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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
#include "config.h"
#ifdef RECURSOR
#include <map>
#include <memory>
#include <string>
#include <sstream>
#include <boost/optional.hpp>
#include "logr.hh"
#include "dnsname.hh"
#include "iputils.hh"
namespace Logging
{
struct Entry
{
boost::optional<std::string> name; // name parts joined with '.'
std::string message; // message as send to log call
boost::optional<std::string> error; // error if .Error() was called
struct timeval d_timestamp; // time of entry generation
std::map<std::string, std::string> values; // key-value pairs
size_t level; // level at which this was logged
Logr::Priority d_priority; // (syslog) priority)
};
// Warning: some meta-programming is going on. We define helper
// templates that can be used to see if specific string output
// functions are available. If so, we use those instead of << into an
// ostringstream. Note that this decision happpens compile time.
// Some hints taken from https://www.cppstories.com/2019/07/detect-overload-from-chars/
// (I could not get function templates with enabled_if<> to work in this case)
//
// Default: std::string(T) is not available
template <typename T, typename = void>
struct is_to_string_available : std::false_type
{
};
// If std::string(T) is available this template is used
template <typename T>
struct is_to_string_available<T, std::void_t<decltype(std::to_string(std::declval<T>()))>> : std::true_type
{
};
// Same mechanism for t.toLogString()
template <typename T, typename = void>
struct is_toLogString_available : std::false_type
{
};
template <typename T>
struct is_toLogString_available<T, std::void_t<decltype(std::declval<T>().toLogString())>> : std::true_type
{
};
template <typename T, typename = void>
struct is_toString_available : std::false_type
{
};
template <typename T>
struct is_toString_available<T, std::void_t<decltype(std::declval<T>().toString())>> : std::true_type
{
};
template <typename T>
struct Loggable : public Logr::Loggable
{
const T& _t;
Loggable(const T& v) :
_t(v)
{
}
std::string to_string() const
{
if constexpr (std::is_same_v<T, std::string>) {
return _t;
}
else if constexpr (is_toLogString_available<T>::value) {
return _t.toLogString();
}
else if constexpr (is_toString_available<T>::value) {
return _t.toString();
}
else if constexpr (is_to_string_available<T>::value) {
return std::to_string(_t);
}
else {
std::ostringstream oss;
oss << _t;
return oss.str();
}
}
};
template <typename T>
struct IterLoggable : public Logr::Loggable
{
const T& _t1;
const T& _t2;
IterLoggable(const T& v1, const T& v2) :
_t1(v1), _t2(v2)
{
}
std::string to_string() const
{
std::ostringstream oss;
bool first = true;
for (auto i = _t1; i != _t2; i++) {
if (!first) {
oss << ' ';
}
else {
first = false;
}
oss << *i;
}
return oss.str();
}
};
typedef void (*EntryLogger)(const Entry&);
class Logger : public Logr::Logger, public std::enable_shared_from_this<const Logger>
{
public:
bool enabled(Logr::Priority) const override;
void info(const std::string& msg) const override;
void info(Logr::Priority, const std::string& msg) const override;
void error(int err, const std::string& msg) const override;
void error(const std::string& err, const std::string& msg) const override;
void error(Logr::Priority, int err, const std::string& msg) const override;
void error(Logr::Priority, const std::string& err, const std::string& msg) const override;
std::shared_ptr<Logr::Logger> v(size_t level) const override;
std::shared_ptr<Logr::Logger> withValues(const std::map<std::string, std::string>& values) const override;
virtual std::shared_ptr<Logr::Logger> withName(const std::string& name) const override;
static std::shared_ptr<Logger> create(EntryLogger callback);
static std::shared_ptr<Logger> create(EntryLogger callback, const std::string& name);
Logger(EntryLogger callback);
Logger(EntryLogger callback, boost::optional<std::string> name);
Logger(std::shared_ptr<const Logger> parent, boost::optional<std::string> name, size_t verbosity, size_t lvl, EntryLogger callback);
virtual ~Logger();
size_t getVerbosity() const;
void setVerbosity(size_t verbosity);
private:
void logMessage(const std::string& msg, boost::optional<const std::string> err) const;
void logMessage(const std::string& msg, Logr::Priority p, boost::optional<const std::string> err) const;
std::shared_ptr<const Logger> getptr() const;
std::shared_ptr<const Logger> _parent{nullptr};
EntryLogger _callback;
boost::optional<std::string> _name;
std::map<std::string, std::string> _values;
// current Logger's level. the higher the more verbose.
size_t _level{0};
// verbosity settings. messages with level higher's than verbosity won't appear
size_t _verbosity{0};
};
}
extern std::shared_ptr<Logging::Logger> g_slog;
// Prefer structured logging?
extern bool g_slogStructured;
// A helper macro to switch between old-style logging and new-style (structured logging)
// A typical use:
//
// SLOG(g_log<<Logger::Warning<<"Unable to parse configuration file '"<<configname<<"'"<<endl,
// startupLog->error("No such file", "Unable to parse configuration file", "config_file", Logging::Loggable(configname));
//
#define SLOG(oldStyle, slogCall) \
do { \
if (g_slogStructured) { \
slogCall; \
} \
else { \
oldStyle; \
} \
} while (0);
#else // No structured logging (e.g. auth)
#define SLOG(oldStyle, slogCall) \
do { \
oldStyle; \
} while (0);
#endif // RECURSOR
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