Files
element-web/src/utils/DecryptFile.ts
T
David Langley 69ee8fd96a Change License: AGPL + Element Commercial (#28856)
* Add commercial licence and update config files

* Update license in headers

* Revert "Update license in headers"

This reverts commit 7ed7949485e88889a9ffc8075a9df1f8e936777e.

* Update only spdx id

* Remove LicenseRef- from package.json

LicenseRef- no longer allowed in npm v3 package.json
This fixes the warning in the logs and failing build check.
2025-01-06 11:18:54 +00:00

75 lines
2.7 KiB
TypeScript

/*
Copyright 2024 New Vector Ltd.
Copyright 2016-2018 , 2021 The Matrix.org Foundation C.I.C.
SPDX-License-Identifier: AGPL-3.0-only OR GPL-3.0-only OR LicenseRef-Element-Commercial
Please see LICENSE files in the repository root for full details.
*/
// Pull in the encryption lib so that we can decrypt attachments.
import encrypt from "matrix-encrypt-attachment";
import { parseErrorResponse } from "matrix-js-sdk/src/matrix";
import { EncryptedFile, MediaEventInfo } from "matrix-js-sdk/src/types";
import { mediaFromContent } from "../customisations/Media";
import { getBlobSafeMimeType } from "./blobs";
export class DownloadError extends Error {
public constructor(e: Error) {
super(e.message);
this.name = "DownloadError";
this.stack = e.stack;
}
}
export class DecryptError extends Error {
public constructor(e: Error) {
super(e.message);
this.name = "DecryptError";
this.stack = e.stack;
}
}
/**
* Decrypt a file attached to a matrix event.
* @param {EncryptedFile} file The encrypted file information taken from the matrix event.
* This passed to [link]{@link https://github.com/matrix-org/matrix-encrypt-attachment}
* as the encryption info object, so will also have the those keys in addition to
* the keys below.
* @param {MediaEventInfo} info The info parameter taken from the matrix event.
* @returns {Promise<Blob>} Resolves to a Blob of the file.
*/
export async function decryptFile(file?: EncryptedFile, info?: MediaEventInfo): Promise<Blob> {
// throws if file is falsy
const media = mediaFromContent({ file });
let responseData: ArrayBuffer;
try {
// Download the encrypted file as an array buffer.
const response = await media.downloadSource();
if (!response.ok) {
throw parseErrorResponse(response, await response.text());
}
responseData = await response.arrayBuffer();
} catch (e) {
throw new DownloadError(e as Error);
}
try {
// Decrypt the array buffer using the information taken from the event content.
const dataArray = await encrypt.decryptAttachment(responseData, file!);
// Turn the array into a Blob and give it the correct MIME-type.
// IMPORTANT: we must not allow scriptable mime-types into Blobs otherwise
// they introduce XSS attacks if the Blob URI is viewed directly in the
// browser (e.g. by copying the URI into a new tab or window.)
// See warning at top of file.
let mimetype = info?.mimetype ? info.mimetype.split(";")[0].trim() : "";
mimetype = getBlobSafeMimeType(mimetype);
return new Blob([dataArray], { type: mimetype });
} catch (e) {
throw new DecryptError(e as Error);
}
}