1 files changed, 135 insertions, 0 deletions
diff --git a/lib/api/go_proxy.rb b/lib/api/go_proxy.rb
new file mode 100755
index 00000000000..c0207f9169c
--- /dev/null
+++ b/lib/api/go_proxy.rb
@@ -0,0 +1,135 @@
+# frozen_string_literal: true
+module API
+  class GoProxy < Grape::API::Instance
+    helpers Gitlab::Golang
+    helpers ::API::Helpers::PackagesHelpers
+
+    # basic semver, except case encoded (A => !a)
+    MODULE_VERSION_REGEX = /v(0|[1-9]\d*)\.(0|[1-9]\d*)\.(0|[1-9]\d*)(?:-([-.!a-z0-9]+))?(?:\+([-.!a-z0-9]+))?/.freeze
+
+    MODULE_VERSION_REQUIREMENTS = { module_version: MODULE_VERSION_REGEX }.freeze
+
+    before { require_packages_enabled! }
+
+    helpers do
+      def case_decode(str)
+        # Converts "github.com/!azure" to "github.com/Azure"
+        #
+        # From `go help goproxy`:
+        #
+        # > To avoid problems when serving from case-sensitive file systems,
+        # > the <module> and <version> elements are case-encoded, replacing
+        # > every uppercase letter with an exclamation mark followed by the
+        # > corresponding lower-case letter: github.com/Azure encodes as
+        # > github.com/!azure.
+
+        str.gsub(/![[:alpha:]]/) { |s| s[1..].upcase }
+      end
+
+      def find_project!(id)
+        # based on API::Helpers::Packages::BasicAuthHelpers#authorized_project_find!
+
+        project = find_project(id)
+
+        return project if project && can?(current_user, :read_project, project)
+
+        if current_user
+          not_found!('Project')
+        else
+          unauthorized!
+        end
+      end
+
+      def find_module
+        not_found! unless Feature.enabled?(:go_proxy, user_project)
+
+        module_name = case_decode params[:module_name]
+        bad_request!('Module Name') if module_name.blank?
+
+        mod = ::Packages::Go::ModuleFinder.new(user_project, module_name).execute
+
+        not_found! unless mod
+
+        mod
+      end
+
+      def find_version
+        module_version = case_decode params[:module_version]
+        ver = ::Packages::Go::VersionFinder.new(find_module).find(module_version)
+
+        not_found! unless ver&.valid?
+
+        ver
+
+      rescue ArgumentError
+        not_found!
+      end
+    end
+
+    params do
+      requires :id, type: String, desc: 'The ID of a project'
+      requires :module_name, type: String, desc: 'Module name', coerce_with: ->(val) { CGI.unescape(val) }
+    end
+    route_setting :authentication, job_token_allowed: true, basic_auth_personal_access_token: true
+    resource :projects, requirements: API::NAMESPACE_OR_PROJECT_REQUIREMENTS do
+      before do
+        authorize_read_package!
+      end
+
+      namespace ':id/packages/go/*module_name/@v' do
+        desc 'Get all tagged versions for a given Go module' do
+          detail 'See `go help goproxy`, GET $GOPROXY/<module>/@v/list. This feature was introduced in GitLab 13.1.'
+        end
+        get 'list' do
+          mod = find_module
+
+          content_type 'text/plain'
+          mod.versions.map { |t| t.name }.join("\n")
+        end
+
+        desc 'Get information about the given module version' do
+          detail 'See `go help goproxy`, GET $GOPROXY/<module>/@v/<version>.info. This feature was introduced in GitLab 13.1.'
+          success ::API::Entities::GoModuleVersion
+        end
+        params do
+          requires :module_version, type: String, desc: 'Module version'
+        end
+        get ':module_version.info', requirements: MODULE_VERSION_REQUIREMENTS do
+          ver = find_version
+
+          present ::Packages::Go::ModuleVersionPresenter.new(ver), with: ::API::Entities::GoModuleVersion
+        end
+
+        desc 'Get the module file of the given module version' do
+          detail 'See `go help goproxy`, GET $GOPROXY/<module>/@v/<version>.mod. This feature was introduced in GitLab 13.1.'
+        end
+        params do
+          requires :module_version, type: String, desc: 'Module version'
+        end
+        get ':module_version.mod', requirements: MODULE_VERSION_REQUIREMENTS do
+          ver = find_version
+
+          content_type 'text/plain'
+          ver.gomod
+        end
+
+        desc 'Get a zip of the source of the given module version' do
+          detail 'See `go help goproxy`, GET $GOPROXY/<module>/@v/<version>.zip. This feature was introduced in GitLab 13.1.'
+        end
+        params do
+          requires :module_version, type: String, desc: 'Module version'
+        end
+        get ':module_version.zip', requirements: MODULE_VERSION_REQUIREMENTS do
+          ver = find_version
+
+          content_type 'application/zip'
+          env['api.format'] = :binary
+          header['Content-Disposition'] = ActionDispatch::Http::ContentDisposition.format(disposition: 'attachment', filename: ver.name + '.zip')
+          header['Content-Transfer-Encoding'] = 'binary'
+          status :ok
+          body ver.archive.string
+        end
+      end
+    end
+  end
+end