<?php

// $filter = array(v4, v6, file('/srv/http/vhosts/eckner.net/ddns/ip-filters'))
// $x \in array($token, $token.$filter foreach $filter with match):
// $x.ddns.eckner.net (all)

  function lifetime($addr) {
    if (filter_var($addr, FILTER_VALIDATE_IP, FILTER_FLAG_IPV4)) {
      $addrTeile = explode('.', $addr);
      if (($addrTeile[0] == '10') ||
         (($addrTeile[0] == '192') && ($addrTeile[1] == '168')) ||
         (($addrTeile[0] == '172') && ($addrTeile[1] >= 16) && ($addrTeile[1] < 32)))
        return '7200';
    };
    return '120';
  };

  function convert_ipv6_address_part_to_reverse_record_part(&$part) {
    while (strlen($part)<4)
      $part = '0' . $part;
    $part = str_split($part);
    $part = array_reverse($part);
    $part = implode('.', $part);
  };

  function reverse_ipv6_address($addr) {
    $addr_Teile = array();
    while (count($addr_Teile) < 8) {
      $addr_Teile = explode(':', $addr);
      $addr = str_replace('::',':0::',$addr);
    }
    array_walk($addr_Teile, 'convert_ipv6_address_part_to_reverse_record_part');
    $addr_Teile = array_reverse($addr_Teile);
    return implode('.', $addr_Teile);
  };

  function reverse_entry($addr) {
    if (filter_var($addr, FILTER_VALIDATE_IP, FILTER_FLAG_IPV4)) {
      $addrTeile = explode('.', $addr);
      $lp = array_pop($addrTeile);
      $subNet = implode('.', $addrTeile);
      array_push($addrTeile, $lp);
      $addrTeile = array_reverse($addrTeile);
      if (($subNet == '10.0.2') ||
          ($subNet == '192.168.0') ||
          ($subNet == '192.168.1'))
        return implode('.',$addrTeile).'.in-addr.arpa.';
    } elseif (filter_var($addr, FILTER_VALIDATE_IP, FILTER_FLAG_IPV6)) {
      $reversed_address = reverse_ipv6_address($addr);
      if (stripos(implode('.',array_reverse(explode('.',$reversed_address))),'2.a.0.1.0.0.d.0.f.6.c.e.')===0)
        return $reversed_address.'.ip6.arpa.';
    };
    return NULL;
  };

  function reverse_zone($addr) {
    if (filter_var($addr, FILTER_VALIDATE_IP, FILTER_FLAG_IPV4)) {
      $addrTeile = explode('.', $addr);
      array_pop($addrTeile);
      $addrTeile = array_reverse($addrTeile);
      return implode('.',$addrTeile).'.in-addr.arpa.';
    } elseif (filter_var($addr, FILTER_VALIDATE_IP, FILTER_FLAG_IPV6)) {
      $reversed_address = reverse_ipv6_address($addr);
      if (stripos(implode('.',array_reverse(explode('.',$reversed_address))),'2.a.0.1.0.0.d.0.f.6.c.e.')===0)
        return 'e.c.6.f.0.d.0.0.1.0.a.2.ip6.arpa.';
    };
    return NULL;
  };

  // invalid syntax?
  if ((!array_key_exists('i', $_GET)) ||
      (strlen($_GET['i']) != 64) ||
      (preg_match('@^[0-9A-Za-z]{64}$@', $_GET['i']) != 1))
    die();

  $line = preg_grep('@^' . $_GET['i'] . ' @', file('/srv/http/vhosts/eckner.net/ddns/tokens'));

  // unknown token?
  if (count($line) != 1)
    die();

  $domain = substr(explode(' ', implode('', $line))[1], 0, -1);
  if (array_key_exists('address', $_GET))
    $ips = explode(',', $_GET['address']);
  else
    $ips[0] = 'auto';

  foreach ($ips as $i => $ip)
    if ($ip == 'auto')
      $ips[$i] = $_SERVER['REMOTE_ADDR'];

  $ips = array_unique($ips);

  $hasRrType = array();
  $rrTypes = array();
  $filterMatches = array();

  $filters = array();
  foreach (file('/srv/http/vhosts/eckner.net/ddns/ip-filters') as $filterLine) {
    if (substr($filterLine, 0, 1) == '#')
      continue;
    $filter = explode(' ', $filterLine);
    if (count($filter) < 2)
      continue;
    $filters[] = array(
      'name' => $filter[0],
      'regex' => substr($filter[1], 0, -1)
    );
  }

  foreach ($ips as $i => $ip) {
    $filterMatches[$i] = array();
    if (filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_IPV4)) {
      $rrTypes[$i] = 'A';
      $hasRrType['A'] = 1;
      $filterMatches[$i][] = 'v4';
    }
    elseif (filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_IPV6)) {
      $rrTypes[$i] = 'AAAA';
      $hasRrType['AAAA'] = 1;
      $filterMatches[$i][] = 'v6';
    }
    else
      die();
    foreach ($filters as $filter) {
      if (preg_match('@' . $filter['regex'] . '@', $ip) == 1)
        $filterMatches[$i][] = $filter['name'];
      else
        $filterMatches[$i][] = 'non-' . $filter['name'];
    }
    $filterMatches[$i] = array_unique($filterMatches[$i]);
  }

  $updateCommand = "zone ddns.eckner.net.\n";
  $logContent = '';

  foreach ($hasRrType as $rrType => $dummy) {
    // delete old record if existing
    $updateCommand .=
      "prereq yxrrset " . $domain . ".ddns.eckner.net IN " . $rrType . "\n" .
      "update delete " . $domain . ".ddns.eckner.net IN " . $rrType . "\n" .
      "send\n";
    if ($rrType == 'A')
      $updateCommand .=
        "prereq yxrrset " . $domain . ".v4.ddns.eckner.net IN " . $rrType . "\n" .
        "update delete " . $domain . ".v4.ddns.eckner.net IN " . $rrType . "\n" .
        "send\n";
    else
      $updateCommand .=
        "prereq yxrrset " . $domain . ".v6.ddns.eckner.net IN " . $rrType . "\n" .
        "update delete " . $domain . ".v6.ddns.eckner.net IN " . $rrType . "\n" .
        "send\n";
    foreach ($filters as $filter) {
      foreach (array('', 'non-') as $filter_prefix) {
        $updateCommand .=
          "prereq yxrrset " . $domain . "." . $filter_prefix . $filter['name'] . ".ddns.eckner.net IN " . $rrType . "\n" .
          "update delete " . $domain . "." . $filter_prefix . $filter['name'] . ".ddns.eckner.net IN " . $rrType . "\n" .
          "send\n";
      }
    }
  }
  // set new records no matter what
  foreach ($ips as $i => $ip) {
    $updateCommand .=
      "update add " . $domain . ".ddns.eckner.net. " . lifetime($ip) . " IN " . $rrTypes[$i] . " " . $ip . "\n";
    $logContent .=
      date('Y-m-d H:i:s') . ' ' . $domain . ' ' . $ip . "\n";
    foreach ($filterMatches[$i] as $filter) {
      $updateCommand .=
        "update add " . $domain . "." . $filter . ".ddns.eckner.net. " . lifetime($ip) . " IN " . $rrTypes[$i] . " " . $ip . "\n";
      $logContent .=
        date('Y-m-d H:i:s') . ' ' . $domain . '.' . $filter . ' ' . $ip . "\n";
    }
  }
  $updateCommand .=
    "send\n";
  foreach ($ips as $i => $ip) {
    $reverse_entry = reverse_entry($ip);
    if (!$reverse_entry)
      continue;
    $updateCommand .=
      "zone ".reverse_zone($ip)."\n";
    // delete old record if existing
    $updateCommand .=
      "prereq yxrrset " . $reverse_entry . " IN PTR\n" .
      "update delete " . $reverse_entry . " IN PTR\n" .
      "send\n";
    // set new records no matter what
    $updateCommand .=
      "update add " . $reverse_entry . " " . lifetime($ip) . " IN PTR " . $domain . ".ddns.eckner.net.\n" .
      "send\n";
  }

  $aliasess = preg_grep('@ ' . $domain . '\b@', file('/srv/http/vhosts/eckner.net/ddns/aliases'));
  if (count($aliasess)) {
    $pin = popen(
      'dig @127.0.0.1 ddns.eckner.net AXFR' .
      ' | sed "s/^\([^;.[:space:]]\+\)\.ddns\.eckner\.net\.\s\+\([0-9]\+\)\s\+IN\s\+\(AAAA\|A\)\s\+\(\S\+\)$/\1 \2 \3 \4/;t;d"',
      'r');
    if ($pin === FALSE)
      die_http(500, 'Internal Server Error', 'Failed to get Zone.');
    while (!feof($pin))
      $zone_file .= fread($pin, 1024);
    $zone_file = explode("\n", trim($zone_file));
    pclose($pin);
    foreach($aliasess as $aliases) {
      $aliases = explode(' ', trim($aliases));
      $alias = array_shift($aliases);
      $updateCommand .=
        "zone ddns.eckner.net.\n" .
        "prereq yxrrset " . $alias . ".ddns.eckner.net.\n" .
        "update delete " . $alias . ".ddns.eckner.net.\n" .
        "send\n";
      foreach($aliases as $representative) {
        foreach($zone_file as $zone_file_entry) {
          if (preg_match('/^'.$representative.' ([0-9]+) (AAAA|A) (\S+)$/', $zone_file_entry, $match)) {
            $updateCommand .=
              "update add " . $alias . ".ddns.eckner.net. " . $match[1] . " IN " . $match[2] . " " . $match[3] . "\n";
          }
        }
      }
      $updateCommand .=
        "send\n";
    }
  }

  // actually do something
  $pin = popen('nsupdate -l', 'w');
  if ($pin === FALSE)
    die_http(500, 'Internal Server Error', 'Failed to update Zone.');

  fwrite($pin, $updateCommand);
  pclose($pin);

  file_put_contents('/srv/http/vhosts/eckner.net/ddns/log', $logContent, FILE_APPEND | LOCK_EX);

  print "updated ips for domain \"" . $domain . ".ddns.eckner.net\": " . implode($ips,", ") . "\n";