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=pod
=head1 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
=head1 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))();
=head1 DESCRIPTION
SSL_CTX_set_info_callback() sets the B<callback> function, that can be used to
obtain state information for SSL objects created from B<ctx> during connection
setup and use. The setting for B<ctx> is overridden from the setting for
a specific SSL object, if specified.
When B<callback> is NULL, not callback function is used.
SSL_set_info_callback() sets the B<callback> function, that can be used to
obtain state information for B<ssl> during connection setup and use.
When B<callback> is NULL, the callback setting currently valid for
B<ctx> is used.
SSL_CTX_get_info_callback() returns a pointer to the currently set information
callback function for B<ctx>.
SSL_get_info_callback() returns a pointer to the currently set information
callback function for B<ssl>.
=head1 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 B<callback(SSL *ssl, int where, int ret)>.
The B<where> argument specifies information about where (in which context)
the callback function was called. If B<ret> is 0, an error condition occurred.
If an alert is handled, SSL_CB_ALERT is set and B<ret> specifies the alert
information.
B<where> is a bitmask made up of the following bits:
=over 4
=item SSL_CB_LOOP
Callback has been called to indicate state change inside a loop.
=item 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.)
=item SSL_CB_READ
Callback has been called during read operation.
=item SSL_CB_WRITE
Callback has been called during write operation.
=item SSL_CB_ALERT
Callback has been called due to an alert being sent or received.
=item SSL_CB_READ_ALERT (SSL_CB_ALERT|SSL_CB_READ)
=item SSL_CB_WRITE_ALERT (SSL_CB_ALERT|SSL_CB_WRITE)
=item SSL_CB_ACCEPT_LOOP (SSL_ST_ACCEPT|SSL_CB_LOOP)
=item SSL_CB_ACCEPT_EXIT (SSL_ST_ACCEPT|SSL_CB_EXIT)
=item SSL_CB_CONNECT_LOOP (SSL_ST_CONNECT|SSL_CB_LOOP)
=item SSL_CB_CONNECT_EXIT (SSL_ST_CONNECT|SSL_CB_EXIT)
=item SSL_CB_HANDSHAKE_START
Callback has been called because a new handshake is started.
=item SSL_CB_HANDSHAKE_DONE 0x20
Callback has been called because a handshake is finished.
=back
The current state information can be obtained using the
L<SSL_state_string(3)|SSL_state_string(3)> family of functions.
The B<ret> information can be evaluated using the
L<SSL_alert_type_string(3)|SSL_alert_type_string(3)> family of functions.
=head1 RETURN VALUES
SSL_set_info_callback() does not provide diagnostic information.
SSL_get_info_callback() returns the current setting.
=head1 EXAMPLES
The following example callback function prints state strings, information
about alerts being handled and error messages to the B<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));
}
}
}
=head1 SEE ALSO
L<ssl(3)|ssl(3)>, L<SSL_state_string(3)|SSL_state_string(3)>,
L<SSL_alert_type_string(3)|SSL_alert_type_string(3)>
=cut