Adding guard rails to prevent user error in DNSMASQ

[mojoaj]

Yesterday i was migrating from ISC DHCP to DNSMASQ, one of my VLANs requires me to set the DNS to 8.8.8.8 through DHCP.

I was setting this up using the DHCP options tab and i accidentally selected the DHCPv6 option instead of DHCPv4. the value field is the same for both, when i entered 8.8.8.8 into the value field with the DHCP6 DNS-server option selected, it crashed DNSMASQ for my entire network, it took me a while to figure out that i had selected the DNS-server option for DHCP6 instead of DHCP4.

There should either be 2 different value fields, one for DHCPv6 and one for v4, or the value field should not accept ipv4 addresses when the DHCPv6 option is selected in the dropdown