transmit_speed and receive_speed can get set to very large values on Windows

[relativityspace-jsmith]

Hi! I have noticed that, on Windows, the transmit_speed and receive_speed values are set to the max value (2^64 - 1) for disconnected Ethernet interfaces, as well as virtual interfaces (e.g. "Microsoft Wi-Fi Direct Virtual Adapter #2"). The documentation doesn't describe this, but it seems to me like 2^64-1 is being used as a "do not use" value for this field. Would it be worth updating the library to make it return None for the link speed in this situation?

[shellrow]

Thanks for reporting this! and sorry for late response.

Absolutely right — I agree it makes sense for the library to treat this case explicitly and return None instead.

Although this behavior isn't explicitly documented in the official Windows API docs, it seems to follow a common convention in Windows where u64::MAX (or -1 in signed terms) is used to represent an "invalid" or "unknown" value — for example, similar usage can be seen in tests within the windows-rs crate.

Currently, these values are wrapped in Some(...), which can be misleading.
I plan to update the implementation in the next release to return None when the value is u64::MAX, so the semantics of Option<u64> are preserved correctly.