Week 7

The chrome extension supports <iframe> tags with the 'src' attribute pointing to a gnocchi file on the server now. Also, I change the way the browser interprets a gnocchi file to prevent the possible code injection attack. Rather than "text/html", the modified content-type of a gnocchi file is "text/plain", so all the injected codes would be regarded as just plain text by the chrome browser.

To resolve the <iframe> reference, I add two listeners: one is added on the event "chrome.webRequest.onHeadersReceived", which is fired when the request header is received to check for gnocchi files, and the other one is added on the event "chrome.webNavigation.onCompleted", which is fired when the document resources are completely loaded and initialized.

For now, I'm using a global variable to record the urls of the gnocchi files. I know that using global variables is not a good practice in coding, but it seems to me that it is the best solution. Alternatives are message sending and local storage. Message sending is more tedious and turning the code even less readable than global variables. Besides, I have no idea how to embed a listener on the event "chrome.webNavigation.onCompleted" inside another listener on the event of receiving message at this point. Anyway, I will manage message sending to see how well it works if I have time. As for local storage, that is a inferior choice considering the performance of the extension. Also, local storage runs asynchronously, competition between different processes makes the extension less reliable.

Here is the result of the test case with 20 <iframe> tags in a webpage (some of them are not visible due to the limited size):

Key management on the client side is my next step. I will take a look at google's e2e library to learn more about how they manage it. Furthermore, message sending between different listeners of the extension is also in my plan so as to get rid of annoying global variables.