add appservice ping client endpoint (MSC2659)

Signed-off-by: strawberry <strawberry@puppygock.gay>

src/api/client/appservice.rs

@@ -0,0 +1,47 @@
+use axum::extract::State;
+use conduit::{err, Err, Result};
+use ruma::api::{appservice::ping, client::appservice::request_ping};
+
+use crate::Ruma;
+
+/// # `POST /_matrix/client/v1/appservice/{appserviceId}/ping`
+///
+/// Ask the homeserver to ping the application service to ensure the connection
+/// works.
+pub(crate) async fn appservice_ping(
+	State(services): State<crate::State>, body: Ruma<request_ping::v1::Request>,
+) -> Result<request_ping::v1::Response> {
+	let appservice_info = body
+		.appservice_info
+		.as_ref()
+		.ok_or_else(|| err!(Request(Forbidden("This endpoint can only be called by appservices."))))?;
+
+	if body.appservice_id != appservice_info.registration.id {
+		return Err!(Request(Forbidden(
+			"Appservices can only ping themselves (wrong appservice ID)."
+		)));
+	}
+
+	if appservice_info.registration.url.is_none() {
+		return Err!(Request(UrlNotSet(
+			"Appservice does not have a URL set, there is nothing to ping."
+		)));
+	}
+
+	let timer = tokio::time::Instant::now();
+
+	let _response = services
+		.sending
+		.send_appservice_request(
+			appservice_info.registration.clone(),
+			ping::send_ping::v1::Request {
+				transaction_id: body.transaction_id.clone(),
+			},
+		)
+		.await?
+		.expect("We already validated if an appservice URL exists above");
+
+	Ok(request_ping::v1::Response {
+		duration: timer.elapsed(),
+	})
+}

src/api/client/mod.rs

@@ -1,5 +1,6 @@
 pub(super) mod account;
 pub(super) mod alias;
+pub(super) mod appservice;
 pub(super) mod backup;
 pub(super) mod capabilities;
 pub(super) mod config;
@@ -38,6 +39,7 @@ pub(super) mod voip;
 
 pub(super) use account::*;
 pub(super) use alias::*;
+pub(super) use appservice::*;
 pub(super) use backup::*;
 pub(super) use capabilities::*;
 pub(super) use config::*;

src/api/router.rs

@@ -22,6 +22,7 @@ use crate::{client, server};
 pub fn build(router: Router<State>, server: &Server) -> Router<State> {
 	let config = &server.config;
 	let mut router = router
+        .ruma_route(client::appservice_ping)
 		.ruma_route(client::get_supported_versions_route)
 		.ruma_route(client::get_register_available_route)
 		.ruma_route(client::register_route)