m->d support encrypted files

m2d/actions/send-event.js

@@ -1,6 +1,9 @@
 // @ts-check
 
 const assert = require("assert").strict
+const crypto = require("crypto")
+const {pipeline} = require("stream")
+const {promisify} = require("util")
 const Ty = require("../../types")
 const DiscordTypes = require("discord-api-types/v10")
 const passthrough = require("../../passthrough")
@@ -14,16 +17,29 @@ const eventToMessage = sync.require("../converters/event-to-message")
 const api = sync.require("../../matrix/api")
 
 /**
- * @param {DiscordTypes.RESTPostAPIWebhookWithTokenJSONBody & {pendingFiles?: {name: string, url: string}[]}} message
+ * @param {DiscordTypes.RESTPostAPIWebhookWithTokenJSONBody & {pendingFiles?: ({name: string, url: string} | {name: string, url: string, key: string, iv: string})[]}} message
  * @returns {Promise<DiscordTypes.RESTPostAPIWebhookWithTokenJSONBody & {files?: {name: string, file: Buffer}[]}>}
  */
 async function resolvePendingFiles(message) {
 	if (!message.pendingFiles) return message
 	const files = await Promise.all(message.pendingFiles.map(async p => {
-		const file = await fetch(p.url).then(res => res.arrayBuffer()).then(x => Buffer.from(x))
+		let fileBuffer
+		if ("key" in p) {
+			// Encrypted
+			const d = crypto.createDecipheriv("aes-256-ctr", Buffer.from(p.key, "base64url"), Buffer.from(p.iv, "base64url"))
+			fileBuffer = await fetch(p.url).then(res => res.arrayBuffer()).then(x => {
+				return Buffer.concat([
+					d.update(Buffer.from(x)),
+					d.final()
+				])
+			})
+		} else {
+			// Unencrypted
+			fileBuffer = await fetch(p.url).then(res => res.arrayBuffer()).then(x => Buffer.from(x))
+		}
 		return {
 			name: p.name,
-			file
+			file: fileBuffer // TODO: Once SnowTransfer supports ReadableStreams for attachment uploads, pass in those instead of Buffers
 		}
 	}))
 	const newMessage = {
@@ -34,7 +50,7 @@ async function resolvePendingFiles(message) {
 	return newMessage
 }
 
-/** @param {Ty.Event.M_Outer_M_Room_Message | Ty.Event.M_Outer_M_Room_Message_File | Ty.Event.M_Outer_M_Sticker} event */
+/** @param {Ty.Event.Outer_M_Room_Message | Ty.Event.Outer_M_Room_Message_File | Ty.Event.Outer_M_Sticker} event */
 async function sendEvent(event) {
 	// TODO: we just assume the bridge has already been created, is that really ok?
 	const row = db.prepare("SELECT channel_id, thread_parent FROM channel_room WHERE room_id = ?").get(event.room_id)

m2d/converters/event-to-message.js

@@ -125,7 +125,7 @@ async function getMemberFromCacheOrHomeserver(roomID, mxid, api) {
 }
 
 /**
- * @param {Ty.Event.M_Outer_M_Room_Message | Ty.Event.M_Outer_M_Room_Message_File | Ty.Event.M_Outer_M_Sticker} event
+ * @param {Ty.Event.Outer_M_Room_Message | Ty.Event.Outer_M_Room_Message_File | Ty.Event.Outer_M_Sticker | Ty.Event.Outer_M_Room_Message_Encrypted_File} event
  * @param {import("discord-api-types/v10").APIGuild} guild
  * @param {{api: import("../../matrix/api")}} di simple-as-nails dependency injection for the matrix API
  */
@@ -148,7 +148,7 @@ async function eventToMessage(event, guild, di) {
 
 	let content = event.content.body // ultimate fallback
 	const attachments = []
-	/** @type {{name: string, url: string}[]} */
+	/** @type {({name: string, url: string} | {name: string, url: string, key: string, iv: string})[]} */
 	const pendingFiles = []
 
 	// Convert content depending on what the message is
@@ -281,10 +281,20 @@ async function eventToMessage(event, guild, di) {
 	} else if (event.type === "m.room.message" && (event.content.msgtype === "m.file" || event.content.msgtype === "m.video" || event.content.msgtype === "m.audio" || event.content.msgtype === "m.image")) {
 		content = ""
 		const filename = event.content.body
-		const url = utils.getPublicUrlForMxc(event.content.url)
-		assert(url)
-		attachments.push({id: "0", filename})
-		pendingFiles.push({name: filename, url})
+		if ("url" in event.content) {
+			// Unencrypted
+			const url = utils.getPublicUrlForMxc(event.content.url)
+			assert(url)
+			attachments.push({id: "0", filename})
+			pendingFiles.push({name: filename, url})
+		} else {
+			// Encrypted
+			const url = utils.getPublicUrlForMxc(event.content.file.url)
+			assert(url)
+			assert.equal(event.content.file.key.alg, "A256CTR")
+			attachments.push({id: "0", filename})
+			pendingFiles.push({name: filename, url, key: event.content.file.key.k, iv: event.content.file.iv})
+		}
 	} else if (event.type === "m.sticker") {
 		content = ""
 		let filename = event.content.body

m2d/converters/event-to-message.test.js

@@ -1176,6 +1176,60 @@ test("event2message: image attachments work", async t => {
 	)
 })
 
+test("event2message: encrypted image attachments work", async t => {
+	t.deepEqual(
+		await eventToMessage({
+			type: "m.room.message",
+			sender: "@cadence:cadence.moe",
+			content: {
+				info: {
+					mimetype: "image/png",
+					size: 105691,
+					w: 1192,
+					h: 309,
+					"xyz.amorgan.blurhash": "U17USN~q9FtQ-;Rjxuj[9FIUoMM|-=WB9Ft7"
+				},
+				msgtype: "m.image",
+				body: "image.png",
+				file: {
+					v: "v2",
+					key: {
+						alg: "A256CTR",
+						ext: true,
+						k: "QTo-oMPnN1Rbc7vBFg9WXMgoctscdyxdFEIYm8NYceo",
+						key_ops: ["encrypt", "decrypt"],
+						kty: "oct"
+					},
+					iv: "Va9SHZpIn5kAAAAAAAAAAA",
+					hashes: {
+						sha256: "OUZqZFBcANFt42iAKET9YXfWMCdT0BX7QO0Eyk9q4Js"
+					},
+					url: "mxc://heyquark.com/LOGkUTlVFrqfiExlGZNgCJJX",
+					mimetype: "image/png"
+				}
+			},
+			event_id: "$JNhONhXO-5jrztZz8b7mbTMJasbU78TwQr4tog-3Mnk",
+			room_id: "!PnyBKvUBOhjuCucEfk:cadence.moe"
+		}),
+		{
+			messagesToDelete: [],
+			messagesToEdit: [],
+			messagesToSend: [{
+				username: "cadence [they]",
+				content: "",
+				avatar_url: "https://matrix.cadence.moe/_matrix/media/r0/download/cadence.moe/azCAhThKTojXSZJRoWwZmhvU",
+				attachments: [{id: "0", filename: "image.png"}],
+				pendingFiles: [{
+					name: "image.png",
+					url: "https://matrix.cadence.moe/_matrix/media/r0/download/heyquark.com/LOGkUTlVFrqfiExlGZNgCJJX",
+					key: "QTo-oMPnN1Rbc7vBFg9WXMgoctscdyxdFEIYm8NYceo",
+					iv: "Va9SHZpIn5kAAAAAAAAAAA"
+				}]
+			}]
+		}
+	)
+})
+
 test("event2message: stickers work", async t => {
 	t.deepEqual(
 		await eventToMessage({

m2d/event-dispatcher.js

@@ -54,7 +54,7 @@ function guard(type, fn) {
 
 sync.addTemporaryListener(as, "type:m.room.message", guard("m.room.message",
 /**
- * @param {Ty.Event.M_Outer_M_Room_Message | Ty.Event.M_Outer_M_Room_Message_File} event it is a m.room.message because that's what this listener is filtering for
+ * @param {Ty.Event.Outer_M_Room_Message | Ty.Event.Outer_M_Room_Message_File} event it is a m.room.message because that's what this listener is filtering for
  */
 async event => {
 	if (utils.eventSenderIsFromDiscord(event.sender)) return
@@ -63,7 +63,7 @@ async event => {
 
 sync.addTemporaryListener(as, "type:m.sticker", guard("m.sticker",
 /**
- * @param {Ty.Event.M_Outer_M_Sticker} event it is a m.sticker because that's what this listener is filtering for
+ * @param {Ty.Event.Outer_M_Sticker} event it is a m.sticker because that's what this listener is filtering for
  */
 async event => {
 	if (utils.eventSenderIsFromDiscord(event.sender)) return