Flask-WTForms provides CSRF protection. It works great when using normal HTML forms, but the process is less clear when using AJAX. I have a file upload in my form, and I split the process in two with AJAX: the file goes to the upload
endpoint while the rest of the form goes to the submit
endpoint. Since the file is posted with AJAX, it doesn't get a CSRF token, but I want to protect the upload
endpoint from attacks. How can I generate a CSRF token when using AJAX?
@app.route('/submit', methods=["GET","POST"])
@login_required
def submit():
form = MyForm()
if request.method == "POST" and form.validate():
# success, csrf checks out and data is validated
# do stuff
csrf_for_uploads = # generate csrf?
return render_template('some_form.html', form=form, csrf_for_uploads=csrf_for_uploads)
@app.route('/upload', methods=["POST"])
@login_required
def upload():
myfile = request.files['file']
# How do I verify CSRF now?
The documentation speaks a bit about implementing CSRF protection with regards to AJAX.
You can enable the module:
from flask_wtf.csrf import CsrfProtect
CsrfProtect(app)
and then use this in your AJAX POST call:
<meta name="csrf-token" content="{{ csrf_token() }}">
var csrftoken = $('meta[name=csrf-token]').attr('content')
$.ajaxSetup({
beforeSend: function(xhr, settings) {
if (!/^(GET|HEAD|OPTIONS|TRACE)$/i.test(settings.type) && !this.crossDomain) {
xhr.setRequestHeader("X-CSRFToken", csrftoken)
}
}
})
Hope this helps!
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