Opened 14 years ago

Closed 14 years ago

Last modified 13 years ago

#15284 closed (fixed)

CSRF/Ajax/jQuery example could break other site JS

Reported by: LukeMaurer Owned by: nobody
Component: Documentation Version: 1.2
Severity: Keywords:
Cc: Triage Stage: Accepted
Has patch: no Needs documentation: no
Needs tests: no Patch needs improvement: no
Easy pickings: no UI/UX: no

Description

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)

Change History (7)

comment:1 by Gabriel Hurley, 14 years ago

milestone: 1.3
Triage Stage: UnreviewedAccepted

comment:2 by Luke Plant, 14 years ago

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.

comment:3 by Luke Plant, 14 years ago

Resolution: fixed
Status: newclosed

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.

comment:4 by Luke Plant, 14 years ago

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.

comment:5 by Luke Plant, 14 years ago

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]

comment:6 by Matthew Schinckel, 14 years ago

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

I use instead:

$(document).ajaxSetup(…)

[Then looked at actual documentation. *headdesk*]

Last edited 14 years ago by Matthew Schinckel (previous) (diff)

comment:7 by Jacob, 13 years ago

milestone: 1.3

Milestone 1.3 deleted

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