have_route_to auth protection is insufficient

[jkroonza]

in pppd/auth.c have_route_to(0) is used to check if we've got a default route prior to starting pppd, and if so, require auth.

In a future world where there is no IPv4 this is not sufficient, meaning we either need to check for (have_route_to(0) || have_route6_to(0)), or we need to not rely on this check at all.

I need to think about this in order to make a recommendation.

Further, to make matters worse, it may in theory be possible that our system depends on dynamic routing using eg OSPF/BGP to obtain a default route, but some other system may already initiated pppd, as such, I honestly think the check is shortsighted in some way or another.

No recommendation as of right now.

[Neustradamus]

@paulusmack, @sthibaul, @enaess, @RICCIARDI-Adrien: @jkroonza has done this ticket.