Add login restriction

https://github.com/iv-org/invidious/issues/446#issuecomment-1342296218

src/invidious/config.cr

@@ -84,6 +84,7 @@ class Config
 
   # Used to tell Invidious it is behind a proxy, so links to resources should be https://
   property https_only : Bool?
+  property login_only : Bool?
   # HMAC signing key for CSRF tokens and verifying pubsub subscriptions
   property hmac_key : String = ""
   # Domain to be used for links to resources on the site where an absolute URL is required

src/invidious/routes/before_all.cr

@@ -122,5 +122,11 @@ module Invidious::Routes::BeforeAll
     end
 
     env.set "current_page", URI.encode_www_form(current_page)
+
+    unregistered_path_whitelist = {"/", "/login", "/licenses", "/privacy"}
+    if !env.get?("user") && !unregistered_path_whitelist.includes?(env.request.path) && CONFIG.login_only
+      env.response.headers["Location"] = "/login"
+      haltf env, status_code: 302
+    end
   end
 end