[lwip-devel] DNS servers from DHCP, DHCPv6, NDP

[Craig McQueen]

I'm looking into enabling IPv6 in lwIP. Something I noticed is, the DNS servers may be set to the IPv4 ones obtained from DHCP, or IPv6 ones obtained from DHCPv6 or NDP, but not the sum of all of them. I've had the situation where IPv6 DNS servers were down, but lwIP didn't save the IPv4 ones, and so had no fallback.

Looking in the code, I see calls to `dns_setserver()` in `dhcp.c`, `dhcp6.c`, `nd6.c`. In each case, it's in a for-loop that sets the `numdns` parameter starting at 0 in each case.

I notice in `dhcp6.c`, there is a comment saying /* @todo: do we need a different offset than DHCP(v4)? */. Yes I think something like that is needed.

--
Craig McQueen

		Craig McQueen Embedded Systems Engineer
		t e w	: : :	+61 3 9780 4378 craig.mcqueen@innerrange.com innerrange.com
Inner Range • 1 Millennium Court • Knoxfield • Victoria • 3180 • Australia