1 files changed, 120 insertions, 0 deletions
diff --git a/remote_logger.hh b/remote_logger.hh
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+/*
+ * This file is part of PowerDNS or dnsdist.
+ * Copyright -- PowerDNS.COM B.V. and its contributors
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * In addition, for the avoidance of any doubt, permission is granted to
+ * link this program with OpenSSL and to (re)distribute the binaries
+ * produced as the result of such linking.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+#pragma once
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <atomic>
+#include <queue>
+#include <thread>
+
+#include "iputils.hh"
+#include "circular_buffer.hh"
+#include "lock.hh"
+#include "sstuff.hh"
+
+/* Writes can be submitted and they are atomically accepted. Either the whole write
+   ends up in the buffer or nothing ends up in the buffer.
+   In case nothing ends up in the buffer, an exception is thrown.
+   Similarly, EOF leads to this treatment
+
+   The filedescriptor can be in non-blocking mode.
+
+   This class is not threadsafe.
+*/
+
+class CircularWriteBuffer
+{
+public:
+  explicit CircularWriteBuffer(size_t size) : d_buffer(size)
+  {
+  }
+
+  bool hasRoomFor(const std::string& str) const;
+  bool write(const std::string& str);
+  bool flush(int fd);
+private:
+  boost::circular_buffer<char> d_buffer;
+};
+
+class RemoteLoggerInterface
+{
+public:
+  virtual ~RemoteLoggerInterface() {};
+  virtual void queueData(const std::string& data) = 0;
+  virtual std::string toString() const = 0;
+
+  bool logQueries(void) const { return d_logQueries; }
+  bool logResponses(void) const { return d_logResponses; }
+  void setLogQueries(bool flag) { d_logQueries = flag; }
+  void setLogResponses(bool flag) { d_logResponses = flag; }
+
+private:
+  bool d_logQueries{true};
+  bool d_logResponses{true};
+};
+
+/* Thread safe. Will connect asynchronously on request.
+   Runs a reconnection thread that also periodicall flushes.
+   Note that the buffer only runs as long as there is a connection.
+   If there is no connection we don't buffer a thing
+*/
+class RemoteLogger : public RemoteLoggerInterface
+{
+public:
+  RemoteLogger(const ComboAddress& remote, uint16_t timeout=2,
+               uint64_t maxQueuedBytes=100000,
+               uint8_t reconnectWaitTime=1,
+               bool asyncConnect=false);
+  ~RemoteLogger();
+  void queueData(const std::string& data) override;
+  std::string toString() const override
+  {
+    return d_remote.toStringWithPort() + " (" + std::to_string(d_processed) + " processed, " + std::to_string(d_drops) + " dropped)";
+  }
+  void stop()
+  {
+    d_exiting = true;
+  }
+
+private:
+  bool reconnect();
+  void maintenanceThread();
+
+  struct RuntimeData
+  {
+    CircularWriteBuffer d_writer;
+    std::unique_ptr<Socket> d_socket{nullptr};
+  };
+
+  ComboAddress d_remote;
+  std::atomic<uint64_t> d_drops{0};
+  std::atomic<uint64_t> d_processed{0};
+  uint16_t d_timeout;
+  uint8_t d_reconnectWaitTime;
+  std::atomic<bool> d_exiting{false};
+  bool d_asyncConnect{false};
+
+  LockGuarded<RuntimeData> d_runtime;
+  std::thread d_thread;
+};