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| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 | import { E } from '@endo/eventual-send';
import {
makeBackgroundCapTP,
makeCapTPNotification,
isCapTPNotification,
getCapTPMessage,
isConsoleForwardMessage,
handleConsoleForwardMessage,
} from '@metamask/kernel-browser-runtime';
import type { CapTPMessage } from '@metamask/kernel-browser-runtime';
import defaultSubcluster from '@metamask/kernel-browser-runtime/default-cluster';
import { delay, isJsonRpcMessage, stringify } from '@metamask/kernel-utils';
import type { JsonRpcMessage } from '@metamask/kernel-utils';
import { Logger } from '@metamask/logger';
import { ChromeRuntimeDuplexStream } from '@metamask/streams/browser';
defineGlobals();
const OFFSCREEN_DOCUMENT_PATH = '/offscreen.html';
const logger = new Logger('background');
let bootPromise: Promise<void> | null = null;
// With this we can click the extension action button to wake up the service worker.
chrome.action.onClicked.addListener(() => {
globalThis.kernel !== undefined &&
E(globalThis.kernel).ping().catch(logger.error);
});
// Install/update
chrome.runtime.onInstalled.addListener(() => {
start();
});
// Browser restart / profile startup
chrome.runtime.onStartup.addListener(() => {
start();
});
// Messages or connections can also kick us awake
chrome.runtime.onMessage.addListener((_msg, _sender, sendResponse) => {
start();
sendResponse(true);
return false;
});
chrome.runtime.onConnect.addListener(() => {
start();
});
/** Idempotent starter used by all triggers */
function start(): void {
bootPromise ??= main()
.catch((error) => {
logger.error(error);
})
.finally(() => {
// Let future triggers re-run main() if needed
bootPromise = null;
});
}
/**
* Ensure that the offscreen document is created and avoid duplicate creation.
*/
async function ensureOffscreen(): Promise<void> {
try {
if (
chrome.offscreen.hasDocument &&
(await chrome.offscreen.hasDocument())
) {
return;
}
} catch {
// ignore and attempt creation
}
await chrome.offscreen.createDocument({
url: OFFSCREEN_DOCUMENT_PATH,
reasons: [chrome.offscreen.Reason.IFRAME_SCRIPTING],
justification: `Surely you won't object to our capabilities?`,
});
}
/**
* The main function for the background script.
*/
async function main(): Promise<void> {
await ensureOffscreen();
// Without this delay, sending messages via the chrome.runtime API can fail.
await delay(50);
// Create stream for CapTP messages
const offscreenStream = await ChromeRuntimeDuplexStream.make<
JsonRpcMessage,
JsonRpcMessage
>(chrome.runtime, 'background', 'offscreen', isJsonRpcMessage);
// Set up CapTP for E() based communication with the kernel
const backgroundCapTP = makeBackgroundCapTP({
send: (captpMessage: CapTPMessage) => {
const notification = makeCapTPNotification(captpMessage);
offscreenStream.write(notification).catch((error) => {
logger.error('Failed to send CapTP message:', error);
});
},
});
// Get the kernel remote presence
const kernelP = backgroundCapTP.getKernel();
globalThis.kernel = kernelP;
// Handle incoming messages from offscreen (CapTP and console-forward)
const drainPromise = offscreenStream.drain((message) => {
if (isConsoleForwardMessage(message)) {
handleConsoleForwardMessage(message);
} else if (isCapTPNotification(message)) {
const captpMessage = getCapTPMessage(message);
backgroundCapTP.dispatch(captpMessage);
} else {
throw new Error(`Unexpected message: ${stringify(message)}`);
}
});
drainPromise.catch(logger.error);
try {
await E(kernelP).ping();
await startDefaultSubcluster();
} catch (error) {
offscreenStream.throw(error as Error).catch(logger.error);
}
try {
await drainPromise;
} catch (error) {
const finalError = new Error('Offscreen connection closed unexpectedly', {
cause: error,
});
backgroundCapTP.abort(finalError);
throw finalError;
}
}
/**
* Idempotently starts the default subcluster.
*/
async function startDefaultSubcluster(): Promise<void> {
const status = await E(globalThis.kernel).getStatus();
if (status.subclusters.length === 0) {
const result = await E(globalThis.kernel).launchSubcluster(
defaultSubcluster,
);
logger.info(`Default subcluster launched: ${JSON.stringify(result)}`);
} else {
logger.info('Subclusters already exist. Not launching default subcluster.');
}
}
/**
* Define globals accessible via the background console.
*/
function defineGlobals(): void {
Object.defineProperty(globalThis, 'kernel', {
configurable: false,
enumerable: true,
writable: true,
value: undefined,
});
Object.defineProperty(globalThis, 'E', {
value: E,
configurable: false,
enumerable: true,
writable: false,
});
}
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