#!/usr/bin/perl
#
# modem.pl - Report the status a Motorola 'SURFboard' cable modem
# (models: SB5101, SB5100E)
#
# copyright(C) 2007 Scott Mazur <scott.AT.littlefish.ca>

# GNU General Public License
# --------------------------------------------------------------------
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330,
# Boston, MA  02111-1307  USA

# requires:
#     Time::Local;
#     LWP::Simple;

my $ver = '0.11';

# Version 0.11
# - now handles SB5100E model as well

# The Motorola 'SURFboard' cable modem includes a built in web
# interface that contains useful information like signal to noise
# ratios and power levels.
#
# This script uses LWP:Simple to scrape the status page from the
# modem and report the most useful information in a single line:
#   Down power, Signal to Noise, Up power
#
# If the script is not running interactively (like say from a cron
# job) the output line is prefixed with a standard log time stamp
# and Errors/warnings are duplicated to STDOUT and STDERR.  This
# is so that cron jobs can report errors while still sending
# output to a log file

use strict;
use warnings;

use Time::Local;
use LWP::Simple;

use constant SB5101_URL => 'http://192.168.100.1/RgSignal.asp';
use constant SB5100E_URL => 'http://192.168.100.1/signaldata.html';

# are we running from a shell or maybe crond?
use constant I_am_interactive => (-t STDIN and -t STDOUT);

# format current time into standard system log file format
my $tm_str = localtime;
$tm_str = sprintf("$1 % 2d $3", $2)
	if $tm_str =~ m/^\S+\s+(\S+)\s+(\S+)\s+(\S+)/;

# print message in addition to die unless interactive
# This lets you pipe STDOUT to a file yet still get
# a message on the console (or from cron)
sub My_Die {
	my $msg = shift;
	print "$tm_str $msg\n" unless I_am_interactive;
	die "$msg\n";
}

# main script
#############

# get the modem status page
my $content = get(SB5101_URL)
	|| get(SB5100E_URL)
	|| My_Die("Couldn't get modem signal page!");

# clean up the html a bit for parsing
$content =~ s/\n//g;     # drop new lines
$content =~ s!</?t[dr]>! !ig; # strip table tags
$content =~ s/\s\s+/ /g; # reduce double spaces

# check that the page has what we expect
$content =~ m{
	Frequency \s (\d+\s Hz) \s (Locked\s)?
	Signal \s To \s Noise \s Ratio \s ([\d.]+\s dB) \s
	Power \s Level \s ([\d.-]+\s dBmV)
	}xi or My_Die('content failed!');

# build a hash of signal strength values
my %results = (
	DownStream => {freq => $1, sn => $3, power => $4},
	UpStream => {channel => '?', freq => '? Hz', power => '0  dBmV'}
	);

# get the upstream values
$results{UpStream} = {channel => $1, freq => $2, power => $5}
	if $content =~ m/ID (\d+) Frequency (\d+ Hz)( Ranged)? Power( Level)? ([\d.-]+ dBmV)/i;

# create the result message
my $msg = "Down Power: $results{DownStream}->{power}" .
		"  S/N: $results{DownStream}->{sn}" .
		"  Up Power: $results{UpStream}->{power}";

# check up power for reasonable range
my $power = $results{UpStream}->{power};

# strip down to raw number
my ($stripped) = $power =~ m/^([\d.-]+)/;

my $status = '';
$status = 'Up Power high!' if $stripped > 54;
$status = 'Up Power low!' if $stripped < 36;

# better call the cable guy!
if ($status) {
	warn "$status $power\n";
	$msg .= " warning: $status";
}

# check down power for reasonable range
$power = $results{DownStream}->{power};

# strip down to raw number
($stripped) = $power =~ m/^([\d.-]+)/;

$status = '';
$status = 'Down Power high!' if $stripped > 10;
$status = 'Down Power low!' if $stripped < -10;

# not good either!
if ($status) {
	warn "$status $power\n";
	$msg .= " warning: $status";
}

$msg = "$tm_str $msg" unless I_am_interactive;
print "$msg\n";

# debug dump all values
# foreach (qw(DownStream UpStream)) {
# 	print "$_ - ";
# 	my $hash = $results{$_};
# 	foreach (sort keys %$hash) {
# 		print "  $_: $hash->{$_}";
# 	}
# 	print "\n";
# }

exit;