gistfile1.py

import functools

def plivo_validate(func):
    """validate a request from plivo

    returns true if the request passes validation, false if not
    """
    @functools.wraps(func)
    def wrapper(handler, *args, **kwargs):
        # compute full URL without query elements
        source = "{0}://{1}{2}".format(
            handler.request.protocol,
            handler.request.host,
            handler.request.path)
        # append GET query string sorted by key to the uri
        plargs = handler.request.arguments.iteritems()
        # POST Is treated differently
        if handler.request.method == 'POST':
            plargs = handler.request.body_arguments.iteritems()
            source = handler.request.full_url()
        # compute signature and compare signatures
        source += "".join(sorted((arg[0] + arg[1][0] for arg in plargs)))
        digest = hmac.new(handler.plivo_token, source, hashlib.sha1)
        signed = handler.request.headers.get('X-Plivo-Signature')
        # validate if signed is None, return None
        if base64.encodestring(digest.digest()).strip() != signed:
            # Send a not found error
            raise HTTPError(404)
        # invoke func
        return func(handler, *args, **kwargs)
    return wrapper