Fix IPv4 routing
Fix IPv4 routing

Code was differentiating between IPv4 and IPv6 by using the length of a net.IP type,
which made in wrongly assume that all IP addresses were IPv6.

To quote the docs (https://golang.org/pkg/net/#IP):
"Referring to an IP address as an IPv4 address or an IPv6 address is a semantic property
of the address, not just the length of the byte slice: a 16-byte slice can still be an IPv4 address."

google/gopacket,google/gopacket,google/gopacket