From mboxrd@z Thu Jan  1 00:00:00 1970
Date: Tue, 16 Apr 1996 16:30:05 -0400
From: forsyth@plan9.cs.york.ac.uk forsyth@plan9.cs.york.ac.uk
Subject: Unix and Plan9
Topicbox-Message-UUID: 43e9b9ac-eac8-11e9-9e20-41e7f4b1d025
Message-ID: <19960416203005.40GYTt7ACQFpY1SQwAK5SR-hcEtr1LVmaFhCUdTm2oQ@z>

>>So far, I know I can use ipinfo() to get some info. but not all of them.

some of that, including
>>udp.c:  (void) ioctl(udp_socket, SIOCGIFFLAGS, ifr) - get flags

is peculiar to specific unix implementations (ie, not common even amongst all unix implementations,
let alone plan 9), and isn't necessarily relevant.
what is the application?