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// Copyright Materialize, Inc. and contributors. All rights reserved.
//
// Use of this software is governed by the Business Source License
// included in the LICENSE file.
//
// As of the Change Date specified in that file, in accordance with
// the Business Source License, use of this software will be governed
// by the Apache License, Version 2.0.
//! Methods common to servers listening for TCP connections.
use std::future::Future;
use std::io;
use std::net::SocketAddr;
use std::path::PathBuf;
use std::pin::Pin;
use std::sync::{Arc, RwLock, RwLockReadGuard};
use std::time::Duration;
use anyhow::bail;
use futures::stream::{BoxStream, Stream, StreamExt};
use mz_ore::error::ErrorExt;
use mz_ore::task::JoinSetExt;
use openssl::ssl::{SslAcceptor, SslContext, SslFiletype, SslMethod};
use socket2::{SockRef, TcpKeepalive};
use tokio::net::{TcpListener, TcpStream};
use tokio::sync::oneshot;
use tokio::task::JoinSet;
use tokio_stream::wrappers::{IntervalStream, TcpListenerStream};
use tracing::{debug, error, warn};
/// TCP keepalive settings. The idle time and interval match CockroachDB [0].
/// The number of retries matches the Linux default.
///
/// [0]: https://github.com/cockroachdb/cockroach/pull/14063
const KEEPALIVE: TcpKeepalive = TcpKeepalive::new()
.with_time(Duration::from_secs(60))
.with_interval(Duration::from_secs(60))
.with_retries(9);
/// A future that handles a connection.
pub type ConnectionHandler = Pin<Box<dyn Future<Output = Result<(), anyhow::Error>> + Send>>;
/// A server handles incoming network connections.
pub trait Server {
/// Returns the name of the connection handler for use in e.g. log messages.
const NAME: &'static str;
/// Handles a single connection.
fn handle_connection(&self, conn: TcpStream) -> ConnectionHandler;
}
/// A stream of incoming connections.
pub trait ConnectionStream: Stream<Item = io::Result<TcpStream>> + Unpin + Send {}
impl<T> ConnectionStream for T where T: Stream<Item = io::Result<TcpStream>> + Unpin + Send {}
/// A handle to a listener created by [`listen`].
#[derive(Debug)]
pub struct ListenerHandle {
local_addr: SocketAddr,
_trigger: oneshot::Sender<()>,
}
impl ListenerHandle {
/// Returns the local address to which the listener is bound.
pub fn local_addr(&self) -> SocketAddr {
self.local_addr
}
}
/// Listens for incoming TCP connections on the specified address.
///
/// Returns a handle to the listener and the stream of incoming connections
/// produced by the listener. When the handle is dropped, the listener is
/// closed, and the stream of incoming connections terminates.
pub async fn listen(
addr: &SocketAddr,
) -> Result<(ListenerHandle, Pin<Box<dyn ConnectionStream>>), io::Error> {
let listener = TcpListener::bind(addr).await?;
let local_addr = listener.local_addr()?;
let (trigger, tripwire) = oneshot::channel();
let handle = ListenerHandle {
local_addr,
_trigger: trigger,
};
// TODO(benesch): replace `TCPListenerStream`s with `listener.incoming()` if
// that is restored when the `Stream` trait stabilizes.
let stream = TcpListenerStream::new(listener).take_until(tripwire);
Ok((handle, Box::pin(stream)))
}
/// Serves incoming TCP connections from `conns` using `server`. `wait_timeout` is the time to wait
/// after `conns` terminates for outstanding connections to complete. Returns handles to the
/// outstanding connections after `wait_timeout` has expired or all connections have completed.
pub async fn serve<C, S>(mut conns: C, server: S, wait_timeout: Option<Duration>) -> JoinSet<()>
where
C: ConnectionStream,
S: Server,
{
let task_name = format!("handle_{}_connection", S::NAME);
let mut set = JoinSet::new();
loop {
tokio::select! {
// next() is cancel safe.
conn = conns.next() => {
let conn = match conn {
None => break,
Some(Ok(conn)) => conn,
Some(Err(err)) => {
error!("error accepting connection: {}", err);
continue;
}
};
// Set TCP_NODELAY to disable tinygram prevention (Nagle's
// algorithm), which forces a 40ms delay between each query
// on linux. According to John Nagle [0], the true problem
// is delayed acks, but disabling those is a receive-side
// operation (TCP_QUICKACK), and we can't always control the
// client. PostgreSQL sets TCP_NODELAY on both sides of its
// sockets, so it seems sane to just do the same.
//
// If set_nodelay fails, it's a programming error, so panic.
//
// [0]: https://news.ycombinator.com/item?id=10608356
conn.set_nodelay(true).expect("set_nodelay failed");
// Enable TCP keepalives to avoid any idle connection timeouts that may
// be enforced by networking devices between us and the client. Idle SQL
// connections are expected--e.g., a `SUBSCRIBE` to a view containing
// critical alerts will ideally be producing no data most of the time.
if let Err(e) = SockRef::from(&conn).set_tcp_keepalive(&KEEPALIVE) {
error!("failed enabling keepalive: {e}");
continue;
}
let fut = server.handle_connection(conn);
set.spawn_named(|| &task_name, async {
if let Err(e) = fut.await {
debug!(
"error handling connection in {}: {}",
S::NAME,
e.display_with_causes()
);
}
});
}
// Actively cull completed tasks from the JoinSet so it does not grow unbounded. This
// method is cancel safe.
res = set.join_next(), if set.len() > 0 => {
if let Some(Err(e)) = res {
debug!(
"error joining connection in {}: {}",
S::NAME,
e.display_with_causes()
);
}
}
}
}
if let Some(wait) = wait_timeout {
if set.len() > 0 {
warn!(
"{} exiting, {} outstanding connections, waiting for {:?}",
S::NAME,
set.len(),
wait
);
}
let timedout = tokio::time::timeout(wait, async {
while let Some(res) = set.join_next().await {
if let Err(e) = res {
debug!(
"error joining connection in {}: {}",
S::NAME,
e.display_with_causes()
);
}
}
})
.await;
if timedout.is_err() {
warn!(
"{}: wait timeout of {:?} exceeded, {} outstanding connections",
S::NAME,
wait,
set.len()
);
}
}
set
}
/// Configures a server's TLS encryption and authentication.
#[derive(Clone, Debug)]
pub struct TlsConfig {
/// The SSL context used to manage incoming TLS negotiations.
pub context: SslContext,
/// The TLS mode.
pub mode: TlsMode,
}
/// Specifies how strictly to enforce TLS encryption.
#[derive(Debug, Clone, Copy)]
pub enum TlsMode {
/// Allow TLS encryption.
Allow,
/// Require that clients negotiate TLS encryption.
Require,
}
/// Configures TLS encryption for connections.
#[derive(Debug, Clone)]
pub struct TlsCertConfig {
/// The path to the TLS certificate.
pub cert: PathBuf,
/// The path to the TLS key.
pub key: PathBuf,
}
impl TlsCertConfig {
/// Returns the SSL context to use in TlsConfigs.
pub fn load_context(&self) -> Result<SslContext, anyhow::Error> {
// Mozilla publishes three presets: old, intermediate, and modern. They
// recommend the intermediate preset for general purpose servers, which
// is what we use, as it is compatible with nearly every client released
// in the last five years but does not include any known-problematic
// ciphers. We once tried to use the modern preset, but it was
// incompatible with Fivetran, and presumably other JDBC-based tools.
let mut builder = SslAcceptor::mozilla_intermediate_v5(SslMethod::tls())?;
builder.set_certificate_chain_file(&self.cert)?;
builder.set_private_key_file(&self.key, SslFiletype::PEM)?;
Ok(builder.build().into_context())
}
/// Like [Self::load_context] but attempts to reload the files each time `ticker` yields an item.
/// Returns an error based on the files currently on disk. When `ticker` receives, the
/// certificates are reloaded from the context. The result of the reloading is returned on the
/// oneshot if present, and an Ok result means new connections will use the new certificates. An
/// Err result will not change the current certificates.
pub fn reloading_context(
&self,
mut ticker: ReloadTrigger,
) -> Result<ReloadingSslContext, anyhow::Error> {
let context = Arc::new(RwLock::new(self.load_context()?));
let updater_context = Arc::clone(&context);
let config = self.clone();
mz_ore::task::spawn(|| "TlsCertConfig reloading_context", async move {
while let Some(chan) = ticker.next().await {
let result = match config.load_context() {
Ok(ctx) => {
*updater_context.write().expect("poisoned") = ctx;
Ok(())
}
Err(err) => {
tracing::error!("failed to reload SSL certificate: {err}");
Err(err)
}
};
if let Some(chan) = chan {
let _ = chan.send(result);
}
}
tracing::warn!("TlsCertConfig reloading_context updater closed");
});
Ok(ReloadingSslContext { context })
}
}
/// An SslContext whose inner value can be updated.
#[derive(Clone, Debug)]
pub struct ReloadingSslContext {
/// The current SSL context.
context: Arc<RwLock<SslContext>>,
}
impl ReloadingSslContext {
pub fn get(&self) -> RwLockReadGuard<SslContext> {
self.context.read().expect("poisoned")
}
}
/// Configures a server's TLS encryption and authentication with reloading.
#[derive(Clone, Debug)]
pub struct ReloadingTlsConfig {
/// The SSL context used to manage incoming TLS negotiations.
pub context: ReloadingSslContext,
/// The TLS mode.
pub mode: TlsMode,
}
pub type ReloadTrigger = BoxStream<'static, Option<oneshot::Sender<Result<(), anyhow::Error>>>>;
/// Returns a ReloadTrigger that triggers once per hour.
pub fn default_cert_reload_ticker() -> ReloadTrigger {
let ticker = IntervalStream::new(tokio::time::interval(Duration::from_secs(60 * 60)));
let ticker = ticker.map(|_| None);
let ticker = Box::pin(ticker);
ticker
}
/// Returns a ReloadTrigger that never triggers.
pub fn cert_reload_never_reload() -> ReloadTrigger {
let ticker = futures::stream::empty();
let ticker = Box::pin(ticker);
ticker
}
/// Command line arguments for TLS.
#[derive(Debug, Clone, clap::Parser)]
pub struct TlsCliArgs {
/// How stringently to demand TLS authentication and encryption.
///
/// If set to "disable", then environmentd rejects HTTP and PostgreSQL
/// connections that negotiate TLS.
///
/// If set to "require", then environmentd requires that all HTTP and
/// PostgreSQL connections negotiate TLS. Unencrypted connections will be
/// rejected.
#[clap(
long, env = "TLS_MODE",
possible_values = &["disable", "require"],
default_value = "disable",
default_value_ifs = &[
("frontegg-tenant", None, Some("require")),
("frontegg-resolver-template", None, Some("require")),
],
value_name = "MODE",
)]
tls_mode: String,
/// Certificate file for TLS connections.
#[clap(
long,
env = "TLS_CERT",
requires = "tls-key",
required_if_eq_any(&[("tls-mode", "require")]),
value_name = "PATH"
)]
tls_cert: Option<PathBuf>,
/// Private key file for TLS connections.
#[clap(
long,
env = "TLS_KEY",
requires = "tls-cert",
required_if_eq_any(&[("tls-mode", "require")]),
value_name = "PATH"
)]
tls_key: Option<PathBuf>,
}
impl TlsCliArgs {
/// Convert args into configuration.
pub fn into_config(self) -> Result<Option<TlsCertConfig>, anyhow::Error> {
if self.tls_mode == "disable" {
if self.tls_cert.is_some() {
bail!("cannot specify --tls-mode=disable and --tls-cert simultaneously");
}
if self.tls_key.is_some() {
bail!("cannot specify --tls-mode=disable and --tls-key simultaneously");
}
Ok(None)
} else {
let cert = self.tls_cert.unwrap();
let key = self.tls_key.unwrap();
Ok(Some(TlsCertConfig { cert, key }))
}
}
}