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 #ifndef NAMESERVER_HH
  23 #define NAMESERVER_HH
  24
  25 #include <poll.h>
  26 #include <sys/types.h>
  27 #include <sys/socket.h>
  28 #include <netinet/in.h>
  29 #include <sys/time.h>
  30 #include <unistd.h>
  31 #include <arpa/inet.h>
  32 #include <netdb.h>
  33 #include <vector>
  34
  35 #include "statbag.hh"
  36 #include "namespaces.hh"
  37 #include "dnspacket.hh"
  38 #include "responsestats.hh"
  39
  40 /** This is the main class. It opens a socket on udp port 53 and waits for packets. Those packets can
  41     be retrieved with the receive() member function, which returns a DNSPacket.
  42
  43     Some sample code in main():
  44     \code
  45     typedef Distributor<DNSPacket,DNSPacket,PacketHandler> DNSDistributor;
  46     DNSDistributor D(6); // the big dispatcher!
  47
  48     pthread_t qtid, atid;
  49     N=new UDPNameserver;
  50
  51     pthread_create(&qtid,0,qthread,static_cast<void *>(&D)); // receives packets
  52     pthread_create(&atid,0,athread,static_cast<void *>(&D)); // sends packets
  53     \endcode
  54
  55     Code for qthread:
  56     \code
  57     void *qthread(void *p)
  58     {
  59       DNSDistributor *D=static_cast<DNSDistributor *>(p);
  60
  61       DNSPacket *P;
  62
  63       while((P=N->receive())) // receive a packet
  64       {
  65          D->question(P); // and give to the distributor, they will delete it
  66       }
  67       return 0;
  68     }
  69
  70     \endcode
  71
  72 */
  73
  74 #ifdef __linux__
  75 #ifndef SO_REUSEPORT
  76 #define SO_REUSEPORT 15
  77 #endif
  78 #endif
  79
  80 class UDPNameserver
  81 {
  82 public:
  83   UDPNameserver( bool additional_socket = false );  //!< Opens the socket
  84   DNSPacket *receive(DNSPacket *prefilled, std::string& buffer); //!< call this in a while or for(;;) loop to get packets
  85   void send(DNSPacket *); //!< send a DNSPacket. Will call DNSPacket::truncate() if over 512 bytes
  86   inline bool canReusePort() {
  87 #ifdef SO_REUSEPORT
  88     return d_can_reuseport;
  89 #else
  90     return false;
  91 #endif
  92   };
  93
  94 private:
  95   bool d_additional_socket;
  96 #ifdef SO_REUSEPORT
  97   bool d_can_reuseport;
  98 #endif
  99   vector<int> d_sockets;
 100   void bindIPv4();
 101   void bindIPv6();
 102   vector<pollfd> d_rfds;
 103 };
 104
 105 bool AddressIsUs(const ComboAddress& remote);
 106
 107 extern ResponseStats g_rs;
 108
 109 #endif