Download backup on link

ts/background.ts

@@ -1482,6 +1482,12 @@ export async function startApp(): Promise<void> {
         )
       );
 
+      // Now that we authenticated - time to download the backup!
+      if (isBackupEnabled()) {
+        backupsService.start();
+        drop(backupsService.download());
+      }
+
       // Cancel throttled calls to refreshRemoteConfig since our auth changed.
       window.Signal.RemoteConfig.maybeRefreshRemoteConfig.cancel();
       drop(window.Signal.RemoteConfig.maybeRefreshRemoteConfig(server));

ts/services/backups/api.ts

@@ -1,6 +1,7 @@
 // Copyright 2024 Signal Messenger, LLC
 // SPDX-License-Identifier: AGPL-3.0-only
 
+import { type Readable } from 'node:stream';
 import { strictAssert } from '../../util/assert';
 import type {
   WebAPIType,
@@ -66,6 +67,18 @@ export class BackupAPI {
     });
   }
 
+  public async download(): Promise<Readable> {
+    const { cdn, backupDir, backupName } = await this.getInfo();
+    const { headers } = await this.credentials.getCDNReadCredentials(cdn);
+
+    return this.server.getBackupStream({
+      cdn,
+      backupDir,
+      backupName,
+      headers,
+    });
+  }
+
   public async getMediaUploadForm(): Promise<AttachmentUploadFormResponseType> {
     return this.server.getBackupMediaUploadForm(
       await this.credentials.getHeadersForToday()

ts/services/backups/index.ts

@@ -129,6 +129,21 @@ export class BackupsService {
     return backupsService.importBackup(() => createReadStream(backupFile));
   }
 
+  public async download(): Promise<void> {
+    const path = window.Signal.Migrations.getAbsoluteTempPath(
+      randomBytes(32).toString('hex')
+    );
+
+    const stream = await this.api.download();
+    await pipeline(stream, createWriteStream(path));
+
+    try {
+      await this.importFromDisk(path);
+    } finally {
+      await unlink(path);
+    }
+  }
+
   public async importBackup(createBackupStream: () => Readable): Promise<void> {
     strictAssert(!this.isRunning, 'BackupService is already running');
 
@@ -281,7 +296,7 @@ export class BackupsService {
       await this.api.refresh();
       log.info('Backup: refreshed');
     } catch (error) {
-      log.error('Backup: periodic refresh kufailed', Errors.toLogFormat(error));
+      log.error('Backup: periodic refresh failed', Errors.toLogFormat(error));
     }
   }
 }

ts/textsecure/WebAPI.ts

@@ -1147,8 +1147,15 @@ export type GetBackupCDNCredentialsResponseType = z.infer<
   typeof getBackupCDNCredentialsResponseSchema
 >;
 
+export type GetBackupStreamOptionsType = Readonly<{
+  cdn: number;
+  backupDir: string;
+  backupName: string;
+  headers: Record<string, string>;
+}>;
+
 export const getBackupInfoResponseSchema = z.object({
-  cdn: z.number(),
+  cdn: z.literal(3),
   backupDir: z.string(),
   mediaDir: z.string(),
   backupName: z.string(),
@@ -1380,6 +1387,7 @@ export type WebAPIType = {
   getBackupInfo: (
     headers: BackupPresentationHeadersType
   ) => Promise<GetBackupInfoResponseType>;
+  getBackupStream: (options: GetBackupStreamOptionsType) => Promise<Readable>;
   getBackupUploadForm: (
     headers: BackupPresentationHeadersType
   ) => Promise<AttachmentUploadFormResponseType>;
@@ -1707,6 +1715,7 @@ export function initialize({
       getBackupCredentials,
       getBackupCDNCredentials,
       getBackupInfo,
+      getBackupStream,
       getBackupMediaUploadForm,
       getBackupUploadForm,
       getBadgeImageFile,
@@ -2764,6 +2773,20 @@ export function initialize({
       return getBackupInfoResponseSchema.parse(res);
     }
 
+    async function getBackupStream({
+      headers,
+      cdn,
+      backupDir,
+      backupName,
+    }: GetBackupStreamOptionsType): Promise<Readable> {
+      return _getAttachment({
+        cdnPath: `/backups/${encodeURIComponent(backupDir)}/${encodeURIComponent(backupName)}`,
+        cdnNumber: cdn,
+        redactor: _createRedactor(backupDir, backupName),
+        headers,
+      });
+    }
+
     async function getBackupMediaUploadForm(
       headers: BackupPresentationHeadersType
     ) {

ts/util/isBackupEnabled.ts

@@ -2,7 +2,15 @@
 // SPDX-License-Identifier: AGPL-3.0-only
 
 import * as RemoteConfig from '../RemoteConfig';
+import { Environment, getEnvironment } from '../environment';
+import { isStaging } from './version';
 
 export function isBackupEnabled(): boolean {
+  if (getEnvironment() === Environment.Staging) {
+    return true;
+  }
+  if (isStaging(window.getVersion())) {
+    return true;
+  }
   return Boolean(RemoteConfig.isEnabled('desktop.backup.credentialFetch'));
 }