zulip/corporate/lib/decorator.py

from functools import wraps
from typing import Callable, Optional
from urllib.parse import urlencode, urljoin

from django.conf import settings
from django.http import HttpRequest, HttpResponse, HttpResponseRedirect
from django.shortcuts import render
from django.urls import reverse
from typing_extensions import Concatenate, ParamSpec

from corporate.lib.remote_billing_util import (
    RemoteBillingIdentityExpiredError,
    get_remote_realm_from_session,
    get_remote_server_and_user_from_session,
)
from corporate.lib.stripe import RemoteRealmBillingSession, RemoteServerBillingSession
from zerver.lib.exceptions import RemoteBillingAuthenticationError
from zerver.lib.subdomains import get_subdomain
from zerver.lib.url_encoding import append_url_query_string
from zilencer.models import RemoteRealm

ParamT = ParamSpec("ParamT")


def is_self_hosting_management_subdomain(request: HttpRequest) -> bool:
    subdomain = get_subdomain(request)
    return settings.DEVELOPMENT and subdomain == settings.SELF_HOSTING_MANAGEMENT_SUBDOMAIN


def self_hosting_management_endpoint(
    view_func: Callable[Concatenate[HttpRequest, ParamT], HttpResponse]
) -> Callable[Concatenate[HttpRequest, ParamT], HttpResponse]:
    @wraps(view_func)
    def _wrapped_view_func(
        request: HttpRequest, /, *args: ParamT.args, **kwargs: ParamT.kwargs
    ) -> HttpResponse:
        if not is_self_hosting_management_subdomain(request):  # nocoverage
            return render(request, "404.html", status=404)
        return view_func(request, *args, **kwargs)

    return _wrapped_view_func


def authenticated_remote_realm_management_endpoint(
    view_func: Callable[Concatenate[HttpRequest, RemoteRealmBillingSession, ParamT], HttpResponse]
) -> Callable[Concatenate[HttpRequest, ParamT], HttpResponse]:
    @wraps(view_func)
    def _wrapped_view_func(
        request: HttpRequest,
        /,
        *args: ParamT.args,
        **kwargs: ParamT.kwargs,
    ) -> HttpResponse:
        if not is_self_hosting_management_subdomain(request):  # nocoverage
            return render(request, "404.html", status=404)

        realm_uuid = kwargs.get("realm_uuid")
        if realm_uuid is not None and not isinstance(realm_uuid, str):  # nocoverage
            raise TypeError("realm_uuid must be a string or None")

        try:
            remote_realm = get_remote_realm_from_session(request, realm_uuid)
        except RemoteBillingIdentityExpiredError as e:
            # The user had an authenticated session with an identity_dict,
            # but it expired.
            # We want to redirect back to the start of their login flow
            # at their {realm.host}/self-hosted-billing/ with a proper
            # next parameter to take them back to what they're trying
            # to access after re-authing.
            # Note: Theoretically we could take the realm_uuid from the request
            # path or params to figure out the remote_realm.host for the redirect,
            # but that would mean leaking that .host value to anyone who knows
            # the uuid. Therefore we limit ourselves to taking the realm_uuid
            # from the identity_dict - since that proves that the user at least
            # previously was successfully authenticated as a billing admin of that
            # realm.
            realm_uuid = e.realm_uuid
            server_uuid = e.server_uuid
            uri_scheme = e.uri_scheme
            if realm_uuid is None:
                # This doesn't make sense - if get_remote_realm_from_session
                # found an expired identity dict, it should have had a realm_uuid.
                raise AssertionError

            assert server_uuid is not None, "identity_dict with realm_uuid must have server_uuid"
            assert uri_scheme is not None, "identity_dict with realm_uuid must have uri_scheme"

            try:
                remote_realm = RemoteRealm.objects.get(uuid=realm_uuid, server__uuid=server_uuid)
            except RemoteRealm.DoesNotExist:
                # This should be impossible - unless the RemoteRealm existed and somehow the row
                # was deleted.
                raise AssertionError

            # Using EXTERNAL_URI_SCHEME means we'll do https:// in production, which is
            # the sane default - while having http:// in development, which will allow
            # these redirects to work there for testing.
            url = urljoin(uri_scheme + remote_realm.host, "/self-hosted-billing/")

            page_type = get_next_page_param_from_request_path(request)
            if page_type is not None:
                query = urlencode({"next_page": page_type})
                url = append_url_query_string(url, query)

            return HttpResponseRedirect(url)

        billing_session = RemoteRealmBillingSession(remote_realm)
        return view_func(request, billing_session)

    return _wrapped_view_func


def get_next_page_param_from_request_path(request: HttpRequest) -> Optional[str]:
    # Our endpoint URLs in this subsystem end with something like
    # /sponsorship or /plans etc.
    # Therefore we can use this nice property to figure out easily what
    # kind of page the user is trying to access and find the right value
    # for the `next` query parameter.
    path = request.path
    if path.endswith("/"):
        path = path[:-1]

    page_type = path.split("/")[-1]

    from corporate.views.remote_billing_page import (
        VALID_NEXT_PAGES as REMOTE_BILLING_VALID_NEXT_PAGES,
    )

    if page_type in REMOTE_BILLING_VALID_NEXT_PAGES:
        return page_type

    # Should be impossible to reach here. If this is reached, it must mean
    # we have a registered endpoint that doesn't have a VALID_NEXT_PAGES entry
    # or the parsing logic above is failing.
    raise AssertionError(f"Unknown page type: {page_type}")


def authenticated_remote_server_management_endpoint(
    view_func: Callable[Concatenate[HttpRequest, RemoteServerBillingSession, ParamT], HttpResponse]
) -> Callable[Concatenate[HttpRequest, ParamT], HttpResponse]:
    @wraps(view_func)
    def _wrapped_view_func(
        request: HttpRequest,
        /,
        *args: ParamT.args,
        **kwargs: ParamT.kwargs,
    ) -> HttpResponse:
        if not is_self_hosting_management_subdomain(request):  # nocoverage
            return render(request, "404.html", status=404)

        server_uuid = kwargs.get("server_uuid")
        if not isinstance(server_uuid, str):
            raise TypeError("server_uuid must be a string")  # nocoverage

        try:
            remote_server, remote_billing_user = get_remote_server_and_user_from_session(
                request, server_uuid=server_uuid
            )
            if remote_billing_user is None:
                # This should only be possible if the user hasn't finished the confirmation flow
                # and doesn't have a fully authenticated session yet. They should not be attempting
                # to access this endpoint yet.
                raise RemoteBillingAuthenticationError
        except (RemoteBillingIdentityExpiredError, RemoteBillingAuthenticationError):
            # In this flow, we can only redirect to our local "legacy server flow login" page.
            # That means that we can do it universally whether the user has an expired
            # identity_dict, or just lacks any form of authentication info at all - there
            # are no security concerns since this is just a local redirect.
            url = reverse("remote_billing_legacy_server_login")
            page_type = get_next_page_param_from_request_path(request)
            if page_type is not None:
                query = urlencode({"next_page": page_type})
                url = append_url_query_string(url, query)

            return HttpResponseRedirect(url)

        assert remote_billing_user is not None
        billing_session = RemoteServerBillingSession(
            remote_server, remote_billing_user=remote_billing_user
        )
        return view_func(request, billing_session)

    return _wrapped_view_func