HP Open Source Security for OpenVMS Volume 2: HP SSL for OpenVMS > SSL Application Programming Interface (API)
SSL_CTX_set_info_callback() sets the callback function, that can be used to obtain state information for SSL objects created from ctx during connection setup and use. The setting for ctx is overridden from the setting for a specific SSL object, if specified. When callback is NULL, not callback function is used.
SSL_set_info_callback() sets the callback function, that can be used to obtain state information for ssl during connection setup and use. When callback is NULL, the callback setting currently valid for ctx is used.
SSL_CTX_get_info_callback() returns a pointer to the currently set information callback function for ctx.
SSL_get_info_callback() returns a pointer to the currently set information callback function for ssl.
When setting up a connection and during use, it is possible to obtain state information from the SSL/TLS engine. When set, an information callback function is called whenever the state changes, an alert appears, or an error occurs.
The callback function is called as callback(SSL *ssl, int where, int ret). The where argument specifies information about where (in which context) the callback function was called. If ret is 0, an error condition occurred. If an alert is handled, SSL_CB_ALERT is set and ret specifies the alert information.
where is a bitmask made up of the following bits:
The current state information can be obtained using the SSL_state_string(3) family of functions.
The ret information can be evaluated using the SSL_alert_type_string(3) family of functions.
SSL_set_info_callback() does not provide diagnostic information.
SSL_get_info_callback() returns the current setting.
The following example callback function prints state strings, information about alerts being handled and error messages to the bio_err BIO.