pdns/nameserver.hh

   1 /*
   2  * This file is part of PowerDNS or dnsdist.
   3  * Copyright -- PowerDNS.COM B.V. and its contributors
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of version 2 of the GNU General Public License as
   7  * published by the Free Software Foundation.
   8  *
   9  * In addition, for the avoidance of any doubt, permission is granted to
  10  * link this program with OpenSSL and to (re)distribute the binaries
  11  * produced as the result of such linking.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  21  */
  22 #pragma once
  23 #include <poll.h>
  24 #include <sys/types.h>
  25 #include <sys/socket.h>
  26 #include <netinet/in.h>
  27 #include <sys/time.h>
  28 #include <unistd.h>
  29 #include <arpa/inet.h>
  30 #include <netdb.h>
  31 #include <vector>
  32
  33 #include "statbag.hh"
  34 #include "namespaces.hh"
  35 #include "dnspacket.hh"
  36 #include "responsestats.hh"
  37
  38 /** This is the main class. It opens a socket on udp port 53 and waits for packets. Those packets can
  39     be retrieved with the receive() member function, which returns a DNSPacket.
  40
  41     Some sample code in main():
  42     \code
  43     typedef Distributor<DNSPacket,DNSPacket,PacketHandler> DNSDistributor;
  44     DNSDistributor D(6); // the big dispatcher!
  45
  46     pthread_t qtid, atid;
  47     N=new UDPNameserver;
  48
  49     pthread_create(&qtid,0,qthread,static_cast<void *>(&D)); // receives packets
  50     pthread_create(&atid,0,athread,static_cast<void *>(&D)); // sends packets
  51     \endcode
  52
  53     Code for qthread:
  54     \code
  55     void *qthread(void *p)
  56     {
  57       DNSDistributor *D=static_cast<DNSDistributor *>(p);
  58
  59       DNSPacket *P;
  60
  61       while((P=N->receive())) // receive a packet
  62       {
  63          D->question(P); // and give to the distributor, they will delete it
  64       }
  65       return 0;
  66     }
  67
  68     \endcode
  69
  70 */
  71
  72 #ifdef __linux__
  73 #ifndef SO_REUSEPORT
  74 #define SO_REUSEPORT 15
  75 #endif
  76 #endif
  77
  78 class UDPNameserver
  79 {
  80 public:
  81   UDPNameserver( bool additional_socket = false );  //!< Opens the socket
  82   bool receive(DNSPacket& packet, std::string& buffer); //!< call this in a while or for(;;) loop to get packets
  83   void send(DNSPacket&); //!< send a DNSPacket. Will call DNSPacket::truncate() if over 512 bytes
  84   inline bool canReusePort() {
  85     return d_can_reuseport;
  86   };
  87
  88 private:
  89   bool d_additional_socket;
  90   bool d_can_reuseport{false};
  91   vector<int> d_sockets;
  92   void bindAddresses();
  93   vector<pollfd> d_rfds;
  94 };
  95
  96 bool AddressIsUs(const ComboAddress& remote);
  97
  98 extern ResponseStats g_rs;