In this guide we'll cover how to secure your Django application by validating incoming requests to your Twilio webhooks are, in fact, from Twilio.
With a few lines of code, we'll write a custom decorator for our Django project that uses the Twilio Python SDK's validator utility. We can then use that decorator on our Django views which accept Twilio webhooks to confirm that incoming requests genuinely originated from Twilio.
Let's get started!
The Twilio Python SDK includes a RequestValidator class we can use to validate incoming requests.
We could include our request validation code as part of our Django views, but this is a perfect opportunity to write a Python decorator. This way we can reuse our validation logic across all our views which accept incoming requests from Twilio.
Confirm incoming requests to your Django views are genuine with this custom decorator.
_29from django.http import HttpResponse, HttpResponseForbidden_29from functools import wraps_29from twilio import twiml_29from twilio.request_validator import RequestValidator_29_29import os_29_29_29def validate_twilio_request(f):_29 """Validates that incoming requests genuinely originated from Twilio"""_29 @wraps(f)_29 def decorated_function(request, *args, **kwargs):_29 # Create an instance of the RequestValidator class_29 validator = RequestValidator(os.environ.get('TWILIO_AUTH_TOKEN'))_29_29 # Validate the request using its URL, POST data,_29 # and X-TWILIO-SIGNATURE header_29 request_valid = validator.validate(_29 request.build_absolute_uri(),_29 request.POST,_29 request.META.get('HTTP_X_TWILIO_SIGNATURE', ''))_29_29 # Continue processing the request if it's valid, return a 403 error if_29 # it's not_29 if request_valid:_29 return f(request, *args, **kwargs)_29 else:_29 return HttpResponseForbidden()_29 return decorated_function
To validate an incoming request genuinely originated from Twilio, we first need to create an instance of the RequestValidator class using our Twilio auth token. After that we call its validate method, passing in the request's URL, payload, and the value of the request's X-TWILIO-SIGNATURE header.
That method will return True if the request is valid or False if it isn't. Our decorator then either continues processing the view or returns a 403 HTTP response for inauthentic requests.
Now we're ready to apply our decorator to any view in our Django project that handles incoming requests from Twilio.
Apply a custom Twilio request validation decorator to a Django view used for Twilio webhooks.
_43from django.http import HttpResponse_43from django.views.decorators.csrf import csrf_exempt_43from django.views.decorators.http import require_POST_43from twilio.twiml.voice_response import VoiceResponse, MessagingResponse_43_43_43@require_POST_43@csrf_exempt_43@validate_twilio_request_43def incoming_call(request):_43 """Twilio Voice URL - receives incoming calls from Twilio"""_43 # Create a new TwiML response_43 resp = VoiceResponse()_43_43 # <Say> a message to the caller_43 from_number = request.POST['From']_43 body = """_43 Thanks for calling!_43_43 Your phone number is {0}. I got your call because of Twilio's webhook._43_43 Goodbye!""".format(' '.join(from_number))_43 resp.say(body)_43_43 # Return the TwiML_43 return HttpResponse(resp)_43_43_43@require_POST_43@csrf_exempt_43@validate_twilio_request_43def incoming_message(request):_43 """Twilio Messaging URL - receives incoming messages from Twilio"""_43 # Create a new TwiML response_43 resp = MessagingResponse()_43_43 # <Message> a text back to the person who texted us_43 body = "Your text to me was {0} characters long. Webhooks are neat :)" \_43 .format(len(request.POST['Body']))_43 resp.message(body)_43_43 # Return the TwiML_43 return HttpResponse(resp)
To use the decorator with an existing view, just put @validate_twilio_request above the view's definition. In this sample application, we use our decorator with two views: one that handles incoming phone calls and another that handles incoming text messages.
Note: If your Twilio webhook URLs start with https:// instead of http://, your request validator may fail locally when you use Ngrok or in production if your stack terminates SSL connections upstream from your app. This is because the request URL that your Django application sees does not match the URL Twilio used to reach your application.
To fix this for local development with Ngrok, use http:// for your webhook instead of https://. To fix this in your production app, your decorator will need to reconstruct the request's original URL using request headers like X-Original-Host and X-Forwarded-Proto, if available.
If you write tests for your Django views those tests may fail for views where you use your Twilio request validation decorator. Any requests your test suite sends to those views will fail the decorator's validation check.
To fix this problem we recommend adding an extra check in your decorator, like so, telling it to only reject incoming requests if your app is running in production.
Use this version of the custom Django decorator if you test your Django views.
_29from django.conf import settings_29from django.http import HttpResponseForbidden_29from functools import wraps_29from twilio.request_validator import RequestValidator_29_29import os_29_29_29def validate_twilio_request(f):_29 """Validates that incoming requests genuinely originated from Twilio"""_29 @wraps(f)_29 def decorated_function(request, *args, **kwargs):_29 # Create an instance of the RequestValidator class_29 validator = RequestValidator(os.environ.get('TWILIO_AUTH_TOKEN'))_29_29 # Validate the request using its URL, POST data,_29 # and X-TWILIO-SIGNATURE header_29 request_valid = validator.validate(_29 request.build_absolute_uri(),_29 request.POST,_29 request.META.get('HTTP_X_TWILIO_SIGNATURE', ''))_29_29 # Continue processing the request if it's valid (or if DEBUG is True)_29 # and return a 403 error if it's not_29 if request_valid or settings.DEBUG:_29 return f(request, *args, **kwargs)_29 else:_29 return HttpResponseForbidden()_29 return decorated_function
Validating requests to your Twilio webhooks is a great first step for securing your Twilio application. We recommend reading over our full security documentation for more advice on protecting your app, and the Anti-Fraud Developer's Guide in particular.
To learn more about securing your Django application in general, check out the official Django security docs.