pdns/logging.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
  23 #pragma once
  24
  25 #include "config.h"
  26
  27 #ifdef RECURSOR
  28
  29 #include <map>
  30 #include <memory>
  31 #include <string>
  32 #include <sstream>
  33 #include <boost/optional.hpp>
  34
  35 #include "logr.hh"
  36 #include "dnsname.hh"
  37 #include "iputils.hh"
  38
  39 namespace Logging
  40 {
  41
  42 struct Entry
  43 {
  44   boost::optional<std::string> name; // name parts joined with '.'
  45   std::string message; // message as send to log call
  46   boost::optional<std::string> error; // error if .Error() was called
  47   struct timeval d_timestamp; // time of entry generation
  48   std::map<std::string, std::string> values; // key-value pairs
  49   size_t level; // level at which this was logged
  50   Logr::Priority d_priority; // (syslog) priority)
  51 };
  52
  53 // Warning: some meta-programming is going on.  We define helper
  54 // templates that can be used to see if specific string output
  55 // functions are available.  If so, we use those instead of << into an
  56 // ostringstream. Note that this decision happpens compile time.
  57 // Some hints taken from https://www.cppstories.com/2019/07/detect-overload-from-chars/
  58 // (I could not get function templates with enabled_if<> to work in this case)
  59 //
  60 // Default: std::string(T) is not available
  61 template <typename T, typename = void>
  62 struct is_to_string_available : std::false_type
  63 {
  64 };
  65
  66 // If std::string(T) is available this template is used
  67 template <typename T>
  68 struct is_to_string_available<T, std::void_t<decltype(std::to_string(std::declval<T>()))>> : std::true_type
  69 {
  70 };
  71
  72 // Same mechanism for t.toLogString() and t.toStructuredLogString()
  73 template <typename T, typename = void>
  74 struct is_toLogString_available : std::false_type
  75 {
  76 };
  77
  78 template <typename T>
  79 struct is_toLogString_available<T, std::void_t<decltype(std::declval<T>().toLogString())>> : std::true_type
  80 {
  81 };
  82
  83 template <typename T, typename = void>
  84 struct is_toStructuredLogString_available : std::false_type
  85 {
  86 };
  87
  88 template <typename T>
  89 struct is_toStructuredLogString_available<T, std::void_t<decltype(std::declval<T>().toStructuredLogString())>> : std::true_type
  90 {
  91 };
  92
  93 template <typename T, typename = void>
  94 struct is_toString_available : std::false_type
  95 {
  96 };
  97
  98 template <typename T>
  99 struct is_toString_available<T, std::void_t<decltype(std::declval<T>().toString())>> : std::true_type
 100 {
 101 };
 102
 103 const char* toTimestampStringMilli(const struct timeval& tval, std::array<char, 64>& buf, const std::string& format = "%s");
 104
 105 template <typename T>
 106 struct Loggable : public Logr::Loggable
 107 {
 108   const T& _t;
 109   Loggable(const T& v) :
 110     _t(v)
 111   {
 112   }
 113   std::string to_string() const
 114   {
 115     if constexpr (std::is_same_v<T, std::string>) {
 116       return _t;
 117     }
 118     else if constexpr (is_toStructuredLogString_available<T>::value) {
 119       return _t.toStructuredLogString();
 120     }
 121     else if constexpr (is_toLogString_available<T>::value) {
 122       return _t.toLogString();
 123     }
 124     else if constexpr (is_toString_available<T>::value) {
 125       return _t.toString();
 126     }
 127     else if constexpr (is_to_string_available<T>::value) {
 128       return std::to_string(_t);
 129     }
 130     else {
 131       std::ostringstream oss;
 132       oss << _t;
 133       return oss.str();
 134     }
 135   }
 136 };
 137
 138 template <typename T>
 139 struct IterLoggable : public Logr::Loggable
 140 {
 141   const T& _t1;
 142   const T& _t2;
 143   IterLoggable(const T& v1, const T& v2) :
 144     _t1(v1), _t2(v2)
 145   {
 146   }
 147   std::string to_string() const
 148   {
 149     std::ostringstream oss;
 150     bool first = true;
 151     for (auto i = _t1; i != _t2; i++) {
 152       if (!first) {
 153         oss << ' ';
 154       }
 155       else {
 156         first = false;
 157       }
 158       oss << *i;
 159     }
 160     return oss.str();
 161   }
 162 };
 163
 164 typedef void (*EntryLogger)(const Entry&);
 165
 166 class Logger : public Logr::Logger, public std::enable_shared_from_this<const Logger>
 167 {
 168 public:
 169   bool enabled(Logr::Priority) const override;
 170
 171   void info(const std::string& msg) const override;
 172   void info(Logr::Priority, const std::string& msg) const override;
 173   void error(int err, const std::string& msg) const override;
 174   void error(const std::string& err, const std::string& msg) const override;
 175   void error(Logr::Priority, int err, const std::string& msg) const override;
 176   void error(Logr::Priority, const std::string& err, const std::string& msg) const override;
 177
 178   std::shared_ptr<Logr::Logger> v(size_t level) const override;
 179   std::shared_ptr<Logr::Logger> withValues(const std::map<std::string, std::string>& values) const override;
 180   virtual std::shared_ptr<Logr::Logger> withName(const std::string& name) const override;
 181
 182   static std::shared_ptr<Logger> create(EntryLogger callback);
 183   static std::shared_ptr<Logger> create(EntryLogger callback, const std::string& name);
 184
 185   Logger(EntryLogger callback);
 186   Logger(EntryLogger callback, boost::optional<std::string> name);
 187   Logger(std::shared_ptr<const Logger> parent, boost::optional<std::string> name, size_t verbosity, size_t lvl, EntryLogger callback);
 188   virtual ~Logger();
 189
 190   size_t getVerbosity() const;
 191   void setVerbosity(size_t verbosity);
 192
 193 private:
 194   void logMessage(const std::string& msg, boost::optional<const std::string> err) const;
 195   void logMessage(const std::string& msg, Logr::Priority p, boost::optional<const std::string> err) const;
 196   std::shared_ptr<const Logger> getptr() const;
 197
 198   std::shared_ptr<const Logger> _parent{nullptr};
 199   EntryLogger _callback;
 200   boost::optional<std::string> _name;
 201   std::map<std::string, std::string> _values;
 202   // current Logger's level. the higher the more verbose.
 203   size_t _level{0};
 204   // verbosity settings. messages with level higher's than verbosity won't appear
 205   size_t _verbosity{0};
 206 };
 207 }
 208
 209 extern std::shared_ptr<Logging::Logger> g_slog;
 210
 211 // Prefer structured logging? Since Recursor 5.1.0, we always do. We keep a const, to allow for
 212 // step-by-step removal of old style logging code (for recursor-only code). Note that code shared
 213 // with auth still uses old-style, so the SLOG calls should remain for shared code.
 214 constexpr bool g_slogStructured = true;
 215
 216 // A helper macro to switch between old-style logging and new-style (structured logging)
 217 // A typical use:
 218 //
 219 // SLOG(g_log<<Logger::Warning<<"Unable to parse configuration file '"<<configname<<"'"<<endl,
 220 //      startupLog->error("No such file", "Unable to parse configuration file", "config_file", Logging::Loggable(configname));
 221 //
 222 // NOLINTNEXTLINE(cppcoreguidelines-macro-usage)
 223 #define SLOG(oldStyle, slogCall) \
 224   do {                           \
 225     slogCall;                    \
 226   } while (0)
 227
 228 #else // No structured logging (e.g. auth)
 229 // NOLINTNEXTLINE(cppcoreguidelines-macro-usage)
 230 #define SLOG(oldStyle, slogCall) \
 231   do {                           \
 232     oldStyle;                    \
 233   } while (0)
 234 #endif // RECURSOR