#!rsc
# RouterOS script: daily-psk
# Copyright (c) 2013-2019 Christian Hesse <mail@eworm.de>
#
# update daily PSK (pre shared key)

:global Identity;
:global DailyPskMatchComment;

:global SendNotification;

:local Seen [ :toarray "" ];

# return pseudo-random string for PSK
:local GeneratePSK do={
  :local Date [ :tostr $1 ];

  :global DailyPskSecrets;

  :local Months { "jan"; "feb"; "mar"; "apr"; "may"; "jun";
                  "jul"; "aug"; "sep"; "oct"; "nov"; "dec" };
  :local MonthTbl { 0; 3; 3; 6; 1; 4; 6; 2; 5; 0; 3; 5 };

  :local MonthStr [ :pick $Date 0 3 ];
  :local Month;
  :local Day [ :pick $Date 4 6 ];
  :local Century [ :pick $Date 7 9 ];
  :local Year [ :pick $Date 9 11 ];

  # get numeric value for month
  :for MIndex from=0 to=[ :len $Months ] do={
    :if ([ :pick $Months $MIndex ] = $MonthStr) do={
      :set Month $MIndex;
    }
  }

  # calculate day of week
  :local Sum 0;
  :set Sum ($Sum + (2 * (3 - ($Century - (($Century / 4) * 4)))));
  :set Sum ($Sum + ($Year / 4));
  :set Sum ($Sum + $Year + $Day);
  :set Sum ($Sum + $Month);
  :set Sum ($Sum - (($Sum / 7) * 7));

  :local Return ([ :pick [ :pick $DailyPskSecrets 0 ] ($Day - 1) ] . \
    [ :pick [ :pick $DailyPskSecrets 1 ] $Month ] . \
    [ :pick [ :pick $DailyPskSecrets 2 ] $Sum ]);

  :return $Return;
}

:local Date [ / system clock get date ];
:local NewPsk [ $GeneratePSK $Date ];

:foreach AccList in=[ / interface wireless access-list find where comment~$DailyPskMatchComment ] do={
  :local IntName [ / interface wireless access-list get $AccList interface ];
  :local Interface [ / interface wireless find where name=$IntName disabled=no ];
  :local Ssid [ / interface wireless get $IntName ssid ];
  :local OldPsk [ / interface wireless access-list get $AccList private-pre-shared-key ];
  :local Skip 0;

  :if ($NewPsk != $OldPsk) do={
    :log info ("Updating daily PSK for " . $IntName . " to " . $NewPsk . " (was " . $OldPsk . ")");
    / interface wireless access-list set $AccList private-pre-shared-key=$NewPsk;

    :if ([ :len $Interface ] = 1) do={
      :foreach SeenSsid in=$Seen do={
        :if ($SeenSsid = $Ssid) do={
          :log debug ("Already sent a mail for SSID " . $Ssid . ", skipping.");
          :set Skip 1;
        }
      }

      :if ($Skip = 0) do={
        :set Seen ($Seen, $Ssid);

        :local Url ("https://www.eworm.de/cgi-bin/cqrlogo-wifi.cgi" . \
            "?scale=8&level=1&ssid=" . $Ssid . "&pass=" . $NewPsk);
        :local Attach "qrcode-daily.png";

        :do {
          / tool fetch mode=https check-certificate=yes-without-crl \
              $Url dst-path=$Attach;
        } on-error={
          :set Attach "";
        }

        $SendNotification ("daily PSK " . $Ssid) \
          ("This is the daily PSK on " . $Identity . ":\n\n" . \
            "SSID: " . $Ssid . "\n" . \
            "PSK:  " . $NewPsk . "\n" . \
            "Date: " . $Date . "\n\n" . \
            $Url) $Attach;
      }
    } else={
      :log debug ("Missing active interface " . $IntName . " for access list entry.");
    }
  }
}