NAME
SSL_CTX_set_info_callback,
SSL_CTX_get_info_callback,
SSL_set_info_callback,
SSL_get_info_callback —
handle information callback for SSL
connections
SYNOPSIS
#include
<openssl/ssl.h>
void
SSL_CTX_set_info_callback(SSL_CTX
*ctx, void (*callback)(const SSL *ssl, int where, int
ret));
void
(*SSL_CTX_get_info_callback(const SSL_CTX
*ctx))(const SSL *ssl, int
where, int ret);
void
SSL_set_info_callback(SSL *ssl,
void (*callback)(const SSL *ssl, int where, int
ret));
void
(*SSL_get_info_callback(const SSL
*ssl))(const SSL *ssl, int
where, int ret);
DESCRIPTION
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, 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 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:
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_ALERTSSL_CB_WRITE_ALERTSSL_CB_ACCEPT_LOOPSSL_CB_ACCEPT_EXITSSL_CB_CONNECT_LOOPSSL_CB_CONNECT_EXITSSL_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 VALUES
SSL_CTX_get_info_callback() and
SSL_get_info_callback() return a pointer to the
current callback or NULL if none is set.
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 ALSO
HISTORY
These functions first appeared in SSLeay 0.6.0 and have been available since OpenBSD 2.4.