Add a directory listing feature for file URLs (#32580)

Signed-off-by: Bobulous <Bobulous@users.noreply.github.com>
Signed-off-by: Martin Robinson <mrobinson@igalia.com>
Co-authored-by: Bobulous <Bobulous@users.noreply.github.com>

Cargo.lock

@@ -4061,6 +4061,7 @@ dependencies = [
  "base64",
  "brotli",
  "bytes",
+ "chrono",
  "content-security-policy",
  "cookie 0.12.0",
  "crossbeam-channel",

Cargo.toml

@@ -30,6 +30,7 @@ bluetooth_traits = { path = "components/shared/bluetooth" }
 byteorder = "1.5"
 canvas_traits = { path = "components/shared/canvas" }
 cfg-if = "1.0.0"
+chrono = "0.4"
 compositing_traits = { path = "components/shared/compositing" }
 content-security-policy = { version = "0.5", features = ["serde"] }
 cookie = "0.12"

components/config/prefs.rs

@@ -551,6 +551,9 @@ mod gen {
                     #[serde(rename = "network.http-cache.disabled")]
                     disabled: bool,
                 },
+                local_directory_listing: {
+                    enabled: bool,
+                },
                 mime: {
                     sniff: bool,
                 }

components/devtools/Cargo.toml

@@ -11,11 +11,11 @@ name = "devtools"
 path = "lib.rs"
 
 [build-dependencies]
-chrono = "0.4"
+chrono = { workspace = true }
 
 [dependencies]
 base = { workspace = true }
-chrono = "0.4"
+chrono = { workspace = true }
 crossbeam-channel = { workspace = true }
 devtools_traits = { workspace = true }
 embedder_traits = { workspace = true }

components/net/Cargo.toml

@@ -58,6 +58,7 @@ servo_config = { path = "../config" }
 servo_url = { path = "../url" }
 sha2 = "0.10"
 time = { workspace = true }
+chrono = { workspace = true }
 tokio = { workspace = true, features = ["sync", "macros", "rt-multi-thread"] }
 tokio-rustls = { workspace = true }
 tokio-stream = "0.1"

components/net/fetch/methods.rs

@@ -50,6 +50,7 @@ use crate::http_loader::{
     determine_requests_referrer, http_fetch, set_default_accept, set_default_accept_language,
     HttpState,
 };
+use crate::local_directory_listing;
 use crate::subresource_integrity::is_response_integrity_valid;
 
 lazy_static! {
@@ -729,15 +730,11 @@ async fn scheme_fetch(
                 ));
             }
             if let Ok(file_path) = url.to_file_path() {
-                if let Ok(file) = File::open(file_path.clone()) {
-                    if let Ok(metadata) = file.metadata() {
-                        if metadata.is_dir() {
-                            return Response::network_error(NetworkError::Internal(
-                                "Opening a directory is not supported".into(),
-                            ));
-                        }
-                    }
+                if file_path.is_dir() {
+                    return local_directory_listing::fetch(request, url, file_path);
+                }
 
+                if let Ok(file) = File::open(file_path.clone()) {
                     // Get range bounds (if any) and try to seek to the requested offset.
                     // If seeking fails, bail out with a NetworkError.
                     let file_size = match file.metadata() {

components/net/lib.rs

@@ -16,6 +16,7 @@ pub mod hsts;
 pub mod http_cache;
 pub mod http_loader;
 pub mod image_cache;
+pub mod local_directory_listing;
 pub mod mime_classifier;
 pub mod resource_thread;
 mod storage_thread;

components/net/local_directory_listing.rs

@@ -0,0 +1,158 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+use std::fs::{DirEntry, Metadata, ReadDir};
+use std::path::PathBuf;
+
+use chrono::{DateTime, Local};
+use embedder_traits::resources::{read_string, Resource};
+use headers::{ContentType, HeaderMapExt};
+use net_traits::request::Request;
+use net_traits::response::{Response, ResponseBody};
+use net_traits::{NetworkError, ResourceFetchTiming};
+use servo_config::pref;
+use servo_url::ServoUrl;
+use url::Url;
+
+pub fn fetch(request: &mut Request, url: ServoUrl, path_buf: PathBuf) -> Response {
+    if !pref!(network.local_directory_listing.enabled) {
+        // If you want to be able to browse local directories, configure Servo prefs so that
+        // "network.local_directory_listing.enabled" is set to true.
+        return Response::network_error(NetworkError::Internal(
+            "Local directory listing feature has not been enabled in preferences".into(),
+        ));
+    }
+
+    if !request.origin.is_opaque() {
+        // Checking for an opaque origin as a shorthand for user activation
+        // as opposed to a request originating from a script.
+        // TODO(32534): carefully consider security of this approach.
+        return Response::network_error(NetworkError::Internal(
+            "Cannot request local directory listing from non-local origin.".into(),
+        ));
+    }
+
+    let directory_contents = match std::fs::read_dir(path_buf.clone()) {
+        Ok(directory_contents) => directory_contents,
+        Err(error) => {
+            return Response::network_error(NetworkError::Internal(format!(
+                "Unable to access directory: {error}"
+            )));
+        },
+    };
+
+    let output = build_html_directory_listing(url.as_url(), path_buf, directory_contents);
+
+    let mut response = Response::new(url, ResourceFetchTiming::new(request.timing_type()));
+    response.headers.typed_insert(ContentType::html());
+    *response.body.lock().unwrap() = ResponseBody::Done(output.into_bytes());
+
+    response
+}
+
+/// Returns an the string of an JavaScript `<script>` tag calling the `setData` function with the
+/// contents of the given [`ReadDir`] directory listing.
+///
+/// # Arguments
+///
+/// * `url` - the original URL of the request that triggered this directory listing.
+/// * `path` - the full path to the local directory.
+/// * `directory_contents` - a [`ReadDir`] with the contents of the directory.
+pub fn build_html_directory_listing(
+    url: &Url,
+    path: PathBuf,
+    directory_contents: ReadDir,
+) -> String {
+    let mut page_html = String::with_capacity(1024);
+    page_html.push_str("<!DOCTYPE html>");
+
+    let mut parent_url_string = String::new();
+    if path.parent().is_some() {
+        let mut parent_url = url.clone();
+        if let Ok(mut path_segments) = parent_url.path_segments_mut() {
+            path_segments.pop();
+        }
+        parent_url_string = parent_url.as_str().to_owned();
+    }
+
+    page_html.push_str(&read_string(Resource::DirectoryListingHTML));
+
+    page_html.push_str("<script>\n");
+    page_html.push_str(&format!(
+        "setData({:?}, {:?}, [",
+        url.as_str(),
+        parent_url_string
+    ));
+
+    for directory_entry in directory_contents {
+        let Ok(directory_entry) = directory_entry else {
+            continue;
+        };
+        let Ok(metadata) = directory_entry.metadata() else {
+            continue;
+        };
+        write_directory_entry(directory_entry, metadata, url, &mut page_html);
+    }
+
+    page_html.push_str("]);");
+    page_html.push_str("</script>\n");
+
+    page_html
+}
+
+fn write_directory_entry(entry: DirEntry, metadata: Metadata, url: &Url, output: &mut String) {
+    let Ok(name) = entry.file_name().into_string() else {
+        return;
+    };
+
+    let mut file_url = url.clone();
+    {
+        let Ok(mut path_segments) = file_url.path_segments_mut() else {
+            return;
+        };
+        path_segments.push(&name);
+    }
+
+    let class = if metadata.is_dir() {
+        "directory"
+    } else if metadata.is_symlink() {
+        "symlink"
+    } else {
+        "file"
+    };
+
+    let file_url_string = &file_url.to_string();
+    let file_size = metadata_to_file_size_string(&metadata);
+    let last_modified = metadata
+        .modified()
+        .map(|time| DateTime::<Local>::from(time))
+        .map(|time| time.format("%F %r").to_string())
+        .unwrap_or_default();
+
+    output.push_str(&format!(
+        "[{class:?}, {name:?}, {file_url_string:?}, {file_size:?}, {last_modified:?}],"
+    ));
+}
+
+pub fn metadata_to_file_size_string(metadata: &Metadata) -> String {
+    if !metadata.is_file() {
+        return String::new();
+    }
+
+    let mut float_size = metadata.len() as f64;
+    let mut prefix_power = 0;
+    while float_size > 1000.0 && prefix_power < 3 {
+        float_size /= 1000.0;
+        prefix_power += 1;
+    }
+
+    let prefix = match prefix_power {
+        0 => "B",
+        1 => "KB",
+        2 => "MB",
+        _ => "GB",
+    };
+
+    return format!("{:.2} {prefix}", float_size);
+}

components/script/Cargo.toml

@@ -37,7 +37,7 @@ base64 = { workspace = true }
 bitflags = { workspace = true }
 bluetooth_traits = { workspace = true }
 canvas_traits = { workspace = true }
-chrono = "0.4"
+chrono = { workspace = true }
 content-security-policy = { workspace = true }
 cookie = { workspace = true }
 crossbeam-channel = { workspace = true }

components/shared/embedder/resources.rs

@@ -71,6 +71,7 @@ pub enum Resource {
     MediaControlsCSS,
     MediaControlsJS,
     CrashHTML,
+    DirectoryListingHTML,
 }
 
 impl Resource {
@@ -90,6 +91,7 @@ impl Resource {
             Resource::MediaControlsCSS => "media-controls.css",
             Resource::MediaControlsJS => "media-controls.js",
             Resource::CrashHTML => "crash.html",
+            Resource::DirectoryListingHTML => "directory-listing.html",
         }
     }
 }
@@ -146,6 +148,9 @@ fn resources_for_tests() -> Box<dyn ResourceReaderMethods + Sync + Send> {
                     &include_bytes!("../../../resources/media-controls.js")[..]
                 },
                 Resource::CrashHTML => &include_bytes!("../../../resources/crash.html")[..],
+                Resource::DirectoryListingHTML => {
+                    &include_bytes!("../../../resources/directory-listing.html")[..]
+                },
             }
             .to_owned()
         }

components/shared/net/request.rs

@@ -37,6 +37,12 @@ pub enum Origin {
     Origin(ImmutableOrigin),
 }
 
+impl Origin {
+    pub fn is_opaque(&self) -> bool {
+        matches!(self, Origin::Origin(ImmutableOrigin::Opaque(_)))
+    }
+}
+
 /// A [referer](https://fetch.spec.whatwg.org/#concept-request-referrer)
 #[derive(Clone, Debug, Deserialize, MallocSizeOf, PartialEq, Serialize)]
 pub enum Referrer {

ports/servoshell/egl/android/simpleservo.rs

@@ -931,6 +931,9 @@ impl ResourceReaderMethods for ResourceReaderInstance {
                 &include_bytes!("../../../../resources/media-controls.js")[..]
             },
             Resource::CrashHTML => &include_bytes!("../../../../resources/crash.html")[..],
+            Resource::DirectoryListingHTML => {
+                &include_bytes!("../../../../resources/directory-listing.html")[..]
+            },
         })
     }
 

resources/directory-listing.html

@@ -0,0 +1,103 @@
+<!DOCTYPE html>
+<html>
+    <head>
+        <title>Index of</title>
+        <style>
+            h1 {
+                border-bottom: 1px solid black;
+            }
+
+            .listing {
+                margin: 0.5em;
+                display: table;
+            }
+
+            .listing .header,
+            .listing .entry {
+                display: table-row;
+            }
+
+            .listing .header {
+                font-weight: bold;
+            }
+
+            .listing .header span,
+            .listing .entry span {
+                display: table-cell;
+                padding-right: 1em;
+            }
+
+            .entry span:nth-child(1) {
+                min-width: 20em;
+            }
+
+            .entry span.size,
+            .entry span.last-modified {
+                white-space: nowrap;
+            }
+
+            .parent_link > a:before {
+                content: "📁 ";
+            }
+
+            .parent_link {
+                display: none;
+            }
+
+            .entry.directory > .name:before {
+                content: "📁 ";
+            }
+
+            .entry.file > .name:before {
+                content: "📄 ";
+            }
+
+            .entry.symlink > .name:before {
+                content: "🔗 ";
+            }
+        </style>
+        <script>
+            function setData(directoryName, parentLink, rows) {
+                document.title += directoryName;
+                document.querySelector("h1").innerHTML += " " + directoryName;
+
+                if (parentLink != "") {
+                    document.querySelector(".parent_link > a").href = parentLink;
+                    document.querySelector(".parent_link").style.display = "initial";
+                }
+
+                rows.sort((rowA, rowB) => rowA[1].localeCompare(rowB[1]));
+
+                let listing = document.querySelector(".listing");
+                let rowTemplate = document.getElementById("rowTemplate");
+                for (row of rows) {
+                    let rowElement = rowTemplate.content.cloneNode(true);
+                    rowElement.querySelector(".entry").classList.add(row[0]);
+                    rowElement.querySelector(".name > .link").innerText = row[1];
+                    rowElement.querySelector(".name > .link").href = row[2];
+                    rowElement.querySelector(".size").innerText = row[3];
+                    rowElement.querySelector(".last-modified").innerText = row[4];
+                    listing.appendChild(rowElement);
+                }
+            }
+        </script>
+    </head>
+    <body>
+        <h1>Index of</h1>
+        <div class="parent_link"><a href="">Up to parent directory</a></div>
+        <div class="listing">
+            <div class="header">
+                <span class="name">Name</span>
+                <span class="size">Size</span>
+                <span class="last-modified">Last Modified</span>
+            </div>
+        </div>
+        <template id="rowTemplate">
+            <div class="entry">
+                <span class="name"><a class="link"></a></span>
+                <span class="size"></span>
+                <span class="last-modified"></span>
+            </div>
+        </template>
+    </body>
+</html>

resources/prefs.json

@@ -111,6 +111,7 @@
   "network.enforce_tls.localhost": false,
   "network.enforce_tls.onion": false,
   "network.http-cache.disabled": false,
+  "network.local_directory_listing.enabled": false,
   "network.mime.sniff": false,
   "session-history.max-length": 20,
   "shell.background-color.rgba": [1.0, 1.0, 1.0, 1.0],