Flask-WTF set time limit on CSRF token

问题

I'm currently using Flask-WTF v0.13.1, i have a few forms on my website, all created including the CSRF token.

For some reasons i have to set a different expiration on each form, so far i could set manually the time_limit value upon creating the csrf token.

I would like to update to the v0.14, according to the changelog time_limit is gone and there is no reference in the docs on how to change it anymore. Looking in the source code i saw that the form has a csrf_time_limit meta parameter.

I tried to set that parameter on my form:

from flask_wtf import FlaskForm

class myForm(FlaskForm):
    class Meta:
        csrf_time_limit = 7200

    content = TextAreaField('content')

Although debugging the csrf.py module i see that the validate_csrf_token of _FlaskFormCSRF is actually never called.

The method validate_csrf is called within the method protect() instead, in this case the meta parameter is never considered.

I don't understand if this is a bug of the package or if i'm missing something.

UPDATE:

Example code:

app.py

from flask import Flask, render_template, request
from flask_wtf.csrf import CSRFProtect
from flask_wtf import FlaskForm
from wtforms import IntegerField

csrf = CSRFProtect()
app = Flask(__name__)
app.config.update(dict(
    SECRET_KEY="super secret key"
))

csrf.init_app(app)

class MyForm(FlaskForm):
    class Meta:
        csrf_time_limit = 1

    id = IntegerField('id')

@app.route("/", methods=['GET', 'POST'])
def test_form_csrf():
    if request.method == 'POST':
        myForm = MyForm(request.form)
        print(myForm.id.data)

    return render_template('test_form.html', myForm= MyForm())

templates/test_form.html

<form method="post" action="/">
    <input type="hidden" name="csrf_token" value="{{ csrf_token() }}" />
    {{ myForm.id }}
    <input type="submit" value="test" />
</form>

requirements.txt

click==6.7
Flask==0.12.2
Flask-WTF==0.14.2
itsdangerous==0.24
Jinja2==2.10
MarkupSafe==1.0
Werkzeug==0.14.1
WTForms==2.1

project structure

app.py
templates
|
--- test_form.html

To run the code,

FLASK_APP=app.py flask run

I also put a debug breakpoint on this line to check the actual value of time_limit, the value is always 3600.

回答1:

Following your changelog link, I looked through the commit and found these lines:

if time_limit is None:
    time_limit = current_app.config.get('WTF_CSRF_TIME_LIMIT', 3600)

Setting app.config['WTF_CSRF_TIME_LIMIT'] to some shorter value seems to work. I have set it to 30 seconds with app.config['WTF_CSRF_TIME_LIMIT'] = 30 and the form expired after that amount of time, but I have not tried a longer value than the default.

I am not sure if you can change an app.config value on the fly in order to hack your way around not being able to set an expiration per form.

来源：https://stackoverflow.com/questions/48640652/flask-wtf-set-time-limit-on-csrf-token

标签

python

Flask

csrf

flask-wtforms