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