pdns/dnsproxy.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 PDNS_DNSPROXY
  23 #define PDNS_DNSPROXY
  24 #include <pthread.h>
  25 #include <map>
  26 #include <sys/socket.h>
  27 #include <netinet/in.h>
  28 #include <arpa/inet.h>
  29 #include "dnspacket.hh"
  30 #include "lock.hh"
  31 #include "iputils.hh"
  32
  33 #include "namespaces.hh"
  34
  35 /**
  36
  37 how will this work.
  38
  39 This is a thread that just throws packets around. Should handle ~1000 packets/second.
  40
  41 Consists of a thread receiving packets back from the backend and retransmitting them to the original client.
  42
  43 Furthermore, it provides a member function that reports the packet to the connection tracker and actually sends it out.
  44
  45 The sending happens from a source port that is determined by the constructor, but IS random. Furthermore, the ID is XOR-ed with a random value
  46 to make sure outside parties can't spoof us.
  47
  48 To fix: how to remove the stale entries that will surely accumulate
  49 */
  50
  51 class DNSProxy
  52 {
  53 public:
  54   DNSProxy(const string &ip); //!< creates socket
  55   ~DNSProxy(); //<! dtor for DNSProxy
  56   void go(); //!< launches the actual thread
  57   bool completePacket(DNSPacket *r, const DNSName& target,const DNSName& aname, const uint8_t scopeMask);
  58
  59   void mainloop();                  //!< this is the main loop that receives reply packets and sends them out again
  60   static void *launchhelper(void *p)
  61   {
  62     static_cast<DNSProxy *>(p)->mainloop();
  63     return 0;
  64   }
  65   bool recurseFor(DNSPacket* p);
  66 private:
  67   struct ConntrackEntry
  68   {
  69     time_t created;
  70     boost::optional<ComboAddress> anyLocal;
  71     DNSName qname;
  72     DNSPacket* complete;
  73     DNSName aname;
  74     uint8_t anameScopeMask;
  75     ComboAddress remote;
  76     uint16_t id;
  77     uint16_t qtype;
  78     int outsock;
  79   };
  80
  81   typedef map<int,ConntrackEntry> map_t;
  82
  83   // Data
  84   ComboAddress d_remote;
  85   AtomicCounter* d_resanswers;
  86   AtomicCounter* d_udpanswers;
  87   AtomicCounter* d_resquestions;
  88   pthread_mutex_t d_lock;
  89   map_t d_conntrack;
  90   int d_sock;
  91   int getID_locked();
  92   uint16_t d_xor;
  93 };
  94
  95 #endif