// OpenVPN 3 Linux client -- Next generation OpenVPN client // // SPDX-License-Identifier: AGPL-3.0-only // // Copyright (C) 2018 - 2023 OpenVPN Inc // Copyright (C) 2018 - 2023 David Sommerseth // /** * @file logwriter.hpp * * @brief Base class declaration for a generic logging interface (API) * */ #pragma once #include #include #include #include #include "build-config.h" #include "events/log.hpp" #include "events/status.hpp" #include "logtag.hpp" #include "logmetadata.hpp" /** * Base class providing a generic API for writing log data * to an output stream */ class LogWriter { public: using Ptr = std::shared_ptr; LogWriter() = default; virtual ~LogWriter() = default; /** * Retrieve information about the configured LogWriter backend in use * * @return Returns a std::string with information about the backend */ virtual const std::string GetLogWriterInfo() const = 0; /** * Turns on/off prefixing log lines with the timestamp of the log event * * @param tstamp Boolean flag to enable (true) or disable (false) * timestamps */ virtual void EnableTimestamp(const bool tstamp) final { timestamp = tstamp; } virtual bool TimestampEnabled() { return timestamp; } /** * Turns on/off logging meta data * * @param meta Boolean to enable (true) or disable (false) the * the meta data logging */ void EnableLogMeta(const bool meta) { log_meta = meta; } bool LogMetaEnabled() { return log_meta; } /** * Turns on/off prepending log events with LogTag information before * log message * * @param mp Boolean flag to enable (true) or disable (false) * the log tag prepending */ void EnableMessagePrepend(const bool mp) { prepend_prefix = mp; } bool MessagePrependEnabled() const noexcept { return prepend_prefix; } /** * Writes log data to the destination buffer * * This will call the WriteLogTag() with the logtag argument being * nullptr * * @param data std::string of data to be written * @param colour_init std::string to be printed before log data, to * set the proper colours. Empty by default. * @param colour_reset std::string to be printed after the log data * to reset colour selection. Empty by default. */ void Write(const std::string &data, const std::string &colour_init = "", const std::string &colour_reset = "") { WriteLogLine(nullptr, data, colour_init, colour_reset); } /** * Writes log data to the destination buffer, but will prefix * log lines with information about the log group and log category * * This will call the WriteLogTag() with the logtag argument being * nullptr * * @param grp LogGroup the log message belongs to * @param ctg LogCategory the log message is categorized as * @param data std::string containing the log data * @param colour_init (optional) std::string to be printed before log * data, to set the proper colours. Emtpy by default. * @param colour_reset (optional) std::string to be printed after the log * data to reset colour selection. Emtpy by default. */ void Write(const LogGroup grp, const LogCategory ctg, const std::string &data, const std::string &colour_init = "", const std::string &colour_reset = "") { WriteLogLine(nullptr, LogPrefix(grp, ctg) + data, colour_init, colour_reset); } /** * Writes a LogEvent() object in a formatted way. * * If the Events::Log object contains a LogTag, this will * be provided to the logging backend * * @param logev Populated LogEvent() object to log * */ virtual void Write(const Events::Log &logev) { WriteLogLine(logev.GetLogTag(), logev.group, logev.category, logev.message); } /** * Writes an Events::Status object to the log stream * * These events will be prefixed with '[STATUS]' unless the * prefix argument is provided. * @param status Events::Status object to log * @param prefix Override the prefix appearing in front * of the logged status event */ virtual void WriteStatus(const Events::Status &status, const std::string &prefix = "[STATUS]") { std::ostringstream msg; Events::Status ev(status); ev.SetPrintMode(Events::Status::PrintMode::ALL); msg << prefix << (!prefix.empty() ? " " : "") << ev; Write(msg.str()); } /** * Adds meta log info, which is printed before the log line * written by Write(). This must be added before each Write() call. * * @param label std::string containing a label for this meta value * @param data std::string containing meta data related to the log data * @param skip bool flag if this value should be skipped/ignored in stream * operations (default false) */ virtual void AddMeta(const std::string &label, const std::string &data, bool skip = false) { if (log_meta) { metadata->AddMeta(label, data, skip); } } void AddMetaCopy(LogMetaData::Ptr mdc) { metadata = mdc->Duplicate(); } protected: bool timestamp = true; bool log_meta = true; LogMetaData::Ptr metadata = nullptr; bool prepend_prefix = true; /** * Writes log data and an optional LogTag to the log destination * * This is a pure virtual method which must be implemented. * * If the LogTag is nullptr, the implementation MUST accept this * and just ignore whatever information this object could carry. * * @param logtag LogTag object details * @param data std::string of data to be written * @param colour_init std::string to be printed before log data, to * set the proper colours. Empty by default. * @param colour_reset std::string to be printed after the log data * to reset colour selection. Empty by default. */ virtual void WriteLogLine(LogTag::Ptr logtag, const std::string &data, const std::string &colour_init = "", const std::string &colour_reset = "") = 0; /** * Writes log data to the destination buffer, but will prefix * log lines with information about the log group and log category. * * If logtag points at a LogTag object (not nullptr), this information * will be included in the logged data. * * @param logtag LogTag object details * @param grp LogGroup the log message belongs to * @param ctg LogCategory the log message is categorized as * @param data std::string containing the log data * @param colour_init (optional) std::string to be printed before log * data, to set the proper colours. Emtpy by default. * @param colour_reset (optional) std::string to be printed after the log * data to reset colour selection. Emtpy by default. */ virtual void WriteLogLine(LogTag::Ptr logtag, const LogGroup grp, const LogCategory ctg, const std::string &data, const std::string &colour_init = "", const std::string &colour_reset = "") { WriteLogLine(logtag, LogPrefix(grp, ctg) + data, colour_init, colour_reset); } };