().join(format!("herdr-agent-retry-{}.sock", std::process::id()));
let registration = Registration::start_at("/test/agent.sock".into(), socket_path.clone())
.expect("missing API must not permanently disable registration");
let listener = UnixListener::bind(&socket_path).unwrap();
listener.set_nonblocking(true).unwrap();
for (attempt, expected) in [
"ping",
"server.ssh_agent.register",
"ping",
"server.ssh_agent.register",
]
.into_iter()
.enumerate()
{
let deadline = Instant::now() + Duration::from_secs(5);
let mut stream = loop {
match listener.accept() {
Ok((stream, _)) => {
stream.set_nonblocking(false).unwrap();
break stream;
}
Err(error) if error.kind() == io::ErrorKind::WouldBlock => {
assert!(Instant::now() < deadline, "registration did not retry");
std::thread::sleep(Duration::from_millis(10));
}
Err(error) => panic!("{error}"),
}
};
stream
.set_read_timeout(Some(Duration::from_secs(5)))
.unwrap();
let mut line = String::new();
BufReader::new(&mut stream).read_line(&mut line).unwrap();
let request: serde_json::Value = serde_json::from_str(&line).unwrap();
assert_eq!(request["method"], expected);
if attempt == 1 {
writeln!(stream, "{}", serde_json::json!({"id": request["id"], "error": {
"code": "ssh_agent_unavailable", "message": "replacement server owns the address"
}})).unwrap();
continue;
}
let result = if expected == "ping" {
serde_json::json!({"type": "pong", "version": "test", "protocol": crate::protocol::PROTOCOL_VERSION,
"capabilities": {"live_handoff": false, "ssh_agent_registration": true}})
} else {
serde_json::json!({"type": "ok"})
};
writeln!(
stream,
"{}",
serde_json::json!({"id": request["id"], "result": result})
)
.unwrap();
if expected == "server.ssh_agent.register" {
drop(registration);
assert_eq!(stream.read(&mut [0]).unwrap(), 0);
break;
}
}
std::fs::remove_file(socket_path).unwrap();
}
}
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