#!/usr/bin/perl
=for comment
  Part of AREDN -- Used for creating Amateur Radio Emergency Data Networks
  Copyright (C) 2015 Joe Ayers  ae6xe@arrl.net
  See Contributors file for additional contributors

  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 version 3 of the License.

  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, see <http://www.gnu.org/licenses/>.

  Additional Terms:

  Additional use restrictions exist on the AREDN(TM) trademark and logo.
  See AREDNLicense.txt for more info.

  Attributions to the AREDN Project must be retained in the source code.
  If importing this code into a new or existing project attribution
  to the AREDN project must be added to the source code.

  You must not misrepresent the origin of the material contained within.

  Modified versions must be modified to attribute to the original source
  and be marked in reasonable ways as differentiate it from the original
  version.

=cut

# Joe Ayers AE6XE ae6xe@arrl.net 2015-12-08
# work around Atheros ANI overly attenuating recieve chain with tendency to become stuck
# A receive chain may go deaf at noise prone sites and some neighbors may drop out.
# The wireless driver poorly tunes and treats these neighbors as noise in error.
# This is a workaround until root cause driver updates occur.

$now=`cat /proc/uptime | cut -f1 -d" "`;
chomp $now;

exit 0 unless $now > 119;

$iface = "wlan0" ; # wireless interface
$datfile = "/tmp/rssi.dat";
$logfile = "/tmp/rssi.log";

open(my $lfh, '>>', $logfile) or die "Could not open file $logfile $!";

sub getRSSI
{
  for (keys %rssi)
    {
        delete $rssi{$_};
    }

  open(FILE, "/usr/sbin/iw $iface station dump 2>&1 |") or die "/usr/sbin/iw failed $!";

  $neighborCount = 0;
  while($line = <FILE>)
  {
    if($line =~ /Station (\S+) \(on $iface\)/) { $mac = $1;}
    if($antnum and $line =~ /signal:[ \t]+[-\d]+[ \t]*\[([-\d]+),[ \t]*([-\d]+)/)
    {
      $H = $1;
      $V = $2;
    }

    if ((not $antnum) and $line =~ /signal:[ \t]+[-\d]+[ \t]*\[([-\d]+)\]/)
    {
      $H = $1;
    }
    if ($H)
    {
        if ($H < -95) { $rssi{$mac}{"Hrssi"}=-96 ; }
        else { $rssi{$mac}{"Hrssi"}=$H ; }
        undef $H;
        $neighborCount += 1;
    }
    if ($V)
    {
        if ($V < -95) { $rssi{$mac}{"Vrssi"}=-96 ; }
        else { $rssi{$mac}{"Vrssi"}=$V ; }
        undef $V;
    }
  }
}

sub getChannelScan
{
  $chnum = `uci get wireless.radio0.channel`;
  $chnum += 1;
  if ($chnum == 8 or $chnum == 12 or $chnum == 100 or $chnum == 185) { $chnum -= 2; }
  if ($chnum == 0) { $chnum = 1; }
  $freq = `iw list | grep "\\\[$chnum\\\]" | head -1`;
  $freq =~ /([\d]+)[ \t]+MHz[ \t]+/;
  $freq = $1;
}

$antnum=`iw list | grep "Configured Antennas: TX" | cut -f6 -d" "`;
chomp $antnum;
if ($antnum eq "0x1")
{
  $antnum=0;
}
else
{
  $antnum=1;  # more than one
}

if ( -e $datfile )
{
  open(FILE, "<$datfile") or die "Unable to read \"$datfile\"";

  while($line = <FILE>)
  {
    if ($antnum)
    {
      ($mac, $aveH, $aveV, $stdDevH, $stdDevV, $numS, $last) = split /\|/, $line;
      $rssiHist{$mac}{"aveV"} = $aveV;
      $rssiHist{$mac}{"sdV"} = $stdDevV;
    }
    else
    {
      ($mac, $aveH, $stdDevH, $numS, $last) = split /\|/, $line;
    }
    $rssiHist{$mac}{"aveH"} = $aveH;
    $rssiHist{$mac}{"sdH"} = $stdDevH;
    $rssiHist{$mac}{"num"} = $numS;
    chomp $last;
    $rssiHist{$mac}{"last"} = $last;
  }
  close FILE ;
}

$ofdm_level = `cat /sys/kernel/debug/ieee80211/phy0/ath9k/ani | grep "OFDM LEVEL" | cut -f2 -d: `;
$now=`cat /proc/uptime | cut -f1 -d" "`;
chomp $now;

if ($now < 750 and $now > 119 )
{
  # avoid node going deaf while trying to obtain 'normal' statistics of neighbor strength
  # in first few minutes after boot
  getChannelScan();
  system("/usr/sbin/iw $iface scan freq $freq passive > /dev/null");
}

getRSSI() ;

for (keys %rssi)
{
  if ( $rssiHist{$_} and $now - $rssiHist{$_}{"last"} < 3600 )
  {
    $hit = 0 ;
    $sdH3 = int(3 * $rssiHist{$_}{"sdH"} + .5);
    # is the RSSI attenuated and 3 standard deviations away?   
    if   (abs ($rssiHist{$_}{"aveH"} - $rssi{$_}{"Hrssi"})  > $sdH3) { $hit += 1; }
    if ( $antnum )
    {
      $sdV3 = int(3 * $rssiHist{$_}{"sdV"} + .5);
      if (abs ( $rssiHist{$_}{"aveV"} - $rssi{$_}{"Vrssi"})  >  $sdV3) { $hit += 1; }
    }

    if ($rssiHist{$_}{"num"} > 9 and $ofdm_level <= 3 and $hit > 0)
    { # Overly Attenuated Chain Suspected
      $datestring = localtime();
      if ($antnum)
      {
        print $lfh "$datestring: Attenuated Suspect $_ [$rssi{$_}{'Hrssi'},$rssi{$_}{'Vrssi'}] $rssiHist{$_}{'aveH'} ";
        print $lfh "$rssiHist{$_}{'aveV'} $rssiHist{$_}{'sdH'} $rssiHist{$_}{'sdV'}\n";
      }
      else
      {
        print $lfh "$datestring: Attenuated Suspect $_ [$rssi{$_}{'Hrssi'}] $rssiHist{$_}{'aveH'} $rssiHist{$_}{'sdH'}\n";
      }

      # find strongest signal to compare RSSI before/after reset
      if ( $amac )
      {
	if ($antnum)
        {
          if ($rssi{$amac}{"Hrssi"} < $rssi{$amac}{"Vrssi"} ) { $strong1 = "Vrssi" ;} else {$strong1 = "Hrssi";  }
          if ($rssi{$_}{"Hrssi"} < $rssi{$_}{"Vrssi"} ) { $strong2 = "Vrssi" ;} else {$strong2 = "Hrssi";  }
          if ($rssi{$amac}{$strong1} < $rssi{$_}{$strong2} ) { $amac = $_ ;}
        }
        else
        {
          if ($rssi{$amac}{"Hrssi"} < $rssi{$_}{"Hrssi"} ) { $amac = $_ ;}
        }
      }
      else { $amac = $_ ; }
      next ; # do not update statistics when suspected condition
    }

    # unpdate statistics
    $aveH = (($rssiHist{$_}{"aveH"}*$rssiHist{$_}{"num"})+$rssi{$_}{"Hrssi"}) / ($rssiHist{$_}{"num"} + 1 );
    $sdH = sqrt((($rssiHist{$_}{"num"}-1)*($rssiHist{$_}{"sdH"}**2) +
               (($rssi{$_}{"Hrssi"}-$aveH)*($rssi{$_}{"Hrssi"}-$rssiHist{$_}{"aveH"})))/$rssiHist{$_}{"num"});
    chomp $aveH;
    chomp $sdH;

    if ($antnum)
    {
      $aveV = (($rssiHist{$_}{"aveV"}*$rssiHist{$_}{"num"})+$rssi{$_}{"Vrssi"}) / ($rssiHist{$_}{"num"} + 1 );
      $sdV = sqrt((($rssiHist{$_}{"num"}-1)*($rssiHist{$_}{"sdV"}**2) +
               (($rssi{$_}{"Vrssi"}-$aveV)*($rssi{$_}{"Vrssi"}-$rssiHist{$_}{"aveV"})))/$rssiHist{$_}{"num"});
      chomp $aveV;
      chomp $sdV;
    }

    $rssiHist{$_}{"aveH"} = $aveH;
    $rssiHist{$_}{"sdH"} =  $sdH;
    $rssiHist{$_}{"last"} = $now;
    if ($rssiHist{$_}{"num"} < 60 )
    {
      # keep statistics to 60 sample (minute) moving window
      $rssiHist{$_}{"num"} += 1;
    }
    if ($antnum)
    {
      $rssiHist{$_}{"aveV"} = $aveV;
      $rssiHist{$_}{"sdV"} =  $sdV;
    }
  }
  else
  {  # new neigbor or data too old--restart history
    $rssiHist{$_}{"aveH"} = $rssi{$_}{"Hrssi"};
    $rssiHist{$_}{"sdH"} = 0;
    $rssiHist{$_}{"num"} = 1;
    $rssiHist{$_}{"last"} = $now;
    if ($antnum)
    {
      $rssiHist{$_}{"aveV"} = $rssi{$_}{"Vrssi"};
      $rssiHist{$_}{"sdV"} = 0;
    }
  }
}

if ($amac or not $neighborCount)
{
  getChannelScan();

  if ($amac)
  {
    $datestring = localtime();
    if ($antnum) {print $lfh "$datestring: before $amac [ $rssi{$amac}{'Hrssi'}, $rssi{$amac}{'Vrssi'} ]\n";}
    else         {print $lfh "$datestring: before $amac [ $rssi{$amac}{'Hrssi'}]\n";}
  }

  system("/usr/sbin/iw $iface scan freq $freq passive > /dev/null");

  if ($amac)
  {
    sleep 5;

    $beforeH = $rssi{$amac}{"Hrssi"};
    if ($antnum) { $beforeV = $rssi{$amac}{"Vrssi"}; }

    getRSSI() ;
    $datestring = localtime();
    if ($antnum) {print $lfh "$datestring: after  $amac [ $rssi{$amac}{'Hrssi'}, $rssi{$amac}{'Vrssi'} ]\n";}
    else         {print $lfh "$datestring: after  $amac [ $rssi{$amac}{'Hrssi'}]\n";}

    $falpos = 0;
    if ($antnum)
    {
      if  (abs ( $beforeH - $rssi{$amac}{"Hrssi"} ) <= 2 and
           abs ( $beforeV - $rssi{$amac}{"Vrssi"} ) <= 2 ) { $falpos = 1; }
    }
    elsif (abs ( $beforeH - $rssi{$amac}{"Hrssi"} ) <= 2 ) { $falpos = 1; }

    if ( $falpos )
    {
      # if a false-positive (within 2dB change after a reset), then add data point to statistics
      $aveH = (($rssiHist{$amac}{"aveH"}*$rssiHist{$amac}{"num"})+ $beforeH )
                                                / ($rssiHist{$amac}{"num"} + 1 );
      $sdH = sqrt((($rssiHist{$amac}{"num"}-1)*($rssiHist{$amac}{"sdH"}**2) +
                 (($beforeH-$aveH)*($beforeH-$rssiHist{$amac}{"aveH"})))
                                           /$rssiHist{$amac}{"num"});
      chomp $aveH;
      chomp $sdH;
      $rssiHist{$amac}{"aveH"} = $aveH;
      $rssiHist{$amac}{"sdH"} =  $sdH;

      if ($antnum)
      {
        $aveV = (($rssiHist{$amac}{"aveV"}*$rssiHist{$amac}{"num"})+ $beforeV ) /
                                                    ($rssiHist{$amac}{"num"} + 1 );
        $sdV = sqrt((($rssiHist{$amac}{"num"}-1)*($rssiHist{$amac}{"sdV"}**2) +
                             (($beforeV-$aveV)*($beforeV-$rssiHist{$amac}{"aveV"}))) /
                                                        $rssiHist{$amac}{"num"});
        chomp $aveV;
        chomp $sdV;
        $rssiHist{$amac}{"aveV"} = $aveV;
        $rssiHist{$amac}{"sdV"} =  $sdV;
      }

      if ($rssiHist{$amac}{"num"} < 60 )
      {
        # keep statistics to 60 sample (minute) moving window
        $rssiHist{$amac}{"num"} += 1;
      }
      $rssiHist{$amac}{"last"} = $now + 5 ;

      $datestring = localtime();
      print $lfh "$datestring: $amac Possible valid data point, adding to statistics.\n";
    }
  }
}

close $lfh;

open($dfh, ">$datfile") or die "Unable to create \"$datfile\" $!";
for (keys %rssiHist)
{
  if ($antnum)
  {
    print $dfh "$_|$rssiHist{$_}{'aveH'}|$rssiHist{$_}{'aveV'}|$rssiHist{$_}{'sdH'}|";
    print $dfh "$rssiHist{$_}{'sdV'}|$rssiHist{$_}{'num'}|$rssiHist{$_}{'last'}\n";
  }
  else
  {
    print $dfh "$_|$rssiHist{$_}{'aveH'}|$rssiHist{$_}{'sdH'}|$rssiHist{$_}{'num'}|$rssiHist{$_}{'last'}\n";
  }
}

close $dfh;

# when logfile gets 1k over $MAXSIZE, then chop down
$MAXSIZE = 2**14;
exit 0 unless -s $logfile > $MAXSIZE + 1024;
@ARGV = $logfile;
undef $/;
$^I = "";
while (<>)
{
  substr($_, 0, length() - $MAXSIZE) = "";
  s/.*\n//;
  print;
}