Design and development of the configuration parser module for the new agent

[TomasTurina]

Description

As part of the development of the new agent MVP, it is necessary to develop a new configuration parser module.

Take into account the following:

• Configuration will be in TOML format.
  • The name of the configuration file will be wazuh.conf.
• Avoid to create a new library for this.
  • Select and use a common and maintained library, mention the advantages and disadvantages of its use.
• This module should be able to parse and save the configuration in memory.
  • Consider STL containers to do this.
• This module should be able to distribute all configuration to all modules.
  • Each module will be in charge of reading and applying its particular configuration.

[Nicogp]

Libraries investigation

The official TOML Wiki lists three C++ libraries:

• toml11
• tomlcpp
• toml++

toml11

Documentation
Recent activity in the repository.
Licence: MIT
Standar: C++11/14/17/20
Features:

• It complies with the latest TOML language specification.
• It supports new features merged into the upcoming TOML version (v1.1.0).
• It provides clear error messages, including the location of the error.
• It parses and retains comments, associating them with corresponding values.
• It provides exception-less parse function.
• It supports complex type conversions from TOML values.
• It allows customization of the types stored in toml::value.

tomlcpp

Documentation (Only a Readme)
Last update: two years ago.
Licence: MIT
Standar: This is a C++ wrapper around the C library available here: https://github.com/cktan/tomlc99.
Features:

• Compatible with TOML v1.0.0.

• Does not throw C++ exceptions.

• Provides very simple and intuitive interface.

toml++

Documentation
Last update: 4 months ago.
Licence: MIT
Standar: C++17 (plus some C++20 features where available, e.g. experimental support for [char8_t]
Features:

• Header-only (optional!)
• Supports the latest TOML release (v1.0.0), plus optional support for some unreleased TOML features
• Supports serializing to JSON and YAML
• Proper UTF-8 handling (incl. BOM)
• C++17 (plus some C++20 features where available, e.g. experimental support for char8_t strings)
• Doesn't require RTTI
• Works with or without exceptions
• Tested on x64, x86 and ARM