[Bug 268305] ether_gen_addr() uses wrong OUI range

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=268305

            Bug ID: 268305
           Summary: ether_gen_addr() uses wrong OUI range
           Product: Base System
           Version: 13.1-RELEASE
          Hardware: Any
                OS: Any
            Status: New
          Severity: Affects Some People
          Priority: ---
         Component: kern
          Assignee: bugs@FreeBSD.org
          Reporter: topical@gmx.net

According to documentation in /usr/include/net/ieee_oui.h ether_gen_addr()
should generate OUIs in range 100000..10ffff. In practise, is generates OUIs in
range 000000..00ffff or 100000..10ffff. 

In if_ethersubr.c you see

  addr = ((digest[0] << 16) | (digest[1] << 8) | digest[2]) &
OUI_FREEBSD_GENERATED_MASK;
  addr = OUI_FREEBSD(addr);

The first line generates an address in range 000000..00ffff or 100000..10ffff 

It should be 

  addr = ((digest[0] << 16) | (digest[1] << 8) | digest[2]) & 0xffff;

Probably, we should define a macro for 0xffff

The second list uses OUI_FREEBSD which doesn't add 0x100000 to the generated
address.

It should be 

  addr = OUI_FREEBSD(addr | 0x100000);

In general, definitions in ieee_oui.h are a bit misleading. Definition of
OUI_FREEBSD_GENERATED_MASK is a mixture of an AND-mask 0xffff and the
allocation number 0x10. 

It would be better to separate them, e.g.

  OUI_FREEBSD_GENERATED_BASE 0x100000
  OUI_FREEBSD_GENERATED_MASK 0xffff

  OUI_FREEBSD_NVME_BASE 0x200000
  OUI_FREEBSD_NVME_MASK 0xffff

This way, you can cleanly define e.g. range "0x41800...0x41fff"

  OUI_FREEBSD_FOO_BASE 0x41800
  OUI_FREEBSD_FOO_MASK 0x7ff

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