CSRF/Ajax/jQuery example could break other site JS

[LukeMaurer]

The example given for setting up jQuery to pass the CSRF token in Ajax requests (​http://docs.djangoproject.com/en/1.2/ref/contrib/csrf/#ajax) has a problem: If the site already uses $.ajaxSetup({beforeSend: ...}) for other processing, this code will clobber that other handler (or vice versa).

The ​jQuery docs suggest using $.ajaxSend() and friends for setting up global callbacks, rather than $.ajaxSetup(), I suspect for this reason.

At any rate, using jQuery's suggestion would make the example look like:

$.ajaxSend(function(event, xhr, settings) {
    function getCookie(name) {
        var cookieValue = null;
        if (document.cookie && document.cookie != '') {
            var cookies = document.cookie.split(';');
            for (var i = 0; i < cookies.length; i++) {
                var cookie = jQuery.trim(cookies[i]);
                // Does this cookie string begin with the name we want?
                if (cookie.substring(0, name.length + 1) == (name + '=')) {
                    cookieValue = decodeURIComponent(cookie.substring(name.length + 1));
                    break;
                }
            }
        }
        return cookieValue;
    }
    if (!(/^http:.*/.test(settings.url) || /^https:.*/.test(settings.url))) {
        // Only send the token to relative URLs i.e. locally.
        xhr.setRequestHeader("X-CSRFToken", getCookie('csrftoken'));
    }
});

(where only the outer function call and the signature of the callback have changed)

[Luke Plant]

I was aware of that problem with beforeSend, but I hadn't realised that you could actually alter the XHR request in ajaxSend. This is potentially fragile (the docs only give examples of reading the XHR object, not altering it), but it seems unlikely to break, so I agree that we should change this.

[Luke Plant]

In [15515]:

Fixed #15284 - improved example jQuery code for adding X-CSRF-Token

Using the ajaxSend event is better than beforeSend, because the beforeSend
callback can have only one value, which makes it painful if it is needed by
multiple bits of javascript.

Thanks to LukeMaurer for report and initial patch.

[Luke Plant]

In [15517]:

[1.2.X] Fixed #15284 - improved example jQuery code for adding X-CSRF-Token

Using the ajaxSend event is better than beforeSend, because the beforeSend
callback can have only one value, which makes it painful if it is needed by
multiple bits of javascript.

Thanks to LukeMaurer for report and initial patch.

Backport of [15515] from trunk.

[Luke Plant]

In [15518]:

[1.1.X] Fixed #15284 - improved example jQuery code for adding X-CSRF-Token

Using the ajaxSend event is better than beforeSend, because the beforeSend
callback can have only one value, which makes it painful if it is needed by
multiple bits of javascript.

Thanks to LukeMaurer for report and initial patch.

Backport of [15515] from trunk.

This is backported to 1.1.X because it really belongs with security patch [15466]

[Matthew Schinckel]

The example code is broken: $.ajaxSend does not exist.

I use instead:

$(document).ajaxSetup(…)

[Jacob]

Milestone 1.3 deleted