SSL_CTX_set_info_callback(3)

     SSL_CTX_set_info_callba0.9.6h (2001-1SSL_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(SSL_CTX *ctx))();

           void SSL_set_info_callback(SSL *ssl, void (*callback)());
           void (*SSL_get_info_callback(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_callba0.9.6h (2001-1SSL_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;

                  w=where& ~SSL_ST_MASK;

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     SSL_CTX_set_info_callba0.9.6h (2001-1SSL_CTX_set_info_callback(3)

                  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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