Synnefo

    Utility method to validate that provided url is safe to be used as the

    redirect location of an http redirect response. The method parses the

    provided url and identifies if it conforms CORS against provided domain

    AND url scheme matches any of the schemes in `allowed_schemes` parameter.

    If verirication succeeds sanitized safe url is returned so you must use

    the method's response in the response location header and not the

    originally provided url. If verification fails the method returns None.

    >>> print restrict_next('pithos.okeanos.grnet.gr/im/feedback',

    ...                     '.okeanos.grnet.gr')

    >>> print restrict_next('https://pithos.okeanos.grnet.gr/im/feedback',

    ...                     '.okeanos.grnet.gr')

    >>> print restrict_next('pithos://127.0.0.1', '.okeanos.grnet.gr',

    ...                     allowed_schemes=('pithos'))

    None

    >>> print restrict_next('pithos://127.0.0.1', '127.0.0.1',

    ...                     allowed_schemes=('pithos'))

    pithos://127.0.0.1

    >>> print restrict_next('node1.example.com', allowed_schemes=('pithos',))

    None

    >>> print restrict_next('pithos://localhost', 'localhost',

    ...                     allowed_schemes=('pithos',))

    pithos://localhost

        return None

    if not domain and not allowed_schemes:

    if domain:

        if not parts.netloc:

            return url

        if parts.netloc.endswith(domain):

            return url

        else:

            return None

    if allowed_schemes:

        if parts.scheme in allowed_schemes:

            return url

    return None