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Encapsulate tun2socks restart behavior
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@alalamav
alalamav committed Oct 23, 2019
1 parent b38333d commit b946211
Showing 1 changed file with 96 additions and 97 deletions.
193 changes: 96 additions & 97 deletions src/electron/process_manager.ts
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Expand Up @@ -71,34 +71,28 @@ function testTapDevice() {
}

// Establishes a full-system VPN with the help of Outline's routing daemon and child process
// tun2socks. Follows the Mediator pattern in that none of the three "helpers" know
// anything about the others.
// tun2socks. Follows the Mediator pattern in that none of the "helpers" know anything about
// the others.
//
// In addition to the basic lifecycle of the three helper processes, this handles a few special
// situations:
// - repeat the UDP test when the network changes and restart tun2socks if the result has changed
// - silently restart tun2socks when the system resumes after suspend (Windows only)
// In addition to the basic lifecycle of the helper processes, this class restarts tun2socks
// on network changes to perform connectivity checks.
export class ConnectionManager {
private readonly routing: RoutingDaemon;
private readonly tun2socks: Tun2socks;

// Extracted out to an instance variable because in certain situations, notably a change in UDP
// support, we need to stop and restart tun2socks *without notifying the client* and this allows
// us swap the listener in and out.
private tun2socksExitListener?: () => void;

// See #resumeListener.
private terminated = false;

private readonly onAllHelpersStopped: Promise<void>;

private reconnectingListener?: () => void;

private reconnectedListener?: () => void;

constructor(
config: cordova.plugins.outline.ServerConfig, private isAutoConnect: boolean) {
this.tun2socks = new Tun2socks(config);
let tun2socksExitListener: (() => void) | undefined;
const onTun2socksExit = () => {
if (tun2socksExitListener) {
tun2socksExitListener();
}
};
this.tun2socks = new Tun2socks(config, onTun2socksExit);
this.routing = new RoutingDaemon(config.host || '', isAutoConnect);

// These Promises, each tied to a helper process' exit, is key to the instance's
Expand All @@ -108,7 +102,7 @@ export class ConnectionManager {
const exits = [
this.routing.onceDisconnected,
new Promise<void>((fulfill) => {
this.tun2socksExitListener = fulfill;
tun2socksExitListener = fulfill;
})
];
Promise.race(exits).then(() => {
Expand All @@ -117,15 +111,10 @@ export class ConnectionManager {
});
this.onAllHelpersStopped = Promise.all(exits).then(() => {
console.log('all helpers have exited');
this.terminated = true;
});

// Handle network changes and, on Windows, suspend events.
this.routing.onNetworkChange = this.networkChanged.bind(this);
if (isWindows) {
powerMonitor.on('suspend', this.suspendListener.bind(this));
powerMonitor.on('resume', this.resumeListener.bind((this)));
}
}

// Fulfills once all three helpers have started successfully.
Expand All @@ -136,28 +125,16 @@ export class ConnectionManager {

// Don't validate credentials on boot: if the key was revoked, we want the system to stay
// "connected" so that traffic doesn't leak.
try {
await this.tun2socks.start(!this.isAutoConnect);
} catch (e) {
if (this.tun2socksExitListener) {
this.tun2socksExitListener();
}
throw e;
}
this.tun2socks.onExit = this.tun2socksExitListener;
await this.tun2socks.start(!this.isAutoConnect);

await this.routing.start();
}

private async networkChanged(status: ConnectionStatus) {
if (status === ConnectionStatus.CONNECTED) {
if (this.tun2socks.isRunning) {
// Test whether UDP availability has changed.
await this.restartTun2socks();
} else {
// Windows: the network was connected after the system resumed from suspend.
await this.tun2socks.start(true);
}
// (Re)start tun2socks to check for changes in UDP connectivity.
// Windows: following a system suspend/resume, this will start tun2socks.
await this.tun2socks.start(true);

if (this.reconnectedListener) {
this.reconnectedListener();
Expand All @@ -171,43 +148,8 @@ export class ConnectionManager {
}
}

private suspendListener() {
console.log('suspend listener invoked');
// Windows: when the system suspends, tun2socks terminates due to the TAP device getting closed.
// Swap out the current listener, restart once the system resumes.
this.tun2socks.onExit = () => {
console.log('tun2socks stopped as a result of system suspend');
};
}

private resumeListener() {
if (this.terminated) {
// NOTE: Cannot remove resume listeners - Electron bug?
console.error('resume event invoked but this connection is terminated - doing nothing');
return;
}
console.log('restoring tun2socks exit listener after resume');
this.tun2socks.onExit = this.tun2socksExitListener;
}

private async restartTun2socks() {
// Swap out the current listener, restart once the current process exits.
return new Promise(resolve => {
this.tun2socks.onExit = async () => {
console.log('restarting tun2socks');
this.tun2socks.onExit = this.tun2socksExitListener;
await this.tun2socks.start(true);
resolve();
};
this.tun2socks.stop();
});
}

// Use #onceStopped to be notified when the connection terminates.
stop() {
powerMonitor.removeListener('suspend', this.suspendListener.bind(this));
powerMonitor.removeListener('resume', this.resumeListener.bind(this));

try {
this.routing.stop();
} catch (e) {
Expand Down Expand Up @@ -253,7 +195,7 @@ class ChildProcessHelper {

constructor(private path: string) {}

protected launch(args: string[]) {
launch(args: string[]) {
this.process = spawn(this.path, args);
this.running = true;

Expand Down Expand Up @@ -307,12 +249,87 @@ class ChildProcessHelper {
}
}

class Tun2socks extends ChildProcessHelper {
constructor(private config: cordova.plugins.outline.ServerConfig) {
super(pathToEmbeddedBinary('go-tun2socks', 'tun2socks'));
// Class to manage the lifecycle of tun2socks. Silently restarts the process when
// the system resumes after suspend (Windows only).
class Tun2socks {
private process: ChildProcessHelper;

constructor(private config: cordova.plugins.outline.ServerConfig,
private exitListener?: () => void) {
this.process = new ChildProcessHelper(pathToEmbeddedBinary('go-tun2socks', 'tun2socks'));
}

async start(checkConnectivity: boolean) {
if (this.process.isRunning) {
return this.restart(checkConnectivity);
}

this.process.launch(this.getProcessArgs(checkConnectivity));

return new Promise((resolve, reject) => {
// Declare success when tun2socks is running.
this.process.onStdout = (data?: string | Buffer) => {
if (data && data.toString().includes('tun2socks running')) {
this.process.onStdout = undefined;
this.process.onExit = this.exitListener;
if (isWindows) {
powerMonitor.on('suspend', this.suspendListener.bind(this));
powerMonitor.on('resume', this.resumeListener.bind((this)));
}
resolve();
}
};

// Wait for an early exit due to connectvity failures.
this.process.onExit = (code?: number, signal?: string) => {
console.log('tun2socks exited with code', code);
if (this.exitListener) {
this.exitListener();
}
// code === 0 should not happen unless invoked with `-version`;
// treat it like an unexpected error.
reject(errors.fromErrorCode(code || errors.ErrorCode.UNEXPECTED));
};
});
}

stop() {
if (isWindows) {
powerMonitor.removeListener('suspend', this.suspendListener.bind(this));
powerMonitor.removeListener('resume', this.resumeListener.bind(this));
}
this.process.stop();
}

private async restart(checkConnectivity: boolean) {
// Swap out the current listener, restart once the current process exits.
return new Promise(resolve => {
this.process.onExit = async () => {
console.log('restarting tun2socks');
await this.start(checkConnectivity);
resolve();
};
this.stop();
});
}

private suspendListener() {
console.log('system suspending');
// Windows: when the system suspends, tun2socks terminates due to the TAP device getting closed.
// Swap out the current listener, restart once the system resumes.
this.process.onExit = () => {
console.log('tun2socks stopped as a result of system suspend');
};
powerMonitor.removeListener('suspend', this.suspendListener.bind(this));
}

private resumeListener() {
console.log('restoring tun2socks exit listener after resume');
this.process.onExit = this.exitListener;
powerMonitor.removeListener('resume', this.resumeListener.bind(this));
}

private getProcessArgs(checkConnectivity: boolean): string[] {
// ./tun2socks.exe \
// -tunName outline-tap0 -tunDNS 1.1.1.1,9.9.9.9 \
// -tunAddr 10.0.85.2 -tunGw 10.0.85.1 -tunMask 255.255.255.0 \
Expand All @@ -332,24 +349,6 @@ class Tun2socks extends ChildProcessHelper {
if (checkConnectivity) {
args.push('-checkConnectivity');
}
this.launch(args);

return new Promise((resolve, reject) => {
// Declare success when tun2socks is running.
this.onStdout = (data?: string | Buffer) => {
if (data && data.toString().includes('tun2socks running')) {
this.onStdout = undefined;
resolve();
}
};

// Wait for an early exit due to connectvity failures.
this.onExit = (code?: number, signal?: string) => {
console.log('tun2socks exited with code', code);
// code === 0 should not happen unless invoked with `-version`;
// treat it like an unexpected error.
reject(errors.fromErrorCode(code || errors.ErrorCode.UNEXPECTED));
};
});
return args;
}
}

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