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https://github.com/LemmyNet/activitypub-federation-rust.git
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102 lines
3.3 KiB
Rust
102 lines
3.3 KiB
Rust
//! Utilities for fetching data from other servers
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//!
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#![doc = include_str!("../../docs/07_fetching_data.md")]
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use crate::{
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config::Data,
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error::Error,
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http_signatures::sign_request,
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reqwest_shim::ResponseExt,
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FEDERATION_CONTENT_TYPE,
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};
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use bytes::Bytes;
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use http::StatusCode;
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use serde::de::DeserializeOwned;
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use std::sync::atomic::Ordering;
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use tracing::info;
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use url::Url;
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/// Typed wrapper for collection IDs
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pub mod collection_id;
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/// Typed wrapper for Activitypub Object ID which helps with dereferencing and caching
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pub mod object_id;
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/// Resolves identifiers of the form `name@example.com`
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pub mod webfinger;
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/// Response from fetching a remote object
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pub struct FetchObjectResponse<Kind> {
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/// The resolved object
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pub object: Kind,
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/// Contains the final URL (different from request URL in case of redirect)
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pub url: Url,
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}
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/// Fetch a remote object over HTTP and convert to `Kind`.
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///
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/// [crate::fetch::object_id::ObjectId::dereference] wraps this function to add caching and
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/// conversion to database type. Only use this function directly in exceptional cases where that
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/// behaviour is undesired.
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///
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/// Every time an object is fetched via HTTP, [RequestData.request_counter] is incremented by one.
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/// If the value exceeds [FederationSettings.http_fetch_limit], the request is aborted with
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/// [Error::RequestLimit]. This prevents denial of service attacks where an attack triggers
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/// infinite, recursive fetching of data.
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///
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/// The `Accept` header will be set to the content of [`FEDERATION_CONTENT_TYPE`].
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pub async fn fetch_object_http<T: Clone, Kind: DeserializeOwned>(
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url: &Url,
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data: &Data<T>,
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) -> Result<FetchObjectResponse<Kind>, Error> {
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fetch_object_http_with_accept(url, data, FEDERATION_CONTENT_TYPE).await
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}
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/// Fetch a remote object over HTTP and convert to `Kind`. This function works exactly as
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/// [`fetch_object_http`] except that the `Accept` header is specified in `content_type`.
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async fn fetch_object_http_with_accept<T: Clone, Kind: DeserializeOwned>(
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url: &Url,
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data: &Data<T>,
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content_type: &str,
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) -> Result<FetchObjectResponse<Kind>, Error> {
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let config = &data.config;
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// dont fetch local objects this way
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debug_assert!(url.domain() != Some(&config.domain));
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config.verify_url_valid(url).await?;
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info!("Fetching remote object {}", url.to_string());
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let counter = data.request_counter.fetch_add(1, Ordering::SeqCst);
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if counter > config.http_fetch_limit {
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return Err(Error::RequestLimit);
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}
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let req = config
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.client
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.get(url.as_str())
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.header("Accept", content_type)
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.timeout(config.request_timeout);
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let res = if let Some((actor_id, private_key_pem)) = config.signed_fetch_actor.as_deref() {
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let req = sign_request(
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req,
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actor_id,
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Bytes::new(),
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private_key_pem.clone(),
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data.config.http_signature_compat,
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)
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.await?;
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config.client.execute(req).await
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} else {
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req.send().await
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}
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.map_err(|e| Error::FetchError(url.clone(), e))?;
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if res.status() == StatusCode::GONE {
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return Err(Error::ObjectDeleted(url.clone()));
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}
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let url = res.url().clone();
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Ok(FetchObjectResponse {
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object: res.json_limited().await?,
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url,
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})
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}
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