[lwip-users] DNS look-up with domain search

[Craig McQueen]

I'm interested in doing DNS look-ups that possibly include a domain search list.

I'm successfully using LWIP_HOOK_DHCP_APPEND_OPTIONS() and 
LWIP_HOOK_DHCP_PARSE_OPTION() to get a domain from DHCP via DHCP option 15.

Now I'm interested in possibly using that as a search domain. So if doing a 
look-up for "server", and DHCP option 15 specifies domain "example.com", then 
DNS could do a search for "server.example.com". But not if the original look-up 
name includes a trailing dot. If the original name includes a trailing dot, 
e.g. "server.com.", then it wouldn't try "server.com.example.com".

Note that the current functions in dns.c will fail a DNS look-up given a string 
that ends with a trailing dot. Technically is this correct or incorrect? See 
the following which discusses trailing dots in domain names:
http://www.dns-sd.org/trailingdotsindomainnames.html

-- 
Craig McQueen