From aab31eac670015a9e1d8ab81a24fa9d7ec255895 Mon Sep 17 00:00:00 2001
From: alemi <me@alemi.dev>
Date: Fri, 22 Mar 2024 00:17:52 +0100
Subject: [PATCH] feat: handle host-meta and webfingers

---
 Cargo.toml                    |  1 +
 src/activitypub/mod.rs        |  2 ++
 src/activitypub/well_known.rs | 58 +++++++++++++++++++++++++++++++++++
 src/server.rs                 |  3 ++
 4 files changed, 64 insertions(+)
 create mode 100644 src/activitypub/well_known.rs

diff --git a/Cargo.toml b/Cargo.toml
index 55682f8d..4803fb80 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -20,3 +20,4 @@ tokio = { version = "1.35.1", features = ["full"] }
 tracing = "0.1.40"
 tracing-subscriber = "0.3.18"
 uuid = { version = "1.8.0", features = ["v4"] }
+jrd = "0.1"
diff --git a/src/activitypub/mod.rs b/src/activitypub/mod.rs
index 195ec0e6..82251526 100644
--- a/src/activitypub/mod.rs
+++ b/src/activitypub/mod.rs
@@ -1,6 +1,8 @@
 pub mod user;
 pub mod object;
 pub mod activity;
+pub mod well_known;
+
 pub mod jsonld;
 pub use jsonld::JsonLD;
 
diff --git a/src/activitypub/well_known.rs b/src/activitypub/well_known.rs
new file mode 100644
index 00000000..5c8f52de
--- /dev/null
+++ b/src/activitypub/well_known.rs
@@ -0,0 +1,58 @@
+use axum::{extract::{Query, State}, http::StatusCode, response::{IntoResponse, Response}};
+use jrd::{JsonResourceDescriptor, JsonResourceDescriptorLink};
+use sea_orm::EntityTrait;
+
+use crate::{server::Context, model};
+
+#[derive(Debug, serde::Deserialize)]
+pub struct WebfingerQuery {
+	pub resource: String,
+}
+
+pub struct JsonRD<T>(pub T);
+impl<T: serde::Serialize> IntoResponse for JsonRD<T> {
+	fn into_response(self) -> Response {
+		([("Content-Type", "application/jrd+json")], axum::Json(self.0)).into_response()
+	}
+}
+
+pub async fn webfinger(State(ctx): State<Context>, Query(query): Query<WebfingerQuery>) -> Result<JsonRD<JsonResourceDescriptor>, StatusCode> {
+	if let Some((user, domain)) = query.resource.split_once('@') {
+		let uid = ctx.uid(user.to_string());
+		match model::user::Entity::find_by_id(uid)
+			.one(ctx.db())
+			.await
+		{
+			Ok(Some(x)) => Ok(JsonRD(JsonResourceDescriptor {
+				subject: format!("acct:{user}@{domain}"),
+				aliases: vec![x.id.clone()],
+				links: vec![
+					JsonResourceDescriptorLink {
+						rel: "self".to_string(),
+						link_type: Some("application/ld+json".to_string()),
+						href: Some(x.id),
+						properties: jrd::Map::default(),
+						titles: jrd::Map::default(),
+					},
+				],
+				expires: None,
+				properties: jrd::Map::default(),
+			})),
+			Ok(None) => Err(StatusCode::NOT_FOUND),
+			Err(e) => {
+				tracing::error!("error executing webfinger query: {e}");
+				Err(StatusCode::INTERNAL_SERVER_ERROR)
+			},
+		}
+	} else {
+		Err(StatusCode::UNPROCESSABLE_ENTITY)
+	}
+}
+
+// i don't even want to bother with XML, im just returning a formatted xml string
+pub async fn host_meta(State(ctx): State<Context>) -> String {
+	format!(r#"<?xml version="1.0" encoding="UTF-8"?>
+	<XRD xmlns="http://docs.oasis-open.org/ns/xri/xrd-1.0">
+		<Link type="application/xrd+xml" template="{}/.well-known/webfinger?resource={{uri}}" rel="lrdd" />
+	</XRD>"#, ctx.base())
+}
diff --git a/src/server.rs b/src/server.rs
index 860b410f..040313e6 100644
--- a/src/server.rs
+++ b/src/server.rs
@@ -77,6 +77,9 @@ pub async fn serve(db: DatabaseConnection, domain: String) {
 		.route("/", get(ap::view))
 		.route("/inbox", post(ap::inbox))
 		.route("/outbox", get(ap::outbox))
+		// .well-known and discovery
+		.route("/.well-known/webfinger", get(ap::well_known::webfinger))
+		.route("/.well-known/host-meta", get(ap::well_known::host_meta))
 		// actor routes
 		.route("/users/:id", get(ap::user::view))
 		.route("/users/:id/inbox", post(ap::user::inbox))