Source code for jivago.wsgi.routing.cors.cors_preflight_request_handler

from typing import Optional

from jivago.lang.annotations import Override
from jivago.lang.nullable import Nullable
from jivago.wsgi.invocation.route_handler import RouteHandler
from jivago.wsgi.request.headers import Headers
from jivago.wsgi.request.request import Request
from jivago.wsgi.request.response import Response

ALLOW_ORIGIN_HEADER = 'Access-Control-Allow-Origin'




class CorsPreflightRequestHandler(RouteHandler):

    def __init__(self, cors_headers: Headers):
        self.cors_headers = cors_headers
        self.allowed_origin = self.cors_headers[ALLOW_ORIGIN_HEADER] \
            if ALLOW_ORIGIN_HEADER in self.cors_headers \
            else '*'



    @Override
    def invoke(self, request: Request) -> Response:
        origin = Nullable(request.headers['Origin'])
        if self.should_allow(origin):
            response = Response(200, self.cors_headers, "")
        else:
            response = Response(400, self.cors_headers, "")

        if 'Vary' not in response.headers and response.headers[ALLOW_ORIGIN_HEADER] != '*':
            response.headers['Vary'] = 'Origin'

        return response




    def should_allow(self, origin: Nullable[str]) -> bool:
        if self.allowed_origin == '*':
            return True
        return origin \
            .map(lambda x: x.startswith(self.allowed_origin)) \
            .orElse(False)