From 7dfeb381295bc38bafbcd815867176ad25d07148 Mon Sep 17 00:00:00 2001
From: Fedor Indutny <79877362+indutny-signal@users.noreply.github.com>
Date: Fri, 10 Oct 2025 12:44:42 -0700
Subject: [PATCH] Use mp4san

---
 ts/test-electron/backup/integration_test.ts   |  2 +-
 .../backups => }/util/MemoryStream.ts         |  5 +--
 ts/util/handleVideoAttachment.ts              | 44 +++++++++++++++++--
 ts/util/processAttachment.ts                  |  2 +-
 4 files changed, 44 insertions(+), 9 deletions(-)
 rename ts/{services/backups => }/util/MemoryStream.ts (74%)

diff --git a/ts/test-electron/backup/integration_test.ts b/ts/test-electron/backup/integration_test.ts
index d2d5eccca4..9bcfb8555f 100644
--- a/ts/test-electron/backup/integration_test.ts
+++ b/ts/test-electron/backup/integration_test.ts
@@ -15,8 +15,8 @@ import { assert } from 'chai';
 import { clearData } from './helpers.js';
 import { loadAllAndReinitializeRedux } from '../../services/allLoaders.js';
 import { backupsService, BackupType } from '../../services/backups/index.js';
-import { MemoryStream } from '../../services/backups/util/MemoryStream.js';
 import { initialize as initializeExpiringMessageService } from '../../services/expiringMessagesDeletion.js';
+import { MemoryStream } from '../../util/MemoryStream.js';
 
 const { BACKUP_INTEGRATION_DIR } = process.env;
 
diff --git a/ts/services/backups/util/MemoryStream.ts b/ts/util/MemoryStream.ts
similarity index 74%
rename from ts/services/backups/util/MemoryStream.ts
rename to ts/util/MemoryStream.ts
index 260dbe788d..a61f3558fb 100644
--- a/ts/services/backups/util/MemoryStream.ts
+++ b/ts/util/MemoryStream.ts
@@ -1,17 +1,16 @@
 // Copyright 2025 Signal Messenger, LLC
 // SPDX-License-Identifier: AGPL-3.0-only
 
-import { type Buffer } from 'node:buffer';
 import { InputStream } from '@signalapp/libsignal-client/dist/io.js';
 
 export class MemoryStream extends InputStream {
   #offset = 0;
 
-  constructor(private readonly buffer: Buffer) {
+  constructor(private readonly buffer: Uint8Array) {
     super();
   }
 
-  public override async read(amount: number): Promise<Buffer> {
+  public override async read(amount: number): Promise<Uint8Array> {
     const result = this.buffer.subarray(this.#offset, this.#offset + amount);
     this.#offset += amount;
     return result;
diff --git a/ts/util/handleVideoAttachment.ts b/ts/util/handleVideoAttachment.ts
index ce79f5c9e9..41c84ef40f 100644
--- a/ts/util/handleVideoAttachment.ts
+++ b/ts/util/handleVideoAttachment.ts
@@ -2,23 +2,59 @@
 // SPDX-License-Identifier: AGPL-3.0-only
 
 import { blobToArrayBuffer } from 'blob-util';
+import { sanitize } from '@signalapp/libsignal-client/dist/Mp4Sanitizer.js';
 import { v4 as generateUuid } from 'uuid';
 
 import { makeVideoScreenshot } from '../types/VisualAttachment.js';
 import { IMAGE_PNG, stringToMIMEType } from '../types/MIME.js';
+import { toLogFormat } from '../types/errors.js';
 import type { InMemoryAttachmentDraftType } from '../types/Attachment.js';
+import { createLogger } from '../logging/log.js';
+import { MemoryStream } from './MemoryStream.js';
 import { fileToBytes } from './fileToBytes.js';
 
+const log = createLogger('handleVideoAttachment');
+
 export async function handleVideoAttachment(
   file: File,
-  options?: { generateScreenshot: boolean; flags: number | null }
+  options: {
+    generateScreenshot: boolean;
+    flags: number | null;
+  }
 ): Promise<InMemoryAttachmentDraftType> {
   const objectUrl = URL.createObjectURL(file);
   if (!objectUrl) {
     throw new Error('Failed to create object url for video!');
   }
   try {
-    const data = await fileToBytes(file);
+    let data = await fileToBytes(file);
+
+    if (file.type === 'video/mp4') {
+      try {
+        const result = await sanitize(
+          new MemoryStream(data),
+          BigInt(data.byteLength)
+        );
+        const metadata = result.getMetadata();
+
+        // If there is no metadata - mp4 is already in the fast state!
+        if (metadata != null) {
+          const dataLen = Number(result.getDataLen());
+          const dataOffset = Number(result.getDataOffset());
+          const sanitized = new Uint8Array(dataLen + metadata.byteLength);
+          sanitized.set(metadata, 0);
+          sanitized.set(
+            data.subarray(dataOffset, dataOffset + dataLen),
+            metadata.byteLength
+          );
+
+          data = sanitized;
+        }
+      } catch (error) {
+        log.warn(`Failed to mp4san video ${toLogFormat(error)}`);
+      }
+    }
+
     const attachment: InMemoryAttachmentDraftType = {
       contentType: stringToMIMEType(file.type),
       clientUuid: generateUuid(),
@@ -29,7 +65,7 @@ export async function handleVideoAttachment(
       size: data.byteLength,
     };
 
-    if (options?.generateScreenshot) {
+    if (options.generateScreenshot) {
       const screenshotContentType = IMAGE_PNG;
 
       const { blob: screenshotBlob, duration } = await makeVideoScreenshot({
@@ -43,7 +79,7 @@ export async function handleVideoAttachment(
       attachment.screenshotContentType = screenshotContentType;
     }
 
-    if (options?.flags != null) {
+    if (options.flags != null) {
       attachment.flags = options.flags;
     }
 
diff --git a/ts/util/processAttachment.ts b/ts/util/processAttachment.ts
index 8ec276a3f6..ec9690def3 100644
--- a/ts/util/processAttachment.ts
+++ b/ts/util/processAttachment.ts
@@ -28,7 +28,7 @@ const log = createLogger('processAttachment');
 
 export async function processAttachment(
   file: File,
-  options?: { generateScreenshot: boolean; flags: number | null }
+  options: { generateScreenshot: boolean; flags: number | null }
 ): Promise<InMemoryAttachmentDraftType | void> {
   const fileType = stringToMIMEType(file.type);