IPv6 Unique Local Addresses are sometimes used with Network
Prefix Translation to reach the Internet. In that respect
their use is similar to the private IPv4 address ranges
10/8, 172.16/12, and 192.168/16.
Treat them as sufficient for AnyInterfaceUp(), but specifically
exclude Tailscale's own IPv6 ULA prefix to avoid mistakenly
trying to bootstrap Tailscale using Tailscale.
This helps in supporting Google Cloud Run, where the addresses
are 169.254.8.1/32 and fddf:3978:feb1:d745::c001/128 on eth1.
Signed-off-by: Denton Gentry <dgentry@tailscale.com>
Now callers (wgengine/monitor) don't need to mutate the state to remove
boring interfaces before calling State.Equal. Instead, the methods
to remove boring interfaces from the State are removed, as is
the reflect-using Equal method itself, and in their place is
a new EqualFiltered method that takes a func predicate to match
interfaces to compare.
And then the FilterInteresting predicate is added for use
with EqualFiltered to do the job that that wgengine/monitor
previously wanted.
Now wgengine/monitor can keep the full interface state around,
including the "boring" interfaces, which we'll need for peerapi on
macOS/iOS to bind to the interface index of the utunN device.
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
Basically, don't trust the OS-level link monitor to only tell you
interesting things. Sanity check it.
Also, move the interfaces package into the net directory now that we
have it.
