SSL_CTX_SET_INFO_CALL... BSD Library Functions Manual SSL_CTX_SET_INFO_CALL...NAME
SSL_CTX_set_info_callback, SSL_CTX_get_info_callback,
SSL_set_info_callback, SSL_get_info_callback — handle information call‐
back for SSL connections
SYNOPSIS
#include <openssl/ssl.h>
void
SSL_CTX_set_info_callback(SSL_CTX *ctx, void (*callback)());
void
(*SSL_CTX_get_info_callback(const SSL_CTX *ctx))();
void
SSL_set_info_callback(SSL *ssl, void (*callback)());
void
(*SSL_get_info_callback(const SSL *ssl))();
DESCRIPTIONSSL_CTX_set_info_callback() sets the callback function that can be used
to obtain state information for SSL objects created from ctx during con‐
nection setup and use. The setting for ctx is overridden from the set‐
ting for a specific SSL object, if specified. When callback is NULL, no
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 infor‐
mation callback function for ctx.
SSL_get_info_callback() returns a pointer to the currently set informa‐
tion callback function for ssl.
NOTES
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 condi‐
tion occurred. If an alert is handled, SSL_CB_ALERT is set and ret spec‐
ifies the alert information.
where is a bitmask made up of the following bits:
SSL_CB_LOOP
Callback has been called to indicate state change inside a loop.
SSL_CB_EXIT
Callback has been called to indicate error exit of a handshake
function. (May be soft error with retry option for non-blocking
setups.)
SSL_CB_READ
Callback has been called during read operation.
SSL_CB_WRITE
Callback has been called during write operation.
SSL_CB_ALERT
Callback has been called due to an alert being sent or received.
SSL_CB_READ_ALERT
SSL_CB_WRITE_ALERT
SSL_CB_ACCEPT_LOOP
SSL_CB_ACCEPT_EXIT
SSL_CB_CONNECT_LOOP
SSL_CB_CONNECT_EXIT
SSL_CB_HANDSHAKE_START
Callback has been called because a new handshake is started.
SSL_CB_HANDSHAKE_DONE
Callback has been called because a handshake is finished.
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.
RETURN VALUESSSL_set_info_callback() does not provide diagnostic information.
SSL_get_info_callback() returns the current setting.
EXAMPLES
The following example callback function prints state strings, information
about alerts being handled and error messages to the bio_err BIO.
void
apps_ssl_info_callback(SSL *s, int where, int ret)
{
const char *str;
int w;
w = where & ~SSL_ST_MASK;
if (w & SSL_ST_CONNECT)
str = "SSL_connect";
else if (w & SSL_ST_ACCEPT)
str = "SSL_accept";
else
str = "undefined";
if (where & SSL_CB_LOOP) {
BIO_printf(bio_err, "%s:%s\n", str,
SSL_state_string_long(s));
} else if (where & SSL_CB_ALERT) {
str = (where & SSL_CB_READ) ? "read" : "write";
BIO_printf(bio_err, "SSL3 alert %s:%s:%s\n", str,
SSL_alert_type_string_long(ret),
SSL_alert_desc_string_long(ret));
} else if (where & SSL_CB_EXIT) {
if (ret == 0)
BIO_printf(bio_err, "%s:failed in %s\n",
str, SSL_state_string_long(s));
else if (ret < 0) {
BIO_printf(bio_err, "%s:error in %s\n",
str, SSL_state_string_long(s));
}
}
}
SEE ALSOssl(3), SSL_alert_type_string(3), SSL_state_string(3)BSD April 26, 2024 BSD
