SSL_CTX_set_info_callback, SSL_CTX_get_info_callback, SSL_set_info_callback, SSL_get_info_callback — handle information callback for SSL connections
SSL_CTX_set_info_callback(SSL_CTX *ctx, void (*callback)());
*ssl, void (*callback)());
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:
Callback has been called to indicate state change inside a
Callback has been called to indicate error exit of a handshake
function. (May be soft error with retry option for non-blocking
Callback has been called during read operation.
Callback has been called during write operation.
Callback has been called due to an alert being sent or received.
Callback has been called because a new handshake is started.
Callback has been called because a handshake is finished.
The current state information can be obtained using the SSL_state_string(3) family
The ret information can be evaluated using the SSL_alert_type_string(3) family
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
void apps_ssl_info_callback(SSL *s, int where, int ret)
const char *str;
if (w & SSL_ST_CONNECT) str="SSL_connect";
else if (w & SSL_ST_ACCEPT) str="SSL_accept";
if (where & SSL_CB_LOOP)
else if (where & SSL_CB_ALERT)
str=(where & SSL_CB_READ)?"read":"write";
BIO_printf(bio_err,"SSL3 alert %s:%s:%s\n",
else if (where & SSL_CB_EXIT)
if (ret == 0)
BIO_printf(bio_err,"%s:failed in %s\n",
else if (ret < 0)
BIO_printf(bio_err,"%s:error in %s\n",
ssl(3), SSL_state_string(3), SSL_alert_type_string(3)