rust_web_server/app/

mod.rs

#[cfg(test)]
mod tests;

pub mod controller;

use std::sync::Arc;

use crate::app::controller::directory_listing::DirectoryListingAssetsController;
use crate::app::controller::favicon::FaviconController;
use crate::app::controller::health::HealthController;
use crate::app::controller::ready::ReadyController;
use crate::app::controller::metrics::MetricsController;
use crate::app::controller::file::initiate::FileUploadInitiateController;
use crate::app::controller::form::get_method::FormGetMethodController;
use crate::app::controller::form::multipart_enctype_post_method::FormMultipartEnctypePostMethodController;
use crate::app::controller::form::url_encoded_enctype_post_method::FormUrlEncodedEnctypePostMethodController;
use crate::app::controller::index::IndexController;
use crate::app::controller::not_found::NotFoundController;
use crate::app::controller::script::ScriptController;
use crate::app::controller::static_resource::StaticResourceController;
use crate::app::controller::style::StyleController;
use crate::application::Application;
use crate::controller::Controller;
use crate::core::New;
use crate::header::Header;
use crate::mcp::McpServer;
use crate::middleware::{Middleware, WithMiddleware};
use crate::request::Request;
use crate::response::{Response, STATUS_CODE_REASON_PHRASE};
use crate::server::ConnectionInfo;
use crate::server_config::ServerConfig;
use crate::state::AppWithState;

/// A pair of function pointers representing one entry in the controller chain.
struct ControllerEntry {
    is_matching: fn(&Request, &ConnectionInfo) -> bool,
    process: fn(&Request, Response, &ConnectionInfo) -> Response,
}

/// Build a [`ControllerEntry`] from any type that implements [`Controller`].
fn entry<C: Controller>() -> ControllerEntry {
    ControllerEntry {
        is_matching: C::is_matching,
        process: C::process,
    }
}

/// The built-in HTTP application. Serves static files, favicons, forms,
/// file uploads, health probes, metrics, and a 404 fallback.
///
/// Use as-is or compose with the framework's building blocks:
///
/// ```rust,no_run
/// use rust_web_server::app::App;
/// use rust_web_server::middleware::{WithMiddleware, RateLimitLayer};
/// use rust_web_server::core::New;
///
/// // Middleware stack around the built-in app
/// let app = App::new().wrap(RateLimitLayer);
/// ```
///
/// For user-defined routes with shared state, call [`App::with_state`]:
///
/// ```rust,no_run
/// use rust_web_server::app::App;
/// use rust_web_server::response::{Response, STATUS_CODE_REASON_PHRASE};
/// use rust_web_server::core::New;
///
/// struct State { version: &'static str }
///
/// let app = App::with_state(State { version: "1.0" })
///     .get("/version", |_req, _params, _conn, state| {
///         let mut r = Response::new();
///         r.status_code = *STATUS_CODE_REASON_PHRASE.n200_ok.status_code;
///         r.reason_phrase = STATUS_CODE_REASON_PHRASE.n200_ok.reason_phrase.to_string();
///         r
///     });
/// ```
///
/// # Per-instance configuration
///
/// By default `App::new()` reads CORS, CSP, and other settings from
/// environment variables on each request (matching the current process state,
/// including hot-reloaded values). Call [`App::with_config`] to pin the
/// configuration to a specific [`ServerConfig`] — this is the recommended
/// pattern for parallel integration tests, which should not touch environment
/// variables at all.
///
/// ```rust,ignore
/// use rust_web_server::app::App;
/// use rust_web_server::server_config::ServerConfig;
/// use rust_web_server::test_client::TestClient;
///
/// // No env writes, no lock needed — safe to run in parallel.
/// let app = App::with_config(ServerConfig {
///     cors_allow_all: false,
///     cors_allow_origins: "https://trusted.example.com".to_string(),
///     ..ServerConfig::default()
/// });
/// let client = TestClient::new(app);
/// ```
#[derive(Clone)]
pub struct App {
    /// When `Some`, every request is served using this fixed config.
    /// When `None`, config is read from environment variables on each request
    /// (supports hot-reload via SIGHUP / `POST /admin/config/reload`).
    config: Option<Arc<ServerConfig>>,
}

impl New for App {
    fn new() -> Self {
        App { config: None }
    }
}

impl App {
    /// Create an `App` pinned to an explicit [`ServerConfig`].
    ///
    /// All CORS, CSP, and other header settings are taken from `config` rather
    /// than from environment variables. The configuration is fixed for the
    /// lifetime of the `App` instance — SIGHUP / hot-reload do not affect it.
    ///
    /// This is the preferred constructor for integration tests: build a
    /// [`ServerConfig`] with the exact settings under test, pass it here, and
    /// use [`TestClient`] to drive requests. No environment writes and no
    /// [`test_env::lock()`] are needed.
    ///
    /// [`TestClient`]: crate::test_client::TestClient
    /// [`test_env::lock()`]: crate::test_env::lock
    pub fn with_config(config: ServerConfig) -> Self {
        App { config: Some(Arc::new(config)) }
    }

    /// [`App::with_config`] sharing an existing `Arc` instead of copying it.
    pub(crate) fn with_shared_config(config: Arc<ServerConfig>) -> Self {
        App { config: Some(config) }
    }

    /// Whether the built-in controllers answer `request` without blocking:
    /// every GET/HEAD they serve is in memory or a local file read (health,
    /// metrics, assets, static files — large files are only opened here and
    /// streamed from the blocking pool). Uploads and form posts aren't.
    pub(crate) fn is_inline_request(request: &Request) -> bool {
        request.method == crate::request::METHOD.get || request.method == crate::request::METHOD.head
    }
}

impl Application for App {
    // `App` dispatches through a fixed if-chain of built-in `Controller`s
    // rather than a `Router`: the built-in set is small, static, and known
    // at compile time, so a linear scan is simpler and just as fast as a
    // segment-matching router would be here. This is a deliberate choice,
    // not an oversight — `Router` (src/router/mod.rs) is the right tool for
    // user-defined routes with named path params/wildcards, and `AppWithState`
    // / `AsyncAppWithState` use exactly that, falling through to this same
    // controller chain for anything they don't handle themselves.
    fn execute(&self, request: &Request, connection: &ConnectionInfo) -> Result<Response, String> {
        let config = match &self.config {
            Some(c) => Arc::clone(c),
            None => ServerConfig::current(),
        };
        let header_list = Header::get_header_list_with_config(request, &config);
        let response = crate::error::problem::with_headers(
            STATUS_CODE_REASON_PHRASE.n501_not_implemented,
            &format!("no handler for method {}", request.method),
            "",
            Some(header_list),
        );

        let controllers = [
            entry::<IndexController>(),
            entry::<StyleController>(),
            entry::<ScriptController>(),
            entry::<DirectoryListingAssetsController>(),
            entry::<FileUploadInitiateController>(),
            entry::<FormUrlEncodedEnctypePostMethodController>(),
            entry::<FormGetMethodController>(),
            entry::<FormMultipartEnctypePostMethodController>(),
            entry::<HealthController>(),
            entry::<ReadyController>(),
            entry::<MetricsController>(),
            entry::<FaviconController>(),
        ];

        for c in &controllers {
            if (c.is_matching)(request, connection) {
                return Ok((c.process)(request, response, connection));
            }
        }

        // Static files, after every built-in route. A GET/HEAD of a regular
        // file is answered in one pass — StaticResourceController::is_matching
        // would build the path and look the file up, only for process to do
        // both again; serving one implies is_matching would have said yes.
        let mut response = response;
        if let Some(served) = StaticResourceController::serve_regular_file(request, &mut response, &config) {
            return Ok(served);
        }
        if StaticResourceController::is_matching(request, connection)
            && (config.directory_listing || !StaticResourceController::is_directory_without_index(request))
        {
            return Ok(StaticResourceController::process_general(request, response, &config));
        }
        // `/docs/http2/):` — a link copied with the prose around it.
        if let Some(redirect) = StaticResourceController::trailing_punctuation_redirect(request) {
            return Ok(redirect);
        }
        if NotFoundController::is_matching(request, connection) {
            return Ok(NotFoundController::process(request, response, connection));
        }

        Ok(response)
    }

    fn runs_inline(&self, request: &Request, _connection: &ConnectionInfo) -> bool {
        App::is_inline_request(request)
    }
}

impl App {
    /// Dispatch `request` through the controller chain and return the response.
    ///
    /// This is a convenience wrapper over [`Application::execute`] that uses a
    /// synthetic loopback [`ConnectionInfo`]. Use it in tests or when no real
    /// connection context is available. Prefer [`TestClient`] for structured
    /// test code.
    ///
    /// [`TestClient`]: crate::test_client::TestClient
    pub fn handle_request(request: Request) -> (Response, Request) {
        use crate::server::Address;
        let conn = ConnectionInfo {
            client: Address { ip: "127.0.0.1".to_string(), port: 0 },
            server: Address { ip: "127.0.0.1".to_string(), port: 7878 },
            request_size: 16000,
            sni_hostname: None,
            tls: false,
        };
        let app = App::new();
        let response = app.execute(&request, &conn).unwrap_or_else(|_| {
            let header_list = Header::get_header_list_with_config(&request, &ServerConfig::current());
            Response::get_response(
                STATUS_CODE_REASON_PHRASE.n500_internal_server_error,
                Some(header_list),
                None,
            )
        });
        (response, request)
    }

    /// Create a state-aware application. Routes registered on the returned
    /// [`AppWithState<S>`] are tried first; unmatched requests fall through to
    /// the built-in controller chain (static files, health probes, etc.).
    ///
    /// The state is stored as `Arc<S>` and shared across all handlers.
    ///
    /// # Example
    ///
    /// ```rust,no_run
    /// use rust_web_server::app::App;
    /// use rust_web_server::response::{Response, STATUS_CODE_REASON_PHRASE};
    /// use rust_web_server::core::New;
    ///
    /// struct Db { url: String }
    ///
    /// let app = App::with_state(Db { url: "postgres://...".to_string() })
    ///     .get("/ping", |_req, _params, _conn, db| {
    ///         let mut r = Response::new();
    ///         r.status_code = *STATUS_CODE_REASON_PHRASE.n200_ok.status_code;
    ///         r.reason_phrase = STATUS_CODE_REASON_PHRASE.n200_ok.reason_phrase.to_string();
    ///         r
    ///     });
    /// ```
    pub fn with_state<S: Send + Sync + 'static>(state: S) -> AppWithState<S> {
        AppWithState::new(state)
    }

    /// Wrap this application in a middleware layer.
    ///
    /// Returns a [`WithMiddleware<App>`] that runs `layer` before every
    /// request. Chain `.wrap()` calls to stack multiple layers:
    ///
    /// ```rust,no_run
    /// use rust_web_server::app::App;
    /// use rust_web_server::middleware::RateLimitLayer;
    /// use rust_web_server::core::New;
    ///
    /// let app = App::new().wrap(RateLimitLayer);
    /// ```
    pub fn wrap<M: Middleware + 'static>(self, layer: M) -> WithMiddleware<App> {
        WithMiddleware::new(self).wrap(layer)
    }

    /// Attach an MCP server to this application. Tools, resources, and
    /// prompts are registered on the returned [`McpServer`]; requests that
    /// do not match the MCP endpoint are forwarded to `self` (static files,
    /// health probes, any custom routes registered before this call).
    ///
    /// ```rust,no_run
    /// use rust_web_server::app::App;
    /// use rust_web_server::mcp::{McpContent, extract_arg};
    /// use rust_web_server::core::New;
    ///
    /// // Pure MCP — unmatched paths handled by built-in App
    /// let app = App::new()
    ///     .mcp("my-server", "1.0")
    ///     .tool(
    ///         "echo",
    ///         "Echo text back",
    ///         r#"{"type":"object","properties":{"text":{"type":"string"}}}"#,
    ///         |args| Ok(McpContent::text(extract_arg(args, "text").unwrap_or_default())),
    ///     );
    /// ```
    ///
    /// To combine with custom HTTP routes, start from [`App::with_state`]:
    ///
    /// ```rust,no_run
    /// use rust_web_server::app::App;
    /// use rust_web_server::mcp::McpContent;
    /// use rust_web_server::response::{Response, STATUS_CODE_REASON_PHRASE};
    /// use rust_web_server::core::New;
    ///
    /// let app = App::with_state(())
    ///     .get("/api/ping", |_, _, _, _| {
    ///         let mut r = Response::new();
    ///         r.status_code = *STATUS_CODE_REASON_PHRASE.n200_ok.status_code;
    ///         r.reason_phrase = STATUS_CODE_REASON_PHRASE.n200_ok.reason_phrase.to_string();
    ///         r
    ///     })
    ///     .mcp("my-server", "1.0")
    ///     .tool("ping", "Ping the server", "{}", |_| Ok(McpContent::text("pong")));
    /// ```
    pub fn mcp(self, name: impl Into<String>, version: impl Into<String>) -> McpServer {
        McpServer::new(name, version).wrap(self)
    }

    /// Create an async state-aware application (requires the `http2` feature).
    ///
    /// Handlers are `async fn` closures that can `await` database queries,
    /// HTTP clients, or any other async I/O. Unmatched routes fall through to
    /// the built-in controller chain.
    ///
    /// # Example
    ///
    /// ```rust,no_run
    /// use std::sync::Arc;
    /// use rust_web_server::app::App;
    /// use rust_web_server::response::{Response, STATUS_CODE_REASON_PHRASE};
    /// use rust_web_server::core::New;
    ///
    /// struct Db { url: String }
    ///
    /// let app = App::with_async_state(Db { url: "postgres://...".to_string() })
    ///     .get("/ping", |_req, _params, _conn, state| async move {
    ///         // state: Arc<Db>
    ///         let mut r = Response::new();
    ///         r.status_code = *STATUS_CODE_REASON_PHRASE.n200_ok.status_code;
    ///         r.reason_phrase = STATUS_CODE_REASON_PHRASE.n200_ok.reason_phrase.to_string();
    ///         r
    ///     });
    /// ```
    #[cfg(feature = "http2")]
    pub fn with_async_state<S: Send + Sync + 'static>(state: S) -> crate::async_state::AsyncAppWithState<S> {
        crate::async_state::AsyncAppWithState::new(state)
    }
}