Hello,

I think there is a missing error in the ERRORS section of sendto(3p)

When doing a sendto() to a Link-local scope IPv6 address on a socket 
that is bound to in6addr_any which has not been set 
setsockopt(IPV6_MULTICAST_IF) to a valid interface value, it fails with 
EADDRNOTAVAIL because it does not know which interface to send the 
multicast packet from.

I can make a patch later.

Regards,
Angel