Move to websocket for requests to signal server

ts/textsecure/downloadAttachment.ts

@@ -0,0 +1,61 @@
+// Copyright 2020-2021 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import { isNumber, omit } from 'lodash';
+
+import { strictAssert } from '../util/assert';
+import { dropNull } from '../util/dropNull';
+import { DownloadedAttachmentType } from '../types/Attachment';
+import * as MIME from '../types/MIME';
+import * as Bytes from '../Bytes';
+import { typedArrayToArrayBuffer } from '../Crypto';
+
+import Crypto from './Crypto';
+import { ProcessedAttachment } from './Types.d';
+import type { WebAPIType } from './WebAPI';
+
+export async function downloadAttachment(
+  server: WebAPIType,
+  attachment: ProcessedAttachment
+): Promise<DownloadedAttachmentType> {
+  const cdnId = attachment.cdnId || attachment.cdnKey;
+  const { cdnNumber } = attachment;
+
+  if (!cdnId) {
+    throw new Error('downloadAttachment: Attachment was missing cdnId!');
+  }
+
+  strictAssert(cdnId, 'attachment without cdnId');
+  const encrypted = await server.getAttachment(cdnId, dropNull(cdnNumber));
+  const { key, digest, size, contentType } = attachment;
+
+  if (!digest) {
+    throw new Error('Failure: Ask sender to update Signal and resend.');
+  }
+
+  strictAssert(key, 'attachment has no key');
+  strictAssert(digest, 'attachment has no digest');
+
+  const paddedData = await Crypto.decryptAttachment(
+    encrypted,
+    typedArrayToArrayBuffer(Bytes.fromBase64(key)),
+    typedArrayToArrayBuffer(Bytes.fromBase64(digest))
+  );
+
+  if (!isNumber(size)) {
+    throw new Error(
+      `downloadAttachment: Size was not provided, actual size was ${paddedData.byteLength}`
+    );
+  }
+
+  const data = window.Signal.Crypto.getFirstBytes(paddedData, size);
+
+  return {
+    ...omit(attachment, 'digest', 'key'),
+
+    contentType: contentType
+      ? MIME.fromString(contentType)
+      : MIME.APPLICATION_OCTET_STREAM,
+    data,
+  };
+}