From 02ab897f4fc0c72bd7af40f5139b5f122953701a Mon Sep 17 00:00:00 2001
From: Samuel Tardieu <sam@rfc1149.net>
Date: Tue, 18 Jul 2023 22:17:21 +0200
Subject: [PATCH] Fix webfinger fetching non-compliance (#69)

Allow webfinger to use "jrd+json" instead of "activity+json".
Fix #68.
---
 src/fetch/mod.rs       | 14 +++++++++++++-
 src/fetch/webfinger.rs |  9 +++++++--
 2 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/src/fetch/mod.rs b/src/fetch/mod.rs
index 7a9734c..28b709e 100644
--- a/src/fetch/mod.rs
+++ b/src/fetch/mod.rs
@@ -33,9 +33,21 @@ pub mod webfinger;
 /// If the value exceeds [FederationSettings.http_fetch_limit], the request is aborted with
 /// [Error::RequestLimit]. This prevents denial of service attacks where an attack triggers
 /// infinite, recursive fetching of data.
+///
+/// The `Accept` header will be set to the content of [`FEDERATION_CONTENT_TYPE`].
 pub async fn fetch_object_http<T: Clone, Kind: DeserializeOwned>(
     url: &Url,
     data: &Data<T>,
+) -> Result<Kind, Error> {
+    fetch_object_http_with_accept(url, data, FEDERATION_CONTENT_TYPE).await
+}
+
+/// Fetch a remote object over HTTP and convert to `Kind`. This function works exactly as
+/// [`fetch_object_http`] except that the `Accept` header is specified in `content_type`.
+async fn fetch_object_http_with_accept<T: Clone, Kind: DeserializeOwned>(
+    url: &Url,
+    data: &Data<T>,
+    content_type: &str,
 ) -> Result<Kind, Error> {
     let config = &data.config;
     // dont fetch local objects this way
@@ -51,7 +63,7 @@ pub async fn fetch_object_http<T: Clone, Kind: DeserializeOwned>(
     let req = config
         .client
         .get(url.as_str())
-        .header("Accept", FEDERATION_CONTENT_TYPE)
+        .header("Accept", content_type)
         .timeout(config.request_timeout);
 
     let res = if let Some((actor_id, private_key_pem)) = config.signed_fetch_actor.as_deref() {
diff --git a/src/fetch/webfinger.rs b/src/fetch/webfinger.rs
index 1ccf274..5a8a7ce 100644
--- a/src/fetch/webfinger.rs
+++ b/src/fetch/webfinger.rs
@@ -1,7 +1,7 @@
 use crate::{
     config::Data,
     error::{Error, Error::WebfingerResolveFailed},
-    fetch::{fetch_object_http, object_id::ObjectId},
+    fetch::{fetch_object_http_with_accept, object_id::ObjectId},
     traits::{Actor, Object},
     FEDERATION_CONTENT_TYPE,
 };
@@ -36,7 +36,9 @@ where
         format!("{protocol}://{domain}/.well-known/webfinger?resource=acct:{identifier}");
     debug!("Fetching webfinger url: {}", &fetch_url);
 
-    let res: Webfinger = fetch_object_http(&Url::parse(&fetch_url)?, data).await?;
+    let res: Webfinger =
+        fetch_object_http_with_accept(&Url::parse(&fetch_url)?, data, "application/jrd+json")
+            .await?;
 
     debug_assert_eq!(res.subject, format!("acct:{identifier}"));
     let links: Vec<Url> = res
@@ -231,5 +233,8 @@ mod tests {
             webfinger_resolve_actor::<DbConnection, DbUser>("LemmyDev@mastodon.social", &data)
                 .await;
         assert!(res.is_ok());
+        // poa.st is as of 2023-07-14 the largest Pleroma instance
+        let res = webfinger_resolve_actor::<DbConnection, DbUser>("graf@poa.st", &data).await;
+        assert!(res.is_ok());
     }
 }