Beginner Assistance - Where does this code belong? - javascript

I'm trying to develop a firefox extension that inserts additional HTTP header fields into outgoing HTTP requests (to interface with an apache extension i'm concurrently developing).
While I understand the individual components of an extension and understand the basic tutorials that are presented on the web, I'm finding it difficult going from the "Hello World" tutorial extensions, into developing a full blown extension.
The sample code I am wanting to adapt for my purposes is presented at the bottom of Setting HTTP request headers.
I am wondering, where in the extension hierarchy should this code be placed and how is such code called/constructed/activated, will it run automatically when the extension is initialised?
Thanks in advance.

For a basic extension, you would place your code in the chrome/content directory of the extension. You would hook this content into Firefox using an overlay. While overlays are usually xul content (buttons, etc) they can be anything. Including a script tag which would load fire off your Javascript code.

That code is an XPCOM component and goes into a components/<some name>.js file.
You should read up on XPCOM components if you want to dig it, but yes, .js files in components are loaded at startup. Such files contain registration code (starts at the var myModule = { line in that example), which tells Firefox whether the component defined in the file is available upon request or should it be instantiated automatically.
In that example you can see the component getting registered to be notified of the application's startup:
catMgr.addCategoryEntry("app-startup", this.myName, this.myProgID, true, true);
and when handling the app-startup notification it registers itself for the http-on-modify-request notification:
os.addObserver(this, "http-on-modify-request", false);

Related

How to Change Firefox Proxy Settings Programmatically?

I'm launching Firefox via command line and I'd like to launch a specific Firefox Profile with a proxy. According to this answer on Stackoverflow, Firefox proxy settings are stored in pref.js in the Firefox Profile folder and it is necessary to edit this file to launch FF with a proxy.
I've edited the file as follows:
user_pref("network.proxy.ftp", "1.0.0.1");
user_pref("network.proxy.ftp_port", 00000);
user_pref("network.proxy.gopher", "1.0.0.1");
user_pref("network.proxy.gopher_port", 00000);
user_pref("network.proxy.http", "1.0.0.1");
user_pref("network.proxy.http_port", 22222);
user_pref("network.proxy.no_proxies_on", "localhost, 1.0.0.1");
user_pref("network.proxy.socks", "1.0.0.1");
user_pref("network.proxy.socks_port", 00000);
user_pref("network.proxy.ssl", "1.0.0.1");
user_pref("network.proxy.ssl_port", 00000);
user_pref("network.proxy.type", 1);
Note: the IP address and port used above are for demonstration purposes.
However, I'm encountering two problems:
1) Firefox completely ignores these settings and launches FF without any proxy at all
2) When Firefox exits the text modification is reverted/deleted
Note: When I edited the text file above, Firefox was not running. I know there's a disclaimer at the top of prefs.js:
If you make changes to this file while the application is running, the
changes will be overwritten when the application exits.
But there were no live instances of Firefox running at the time I edited the above file.
Manually creating different FF Profiles (as suggested by another user) with different proxies is not an option as everything needs to be done programmatically, without manual intervention.
Does Firefox still support linking proxy via pref.js? If not, what is the current working solution to launch Firefox via command line with a proxy in Java?
Thanks
A proxy-autoconfig file is what you are looking for.
Docs here.
Define a file name.pac, that contains the javascript function
function FindProxyForURL(url, host)
Inside the file you can use any javscript you'd like to decide what proxy to use. Set the path to your .pac file in the firefox settings, under auto-config proxy. Remember to use a file url.
To setup automatic file switching, simply configure firefox to point towards a single file, and overwrite the file programmatically every time you want it to change. You could keep copies of all options, and simply copy an option file into the target file right before running.
An example of a super simple pac file is this:
function FindProxyForURL (url, host) {
return 'PROXY proxy.example.com:8080; DIRECT';
}
It will always return the identical proxy for all endpoints.
Passwords are not explicitly supported by the pac standard, but there are different ways to approach this. Firefox will prompt you for a login if it thinks it needs one, and you could also embed the password into the url (username:password#proxy.example.com). Additionally, a tool like proxy login automator could allow you to use passwords and to dynamically set the proxy without having to fight with firefox.

google chrome extension rejected http request

I've prepared chrome extension that was rejected to be published because of some issues (they haven't specified what is wrong exactly). Below message i recieved from them about rejection:
Your item "[name of extension]" [here some kind of id] is
being taken down as it currently violates the section of the Developer
Program Policy relating to Malicious Products as its obfuscating a
part of code. Per our policies, where possible, make as much of your
code visible in the package as you can. If some of your app's logic is
hidden and it appears to be suspicious, we may remove it.
To have your item reinstated, please make any necessary changes to
ensure:
All of the files and code are included in the item’s package.
All code inside the package is human readable (no obfuscated or minified code).
Avoid requesting or executing remotely hosted code (including by referencing remote javascript files or executing code obtained by XHR requests).
Most probably they don't like this part of my code
$.get('http://mydomain/catalogue/message.php?date=' + today, function() {})
.done(function(responseMessage) {
chrome.notifications.create(
'reminder'
,{type: 'basic'
,title: responseTopic
,iconUrl: "small.jpg"
,message: responseMessage}
,function(notificationId) {});
});
This request suppose to answer with a text message to notify the user. Is this a threat? Can javascript be injected this way? If yes, can I strip it somehow?

Is there an alternative to preprocessorScript for Chrome DevTools extensions?

I want to create a custom profiler for Javascript as a Chrome DevTools Extension. To do so, I'd have to instrument all Javascript code of a website (parse to AST, inject hooks, generate new source). This should've been easily possible using chrome.devtools.inspectedWindow.reload() and its parameter preprocessorScript described here: https://developer.chrome.com/extensions/devtools_inspectedWindow.
Unfortunately, this feature has been removed (https://bugs.chromium.org/p/chromium/issues/detail?id=438626) because nobody was using it.
Do you know of any other way I could achieve the same thing with a Chrome Extension? Is there any other way I can replace an incoming Javascript source with a changed version? This question is very specific to Chrome Extensions (and maybe extensions to other browsers), I'm asking this as a last resort before going a different route (e.g. dedicated app).
Use the Chrome Debugging Protocol.
First, use DOMDebugger.setInstrumentationBreakpoint with eventName: "scriptFirstStatement" as a parameter to add a break-point to the first statement of each script.
Second, in the Debugger Domain, there is an event called scriptParsed. Listen to it and if called, use Debugger.setScriptSource to change the source.
Finally, call Debugger.resume each time after you edited a source file with setScriptSource.
Example in semi-pseudo-code:
// Prevent code being executed
cdp.sendCommand("DOMDebugger.setInstrumentationBreakpoint", {
eventName: "scriptFirstStatement"
});
// Enable Debugger domain to receive its events
cdp.sendCommand("Debugger.enable");
cdp.addListener("message", (event, method, params) => {
// Script is ready to be edited
if (method === "Debugger.scriptParsed") {
cdp.sendCommand("Debugger.setScriptSource", {
scriptId: params.scriptId,
scriptSource: `console.log("edited script ${params.url}");`
}, (err, msg) => {
// After editing, resume code execution.
cdg.sendCommand("Debugger.resume");
});
}
});
The implementation above is not ideal. It should probably listen to the breakpoint event, get to the script using the associated event data, edit the script and then resume. Listening to scriptParsed and then resuming the debugger are two things that shouldn't be together, it could create problems. It makes for a simpler example, though.
On HTTP you can use the chrome.webRequest API to redirect requests for JS code to data URLs containing the processed JavaScript code.
However, this won't work for inline script tags. It also won't work on HTTPS, since the data URLs are considered unsafe. And data URLs are can't be longer than 2MB in Chrome, so you won't be able to redirect to large JS files.
If the exact order of execution of each script isn't important you could cancel the script requests and then later send a message with the script content to the page. This would make it work on HTTPS.
To address both issues you could redirect the HTML page itself to a data URL, in order to gain more control. That has a few negative consequences though:
Can't reload page because URL is fixed to data URL
Need to add or update <base> tag to make sure stylesheet/image URLs go to the correct URL
Breaks ajax requests that require cookies/authentication (not sure if this can be fixed)
No support for localStorage on data URLs
Not sure if this works: in order to fix #1 and #4 you could consider setting up an HTML page within your Chrome extension and then using that as the base page instead of a data URL.
Another idea that may or may not work: Use chrome.debugger to modify the source code.

Can I fire up a Chrome extension API from code?

Is it possible to launch a Google Chrome extension within a website? E.g run some javascript that will launch the extensions UI?
I'm building a web-app that will allow users to take screenshots of their desktop and edit them. I've got a sample extension up and running using dektopCapture but it is an 'app' style of an extension.
It allows to select a window to stream from, then take a
snapshot within the extension UI(using a button) that is saved as an image string
My question is:
Is it possible to fire up the desktopCapture UI (the window that gets the available windows to stream from), from within my web-app, maybe a button, take the stream and place it on a canvas/HTML5 video element within my web-app?
I'm figuring that I could hook-up an event-listener within the extension and use runtime.onMessage to post a message from within my app
Notes:
If there's a more intuitive way to do this, I can go that route - e.g If I could keep as much interaction within the web-app with just the extension running in the background, that would be even better.
The extension is of type browser_action but I want it to be applicable to a single page(the app's webpage) so if it can be used in a page_action I'd prefer that instead. There's really no need to have browser_action icon if I can trigger this from within a webpage
I'm also planning to build a FF extension so any insights there are also appreciated.
So I'm answering my own question.
I've managed to get it working using externally_connectables.
The externally_connectable manifest property declares which
extensions, apps, and web pages can connect to your extension via
runtime.connect and runtime.sendMessage.
1. Declare app/webpage in manifest.json
Just declare your web-app/page within your manifest.json as an externally_connectable.
E.g I wanted to connect my app is hosted on Github Pages and I have a domain name of https://nicholaswmin.github.io, so it does a bit like this:
"externally_connectable": {
"matches": ["https://nicholaswmin.github.io/*"]
}, //rest of manifest.json
2. Set up event listener for messages in background.js
Then set up an event listener in your background.js like so:
chrome.runtime.onMessageExternal.addListener(function(request, sender, sendResponse) {
//Stuff you want to run goes here, even desktopCapture calls
});
3. Send message from your web/app page
And call it from within your web-app/website like this:
chrome.runtime.sendMessage("APP ID GOES HERE",
{data: { key : "capture"}});
Make sure that your website is correctly declared as an externally_connectable in your manifest.json and that you are passing the app-id when sending the message

How do I check if firebug is installed with javascript?

Here it is described how to check if Firebug is installed by checking if an image of firebug exists: http://webdevwonders.com/detecting-firefox-add-ons/
But it seems to be a bit outdated, cause the images he uses there don't exist anymore in firebug.
the firebug chrome.manifest looks like:
content firebug content/firebug/ contentaccessible=yes
...
but in the whole addon I only find one png now, and that is placed in the rootfolder of the addon. But some other content is accessible, for example: chrome://firebug/content/trace.js
Ho
So, in gerneral:
How do I make an image accessible that resides inside a Firefox SDK Addon?
I program an Addon and I want to make an image ok.png available to all javascripts in Firefox.
I added the image in the data folder and added a chrome.manifest
content response-timeout-24-hours data/
content response-timeout-24-hours data/ contentaccessible=yes
But no way to call it via a URL like
chrome://response-timeout-24-hours/data/ok.png
How do the paths belong together? which is relative to which?
I created a Bug report here.
So if you want to make your add-on detectable you need another approach:
you can use a PageMod to attach a content script that would wait for a
message from your web-app and "respond" by sending another message
back to your app. you would know that if you don't receive the
response, your addon is not installed. check out the documentation for
more details:
https://developer.mozilla.org/en-US/Add-ons/SDK/High-Level_APIs/page-mod
I used this to make my add-on detectable.

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