xref: /dports/dns/powerdns/pdns-4.5.2/pdns/lua-record.cc

#include <thread>
#include <future>
#include <mutex>
#include <boost/format.hpp>
#include <utility>
#include "version.hh"
#include "ext/luawrapper/include/LuaContext.hpp"
#include "lua-auth4.hh"
#include "sstuff.hh"
#include "minicurl.hh"
#include "ueberbackend.hh"
#include "dnsrecords.hh"
#include "dns_random.hh"
#include "common_startup.hh"
#include "../modules/geoipbackend/geoipinterface.hh" // only for the enum

/* to do:
   block AXFR unless TSIG, or override

   investigate IPv6

   check the wildcard 'no cache' stuff, we may get it wrong

   ponder ECS scopemask setting

   ponder netmask tree from file for huge number of netmasks

   unify ifurlup/ifportup
      add attribute for certificate check
   add list of current monitors
      expire them too?

   pool of UeberBackends?

   Pool checks ?
 */

extern int  g_luaRecordExecLimit;

using iplist_t = vector<pair<int, string> >;
using wiplist_t = std::unordered_map<int, string>;
using ipunitlist_t = vector<pair<int, iplist_t> >;
using opts_t = std::unordered_map<string,string>;

class IsUpOracle
{
private:
  struct CheckDesc
  {
    ComboAddress rem;
    string url;
    opts_t opts;
    bool operator<(const CheckDesc& rhs) const
    {
      std::map<string,string> oopts, rhsoopts;
      for(const auto& m : opts)
        oopts[m.first]=m.second;
      for(const auto& m : rhs.opts)
        rhsoopts[m.first]=m.second;

      return std::make_tuple(rem, url, oopts) <
        std::make_tuple(rhs.rem, rhs.url, rhsoopts);
    }
  };
  struct CheckState
  {
    CheckState(time_t _lastAccess): lastAccess(_lastAccess) {}
    /* current status */
    std::atomic<bool> status{false};
    /* first check ? */
    std::atomic<bool> first{true};
    /* last time the status was accessed */
    std::atomic<time_t> lastAccess{0};
  };

  ReadWriteLock d_lock;
public:
  IsUpOracle()
  {
  }
  ~IsUpOracle()
  {
  }
  bool isUp(const ComboAddress& remote, const opts_t& opts);
  bool isUp(const ComboAddress& remote, const std::string& url, const opts_t& opts);
  bool isUp(const CheckDesc& cd);

private:
  void checkURL(const CheckDesc& cd, const bool status, const bool first = false)
  {
    try {
      int timeout = 2;
      if (cd.opts.count("timeout")) {
        timeout = std::atoi(cd.opts.at("timeout").c_str());
      }
      string useragent = productName();
      if (cd.opts.count("useragent")) {
        useragent = cd.opts.at("useragent");
      }
      MiniCurl mc(useragent);

      string content;
      if (cd.opts.count("source")) {
        ComboAddress src(cd.opts.at("source"));
        content=mc.getURL(cd.url, &cd.rem, &src, timeout);
      }
      else {
        content=mc.getURL(cd.url, &cd.rem, nullptr, timeout);
      }
      if (cd.opts.count("stringmatch") && content.find(cd.opts.at("stringmatch")) == string::npos) {
        throw std::runtime_error(boost::str(boost::format("unable to match content with `%s`") % cd.opts.at("stringmatch")));
      }
      if(!status) {
        g_log<<Logger::Info<<"LUA record monitoring declaring "<<cd.rem.toString()<<" UP for URL "<<cd.url<<"!"<<endl;
      }
      setUp(cd);
    }
    catch(std::exception& ne) {
      if(status || first)
        g_log<<Logger::Info<<"LUA record monitoring declaring "<<cd.rem.toString()<<" DOWN for URL "<<cd.url<<", error: "<<ne.what()<<endl;
      setDown(cd);
    }
  }
  void checkTCP(const CheckDesc& cd, const bool status, const bool first = false) {
    try {
      int timeout = 2;
      if (cd.opts.count("timeout")) {
        timeout = std::atoi(cd.opts.at("timeout").c_str());
      }
      Socket s(cd.rem.sin4.sin_family, SOCK_STREAM);
      ComboAddress src;
      s.setNonBlocking();
      if (cd.opts.count("source")) {
        src = ComboAddress(cd.opts.at("source"));
        s.bind(src);
      }
      s.connect(cd.rem, timeout);
      if (!status) {
        g_log<<Logger::Info<<"Lua record monitoring declaring TCP/IP "<<cd.rem.toStringWithPort()<<" ";
        if(cd.opts.count("source"))
          g_log<<"(source "<<src.toString()<<") ";
        g_log<<"UP!"<<endl;
      }
      setUp(cd);
    }
    catch (const NetworkError& ne) {
      if(status || first) {
        g_log<<Logger::Info<<"Lua record monitoring declaring TCP/IP "<<cd.rem.toStringWithPort()<<" DOWN: "<<ne.what()<<endl;
      }
      setDown(cd);
    }
  }
  void checkThread()
  {
    while (true)
    {
      std::chrono::system_clock::time_point checkStart = std::chrono::system_clock::now();
      std::vector<std::future<void>> results;
      std::vector<CheckDesc> toDelete;
      {
        ReadLock lock{&d_lock}; // make sure there's no insertion
        for (auto& it: d_statuses) {
          auto& desc = it.first;
          auto& state = it.second;

          if (desc.url.empty()) { // TCP
            results.push_back(std::async(std::launch::async, &IsUpOracle::checkTCP, this, desc, state->status.load(), state->first.load()));
          } else { // URL
            results.push_back(std::async(std::launch::async, &IsUpOracle::checkURL, this, desc, state->status.load(), state->first.load()));
          }
          if (std::chrono::system_clock::from_time_t(state->lastAccess) < (checkStart - std::chrono::seconds(g_luaHealthChecksExpireDelay))) {
            toDelete.push_back(desc);
          }
        }
      }
      // we can release the lock as nothing will be deleted
      for (auto& future: results) {
        future.wait();
      }
      if (!toDelete.empty()) {
        WriteLock lock{&d_lock};
        for (auto& it: toDelete) {
          d_statuses.erase(it);
        }
      }
      std::this_thread::sleep_until(checkStart + std::chrono::seconds(g_luaHealthChecksInterval));
    }
  }

  typedef map<CheckDesc, std::unique_ptr<CheckState>> statuses_t;
  statuses_t d_statuses;

  std::unique_ptr<std::thread> d_checkerThread;

  void setStatus(const CheckDesc& cd, bool status)
  {
    ReadLock lock{&d_lock};
    auto& state = d_statuses[cd];
    state->status = status;
    if (state->first) {
      state->first = false;
    }
  }

  void setDown(const ComboAddress& rem, const std::string& url=std::string(), const opts_t& opts = opts_t())
  {
    CheckDesc cd{rem, url, opts};
    setStatus(cd, false);
  }

  void setUp(const ComboAddress& rem, const std::string& url=std::string(), const opts_t& opts = opts_t())
  {
    CheckDesc cd{rem, url, opts};

    setStatus(cd, true);
  }

  void setDown(const CheckDesc& cd)
  {
    setStatus(cd, false);
  }

  void setUp(const CheckDesc& cd)
  {
    setStatus(cd, true);
  }
};

bool IsUpOracle::isUp(const CheckDesc& cd)
{
  if (!d_checkerThread) {
    d_checkerThread = std::unique_ptr<std::thread>(new std::thread(&IsUpOracle::checkThread, this));
  }
  time_t now = time(nullptr);
  {
    ReadLock lock{&d_lock};
    auto iter = d_statuses.find(cd);
    if (iter != d_statuses.end()) {
      iter->second->lastAccess = now;
      return iter->second->status;
    }
  }
  // try to parse options so we don't insert any malformed content
  if (cd.opts.count("source")) {
    ComboAddress src(cd.opts.at("source"));
  }
  {
    WriteLock lock{&d_lock};
    // Make sure we don't insert new entry twice now we have the lock
    if (d_statuses.find(cd) == d_statuses.end()) {
      d_statuses[cd] = std::unique_ptr<CheckState>(new CheckState{now});
    }
  }
  return false;
}

bool IsUpOracle::isUp(const ComboAddress& remote, const opts_t& opts)
{
  CheckDesc cd{remote, "", opts};
  return isUp(cd);
}

bool IsUpOracle::isUp(const ComboAddress& remote, const std::string& url, const opts_t& opts)
{
  CheckDesc cd{remote, url, opts};
  return isUp(cd);
}

IsUpOracle g_up;
namespace {
template<typename T, typename C>
bool doCompare(const T& var, const std::string& res, const C& cmp)
{
  if(auto country = boost::get<string>(&var))
    return cmp(*country, res);

  auto countries=boost::get<vector<pair<int,string> > >(&var);
  for(const auto& country : *countries) {
    if(cmp(country.second, res))
      return true;
  }
  return false;
}
}


static std::string getGeo(const std::string& ip, GeoIPInterface::GeoIPQueryAttribute qa)
{
  static bool initialized;
  extern std::function<std::string(const std::string& ip, int)> g_getGeo;
  if(!g_getGeo) {
    if(!initialized) {
      g_log<<Logger::Error<<"LUA Record attempted to use GeoIPBackend functionality, but backend not launched"<<endl;
      initialized=true;
    }
    return "unknown";
  }
  else
    return g_getGeo(ip, (int)qa);
}

static ComboAddress pickrandom(const vector<ComboAddress>& ips)
{
  if (ips.empty()) {
    throw std::invalid_argument("The IP list cannot be empty");
  }
  return ips[dns_random(ips.size())];
}

static ComboAddress hashed(const ComboAddress& who, const vector<ComboAddress>& ips)
{
  if (ips.empty()) {
    throw std::invalid_argument("The IP list cannot be empty");
  }
  ComboAddress::addressOnlyHash aoh;
  return ips[aoh(who) % ips.size()];
}


static ComboAddress pickwrandom(const vector<pair<int,ComboAddress> >& wips)
{
  if (wips.empty()) {
    throw std::invalid_argument("The IP list cannot be empty");
  }
  int sum=0;
  vector<pair<int, ComboAddress> > pick;
  for(auto& i : wips) {
    sum += i.first;
    pick.push_back({sum, i.second});
  }
  int r = dns_random(sum);
  auto p = upper_bound(pick.begin(), pick.end(), r, [](int rarg, const decltype(pick)::value_type& a) { return rarg < a.first; });
  return p->second;
}

static ComboAddress pickwhashed(const ComboAddress& bestwho, vector<pair<int,ComboAddress> >& wips)
{
  if (wips.empty()) {
    return ComboAddress();
  }
  int sum=0;
  vector<pair<int, ComboAddress> > pick;
  for(auto& i : wips) {
    sum += i.first;
    pick.push_back({sum, i.second});
  }
  if (sum == 0) {
    /* we should not have any weight of zero, but better safe than sorry */
    return ComboAddress();
  }
  ComboAddress::addressOnlyHash aoh;
  int r = aoh(bestwho) % sum;
  auto p = upper_bound(pick.begin(), pick.end(), r, [](int rarg, const decltype(pick)::value_type& a) { return rarg < a.first; });
  return p->second;
}

static bool getLatLon(const std::string& ip, double& lat, double& lon)
{
  string inp = getGeo(ip, GeoIPInterface::Location);
  if(inp.empty())
    return false;
  lat=atof(inp.c_str());
  auto pos=inp.find(' ');
  if(pos != string::npos)
    lon=atof(inp.c_str() + pos);
  return true;
}

static bool getLatLon(const std::string& ip, string& loc)
{
  int latdeg, latmin, londeg, lonmin;
  double latsec, lonsec;
  char lathem='X', lonhem='X';

  double lat = 0, lon = 0;
  if(!getLatLon(ip, lat, lon))
    return false;

  if(lat > 0) {
    lathem='N';
  }
  else {
    lat = -lat;
    lathem='S';
  }

  if(lon > 0) {
    lonhem='E';
  }
  else {
    lon = -lon;
    lonhem='W';
  }

  /*
    >>> deg = int(R)
    >>> min = int((R - int(R)) * 60.0)
    >>> sec = (((R - int(R)) * 60.0) - min) * 60.0
    >>> print("{}º {}' {}\"".format(deg, min, sec))
  */


  latdeg = lat;
  latmin = (lat - latdeg)*60.0;
  latsec = (((lat - latdeg)*60.0) - latmin)*60.0;

  londeg = lon;
  lonmin = (lon - londeg)*60.0;
  lonsec = (((lon - londeg)*60.0) - lonmin)*60.0;

  // 51 59 00.000 N 5 55 00.000 E 4.00m 1.00m 10000.00m 10.00m

  boost::format fmt("%d %d %d %c %d %d %d %c 0.00m 1.00m 10000.00m 10.00m");

  loc= (fmt % latdeg % latmin % latsec % lathem % londeg % lonmin % lonsec % lonhem ).str();
  return true;
}

static ComboAddress pickclosest(const ComboAddress& bestwho, const vector<ComboAddress>& wips)
{
  if (wips.empty()) {
    throw std::invalid_argument("The IP list cannot be empty");
  }
  map<double,vector<ComboAddress> > ranked;
  double wlat=0, wlon=0;
  getLatLon(bestwho.toString(), wlat, wlon);
  //        cout<<"bestwho "<<wlat<<", "<<wlon<<endl;
  vector<string> ret;
  for(const auto& c : wips) {
    double lat=0, lon=0;
    getLatLon(c.toString(), lat, lon);
    //          cout<<c.toString()<<": "<<lat<<", "<<lon<<endl;
    double latdiff = wlat-lat;
    double londiff = wlon-lon;
    if(londiff > 180)
      londiff = 360 - londiff;
    double dist2=latdiff*latdiff + londiff*londiff;
    //          cout<<"    distance: "<<sqrt(dist2) * 40000.0/360<<" km"<<endl; // length of a degree
    ranked[dist2].push_back(c);
  }
  return ranked.begin()->second[dns_random(ranked.begin()->second.size())];
}

static std::vector<DNSZoneRecord> lookup(const DNSName& name, uint16_t qtype, int zoneid)
{
  static UeberBackend ub;
  static std::mutex mut;
  std::lock_guard<std::mutex> lock(mut);
  ub.lookup(QType(qtype), name, zoneid);
  DNSZoneRecord dr;
  vector<DNSZoneRecord> ret;
  while(ub.get(dr)) {
    ret.push_back(dr);
  }
  return ret;
}

static std::string getOptionValue(const boost::optional<std::unordered_map<string, string>>& options, const std::string &name, const std::string &defaultValue)
{
  string selector=defaultValue;
  if(options) {
    if(options->count(name))
      selector=options->find(name)->second;
  }
  return selector;
}

static vector<ComboAddress> useSelector(const std::string &selector, const ComboAddress& bestwho, const vector<ComboAddress>& candidates)
{
  vector<ComboAddress> ret;

  if(selector=="all")
    return candidates;
  else if(selector=="random")
    ret.emplace_back(pickrandom(candidates));
  else if(selector=="pickclosest")
    ret.emplace_back(pickclosest(bestwho, candidates));
  else if(selector=="hashed")
    ret.emplace_back(hashed(bestwho, candidates));
  else {
    g_log<<Logger::Warning<<"LUA Record called with unknown selector '"<<selector<<"'"<<endl;
    ret.emplace_back(pickrandom(candidates));
  }

  return ret;
}

static vector<string> convIpListToString(const vector<ComboAddress> &comboAddresses)
{
  vector<string> ret;

  ret.reserve(comboAddresses.size());
  for (const auto& c : comboAddresses) {
    ret.emplace_back(c.toString());
  }

  return ret;
}

static vector<ComboAddress> convIplist(const iplist_t& src)
{
  vector<ComboAddress> ret;

  for(const auto& ip : src) {
    ret.emplace_back(ip.second);
  }

  return ret;
}

static vector<pair<int, ComboAddress> > convWIplist(const std::unordered_map<int, wiplist_t >& src)
{
  vector<pair<int,ComboAddress> > ret;

  ret.reserve(src.size());
  for(const auto& i : src) {
    ret.emplace_back(atoi(i.second.at(1).c_str()), ComboAddress(i.second.at(2)));
  }

  return ret;
}

static thread_local unique_ptr<AuthLua4> s_LUA;
bool g_LuaRecordSharedState;

typedef struct AuthLuaRecordContext
{
  ComboAddress          bestwho;
  DNSName               qname;
  DNSName               zone;
  int                   zoneid;
} lua_record_ctx_t;

static thread_local unique_ptr<lua_record_ctx_t> s_lua_record_ctx;

static void setupLuaRecords()
{
  LuaContext& lua = *s_LUA->getLua();

  lua.writeFunction("latlon", []() {
      double lat = 0, lon = 0;
      getLatLon(s_lua_record_ctx->bestwho.toString(), lat, lon);
      return std::to_string(lat)+" "+std::to_string(lon);
    });
  lua.writeFunction("latlonloc", []() {
      string loc;
      getLatLon(s_lua_record_ctx->bestwho.toString(), loc);
      return loc;
  });
  lua.writeFunction("closestMagic", []() {
      vector<ComboAddress> candidates;
      // Getting something like 192-0-2-1.192-0-2-2.198-51-100-1.example.org
      for(auto l : s_lua_record_ctx->qname.getRawLabels()) {
        boost::replace_all(l, "-", ".");
        try {
          candidates.emplace_back(l);
        } catch (const PDNSException& e) {
          // no need to continue as we most likely reached the end of the ip list
          break ;
        }
      }
      return pickclosest(s_lua_record_ctx->bestwho, candidates).toString();
    });
  lua.writeFunction("latlonMagic", [](){
      auto labels= s_lua_record_ctx->qname.getRawLabels();
      if(labels.size()<4)
        return std::string("unknown");
      double lat = 0, lon = 0;
      getLatLon(labels[3]+"."+labels[2]+"."+labels[1]+"."+labels[0], lat, lon);
      return std::to_string(lat)+" "+std::to_string(lon);
    });


  lua.writeFunction("createReverse", [](string format, boost::optional<std::unordered_map<string,string>> e){
      try {
        auto labels = s_lua_record_ctx->qname.getRawLabels();
        if(labels.size()<4)
          return std::string("unknown");

        vector<ComboAddress> candidates;

        // so, query comes in for 4.3.2.1.in-addr.arpa, zone is called 2.1.in-addr.arpa
        // e["1.2.3.4"]="bert.powerdns.com" then provides an exception
        if(e) {
          ComboAddress req(labels[3]+"."+labels[2]+"."+labels[1]+"."+labels[0], 0);
          const auto& uom = *e;
          for(const auto& c : uom)
            if(ComboAddress(c.first, 0) == req)
              return c.second;
        }
        boost::format fmt(format);
        fmt.exceptions( boost::io::all_error_bits ^ ( boost::io::too_many_args_bit | boost::io::too_few_args_bit )  );
        fmt % labels[3] % labels[2] % labels[1] % labels[0];

        fmt % (labels[3]+"-"+labels[2]+"-"+labels[1]+"-"+labels[0]);

        boost::format fmt2("%02x%02x%02x%02x");
        for(int i=3; i>=0; --i)
          fmt2 % atoi(labels[i].c_str());

        fmt % (fmt2.str());

        return fmt.str();
      }
      catch(std::exception& ex) {
        g_log<<Logger::Error<<"error: "<<ex.what()<<endl;
      }
      return std::string("error");
    });
  lua.writeFunction("createForward", []() {
      static string allZerosIP("0.0.0.0");
      DNSName rel=s_lua_record_ctx->qname.makeRelative(s_lua_record_ctx->zone);
      // parts is something like ["1", "2", "3", "4", "static"] or
      // ["1", "2", "3", "4"] or ["ip40414243", "ip-addresses", ...]
      auto parts = rel.getRawLabels();
      // Yes, this still breaks if an 1-2-3-4.XXXX is nested too deeply...
      if(parts.size()>=4) {
        try {
          ComboAddress ca(parts[0]+"."+parts[1]+"."+parts[2]+"."+parts[3]);
          return ca.toString();
        } catch (const PDNSException &e) {
          return allZerosIP;
        }
      } else if (parts.size() >= 1) {
        // either hex string, or 12-13-14-15
        vector<string> ip_parts;
        stringtok(ip_parts, parts[0], "-");
        unsigned int x1, x2, x3, x4;
        if (ip_parts.size() >= 4) {
          // 1-2-3-4 with any prefix (e.g. ip-foo-bar-1-2-3-4)
          string ret;
          for (size_t n=4; n > 0; n--) {
            auto octet = ip_parts[ip_parts.size() - n];
            try {
              auto octetVal = std::stol(octet);
              if (octetVal >= 0 && octetVal <= 255) {
                ret += ip_parts.at(ip_parts.size() - n) + ".";
              } else {
                return allZerosIP;
              }
            } catch (const std::exception &e) {
              return allZerosIP;
            }
          }
          ret.resize(ret.size() - 1); // remove trailing dot after last octet
          return ret;
        } else if(parts[0].length() == 10 && sscanf(parts[0].c_str()+2, "%02x%02x%02x%02x", &x1, &x2, &x3, &x4)==4) {
          return std::to_string(x1)+"."+std::to_string(x2)+"."+std::to_string(x3)+"."+std::to_string(x4);
        }
      }
      return allZerosIP;
    });

  lua.writeFunction("createForward6", []() {
      DNSName rel=s_lua_record_ctx->qname.makeRelative(s_lua_record_ctx->zone);
      auto parts = rel.getRawLabels();
      if(parts.size()==8) {
        string tot;
        for(int i=0; i<8; ++i) {
          if(i)
            tot.append(1,':');
          tot+=parts[i];
        }
        ComboAddress ca(tot);
        return ca.toString();
      }
      else if(parts.size()==1) {
        boost::replace_all(parts[0],"-",":");
        ComboAddress ca(parts[0]);
        return ca.toString();
      }

      return std::string("::");
    });
  lua.writeFunction("createReverse6", [](string format, boost::optional<std::unordered_map<string,string>> e){
      vector<ComboAddress> candidates;

      try {
        auto labels= s_lua_record_ctx->qname.getRawLabels();
        if(labels.size()<32)
          return std::string("unknown");
        boost::format fmt(format);
        fmt.exceptions( boost::io::all_error_bits ^ ( boost::io::too_many_args_bit | boost::io::too_few_args_bit )  );


        string together;
        vector<string> quads;
        for(int i=0; i<8; ++i) {
          if(i)
            together+=":";
          string lquad;
          for(int j=0; j <4; ++j) {
            lquad.append(1, labels[31-i*4-j][0]);
            together += labels[31-i*4-j][0];
          }
          quads.push_back(lquad);
        }
        ComboAddress ip6(together,0);

        if(e) {
          auto& addrs=*e;
          for(const auto& addr: addrs) {
            // this makes sure we catch all forms of the address
            if(ComboAddress(addr.first,0)==ip6)
              return addr.second;
          }
        }

        string dashed=ip6.toString();
        boost::replace_all(dashed, ":", "-");

        for(int i=31; i>=0; --i)
          fmt % labels[i];
        fmt % dashed;

        for(const auto& lquad : quads)
          fmt % lquad;

        return fmt.str();
      }
      catch(std::exception& ex) {
        g_log<<Logger::Error<<"LUA Record exception: "<<ex.what()<<endl;
      }
      catch(PDNSException& ex) {
        g_log<<Logger::Error<<"LUA Record exception: "<<ex.reason<<endl;
      }
      return std::string("unknown");
    });

  lua.writeFunction("filterForward", [](string address, NetmaskGroup& nmg, boost::optional<string> fallback) {
      ComboAddress ca(address);

      if (nmg.match(ComboAddress(address))) {
        return address;
      } else {
        if (fallback) {
          return *fallback;
        }

        if (ca.isIPv4()) {
          return string("0.0.0.0");
        } else {
          return string("::");
        }
      }
    });

  /*
   * Simplistic test to see if an IP address listens on a certain port
   * Will return a single IP address from the set of available IP addresses. If
   * no IP address is available, will return a random element of the set of
   * addresses supplied for testing.
   *
   * @example ifportup(443, { '1.2.3.4', '5.4.3.2' })"
   */
  lua.writeFunction("ifportup", [](int port, const vector<pair<int, string> >& ips, const boost::optional<std::unordered_map<string,string>> options) {
      vector<ComboAddress> candidates, unavailables;
      opts_t opts;
      vector<ComboAddress > conv;
      std::string selector;

      if(options)
        opts = *options;
      for(const auto& i : ips) {
        ComboAddress rem(i.second, port);
        if(g_up.isUp(rem, opts)) {
          candidates.push_back(rem);
        }
        else {
          unavailables.push_back(rem);
        }
      }
      if(!candidates.empty()) {
        // use regular selector
        selector = getOptionValue(options, "selector", "random");
      } else {
        // All units are down, apply backupSelector on all candidates
        candidates = std::move(unavailables);
        selector = getOptionValue(options, "backupSelector", "random");
      }

      vector<ComboAddress> res = useSelector(selector, s_lua_record_ctx->bestwho, candidates);
      return convIpListToString(res);
    });

  lua.writeFunction("ifurlup", [](const std::string& url,
                                          const boost::variant<iplist_t, ipunitlist_t>& ips,
                                          boost::optional<opts_t> options) {
      vector<vector<ComboAddress> > candidates;
      opts_t opts;
      if(options)
        opts = *options;
      if(auto simple = boost::get<iplist_t>(&ips)) {
        vector<ComboAddress> unit = convIplist(*simple);
        candidates.push_back(unit);
      } else {
        auto units = boost::get<ipunitlist_t>(ips);
        for(const auto& u : units) {
          vector<ComboAddress> unit = convIplist(u.second);
          candidates.push_back(unit);
        }
      }

      for(const auto& unit : candidates) {
        vector<ComboAddress> available;
        for(const auto& c : unit) {
          if(g_up.isUp(c, url, opts)) {
            available.push_back(c);
          }
        }
        if(!available.empty()) {
          vector<ComboAddress> res = useSelector(getOptionValue(options, "selector", "random"), s_lua_record_ctx->bestwho, available);
          return convIpListToString(res);
        }
      }

      // All units down, apply backupSelector on all candidates
      vector<ComboAddress> ret{};
      for(const auto& unit : candidates) {
        ret.insert(ret.end(), unit.begin(), unit.end());
      }

      vector<ComboAddress> res = useSelector(getOptionValue(options, "backupSelector", "random"), s_lua_record_ctx->bestwho, ret);
      return convIpListToString(res);
    });
  /*
   * Returns a random IP address from the supplied list
   * @example pickrandom({ '1.2.3.4', '5.4.3.2' })"
   */
  lua.writeFunction("pickrandom", [](const iplist_t& ips) {
      vector<ComboAddress> conv = convIplist(ips);

      return pickrandom(conv).toString();
    });


  /*
   * Returns a random IP address from the supplied list, as weighted by the
   * various ``weight`` parameters
   * @example pickwrandom({ {100, '1.2.3.4'}, {50, '5.4.3.2'}, {1, '192.168.1.0'} })
   */
  lua.writeFunction("pickwrandom", [](std::unordered_map<int, wiplist_t> ips) {
      vector<pair<int,ComboAddress> > conv = convWIplist(ips);

      return pickwrandom(conv).toString();
    });

  /*
   * Based on the hash of `bestwho`, returns an IP address from the list
   * supplied, as weighted by the various `weight` parameters
   * @example pickwhashed({ {15, '1.2.3.4'}, {50, '5.4.3.2'} })
   */
  lua.writeFunction("pickwhashed", [](std::unordered_map<int, wiplist_t > ips) {
      vector<pair<int,ComboAddress> > conv;

      conv.reserve(ips.size());
      for(auto& i : ips)
        conv.emplace_back(atoi(i.second[1].c_str()), ComboAddress(i.second[2]));

      return pickwhashed(s_lua_record_ctx->bestwho, conv).toString();
    });


  lua.writeFunction("pickclosest", [](const iplist_t& ips) {
      vector<ComboAddress > conv = convIplist(ips);

      return pickclosest(s_lua_record_ctx->bestwho, conv).toString();

    });

  if (g_luaRecordExecLimit > 0) {
      lua.executeCode(boost::str(boost::format("debug.sethook(report, '', %d)") % g_luaRecordExecLimit));
  }

  lua.writeFunction("report", [](string event, boost::optional<string> line){
      throw std::runtime_error("Script took too long");
    });

  lua.writeFunction("geoiplookup", [](const string &ip, const GeoIPInterface::GeoIPQueryAttribute attr) {
    return getGeo(ip, attr);
  });

  typedef const boost::variant<string,vector<pair<int,string> > > combovar_t;
  lua.writeFunction("continent", [](const combovar_t& continent) {
     string res=getGeo(s_lua_record_ctx->bestwho.toString(), GeoIPInterface::Continent);
      return doCompare(continent, res, [](const std::string& a, const std::string& b) {
          return !strcasecmp(a.c_str(), b.c_str());
        });
    });
  lua.writeFunction("asnum", [](const combovar_t& asns) {
      string res=getGeo(s_lua_record_ctx->bestwho.toString(), GeoIPInterface::ASn);
      return doCompare(asns, res, [](const std::string& a, const std::string& b) {
          return !strcasecmp(a.c_str(), b.c_str());
        });
    });
  lua.writeFunction("country", [](const combovar_t& var) {
      string res = getGeo(s_lua_record_ctx->bestwho.toString(), GeoIPInterface::Country2);
      return doCompare(var, res, [](const std::string& a, const std::string& b) {
          return !strcasecmp(a.c_str(), b.c_str());
        });

    });
  lua.writeFunction("netmask", [](const iplist_t& ips) {
      for(const auto& i :ips) {
        Netmask nm(i.second);
        if(nm.match(s_lua_record_ctx->bestwho))
          return true;
      }
      return false;
    });
  /* {
       {
        {'192.168.0.0/16', '10.0.0.0/8'},
        {'192.168.20.20', '192.168.20.21'}
       },
       {
        {'0.0.0.0/0'}, {'192.0.2.1'}
       }
     }
  */
  lua.writeFunction("view", [](const vector<pair<int, vector<pair<int, iplist_t> > > >& in) {
      for(const auto& rule : in) {
        const auto& netmasks=rule.second[0].second;
        const auto& destinations=rule.second[1].second;
        for(const auto& nmpair : netmasks) {
          Netmask nm(nmpair.second);
          if(nm.match(s_lua_record_ctx->bestwho)) {
            if (destinations.empty()) {
              throw std::invalid_argument("The IP list cannot be empty (for netmask " + nm.toString() + ")");
            }
            return destinations[dns_random(destinations.size())].second;
          }
        }
      }
      return std::string();
    }
    );


  lua.writeFunction("include", [&lua](string record) {
      DNSName rec;
      try {
        rec = DNSName(record) + s_lua_record_ctx->zone;
      } catch (const std::exception &e){
        g_log<<Logger::Error<<"Included record cannot be loaded, the name ("<<record<<") is malformed: "<<e.what()<<endl;
        return;
      }
      try {
        vector<DNSZoneRecord> drs = lookup(rec, QType::LUA, s_lua_record_ctx->zoneid);
        for(const auto& dr : drs) {
          auto lr = getRR<LUARecordContent>(dr.dr);
          lua.executeCode(lr->getCode());
        }
      }
      catch(std::exception& e) {
        g_log<<Logger::Error<<"Failed to load include record for LUArecord "<<rec<<": "<<e.what()<<endl;
      }
    });
}

std::vector<shared_ptr<DNSRecordContent>> luaSynth(const std::string& code, const DNSName& query, const DNSName& zone, int zoneid, const DNSPacket& dnsp, uint16_t qtype)
{
  if(!s_LUA ||                  // we don't have a Lua state yet
     !g_LuaRecordSharedState) { // or we want a new one even if we had one
    s_LUA = make_unique<AuthLua4>();
    setupLuaRecords();
  }

  std::vector<shared_ptr<DNSRecordContent>> ret;

  LuaContext& lua = *s_LUA->getLua();

  s_lua_record_ctx = std::unique_ptr<lua_record_ctx_t>(new lua_record_ctx_t());
  s_lua_record_ctx->qname = query;
  s_lua_record_ctx->zone = zone;
  s_lua_record_ctx->zoneid = zoneid;

  lua.writeVariable("qname", query);
  lua.writeVariable("zone", zone);
  lua.writeVariable("zoneid", zoneid);
  lua.writeVariable("who", dnsp.getRemote());
  lua.writeVariable("dh", (dnsheader*)&dnsp.d);
  lua.writeVariable("dnssecOK", dnsp.d_dnssecOk);
  lua.writeVariable("tcp", dnsp.d_tcp);
  lua.writeVariable("ednsPKTSize", dnsp.d_ednsRawPacketSizeLimit);
  if(dnsp.hasEDNSSubnet()) {
    lua.writeVariable("ecswho", dnsp.getRealRemote());
    s_lua_record_ctx->bestwho = dnsp.getRealRemote().getNetwork();
  }
  else {
    lua.writeVariable("ecswho", nullptr);
    s_lua_record_ctx->bestwho = dnsp.getRemote();
  }
  lua.writeVariable("bestwho", s_lua_record_ctx->bestwho);

  try {
    string actual;
    if(!code.empty() && code[0]!=';')
      actual = "return " + code;
    else
      actual = code.substr(1);

    auto content=lua.executeCode<boost::variant<string, vector<pair<int, string> > > >(actual);

    vector<string> contents;
    if(auto str = boost::get<string>(&content))
      contents.push_back(*str);
    else
      for(const auto& c : boost::get<vector<pair<int,string>>>(content))
        contents.push_back(c.second);

    for(const auto& content_it: contents) {
      if(qtype==QType::TXT)
        ret.push_back(DNSRecordContent::mastermake(qtype, QClass::IN, '"'+content_it+'"' ));
      else
        ret.push_back(DNSRecordContent::mastermake(qtype, QClass::IN, content_it ));
    }
  } catch(std::exception &e) {
    g_log << Logger::Info << "Lua record ("<<query<<"|"<<QType(qtype).toString()<<") reported: " << e.what();
    try {
      std::rethrow_if_nested(e);
      g_log<<endl;
    } catch(const std::exception& ne) {
      g_log << ": " << ne.what() << std::endl;
    }
    catch(const PDNSException& ne) {
      g_log << ": " << ne.reason << std::endl;
    }
    throw ;
  }

  return ret;
}