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//! Optional TLS termination in the router itself.
//!
//! `gh` builds a custom host's REST base as `https://<host>/api/v3/` with no
//! plaintext option, so reaching the GitHub proxy required a separate TLS
//! terminator in front of the router. For a router deliberately *not* reachable
//! from outside — an internal-only sidecar on a private Docker network — that
//! meant standing up a reverse proxy and a private CA purely to satisfy a
//! client's HTTPS requirement, and the one surface most worth mediating (the
//! one that can delete repositories) was the one that could not be pointed at
//! the router (issue #263).
//!
//! Serving TLS here removes that step. `TLS_SELF_SIGNED=1` additionally
//! generates a certificate for the configured names, so a private-network
//! operator enables HTTPS without a CA at all; the certificate is written where
//! `router tls ca` can print it for clients to trust.
//!
//! Unset means unchanged: the router serves plain HTTP exactly as before.
use std::path::{Path, PathBuf};
/// Where the generated certificate and key live inside the data directory.
const GENERATED_DIRECTORY: &str = "tls";
const GENERATED_CERT: &str = "cert.pem";
const GENERATED_KEY: &str = "key.pem";
/// How the router should serve its main listener.
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum TlsSetup {
/// Serve plain HTTP, as the router always has.
Disabled,
/// Serve HTTPS from this certificate and key.
Enabled { cert: PathBuf, key: PathBuf },
}
impl TlsSetup {
/// Whether this setup serves HTTPS.
#[must_use]
pub const fn is_enabled(&self) -> bool {
matches!(self, Self::Enabled { .. })
}
}
/// Names a generated certificate is valid for.
///
/// A sidecar is reached by its network alias rather than a public hostname, so
/// the container name must be present or the certificate is useless for the
/// deployment it was generated for. Loopback names are included because an
/// operator debugging from inside the container reaches it that way.
#[must_use]
pub fn generated_subject_names(configured: &str) -> Vec<String> {
let mut names: Vec<String> = configured
.split(',')
.map(str::trim)
.filter(|name| !name.is_empty())
.map(str::to_string)
.collect();
for fallback in ["localhost", "127.0.0.1"] {
if !names.iter().any(|name| name == fallback) {
names.push(fallback.to_string());
}
}
names
}
/// Resolve the TLS setup from the environment.
///
/// An explicit certificate pair wins over generation, so an operator who has a
/// real certificate is never silently served a self-signed one.
///
/// # Errors
///
/// Returns a message when only one half of the pair is set — that is a
/// misconfiguration whose silent fallback to plaintext would be the opposite of
/// what was asked for — or when generation fails.
pub fn from_env(data_dir: &Path) -> Result<TlsSetup, String> {
let read = |name: &str| std::env::var(name).ok().filter(|value| !value.is_empty());
resolve(
data_dir,
read("TLS_CERT_FILE"),
read("TLS_KEY_FILE"),
read("TLS_SELF_SIGNED").as_deref() == Some("1"),
read("TLS_SELF_SIGNED_DNS"),
)
}
/// Decide the setup from already-read settings.
///
/// Split from [`from_env`] so every branch is reachable in a test: this crate
/// forbids `unsafe`, and mutating the process environment is the only other
/// way to drive them.
///
/// # Errors
///
/// Returns a message when only one half of the pair is given, or when
/// generation fails.
pub fn resolve(
data_dir: &Path,
cert: Option<String>,
key: Option<String>,
self_signed: bool,
self_signed_dns: Option<String>,
) -> Result<TlsSetup, String> {
match (cert, key) {
(Some(cert), Some(key)) => Ok(TlsSetup::Enabled {
cert: PathBuf::from(cert),
key: PathBuf::from(key),
}),
(Some(_), None) => Err("TLS_CERT_FILE is set without TLS_KEY_FILE".to_string()),
(None, Some(_)) => Err("TLS_KEY_FILE is set without TLS_CERT_FILE".to_string()),
(None, None) => {
if !self_signed {
return Ok(TlsSetup::Disabled);
}
let names = generated_subject_names(
&self_signed_dns.unwrap_or_else(|| "localhost".to_string()),
);
let (cert, key) = ensure_generated(data_dir, &names)?;
Ok(TlsSetup::Enabled { cert, key })
}
}
}
/// Paths of the generated certificate pair within `data_dir`.
#[must_use]
pub fn generated_paths(data_dir: &Path) -> (PathBuf, PathBuf) {
let directory = data_dir.join(GENERATED_DIRECTORY);
(
directory.join(GENERATED_CERT),
directory.join(GENERATED_KEY),
)
}
/// Generate a self-signed certificate for `names`, reusing an existing one.
///
/// Reused rather than regenerated on every start: clients are told to trust
/// this certificate, and rotating it on restart would break every one of them
/// without saying why.
///
/// # Errors
///
/// Returns a message when the certificate cannot be generated or written.
pub fn ensure_generated(data_dir: &Path, names: &[String]) -> Result<(PathBuf, PathBuf), String> {
let (cert_path, key_path) = generated_paths(data_dir);
if cert_path.is_file() && key_path.is_file() {
return Ok((cert_path, key_path));
}
let generated = rcgen::generate_simple_self_signed(names.to_vec())
.map_err(|error| format!("could not generate a self-signed certificate: {error}"))?;
let directory = cert_path
.parent()
.ok_or_else(|| "generated certificate has no directory".to_string())?;
std::fs::create_dir_all(directory)
.map_err(|error| format!("could not create {}: {error}", directory.display()))?;
crate::durable_file::atomic_write_owner_only(&cert_path, generated.cert.pem().as_bytes())
.map_err(|error| crate::durable_file::describe_write_failure(&cert_path, &error))?;
// The private key is written owner-only, like every other secret this
// crate persists.
crate::durable_file::atomic_write_owner_only(
&key_path,
generated.signing_key.serialize_pem().as_bytes(),
)
.map_err(|error| crate::durable_file::describe_write_failure(&key_path, &error))?;
Ok((cert_path, key_path))
}
/// The generated certificate in PEM form, for a client to trust.
///
/// # Errors
///
/// Returns a message when no certificate has been generated yet.
pub fn read_generated_certificate(data_dir: &Path) -> Result<String, String> {
let (cert_path, _) = generated_paths(data_dir);
std::fs::read_to_string(&cert_path).map_err(|error| {
format!(
"no generated certificate at {}: {error}; start the router with TLS_SELF_SIGNED=1 first",
cert_path.display()
)
})
}
/// Serve the application over HTTPS from a certificate pair.
///
/// Lives in the library so the large `axum_server` serve future is never part
/// of the binary's `main` state machine: on Windows that overflowed the 1 MB
/// main-thread stack for subcommands that never serve at all.
///
/// # Errors
///
/// Returns a message when the certificate cannot be loaded or the listener
/// cannot be bound.
pub async fn serve_https(
address: std::net::SocketAddr,
app: axum::Router,
cert: std::path::PathBuf,
key: std::path::PathBuf,
) -> Result<(), Box<dyn std::error::Error + Send + Sync>> {
tracing::info!("Serving HTTPS with certificate {}", cert.display());
let tls = axum_server::tls_rustls::RustlsConfig::from_pem_file(&cert, &key)
.await
.map_err(|error| {
format!(
"could not load the TLS certificate {}: {error}",
cert.display()
)
})?;
axum_server::bind_rustls(address, tls)
.serve(app.into_make_service())
.await?;
Ok(())
}
#[cfg(test)]
#[path = "tls_tests.rs"]
mod tests;