internal handling functions for SSL_CTX and SSL objects
SSL_CTX_ctrl, SSL_ctrl, SSL_callback_ctrl
long SSL_CTX_ctrl(SSL_CTX *ctx, int cmd, long larg, void *parg);
long SSL_CTX_callback_ctrl(SSL_CTX *, int cmd, void (*fp)());
long SSL_ctrl(SSL *ssl, int cmd, long larg, void *parg);
long SSL_callback_ctrl(SSL *, int cmd, void (*fp)());
The SSL_*_ctrl() family of functions is used to manipulate settings of
the SSL_CTX and SSL objects. Depending on the command cmd the arguments
larg, parg, or fp are evaluated. These functions should never
be called directly. All functionalities needed are made available via
other functions or macros.
The return values of the SSL*_ctrl() functions depend on the command
supplied via the cmd parameter.