1#!/usr/perl5/bin/perl -w
2#
3# CDDL HEADER START
4#
5# The contents of this file are subject to the terms of the
6# Common Development and Distribution License (the "License").
7# You may not use this file except in compliance with the License.
8#
9# You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10# or http://www.opensolaris.org/os/licensing.
11# See the License for the specific language governing permissions
12# and limitations under the License.
13#
14# When distributing Covered Code, include this CDDL HEADER in each
15# file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16# If applicable, add the following below this CDDL HEADER, with the
17# fields enclosed by brackets "[]" replaced with your own identifying
18# information: Portions Copyright [yyyy] [name of copyright owner]
19#
20# CDDL HEADER END
21#
22
23#
24# Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
25# Use is subject to license terms.
26#
27
28#
29# get.ipv4remote.pl [tcpport]
30#
31# Find an IPv4 reachable remote host using both ifconfig(8) and ping(8).
32# If a tcpport is specified, return a host that is also listening on this
33# TCP port.  Print the local address and the remote address, or an
34# error message if no suitable remote host was found.  Exit status is 0 if
35# a host was found.
36#
37
38use strict;
39use IO::Socket;
40
41my $MAXHOSTS = 32;			# max hosts to port scan
42my $TIMEOUT = 3;			# connection timeout
43my $tcpport = @ARGV == 1 ? $ARGV[0] : 0;
44
45#
46# Determine local IP address
47#
48my $local = "";
49my $remote = "";
50my %Broadcast;
51my $up;
52open IFCONFIG, '/usr/sbin/ifconfig -a |' or die "Couldn't run ifconfig: $!\n";
53while (<IFCONFIG>) {
54	next if /^lo/;
55
56	# "UP" is always printed first (see print_flags() in ifconfig.c):
57	$up = 1 if /^[a-z].*<UP,/;
58	$up = 0 if /^[a-z].*<,/;
59
60	# assume output is "inet X ... broadcast Z":
61	if (/inet (\S+) .* broadcast (\S+)/) {
62		my ($addr, $bcast) = ($1, $2);
63		$Broadcast{$addr} = $bcast;
64		$local = $addr if $up and $local eq "";
65		$up = 0;
66	}
67}
68close IFCONFIG;
69die "Could not determine local IP address" if $local eq "";
70
71#
72# Find the first remote host that responds to an icmp echo,
73# which isn't a local address.
74#
75open PING, "/usr/sbin/ping -ns $Broadcast{$local} 56 $MAXHOSTS |" or
76    die "Couldn't run ping: $!\n";
77while (<PING>) {
78	if (/bytes from (.*): / and not defined $Broadcast{$1}) {
79		my $addr = $1;
80
81		if ($tcpport != 0) {
82			#
83			# Test TCP
84			#
85			my $socket = IO::Socket::INET->new(
86				Proto    => "tcp",
87				PeerAddr => $addr,
88				PeerPort => $tcpport,
89				Timeout  => $TIMEOUT,
90			);
91			next unless $socket;
92			close $socket;
93		}
94
95		$remote = $addr;
96		last;
97	}
98}
99close PING;
100die "Can't find a remote host for testing: No suitable response from " .
101    "$Broadcast{$local}\n" if $remote eq "";
102
103print "$local $remote\n";
104