Re: nss_dns addons and thread safety

[George Beshers <gbeshers at comcast dot net>]

> Be specific about what code you would like to be able to call more 
easily.

The motivation is to duplicate the link-local capabilities currently in 
MacOSX.
These are implemented using link-local multicast in both IPv4 and IPv6.

In resolv/  I would like to
1) add an nss_mdns directory
2) have a hook to dynamically "replace" the call to __libc_res_nsend() in
__libc_res_nquery with a call to __libc_res_mcsend() [multi-cast send].

This specific point is, I believe, correct because it inside the domain 
search
loop (from the search line in resolv.conf) but outside the nameserver loop.
The only appropriate responders are on the local network so the multicast
is independent of the specified nameservers.

To clarify the motivation, consider a home network with a wireless router.
DHCP is available, but when a friend, john, comes over with a laptop the 
router
doesn't have bind (or some other dns) running to assist with resolving
names.  Link-local multicast solves this problem nicely because
"johnscomputer.local" can be found; or just "johnscomputer" if local
is in the search path.

Another situation where this is useful is when linux laptops in the same 
room
can setup a "link-local" wireless network.