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SSL_CTX_set_info_callback(3)
Contents
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SSL_CTX_set_info_callback, SSL_CTX_get_info_callback,
SSL_set_info_callback, SSL_get_info_callback - handle
information callback for SSL connections
libcrypto, -lcrypto
#include <openssl/ssl.h>
void SSL_CTX_set_info_callback(SSL_CTX *ctx, void (*callback)());
void (*SSL_CTX_get_info_callback(SSL_CTX *ctx))();
void SSL_set_info_callback(SSL *ssl, void (*callback)());
void (*SSL_get_info_callback(SSL *ssl))();
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:
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_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.
SSL_CB_HANDSHAKE_DONE 0x20
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.
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 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));
}
}
}
ssl(3), SSL_state_string(3), SSL_alert_type_string(3)
2002-08-05 0.9.6g SSL_CTX_set_info_callback(3)
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