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

• django: http://djangoproject.com/
• bleach: http://github.com/jsocol/bleach

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 0.1.4

• 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 []