Add "please try invite" message when joinRoom in /api/link-space fails

When using self-service mode and trying to link with a remote matrix
room (room not in the same HS as the bridge user), then we need to add
the "via" HSs to join the room with, or else it fails.

We get it from the "m.space.child" in the "children_state" of the space
hierarchy.

It seems like the "via" information can also be stored in the
"m.space.parent" in the states of the room, but hopefully this shouldn't
be needed in sane implementations

src/d2m/converters/edit-to-changes.js

@@ -22,6 +22,10 @@ function eventCanBeEdited(ev) {
 	return true
 }
 
+function eventIsText(ev) {
+	return ev.old.event_type === "m.room.message" && (ev.old.event_subtype === "m.text" || ev.old.event_subtype === "m.notice")
+}
+
 /**
  * @param {import("discord-api-types/v10").GatewayMessageCreateDispatchData} message
  * @param {import("discord-api-types/v10").APIGuild} guild
@@ -121,6 +125,20 @@ async function editToChanges(message, guild, api) {
 	unchangedEvents.push(...eventsToReplace.filter(ev => !eventCanBeEdited(ev))) // Move them from eventsToRedact to unchangedEvents.
 	eventsToReplace = eventsToReplace.filter(eventCanBeEdited)
 
+	// Now, everything in eventsToReplace has the potential to have changed, but did it actually?
+	// (Example: if a URL preview was generated or updated, the message text won't have changed.)
+	// Only way to detect this is by text content. So we'll remove text events from eventsToReplace that have the same new text as text currently in the event.
+	for (let i = eventsToReplace.length; i--;) { // move backwards through array
+		const event = eventsToReplace[i]
+		if (!eventIsText(event)) continue // not text, can't analyse
+		const oldEvent = await api.getEvent(roomID, eventsToReplace[i].old.event_id)
+		const oldEventBodyWithoutQuotedReply = oldEvent.content.body?.replace(/^(>.*\n)*\n*/sm, "")
+		if (oldEventBodyWithoutQuotedReply !== event.newInnerContent.body) continue // event changed, must replace it
+		// Move it from eventsToRedact to unchangedEvents.
+		unchangedEvents.push(...eventsToReplace.filter(ev => ev.old.event_id === event.old.event_id))
+		eventsToReplace = eventsToReplace.filter(ev => ev.old.event_id !== event.old.event_id)
+	}
+
 	// We want to maintain exactly one part = 0 and one reaction_part = 0 database row at all times.
 	// This would be disrupted if existing events that are (reaction_)part = 0 will be redacted.
 	// If that is the case, pick a different existing or newly sent event to be (reaction_)part = 0.
@@ -193,4 +211,3 @@ function makeReplacementEventContent(oldID, newFallbackContent, newInnerContent)
 }
 
 module.exports.editToChanges = editToChanges
-module.exports.makeReplacementEventContent = makeReplacementEventContent

src/d2m/converters/edit-to-changes.test.js

@@ -4,7 +4,14 @@ const data = require("../../../test/data")
 const Ty = require("../../types")
 
 test("edit2changes: edit by webhook", async t => {
-	const {senderMxid, eventsToRedact, eventsToReplace, eventsToSend, promotions} = await editToChanges(data.message_update.edit_by_webhook, data.guild.general, {})
+	let called = 0
+	const {senderMxid, eventsToRedact, eventsToReplace, eventsToSend, promotions} = await editToChanges(data.message_update.edit_by_webhook, data.guild.general, {
+		getEvent(roomID, eventID) {
+			called++
+			t.equal(eventID, "$zXSlyI78DQqQwwfPUSzZ1b-nXzbUrCDljJgnGDdoI10")
+			return {content: {body: "dummy"}}
+		}
+	})
 	t.deepEqual(eventsToRedact, [])
 	t.deepEqual(eventsToSend, [])
 	t.deepEqual(eventsToReplace, [{
@@ -28,10 +35,15 @@ test("edit2changes: edit by webhook", async t => {
 	}])
 	t.equal(senderMxid, null)
 	t.deepEqual(promotions, [])
+	t.equal(called, 1)
 })
 
 test("edit2changes: bot response", async t => {
 	const {senderMxid, eventsToRedact, eventsToReplace, eventsToSend, promotions} = await editToChanges(data.message_update.bot_response, data.guild.general, {
+		getEvent(roomID, eventID) {
+			t.equal(eventID, "$fdD9OZ55xg3EAsfvLZza5tMhtjUO91Wg3Otuo96TplY")
+			return {content: {body: "dummy"}}
+		},
 		async getJoinedMembers(roomID) {
 			t.equal(roomID, "!hYnGGlPHlbujVVfktC:cadence.moe")
 			return new Promise(resolve => {
@@ -123,7 +135,14 @@ test("edit2changes: add caption back to that image (due to it having a reaction,
 })
 
 test("edit2changes: stickers and attachments are not changed, only the content can be edited", async t => {
-	const {eventsToRedact, eventsToReplace, eventsToSend} = await editToChanges(data.message_update.edited_content_with_sticker_and_attachments, data.guild.general, {})
+	let called = 0
+	const {eventsToRedact, eventsToReplace, eventsToSend} = await editToChanges(data.message_update.edited_content_with_sticker_and_attachments, data.guild.general, {
+		getEvent(roomID, eventID) {
+			called++
+			t.equal(eventID, "$lnAF9IosAECTnlv9p2e18FG8rHn-JgYKHEHIh5qdFv4")
+			return {content: {body: "dummy"}}
+		}
+	})
 	t.deepEqual(eventsToRedact, [])
 	t.deepEqual(eventsToSend, [])
 	t.deepEqual(eventsToReplace, [{
@@ -145,10 +164,16 @@ test("edit2changes: stickers and attachments are not changed, only the content c
 			}
 		}
 	}])
+	t.equal(called, 1)
 })
 
 test("edit2changes: edit of reply to skull webp attachment with content", async t => {
-	const {eventsToRedact, eventsToReplace, eventsToSend} = await editToChanges(data.message_update.edit_of_reply_to_skull_webp_attachment_with_content, data.guild.general, {})
+	const {eventsToRedact, eventsToReplace, eventsToSend} = await editToChanges(data.message_update.edit_of_reply_to_skull_webp_attachment_with_content, data.guild.general, {
+		getEvent(roomID, eventID) {
+			t.equal(eventID, "$vgTKOR5ZTYNMKaS7XvgEIDaOWZtVCEyzLLi5Pc5Gz4M")
+			return {content: {body: "dummy"}}
+		}
+	})
 	t.deepEqual(eventsToRedact, [])
 	t.deepEqual(eventsToSend, [])
 	t.deepEqual(eventsToReplace, [{
@@ -177,7 +202,12 @@ test("edit2changes: edit of reply to skull webp attachment with content", async
 })
 
 test("edit2changes: edits the text event when multiple rows have part = 0 (should never happen in real life, but make sure the safety net works)", async t => {
-	const {eventsToRedact, eventsToReplace, eventsToSend} = await editToChanges(data.message_update.edited_content_with_sticker_and_attachments_but_all_parts_equal_0, data.guild.general, {})
+	const {eventsToRedact, eventsToReplace, eventsToSend} = await editToChanges(data.message_update.edited_content_with_sticker_and_attachments_but_all_parts_equal_0, data.guild.general, {
+		getEvent(roomID, eventID) {
+			t.equal(eventID, "$lnAF9IosAECTnlv9p2e18FG8rHn-JgYKHEHIh5qd999")
+			return {content: {body: "dummy"}}
+		}
+	})
 	t.deepEqual(eventsToRedact, [])
 	t.deepEqual(eventsToSend, [])
 	t.deepEqual(eventsToReplace, [{
@@ -202,7 +232,12 @@ test("edit2changes: edits the text event when multiple rows have part = 0 (shoul
 })
 
 test("edit2changes: promotes the text event when multiple rows have part = 1 (should never happen in real life, but make sure the safety net works)", async t => {
-	const {eventsToRedact, eventsToReplace, eventsToSend, promotions} = await editToChanges(data.message_update.edited_content_with_sticker_and_attachments_but_all_parts_equal_1, data.guild.general, {})
+	const {eventsToRedact, eventsToReplace, eventsToSend, promotions} = await editToChanges(data.message_update.edited_content_with_sticker_and_attachments_but_all_parts_equal_1, data.guild.general, {
+		getEvent(roomID, eventID) {
+			t.equal(eventID, "$lnAF9IosAECTnlv9p2e18FG8rHn-JgYKHEHIh5qd111")
+			return {content: {body: "dummy"}}
+		}
+	})
 	t.deepEqual(eventsToRedact, [])
 	t.deepEqual(eventsToSend, [])
 	t.deepEqual(eventsToReplace, [{
@@ -279,32 +314,31 @@ test("edit2changes: generated embed", async t => {
 })
 
 test("edit2changes: generated embed on a reply", async t => {
-	const {senderMxid, eventsToRedact, eventsToReplace, eventsToSend, promotions} = await editToChanges(data.message_update.embed_generated_on_reply, data.guild.general, {})
-	t.deepEqual(eventsToRedact, [])
-	t.deepEqual(eventsToReplace, [{
-		oldID: "$UTqiL3Zj3FC4qldxRLggN1fhygpKl8sZ7XGY5f9MNbF",
-		newContent: {
-			$type: "m.room.message",
+	let called = 0
+	const {senderMxid, eventsToRedact, eventsToReplace, eventsToSend, promotions} = await editToChanges(data.message_update.embed_generated_on_reply, data.guild.general, {
+		getEvent(roomID, eventID) {
+			called++
+			t.equal(eventID, "$UTqiL3Zj3FC4qldxRLggN1fhygpKl8sZ7XGY5f9MNbF")
+			return {
+				type: "m.room.message",
+				content: {
 					// Unfortunately the edited message doesn't include the message_reference field. Fine. Whatever. It looks normal if you're using a good client.
 					body: "> a Discord user: [Replied-to message content wasn't provided by Discord]"
-				+ "\n\n* https://matrix.to/#/!BnKuBPCvyfOkhcUjEu:cadence.moe/$aLVZyiC3HlOu-prCSIaXlQl68I8leUdnPFiCwkgn6qM",
+						+ "\n\nhttps://matrix.to/#/!BnKuBPCvyfOkhcUjEu:cadence.moe/$aLVZyiC3HlOu-prCSIaXlQl68I8leUdnPFiCwkgn6qM",
 					format: "org.matrix.custom.html",
-			formatted_body: "<mx-reply><blockquote><a href=\"https://matrix.to/#/!BnKuBPCvyfOkhcUjEu:cadence.moe/$aLVZyiC3HlOu-prCSIaXlQl68I8leUdnPFiCwkgn6qM\">In reply to</a> a Discord user<br>[Replied-to message content wasn't provided by Discord]</blockquote></mx-reply>* <a href=\"https://matrix.to/#/!BnKuBPCvyfOkhcUjEu:cadence.moe/$aLVZyiC3HlOu-prCSIaXlQl68I8leUdnPFiCwkgn6qM\">https://matrix.to/#/!BnKuBPCvyfOkhcUjEu:cadence.moe/$aLVZyiC3HlOu-prCSIaXlQl68I8leUdnPFiCwkgn6qM</a>",
+					formatted_body: "<mx-reply><blockquote><a href=\"https://matrix.to/#/!BnKuBPCvyfOkhcUjEu:cadence.moe/$aLVZyiC3HlOu-prCSIaXlQl68I8leUdnPFiCwkgn6qM\">In reply to</a> a Discord user<br>[Replied-to message content wasn't provided by Discord]</blockquote></mx-reply><a href=\"https://matrix.to/#/!BnKuBPCvyfOkhcUjEu:cadence.moe/$aLVZyiC3HlOu-prCSIaXlQl68I8leUdnPFiCwkgn6qM\">https://matrix.to/#/!BnKuBPCvyfOkhcUjEu:cadence.moe/$aLVZyiC3HlOu-prCSIaXlQl68I8leUdnPFiCwkgn6qM</a>",
 					"m.mentions": {},
-			"m.new_content": {
-				body: "https://matrix.to/#/!BnKuBPCvyfOkhcUjEu:cadence.moe/$aLVZyiC3HlOu-prCSIaXlQl68I8leUdnPFiCwkgn6qM",
-				format: "org.matrix.custom.html",
-				formatted_body: "<a href=\"https://matrix.to/#/!BnKuBPCvyfOkhcUjEu:cadence.moe/$aLVZyiC3HlOu-prCSIaXlQl68I8leUdnPFiCwkgn6qM\">https://matrix.to/#/!BnKuBPCvyfOkhcUjEu:cadence.moe/$aLVZyiC3HlOu-prCSIaXlQl68I8leUdnPFiCwkgn6qM</a>",
-				"m.mentions": {},
-				msgtype: "m.text",
-			},
 					"m.relates_to": {
 						event_id: "$UTqiL3Zj3FC4qldxRLggN1fhygpKl8sZ7XGY5f9MNbF",
 						rel_type: "m.replace",
 					},
 					msgtype: "m.text",
-		},
-	}])
+				}
+			}
+		}
+	})
+	t.deepEqual(eventsToRedact, [])
+	t.deepEqual(eventsToReplace, [])
 	t.deepEqual(eventsToSend, [{
 		$type: "m.room.message",
 		msgtype: "m.notice",
@@ -324,4 +358,5 @@ test("edit2changes: generated embed on a reply", async t => {
 		"nextEvent": true,
 	}])
 	t.equal(senderMxid, "@_ooye_cadence:cadence.moe")
+	t.equal(called, 1)
 })

src/matrix/api.js

@@ -22,7 +22,11 @@ function path(p, mxid, otherParams = {}) {
 	const u = new URL(p, "http://localhost")
 	if (mxid) u.searchParams.set("user_id", mxid)
 	for (const entry of Object.entries(otherParams)) {
-		if (entry[1] != undefined) {
+		if (Array.isArray(entry[1])) {
+			for (const element of entry[1]) {
+				u.searchParams.append(entry[0], element)
+			}
+		} else if (entry[1] != undefined) {
 			u.searchParams.set(entry[0], entry[1])
 		}
 	}
@@ -62,11 +66,14 @@ async function createRoom(content) {
 }
 
 /**
+ * @param {string} roomIDOrAlias
+ * @param {string?} [mxid]
+ * @param {string[]?} [via]
  * @returns {Promise<string>} room ID
  */
-async function joinRoom(roomIDOrAlias, mxid) {
+async function joinRoom(roomIDOrAlias, mxid, via) {
 	/** @type {Ty.R.RoomJoined} */
-	const root = await mreq.mreq("POST", path(`/client/v3/join/${roomIDOrAlias}`, mxid), {})
+	const root = await mreq.mreq("POST", path(`/client/v3/join/${roomIDOrAlias}`, mxid, {via}), {})
 	return root.room_id
 }
 

src/matrix/api.test.js

@@ -24,3 +24,7 @@ test("api path: real world mxid", t => {
 test("api path: extras number works", t => {
 	t.equal(path(`/client/v3/rooms/!example/timestamp_to_event`, null, {ts: 1687324651120}), "/client/v3/rooms/!example/timestamp_to_event?ts=1687324651120")
 })
+
+test("api path: multiple via params", t => {
+	t.equal(path(`/client/v3/rooms/!example/join`, null, {via: ["cadence.moe", "matrix.org"], ts: 1687324651120}), "/client/v3/rooms/!example/join?via=cadence.moe&via=matrix.org&ts=1687324651120")
+})

src/types.d.ts

@@ -148,6 +148,14 @@ export namespace Event {
 		prev_content?: any
 	}
 
+	export type Outer_StrippedChildStateEvent = {
+		type: string
+		state_key: string
+		sender: string
+		origin_server_ts: number
+		content: any
+	}
+
 	export type M_Room_Message = {
 		msgtype: "m.text" | "m.emote"
 		body: string
@@ -344,7 +352,7 @@ export namespace R {
 	export type Hierarchy = {
 		avatar_url?: string
 		canonical_alias?: string
-		children_state: {}
+		children_state: Event.Outer_StrippedChildStateEvent[]
 		guest_can_join: boolean
 		join_rule?: string
 		name?: string

src/web/routes/link.js

@@ -12,6 +12,20 @@ const auth = sync.require("../auth")
 const mreq = sync.require("../../matrix/mreq")
 const {reg} = require("../../matrix/read-registration")
 
+/**
+ * @param {string} UserID
+ * @returns {string} the HS of the user, or "" if the user ID is malformed
+ */
+function getHSOfUser(user) {
+	domainStartIndex = user.indexOf(":");
+	if (domainStartIndex >= 1) {
+		return user.slice(domainStartIndex + 1)
+	}
+
+	return ""
+}
+
+
 /**
  * @param {H3Event} event
  * @returns {import("../../matrix/api")}
@@ -75,10 +89,16 @@ as.router.post("/api/link-space", defineEventHandler(async event => {
 	const existing = select("guild_space", "guild_id", {}, "WHERE guild_id = ? OR space_id = ?").get(guildID, spaceID)
 	if (existing) throw createError({status: 400, message: "Bad Request", data: `Guild ID ${guildID} or space ID ${spaceID} are already bridged and cannot be reused`})
 
+	const inviteSender = select("invite", "mxid", {mxid: session.data.mxid, room_id: spaceID}).pluck().get()
+	via = [ getHSOfUser(inviteSender) ]
+
 	// Check space exists and bridge is joined
 	try {
-		await api.joinRoom(parsedBody.space_id)
+		await api.joinRoom(parsedBody.space_id, null, via)
 	} catch (e) {
+		if (via.join("") == "") {
+			throw createError({status: 403, message: "Unable To Join", data: `Unable to join the requested Matrix space. Please invite the bridge to the space and try again. (Server said: ${e.errcode} - ${e.message})`})
+		}
 		throw createError({status: 403, message: e.errcode, data: `${e.errcode} - ${e.message}`})
 	}
 
@@ -134,19 +154,33 @@ as.router.post("/api/link", defineEventHandler(async event => {
 	if (row) throw createError({status: 400, message: "Bad Request", data: `Channel ID ${row.channel_id} or room ID ${parsedBody.matrix} are already bridged and cannot be reused`})
 
 	// Check room is part of the guild's space
-	let found = false
+	let foundRoom = false
+	/** @type {string[]?} */
+	let foundVia = null
 	for await (const room of api.generateFullHierarchy(spaceID)) {
+		// When finding a space during iteration, look at space's children state, because we need a `via` to join the room (when we find it later)
+		for (const state of room.children_state) {
+			if (state.type === "m.space.child" && state.state_key === parsedBody.matrix) {
+				foundVia = state.content.via
+			}
+		}
+
+		// When finding a room during iteration, see if it was the requested room (to confirm that the room is in the space)
 		if (room.room_id === parsedBody.matrix && !room.room_type) {
-			found = true
-			break
+			foundRoom = true
 		}
+
+		if (foundRoom && foundVia) break
 	}
-	if (!found) throw createError({status: 400, message: "Bad Request", data: "Matrix room needs to be part of the bridged space"})
+	if (!foundRoom) throw createError({status: 400, message: "Bad Request", data: "Matrix room needs to be part of the bridged space"})
 
 	// Check room exists and bridge is joined
 	try {
-		await api.joinRoom(parsedBody.matrix)
+		await api.joinRoom(parsedBody.matrix, null, foundVia)
 	} catch (e) {
+		if (!foundVia) {
+			throw createError({status: 403, message: "Unable To Join", data: `Unable to join the requested Matrix room. Please invite the bridge to the room and try again. (Server said: ${e.errcode} - ${e.message})`})
+		}
 		throw createError({status: 403, message: e.errcode, data: `${e.errcode} - ${e.message}`})
 	}
 

src/web/routes/link.test.js

@@ -360,7 +360,7 @@ test("web link room: check that room is part of space (not in hierarchy)", async
 	t.equal(called, 1)
 })
 
-test("web link room: check that bridge can join room", async t => {
+test("web link room: check that bridge can join room (notices lack of via and asks for invite instead)", async t => {
 	let called = 0
 	const [error] = await tryToCatch(() => router.test("post", "/api/link", {
 		sessionData: {
@@ -381,7 +381,55 @@ test("web link room: check that bridge can join room", async t => {
 				t.equal(spaceID, "!zTMspHVUBhFLLSdmnS:cadence.moe")
 				yield {
 					room_id: "!NDbIqNpJyPvfKRnNcr:cadence.moe",
-					children_state: {},
+					children_state: [],
+					guest_can_join: false,
+					num_joined_members: 2
+				}
+				/* c8 ignore next */
+			}
+		}
+	}))
+	t.equal(error.data, "Unable to join the requested Matrix room. Please invite the bridge to the room and try again. (Server said: M_FORBIDDEN - not allowed to join I guess)")
+	t.equal(called, 2)
+})
+
+test("web link room: check that bridge can join room (uses via for join attempt)", async t => {
+	let called = 0
+	const [error] = await tryToCatch(() => router.test("post", "/api/link", {
+		sessionData: {
+			managedGuilds: ["665289423482519565"]
+		},
+		body: {
+			discord: "665310973967597573",
+			matrix: "!NDbIqNpJyPvfKRnNcr:cadence.moe",
+			guild_id: "665289423482519565"
+		},
+		api: {
+			async joinRoom(roomID, _, via) {
+				called++
+				t.deepEqual(via, ["cadence.moe", "hashi.re"])
+				throw new MatrixServerError({errcode: "M_FORBIDDEN", error: "not allowed to join I guess"})
+			},
+			async *generateFullHierarchy(spaceID) {
+				called++
+				t.equal(spaceID, "!zTMspHVUBhFLLSdmnS:cadence.moe")
+				yield {
+					room_id: "!NDbIqNpJyPvfKRnNcr:cadence.moe",
+					children_state: [],
+					guest_can_join: false,
+					num_joined_members: 2
+				}
+				yield {
+					room_id: "!zTMspHVUBhFLLSdmnS:cadence.moe",
+					children_state: [{
+						type: "m.space.child",
+						state_key: "!NDbIqNpJyPvfKRnNcr:cadence.moe",
+						sender: "@elliu:hashi.re",
+						content: {
+							via: ["cadence.moe", "hashi.re"]
+						},
+						origin_server_ts: 0
+					}],
 					guest_can_join: false,
 					num_joined_members: 2
 				}
@@ -414,7 +462,7 @@ test("web link room: check that bridge has PL 100 in target room (event missing)
 				t.equal(spaceID, "!zTMspHVUBhFLLSdmnS:cadence.moe")
 				yield {
 					room_id: "!NDbIqNpJyPvfKRnNcr:cadence.moe",
-					children_state: {},
+					children_state: [],
 					guest_can_join: false,
 					num_joined_members: 2
 				}
@@ -454,7 +502,7 @@ test("web link room: check that bridge has PL 100 in target room (users default)
 				t.equal(spaceID, "!zTMspHVUBhFLLSdmnS:cadence.moe")
 				yield {
 					room_id: "!NDbIqNpJyPvfKRnNcr:cadence.moe",
-					children_state: {},
+					children_state: [],
 					guest_can_join: false,
 					num_joined_members: 2
 				}
@@ -494,7 +542,7 @@ test("web link room: successfully calls createRoom", async t => {
 				t.equal(spaceID, "!zTMspHVUBhFLLSdmnS:cadence.moe")
 				yield {
 					room_id: "!NDbIqNpJyPvfKRnNcr:cadence.moe",
-					children_state: {},
+					children_state: [],
 					guest_can_join: false,
 					num_joined_members: 2
 				}

test/test.js

@@ -17,6 +17,8 @@ const {reg} = require("../src/matrix/read-registration")
 reg.ooye.discord_token = "Njg0MjgwMTkyNTUzODQ0NzQ3.Xl3zlw.baby"
 reg.ooye.server_origin = "https://matrix.cadence.moe" // so that tests will pass even when hard-coded
 reg.ooye.server_name = "cadence.moe"
+reg.ooye.namespace_prefix = "_ooye_"
+reg.sender_localpart = "_ooye_bot"
 reg.id = "baby"
 reg.as_token = "don't actually take authenticated actions on the server"
 reg.hs_token = "don't actually take authenticated actions on the server"