Ping used to provide some sort of packet sniffing capabilities, this was
in an era where hubs were used and tcpdump wasn't invented.
pr_iph() is a function that prints the IP header of the packet.
pr_retip() is essentially a wrapper function to pr_iph(), that also
displays the source and destination ports of a TCP or UDP packet.
After ef9e6dc7ee some of this
functionality was almost removed, to only display packets sent by us
(26+ years ago).
At this point, reaching this code path was only possible by doctoring
the original packet.
After 46d7b45a26 this code path can never
be reached.
Remove the code.
Reviewed by: markj
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D38475
1dc1f6bd31