Validate WebDAV connections and match directory responses by path

Cargo.lock

@@ -99,9 +99,16 @@ name = "memona-plugin-webdav"
 version = "0.1.1"
 dependencies = [
  "quick-xml",
+ "tokio",
  "wit-bindgen",
 ]
 
+[[package]]
+name = "pin-project-lite"
+version = "0.2.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a89322df9ebe1c1578d689c92318e070967d1042b512afbe49518723f4e6d5cd"
+
 [[package]]
 name = "prettyplease"
 version = "0.3.0"
@@ -198,6 +205,27 @@ dependencies = [
  "unicode-ident",
 ]
 
+[[package]]
+name = "tokio"
+version = "1.53.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "202caea871b69668250d242070849eb495be178ed697a3e98aebce5bc81a0bed"
+dependencies = [
+ "pin-project-lite",
+ "tokio-macros",
+]
+
+[[package]]
+name = "tokio-macros"
+version = "2.7.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "78773a2a397f451582ce068015985c33193cf6dea8b74d2a639fe457b2f07b0e"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "unicode-ident"
 version = "1.0.26"

Cargo.toml

@@ -13,6 +13,9 @@ crate-type = ["cdylib", "rlib"]
 wit-bindgen = "=0.62.0"
 quick-xml = { version = "0.37", default-features = false }
 
+[target.'cfg(not(target_arch = "wasm32"))'.dev-dependencies]
+tokio = { version = "1", features = ["macros", "rt"] }
+
 [lints.clippy]
 panic = "deny"
 unwrap_used = "deny"

src/dav.rs

@@ -23,6 +23,9 @@ fn segment(value: &str) -> String {
 
 /// Joins a connection-relative path onto the configured root.
 pub fn url(root: &str, path: &str) -> String {
+  if path == "/" || path.is_empty() {
+    return root.to_owned();
+  }
   let mut url = root.trim_end_matches('/').to_owned();
   for part in path.split('/').filter(|part| !part.is_empty()) {
     url.push('/');
@@ -238,23 +241,62 @@ pub fn name_of(href: &str) -> String {
   String::from_utf8_lossy(&decoded).into_owned()
 }
 
-/// The direct children in a Depth 1 reply. The first response describes the
-/// resource asked about, so it must be a collection before the rest can be
-/// called its children.
-pub fn children(found: &[Found]) -> Result<&[Found], ErrorCode> {
-  match found.split_first() {
-    None => Err(ErrorCode::NotFound),
-    Some((first, rest)) if first.collection => Ok(rest),
-    Some(_) => Err(ErrorCode::InvalidInput),
+/// An href can be an absolute URL or an absolute path (RFC 4918, section 8.3).
+fn href_path(href: &str) -> &str {
+  let path = match href.split_once("://") {
+    Some((_, authority_and_path)) => authority_and_path
+      .find('/')
+      .map(|start| &authority_and_path[start..])
+      .unwrap_or("/"),
+    None => href,
+  };
+  path
+    .split(['?', '#'])
+    .next()
+    .unwrap_or(path)
+    .trim_end_matches('/')
+}
+
+/// Responses may arrive in any order. Match the requested resource by its
+/// path, allowing collection slashes and equivalent percent encodings.
+pub fn resource<'a>(
+  found: &'a [Found],
+  url: &str,
+) -> Result<&'a Found, ErrorCode> {
+  found
+    .iter()
+    .find(|entry| {
+      href_path(&entry.href)
+        .split('/')
+        .map(name_of)
+        .eq(href_path(url).split('/').map(name_of))
+    })
+    .ok_or(ErrorCode::NotFound)
+}
+
+/// The direct children in a Depth 1 reply, excluding the requested directory.
+pub fn children<'a>(
+  found: &'a [Found],
+  url: &str,
+) -> Result<Vec<&'a Found>, ErrorCode> {
+  let parent = resource(found, url)?;
+  if !parent.collection {
+    return Err(ErrorCode::InvalidInput);
   }
+  Ok(
+    found
+      .iter()
+      .filter(|entry| !std::ptr::eq(*entry, parent))
+      .collect(),
+  )
 }
 
 /// Whether a Depth 1 reply describes something `remove` may delete: a file,
 /// or a collection with no children. DELETE on a collection is recursive in
 /// WebDAV, so this check is the only thing keeping a whole tree.
-pub fn removable(found: &[Found]) -> Result<(), ErrorCode> {
-  match children(found) {
-    Ok([]) => Ok(()),
+pub fn removable(found: &[Found], url: &str) -> Result<(), ErrorCode> {
+  match children(found, url) {
+    Ok(children) if children.is_empty() => Ok(()),
     Ok(_) => Err(ErrorCode::Conflict),
     Err(ErrorCode::InvalidInput) => Ok(()),
     Err(error) => Err(error),
@@ -265,24 +307,24 @@ pub fn removable(found: &[Found]) -> Result<(), ErrorCode> {
 mod tests {
   use super::{
     Body, Found, basic, children, multistatus, name_of, outcome, range_outcome,
-    removable, url,
+    removable, resource, url,
   };
   use crate::sdk::ErrorCode;
 
-  fn found(collection: bool) -> Found {
+  fn found(href: &str, collection: bool) -> Found {
     Found {
-      href: String::new(),
+      href: href.to_owned(),
       collection,
       length: 0,
       etag: None,
     }
   }
 
-  #[test]
-  fn paths_join_onto_the_root_without_growing_a_boundary() {
+  #[tokio::test]
+  async fn paths_join_onto_the_root_without_growing_a_boundary() {
     assert_eq!(
       url("https://dav.example/files/", "/"),
-      "https://dav.example/files"
+      "https://dav.example/files/"
     );
     assert_eq!(
       url("https://dav.example/files", "/notes/today.md"),
@@ -299,6 +341,46 @@ mod tests {
     );
   }
 
+  #[tokio::test]
+  async fn listings_keep_children_when_the_directory_is_not_first()
+  -> Result<(), ErrorCode> {
+    let entries = [found("/files/a.md", false), found("/files/", true)];
+    let listed = children(&entries, "https://dav.example/files/")?;
+    assert_eq!(listed.len(), 1);
+    assert_eq!(listed[0].href, "/files/a.md");
+    Ok(())
+  }
+
+  #[tokio::test]
+  async fn a_file_before_its_directory_never_allows_recursive_delete() {
+    let entries = [found("/files/a.md", false), found("/files/", true)];
+    assert_eq!(
+      removable(&entries, "https://dav.example/files/"),
+      Err(ErrorCode::Conflict)
+    );
+  }
+
+  #[tokio::test]
+  async fn hrefs_match_absolute_urls_and_equivalent_encoded_paths()
+  -> Result<(), ErrorCode> {
+    let entries = [
+      found("https://dav.example/my%20files/%e9%9b%aa.md", false),
+      found("https://dav.example/my%20files/", true),
+    ];
+    let listed = children(&entries, "https://dav.example/my%20files")?;
+    assert_eq!(listed.len(), 1);
+    assert_eq!(name_of(&listed[0].href), "雪.md");
+    assert!(
+      !resource(&entries, "https://dav.example/my%20files/%E9%9B%AA.md")?
+        .collection
+    );
+    assert_eq!(
+      removable(&entries, "https://dav.example/unrelated/"),
+      Err(ErrorCode::NotFound)
+    );
+    Ok(())
+  }
+
   #[test]
   fn credentials_encode_the_way_basic_auth_expects() {
     assert_eq!(basic("user", "pass"), "Basic dXNlcjpwYXNz");
@@ -366,21 +448,30 @@ mod tests {
     Ok(())
   }
 
-  #[test]
-  fn only_an_empty_directory_or_a_file_may_be_removed() {
-    assert_eq!(removable(&[found(false)]), Ok(()));
-    assert_eq!(removable(&[found(true)]), Ok(()));
+  #[tokio::test]
+  async fn only_an_empty_directory_or_a_file_may_be_removed() {
+    let url = "https://dav.example/files/";
+    assert_eq!(removable(&[found("/files/", false)], url), Ok(()));
+    assert_eq!(removable(&[found("/files/", true)], url), Ok(()));
     assert_eq!(
-      removable(&[found(true), found(false)]),
+      removable(&[found("/files/", true), found("/files/a.md", false)], url),
       Err(ErrorCode::Conflict)
     );
-    assert_eq!(removable(&[]), Err(ErrorCode::NotFound));
+    assert_eq!(removable(&[], url), Err(ErrorCode::NotFound));
     assert_eq!(
-      children(&[found(false)]).err(),
+      children(&[found("/files/", false)], url).err(),
       Some(ErrorCode::InvalidInput)
     );
     assert_eq!(
-      children(&[found(true), found(false), found(true)]).map(<[Found]>::len),
+      children(
+        &[
+          found("/files/", true),
+          found("/files/a.md", false),
+          found("/files/notes/", true)
+        ],
+        url,
+      )
+      .map(|children| children.len()),
       Ok(2)
     );
   }

src/lib.rs

@@ -34,10 +34,11 @@ struct Webdav;
 
 fn text(setting: Option<Setting>) -> Option<String> {
   match setting {
-    Some(Setting::Text(value)) | Some(Setting::Secret(value)) => {
+    Some(Setting::Text(value)) => {
       let value = value.trim().to_owned();
       (!value.is_empty()).then_some(value)
     }
+    Some(Setting::Secret(value)) => Some(value),
     Some(Setting::Toggle(_)) | None => None,
   }
 }
@@ -225,6 +226,7 @@ impl Guest for Webdav {
     _provider_id: String,
     config: Vec<(String, Setting)>,
   ) -> Result<Capabilities, ErrorCode> {
+    SESSION.set(None);
     let lookup = |wanted: &str| {
       config
         .iter()
@@ -245,6 +247,17 @@ impl Guest for Webdav {
       root,
       authorization,
     }));
+    let probe = Self::stat(Locator::Path("/".to_owned())).and_then(|info| {
+      if matches!(info.kind, EntryKind::Directory) {
+        Ok(())
+      } else {
+        Err(ErrorCode::InvalidInput)
+      }
+    });
+    if let Err(error) = probe {
+      SESSION.set(None);
+      return Err(error);
+    }
     Ok(Capabilities {
       write: true,
       mkdir: true,
@@ -281,7 +294,8 @@ impl Guest for Webdav {
       None => 0,
     };
     let found = describe(&path, "1")?;
-    let children: Vec<_> = dav::children(&found)?
+    let url = session(|session| Ok(dav::url(&session.root, &path)))?;
+    let children: Vec<_> = dav::children(&found, &url)?
       .iter()
       .map(|entry| Entry {
         name: dav::name_of(&entry.href),
@@ -400,7 +414,8 @@ impl Guest for Webdav {
   /// first and refused unless it is empty.
   fn remove(target: Locator) -> Result<(), ErrorCode> {
     let path = route(&target);
-    dav::removable(&describe(&path, "1")?)?;
+    let url = session(|session| Ok(dav::url(&session.root, &path)))?;
+    dav::removable(&describe(&path, "1")?, &url)?;
     exchange(host::Method::Delete, &path, Vec::new(), &[])?;
     Ok(())
   }
@@ -411,3 +426,36 @@ impl Guest for Webdav {
 }
 
 sdk::export!(Webdav with_types_in sdk);
+
+#[cfg(test)]
+mod tests {
+  use super::{SESSION, Session, Webdav, text};
+  use crate::sdk::{ErrorCode, Guest, Setting};
+
+  #[tokio::test]
+  async fn passwords_keep_leading_and_trailing_whitespace() {
+    assert_eq!(
+      text(Some(Setting::Secret(" pass word \t".to_owned()))),
+      Some(" pass word \t".to_owned())
+    );
+  }
+
+  #[tokio::test]
+  async fn an_empty_password_still_supplies_basic_auth_credentials() {
+    assert_eq!(
+      text(Some(Setting::Secret(String::new()))),
+      Some(String::new())
+    );
+  }
+
+  #[tokio::test]
+  async fn a_failed_reopen_discards_the_previous_connection() {
+    SESSION.set(Some(Session {
+      root: "https://dav.example/files/".to_owned(),
+      authorization: None,
+    }));
+    let result = Webdav::open("webdav".to_owned(), Vec::new());
+    assert_eq!(result.err(), Some(ErrorCode::InvalidInput));
+    assert!(SESSION.with_borrow(Option::is_none));
+  }
+}