Add OpenVPN status helper example from corresponding ticket

Change-Id: I912d943cdc7024e3ddd92e0a122ac2dd4fbf0a18
Related: SYS#2655

contrib/openvpn-status-export.pl

@@ -0,0 +1,124 @@
+#!/usr/bin/perl -w
+use strict;
+
+# Script to export the OpenVPN daemon status information (which clients
+# are connected from where) as a JSON file that can be served via HTTP.
+#
+# (C) 2015 by sysmocom - s.f.m.c. GmbH, All rights reserved.
+# Author: Harald Welte
+
+use JSON;
+use Linux::Inotify2;
+use Net::Netmask;
+
+my $OPENVPN_STATE_FILE = "/var/tmp/openvpn.status";
+my $JSON_OUTPUT_FILE = "/var/www/openvpn/status.json";
+
+my $srcip_table = {
+	'Destination 1' => [
+		'127.0.0.0/8',
+		],
+	'Peer 2' => [
+		'8.8.0.0/16', '1.2.3.0/18',
+		],
+};
+
+my %netblocks;
+
+sub read_netmask_table($)
+{
+	my ($t) = @_;
+
+	foreach my $k (keys %$t) {
+		my $table = {};
+		foreach my $net (@{$$t{$k}}) {
+			my $block = new Net::Netmask($net);
+			$block->storeNetblock($table);
+		}
+		$netblocks{$k} = $table;
+	}
+}
+
+sub classify_srcip($)
+{
+	my ($ip) = @_;
+	foreach my $k (%netblocks) {
+		my $block = findNetblock($ip, $netblocks{$k});
+		if ($block) {
+			return $k;
+		}
+	}
+	return undef;
+}
+
+# read the openvpn.status file and parse it, return hash reference to
+# its contents.
+sub get_openvpn_clients($)
+{
+	my ($fname) = @_;
+	my $state = 'init';
+	my $href;
+	my @clients;
+
+	$$href{version} = 1;
+
+	open(INFILE, "<", $fname);
+	while (my $line = <INFILE>) {
+		chomp($line);
+		if ($line =~ /^OpenVPN CLIENT LIST$/) {
+			$state = 'client_list';
+		} elsif ($line =~ /^ROUTING\ TABLE$/) {
+			$state = 'routing_table';
+		} else {
+			if ($state eq 'client_list') {
+				my %cl;
+				if ($line =~ /^Updated,(.*)/) {
+					$$href{updated} = $1;
+				} elsif ($line =~ /^(\S+),([0-9\.]+)\:(\d+),(\d+),(\d+),(.*)$/) {
+					$cl{name} = $1;
+					$cl{srcip} = $2;
+					$cl{operator} = classify_srcip($2);
+					$cl{srcport} = $3 + 0;
+					$cl{bytes_rx} = $4 + 0;
+					$cl{bytes_tx} = $5 + 0;
+					$cl{connected_since} = $6;
+					push(@clients, \%cl);
+				}
+			}
+		}
+	}
+	close(INFILE);
+
+	$$href{clients} = \@clients;
+
+	return $href;
+}
+
+# inotify handler to re-parse/convert openvpn.status on any change
+sub status_in_handler
+{
+	my $e = shift;
+
+	# read/parse openvpn.status
+	my $cl = get_openvpn_clients($e->fullname);
+
+	# write result to file
+	open(OUTFILE, ">", $JSON_OUTPUT_FILE);
+	print(OUTFILE to_json($cl, { pretty => 1 }));
+	close(OUTFILE);
+
+	# also print it to console for debugging
+	print(to_json($cl, { pretty => 1 }));
+}
+
+
+
+# main
+
+read_netmask_table($srcip_table);
+
+my $inotify = new Linux::Inotify2 or die("Can't create inotify object: $!");
+$inotify->watch($OPENVPN_STATE_FILE, IN_MODIFY, \&status_in_handler);
+
+# endless loop, wait for inotify enents
+1 while $inotify->poll;