Only inject gon variables and perform redirects for HTML

Instead of excluding XHRs for these actions, we only want to perform
them when we're serving an HTML page. If we're serving an image or an
Atom feed, they are mostly useless:

1. Gon variables can't be used by an image.
2. Redirects won't be seen if an image is embedded in another page.

app/controllers/application_controller.rb

@@ -20,11 +20,11 @@ class ApplicationController < ActionController::Base
   before_action :authenticate_user!, except: [:route_not_found]
   before_action :enforce_terms!, if: :should_enforce_terms?
   before_action :validate_user_service_ticket!
-  before_action :check_password_expiration
+  before_action :check_password_expiration, if: :html_request?
   before_action :ldap_security_check
   before_action :sentry_context
   before_action :default_headers
-  before_action :add_gon_variables, unless: [:peek_request?, :json_request?]
+  before_action :add_gon_variables, if: :html_request?
   before_action :configure_permitted_parameters, if: :devise_controller?
   before_action :require_email, unless: :devise_controller?
   before_action :active_user_check, unless: :devise_controller?
@@ -451,8 +451,8 @@ class ApplicationController < ActionController::Base
     response.headers['Page-Title'] = URI.escape(page_title('GitLab'))
   end
 
-  def peek_request?
-    request.path.start_with?('/-/peek')
+  def html_request?
+    request.format.html?
   end
 
   def json_request?
@@ -462,7 +462,7 @@ class ApplicationController < ActionController::Base
   def should_enforce_terms?
     return false unless Gitlab::CurrentSettings.current_application_settings.enforce_terms
 
-    !(peek_request? || devise_controller?)
+    html_request? && !devise_controller?
   end
 
   def set_usage_stats_consent_flag

app/controllers/concerns/confirm_email_warning.rb

@@ -4,15 +4,18 @@ module ConfirmEmailWarning
   extend ActiveSupport::Concern
 
   included do
-    before_action :set_confirm_warning, if: -> { Feature.enabled?(:soft_email_confirmation) }
+    before_action :set_confirm_warning, if: :show_confirm_warning?
   end
 
   protected
 
+  def show_confirm_warning?
+    html_request? && request.get? && Feature.enabled?(:soft_email_confirmation)
+  end
+
   def set_confirm_warning
     return unless current_user
     return if current_user.confirmed?
-    return if peek_request? || json_request? || !request.get?
 
     email = current_user.unconfirmed_email || current_user.email
 

app/controllers/concerns/uploads_actions.rb

 # frozen_string_literal: true
 
 module UploadsActions
+  extend ActiveSupport::Concern
   include Gitlab::Utils::StrongMemoize
   include SendFileUpload
 
   UPLOAD_MOUNTS = %w(avatar attachment file logo header_logo favicon).freeze
 
+  included do
+    prepend_before_action :set_request_format_from_path_extension
+  end
+
   def create
     uploader = UploadService.new(model, params[:file], uploader_class).execute
 
@@ -64,6 +69,18 @@ module UploadsActions
 
   private
 
+  # From ActionDispatch::Http::MimeNegotiation. We have an initializer that
+  # monkey-patches this method out (so that repository paths don't guess a
+  # format based on extension), but we do want this behaviour when serving
+  # uploads.
+  def set_request_format_from_path_extension
+    path = request.headers['action_dispatch.original_path'] || request.headers['PATH_INFO']
+
+    if match = path&.match(/\.(\w+)\z/)
+      request.format = match.captures.first
+    end
+  end
+
   def uploader_class
     raise NotImplementedError
   end

spec/controllers/application_controller_spec.rb

@@ -90,14 +90,6 @@ describe ApplicationController do
       let(:format) { :html }
 
       it_behaves_like 'setting gon variables'
-
-      context 'for peek requests' do
-        before do
-          request.path = '/-/peek'
-        end
-
-        it_behaves_like 'not setting gon variables'
-      end
     end
 
     context 'with json format' do
@@ -105,6 +97,12 @@ describe ApplicationController do
 
       it_behaves_like 'not setting gon variables'
     end
+
+    context 'with atom format' do
+      let(:format) { :atom }
+
+      it_behaves_like 'not setting gon variables'
+    end
   end
 
   describe 'session expiration' do

spec/controllers/uploads_controller_spec.rb

@@ -228,10 +228,10 @@ describe UploadsController do
             user.block
           end
 
-          it "redirects to the sign in page" do
+          it "responds with status 401" do
             get :show, params: { model: "user", mounted_as: "avatar", id: user.id, filename: "dk.png" }
 
-            expect(response).to redirect_to(new_user_session_path)
+            expect(response).to have_gitlab_http_status(401)
           end
         end
 
@@ -320,10 +320,10 @@ describe UploadsController do
         end
 
         context "when not signed in" do
-          it "redirects to the sign in page" do
+          it "responds with status 401" do
             get :show, params: { model: "project", mounted_as: "avatar", id: project.id, filename: "dk.png" }
 
-            expect(response).to redirect_to(new_user_session_path)
+            expect(response).to have_gitlab_http_status(401)
           end
         end
 
@@ -343,10 +343,10 @@ describe UploadsController do
                 project.add_maintainer(user)
               end
 
-              it "redirects to the sign in page" do
+              it "responds with status 401" do
                 get :show, params: { model: "project", mounted_as: "avatar", id: project.id, filename: "dk.png" }
 
-                expect(response).to redirect_to(new_user_session_path)
+                expect(response).to have_gitlab_http_status(401)
               end
             end
 
@@ -439,10 +439,10 @@ describe UploadsController do
                 user.block
               end
 
-              it "redirects to the sign in page" do
+              it "responds with status 401" do
                 get :show, params: { model: "group", mounted_as: "avatar", id: group.id, filename: "dk.png" }
 
-                expect(response).to redirect_to(new_user_session_path)
+                expect(response).to have_gitlab_http_status(401)
               end
             end
 
@@ -526,10 +526,10 @@ describe UploadsController do
         end
 
         context "when not signed in" do
-          it "redirects to the sign in page" do
+          it "responds with status 401" do
             get :show, params: { model: "note", mounted_as: "attachment", id: note.id, filename: "dk.png" }
 
-            expect(response).to redirect_to(new_user_session_path)
+            expect(response).to have_gitlab_http_status(401)
           end
         end
 
@@ -549,10 +549,10 @@ describe UploadsController do
                 project.add_maintainer(user)
               end
 
-              it "redirects to the sign in page" do
+              it "responds with status 401" do
                 get :show, params: { model: "note", mounted_as: "attachment", id: note.id, filename: "dk.png" }
 
-                expect(response).to redirect_to(new_user_session_path)
+                expect(response).to have_gitlab_http_status(401)
               end
             end
 

spec/requests/user_avatar_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe 'Loading a user avatar' do
+  let(:user) { create(:user, :with_avatar) }
+
+  context 'when logged in' do
+    # The exact query count will vary depending on the 2FA settings of the
+    # instance, group, and user. Removing those extra 2FA queries in this case
+    # may not be a good idea, so we just set up the ideal case.
+    before do
+      stub_application_setting(require_two_factor_authentication: true)
+
+      login_as(create(:user, :two_factor))
+    end
+
+    # One each for: current user, avatar user, and upload record
+    it 'only performs three SQL queries' do
+      get user.avatar_url # Skip queries on first application load
+
+      expect(response).to have_gitlab_http_status(200)
+      expect { get user.avatar_url }.not_to exceed_query_limit(3)
+    end
+  end
+
+  context 'when logged out' do
+    # One each for avatar user and upload record
+    it 'only performs two SQL queries' do
+      get user.avatar_url # Skip queries on first application load
+
+      expect(response).to have_gitlab_http_status(200)
+      expect { get user.avatar_url }.not_to exceed_query_limit(2)
+    end
+  end
+end