net_get_interfaces is available as of PHP 7.3.0[1].

[1] <https://github.com/php/php-src/pull/2935>

When will this function be documented? It's been a long of time since it was released.

The correct way to call this function is net_get_interfaces().  It takes zero parameters and returns an array on success or a boolean of false on failure.

But what a missed opportunity!

There's currently no way in PHP userland to easily get the local system's DNS server list and other key network configuration information in a cross-platform fashion (especially Windows).  That's a significant oversight and something that this function or one like it could easily solve.  It's unfortunate that the original implementer didn't realize the larger need.

On Windows, this function calls the GetAdaptersAddresses() Win32 API but then fails to fully utilize the massive structure that is returned.  (IP_ADAPTER_ADDRESSES is a stupidly huge structure because...Microsoft.)  PHP only returns Unicast adapter information to userland while flat out ignoring the DNS server, Anycast, Multicast, and DHCP entries.  The information is right there but not utilized anywhere.

While GetAdaptersAddresses() returns a bunch of useful information in a single API call, *NIXes can obtain the same information as well through a variety of means.  For example, calling res_ninit() for the DNS server list.  Linux is also notably missing the adapter MAC address in this function despite it supposedly being available via getifaddrs().  I believe that is a bug in this userland function since the AF_PACKET/AF_LINK type contain the MAC rather than an IP address.  As a result, the first "unicast" item in the returned array for each interface on Linux is actually the MAC but doesn't show it since PHP attempts to interpret the data as an IP address.  As a result, just 'flags' and 'family' (17) show up in the output.  This means that net_get_interfaces() is buggy and inconsistent as well across all platforms.

The interface metrics are also notably missing across all platforms despite that information also being readily available (at least on Windows).  Interface metrics dictate some routing information for packets.

As I said, this is a missed opportunity.  The lack of documentation is a comparatively minor issue to what could and should actually exist.

Closing per <https://github.com/php/doc-en/commit/de14580fb32c39675f69937dd215f1744d0874d9>.