worker that enforces access by address

address-worker.js

// 21 June 2023
// poc: create a worker that enforces access by address

var source = `
self.address;

self.onmessage = function (e) {
  console.warn("init");

  if (e.data.action !== 'init') {
    return console.error("must call init before any other action,", e.data.action);
  }

  var blob = new Blob([Date.now()], { type: "text/plain" });

  self.address = URL.createObjectURL(blob);
  self.postMessage(Object.assign({}, { address }));

  self.onmessage = self.onrequest;
}

self.onrequest = function (request) {
  var { action, value = "", address } = Object(request.data);

  console.log('inside worker', { action, value, address }, address === self.address);

  if (address !== self.address) {
    return console.error("invalid request, address does not match,", { action, value, address });
  }

  console.log("correct address for", action);

  var result = typeof self.actions[action] == 'function'
    ? self.actions[action](value)
    : "";

  if (result) {
    self.postMessage(Object.assign({ action }, result));
  }
}

self.actions = {
  echo(value) {
    console.log('echo:', value);

    return { value };
  }
}

`;
var blob = new Blob([source], { type: "text/javascript" })
var url = URL.createObjectURL(blob);
var worker = new Worker(url);
URL.revokeObjectURL(url);

var address;

var oninit = function (e) {
  console.info("message from worker");
  console.warn(e.data.address);

  address = e.data.address;
  worker.onmessage = onresponse;
}

var onresponse = function (response) {
  console.info("response from worker");
  console.warn(response.data);
}

worker.onmessage = oninit;

worker.postMessage({action: 'poke'});
worker.postMessage({action: 'init'});
worker.postMessage({action: 'init'});
worker.postMessage({action: 'init'});
worker.postMessage({action: 'init'});

setTimeout(() => {
  worker.postMessage({action: 'init'});
  worker.postMessage({action: 'echo', value: Date.now(), address});
}, 500);