javascript cross-domain issue - javascript

I am building a small widget that I am giving to users to embed in their websites and blogs. Now the widget loads a javascript file in the page where it is embedded from my server, which in turn puts an xmlhttp request back to my server to obtain data. Due to security reasons this request is being blocked when placed on other server (except my server). I need a solution to this.
I have searched a lot for a solution.
I am sure I cannot use the proxy solution here as the domains on which the script will be running is not controlled by me.
Also, I cannot use iframe due to Search engines.
What could be a possible solution?
Thanks,
happyhardik

To my knowledge, using JSONP is the only way to do this.
Also, I cannot use iframe due to Search engines.
This I don't understand, though: If your widget is JavaScript driven, it won't turn up in any search engines anyway, will it?

This is pretty much a duplicate of any number of related queries. e.g.
Cross Domain Scripting Issues & JSONP
Basically you want to use JSONP.
EDIT: I see Pekka has already said this.

Browsers do not support cross domain ajax requests due same origin policy. You can check out this javascript library: ACD.

Related

Xpath of element on another website/cross domain

I want to get the XPATH of an element on a website (my own domain), which I got it using JavaScript code as mentioned in this answer.
Now what I want to click on button which will open a url (cross domain) window and when user click on an element on that window it's XPATH is captured.
I tried doing the same using iframe with no luck.
Now my question is there a way to get the XPATH of an element of another website/ Cross domain?
Sorry this is not possible without cooperation from the other (x-domain) site. Browsers are designed not to allow access to the DOM of x-domain documents (iframe included) for security reasons.
If you had cooperation from the other site, they could load your javascript file and then use postmessage to pass the xpath to the original page.
Other options would be to create a bookmarklet users could use on the other page, or a browser extension (Chrome and FF are pretty easy to develop for)... depends on your use case.
From your comments, I've gathered that you want to capture information from another website that doesn't have Access-Control-Allow-Origin headers that include your domain (e.g. the other site does not have CORS enabled). This is not possible to do cross-domain and client-side due to the Same-Origin Policy implemented in most modern browsers. The Same-Origin Policy prevents any resources on your site from interacting with resources on any other site (unless the other site explicitly shares them with your site using the Access-Control-Allow-Origin HTTP header).
If you want to get information about another site from your site, there is no way around using server-side code. A simple solution would be to implement a server-side proxy that re-serves off-site pages from your own origin, so the Same-Origin Policy will not be violated.
You may get the data using jQuery's load function, and append it to your page.
From there, the DOM nodes from your external page should be accessible for your processing.
$('#where-you-want').load('//example.com body', function() {
console.log($('#where-you-want'))
// process the DOM node under `#where-you-want` here with XPath.
})
You can see this in action here: http://jsfiddle.net/xsvkdugo/
P.S.: this assumes you are working with a CORS-enabled site.

API for cross-site-scripting?

Is there any way to send HTTP requests to non-cooperating websites with javascript? I'm aware that this is forbidden because of the same origin policy, but is there any way to do it, including experimental APIs, Java applets, Flash, browser extensions, hidden settings, special certificates etc.? It's fine if the user explicitly has to grant my page permissions to access the other site, in fact that would be very reasonable.
Background: I'm trying to do a kind of mash-up by scraping several site's html, and I would like to do it from the user's IP address and not from my server.
Just a thought - If any of those websites use JQuery - this tunneling mehod might work:
http://benv.ca/2011/3/7/subdomain-tunneling-with-jquery-and-document-domain/
Create an iframe in a page on your site, load the page from the other website into it, replace your page's jquery ajax object with the one from the iframe - and you could be good to go!
Let me know if you try it :)

How do I counter iframe security problems?

I heard there are many security issues that could arise when you use iframes. I already handle XSS, what else should I do to make sure no problems happen?
I came across some JS codes where you use top.window, but my concern is that any client-side code is not reliable, anything else I can do from the server side? (I am currently using php, but would be awesome if the solution is generic)
UPDATE: to make things clearer, I am actually using an iframe, its just because I don't want the headers, menues etc.. to be refreshed every time. So I am trying to find a way to use iframe without falling into security problems.
You could set the X-FRAME-OPTIONS header to deny. This will let the browsers know that if the resource is loaded via iframe then don't display.
You can read more about this & configuring the server to send this header # MDN. Also, you in PHP you can use
header("X-FRAME-OPTIONS: DENY")

Java script in IFRAME security issues

On the website http://imaginaryman-test.blogspot.com/ the typewriter is inside of an IFAME . Everything works correctly on all browsers when you go to the site directly http://castedspell.com/mark/ but when viewing the version embeded in an IFRAME it does not work on IE and throws errors in Chrome.
Unsafe JavaScript attempt to access frame with URL http://imaginaryman-test.blogspot.com/ from frame with URL http://castedspell.com/mark/. Domains, protocols and ports must match.
This is the source code for the embedded IFRAME
https://github.com/totheleftpanda/typeWrite/tree/master/mark
I understand that this is a security problem but I don`t know how to fix it and can not find any material that would help me solve the issue.
The easiest method is to set a PHP (or any server language) proxy that just gets the content of the page from the other domain and outputs it. The only real drawback is that the cookies of the client for the remote domain aren't sent.
Take a look at http://benalman.com/projects/jquery-postmessage-plugin/. This is a jquery plugin that sends message between the two frames. The two frames do not need to be on the same domain. But you do need to access both pages to be able modify them. I also wrote a post here that answers communication between iframes. How to capture clicks from iframe on another domain?
Your only chance is something like easyXDM. (or do it manually using the hash, but would prefer easyXDM)
See the SO answer: Cross-domain hash change communication
eg. if you wanna call a method:
http://easyxdm.net/wp/2010/03/17/remote-procedure-calls-rpc/
EDIT:
If I try your demo in firefox I don't get the "Unsafe JavaScript attempt to access" error at all. But in Chrome it's thrown many times.
You have so much other code in your example that I'm not even sure that your code causes the problem. You should do a very limited/basic test to see if your flash-communication works, without all those other javascripts.
I have had similar issues with this before. Basically if you have an iframe that contains a page from a domain that differs from the main page's domain, javascript will not be able to cross the boundaries between them. Javascript within the iframe will be able to talk within the iframe, javascript in the main page will be able to talk within the main page, but they will not be able to talk to each other.
This is a security issue that aims to stop cross-site scripting attacks. There are a number of hacks that you can put in place to get around this problem but they are all (or at least the ones I know of) rather hairy.
Here are some questions that you should answer before trying to go further:
1) What exactly are you trying to do between the pages using javascript?
2) Do you have access to the source of both pages?
It may be waaay simpler than the above answers. It looks like this function:
function playSound(){
swf.playSound();
}
Is written in the DOM timeline before swf is actually assigned to the swfObject in the function below it.
I would recommend moving that function down further and then retest.

Alternatives to iframe for loading cross-site HTML when using iPhone?

I apologize if this has been asked before. I searched but did not find anything. It is a well-known limitation of AJAX requests (such as jQuery $.get) that they have to be within the same domain for security reasons. And it is a well-known workaround for this problem to use iframes to pull down some arbitrary HTML from another website and then you can inspect the contents of this HTML using javascript which communicates between the iframe and the parent page.
However, this doesn't work on the iPhone. In some tests I have found that iframes in the Safari iPhone browser only show content if it is content from the same site. Otherwise, they show a blank content area.
Is there any way around this? Are there other alternatives to using iframes that would allow me to pull the HTML from a different domain's page into javascript on my page?
Edit:
One answer mentioned JSONP. This doesn't help me because from what I understand JSONP requires support on the server I'm requesting data from, which isn't the case.
That same answer mentioned creating a proxy script on my server and loading data through there. Unfortunately this also doesn't work in my case. The site I'm trying to request data from requires user login. And I don't want my server to have to know the user's credentials. I was hoping to use something client-side so that my app wouldn't have to know the user's credentials at the other site.
I'm prepared to accept that there is no way to accomplish what I want to do on the iPhone. I just wanted to confirm it.
You generally can NOT inspect the contents of an iframe from another domain via JavaScript. The most common answers are to use JSONP or have your original server host a proxy script to retrieve the inner contents for you.
Given your revisions, without modification or support from the secondary site, you are definitely not going to be able to do what you want via the iPhone's browser.
"In some tests I have found that iframes in the Safari iPhone browser only show content if it is content from the same site"
I found the same thing. Is this documented somewhere? Is there a workaround? This sounds like broken web standards to me, and I am wondering if there is a solution.

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