Django HTML Sanitizer

Django HTML Sanitizer provides a set of utilities to easily sanitize/escape/clean HTML inputs in django. This app is built on top of bleach, the excellent Python HTML sanitizer.

Dependencies

Installation

You'll first need to install the package (or download manually from pypi):

pip install django-html_sanitizer

And then add sanitizer to your INSTALLED_APPS in django's settings.py:

INSTALLED_APPS = (
    # other apps
    "sanitizer",
)

Model Usage

Similar to bleach, django sanitizer is a whitelist (only allows specified tags and attributes) based HTML sanitizer. Django sanitizer provides two model fields that automatically sanitizes text values; SanitizedCharField and SanitizedTextField.

These fields accept extra arguments:

allowed_tags: a list of allowed HTML tags
allowed_attributes: a list of allowed HTML attributes, or a dictionary of tag keys with atttribute list for each key
allowed_styles: a list of allowed styles if "style" is one of the allowed attributes
strip: a boolean indicating whether offending tags/attributes should be escaped or stripped

Here's how to use it in django models:

from django.db import models
from sanitizer.models import SanitizedCharField, SanitizedTextField

class MyModel(models.Model):
    # Allow only <a>, <p>, <img> tags and "href" and "src" attributes
    foo = SanitizedCharField(max_length=255, allowed_tags=['a', 'p', 'img'],
                             allowed_attributes=['href', 'src'], strip=False)
    bar = SanitizedTextField(max_length=255, allowed_tags=['a', 'p', 'img'],
                             allowed_attributes=['href', 'src'], strip=False)
    foo2 = SanitizedCharField(max_length=255, allowed_tags=['a', 'p', 'img'],
                             allowed_attributes={'img':['src', 'style']},
                             allowed_styles=['width', 'height'], strip=False)

Form Usage

Using django HTML sanitizer in django forms is very similar to model usage:

from django import forms
from sanitizer.forms import SanitizedCharField

class MyForm(forms.Form):
    # Allow only <a>, <p>, <img> tags and "href" and "src" attributes
    foo = SanitizedCharField(max_length=255, allowed_tags=['a', 'p', 'img'],
                             allowed_attributes=['href', 'src'], strip=False)
    bar = SanitizedCharField(max_length=255, allowed_tags=['a', 'p', 'img'],
                             allowed_attributes=['href', 'src'], strip=False, widget=forms.Textarea)
    foo2 = SanitizedCharField(max_length=255, allowed_tags=['a', 'p', 'img'],
                             allowed_attributes={'img':['src', 'style']},
                             allowed_styles=['width', 'height'], strip=False)

Template Usage

Django sanitizer provides a few differents ways of cleaning HTML in templates.

`escape_html` Template Tag

Example usage:

{% load sanitizer %}
{% escape_html post.content "a, p, img" "href, src, style" "width"%}

Assuming post.content contains the string '<a href ="#" style="width:200px; height="400px">Example</a><script>alert("x")</script>', the above tag will output:

'<a href ="#" style="width:200px;">Example</a>&lt;script&gt;alert("x")&lt;/script&gt;'

On django 1.4 you could also use keyword arguments:

{% escape_html '<a href="">bar</a>' allowed_tags="a,img" allowed_attributes="href,src" allowed_styles="width" %}

`strip_html` Template Tag

Example usage:

{% load sanitizer %}
{% strip_html post.content "a, p, img" "href, src" %}

If post.content contains the string '<a href ="#">Example</a><script>alert("x")</script>', this will give you:

'<a href ="#">Example</a>alert("x")'

`escape_html` Filter

Escapes HTML tags from string based on settings. To use this filter you need to put these variables on settings.py:

SANITIZER_ALLOWED_TAGS - a list of allowed tags (defaults to an empty list)
SANITIZER_ALLOWED_ATTRIBUTES - a list of allowed attributes (defaults to an empty list)
SANITIZER_ALLOWED_STYLES - a list of allowed styles if the style attribute is set (defaults to an empty list)

For example if we have SANITIZER_ALLOWED_TAGS = ['a'], SANITIZER_ALLOWED_ATTRIBUTES = ['href'], SANITIZER_ALLOWED_STYLES = ['width'] in settings.py, doing:

{% load sanitizer %}
{{ post.content|escape_html }}

If post.content contains the string '<a href ="#" style="width:200px; height:400px">Example</a><script>alert("x")</script>', it will give you:

'<a href ="#" style="width=200px;">Example</a>&lt;script&gt;alert("x")&lt;/script&gt;'

`strip_html` Filter

Similar to escape_html filter, except it strips out offending HTML tags.

For example if we have SANITIZER_ALLOWED_TAGS = ['a'], SANITIZER_ALLOWED_ATTRIBUTES = ['href'] in settings.py, doing:

{% load sanitizer %}
{{ post.content|strip_html }}

If post.content contains the string '<a href ="#">Example</a><script>alert("x")</script>', we will get:

'<a href ="#">Example</a>alert("x")'

Changelog

Version 0.1.5

Fixes for smart_unicode and basestring (python 3.x support)

Version 0.1.4

CharField, TextField, strip_html and escape_html now support allowed_styles (thanks cltrudeau,
Added an example of template tag usage using kwargs now that Django 1.4 is out

Version 0.1.2

allowed_tags and allowed_attributes in CharField and TextField now default to []

ui/django-html_sanitizer