add harmless check for presence PUT matching sender user

this is already done but we just don't error and always
use the sender user. match synapse behaviour where we check
and error.

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

src/api/client/presence.rs

@@ -16,6 +16,14 @@ pub(crate) async fn set_presence_route(body: Ruma<set_presence::v3::Request>) ->
 	}
 
 	let sender_user = body.sender_user.as_ref().expect("user is authenticated");
+
+	if sender_user != &body.user_id && body.appservice_info.is_none() {
+		return Err(Error::BadRequest(
+			ErrorKind::InvalidParam,
+			"Not allowed to set presence of other users",
+		));
+	}
+
 	services()
 		.presence
 		.set_presence(sender_user, &body.presence, None, None, body.status_msg.clone())?;