# Copyright (c) 2014, Fortylines LLC
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#
#   * Redistributions of source code must retain the above copyright notice,
#     this list of conditions and the following disclaimer.
#   * Redistributions in binary form must reproduce the above copyright notice,
#     this list of conditions and the following disclaimer in the documentation
#     and/or other materials provided with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
# THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
# PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
# EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
# PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
# OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
# WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
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# ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

import urlparse

from django.conf import settings
from django.http.request import split_domain_port, validate_host

def validate_redirect_url(next_url):
    """
    Returns the next_url path if next_url matches allowed hosts.
    """
    if not next_url:
        return None
    parts = urlparse.urlparse(next_url)
    if parts.netloc:
        domain, port = split_domain_port(parts.netloc)
        allowed_hosts = ['*'] if settings.DEBUG else settings.ALLOWED_HOSTS
        if not (domain and validate_host(domain, allowed_hosts)):
            return None
    return parts.path


validate redirect