Incorrect type annotation for Session.peer

[cuu508]

The type annotation for Session.peer is currently:

self.peer: Optional[str] = None

This attribute appears to be set in connection_made() like so:

self.session.peer = transport.get_extra_info("peername")

Where transport is an instance of asyncio.BaseTransport.

Looking at BaseTransport docs, get_extra_info("peername") calls socket.getpeername() and returns the result.

For IPv4 sockets at least, socket.getpeername() seems to return an ip-address,port tuple. So I think a more accurate annotation for Session.peer would be something like tuple[str, int] | None.

[cuu508]

This is a little tricky than I thought :-)

aiosmtpd can listen on IPv4 address, on IPv6 address (by using aiosmtpd.controller.Controller), and to an UNIX socket (by using aiosmtpd.controller.UnixSocketController). The type of Session.peer is different in each case:

• IPv4: tuple[str, int] (hostname, port)
• IPv6: tuple[str, int, int, int], (hostname, port, flowinfo, scope_id)
• UNIX socket: str (not sure what it is supposed to return, in practice when testing locally with swaks as the client, I got an empty string back)

So the combined type annotation would be something like

tuple[str, int] | tuple[str, int, int, int] | str | None

Or, in Python 3.8 compatible syntax:

Union[Tuple[str, int], Tuple[str, int, int, int], str, None]