pdns/remote_logger.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 #ifdef HAVE_CONFIG_H
  24 #include "config.h"
  25 #endif
  26
  27 #include <atomic>
  28 #include <condition_variable>
  29 #include <queue>
  30 #include <thread>
  31
  32 #include "iputils.hh"
  33 #include "circular_buffer.hh"
  34
  35 /* Writes can be submitted and they are atomically accepted. Either the whole write
  36    ends up in the buffer or nothing ends up in the buffer.
  37    In case nothing ends up in the buffer, an exception is thrown.
  38    Similarly, EOF leads to this treatment
  39
  40    The filedescriptor can be in non-blocking mode.
  41
  42    This class is not threadsafe.
  43 */
  44
  45 class CircularWriteBuffer
  46 {
  47 public:
  48   explicit CircularWriteBuffer(int fd, size_t size) : d_fd(fd), d_buffer(size)
  49   {
  50   }
  51
  52   void write(const std::string& str);
  53   void flush();
  54 private:
  55   int d_fd;
  56   boost::circular_buffer<char> d_buffer;
  57 };
  58
  59 class RemoteLoggerInterface
  60 {
  61 public:
  62   virtual ~RemoteLoggerInterface() {};
  63   virtual void queueData(const std::string& data) = 0;
  64   virtual std::string toString() const = 0;
  65
  66   bool logQueries(void) const { return d_logQueries; }
  67   bool logResponses(void) const { return d_logResponses; }
  68   void setLogQueries(bool flag) { d_logQueries = flag; }
  69   void setLogResponses(bool flag) { d_logResponses = flag; }
  70
  71 private:
  72   bool d_logQueries{true};
  73   bool d_logResponses{true};
  74 };
  75
  76 /* Thread safe. Will connect asynchronously on request.
  77    Runs a reconnection thread that also periodicall flushes.
  78    Note that the buffer only runs as long as there is a connection.
  79    If there is no connection we don't buffer a thing
  80 */
  81 class RemoteLogger : public RemoteLoggerInterface
  82 {
  83 public:
  84   RemoteLogger(const ComboAddress& remote, uint16_t timeout=2,
  85                uint64_t maxQueuedBytes=100000,
  86                uint8_t reconnectWaitTime=1,
  87                bool asyncConnect=false);
  88   ~RemoteLogger();
  89   void queueData(const std::string& data) override;
  90   std::string toString() const override
  91   {
  92     return d_remote.toStringWithPort();
  93   }
  94   void stop()
  95   {
  96     d_exiting = true;
  97   }
  98   std::atomic<uint32_t> d_drops{0};
  99
 100 private:
 101   bool reconnect();
 102   void maintenanceThread();
 103
 104   ComboAddress d_remote;
 105   uint64_t d_maxQueuedBytes;
 106   int d_socket{-1};
 107   std::unique_ptr<CircularWriteBuffer> d_writer;
 108   uint16_t d_timeout;
 109   uint8_t d_reconnectWaitTime;
 110   std::atomic<bool> d_exiting{false};
 111   bool d_asyncConnect{false};
 112
 113   std::mutex d_mutex;
 114   std::thread d_thread;
 115 };