# This file is part of the Wapiti project (https://wapiti-scanner.github.io)
# Copyright (C) 2020-2022 Nicolas Surribas
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
from typing import Optional

from httpx import RequestError

from wapitiCore.attack.attack import Attack
from wapitiCore.net import Request
from wapitiCore.net.response import Response
from wapitiCore.net.csp_utils import csp_header_to_dict, CSP_CHECK_LISTS, check_policy_values
from wapitiCore.definitions.csp import NAME, WSTG_CODE
from wapitiCore.main.log import log_red

MSG_NO_CSP = "CSP is not set"
MSG_CSP_MISSING = "CSP attribute \"{0}\" is missing"
MSG_CSP_UNSAFE = "CSP \"{0}\" value is not safe"


# This module check the basics recommendations of CSP
class ModuleCsp(Attack):
    """Evaluate the security level of Content Security Policies of the web server."""
    name = "csp"

    async def must_attack(self, request: Request, response: Optional[Response] = None):
        if self.finished:
            return False

        if request.method == "POST":
            return False

        return request.url == await self.persister.get_root_url()

    async def attack(self, request: Request, response: Optional[Response] = None):
        self.finished = True
        request_to_root = Request(request.url)

        try:
            response: Response = await self.crawler.async_send(request_to_root, follow_redirects=True)
        except RequestError:
            self.network_errors += 1
            return

        if "Content-Security-Policy" not in response.headers:
            log_red(MSG_NO_CSP)
            await self.add_vuln_low(
                category=NAME,
                request=request_to_root,
                info=MSG_NO_CSP,
                wstg=WSTG_CODE,
                response=response
            )
        else:
            csp_dict = csp_header_to_dict(response.headers["Content-Security-Policy"])

            for policy_name in CSP_CHECK_LISTS:
                result = check_policy_values(policy_name, csp_dict)

                if result <= 0:
                    if result == -1:
                        info = MSG_CSP_MISSING.format(policy_name)
                    else:  # result == 0
                        info = MSG_CSP_UNSAFE.format(policy_name)

                    log_red(info)
                    await self.add_vuln_low(
                        category=NAME,
                        request=request_to_root,
                        info=info,
                        wstg=WSTG_CODE,
                        response=response
                    )
