How to cancel webRequest silently in chrome extension - javascript

I'm re-posting my question from Chromium-extensions google group here.
In my extension, I want to cancel some webRequests based on url pattern. My problem is that, if I return {cancel:true} in the onBeforeRequest event listener, the browser would redirect to a page telling me that the request is blocked by some extension. But I just want to cancel the request silently(as nothing happened).
I have also tried to return {redirectUrl:""} in the onBeforeRequest event listener, the console would log an error saying that "" was not a valid URL, and a bar appeared at the bottom of the browser, saying "Waiting for extension". To dismiss that bar, I then run content script "window.stop()" in that web page. That works sometimes, but not always. So I wonder if someone has any better solution. Thanks!!

You should use "javascript:" url instead :
{
redirectUrl:"javascript:"
}

return {redirectUrl: 'javascript:void(0)'};

Redirect to a page which replies with HTTP status code 204, e.g. https://robwu.nl/204 This is my website, and I do not log any traffic to this URL.
The specification demands the following behavior for a response with HTTP status 204:
If the client is a user agent, it SHOULD NOT change its document view from that which caused the request to be sent. This response is primarily intended to allow input for actions to take place without causing a change to the user agent's active document view, although any new or updated metainformation SHOULD be applied to the document currently in the user agent's active view.
Here is a simple example, an extension that silently blocks all requests to YouTube:
chrome.webRequest.onBeforeRequest.addListener(function(details) {
var scheme = /^https/.test(details.url) ? 'https' : 'http';
return { redirectUrl: scheme + '://robwu.nl/204' };
}, {
urls: ['*://www.youtube.com/*'] // Example: Block all requests to YouTube
}, ['blocking']);
This example redirects to http://robwu.nl/204 or https://robwu.nl/204 depending on the requests's scheme, to avoid mixed content warnings.
To get this example to work, you need to declare the webRequest, webRequestBlocking and host permissions for the site in the manifest file.

Related

How can I cancel consecutive requests to my server? [duplicate]

What would cause a page to be canceled? I have a screenshot of the Chrome Developer Tools.
This happens often but not every time. It seems like once some other resources are cached, a page refresh will load the LeftPane.aspx. And what's really odd is this only happens in Google Chrome, not Internet Explorer 8. Any ideas why Chrome would cancel a request?
We fought a similar problem where Chrome was canceling requests to load things within frames or iframes, but only intermittently and it seemed dependent on the computer and/or the speed of the internet connection.
This information is a few months out of date, but I built Chromium from scratch, dug through the source to find all the places where requests could get cancelled, and slapped breakpoints on all of them to debug. From memory, the only places where Chrome will cancel a request:
The DOM element that caused the request to be made got deleted (i.e. an IMG is being loaded, but before the load happened, you deleted the IMG node)
You did something that made loading the data unnecessary. (i.e. you started loading a iframe, then changed the src or overwrite the contents)
There are lots of requests going to the same server, and a network problem on earlier requests showed that subsequent requests weren't going to work (DNS lookup error, earlier (same) request resulted e.g. HTTP 400 error code, etc)
In our case we finally traced it down to one frame trying to append HTML to another frame, that sometimes happened before the destination frame even loaded. Once you touch the contents of an iframe, it can no longer load the resource into it (how would it know where to put it?) so it cancels the request.
status=canceled may happen also on ajax requests on JavaScript events:
<script>
$("#call_ajax").on("click", function(event){
$.ajax({
...
});
});
</script>
<button id="call_ajax">call</button>
The event successfully sends the request, but is is canceled then (but processed by the server). The reason is, the elements submit forms on click events, no matter if you make any ajax requests on the same click event.
To prevent request from being cancelled, JavaScript event.preventDefault(); have to be called:
<script>
$("#call_ajax").on("click", function(event){
event.preventDefault();
$.ajax({
...
});
});
</script>
NB: Make sure you don't have any wrapping form elements.
I had a similar issue where my button with onclick={} was wrapped in a form element. When clicking the button the form is also submitted, and that messed it all up...
Another thing to look out for could be the AdBlock extension, or extensions in general.
But "a lot" of people have AdBlock....
To rule out extension(s) open a new tab in incognito making sure that "allow in incognito is off" for the extention(s) you want to test.
In my case, I found that it is jquery global timeout settings, a jquery plugin setup global timeout to 500ms, so that when the request exceed 500ms, chrome will cancel the request.
You might want to check the "X-Frame-Options" header tag. If its set to SAMEORIGIN or DENY then the iFrame insertion will be canceled by Chrome (and other browsers) per the spec.
Also, note that some browsers support the ALLOW-FROM setting but Chrome does not.
To resolve this, you will need to remove the "X-Frame-Options" header tag. This could leave you open to clickjacking attacks so you will need to decide what the risks are and how to mitigate them.
Here's what happened to me: the server was returning a malformed "Location" header for a 302 redirect.
Chrome failed to tell me this, of course. I opened the page in firefox, and immediately discovered the problem.
Nice to have multiple tools :)
Another place we've encountered the (canceled) status is in a particular TLS certificate misconfiguration. If a site such as https://www.example.com is misconfigured such that the certificate does not include the www. but is valid for https://example.com, chrome will cancel this request and automatically redirect to the latter site. This is not the case for Firefox.
Currently valid example: https://www.pthree.org/
A cancelled request happened to me when redirecting between secure and non-secure pages on separate domains within an iframe. The redirected request showed in dev tools as a "cancelled" request.
I have a page with an iframe containing a form hosted by my payment gateway. When the form in the iframe was submitted, the payment gateway would redirect back to a URL on my server. The redirect recently stopped working and ended up as a "cancelled" request instead.
It seems that Chrome (I was using Windows 7 Chrome 30.0.1599.101) no longer allowed a redirect within the iframe to go to a non-secure page on a separate domain. To fix it, I just made sure any redirected requests in the iframe were always sent to secure URLs.
When I created a simpler test page with only an iframe, there was a warning in the console (which I had previous missed or maybe didn't show up):
[Blocked] The page at https://mydomain.com/Payment/EnterDetails ran insecure content from http://mydomain.com/Payment/Success
The redirect turned into a cancelled request in Chrome on PC, Mac and Android. I don't know if it is specific to my website setup (SagePay Low Profile) or if something has changed in Chrome.
Chrome Version 33.0.1750.154 m consistently cancels image loads if I am using the Mobile Emulation pointed at my localhost; specifically with User Agent spoofing on (vs. just Screen settings).
When I turn User Agent spoofing off; image requests aren't canceled, I see the images.
I still don't understand why; in the former case, where the request is cancelled the Request Headers (CAUTION: Provisional headers are shown) have only
Accept
Cache-Control
Pragma
Referer
User-Agent
In the latter case, all of those plus others like:
Cookie
Connection
Host
Accept-Encoding
Accept-Language
Shrug
I got this error in Chrome when I redirected via JavaScript:
<script>
window.location.href = "devhost:88/somepage";
</script>
As you see I forgot the 'http://'. After I added it, it worked.
Here is another case of request being canceled by chrome, which I just encountered, which is not covered by any of answers up there.
In a nutshell
Self-signed certificate not being trusted on my android phone.
Details
We are in development/debug phase. The url is pointing to a self-signed host. The code is like:
location.href = 'https://some.host.com/some/path'
Chrome just canceled the request silently, leaving no clue for newbie to web development like myself to fix the issue. Once I downloaded and installed the certificate using the android phone the issue is gone.
If you use axios it can help you
// change timeout delay:
instance.defaults.timeout = 2500;
https://github.com/axios/axios#config-order-of-precedence
For my case, I had an anchor with click event like
<a href="" onclick="somemethod($index, hour, $event)">
Inside click event I had some network call, Chrome cancelling the request. The anchor has href with "" means, it reloads the page and the same time it has click event with network call that gets cancelled. Whenever i replace the href with void like
<a href="javascript:void(0)" onclick="somemethod($index, hour, $event)">
The problem went away!
If you make use of some Observable-based HTTP requests like those built-in in Angular (2+), then the HTTP request can be canceled when observable gets canceled (common thing when you're using RxJS 6 switchMap operator to combine the streams). In most cases it's enough to use mergeMap operator instead, if you want the request to complete.
I had faced the same issue, somewhere deep in our code we had this pseudocode:
create an iframe
onload of iframe submit a form
After 2 seconds, remove the iframe
thus, when the server takes more than 2 seconds to respond the iframe to which the server was writing the response to, was removed, but the response was still to be written , but there was no iframe to write , thus chrome cancelled the request, thus to avoid this I made sure that the iframe is removed only after the response is over, or you can change the target to "_blank".
Thus one of the reason is:
when the resource(iframe in my case) that you are writing something in, is removed or deleted before you stop writing to it, the request will be cancelled
I have embedded all types of font as well as woff, woff2, ttf when I embed a web font in style sheet. Recently I noticed that Chrome cancels request to ttf and woff when woff2 is present. I use Chrome version 66.0.3359.181 right now but I am not sure when Chrome started canceling of extra font types.
We had this problem having tag <button> in the form, that was supposed to send ajax request from js. But this request was canceled, due to browser, that sends form automatically on any click on button inside the form.
So if you realy want to use button instead of regular div or span on the page, and you want to send form throw js - you should setup a listener with preventDefault function.
e.g.
$('button').on('click', function(e){
e.preventDefault();
//do ajax
$.ajax({
...
});
})
I had the exact same thing with two CSS files that were stored in another folder outside my main css folder. I'm using Expression Engine and found that the issue was in the rules in my htaccess file. I just added the folder to one of my conditions and it fixed it. Here's an example:
RewriteCond %{REQUEST_URI} !(images|css|js|new_folder|favicon.ico)
So it might be worth you checking your htaccess file for any potential conflicts
happened to me the same when calling a. js file with $. ajax, and make an ajax request, what I did was call normally.
In my case the code to show e-mail client window caused Chrome to stop loading images:
document.location.href = mailToLink;
moving it to $(window).load(function () {...}) instead of $(function () {...}) helped.
In can this helps anybody I came across the cancelled status when I left out the return false; in the form submit. This caused the ajax send to be immediately followed by the submit action, which overwrote the current page. The code is shown below, with the important return false at the end.
$('form').submit(function() {
$.validator.unobtrusive.parse($('form'));
var data = $('form').serialize();
data.__RequestVerificationToken = $('input[name=__RequestVerificationToken]').val();
if ($('form').valid()) {
$.ajax({
url: this.action,
type: 'POST',
data: data,
success: submitSuccess,
fail: submitFailed
});
}
return false; //needed to stop default form submit action
});
Hope that helps someone.
For anyone coming from LoopbackJS and attempting to use the custom stream method like provided in their chart example. I was getting this error using a PersistedModel, switching to a basic Model fixed my issue of the eventsource status cancelling out.
Again, this is specifically for the loopback api. And since this is a top answer and top on google i figured i'de throw this in the mix of answers.
For me 'canceled' status was because the file did not exist. Strange why chrome does not show 404.
It was as simple as an incorrect path for me. I would suggest the first step in debugging would be to see if you can load the file independently of ajax etc.
The requests might have been blocked by a tracking protection plugin.
It happened to me when loading 300 images as background images. I'm guessing once first one timed out, it cancelled all the rest, or reached max concurrent request. need to implement a 5-at-a-time
One the reasons could be that the XMLHttpRequest.abort() was called somewhere in the code, in this case, the request will have the cancelled status in the Chrome Developer tools Network tab.
In my case, it started coming after chrome 76 update.
Due to some issue in my JS code, window.location was getting updated multiple times which resulted in canceling previous request.
Although the issue was present from before, chrome started cancelling request after update to version 76.
I had the same issue when updating a record. Inside the save() i was prepping the rawdata taken from the form to match the database format (doing a lot of mapping of enums values, etc), and this intermittently cancels the put request. i resolved it by taking out the data prepping from the save() and creating a dedicated dataPrep() method out of it. I turned this dataPrep into async and await all the memory intensive data conversion. I then return the prepped data to the save() method that i could use in the http put client. I made sure i await on dataPrep() before calling the put method:
await dataToUpdate = await dataPrep();
http.put(apiUrl, dataToUpdate);
This solved the intermittent cancelling of request.

How to redirect users when they access the website's view page source?

I am using the code below to redirect users that did not come from google. It can also prevent direct access to that link without going to google. But why does when I view the page source of my domain ( view-source:https://owndomain.com/NMkrujlS ), it does not redirect to example.com? isn't viewing page source a direct access to my domain? How can I fix this?
Thanks
My code:
var ref = document.referrer;
if (ref.match(/^https?:\/\/([^\/]+\.)?google\.com(\/|$)/i)) {
// do nothing
} else {
// redirect
window.location.replace("https://example.com" + window.location.pathname);
}
The example you linked in the comments of your original question uses a header-based redirect, which is why when you point your instance of Chrome to view-source:rshrt.com/getlink/YCy, it redirects you to the target page. This is in line with how browsers are expected to handle header-based redirects. This fact is confirmed if you open your developer tools' Network tab and inspect the requests that your browser sends to the target site, which show the rshrt.com page redirecting with a 301 Moved Permanently status code (along with the respective Location header, which points to the target page):
In your own example, you're performing a redirect using JavaScript. This JavaScript isn't executed/interpreted by the browser when using view-source. As such, the redirection never happens.
If you'd like this to function moreso like the site you've given as an example, you'll have to configure these redirection rules at a server level to correctly return a 301 or 302 status code (as well as the appropriate Location header), instead of on the client level using JavaScript. How specifically you would accomplish that is entirely dependent on the stack your server runs, and is arguably outside the current scope of the question as you've posed it.

postMessage giving "Blocked frame" error, but only in Safari

I am using postMessage to share data between https://www.example.com (Which I'll call mainSite) and https://subdomain.example.com (which I'll call subSite)
subSite has an iframe to mainSite,
subSite's code looks something like:
//set the src of the iframe
$("#main-site-iframe").attr("src", "https://www.example.com");
//wait for the main site page to open
$("#main-site-iframe")[0].onload = () => {
//my page posts a message to their site
$("#my-iframe")[0].contentWindow.postMessage("messagePlox", "https://www.example.com");
};
//wait for the iframe to message back
window.addEventListener('message', iframeResponse, false);
function iframeResponse(e) {
//make sure the request is from the correct site
if(e.origin == 'https://www.example.com')
{
//Got the data
console.log(e.data);
}
}
mainSite looks like this:
//listen for the subdomain to make a request
window.addEventListener('message', subdomainRequest, false);
function subdomainRequest(e) {
//make sure the request is from the correct subdomain
if(e.origin == 'https://subdomain.example.com')
{
//respond with the data
e.source.postMessage("We got you", e.origin);
}
}
The problem with the above is that it works in every browser EXCEPT Safari which refuses it and says:
Blocked a frame with origin "https://www.example.com" from accessing a frame with origin "https://subdomain.example.com". Protocols, domains, and ports must match.
Which seems to imply the response back is breaking since mainSite is trying to "access" subSite.
Does anyone know why this would only happen in Safari and not in Firefox or Chrome?
Two-way cross-domain iFrame communication is usually blocked in Safari/Opera. The primary way around this is using a gateway that the parent and child both agree on... but they cannot using IPC use network-less messages to communicate bidirectionally. Alternatively, There are some exceptions that are closely guarded by the Nitro JS engine team, it appears if you have a large iFrame and the user is interacting with it, the messages from the parent will go through, and vise versa.
Messages that come from the parent get handled as if they are in a SW... that is to say don't expect things to work normally in the handler... test a lot. My promise resolve function for instance, can't be called from a message handling function for some reason... Which means I have to check to see if the function has been called in a time out, making things, painfully slow.
If you just need to show a success message from the child, you could do this:
parent.sendSuccessMsg();
function sendSuccessMsg(){
document.getElementById('iframeID').src="http://example.com/?successData=123";
}
Otherwise, you can use websockets with a gateway to mingle cross-domain. There seems to be some sort of undocumented exception if you load the iFrame twice, and the message is sent early on iframe load.
Source: https://benohead.com/blog/2015/12/07/cross-document-communication-with-iframes/
Bug/Failsafe Discovery: how to send cross domain post message in safari?

Opening a new window that needs to make ajax calls to another domain

Background
We have two web applications hosted on different sub-domains. Application 1 is an internal admin system. Application 2 is a helpdesk system.
We can modify the source code of Application 1 but we have no access to modify Application 2.
The Goal
To display a link against an order in Application 1 that will open a new window, the URL of which is that of a ticket in Application 2.
The idea being that our staff can see that an order has a helpdesk ticket raised against it and simply needs to click a link on the order to view the ticket and reply to it.
The problem
Regardless of how I open the new window (window.open, target="_blank", etc.) the ticket in the new window is unable to make any ajax requests back to the helpdesk system where it is hosted.
The URL of the new window is part of Application 2.
In Google dev tools it tells me "The frame requesting access has a protocol of "http", the frame being accessed has a protocol of "https". Protocols must match." even when I open it using _blank.
If I go to the exact same URL manually everything works... but this doesn't help when I need it to work from the link.
Is there any way to achieve the above?
If not, is there any way I can open a new window that is "detached" from the window that opened it so that same origin policy no longer applies?
Edit 2014-03-28 10:23
I have no access to App2's code at all. I cannot make any changes to App2. Any answer must take this into account.
I am trying to open a new window from my application (App1) where the target URL of that window is a page in App2. That page inside App2 then needs to be able to use ajax to communicate with other areas of App2. This is where the problem lies. Because App1 opened the window the same origin policy is preventing that window from making it's ajax requests.
I suspect that JavaScript on the second (helpdesk) app is trying to access the first app via window.opener (which could lead to the cross-origin error you're seeing) and subsequent JavaScript (fetching stuff via AJAX) is then not getting executed. You can probably narrow things down by setting appropriate breakpoints in the second app.
If this is the cause and you can't modify the source for the helpdesk app, how about going to a URL in the internal domain that would then redirect to the help desk? The redirect should cause the window.opener property to become null (same as manually typing in the URL).
Assuming https://admin.mydomain.co.uk and http://helpdesk.mydomain.co.uk, clicking on the "Help Ticket" link would go to a URL in the internal app, e.g. https://admin.mydomain.co.uk/getHelp?ticketId, which would respond with a 301 response and an appropriate Location: http://helpdesk.domain.uk/help/ticketId header taking the user to the actual helpdesk URL.
You could use a proxy server or iframe proxying.
Use the following url //app2.mydomain.co.uk without the http or https.
It's not only a cross domain problem but a protocol issue :
You can't embed https into http page without this warning.
Consider using iframe inside your App1 :
<iframe src="https://app2.mydomain.co.uk" ></iframe>
Or maybe you can use CORS to access data between your two domains ( but i think it's not the point, you want the whole App2 page, isn't it ? )
Edit : By re-reading your question, i'm pretty sure of two thing :
You're not looking at the right direction. You say App2 don't use SSL, and that obviously false when Chrome say "Protocols must match"
It's not a "attach" or "detached" problem. If you put a link (blank or not) in a page, it can be load the new page without any problem, nor link with the referal page.
So my guess is : Your are calling App2 without SSL ( no https), BUT inside the App2, there is some https involved ( certainly some ajax query). So here is the problem : When you open the page without https, it's seem to load, but when the first https Ajax fires, it fail.
Try using https when calling your App2 url, and give us the result
My solution is this: in Application 1 you create a method your method that calling Application 2 on the server side, then you can use AJAX calling your method which will return result of Application 2.

Authenticate a facebook user in a Firefox plug-in

I'm trying to write a Firefox plug-in that accesses data from facebook.
Now I'm not sure how to get an access token.
I tried to implement the client side flow for desktop apps (with the fixed redirect uri), but the big problem I encounter there, is that JavaScript doesn't allow me to wait for the redirect to happen.
Any idea how this could be done?
As far as I understood it, because I don't have a webpage, the JavaScript API doesn't help much, right?
I guess that you are opening https://www.facebook.com/dialog/oauth in a browser tab to let the user log in and give you access. You don't need to pass a working redirect URL here, you can rather use something that will definitely not work, like http://my.extension.local/. Then you only need to detect when the tab gets redirected to that URL. If you have a classic extension, you register a progress listener on the <browser> element of that tab and look at onLocationChange() calls - once you see a location starting with http://my.extension.local/ you can cancel the request and close the tab, the necessary data is in the URL. If you use the Add-on SDK you can attach a ready event listener to the tab, something along these lines:
var tabs = require("tabs");
tabs.open({
url: "https://www.facebook.com/dialog/oauth?...",
inBackground: false,
onReady: function(tab)
{
if (tab.url.indexOf("http://my.extension.local/") == 0)
{
...
}
}
});

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