82 lines
3.1 KiB
TypeScript
82 lines
3.1 KiB
TypeScript
/*
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Copyright 2016, 2018, 2021 The Matrix.org Foundation C.I.C.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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// Pull in the encryption lib so that we can decrypt attachments.
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import encrypt from "matrix-encrypt-attachment";
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import { parseErrorResponse } from "matrix-js-sdk/src/matrix";
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import { EncryptedFile, MediaEventInfo } from "matrix-js-sdk/src/types";
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import { mediaFromContent } from "../customisations/Media";
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import { getBlobSafeMimeType } from "./blobs";
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export class DownloadError extends Error {
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public constructor(e: Error) {
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super(e.message);
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this.name = "DownloadError";
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this.stack = e.stack;
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}
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}
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export class DecryptError extends Error {
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public constructor(e: Error) {
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super(e.message);
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this.name = "DecryptError";
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this.stack = e.stack;
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}
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}
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/**
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* Decrypt a file attached to a matrix event.
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* @param {EncryptedFile} file The encrypted file information taken from the matrix event.
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* This passed to [link]{@link https://github.com/matrix-org/matrix-encrypt-attachment}
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* as the encryption info object, so will also have the those keys in addition to
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* the keys below.
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* @param {MediaEventInfo} info The info parameter taken from the matrix event.
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* @returns {Promise<Blob>} Resolves to a Blob of the file.
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*/
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export async function decryptFile(file?: EncryptedFile, info?: MediaEventInfo): Promise<Blob> {
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// throws if file is falsy
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const media = mediaFromContent({ file });
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let responseData: ArrayBuffer;
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try {
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// Download the encrypted file as an array buffer.
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const response = await media.downloadSource();
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if (!response.ok) {
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throw parseErrorResponse(response, await response.text());
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}
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responseData = await response.arrayBuffer();
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} catch (e) {
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throw new DownloadError(e as Error);
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}
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try {
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// Decrypt the array buffer using the information taken from the event content.
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const dataArray = await encrypt.decryptAttachment(responseData, file!);
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// Turn the array into a Blob and give it the correct MIME-type.
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// IMPORTANT: we must not allow scriptable mime-types into Blobs otherwise
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// they introduce XSS attacks if the Blob URI is viewed directly in the
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// browser (e.g. by copying the URI into a new tab or window.)
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// See warning at top of file.
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let mimetype = info?.mimetype ? info.mimetype.split(";")[0].trim() : "";
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mimetype = getBlobSafeMimeType(mimetype);
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return new Blob([dataArray], { type: mimetype });
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} catch (e) {
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throw new DecryptError(e as Error);
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}
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}
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