DEV: Extract shared external upload routes into controller helper (#14984)

This commit refactors the direct external upload routes (get presigned
put, complete external, create/abort/complete multipart) into a
helper which is then included in both BackupController and the
UploadController. This is done so UploadController doesn't need
strange backup logic added to it, and so each controller implementing
this helper can do their own validation/error handling nicely.

This is a follow up to e4350bb966

app/assets/javascripts/discourse/app/components/uppy-backup-uploader.js

@@ -7,6 +7,7 @@ export default Component.extend(UppyUploadMixin, {
   tagName: "span",
   type: "backup",
   useMultipartUploadsIfAvailable: true,
+  uploadRootPath: "/admin/backups",
 
   @discourseComputed("uploading", "uploadProgress")
   uploadButtonText(uploading, progress) {

app/assets/javascripts/discourse/app/mixins/composer-upload-uppy.js

@@ -33,6 +33,7 @@ import bootbox from "bootbox";
 // functionality and event binding.
 //
 export default Mixin.create(ExtendableUploader, UppyS3Multipart, {
+  uploadRootPath: "/uploads",
   uploadTargetBound: false,
 
   @observes("composerModel.uploadCancelled")

app/assets/javascripts/discourse/app/mixins/uppy-s3-multipart.js

@@ -1,4 +1,5 @@
 import Mixin from "@ember/object/mixin";
+import getUrl from "discourse-common/lib/get-url";
 import { bind } from "discourse-common/utils/decorators";
 import { Promise } from "rsvp";
 import { ajax } from "discourse/lib/ajax";
@@ -50,7 +51,7 @@ export default Mixin.create({
       data.metadata = { "sha1-checksum": file.meta.sha1_checksum };
     }
 
-    return ajax("/uploads/create-multipart.json", {
+    return ajax(getUrl(`${this.uploadRootPath}/create-multipart.json`), {
       type: "POST",
       data,
       // uppy is inconsistent, an error here fires the upload-error event
@@ -70,13 +71,16 @@ export default Mixin.create({
     if (file.preparePartsRetryAttempts === undefined) {
       file.preparePartsRetryAttempts = 0;
     }
-    return ajax("/uploads/batch-presign-multipart-parts.json", {
+    return ajax(
+      getUrl(`${this.uploadRootPath}/batch-presign-multipart-parts.json`),
+      {
         type: "POST",
         data: {
           part_numbers: partData.partNumbers,
           unique_identifier: file.meta.unique_identifier,
         },
-    })
+      }
+    )
       .then((data) => {
         if (file.preparePartsRetryAttempts) {
           delete file.preparePartsRetryAttempts;
@@ -122,7 +126,7 @@ export default Mixin.create({
     const parts = data.parts.map((part) => {
       return { part_number: part.PartNumber, etag: part.ETag };
     });
-    return ajax("/uploads/complete-multipart.json", {
+    return ajax(getUrl(`${this.uploadRootPath}/complete-multipart.json`), {
       type: "POST",
       contentType: "application/json",
       data: JSON.stringify({
@@ -155,7 +159,7 @@ export default Mixin.create({
       return;
     }
 
-    return ajax("/uploads/abort-multipart.json", {
+    return ajax(getUrl(`${this.uploadRootPath}/abort-multipart.json`), {
       type: "POST",
       data: {
         external_upload_identifier: uploadId,

app/assets/javascripts/discourse/app/mixins/uppy-upload.js

@@ -27,6 +27,7 @@ export default Mixin.create(UppyS3Multipart, {
   autoStartUploads: true,
   _inProgressUploads: 0,
   id: null,
+  uploadRootPath: "/uploads",
 
   uploadDone() {
     warn("You should implement `uploadDone`", {
@@ -223,7 +224,7 @@ export default Mixin.create(UppyS3Multipart, {
           data.metadata = { "sha1-checksum": file.meta.sha1_checksum };
         }
 
-        return ajax(getUrl("/uploads/generate-presigned-put"), {
+        return ajax(getUrl(`${this.uploadRootPath}/generate-presigned-put`), {
           type: "POST",
           data,
         })
@@ -277,7 +278,7 @@ export default Mixin.create(UppyS3Multipart, {
   },
 
   _completeExternalUpload(file) {
-    return ajax(getUrl("/uploads/complete-external-upload"), {
+    return ajax(getUrl(`${this.uploadRootPath}/complete-external-upload`), {
       type: "POST",
       data: deepMerge(
         { unique_identifier: file.meta.uniqueUploadIdentifier },

app/controllers/admin/backups_controller.rb

@@ -4,6 +4,8 @@ require "backup_restore"
 require "backup_restore/backup_store"
 
 class Admin::BackupsController < Admin::AdminController
+  include ExternalUploadHelpers
+
   before_action :ensure_backups_enabled
   skip_before_action :check_xhr, only: [:index, :show, :logs, :check_backup_chunk, :upload_backup_chunk]
 
@@ -234,4 +236,24 @@ class Admin::BackupsController < Admin::AdminController
   def render_error(message_key)
     render json: failed_json.merge(message: I18n.t(message_key))
   end
+
+  def validate_before_create_multipart(file_name:, file_size:, upload_type:)
+    raise ExternalUploadHelpers::ExternalUploadValidationError.new(I18n.t("backup.backup_file_should_be_tar_gz")) unless valid_extension?(file_name)
+    raise ExternalUploadHelpers::ExternalUploadValidationError.new(I18n.t("backup.invalid_filename")) unless valid_filename?(file_name)
+  end
+
+  def self.serialize_upload(_upload)
+    {} # noop, the backup does not create an upload record
+  end
+
+  def create_direct_multipart_upload
+    begin
+      yield
+    rescue BackupRestore::BackupStore::StorageError => err
+      message = debug_upload_error(err, I18n.t("upload.create_multipart_failure", additional_detail: err.message))
+      raise ExternalUploadHelpers::ExternalUploadValidationError.new(message)
+    rescue BackupRestore::BackupStore::BackupFileExists
+      raise ExternalUploadHelpers::ExternalUploadValidationError.new(I18n.t("backup.file_exists"))
+    end
+  end
 end

app/controllers/uploads_controller.rb

@@ -3,36 +3,17 @@
 require "mini_mime"
 
 class UploadsController < ApplicationController
+  include ExternalUploadHelpers
+
   requires_login except: [:show, :show_short, :show_secure]
 
   skip_before_action :preload_json, :check_xhr, :redirect_to_login_if_required, only: [:show, :show_short, :show_secure]
   protect_from_forgery except: :show
 
   before_action :is_asset_path, :apply_cdn_headers, only: [:show, :show_short, :show_secure]
-  before_action :external_store_check, only: [
+  before_action :external_store_check, only: [:show_secure]
-    :show_secure,
-    :generate_presigned_put,
-    :complete_external_upload,
-    :create_multipart,
-    :batch_presign_multipart_parts,
-    :abort_multipart,
-    :complete_multipart
-  ]
-  before_action :direct_s3_uploads_check, only: [
-    :generate_presigned_put,
-    :complete_external_upload,
-    :create_multipart,
-    :batch_presign_multipart_parts,
-    :abort_multipart,
-    :complete_multipart
-  ]
-  before_action :can_upload_external?, only: [:create_multipart, :generate_presigned_put]
 
   SECURE_REDIRECT_GRACE_SECONDS = 5
-  PRESIGNED_PUT_RATE_LIMIT_PER_MINUTE = 10
-  CREATE_MULTIPART_RATE_LIMIT_PER_MINUTE = 10
-  COMPLETE_MULTIPART_RATE_LIMIT_PER_MINUTE = 10
-  BATCH_PRESIGN_RATE_LIMIT_PER_MINUTE = 10
 
   def create
     # capture current user for block later on
@@ -208,285 +189,25 @@ class UploadsController < ApplicationController
     }
   end
 
-  def generate_presigned_put
-    RateLimiter.new(
-      current_user, "generate-presigned-put-upload-stub", PRESIGNED_PUT_RATE_LIMIT_PER_MINUTE, 1.minute
-    ).performed!
-
-    file_name = params.require(:file_name)
-    file_size = params.require(:file_size).to_i
-    type = params.require(:type)
-
-    if file_size_too_big?(file_name, file_size)
-      return render_json_error(
-        I18n.t("upload.attachments.too_large_humanized", max_size: ActiveSupport::NumberHelper.number_to_human_size(SiteSetting.max_attachment_size_kb.kilobytes)),
-        status: 422
-      )
-    end
-
-    external_upload_data = ExternalUploadManager.create_direct_upload(
-      current_user: current_user,
-      file_name: file_name,
-      file_size: file_size,
-      upload_type: type,
-      metadata: parse_allowed_metadata(params[:metadata])
-    )
-
-    render json: external_upload_data
-  end
-
-  def complete_external_upload
-    unique_identifier = params.require(:unique_identifier)
-    external_upload_stub = ExternalUploadStub.find_by(
-      unique_identifier: unique_identifier, created_by: current_user
-    )
-    return render_404 if external_upload_stub.blank?
-
-    complete_external_upload_via_manager(external_upload_stub)
-  end
-
-  def complete_external_upload_via_manager(external_upload_stub)
-    opts = {
-      for_private_message: params[:for_private_message]&.to_s == "true",
-      for_site_setting: params[:for_site_setting]&.to_s == "true",
-      pasted: params[:pasted]&.to_s == "true",
-    }
-
-    external_upload_manager = ExternalUploadManager.new(external_upload_stub, opts)
-    hijack do
-      begin
-        upload = external_upload_manager.transform!
-
-        if upload.errors.empty?
-          response_serialized = external_upload_stub.upload_type != "backup" ? UploadsController.serialize_upload(upload) : {}
-          external_upload_stub.destroy!
-          render json: response_serialized, status: 200
-        else
-          render_json_error(upload.errors.to_hash.values.flatten, status: 422)
-        end
-      rescue ExternalUploadManager::SizeMismatchError => err
-        render_json_error(
-          debug_upload_error(err, "upload.size_mismatch_failure", additional_detail: err.message),
-          status: 422
-        )
-      rescue ExternalUploadManager::ChecksumMismatchError => err
-        render_json_error(
-          debug_upload_error(err, "upload.checksum_mismatch_failure", additional_detail: err.message),
-          status: 422
-        )
-      rescue ExternalUploadManager::CannotPromoteError => err
-        render_json_error(
-          debug_upload_error(err, "upload.cannot_promote_failure", additional_detail: err.message),
-          status: 422
-        )
-      rescue ExternalUploadManager::DownloadFailedError, Aws::S3::Errors::NotFound => err
-        render_json_error(
-          debug_upload_error(err, "upload.download_failure", additional_detail: err.message),
-          status: 422
-        )
-      rescue => err
-        Discourse.warn_exception(
-          err, message: "Complete external upload failed unexpectedly for user #{current_user.id}"
-        )
-
-        render_json_error(I18n.t("upload.failed"), status: 422)
-      end
-    end
-  end
-
-  def create_multipart
-    RateLimiter.new(
-      current_user, "create-multipart-upload", CREATE_MULTIPART_RATE_LIMIT_PER_MINUTE, 1.minute
-    ).performed!
-
-    file_name = params.require(:file_name)
-    file_size = params.require(:file_size).to_i
-    upload_type = params.require(:upload_type)
-
-    if upload_type == "backup"
-      ensure_staff
-      return render_json_error(I18n.t("backup.backup_file_should_be_tar_gz")) unless valid_backup_extension?(file_name)
-      return render_json_error(I18n.t("backup.invalid_filename")) unless valid_backup_filename?(file_name)
-    else
-      if file_size_too_big?(file_name, file_size)
-        return render_json_error(
-          I18n.t("upload.attachments.too_large_humanized", max_size: ActiveSupport::NumberHelper.number_to_human_size(SiteSetting.max_attachment_size_kb.kilobytes)),
-          status: 422
-        )
-      end
-    end
-
-    begin
-      external_upload_data = ExternalUploadManager.create_direct_multipart_upload(
-        current_user: current_user,
-        file_name: file_name,
-        file_size: file_size,
-        upload_type: upload_type,
-        metadata: parse_allowed_metadata(params[:metadata])
-      )
-    rescue Aws::S3::Errors::ServiceError => err
-      return render_json_error(
-        debug_upload_error(err, "upload.create_multipart_failure", additional_detail: err.message),
-        status: 422
-      )
-    rescue BackupRestore::BackupStore::BackupFileExists
-      return render_json_error(I18n.t("backup.file_exists"), status: 422)
-    rescue BackupRestore::BackupStore::StorageError => err
-      return render_json_error(
-        debug_upload_error(err, "upload.create_multipart_failure", additional_detail: err.message),
-        status: 422
-      )
-    end
-
-    render json: external_upload_data
-  end
-
-  def batch_presign_multipart_parts
-    part_numbers = params.require(:part_numbers)
-    unique_identifier = params.require(:unique_identifier)
-
-    RateLimiter.new(
-      current_user, "batch-presign", BATCH_PRESIGN_RATE_LIMIT_PER_MINUTE, 1.minute
-    ).performed!
-
-    part_numbers = part_numbers.map do |part_number|
-      validate_part_number(part_number)
-    end
-
-    external_upload_stub = ExternalUploadStub.find_by(
-      unique_identifier: unique_identifier, created_by: current_user
-    )
-    return render_404 if external_upload_stub.blank?
-
-    if !multipart_upload_exists?(external_upload_stub)
-      return render_404
-    end
-
-    store = multipart_store(external_upload_stub.upload_type)
-
-    presigned_urls = {}
-    part_numbers.each do |part_number|
-      presigned_urls[part_number] = store.presign_multipart_part(
-        upload_id: external_upload_stub.external_upload_identifier,
-        key: external_upload_stub.key,
-        part_number: part_number
-      )
-    end
-
-    render json: { presigned_urls: presigned_urls }
-  end
-
-  def validate_part_number(part_number)
-    part_number = part_number.to_i
-    if !part_number.between?(1, 10000)
-      raise Discourse::InvalidParameters.new(
-        "Each part number should be between 1 and 10000"
-      )
-    end
-    part_number
-  end
-
-  def multipart_upload_exists?(external_upload_stub)
-    store = multipart_store(external_upload_stub.upload_type)
-    begin
-      store.list_multipart_parts(
-        upload_id: external_upload_stub.external_upload_identifier,
-        key: external_upload_stub.key,
-        max_parts: 1
-      )
-    rescue Aws::S3::Errors::NoSuchUpload => err
-      debug_upload_error(err, "upload.external_upload_not_found", { additional_detail: "path: #{external_upload_stub.key}" })
-      return false
-    end
-    true
-  end
-
-  def abort_multipart
-    external_upload_identifier = params.require(:external_upload_identifier)
-    external_upload_stub = ExternalUploadStub.find_by(
-      external_upload_identifier: external_upload_identifier
-    )
-
-    # The stub could have already been deleted by an earlier error via
-    # ExternalUploadManager, so we consider this a great success if the
-    # stub is already gone.
-    return render json: success_json if external_upload_stub.blank?
-
-    return render_404 if external_upload_stub.created_by_id != current_user.id
-    store = multipart_store(external_upload_stub.upload_type)
-
-    begin
-      store.abort_multipart(
-        upload_id: external_upload_stub.external_upload_identifier,
-        key: external_upload_stub.key
-      )
-    rescue Aws::S3::Errors::ServiceError => err
-      return render_json_error(
-        debug_upload_error(err, "upload.abort_multipart_failure", additional_detail: "external upload stub id: #{external_upload_stub.id}"),
-        status: 422
-      )
-    end
-
-    external_upload_stub.destroy!
-
-    render json: success_json
-  end
-
-  def complete_multipart
-    unique_identifier = params.require(:unique_identifier)
-    parts = params.require(:parts)
-
-    RateLimiter.new(
-      current_user, "complete-multipart-upload", COMPLETE_MULTIPART_RATE_LIMIT_PER_MINUTE, 1.minute
-    ).performed!
-
-    external_upload_stub = ExternalUploadStub.find_by(
-      unique_identifier: unique_identifier, created_by: current_user
-    )
-    return render_404 if external_upload_stub.blank?
-
-    if !multipart_upload_exists?(external_upload_stub)
-      return render_404
-    end
-
-    store = multipart_store(external_upload_stub.upload_type)
-    parts = parts.map do |part|
-      part_number = part[:part_number]
-      etag = part[:etag]
-      part_number = validate_part_number(part_number)
-
-      if etag.blank?
-        raise Discourse::InvalidParameters.new("All parts must have an etag and a valid part number")
-      end
-
-      # this is done so it's an array of hashes rather than an array of
-      # ActionController::Parameters
-      { part_number: part_number, etag: etag }
-    end.sort_by do |part|
-      part[:part_number]
-    end
-
-    begin
-      complete_response = store.complete_multipart(
-        upload_id: external_upload_stub.external_upload_identifier,
-        key: external_upload_stub.key,
-        parts: parts
-      )
-    rescue Aws::S3::Errors::ServiceError => err
-      return render_json_error(
-        debug_upload_error(err, "upload.complete_multipart_failure", additional_detail: "external upload stub id: #{external_upload_stub.id}"),
-        status: 422
-      )
-    end
-
-    complete_external_upload_via_manager(external_upload_stub)
-  end
-
   protected
 
-  def multipart_store(upload_type)
+  def validate_before_create_multipart(file_name:, file_size:, upload_type:)
-    ensure_staff if upload_type == "backup"
+    validate_file_size(file_name: file_name, file_size: file_size)
-    ExternalUploadManager.store_for_upload_type(upload_type)
+  end
+
+  def validate_before_create_direct_upload(file_name:, file_size:, upload_type:)
+    validate_file_size(file_name: file_name, file_size: file_size)
+  end
+
+  def validate_file_size(file_name:, file_size:)
+    if file_size_too_big?(file_name, file_size)
+      raise ExternalUploadValidationError.new(
+        I18n.t(
+          "upload.attachments.too_large_humanized",
+          max_size: ActiveSupport::NumberHelper.number_to_human_size(SiteSetting.max_attachment_size_kb.kilobytes)
+        )
+      )
+    end
   end
 
   def force_download?
@@ -497,10 +218,6 @@ class UploadsController < ApplicationController
     raise Discourse::InvalidParameters.new("XHR not allowed")
   end
 
-  def render_404
-    raise Discourse::NotFound
-  end
-
   def self.serialize_upload(data)
     # as_json.as_json is not a typo... as_json in AM serializer returns keys as symbols, we need them
     # as strings here
@@ -556,18 +273,6 @@ class UploadsController < ApplicationController
 
   private
 
-  def external_store_check
-    return render_404 if !Discourse.store.external?
-  end
-
-  def direct_s3_uploads_check
-    return render_404 if !SiteSetting.enable_direct_s3_uploads
-  end
-
-  def can_upload_external?
-    raise Discourse::InvalidAccess if !guardian.can_upload_external?
-  end
-
   # We can pre-emptively check size for attachments, but not for images
   # as they may be further reduced in size by UploadCreator (at this point
   # they may have already been reduced in size by preprocessors)
@@ -593,29 +298,12 @@ class UploadsController < ApplicationController
     send_file(file_path, opts)
   end
 
-  def debug_upload_error(err, translation_key, translation_params = {})
+  def create_direct_multipart_upload
-    return if !SiteSetting.enable_upload_debug_mode
+    begin
-    message = I18n.t(translation_key, translation_params)
+      yield
-    Discourse.warn_exception(err, message: message)
+    rescue Aws::S3::Errors::ServiceError => err
-    Rails.env.development? ? message : I18n.t("upload.failed")
+      message = debug_upload_error(err, I18n.t("upload.create_multipart_failure", additional_detail: err.message))
-  end
+      raise ExternalUploadHelpers::ExternalUploadValidationError.new(message)
-
+    end
-  # don't want people posting arbitrary S3 metadata so we just take the
-  # one we need. all of these will be converted to x-amz-meta- metadata
-  # fields in S3 so it's best to use dashes in the names for consistency
-  #
-  # this metadata is baked into the presigned url and is not altered when
-  # sending the PUT from the clientside to the presigned url
-  def parse_allowed_metadata(metadata)
-    return if metadata.blank?
-    metadata.permit("sha1-checksum").to_h
-  end
-
-  def valid_backup_extension?(filename)
-    /\.(tar\.gz|t?gz)$/i =~ filename
-  end
-
-  def valid_backup_filename?(filename)
-    !!(/^[a-zA-Z0-9\._\-]+$/ =~ filename)
   end
 end

config/routes.rb

@@ -304,6 +304,12 @@ Discourse::Application.routes.draw do
           post "restore" => "backups#restore", constraints: { id: RouteFormat.backup }
         end
         collection do
+          # multipart uploads
+          post "create-multipart" => "backups#create_multipart", format: :json
+          post "complete-multipart" => "backups#complete_multipart", format: :json
+          post "abort-multipart" => "backups#abort_multipart", format: :json
+          post "batch-presign-multipart-parts" => "backups#batch_presign_multipart_parts", format: :json
+
           get "logs" => "backups#logs"
           get "status" => "backups#status"
           delete "cancel" => "backups#cancel"

lib/external_upload_helpers.rb

@@ -0,0 +1,347 @@
+# frozen_string_literal: true
+
+# Extends controllers with the methods required to do direct
+# external uploads.
+module ExternalUploadHelpers
+  extend ActiveSupport::Concern
+
+  class ExternalUploadValidationError < StandardError; end
+
+  PRESIGNED_PUT_RATE_LIMIT_PER_MINUTE = 10
+  CREATE_MULTIPART_RATE_LIMIT_PER_MINUTE = 10
+  COMPLETE_MULTIPART_RATE_LIMIT_PER_MINUTE = 10
+  BATCH_PRESIGN_RATE_LIMIT_PER_MINUTE = 10
+
+  included do
+    before_action :external_store_check, only: [
+      :generate_presigned_put,
+      :complete_external_upload,
+      :create_multipart,
+      :batch_presign_multipart_parts,
+      :abort_multipart,
+      :complete_multipart
+    ]
+    before_action :direct_s3_uploads_check, only: [
+      :generate_presigned_put,
+      :complete_external_upload,
+      :create_multipart,
+      :batch_presign_multipart_parts,
+      :abort_multipart,
+      :complete_multipart
+    ]
+    before_action :can_upload_external?, only: [:create_multipart, :generate_presigned_put]
+  end
+
+  def generate_presigned_put
+    RateLimiter.new(
+      current_user, "generate-presigned-put-upload-stub", ExternalUploadHelpers::PRESIGNED_PUT_RATE_LIMIT_PER_MINUTE, 1.minute
+    ).performed!
+
+    file_name = params.require(:file_name)
+    file_size = params.require(:file_size).to_i
+    type = params.require(:type)
+
+    begin
+      validate_before_create_direct_upload(
+        file_name: file_name,
+        file_size: file_size,
+        upload_type: type
+      )
+    rescue ExternalUploadValidationError => err
+      return render_json_error(err.message, status: 422)
+    end
+
+    external_upload_data = ExternalUploadManager.create_direct_upload(
+      current_user: current_user,
+      file_name: file_name,
+      file_size: file_size,
+      upload_type: type,
+      metadata: parse_allowed_metadata(params[:metadata])
+    )
+
+    render json: external_upload_data
+  end
+
+  def complete_external_upload
+    unique_identifier = params.require(:unique_identifier)
+    external_upload_stub = ExternalUploadStub.find_by(
+      unique_identifier: unique_identifier, created_by: current_user
+    )
+    return render_404 if external_upload_stub.blank?
+
+    complete_external_upload_via_manager(external_upload_stub)
+  end
+
+  def create_multipart
+    RateLimiter.new(
+      current_user, "create-multipart-upload", ExternalUploadHelpers::CREATE_MULTIPART_RATE_LIMIT_PER_MINUTE, 1.minute
+    ).performed!
+
+    file_name = params.require(:file_name)
+    file_size = params.require(:file_size).to_i
+    upload_type = params.require(:upload_type)
+
+    begin
+      validate_before_create_multipart(
+        file_name: file_name,
+        file_size: file_size,
+        upload_type: upload_type
+      )
+    rescue ExternalUploadValidationError => err
+      return render_json_error(err.message, status: 422)
+    end
+
+    begin
+      external_upload_data = create_direct_multipart_upload do
+        ExternalUploadManager.create_direct_multipart_upload(
+          current_user: current_user,
+          file_name: file_name,
+          file_size: file_size,
+          upload_type: upload_type,
+          metadata: parse_allowed_metadata(params[:metadata])
+        )
+      end
+    rescue ExternalUploadHelpers::ExternalUploadValidationError => err
+      return render_json_error(err.message, status: 422)
+    end
+
+    render json: external_upload_data
+  end
+
+  def batch_presign_multipart_parts
+    part_numbers = params.require(:part_numbers)
+    unique_identifier = params.require(:unique_identifier)
+
+    RateLimiter.new(
+      current_user, "batch-presign", ExternalUploadHelpers::BATCH_PRESIGN_RATE_LIMIT_PER_MINUTE, 1.minute
+    ).performed!
+
+    part_numbers = part_numbers.map do |part_number|
+      validate_part_number(part_number)
+    end
+
+    external_upload_stub = ExternalUploadStub.find_by(
+      unique_identifier: unique_identifier, created_by: current_user
+    )
+    return render_404 if external_upload_stub.blank?
+
+    if !multipart_upload_exists?(external_upload_stub)
+      return render_404
+    end
+
+    store = multipart_store(external_upload_stub.upload_type)
+
+    presigned_urls = {}
+    part_numbers.each do |part_number|
+      presigned_urls[part_number] = store.presign_multipart_part(
+        upload_id: external_upload_stub.external_upload_identifier,
+        key: external_upload_stub.key,
+        part_number: part_number
+      )
+    end
+
+    render json: { presigned_urls: presigned_urls }
+  end
+
+  def multipart_upload_exists?(external_upload_stub)
+    store = multipart_store(external_upload_stub.upload_type)
+    begin
+      store.list_multipart_parts(
+        upload_id: external_upload_stub.external_upload_identifier,
+        key: external_upload_stub.key,
+        max_parts: 1
+      )
+    rescue Aws::S3::Errors::NoSuchUpload => err
+      debug_upload_error(err, I18n.t("upload.external_upload_not_found", additional_detail: "path: #{external_upload_stub.key}"))
+      return false
+    end
+    true
+  end
+
+  def abort_multipart
+    external_upload_identifier = params.require(:external_upload_identifier)
+    external_upload_stub = ExternalUploadStub.find_by(
+      external_upload_identifier: external_upload_identifier
+    )
+
+    # The stub could have already been deleted by an earlier error via
+    # ExternalUploadManager, so we consider this a great success if the
+    # stub is already gone.
+    return render json: success_json if external_upload_stub.blank?
+
+    return render_404 if external_upload_stub.created_by_id != current_user.id
+    store = multipart_store(external_upload_stub.upload_type)
+
+    begin
+      store.abort_multipart(
+        upload_id: external_upload_stub.external_upload_identifier,
+        key: external_upload_stub.key
+      )
+    rescue Aws::S3::Errors::ServiceError => err
+      return render_json_error(
+        debug_upload_error(err, I18n.t("upload.abort_multipart_failure", additional_detail: "external upload stub id: #{external_upload_stub.id}")),
+        status: 422
+      )
+    end
+
+    external_upload_stub.destroy!
+
+    render json: success_json
+  end
+
+  def complete_multipart
+    unique_identifier = params.require(:unique_identifier)
+    parts = params.require(:parts)
+
+    RateLimiter.new(
+      current_user, "complete-multipart-upload", ExternalUploadHelpers::COMPLETE_MULTIPART_RATE_LIMIT_PER_MINUTE, 1.minute
+    ).performed!
+
+    external_upload_stub = ExternalUploadStub.find_by(
+      unique_identifier: unique_identifier, created_by: current_user
+    )
+    return render_404 if external_upload_stub.blank?
+
+    if !multipart_upload_exists?(external_upload_stub)
+      return render_404
+    end
+
+    store = multipart_store(external_upload_stub.upload_type)
+    parts = parts.map do |part|
+      part_number = part[:part_number]
+      etag = part[:etag]
+      part_number = validate_part_number(part_number)
+
+      if etag.blank?
+        raise Discourse::InvalidParameters.new("All parts must have an etag and a valid part number")
+      end
+
+      # this is done so it's an array of hashes rather than an array of
+      # ActionController::Parameters
+      { part_number: part_number, etag: etag }
+    end.sort_by do |part|
+      part[:part_number]
+    end
+
+    begin
+      complete_response = store.complete_multipart(
+        upload_id: external_upload_stub.external_upload_identifier,
+        key: external_upload_stub.key,
+        parts: parts
+      )
+    rescue Aws::S3::Errors::ServiceError => err
+      return render_json_error(
+        debug_upload_error(err, I18n.t("upload.complete_multipart_failure", additional_detail: "external upload stub id: #{external_upload_stub.id}")),
+        status: 422
+      )
+    end
+
+    complete_external_upload_via_manager(external_upload_stub)
+  end
+
+  private
+
+  def complete_external_upload_via_manager(external_upload_stub)
+    opts = {
+      for_private_message: params[:for_private_message]&.to_s == "true",
+      for_site_setting: params[:for_site_setting]&.to_s == "true",
+      pasted: params[:pasted]&.to_s == "true",
+    }
+
+    external_upload_manager = ExternalUploadManager.new(external_upload_stub, opts)
+    hijack do
+      begin
+        upload = external_upload_manager.transform!
+
+        if upload.errors.empty?
+          response_serialized = self.class.serialize_upload(upload)
+          external_upload_stub.destroy!
+          render json: response_serialized, status: 200
+        else
+          render_json_error(upload.errors.to_hash.values.flatten, status: 422)
+        end
+      rescue ExternalUploadManager::SizeMismatchError => err
+        render_json_error(
+          debug_upload_error(err, I18n.t("upload.size_mismatch_failure", additional_detail: err.message)),
+          status: 422
+        )
+      rescue ExternalUploadManager::ChecksumMismatchError => err
+        render_json_error(
+          debug_upload_error(err, I18n.t("upload.checksum_mismatch_failure", additional_detail: err.message)),
+          status: 422
+        )
+      rescue ExternalUploadManager::CannotPromoteError => err
+        render_json_error(
+          debug_upload_error(err, I18n.t("upload.cannot_promote_failure", additional_detail: err.message)),
+          status: 422
+        )
+      rescue ExternalUploadManager::DownloadFailedError, Aws::S3::Errors::NotFound => err
+        render_json_error(
+          debug_upload_error(err, I18n.t("upload.download_failure", additional_detail: err.message)),
+          status: 422
+        )
+      rescue => err
+        Discourse.warn_exception(
+          err, message: "Complete external upload failed unexpectedly for user #{current_user.id}"
+        )
+
+        render_json_error(I18n.t("upload.failed"), status: 422)
+      end
+    end
+  end
+
+  def validate_before_create_direct_upload(file_name:, file_size:, upload_type:)
+    # noop, should be overridden
+  end
+
+  def validate_before_create_multipart(file_name:, file_size:, upload_type:)
+    # noop, should be overridden
+  end
+
+  def validate_part_number(part_number)
+    part_number = part_number.to_i
+    if !part_number.between?(1, 10000)
+      raise Discourse::InvalidParameters.new(
+        "Each part number should be between 1 and 10000"
+      )
+    end
+    part_number
+  end
+
+  def debug_upload_error(err, friendly_message)
+    return if !SiteSetting.enable_upload_debug_mode
+    Discourse.warn_exception(err, message: friendly_message)
+    Rails.env.development? ? friendly_message : I18n.t("upload.failed")
+  end
+
+  def multipart_store(upload_type)
+    ExternalUploadManager.store_for_upload_type(upload_type)
+  end
+
+  def external_store_check
+    return render_404 if !Discourse.store.external?
+  end
+
+  def direct_s3_uploads_check
+    return render_404 if !SiteSetting.enable_direct_s3_uploads
+  end
+
+  def can_upload_external?
+    raise Discourse::InvalidAccess if !guardian.can_upload_external?
+  end
+
+  # don't want people posting arbitrary S3 metadata so we just take the
+  # one we need. all of these will be converted to x-amz-meta- metadata
+  # fields in S3 so it's best to use dashes in the names for consistency
+  #
+  # this metadata is baked into the presigned url and is not altered when
+  # sending the PUT from the clientside to the presigned url
+  def parse_allowed_metadata(metadata)
+    return if metadata.blank?
+    metadata.permit("sha1-checksum").to_h
+  end
+
+  def render_404
+    raise Discourse::NotFound
+  end
+end

spec/requests/admin/backups_controller_spec.rb

@@ -416,4 +416,120 @@ RSpec.describe Admin::BackupsController do
       expect(response).to be_not_found
     end
   end
+
+  describe "S3 multipart uploads" do
+    let(:upload_type) { "backup" }
+    let(:test_bucket_prefix) { "test_#{ENV['TEST_ENV_NUMBER'].presence || '0'}" }
+    let(:backup_file_exists_response) { { status: 404 } }
+    let(:mock_multipart_upload_id) { "ibZBv_75gd9r8lH_gqXatLdxMVpAlj6CFTR.OwyF3953YdwbcQnMA2BLGn8Lx12fQNICtMw5KyteFeHw.Sjng--" }
+
+    before do
+      setup_s3
+      SiteSetting.enable_direct_s3_uploads = true
+      SiteSetting.s3_backup_bucket = "s3-backup-bucket"
+      SiteSetting.backup_location = BackupLocationSiteSetting::S3
+      stub_request(:head, "https://s3-backup-bucket.s3.us-west-1.amazonaws.com/").to_return(status: 200, body: "", headers: {})
+      stub_request(:head, "https://s3-backup-bucket.s3.us-west-1.amazonaws.com/default/test.tar.gz").to_return(
+        backup_file_exists_response
+      )
+    end
+
+    context "when the user is not admin" do
+      before do
+        admin.update(admin: false)
+      end
+
+      it "errors with invalid access error" do
+        post "/admin/backups/create-multipart.json", params: {
+          file_name: "test.tar.gz",
+          upload_type: upload_type,
+          file_size: 4098
+        }
+        expect(response.status).to eq(404)
+      end
+    end
+
+    context "when the user is admin" do
+      def stub_create_multipart_backup_request
+        BackupRestore::S3BackupStore.any_instance.stubs(:temporary_upload_path).returns(
+          "temp/default/#{test_bucket_prefix}/28fccf8259bbe75b873a2bd2564b778c/2u98j832nx93272x947823.gz"
+        )
+        create_multipart_result = <<~BODY
+        <?xml version=\"1.0\" encoding=\"UTF-8\"?>\n
+        <InitiateMultipartUploadResult>
+           <Bucket>s3-backup-bucket</Bucket>
+           <Key>temp/default/#{test_bucket_prefix}/28fccf8259bbe75b873a2bd2564b778c/2u98j832nx93272x947823.gz</Key>
+           <UploadId>#{mock_multipart_upload_id}</UploadId>
+        </InitiateMultipartUploadResult>
+        BODY
+        stub_request(:post, "https://s3-backup-bucket.s3.us-west-1.amazonaws.com/temp/default/#{test_bucket_prefix}/28fccf8259bbe75b873a2bd2564b778c/2u98j832nx93272x947823.gz?uploads").
+          to_return(status: 200, body: create_multipart_result)
+      end
+
+      it "creates the multipart upload" do
+        stub_create_multipart_backup_request
+        post "/admin/backups/create-multipart.json", params: {
+          file_name: "test.tar.gz",
+          upload_type: upload_type,
+          file_size: 4098
+        }
+        expect(response.status).to eq(200)
+        result = response.parsed_body
+
+        external_upload_stub = ExternalUploadStub.where(
+          unique_identifier: result["unique_identifier"],
+          original_filename: "test.tar.gz",
+          created_by: admin,
+          upload_type: upload_type,
+          key: result["key"],
+          multipart: true
+        )
+        expect(external_upload_stub.exists?).to eq(true)
+      end
+
+      context "when backup of same filename already exists" do
+        let(:backup_file_exists_response) { { status: 200, body: "" } }
+
+        it "throws an error" do
+          post "/admin/backups/create-multipart.json", params: {
+            file_name: "test.tar.gz",
+            upload_type: upload_type,
+            file_size: 4098
+          }
+          expect(response.status).to eq(422)
+          expect(response.parsed_body["errors"]).to include(
+            I18n.t("backup.file_exists")
+          )
+        end
+      end
+
+      context "when filename is invalid" do
+        it "throws an error" do
+          post "/admin/backups/create-multipart.json", params: {
+            file_name: "blah $$##.tar.gz",
+            upload_type: upload_type,
+            file_size: 4098
+          }
+          expect(response.status).to eq(422)
+          expect(response.parsed_body["errors"]).to include(
+            I18n.t("backup.invalid_filename")
+          )
+        end
+      end
+
+      context "when extension is invalid" do
+        it "throws an error" do
+          post "/admin/backups/create-multipart.json", params: {
+            file_name: "test.png",
+            upload_type: upload_type,
+            file_size: 4098
+          }
+          expect(response.status).to eq(422)
+          expect(response.parsed_body["errors"]).to include(
+            I18n.t("backup.backup_file_should_be_tar_gz")
+          )
+        end
+      end
+    end
+  end
 end

spec/requests/uploads_controller_spec.rb

@@ -764,7 +764,7 @@ describe UploadsController do
         RateLimiter.enable
         RateLimiter.clear_all!
 
-        stub_const(UploadsController, "PRESIGNED_PUT_RATE_LIMIT_PER_MINUTE", 1) do
+        stub_const(ExternalUploadHelpers, "PRESIGNED_PUT_RATE_LIMIT_PER_MINUTE", 1) do
           post "/uploads/generate-presigned-put.json", params: { file_name: "test.png", type: "card_background", file_size: 1024 }
           post "/uploads/generate-presigned-put.json", params: { file_name: "test.png", type: "card_background", file_size: 1024 }
         end
@@ -793,8 +793,6 @@ describe UploadsController do
         sign_in(user)
         SiteSetting.enable_direct_s3_uploads = true
         setup_s3
-        SiteSetting.s3_backup_bucket = "s3-backup-bucket"
-        SiteSetting.backup_location = BackupLocationSiteSetting::S3
       end
 
       it "errors if the correct params are not provided" do
@@ -902,7 +900,7 @@ describe UploadsController do
         RateLimiter.clear_all!
 
         stub_create_multipart_request
-        stub_const(UploadsController, "CREATE_MULTIPART_RATE_LIMIT_PER_MINUTE", 1) do
+        stub_const(ExternalUploadHelpers, "CREATE_MULTIPART_RATE_LIMIT_PER_MINUTE", 1) do
           post "/uploads/create-multipart.json", params: {
             file_name: "test.png",
             upload_type: "composer",
@@ -918,88 +916,6 @@ describe UploadsController do
           expect(response.status).to eq(429)
         end
       end
-
-      context "when the upload_type is backup" do
-        let(:upload_type) { "backup" }
-        let(:backup_file_exists_response) { { status: 404 } }
-
-        before do
-          stub_request(:head, "https://s3-backup-bucket.s3.us-west-1.amazonaws.com/").to_return(status: 200, body: "", headers: {})
-          stub_request(:head, "https://s3-backup-bucket.s3.us-west-1.amazonaws.com/default/test.tar.gz").to_return(
-            backup_file_exists_response
-          )
-        end
-
-        context "when the user is not admin" do
-          it "errors with invalid access error" do
-            post "/uploads/create-multipart.json", params: {
-              file_name: "test.tar.gz",
-              upload_type: upload_type,
-              file_size: 4098
-            }
-            expect(response.status).to eq(403)
-          end
-        end
-
-        context "when the user is admin" do
-          before do
-            user.update(admin: true)
-          end
-
-          def stub_create_multipart_backup_request
-            BackupRestore::S3BackupStore.any_instance.stubs(:temporary_upload_path).returns(
-              "temp/default/#{test_bucket_prefix}/28fccf8259bbe75b873a2bd2564b778c/2u98j832nx93272x947823.gz"
-            )
-            create_multipart_result = <<~BODY
-        <?xml version=\"1.0\" encoding=\"UTF-8\"?>\n
-        <InitiateMultipartUploadResult>
-           <Bucket>s3-backup-bucket</Bucket>
-           <Key>temp/default/#{test_bucket_prefix}/28fccf8259bbe75b873a2bd2564b778c/2u98j832nx93272x947823.gz</Key>
-           <UploadId>#{mock_multipart_upload_id}</UploadId>
-        </InitiateMultipartUploadResult>
-            BODY
-            stub_request(:post, "https://s3-backup-bucket.s3.us-west-1.amazonaws.com/temp/default/#{test_bucket_prefix}/28fccf8259bbe75b873a2bd2564b778c/2u98j832nx93272x947823.gz?uploads").
-              to_return(status: 200, body: create_multipart_result)
-          end
-
-          it "creates the multipart upload" do
-            stub_create_multipart_backup_request
-            post "/uploads/create-multipart.json", params: {
-              file_name: "test.tar.gz",
-              upload_type: upload_type,
-              file_size: 4098
-            }
-            expect(response.status).to eq(200)
-            result = response.parsed_body
-
-            external_upload_stub = ExternalUploadStub.where(
-              unique_identifier: result["unique_identifier"],
-              original_filename: "test.tar.gz",
-              created_by: user,
-              upload_type: upload_type,
-              key: result["key"],
-              multipart: true
-            )
-            expect(external_upload_stub.exists?).to eq(true)
-          end
-
-          context "when backup of same filename already exists" do
-            let(:backup_file_exists_response) { { status: 200, body: "" } }
-
-            it "throws an error" do
-              post "/uploads/create-multipart.json", params: {
-                file_name: "test.tar.gz",
-                upload_type: upload_type,
-                file_size: 4098
-              }
-              expect(response.status).to eq(422)
-              expect(response.parsed_body["errors"]).to include(
-                I18n.t("backup.file_exists")
-              )
-            end
-          end
-        end
-      end
     end
 
     context "when the store is not external" do
@@ -1127,7 +1043,7 @@ describe UploadsController do
         RateLimiter.enable
         RateLimiter.clear_all!
 
-        stub_const(UploadsController, "BATCH_PRESIGN_RATE_LIMIT_PER_MINUTE", 1) do
+        stub_const(ExternalUploadHelpers, "BATCH_PRESIGN_RATE_LIMIT_PER_MINUTE", 1) do
           stub_list_multipart_request
           post "/uploads/batch-presign-multipart-parts.json", params: {
             unique_identifier: external_upload_stub.unique_identifier,
@@ -1316,7 +1232,7 @@ describe UploadsController do
         RateLimiter.enable
         RateLimiter.clear_all!
 
-        stub_const(UploadsController, "COMPLETE_MULTIPART_RATE_LIMIT_PER_MINUTE", 1) do
+        stub_const(ExternalUploadHelpers, "COMPLETE_MULTIPART_RATE_LIMIT_PER_MINUTE", 1) do
           post "/uploads/complete-multipart.json", params: {
             unique_identifier: "blah",
             parts: [{ part_number: 1, etag: "test1" }, { part_number: 2, etag: "test2" }]