There is a good amount of content on how SSL works. This was one I read on medium.

SSL provides many modes of verification of certificates between a client and server during the handshake. Read the details here.

SSL_VERIFY_NONE is the most basic handshake. Here the server will not send a request to the client for its certificate. The server will send a certificate, which the client can verify. Here, we just ignore the certificate as it is self-signed. In this mode of operation, the authenticity of client or server cannot be verified, but we can be assured of secure communication once the handshake is complete. This mode is open to MITM attack.

This tutorial requires openssl-dev to be installed in the system

mkdir build
cd build
cmake ..
make

tlsdemo [-c] [-s 'message to send']
    -c set to enable client mode
    -s 'send the message in quotes'
    -m mode not implemented yet

• Handle readv and writev
• Authenticate both client and server