Method process_redirect

src/websockets/asyncio/client.py:473–532

Determine whether a connection error is a redirect that can be followed. Return the new URI if it's a valid redirect. Else, return an exception.

(self, exc: Exception)

        return connection

    def process_redirect(self, exc: Exception) -> Exception | str:
        """
        Determine whether a connection error is a redirect that can be followed.

        Return the new URI if it's a valid redirect. Else, return an exception.

        """
        if not (
            isinstance(exc, InvalidStatus)
            and exc.response.status_code
            in [
                300,  # Multiple Choices
                301,  # Moved Permanently
                302,  # Found
                303,  # See Other
                307,  # Temporary Redirect
                308,  # Permanent Redirect
            ]
            and "Location" in exc.response.headers
        ):
            return exc

        old_ws_uri = parse_uri(self.uri)
        new_uri = urllib.parse.urljoin(self.uri, exc.response.headers["Location"])
        new_ws_uri = parse_uri(new_uri)

        # If connect() received a socket, it is closed and cannot be reused.
        if self.connection_kwargs.get("sock") is not None:
            return ValueError(
                f"cannot follow redirect to {new_uri} with a preexisting socket"
            )

        # TLS downgrade is forbidden.
        if old_ws_uri.secure and not new_ws_uri.secure:
            return SecurityError(f"cannot follow redirect to non-secure URI {new_uri}")

        # Apply restrictions to cross-origin redirects.
        if (
            old_ws_uri.secure != new_ws_uri.secure
            or old_ws_uri.host != new_ws_uri.host
            or old_ws_uri.port != new_ws_uri.port
        ):
            # Cross-origin redirects on Unix sockets don't quite make sense.
            if self.connection_kwargs.get("unix", False):
                return ValueError(
                    f"cannot follow cross-origin redirect to {new_uri} "
                    f"with a Unix socket"
                )

            # Cross-origin redirects when host and port are overridden are ill-defined.
            if (
                self.connection_kwargs.get("host") is not None
                or self.connection_kwargs.get("port") is not None
            ):
                return ValueError(
                    f"cannot follow cross-origin redirect to {new_uri} "
                    f"with an explicit host or port"
                )