faucet_server/server/router/

mod.rs

use std::{
    collections::HashSet, ffi::OsStr, net::SocketAddr, num::NonZeroUsize, path::PathBuf, pin::pin,
    sync::Arc,
};

use hyper::{body::Incoming, server::conn::http1, service::service_fn, Request, Uri};
use hyper_util::rt::TokioIo;
use tokio::net::TcpListener;
use tokio_tungstenite::tungstenite::{http::uri::PathAndQuery, protocol::WebSocketConfig};

use super::{onion::Service, FaucetServerBuilder, FaucetServerService};
use crate::{
    client::{
        load_balancing::{IpExtractor, Strategy},
        worker::{WorkerConfigs, WorkerType},
        ExclusiveBody,
    },
    error::{FaucetError, FaucetResult},
    shutdown::ShutdownSignal,
};

fn default_workdir() -> PathBuf {
    PathBuf::from(".")
}

#[derive(serde::Deserialize)]
struct ReducedServerConfig {
    pub strategy: Option<Strategy>,
    #[serde(default = "default_workdir")]
    pub workdir: PathBuf,
    pub app_dir: Option<String>,
    pub workers: NonZeroUsize,
    pub server_type: WorkerType,
    pub qmd: Option<PathBuf>,
    pub max_rps: Option<f64>,
}

#[derive(serde::Deserialize)]
struct RouteConfig {
    route: String,
    #[serde(flatten)]
    config: ReducedServerConfig,
}

#[derive(serde::Deserialize)]
pub struct RouterConfig {
    route: Vec<RouteConfig>,
}

#[derive(Clone)]
struct RouterService {
    routes: &'static [String],
    clients: Arc<[FaucetServerService]>,
}

fn strip_prefix_exact(path_and_query: &PathAndQuery, prefix: &str) -> Option<PathAndQuery> {
    if path_and_query.path() == prefix {
        return Some(match path_and_query.query() {
            Some(query) => format!("/?{query}").parse().unwrap(),
            None => "/".parse().unwrap(),
        });
    }
    None
}

fn strip_prefix_relative(path_and_query: &PathAndQuery, prefix: &str) -> Option<PathAndQuery> {
    // Try to strip the prefix. It is fails we short-circuit.
    let after_prefix = path_and_query.path().strip_prefix(prefix)?;

    let start_slash = after_prefix.starts_with('/');

    Some(match (start_slash, path_and_query.query()) {
        (true, None) => after_prefix.parse().unwrap(),
        (true, Some(query)) => format!("{after_prefix}?{query}").parse().unwrap(),
        (false, None) => format!("/{after_prefix}").parse().unwrap(),
        (false, Some(query)) => format!("/{after_prefix}?{query}").parse().unwrap(),
    })
}

fn strip_prefix(uri: &Uri, prefix: &str) -> Option<Uri> {
    let path_and_query = uri.path_and_query()?;

    let new_path_and_query = match prefix.ends_with('/') {
        true => strip_prefix_relative(path_and_query, prefix)?,
        false => strip_prefix_exact(path_and_query, prefix)?,
    };

    let mut parts = uri.clone().into_parts();
    parts.path_and_query = Some(new_path_and_query);

    Some(Uri::from_parts(parts).unwrap())
}

impl Service<hyper::Request<Incoming>> for RouterService {
    type Error = FaucetError;
    type Response = hyper::Response<ExclusiveBody>;
    async fn call(
        &self,
        mut req: hyper::Request<Incoming>,
        ip_addr: Option<std::net::IpAddr>,
    ) -> Result<Self::Response, Self::Error> {
        let mut client = None;
        for i in 0..self.routes.len() {
            let route = &self.routes[i];
            if let Some(new_uri) = strip_prefix(req.uri(), route) {
                client = Some(&self.clients[i]);
                *req.uri_mut() = new_uri;
                break;
            }
        }
        match client {
            None => Ok(hyper::Response::builder()
                .status(404)
                .body(ExclusiveBody::plain_text("404 not found"))
                .expect("Response should build")),
            Some(client) => client.call(req, ip_addr).await,
        }
    }
}

impl RouterConfig {
    async fn into_service(
        self,
        rscript: impl AsRef<OsStr>,
        quarto: impl AsRef<OsStr>,
        ip_from: IpExtractor,
        shutdown: &'static ShutdownSignal,
        websocket_config: &'static WebSocketConfig,
    ) -> FaucetResult<(RouterService, Vec<WorkerConfigs>)> {
        let mut all_workers = Vec::with_capacity(self.route.len());
        let mut routes = Vec::with_capacity(self.route.len());
        let mut clients = Vec::with_capacity(self.route.len());
        let mut routes_set = HashSet::with_capacity(self.route.len());
        for route_conf in self.route.into_iter() {
            let route = route_conf.route;
            if !routes_set.insert(route.clone()) {
                return Err(FaucetError::DuplicateRoute(route));
            }
            let (client, workers) = FaucetServerBuilder::new()
                .workdir(route_conf.config.workdir)
                .server_type(route_conf.config.server_type)
                .strategy(route_conf.config.strategy)
                .rscript(&rscript)
                .quarto(&quarto)
                .qmd(route_conf.config.qmd)
                .workers(route_conf.config.workers.get())
                .extractor(ip_from)
                .app_dir(route_conf.config.app_dir)
                .route(route.clone())
                .max_rps(route_conf.config.max_rps)
                .build()?
                .extract_service(shutdown, websocket_config)
                .await?;
            routes.push(route);
            all_workers.push(workers);
            clients.push(client);
        }
        let routes = routes.leak();
        let clients = clients.into();
        let service = RouterService { clients, routes };
        Ok((service, all_workers))
    }
}

impl RouterConfig {
    pub async fn run(
        self,
        rscript: impl AsRef<OsStr>,
        quarto: impl AsRef<OsStr>,
        ip_from: IpExtractor,
        addr: SocketAddr,
        shutdown: &'static ShutdownSignal,
        websocket_config: &'static WebSocketConfig,
    ) -> FaucetResult<()> {
        let (service, all_workers) = self
            .into_service(rscript, quarto, ip_from, shutdown, websocket_config)
            .await?;
        // Bind to the port and listen for incoming TCP connections
        let listener = TcpListener::bind(addr).await?;
        log::info!(target: "faucet", "Listening on http://{addr}");
        let main_loop = || async {
            loop {
                match listener.accept().await {
                    Err(e) => {
                        log::error!(target: "faucet", "Unable to accept TCP connection: {e}");
                        return;
                    }
                    Ok((tcp, client_addr)) => {
                        let tcp = TokioIo::new(tcp);
                        log::debug!(target: "faucet", "Accepted TCP connection from {client_addr}");

                        let service = service.clone();

                        tokio::task::spawn(async move {
                            let mut conn = http1::Builder::new()
                                .serve_connection(
                                    tcp,
                                    service_fn(|req: Request<Incoming>| {
                                        service.call(req, Some(client_addr.ip()))
                                    }),
                                )
                                .with_upgrades();

                            let conn = pin!(&mut conn);

                            tokio::select! {
                                result = conn => {
                                    if let Err(e) = result {
                                        log::error!(target: "faucet", "Connection error: {e:?}");
                                    }
                                }
                                _ = shutdown.wait() => ()
                            }
                        });
                    }
                }
            }
        };

        // Race the shutdown vs the main loop
        tokio::select! {
            _ = shutdown.wait() => (),
            _ = main_loop() => (),
        }

        // Kill child process
        for w in all_workers.iter().flat_map(|ws| &ws.workers) {
            w.wait_until_done().await;
        }

        FaucetResult::Ok(())
    }
}