rama_http/service/fs/serve_dir/

mod.rs

use crate::headers::encoding::{SupportedEncodings, parse_accept_encoding_headers};
use crate::layer::set_status::SetStatus;
use crate::mime::Mime;
use crate::service::web::response::IntoResponse;
use crate::{Body, Method, Request, Response, StatusCode, StreamingBody, header};
use rama_core::Service;
use rama_core::bytes::Bytes;
use rama_core::error::BoxError;
use rama_core::error::BoxErrorExt as _;
use rama_core::telemetry::tracing;
use rama_net::uri::util::percent_encoding::percent_decode;
use rama_utils::include_dir::Dir;
use std::fmt;
use std::str::FromStr;
use std::{
    convert::Infallible,
    path::{Path, PathBuf},
};

pub(crate) mod future;
mod headers;
mod open_file;

#[cfg(test)]
mod tests;

/// Source of directory content - either filesystem or embedded.
#[derive(Clone, Debug)]
enum DirSource {
    Filesystem(PathBuf),
    Embedded(Dir<'static>),
}

// default capacity 64KiB
const DEFAULT_CAPACITY: usize = 65536;

/// Service that serves files from a given directory and all its sub directories.
///
/// The `Content-Type` will be guessed from the file extension.
///
/// An empty response with status `404 Not Found` will be returned if:
///
/// - The file doesn't exist
/// - Any segment of the path contains `..`
/// - Any segment of the path contains a backslash
/// - On unix, any segment of the path referenced as directory is actually an
///   existing file (`/file.html/something`)
/// - We don't have necessary permissions to read the file
#[derive(Clone, Debug)]
pub struct ServeDir<F = DefaultServeDirFallback> {
    base: DirSource,
    buf_chunk_size: usize,
    symlink_policy: ServeDirSymlinkPolicy,
    precompressed_variants: Option<PrecompressedVariants>,
    // This is used to specialise implementation for
    // single files
    variant: ServeVariant,
    fallback: Option<F>,
    call_fallback_on_method_not_allowed: bool,
}

impl ServeDir<DefaultServeDirFallback> {
    /// Create a new [`ServeDir`].
    pub fn new<P>(path: P) -> Self
    where
        P: AsRef<Path>,
    {
        let mut base = PathBuf::from(".");
        base.push(path.as_ref());

        Self::new_with_base(DirSource::Filesystem(base))
    }

    /// Create a new [`ServeDir`] that serves files from embedded content.
    #[must_use]
    pub fn new_embedded(path: Dir<'static>) -> Self {
        Self::new_with_base(DirSource::Embedded(path))
    }

    /// Create a new [`ServeDir`] with the specified directory source and default settings.
    fn new_with_base(base: DirSource) -> Self {
        Self {
            base,
            buf_chunk_size: DEFAULT_CAPACITY,
            symlink_policy: ServeDirSymlinkPolicy::default(),
            precompressed_variants: None,
            variant: ServeVariant::Directory {
                serve_mode: Default::default(),
                html_as_default_extension: false,
            },
            fallback: None,
            call_fallback_on_method_not_allowed: false,
        }
    }

    /// Create a new [`ServeDir`] configured to serve a single file.
    pub(crate) fn new_single_file<P>(path: P, mime: Mime) -> Self
    where
        P: AsRef<Path>,
    {
        Self {
            base: DirSource::Filesystem(path.as_ref().to_path_buf()),
            buf_chunk_size: DEFAULT_CAPACITY,
            symlink_policy: ServeDirSymlinkPolicy::default(),
            precompressed_variants: None,
            variant: ServeVariant::SingleFile { mime },
            fallback: None,
            call_fallback_on_method_not_allowed: false,
        }
    }
}

impl<F> ServeDir<F> {
    rama_utils::macros::generate_set_and_with! {
        /// Set the [`DirectoryServeMode`].
        pub fn directory_serve_mode(mut self, mode: DirectoryServeMode) -> Self {
            match &mut self.variant {
                ServeVariant::Directory { serve_mode, .. } => {
                    *serve_mode = mode;
                    self
                }
                ServeVariant::SingleFile { mime: _ } => self,
            }
        }
    }

    rama_utils::macros::generate_set_and_with! {
        /// If the requested path doesn't specify a file extension, append `.html`
        /// to it before trying to open it. Useful for serving static sites that
        /// link to bare filenames (e.g. `/about` → `/about.html`).
        ///
        /// Has no effect for [`ServeFile`](super::ServeFile) (single-file mode).
        ///
        /// Defaults to `false`.
        pub fn html_as_default_extension(mut self, html_as_default_extension: bool) -> Self {
            match &mut self.variant {
                ServeVariant::Directory { html_as_default_extension: dst, .. } => {
                    *dst = html_as_default_extension;
                    self
                }
                ServeVariant::SingleFile { mime: _ } => self,
            }
        }
    }

    rama_utils::macros::generate_set_and_with! {
        /// Set a specific read buffer chunk size.
        ///
        /// The default capacity is 64kb.
        pub fn buf_chunk_size(mut self, chunk_size: usize) -> Self {
            self.buf_chunk_size = chunk_size;
            self
        }
    }

    rama_utils::macros::generate_set_and_with! {
        /// Set the filesystem symlink policy.
        ///
        /// Defaults to [`ServeDirSymlinkPolicy::RejectAll`].
        /// This only applies to filesystem-backed services; embedded services
        /// do not resolve filesystem symlinks.
        pub fn symlink_policy(mut self, policy: ServeDirSymlinkPolicy) -> Self {
            self.symlink_policy = policy;
            self
        }
    }

    rama_utils::macros::generate_set_and_with! {
        /// Informs the service that it should also look for a precompressed gzip
        /// version of _any_ file in the directory.
        ///
        /// Assuming the `dir` directory is being served and `dir/foo.txt` is requested,
        /// a client with an `Accept-Encoding` header that allows the gzip encoding
        /// will receive the file `dir/foo.txt.gz` instead of `dir/foo.txt`.
        /// If the precompressed file is not available, or the client doesn't support it,
        /// the uncompressed version will be served instead.
        /// Both the precompressed version and the uncompressed version are expected
        /// to be present in the directory. Different precompressed variants can be combined.
        pub fn precompressed_gzip(mut self) -> Self {
            self.precompressed_variants
                .get_or_insert(Default::default())
                .gzip = true;
            self
        }
    }

    rama_utils::macros::generate_set_and_with! {
        /// Informs the service that it should also look for a precompressed brotli
        /// version of _any_ file in the directory.
        ///
        /// Assuming the `dir` directory is being served and `dir/foo.txt` is requested,
        /// a client with an `Accept-Encoding` header that allows the brotli encoding
        /// will receive the file `dir/foo.txt.br` instead of `dir/foo.txt`.
        /// If the precompressed file is not available, or the client doesn't support it,
        /// the uncompressed version will be served instead.
        /// Both the precompressed version and the uncompressed version are expected
        /// to be present in the directory. Different precompressed variants can be combined.
        pub fn precompressed_br(mut self) -> Self {
            self.precompressed_variants
                .get_or_insert_default()
                .br = true;
            self
        }
    }

    rama_utils::macros::generate_set_and_with! {
        /// Informs the service that it should also look for a precompressed deflate
        /// version of _any_ file in the directory.
        ///
        /// Assuming the `dir` directory is being served and `dir/foo.txt` is requested,
        /// a client with an `Accept-Encoding` header that allows the deflate encoding
        /// will receive the file `dir/foo.txt.zz` instead of `dir/foo.txt`.
        /// If the precompressed file is not available, or the client doesn't support it,
        /// the uncompressed version will be served instead.
        /// Both the precompressed version and the uncompressed version are expected
        /// to be present in the directory. Different precompressed variants can be combined.
        pub fn precompressed_deflate(mut self) -> Self {
            self.precompressed_variants
                .get_or_insert_default()
                .deflate = true;
            self
        }
    }

    rama_utils::macros::generate_set_and_with! {
        /// Informs the service that it should also look for a precompressed zstd
        /// version of _any_ file in the directory.
        ///
        /// Assuming the `dir` directory is being served and `dir/foo.txt` is requested,
        /// a client with an `Accept-Encoding` header that allows the zstd encoding
        /// will receive the file `dir/foo.txt.zst` instead of `dir/foo.txt`.
        /// If the precompressed file is not available, or the client doesn't support it,
        /// the uncompressed version will be served instead.
        /// Both the precompressed version and the uncompressed version are expected
        /// to be present in the directory. Different precompressed variants can be combined.
        pub fn precompressed_zstd(mut self) -> Self {
            self.precompressed_variants
                .get_or_insert_default()
                .zstd = true;
            self
        }
    }

    /// Set the fallback service.
    ///
    /// This service will be called if there is no file at the path of the request.
    ///
    /// The status code returned by the fallback will not be altered. Use
    /// [`ServeDir::not_found_service`] to set a fallback and always respond with `404 Not Found`.
    pub fn fallback<F2>(self, new_fallback: F2) -> ServeDir<F2> {
        ServeDir {
            base: self.base,
            buf_chunk_size: self.buf_chunk_size,
            symlink_policy: self.symlink_policy,
            precompressed_variants: self.precompressed_variants,
            variant: self.variant,
            fallback: Some(new_fallback),
            call_fallback_on_method_not_allowed: self.call_fallback_on_method_not_allowed,
        }
    }

    /// Set the fallback service and override the fallback's status code to `404 Not Found`.
    ///
    /// This service will be called if there is no file at the path of the request.
    #[must_use]
    pub fn not_found_service<F2>(self, new_fallback: F2) -> ServeDir<SetStatus<F2>> {
        self.fallback(SetStatus::new(new_fallback, StatusCode::NOT_FOUND))
    }

    rama_utils::macros::generate_set_and_with! {
        /// Customize whether or not to call the fallback for requests that aren't `GET` or `HEAD`.
        ///
        /// Defaults to not calling the fallback and instead returning `405 Method Not Allowed`.
        pub fn call_fallback_on_method_not_allowed(mut self, call_fallback: bool) -> Self {
            self.call_fallback_on_method_not_allowed = call_fallback;
            self
        }
    }

    /// Call the service and get a future that contains any `std::io::Error` that might have
    /// happened.
    ///
    /// By default `<ServeDir as Service<_>>::call` will handle IO errors and convert them into
    /// responses. It does that by converting [`std::io::ErrorKind::NotFound`] and
    /// [`std::io::ErrorKind::PermissionDenied`] to `404 Not Found` and any other error to `500
    /// Internal Server Error`. The error will also be logged with `tracing`.
    ///
    /// If you want to manually control how the error response is generated you can make a new
    /// service that wraps a `ServeDir` and calls `try_call` instead of `call`.
    pub async fn try_call<ReqBody, FResBody>(
        &self,
        req: Request<ReqBody>,
    ) -> Result<Response, std::io::Error>
    where
        F: Service<Request<ReqBody>, Output = Response<FResBody>, Error = Infallible> + Clone,
        FResBody: StreamingBody<Data = Bytes, Error: Into<BoxError>> + Send + Sync + 'static,
    {
        if req.method() != Method::GET && req.method() != Method::HEAD {
            if self.call_fallback_on_method_not_allowed
                && let Some(fallback) = self.fallback.as_ref()
            {
                return future::serve_fallback(fallback, req).await;
            }

            return Ok(future::method_not_allowed());
        }

        // `ServeDir` doesn't care about the request body but the fallback might. So move out the
        // body and pass it to the fallback, leaving an empty body in its place
        //
        // this is necessary because we cannot clone bodies
        let (mut parts, body) = req.into_parts();
        // same goes for extensions
        let extensions = std::mem::take(&mut parts.extensions);
        let req = Request::from_parts(parts, Body::empty());

        let fallback_and_request = self.fallback.as_ref().map(|fallback| {
            let mut fallback_req = Request::new(body);
            *fallback_req.method_mut() = req.method().clone();
            *fallback_req.uri_mut() = req.uri().clone();
            *fallback_req.headers_mut() = req.headers().clone();
            // Carry the ORIGINAL request's full extensions (including any
            // parent chain) onto the fallback request. `extend` would copy
            // only the top-level store and silently drop a parent chain.
            let (mut fallback_parts, fallback_body) = fallback_req.into_parts();
            fallback_parts.extensions = extensions;
            let fallback_req = Request::from_parts(fallback_parts, fallback_body);

            (fallback, fallback_req)
        });

        // Canonicalize per RFC 3986 first so `.`/`..` segments (including
        // percent-encoded ones) are resolved and clamped to the path root
        // before mapping to the filesystem; `build_and_validate_path` then
        // rejects anything that survives as a defensive backstop.
        let canonical_uri = req.uri().clone().canonicalize();

        let requested_path = canonical_uri.path_or_root();
        let Some(path_to_file) = self
            .variant
            .build_and_validate_path(&self.base, requested_path.as_ref())
        else {
            return if let Some((fallback, request)) = fallback_and_request {
                future::serve_fallback(fallback, request).await
            } else {
                Ok(future::not_found())
            };
        };

        let buf_chunk_size = self.buf_chunk_size;
        let range_header = req
            .headers()
            .get(header::RANGE)
            .and_then(|value| value.to_str().ok())
            .map(|s| s.to_owned());

        let precompression_configured = self.precompressed_variants.is_some();
        let negotiated_encodings: Vec<_> = parse_accept_encoding_headers(
            req.headers(),
            self.precompressed_variants.unwrap_or_default(),
        )
        .collect();

        let variant = self.variant.clone();
        let open_file_result = open_file::open_file(
            variant,
            path_to_file,
            req,
            negotiated_encodings,
            range_header.as_deref(),
            buf_chunk_size,
            &self.base,
            precompression_configured,
            self.symlink_policy,
        )
        .await;

        future::consume_open_file_result(open_file_result, fallback_and_request).await
    }
}

impl<ReqBody, F, FResBody> Service<Request<ReqBody>> for ServeDir<F>
where
    ReqBody: Send + 'static,
    F: Service<Request<ReqBody>, Output = Response<FResBody>, Error = Infallible> + Clone,
    FResBody: StreamingBody<Data = Bytes, Error: Into<BoxError>> + Send + Sync + 'static,
{
    type Output = Response;
    type Error = Infallible;

    async fn serve(&self, req: Request<ReqBody>) -> Result<Self::Output, Self::Error> {
        let result = self.try_call(req).await;
        Ok(result.unwrap_or_else(|err| {
            tracing::error!("Failed to read file: {err:?}");
            StatusCode::INTERNAL_SERVER_ERROR.into_response()
        }))
    }
}

/// Controls whether [`ServeDir`]/[`ServeFile`](super::ServeFile) follow filesystem
/// symlinks when resolving a requested path.
///
/// The policy governs the **request-supplied** path components below the
/// configured root: those are the path-traversal escape vector. The configured
/// root (or single-file target) is operator-trusted and is served even if it is
/// itself a symlink (e.g. a blue-green `current -> releases/N` deploy).
///
/// # Security caveat
///
/// Symlink rejection is **best-effort**: it is enforced by stat-ing each path
/// component and then opening the file, which is two separate resolutions
/// (a TOCTOU window). If the served tree is writable by untrusted parties a
/// component could be swapped for a symlink between the check and the open.
/// `RejectAll` is therefore not a substitute for serving from a root that is
/// not writable by untrusted parties.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
pub enum ServeDirSymlinkPolicy {
    #[default]
    /// Reject any requested path component that is a symlink (final or intermediate).
    RejectAll,
    /// Allow the final requested path component to be a symlink, but reject symlinked
    /// intermediate directory components.
    AllowFinalComponent,
    /// Allow filesystem symlinks. This restores the historical follow-symlinks behavior.
    AllowAll,
}

impl fmt::Display for ServeDirSymlinkPolicy {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(
            f,
            "{}",
            match self {
                Self::RejectAll => "reject-all",
                Self::AllowFinalComponent => "allow-final-component",
                Self::AllowAll => "allow-all",
            }
        )
    }
}

impl FromStr for ServeDirSymlinkPolicy {
    type Err = BoxError;

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        rama_utils::macros::match_ignore_ascii_case_str! {
            match(s) {
                "reject-all" | "reject_all" => Ok(Self::RejectAll),
                "allow-final-component" | "allow_final_component" => Ok(Self::AllowFinalComponent),
                "allow-all" | "allow_all" => Ok(Self::AllowAll),
                _ => Err(BoxError::from_static_str("invalid ServeDirSymlinkPolicy str")),
            }
        }
    }
}

impl TryFrom<&str> for ServeDirSymlinkPolicy {
    type Error = BoxError;

    #[inline]
    fn try_from(value: &str) -> Result<Self, Self::Error> {
        value.parse()
    }
}

#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
pub enum DirectoryServeMode {
    #[default]
    /// If the requested path is a directory append `index.html`.
    ///
    /// This is useful for static sites
    AppendIndexHtml,
    /// If the requested path is a directory
    /// handle it as resource "not found" (404).
    NotFound,
    /// Show the file tree of the directory as file tree
    /// which can be navigated.
    #[cfg(feature = "html")]
    HtmlFileList,
}

impl fmt::Display for DirectoryServeMode {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(
            f,
            "{}",
            match self {
                Self::AppendIndexHtml => "append-index",
                Self::NotFound => "not-found",
                #[cfg(feature = "html")]
                Self::HtmlFileList => "html-file-list",
            }
        )
    }
}

impl FromStr for DirectoryServeMode {
    type Err = BoxError;

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        rama_utils::macros::match_ignore_ascii_case_str! {
            match(s) {
                "append-index" | "append_index" => Ok(Self::AppendIndexHtml),
                "not-found" | "not_found" => Ok(Self::NotFound),
                "html-file-list" | "html_file_list" => html_file_list_from_str(),
                _ => Err(BoxError::from_static_str("invalid DirectoryServeMode str")),
            }
        }
    }
}

#[inline(always)]
fn html_file_list_from_str() -> Result<DirectoryServeMode, BoxError> {
    #[cfg(feature = "html")]
    {
        Ok(DirectoryServeMode::HtmlFileList)
    }
    #[cfg(not(feature = "html"))]
    {
        Err(BoxError::from_static_str(
            "invalid DirectoryServeMode str: html file list requires html feature",
        ))
    }
}

impl TryFrom<&str> for DirectoryServeMode {
    type Error = BoxError;

    #[inline]
    fn try_from(value: &str) -> Result<Self, Self::Error> {
        value.parse()
    }
}

// Allow the ServeDir service to be used in the ServeFile service
// with almost no overhead
#[derive(Clone, Debug)]
enum ServeVariant {
    Directory {
        serve_mode: DirectoryServeMode,
        /// If true, requests for a path without a file extension that doesn't
        /// resolve to anything will be retried with `.html` appended.
        html_as_default_extension: bool,
    },
    SingleFile {
        mime: Mime,
    },
}

impl ServeVariant {
    /// Build and validate the file path based on the serve variant and requested path.
    /// Returns None if the path is invalid or unsafe.
    fn build_and_validate_path(&self, source: &DirSource, requested_path: &str) -> Option<PathBuf> {
        match self {
            Self::Directory { .. } => {
                let path = requested_path.trim_start_matches('/');

                let path_decoded = percent_decode(path.as_ref()).decode_utf8().ok()?;

                // Reject path-traversal (`..`), absolute paths, smuggled
                // prefixes (`/foo/c:/bar`, #204) and reserved device names via
                // the shared utils primitive, then map the cleaned relative path
                // under the configured root.
                let relative = rama_utils::fs::sanitize_relative_path(&*path_decoded).ok()?;

                let mut path_to_file = match source {
                    DirSource::Filesystem(base_path) => base_path.clone(),
                    DirSource::Embedded(_) => PathBuf::new(), // For embedded files, we don't need a filesystem path
                };
                path_to_file.push(relative);
                Some(path_to_file)
            }
            Self::SingleFile { mime: _ } => match source {
                DirSource::Filesystem(base_path) => Some(base_path.clone()),
                DirSource::Embedded(_) => Some(PathBuf::new()), // For embedded single file
            },
        }
    }
}

/// The default fallback service used with [`ServeDir`].
#[derive(Debug, Clone, Copy)]
pub struct DefaultServeDirFallback(Infallible);

impl<ReqBody> Service<Request<ReqBody>> for DefaultServeDirFallback
where
    ReqBody: Send + 'static,
{
    type Output = Response;
    type Error = Infallible;

    async fn serve(&self, _req: Request<ReqBody>) -> Result<Self::Output, Self::Error> {
        match self.0 {}
    }
}

#[derive(Clone, Copy, Debug, Default)]
struct PrecompressedVariants {
    gzip: bool,
    deflate: bool,
    br: bool,
    zstd: bool,
}

impl SupportedEncodings for PrecompressedVariants {
    fn gzip(&self) -> bool {
        self.gzip
    }

    fn deflate(&self) -> bool {
        self.deflate
    }

    fn br(&self) -> bool {
        self.br
    }

    fn zstd(&self) -> bool {
        self.zstd
    }
}