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