recaptcha_v2.py

import json
import logging
from django.conf import settings
from django import forms
from django.utils.safestring import mark_safe
from django.utils.translation import ugettext_lazy as _
from six.moves.urllib.request import urlopen
from six.moves.urllib.parse import urlencode
from six.moves.urllib.error import URLError

class gReCaptcha(forms.widgets.Widget):
    recaptcha_response_name = 'g-recaptcha-response'
    recaptcha_html = (u'<script src="https://www.google.com/recaptcha/api.js" async defer></script>'
                      '<div class="g-recaptcha" data-sitekey="{key}"></div>')

    def render(self, name, value, attrs=None):
        return mark_safe(self.recaptcha_html.format(key=settings.RECAPTCHA_V2_PUBLIC_KEY))

    def value_from_datadict(self, data, files, name):
        return data.get(self.recaptcha_response_name, None)


class gReCaptchaField(forms.CharField):
    default_error_messages = {
        'captcha_invalid': _(u'Invalid captcha'),
        'connection_error': _(u"Can't connect to reCAPTCHA server"),
    }
    verify_url = 'https://www.google.com/recaptcha/api/siteverify?{}'

    def __init__(self, *args, **kwargs):
        self.widget = gReCaptcha
        self.required = True
        super(gReCaptchaField, self).__init__(*args, **kwargs)

    def clean(self, value):
        super(gReCaptchaField, self).clean(value)

        data = urlencode([('secret', settings.RECAPTCHA_V2_PRIVATE_KEY), ('response', value)])
        try:
            response = urlopen(self.verify_url.format(data)).read()
        except URLError:
            logger.exception("Can't connect to reCAPTCHA server to verify user response")
            raise forms.ValidationError(self.error_messages['connection_error'])

        check_captcha = json.loads(response.decode('utf-8'))

        if not check_captcha['success']:
            raise forms.ValidationError(self.error_messages['captcha_invalid'])
        return value