Added class LogPeriod, a class intended to help with server-side

logging by forming log filenames with a timestamp and facilitating
log rollover.

openvpn/log/logperiod.hpp

@@ -0,0 +1,159 @@
+//    OpenVPN -- An application to securely tunnel IP networks
+//               over a single port, with support for SSL/TLS-based
+//               session authentication and key exchange,
+//               packet encryption, packet authentication, and
+//               packet compression.
+//
+//    Copyright (C) 2012-2015 OpenVPN Technologies, Inc.
+//
+//    This program is free software: you can redistribute it and/or modify
+//    it under the terms of the GNU Affero General Public License Version 3
+//    as published by the Free Software Foundation.
+//
+//    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 Affero General Public License for more details.
+//
+//    You should have received a copy of the GNU Affero General Public License
+//    along with this program in the COPYING file.
+//    If not, see <http://www.gnu.org/licenses/>.
+
+#ifndef OPENVPN_LOG_LOGPERIOD_H
+#define OPENVPN_LOG_LOGPERIOD_H
+
+#include <sys/time.h> // for time_t
+
+#include <string>
+#include <sstream>
+#include <iomanip> // for setfill and setw
+
+#include <openvpn/common/olong.hpp>
+#include <openvpn/common/exception.hpp>
+#include <openvpn/time/time.hpp>
+#include <openvpn/time/timestr.hpp>
+
+namespace openvpn {
+  class LogPeriod
+  {
+  public:
+    OPENVPN_EXCEPTION(log_period_error);
+
+    enum Period {
+      UNDEF,
+      DAILY,
+      HOURLY,
+      BY_MINUTE,
+    };
+
+    LogPeriod()
+      : start_(0),
+	end_(0),
+	period_(UNDEF)
+    {
+    }
+
+    LogPeriod(const Period period, const time_t base)
+    {
+      period_ = period;
+      const olong p = period_sec(period_);
+      start_ = period_base(period_, base);
+      end_ = start_ + p;
+    }
+
+    LogPeriod(const LogPeriod& other, const int index)
+    {
+      period_ = other.period_;
+      const olong p = period_sec(period_);
+      start_ = other.start_ + p * olong(index);
+      end_ = start_ + p;
+    }
+
+    bool is_current(const time_t now) const
+    {
+      return olong(now) >= start_ && olong(now) < end_;
+    }
+
+    std::string to_string_verbose() const
+    {
+      return date_time(start_) + " -> " + date_time(end_);
+    }
+
+    std::string to_string() const
+    {
+      std::ostringstream os;
+      struct tm lt;
+      const time_t time = time_t(start_);
+      if (!localtime_r(&time, &lt))
+	throw log_period_error("to_string localtime_r");
+      os << std::setfill('0');
+      os << std::setw(4) << (lt.tm_year + 1900) << '.' << std::setw(2) << (lt.tm_mon + 1) << '.' << std::setw(2) << lt.tm_mday;
+      if (period_ == HOURLY || period_ == BY_MINUTE)
+	os << '-' << std::setw(2) << lt.tm_hour << ':' << std::setw(2) << lt.tm_min;
+      return os.str();
+    }
+
+    static Period period_from_string(const std::string& str)
+    {
+      if (str == "daily")
+	return DAILY;
+      else if (str == "hourly")
+	return HOURLY;
+      else if (str == "by_minute")
+	return BY_MINUTE;
+      else
+	throw log_period_error("unknown period: " + str);
+    }
+
+  private:
+    static olong period_sec(const Period p)
+    {
+      switch (p)
+	{
+	case DAILY:
+	  return 86400;
+	case HOURLY:
+	  return 3600;
+	case BY_MINUTE:
+	  return 60;
+	default:
+	  throw log_period_error("undefined period");
+	}
+    }
+
+    static olong period_base(const Period p, const time_t time)
+    {
+      struct tm lt;
+      if (!localtime_r(&time, &lt))
+	throw log_period_error("period_base localtime_r");
+      switch (p)
+	{
+	case DAILY:
+	  lt.tm_hour = 0;
+	  lt.tm_min = 0;
+	  lt.tm_sec = 0;
+	  break;
+	case HOURLY:
+	  lt.tm_min = 0;
+	  lt.tm_sec = 0;
+	  break;
+	case BY_MINUTE:
+	  lt.tm_sec = 0;
+	  break;
+	default:
+	  throw log_period_error("unknown period");
+	}
+      const time_t ret = mktime(&lt);
+      if (ret == -1)
+	throw log_period_error("mktime");
+      return olong(ret);
+    }
+
+  private:
+    olong start_;
+    olong end_;
+    Period period_;
+  };
+}
+
+#endif