Support the blacklisted ip error and handle it

In the Go middleware

changelogs/unreleased/220561-fix-invalid-project-path-response-in-go-middleware.yml

+---
+title: Handle the blacklisted ip error in the Go middleware
+merge_request: 44614
+author:
+type: changed

lib/gitlab/middleware/go.rb

@@ -18,6 +18,15 @@ module Gitlab
         request = ActionDispatch::Request.new(env)
 
         render_go_doc(request) || @app.call(env)
+      rescue Gitlab::Auth::IpBlacklisted
+        Gitlab::AuthLogger.error(
+          message: 'Rack_Attack',
+          env: :blocklist,
+          remote_ip: request.ip,
+          request_method: request.request_method,
+          path: request.fullpath
+        )
+        Rack::Response.new('', 403).finish
       end
 
       private

spec/lib/gitlab/middleware/go_spec.rb

@@ -135,6 +135,17 @@ RSpec.describe Gitlab::Middleware::Go do
 
                       it_behaves_like 'unauthorized'
                     end
+
+                    context 'with a blacklisted ip' do
+                      it 'returns forbidden' do
+                        expect(Gitlab::Auth).to receive(:find_for_git_client).and_raise(Gitlab::Auth::IpBlacklisted)
+                        response = go
+
+                        expect(response[0]).to eq(403)
+                        expect(response[1]['Content-Length']).to eq('0')
+                        expect(response[2].body).to eq([''])
+                      end
+                    end
                   end
                 end
               end