#!/usr/bin/perl -w
#
# check_sip plugin for nagios
# $Revision: 1.4 $
#
# Nagios plugin to check SIP servers
#
# By Sam Bashton, Bashton Ltd
# bashton.com/content/nagiosplugins
# Michael Hirschbichler, Institute of Broadband Communications, 
#  Vienna University of Technology
# Ryanny Lin
# Craig Gowing, credativ Ltd
# http://www.credativ.co.uk/
#
#   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., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

use strict;
use lib "/usr/lib64/nagios/plugins";
use utils qw($TIMEOUT %ERRORS &print_revision &support);
use vars qw($PROGNAME);
use IO::Socket::INET;
#use Sys::Hostname;
use Time::HiRes qw(gettimeofday ualarm);
use Net::Domain qw (hostname hostfqdn hostdomain);
use Switch;

$PROGNAME = "check_sip";
my $VERSION  = "1.4.0";

$ENV{'BASH_ENV'}=''; 
$ENV{'ENV'}='';
$ENV{'PATH'}='';
$ENV{'LC_ALL'}='C';

my ($opt_V,$opt_h,$opt_u,$opt_p,$opt_H, $opt_w, $opt_s, $opt_f);
$opt_V = $opt_h = $opt_u = $opt_p = $opt_H = $opt_w = $opt_s = $opt_f = '';

my $state = 'UNKNOWN';

use Getopt::Long;
Getopt::Long::Configure('bundling');
GetOptions(
  "V"   => \$opt_V,   "version"       => \$opt_V,
  "h"   => \$opt_h,   "help"          => \$opt_h,
  "s"   => \$opt_s,
  "f=s" => \$opt_f,   "fromuri=s"     => \$opt_f,
  "u=s" => \$opt_u,   "uri=s"         => \$opt_u,
  "p=s" => \$opt_p,   "port=s"        => \$opt_p,
  "H=s" => \$opt_H,   "host=s"        => \$opt_H,
  "w=s" => \$opt_w,   "warn=s"	      => \$opt_w
);

# -h displays help
if ($opt_h) { printHelp(); exit $ERRORS{'OK'}; }

# -V display version number
if ($opt_V) {
  print_revision($PROGNAME, $VERSION);
  exit $ERRORS{'OK'};
};

#  Check the sip URI is OK
unless ($opt_u) { printHelp(); exit $ERRORS{'UNKNOWN'} }

# Port is 5060 unless otherwise specified
unless ($opt_p) { $opt_p = 5060 }

# Determine the host from the sip URI if it wasn't specified with -H
unless ($opt_H) { $opt_H = hostFromURI($opt_u) }

# Check the host is valid
unless (utils::is_hostname($opt_H))
{
  print "$opt_H is not a valid hostname\n";
  printHelp();
  exit $ERRORS{"UNKNOWN"};
}

unless ($opt_w) { $opt_w = 5 } # Warn if response takes longer than 5 seconds

### Main code ###############################################################

# Timeout if we don't recieve a response within a suitable timeframe..
my ($startsec, $starttime);
my $resend_times;
my $max_resend;
#my $Total_timeout=0.5;
my ($finishsec, $finishtime);
my $secdiff;
my $rtime;
$SIG{'ALRM'} = sub {
#$Total_timeout+=$TIMEOUT;
  if($resend_times>=($max_resend)){
    ($finishsec, $finishtime) = gettimeofday;
    $secdiff=$finishsec-$startsec;
    $rtime = $secdiff + $finishtime/ 1000000 - $starttime / 1000000;
    print ("SIP timeout: No response from SIP server after $rtime seconds. ($resend_times/$max_resend)\n");
    exit $ERRORS{"CRITICAL"};
  }
};
#alarm($TIMEOUT);
my $localhost = hostfqdn();
$opt_f = getFromURI($opt_f,$localhost,$opt_p);
my $user=getUserPart($opt_f);
my $socket = uconnect($opt_H, $opt_p);
my @localinfo = unpack_sockaddr_in($socket->sockname);
my $req = buildReq($localinfo[0], $opt_u, $opt_f,$user,$localhost);
($startsec, $starttime) = gettimeofday;
my $response;

for($TIMEOUT=0,$resend_times=0,$max_resend=11;$resend_times<=$max_resend;){
$socket->send($req);
$response='';
$resend_times++;
# sip retransmission, totally 35.5 seconds.
switch($resend_times){
  case 1 { ualarm(500000); }
  case 2 { $TIMEOUT=1; alarm($TIMEOUT); }
  case 3 { $TIMEOUT=2; alarm($TIMEOUT); }
  else { $TIMEOUT=4; alarm($TIMEOUT); }
}
#print $resend_times."->".$Total_timeout." $TIMEOUT\n";
$socket->recv($response, 1024) or $state = 'CRITICAL'; # TODO: CHECK and show '503 Service Unavailable' when receiving unreachable ICMP packet.
#get rid of the 100 Trying - provisional response ...
if ($response && getResponseCode($response) eq "100"){
  $socket->recv($response, 1024) or $state = 'CRITICAL';
}
last if ($response);
}
($finishsec, $finishtime) = gettimeofday;
$secdiff=$finishsec-$startsec;
$rtime = $secdiff + (($finishtime - $starttime) / 1000000); # Time taken in seconds
if(checkResponse($response,$rtime,$opt_s)) 
{ 
  if ($rtime > $opt_w) { $state = 'WARNING' }
  else { $state = 'OK' }
}
else { $state = 'CRITICAL' }

exit $ERRORS{$state};

### Subroutines ##############################################################


sub uconnect
{
  my ($host, $port) = @_;
  my $socket = new IO::Socket::INET->new(PeerPort=>$port, Proto=>'udp', PeerAddr=>$host);
  unless ($socket) { print "Unable to connect to $host\n"; exit $ERRORS{'UNKNOWN'} }
  return $socket;
}

sub getFromURI{
  my ($from, $localhost,$localport) = @_;
  if (!("$from" eq "")){
    return "$from:$localport";
  }else
  {
    return "sip:checksip\@$localhost:$localport";
  }
}

sub getUserPart{
  my ($uri) = @_;
  my @uris=split(/\@/,$uri);
  my $user=$uris[0];
  return $user;
}

sub hostFromURI
{
  my ($uri) = @_;
  $uri =~ s/sip:[^\@]+@//;
  return $uri;
}

sub getResponseCode
{
  my ($message) = @_;
  my @messageparts=split(/\ /,$message);
  return $messageparts[1];
}

sub buildReq
{
  my ($localport, $dsturi, $fromuri,$user,$localhost) = @_;
  
  my $req;
  my $tag = genTag();
  my $idtag = genTag();
  my $branch = genBranch();
  $req.= "OPTIONS $dsturi SIP/2.0\r\n";
  $req.= "Via: SIP/2.0/UDP $localhost:$localport;branch=$branch\r\n";
  $req.= "Max-Forwards: 70\r\n";
  $req.= "To: $dsturi\r\n";
  $req.= "From: $fromuri;tag=$tag\r\n";
  $req.= "Call-ID: $idtag\@$localhost\r\n";
  $req.= "CSeq: 1 OPTIONS\r\n";
  $req.= "Contact: <$user\@$localhost:$localport>\r\n";
  $req.= "Accept: application/sdp\r\n";
  $req.= "Content-Length: 0\r\n\r\n";
  return $req;
}

sub genTag
{
  my $tag;
  my @chars = ('a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p',
  'q','r','s','t','u','v','w','x','y','z','0','1','2','3','4','5','6','7','8',
  '9');

  for (my $i = 0; $i < 6; $i++)
  {
    $tag .= $chars[rand(scalar @chars)];
  }
  return $tag;
}

sub genBranch
{
  my $branch = "z9hG4bK";
  my @chars = ('a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p',
  'q','r','s','t','u','v','w','x','y','z','0','1','2','3','4','5','6','7','8',
  '9');

  for (my $i = 0; $i < 11; $i++)
  {
    $branch .= $chars[rand(scalar @chars)];
  }
  return $branch;
}

sub printHelp
{
  print "This plugin tests the sip service on the specified host.\n\n";
  print "Usage: $PROGNAME -u sip:uri\@example.com [-H host -p PORT -f sip:fromuri\@example.com -w WARNTIME -s]\n";
  print "       $PROGNAME [-h | --help]\n";
  print "       $PROGNAME [-V | --version]\n\n";
  print "Options:\n";
  print " -u sip:uri\@example.com\n";
  print "   Full SIP uri, eg sip:uri\@example.com\n";
  print " -h, --help\n";
  print "   Print this help\n";
  print " -V, --version\n";
  print "   Print version information\n";
  print " -H host\n";
  print "   Host name or IP Address to connect to\n";
  print " -p port\n";
  print "   Port to connect to\n";
  print " -f sip:fromuri\@example.com\n";
  print "   Full SIP uri, will be used for the \"From:\"-Header\n";
  print " -s\n";
  print "   Changes default behavior: all SIP-responses will result in an \"OK\"\n\n";


}

sub checkResponse
{
  my ($response, $rtime, $sp_behavior) = @_;
  my @header=split(/\r/,$response);
  my $tstring=$header[0];
  my $rcode=getResponseCode($response);  
  if (!$sp_behavior){
    #in this case, we want to see if the SIP-server is respoding positively to our request
    # Some SUT respond with 100 Trying - assume everything is OK if we get this
    if  ($response =~ /^SIP.+[12]00/){
      print "$tstring, $rtime seconds response time, cnt=".$resend_times."|rtt=".$rtime."s;cnt=".$resend_times.";0.5s;1s;0:10; code=".$rcode."\n";
      return 1;
    } 
    elsif ($response =~ /^SIP.+404 Not Found/) { 
      print "$tstring, $rtime seconds response time, cnt=".$resend_times."|rtt=".$rtime."s;cnt=".$resend_times.";0.5s;1s;0:10; code=".$rcode."\n"; 
      return 0 }
    else { print "Unknown error: $tstring, $rtime seconds response time, cnt=".$resend_times."|rtt=".$rtime."s;cnt=".$resend_times.";0.5s;1s;0:10; code=".$rcode."\n"; return 0; }
  }else{
    #in this case, we accept every response from the server, as long it is SIP
    if  ($response =~ /^SIP./){
      print "$tstring, $rtime seconds response time, cnt=".$resend_times."|rtt=".$rtime."s;cnt=".$resend_times.";0.5s;1s;0:10; code=".$rcode."\n";
      return 1;
    } 
    else { print "Unknown error: $tstring, $rtime seconds response time, cnt=".$resend_times."|rtt=".$rtime."s;cnt=".$resend_times.";0.5s;1s;0:10; code=".$rcode."\n"; return 0; }
  }
}