Files
element-call-Github/src/state/CallViewModel/remoteMembers/Connection.ts

261 lines
9.4 KiB
TypeScript

/*
Copyright 2025 Element Creations Ltd.
Copyright 2025 New Vector Ltd.
SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
Please see LICENSE in the repository root for full details.
*/
import {
connectedParticipantsObserver,
connectionStateObserver,
} from "@livekit/components-core";
import {
ConnectionError,
type Room as LivekitRoom,
type RemoteParticipant,
} from "livekit-client";
import { type LivekitTransport } from "matrix-js-sdk/lib/matrixrtc";
import { BehaviorSubject, map } from "rxjs";
import { type Logger } from "matrix-js-sdk/lib/logger";
import { type CallMembershipIdentityParts } from "matrix-js-sdk/lib/matrixrtc/EncryptionManager";
import {
getSFUConfigWithOpenID,
type OpenIDClientParts,
type SFUConfig,
} from "../../../livekit/openIDSFU.ts";
import { type Behavior } from "../../Behavior.ts";
import { type ObservableScope } from "../../ObservableScope.ts";
import {
ElementCallError,
InsufficientCapacityError,
SFURoomCreationRestrictedError,
UnknownCallError,
} from "../../../utils/errors.ts";
export interface ConnectionOpts {
/** Whether we always try to connect to this connection via the legacy jwt endpoint. (no hash identity) */
forceOldJwtEndpoint?: boolean;
/** The media transport to connect to. */
transport: LivekitTransport;
/** The Matrix client to use for OpenID and SFU config requests. */
client: OpenIDClientParts;
/** The observable scope to use for this connection. */
scope: ObservableScope;
/** Optional factory to create the LiveKit room, mainly for testing purposes. */
livekitRoomFactory: () => LivekitRoom;
}
export class FailedToStartError extends Error {
public constructor(message: string) {
super(message);
this.name = "FailedToStartError";
}
}
export enum ConnectionState {
/** The start state of a connection. It has been created but nothing has loaded yet. */
Initialized = "Initialized",
/** `start` has been called on the connection. It aquires the jwt info to conenct to the LK Room */
FetchingConfig = "FetchingConfig",
Stopped = "Stopped",
/** The same as ConnectionState.Disconnected from `livekit-client` */
LivekitDisconnected = "disconnected",
/** The same as ConnectionState.Connecting from `livekit-client` */
LivekitConnecting = "connecting",
/** The same as ConnectionState.Connected from `livekit-client` */
LivekitConnected = "connected",
/** The same as ConnectionState.Reconnecting from `livekit-client` */
LivekitReconnecting = "reconnecting",
/** The same as ConnectionState.SignalReconnecting from `livekit-client` */
LivekitSignalReconnecting = "signalReconnecting",
}
/**
* A connection to a Matrix RTC LiveKit backend.
*
* Expose observables for participants and connection state.
*/
export class Connection {
// Private Behavior
private readonly _state$ = new BehaviorSubject<
ConnectionState | ElementCallError
>(ConnectionState.Initialized);
/**
* The current state of the connection to the media transport.
*/
public readonly state$: Behavior<ConnectionState | Error> = this._state$;
/**
* The media transport to connect to.
*/
public readonly transport: LivekitTransport;
public readonly livekitRoom: LivekitRoom;
private scope: ObservableScope;
/**
* The remote LiveKit participants that are visible on this connection.
*
* Note that this may include participants that are connected only to
* subscribe, or publishers that are otherwise unattested in MatrixRTC state.
* It is therefore more low-level than what should be presented to the user.
*/
public readonly remoteParticipants$: Behavior<RemoteParticipant[]>;
/**
* Whether the connection has been stopped.
* @see Connection.stop
* */
protected stopped = false;
/**
* Starts the connection.
*
* This will:
* 1. Request an OpenId token `request_token` (allows matrix users to verify their identity with a third-party service.)
* 2. Use this token to request the SFU config to the MatrixRtc authentication service.
* 3. Connect to the configured LiveKit room.
*
* The errors are also represented as a state in the `state$` observable.
* It is safe to ignore those errors and handle them accordingly via the `state$` observable.
* @throws {InsufficientCapacityError} if the LiveKit server indicates that it has insufficient capacity to accept the connection.
* @throws {SFURoomCreationRestrictedError} if the LiveKit server indicates that the room does not exist and cannot be created.
*/
// TODO consider an autostart pattern...
public async start(): Promise<void> {
this.logger.debug("Starting Connection");
this.stopped = false;
try {
this._state$.next(ConnectionState.FetchingConfig);
// We should already have this information after creating the localTransport.
// It would probably be better to forward this here.
const { url, jwt } = await this.getSFUConfigWithOpenID();
// If we were stopped while fetching the config, don't proceed to connect
if (this.stopped) return;
// Setup observer once we are done with getSFUConfigWithOpenID
connectionStateObserver(this.livekitRoom)
.pipe(
this.scope.bind(),
map((s) => s as unknown as ConnectionState),
)
.subscribe((lkState) => {
// It is save to cast lkState to ConnectionState as they are fully overlapping.
this._state$.next(lkState);
});
try {
await this.livekitRoom.connect(url, jwt);
} catch (e) {
// LiveKit uses 503 to indicate that the server has hit its track limits.
// https://github.com/livekit/livekit/blob/fcb05e97c5a31812ecf0ca6f7efa57c485cea9fb/pkg/service/rtcservice.go#L171
// It also errors with a status code of 200 (yes, really) for room
// participant limits.
// LiveKit Cloud uses 429 for connection limits.
// Either way, all these errors can be explained as "insufficient capacity".
if (e instanceof ConnectionError) {
if (e.status === 503 || e.status === 200 || e.status === 429) {
throw new InsufficientCapacityError();
}
if (e.status === 404) {
// error msg is "Failed to create call"
// error description is "Call creation might be restricted to authorized users only. Try again later, or contact your server admin if the problem persists."
// The room does not exist. There are two different modes of operation for the SFU:
// - the room is created on the fly when connecting (livekit `auto_create` option)
// - Only authorized users can create rooms, so the room must exist before connecting (done by the auth jwt service)
// In the first case there will not be a 404, so we are in the second case.
throw new SFURoomCreationRestrictedError();
}
}
throw e;
}
// If we were stopped while connecting, don't proceed to update state.
if (this.stopped) return;
} catch (error) {
this.logger.debug(`Failed to connect to LiveKit room: ${error}`);
this._state$.next(
error instanceof ElementCallError
? error
: error instanceof Error
? new UnknownCallError(error)
: new UnknownCallError(new Error(`${error}`)),
);
// Its okay to ignore the throw. The error is part of the state.
throw error;
}
}
protected async getSFUConfigWithOpenID(): Promise<SFUConfig> {
return await getSFUConfigWithOpenID(
this.client,
this.ownMembershipIdentity,
this.transport.livekit_service_url,
this.forceOldJwtEndpoint,
this.transport.livekit_alias,
// For the remote members we intentionally do not pass a delayEndpointBaseUrl.
undefined,
// and no delayId.
undefined,
this.logger,
);
}
/**
* Stops the connection.
*
* This will disconnect from the LiveKit room.
* If the connection is already stopped, this is a no-op.
*/
public async stop(): Promise<void> {
this.logger.debug(
`Stopping connection to ${this.transport.livekit_service_url}`,
);
if (this.stopped) return;
await this.livekitRoom.disconnect();
this._state$.next(ConnectionState.Stopped);
this.stopped = true;
}
private readonly client: OpenIDClientParts;
private readonly logger: Logger;
private readonly forceOldJwtEndpoint: boolean;
/**
* Creates a new connection to a matrix RTC LiveKit backend.
*
* @param opts - Connection options {@link ConnectionOpts}.
*
* @param logger - The logger to use.
*/
public constructor(
opts: ConnectionOpts,
logger: Logger,
private ownMembershipIdentity: CallMembershipIdentityParts,
) {
this.forceOldJwtEndpoint = opts.forceOldJwtEndpoint ?? false;
this.logger = logger.getChild("[Connection]");
this.logger.info(
`Creating new connection to ${opts.transport.livekit_service_url} ${opts.transport.livekit_alias}`,
);
const { transport, client, scope } = opts;
this.scope = scope;
this.livekitRoom = opts.livekitRoomFactory();
this.transport = transport;
this.client = client;
this.remoteParticipants$ = scope.behavior(
// Only tracks remote participants
connectedParticipantsObserver(this.livekitRoom),
);
scope.onEnd(() => {
this.logger.info(`Connection scope ended, stopping connection`);
void this.stop();
});
}
}