1. Add special option where an empty host means 'wildcard for IPv4 and/or IPv6'
which means ':1234' can be used to set only the portnum.
2. Only add this protocol wildcard if --autolisten=1 (default)
and no other addresses specified.
3. Pass it down to gossipd, so it can handle errors correctly: in most cases,
it's fatal not to be able to bind to a port, but for this case, it's OK
if we can only bind to one of IPv4/v6 (fatal iff neither).
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This replacement is a little menial, but it explicitly catches all
the places where we allow a local socket. The actual implementation of
opening a AF_UNIX socket is almost hidden in the patch.
The detection of "valid address" is now more complex:
p->addr.itype != ADDR_INTERNAL_WIREADDR || p->addr.u.wireaddr.type != ADDR_TYPE_PADDING
But most places we do this, we should audit: I'm pretty sure we can't
get an invalid address any more from gossipd (they may be in db, but
we should fix that too).
Closes: #1323
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>