SSL_CTX_SET_INFO_CALLBACK(3ossl) OpenSSL SSL_CTX_SET_INFO_CALLBACK(3ossl)
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 type, int val));
void (*SSL_CTX_get_info_callback(SSL_CTX *ctx)) (const SSL *ssl, int type, int val);
void SSL_set_info_callback(SSL *ssl,
void (*callback) (const SSL *ssl, int type, int val));
void (*SSL_get_info_callback(const SSL *ssl)) (const SSL *ssl, int type, int val);
DESCRIPTION
SSL_CTX_set_info_callback(3) 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.
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 a significant event occurs such
as: 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 bit-mask made up of the following bits:
SSL_CB_LOOP
Callback has been called to indicate state change or some other
significant state machine event. This may mean that the callback
gets invoked more than once per state in some situations.
SSL_CB_EXIT
Callback has been called to indicate exit of a handshake function.
This will happen after the end of a handshake, but may happen at
other times too such as on error or when IO might otherwise block
and nonblocking is being used.
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_ALERT|SSL_CB_READ)
SSL_CB_WRITE_ALERT (SSL_CB_ALERT|SSL_CB_WRITE)
SSL_CB_ACCEPT_LOOP (SSL_ST_ACCEPT|SSL_CB_LOOP)
SSL_CB_ACCEPT_EXIT (SSL_ST_ACCEPT|SSL_CB_EXIT)
SSL_CB_CONNECT_LOOP (SSL_ST_CONNECT|SSL_CB_LOOP)
SSL_CB_CONNECT_EXIT (SSL_ST_CONNECT|SSL_CB_EXIT)
SSL_CB_HANDSHAKE_START
Callback has been called because a new handshake is started. It
also occurs when resuming a handshake following a pause to handle
early data.
SSL_CB_HANDSHAKE_DONE
Callback has been called because a handshake is finished. It also
occurs if the handshake is paused to allow the exchange of early
data.
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_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(const SSL *s, int where, int ret)
{
const char *str;
int 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
ssl(7), SSL_state_string(3), SSL_alert_type_string(3)
COPYRIGHT
Copyright 2001-2020 The OpenSSL Project Authors. All Rights Reserved.
Licensed under the Apache License 2.0 (the "License"). You may not use
this file except in compliance with the License. You can obtain a copy
in the file LICENSE in the source distribution or at
<https://www.openssl.org/source/license.html>.
3.3.2 2024-09-04 SSL_CTX_SET_INFO_CALLBACK(3ossl)
openssl 3.3.2 - Generated Tue Sep 24 07:20:16 CDT 2024