#! /usr/bin/perl -w

# monitor http,https,smtp on remote servers.

use strict;
use LWP::Simple;

my ($http,$https,$smtp);
chomp (my $hostname = `/bin/uname -n`);

$http = {
        "ja.hallolucy.net"            => 'http://ja.hallolucy.net',
        "www.coolwebsite.com" => 'http://www.coolwebsite.com',
        "notsocoolwebsite.com" => 'http://notsocoolwebsite.com',
        };

$https = {
        "eat.atjoes.org"                   => 'https://eat.atjoes.org',
        "secure.bigtopstuff.com"    => 'https://secure.bigtopstuff.com',
        "www.iliketoshophere.com" => 'https://www.iliketoshophere.com',
        };

$smtp = {
        "mail.atsomewhere.com"          => 'mail.atsomewhere.com',
        "imap.overheretoo.net"          => 'imap.overheretoo.net',
        };

resolve_host($http,$https,$smtp);

# --------------------------------
# SUBROUTINES
# --------------------------------

sub resolve_host {
  my (@hosts) = @_;
  my (%records,$record,$notfound,$matches,$proto,$count);
  $notfound = '\s{1}not\s{1}found\:';
  $matches  = '^(:?\S+).*?(\d+\.\d+\.\d+\.\d+)$';
  $count    = @hosts;

  for $proto (@hosts) {
    $count--;
    for (keys %{$proto}) {
      chomp($record = `/usr/bin/host $_`);
      if ($record =~ /$notfound/o) {
        email_resolution_error($_,$hostname);

      } else {
        if ($count == 0) {
          scan_mail($_,$2,'[SMTP]') if $record =~ /$matches/o;

        } elsif ($count == 1) {
          scan_web($proto->{$_},'[SSL]');

        } elsif ($count == $#hosts) {
          scan_web($proto->{$_},'[WEB]');

        } else {
          die "Was args passed proper? [ex: resolve_host(\$http,\$https,\$smtp)]: $!\n";
        }
      }
    }
  }
}

sub scan_web {
  my ($hosts,$proto) = @_;
  email_connection_error($_,$proto,$hostname) unless head($hosts);
}

sub scan_mail {
  my ($rserver,$ip,$proto) = @_;
  my $port = "25";
  my $result;
  $result = `/usr/bin/nmap -P0 -p$port -oG - $ip | grep 'Status: Up'`;
  email_connection_error($rserver,$proto,$hostname) if $result;
}

sub email_resolution_error {
  my ($rnode,$hostname) = @_;

  open(SENDMAIL, "|/usr/lib/sendmail -oi -t")
        or die "Cannot fork for sendmail: $!\n";

    print SENDMAIL "From: multimon SOS <nobody\@${hostname}>\n";
    print SENDMAIL "To: SysAdmin <someone\@somewhere.com>\n";
    print SENDMAIL "Cc: emergency\@mobilepager.com\n";
    print SENDMAIL "Subject: [DNS]: $rnode cannot be resolved!\n";
    print SENDMAIL "\n";
    print SENDMAIL "Email generated by the multimon script on $hostname\n";
    print SENDMAIL "[DNS]: $rnode cannot be resolved!\n";

  close(SENDMAIL) or warn "Oops, sendmail did not close nicely";
}

sub email_connection_error { 
  my ($rserver,$proto,$hostname) = @_;

  open(SENDMAIL, "|/usr/lib/sendmail -oi -t")
        or die "Cannot fork for sendmail: $!\n";
    
    print SENDMAIL "From: multimon SOS <nobody\@${hostname}>\n";
    print SENDMAIL "To: SysAdmin <someone\@somewhere.com>\n";
    print SENDMAIL "Cc: emergency\@mobilepager.com\n";
    print SENDMAIL "Subject: $proto: $rserver cannot be contacted!\n";
    print SENDMAIL "\n";
    print SENDMAIL "Email generated by the multimon script on $hostname\n";
    print SENDMAIL "$proto: $rserver cannot be contacted!\n";

  close(SENDMAIL) or warn "Oops, sendmail did not close nicely";
}