from paste.proxy import TransparentProxy
from webob import Request
from webob.exc import HTTPForbidden

class SimpleProxy(object):
    
    def __init__(self, proxy):
        self.proxy = proxy
        
    def do_proxy(self, req, environ, start_response):
        req.remove_conditional_headers()
        resp = req.get_response(self.proxy)
        resp.decode_content()
        return resp

    def __call__(self, environ, start_response):
        req = Request(environ)
        resp = self.do_proxy(req, environ, start_response)
        return resp(environ, start_response)

class XXXProxy(SimpleProxy):

    def do_proxy(self, req, environ, start_response):
        resp = super(XXXProxy, self).do_proxy(req, environ, start_response)
        if not self.valid(resp.body):
            return HTTPForbidden()
        return resp

    def valid(self, body):
        return not 'xxx' in body


def main():
    app = XXXProxy(TransparentProxy())
    from paste.httpserver import serve
    serve(app, 'localhost', 3127)

if __name__ == '__main__':
    main()