vstorage/webcal.rs
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// Copyright 2023-2024 Hugo Osvaldo Barrera
//
// SPDX-License-Identifier: EUPL-1.2
//! Implements reading entries from a remote webcal resource.
//!
//! Webcal is a de-facto standard, and is basically a single icalendar file hosted via http(s).
//!
//! See the [Webcal wikipedia page](https://en.wikipedia.org/wiki/Webcal).
use async_trait::async_trait;
use http::{Method, Request, Response, StatusCode, Uri};
use http_body_util::BodyExt;
use hyper::body::Incoming;
use tower::Service;
use crate::{
base::{
CalendarProperty, Collection, FetchedItem, IcsItem, Item, ItemRef, ListedProperty, Storage,
},
disco::{DiscoveredCollection, Discovery},
simple_component::Component,
CollectionId, Error, ErrorKind, Etag, Href, Result,
};
/// A storage which exposes items in remote icalendar resource.
///
/// A webcal storage contains exactly one collection, which contains all the entires found in the
/// remote resource. The name of this single collection is specified via the `collection_id`
/// argument.
///
/// This storage is a bit of an odd one (since in reality, there's no concept of collections in
/// webcal). The extra abstraction layer is here merely to match the format of other storages.
///
/// # Href
///
/// The `href` for this meaningless. A string matching the `collection_id` property is used to
/// describe the only available collection.
// TODO: If an alternative href is provided, it should be used as a path on the same host.
// Note that discovery will only support the one matching the input URL.
pub struct WebCalStorage<C>
where
// XXX: Clone can be dropped after tower drops it `mut` for `tower_service::Service::call`
// See: https://github.com/hyperium/hyper/issues/3784#issuecomment-2491667302
// See: https://github.com/tower-rs/tower/issues/753
C: Service<Request<String>, Response = Response<Incoming>> + Send + Sync + Clone + 'static,
C::Error: std::error::Error + Send + Sync,
C::Future: Send + Sync,
{
/// The URL of the remote icalendar resource. Must be HTTP or HTTPS.
url: Uri,
/// The href and id to be given to the single collection available.
collection_id: CollectionId,
http_client: C,
}
impl<C> WebCalStorage<C>
where
C: Service<Request<String>, Response = Response<Incoming>> + Send + Sync + Clone + 'static,
C::Error: std::error::Error + Send + Sync,
C::Future: Send + Sync,
{
/// Build a new `Storage` instance.
///
/// # Errors
///
/// If there are errors discovering the CardDAV server.
// TODO: take custom client as input.
pub fn new(http_client: C, url: Uri, collection_id: CollectionId) -> Result<WebCalStorage<C>> {
Ok(WebCalStorage {
url,
collection_id,
http_client,
})
}
/// Helper method to fetch a URL and return its body as a String.
///
/// Be warned! This swallows headers (including `Etag`!).
async fn fetch_raw(&self, url: &Uri) -> Result<String> {
let req = Request::builder()
.method(Method::GET)
.uri(url)
.body(String::new())
.map_err(|e| Error::new(ErrorKind::InvalidInput, e))?;
let response = self
.http_client
.clone()
.call(req)
.await
.map_err(|e| Error::new(ErrorKind::Io, e))?;
match response.status() {
StatusCode::NOT_FOUND | StatusCode::GONE => {
return Err(Error::new(
ErrorKind::DoesNotExist,
"The remote resource does not exist.",
))
}
StatusCode::OK => {}
code => {
return Err(Error::new(
ErrorKind::Io,
format!("request returned {code}"),
))
}
}
let (_head, body) = response.into_parts();
let data = body
.collect()
.await
.map_err(|e| Error::new(ErrorKind::Io, e))?
.to_bytes();
// TODO: handle non-UTF-8 data (e.g.: Content-Type/charset).
// TODO: can I avoid making a copy of the entire response here?
String::from_utf8(data.to_vec()).map_err(|e| Error::new(ErrorKind::InvalidData, e))
}
}
#[async_trait]
impl<C> Storage<IcsItem> for WebCalStorage<C>
where
C: Service<Request<String>, Response = Response<Incoming>> + Send + Sync + Clone + 'static,
C::Error: std::error::Error + Send + Sync,
C::Future: Send + Sync,
{
/// Checks that the remove resource exists and whether it looks like an icalendar resource.
async fn check(&self) -> Result<()> {
// TODO: Should map status codes to io::Error. if 404 -> NotFound, etc.
let raw = self.fetch_raw(&self.url).await?;
if !raw.starts_with("BEGIN:VCALENDAR") {
return Err(Error::new(
ErrorKind::InvalidData,
"response for URL doesn't look like a calendar",
));
}
Ok(())
}
/// Returns a single collection with the name originally specified.
async fn discover_collections(&self) -> Result<Discovery> {
// TODO: shouldn't I check that the collection actually exists?
Ok(vec![DiscoveredCollection::new(
self.url.path().to_string(),
self.collection_id.clone(),
)]
.into())
}
/// Unsupported for this storage type.
async fn create_collection(&self, _: &str) -> Result<Collection> {
Err(Error::new(
ErrorKind::Unsupported,
"creating collections via webcal is not supported",
))
}
/// Unsupported for this storage type.
async fn destroy_collection(&self, _: &str) -> Result<()> {
Err(Error::new(
ErrorKind::Unsupported,
"destroying collections via webcal is not supported",
))
}
/// Enumerates items in this collection.
///
/// Note that, due to the nature of webcal, the whole collection needs to be retrieved. If some
/// items need to be read as well, it is generally best to use
/// [`WebCalStorage::get_all_items`] instead.
async fn list_items(&self, _collection: &str) -> Result<Vec<ItemRef>> {
let raw = self.fetch_raw(&self.url).await?;
// TODO: it would be best if the parser could operate on a stream, although that might
// complicate copying VTIMEZONEs inline if they are at the end of the stream.
let refs = Component::parse(&raw)
.map_err(|e| Error::new(ErrorKind::InvalidData, e))?
.into_split_collection()
.map_err(|e| Error::new(ErrorKind::InvalidData, e))?
.iter()
.map(|c| {
let item = IcsItem::from(c.to_string());
let hash = item.hash();
ItemRef {
href: item.ident(),
etag: hash.into(),
}
})
.collect();
Ok(refs)
}
/// Returns a single item from the collection.
///
/// Note that, due to the nature of webcal, the whole collection needs to be retrieved. It is
/// strongly recommended to use [`WebCalStorage::get_all_items`] instead.
async fn get_item(&self, href: &str) -> Result<(IcsItem, Etag)> {
let raw = self.fetch_raw(&self.url).await?;
// TODO: it would be best if the parser could operate on a stream, although that might
// complicate inlining VTIMEZONEs that are at the end.
let item = Component::parse(&raw)
.map_err(|e| Error::new(ErrorKind::InvalidData, e))?
.into_split_collection()
.map_err(|e| Error::new(ErrorKind::InvalidData, e))?
.iter()
.find_map(|c| {
let item = IcsItem::from(c.to_string());
if item.ident() == href {
Some(item)
} else {
None
}
})
.ok_or_else(|| Error::from(ErrorKind::DoesNotExist))?;
let hash = item.hash();
Ok((item, hash.into()))
}
/// Returns multiple items from the collection.
///
/// Note that, due to the nature of webcal, the whole collection needs to be retrieved. It is
/// generally best to use [`WebCalStorage::get_all_items`] instead.
async fn get_many_items(&self, hrefs: &[&str]) -> Result<Vec<FetchedItem<IcsItem>>> {
let raw = self.fetch_raw(&self.url).await?;
// TODO: it would be best if the parser could operate on a stream, although that might
// complicate inlining VTIMEZONEs that are at the end.
Component::parse(&raw)
.map_err(|e| Error::new(ErrorKind::InvalidData, e))?
.into_split_collection()
.map_err(|e| Error::new(ErrorKind::InvalidData, e))?
.iter()
.filter_map(|c| {
let item = IcsItem::from(c.to_string());
if hrefs.contains(&(item.ident().as_ref())) {
Some(Ok(FetchedItem {
href: item.ident(),
etag: item.hash().into(),
item,
}))
} else {
None
}
})
.collect()
}
/// Fetch all items in the collection.
///
/// Performs a single HTTP(s) request to fetch all items.
async fn get_all_items(&self, _collection: &str) -> Result<Vec<FetchedItem<IcsItem>>> {
let raw = self.fetch_raw(&self.url).await?;
// TODO: it would be best if the parser could operate on a stream, although that might
// complicate inlining VTIMEZONEs that are at the end.
let components = Component::parse(&raw)
.map_err(|e| Error::new(ErrorKind::InvalidData, e))?
.into_split_collection()
.map_err(|e| Error::new(ErrorKind::InvalidData, e))?;
components
.iter()
.map(|c| {
let item = IcsItem::from(c.to_string());
Ok(FetchedItem {
href: item.ident(),
etag: item.hash().into(),
item,
})
})
.collect()
}
/// Unsupported for this storage type.
async fn add_item(&self, _collection: &str, _: &IcsItem) -> Result<ItemRef> {
Err(Error::new(
ErrorKind::Unsupported,
"adding items via webcal is not supported",
))
}
/// Unsupported for this storage type.
async fn update_item(&self, _: &str, _: &Etag, _: &IcsItem) -> Result<Etag> {
Err(Error::new(
ErrorKind::Unsupported,
"updating items via webcal is not supported",
))
}
/// Unsupported for this storage type.
async fn set_property(&self, _: &str, _: CalendarProperty, _: &str) -> Result<()> {
Err(Error::new(
ErrorKind::Unsupported,
"setting metadata via webcal is not supported",
))
}
/// Unsupported for this storage type.
async fn unset_property(&self, _: &str, _: CalendarProperty) -> Result<()> {
Err(Error::new(
ErrorKind::Unsupported,
"unsetting metadata via webcal is not supported",
))
}
/// Unsupported for this storage type.
async fn get_property(&self, _: &str, _: CalendarProperty) -> Result<Option<String>> {
// TODO: return None?
Err(Error::new(
ErrorKind::Unsupported,
"getting metadata via webcal is not supported",
))
}
async fn delete_item(&self, _: &str, _: &Etag) -> Result<()> {
Err(Error::new(
ErrorKind::Unsupported,
"deleting items via webcal is not supported",
))
}
fn href_for_collection_id(&self, id: &CollectionId) -> Result<Href> {
if id == &self.collection_id {
Ok(self.url.path().to_string())
} else {
Err(Error::new(
ErrorKind::Unsupported,
"discovery of arbitrary collections is not supported",
))
}
}
async fn list_properties(&self, _: &str) -> Result<Vec<ListedProperty<CalendarProperty>>> {
Err(Error::new(
ErrorKind::Unsupported,
"webcal does not support properties",
))
}
}
#[cfg(test)]
mod test {
use http::Uri;
use hyper_rustls::HttpsConnectorBuilder;
use hyper_util::{client::legacy::Client, rt::TokioExecutor};
use crate::{base::Storage, webcal::WebCalStorage};
// FIXME: only run this test with a dedicated flag for networked test.
// FIXME: use a webcal link hosted by me.
// TODO: these are just validation tests and not suitable as a keeper.
#[tokio::test]
#[ignore = "uses internet resource"]
async fn test_dummy() {
let connector = HttpsConnectorBuilder::new()
.with_native_roots()
.unwrap()
.https_or_http()
.enable_http1()
.build();
let client = Client::builder(TokioExecutor::new()).build(connector);
let storage = WebCalStorage::new(
client,
Uri::try_from("https://www.officeholidays.com/ics/netherlands").unwrap(),
"holidays".parse().unwrap(),
)
.unwrap();
storage.check().await.unwrap();
let collection = "holidays";
let discovery = &storage.discover_collections().await.unwrap();
assert_eq!(
&collection,
&discovery.collections().first().unwrap().href()
);
let item_refs = storage.list_items(collection).await.unwrap();
for item_ref in &item_refs {
let (_item, etag) = storage.get_item(&item_ref.href).await.unwrap();
// Might file if upstream file mutates between requests.
assert_eq!(etag, item_ref.etag);
}
let hrefs: Vec<&str> = item_refs.iter().map(|r| r.href.as_ref()).collect();
let many = storage.get_many_items(&hrefs.clone()).await.unwrap();
assert_eq!(many.len(), hrefs.len());
assert_eq!(many.len(), item_refs.len());
// TODO: compare their contents and etags, though these should all match.
}
}