Register security exception automatically when a cert error page is initially shown, on Firefox ESR60

autoconfig.cfg

// the first line is always ignored by Firefox.

const autoAcceptExceptionFor = (host, port = 443) => {
  const { classes: Cc, interfaces: Ci, utils: Cu } = Components;
  const exceptionURL = port == 443 ? `https://${host}` : `https://${host}:${port}`;

  const { Services } = Cu.import('resource://gre/modules/Services.jsm', {});
  const observer = {
    observe(aSubject, aTopic, aData) {
      switch (aTopic) {
        case 'domwindowopened':
          if (!aSubject.QueryInterface(Ci.nsIInterfaceRequestor)
                       .getInterface(Ci.nsIWebNavigation)
                       .QueryInterface(Ci.nsIDocShell)
                       .QueryInterface(Ci.nsIDocShellTreeNode || Ci.nsIDocShellTreeItem) // nsIDocShellTreeNode is merged to nsIDocShellTreeItem by https://bugzilla.mozilla.org/show_bug.cgi?id=331376
                       .QueryInterface(Ci.nsIDocShellTreeItem)
                       .parent) {
            const win = aSubject.QueryInterface(Ci.nsIDOMWindow);
            win.addEventListener('load', () => tryHandleWindow(win), { once: true });
          }
          return;
      }
    },
    QueryInterface(aIID) {
      if (!aIID.equals(Ci.nsIObserver) &&
          !aIID.equals(Ci.nsISupports)) {
        throw Components.results.NS_ERROR_NO_INTERFACE;
      }
      return this;
    }
  };

  const waitUntilEventOrTimeout = (target, type, timeout) => {
    return new Promise((resolve, reject) => {
      const win = (target.ownerDocument || target).defaultView || target;
      const listener = () => {
        target.removeEventListener(type, listener);
        win.clearTimeout(timer);
        resolve();
      };
      const timer = win.setTimeout(listener, timeout);
      target.addEventListener(type, listener);
    });
  };

  const WW = Cc['@mozilla.org/embedcomp/window-watcher;1'].getService(Ci.nsIWindowWatcher);
  const teardown = () => {
    WW.unregisterNotification(observer);
    //if (tab)
    //  tab.ownerDocument.defaultView.gBrowser.removeTab(tab);
  };

  let tab;
  const tryHandleWindow = async (win) => {
    switch (win.location.href.replace(/(\?.*)(#.*)$/, '')) {
      case 'chrome://browser/content/browser.xul': {
        await new Promise((resolve, reject) => {
          win.addEventListener('MozAfterPaint', resolve, { once: true });
        });

        const certOverride = Cc['@mozilla.org/security/certoverride;1'].getService(Ci.nsICertOverrideService);
        const hash = {}, fingerprint = {}, flags = {}, temporary = {};
        if (!certOverride ||
            (certOverride.getValidityOverride &&
             certOverride.getValidityOverride(host, port, hash, fingerprint, flags, temporary))) {
          teardown();
          return;
        }

        //win.openNewTabWith(exceptionURL);
        await new Promise((resolve, reject) => {
          const listener = (event) => {
            if (event.detail.changed != 'busy' ||
                event.target.getAttribute('busy') == 'true')
              return;
            win.setTimeout(() => {
              const uri = event.target.linkedBrowser.lastURI || event.target.linkedBrowser.currentURI;
              if (!uri || uri.spec.indexOf(exceptionURL) != 0)
                return;
              win.document.removeEventListener('TabAttrModified', listener);
              tab = event.target;
              resolve();
            }, 100);
          };
          win.document.addEventListener('TabAttrModified', listener);
        });

        const browser = tab.linkedBrowser;
        browser.messageManager.loadFrameScript('data:text/javascript,(' + (async (waitUntilEventOrTimeout) => {
          const doc = docShell.QueryInterface(Components.interfaces.nsIWebNavigation).document;
          const win = doc.defaultView;
          await waitUntilEventOrTimeout(doc, 'AboutNetErrorLoad', 500);

          const advancedButton = doc.getElementById('advancedButton');
          if (advancedButton) {
            advancedButton.dispatchEvent(new win.MouseEvent('click', { button: 0 }));
            const exceptionDialogButton = doc.getElementById('exceptionDialogButton');
            if (exceptionDialogButton) {
              exceptionDialogButton.dispatchEvent(new win.MouseEvent('click', { button: 0 }));
              return; /* success case, go to next step: exceptionDialog */
            }
          }
          /* failure case */
        }).toSource() + ')(' + waitUntilEventOrTimeout.toSource() + ')', false, false);
      }; break;

      case 'chrome://pippki/content/exceptionDialog.xul': {
        if (!tab)
          return;
        win.addEventListener('unload', () => {
          teardown();
          tab.linkedBrowser.reload();
        }, { once: true });
        await waitUntilEventOrTimeout(win, 'load', 200);
        const timer = win.setInterval(() => {
          if (!win.gCert || win.gChecking)
            return;
          win.clearInterval(timer);
          win.document.documentElement.getButton('extra1').click();
        }, 100);
      }; break;
    }
  };

  WW.registerNotification(observer);
};

autoAcceptExceptionFor('hostname', 8080);