This package contains a number of advanced stream types, including TLS server and client support.
If the version VibeKeylogFromEnvironment is specified as a build parameter, and the feature is supported (requires openssl version 1.1.1 or later), then the library will examine the environment variable SSLKEYLOGFILE for a path to write all keys to.
This is handy for use with the wireshark tool for inspecting traffic. See for instance how cURL does this.