/usr/man/cat.3/SSL_CTX_set_info_callback.3

SSL_CTX_set_info_callback(3) OpenSSL SSL_CTX_set_info_callback(3)

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)());
      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))();

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,
     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.

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 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.

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SSL_CTX_set_info_callback(3) OpenSSL SSL_CTX_set_info_callback(3)

     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.

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(SSL *s, int where, int ret)
             {
             const char *str;
             int w;

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SSL_CTX_set_info_callback(3) OpenSSL SSL_CTX_set_info_callback(3)

             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(3), SSL_state_string(3), SSL_alert_type_string(3)

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See also SSL_CTX_get_info_callback(3)
See also SSL_get_info_callback(3)
See also SSL_set_info_callback(3)