* rename bin/ to '.bin/'

[lab.git] / .bin / get_ip_from_ioctl.pl

diff --git a/.bin/get_ip_from_ioctl.pl b/.bin/get_ip_from_ioctl.pl
new file mode 100755 (executable)
index 0000000..151b506
--- /dev/null
+++ b/.bin/get_ip_from_ioctl.pl
@@ -0,0 +1,36 @@
+#!/usr/bin/perl
+use strict;
+use warnings;
+require 'sys/ioctl.ph';
+use Socket;
+
+my %interfaces;
+my $max_addrs = 30;
+socket(my $socket, AF_INET, SOCK_DGRAM, 0) or die "socket: $!";
+
+{
+    my $ifreqpack = 'a16a16';
+    my $buf = pack($ifreqpack, '', '') x $max_addrs;
+    my $ifconf = pack('iP', length($buf), $buf);
+
+    # This does the actual work
+    ioctl($socket, SIOCGIFCONF(), $ifconf) or die "ioctl: $!";
+
+    my $len = unpack('iP', $ifconf);
+    substr($buf, $len) = '';
+
+    %interfaces = unpack("($ifreqpack)*", $buf);
+
+    unless (keys(%interfaces) < $max_addrs) {
+        # Buffer was too small
+        $max_addrs += 10;
+        redo;
+    }
+}
+
+for my $addr (values %interfaces) {
+    $addr = inet_ntoa((sockaddr_in($addr))[1]);
+}
+
+use Data::Dumper;
+print Dumper \%interfaces;