167 lines
5.1 KiB
Plaintext
167 lines
5.1 KiB
Plaintext
=pod
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=head1 NAME
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SSL_CTX_set_info_callback,
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SSL_CTX_get_info_callback,
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SSL_set_info_callback,
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SSL_get_info_callback
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- handle information callback for SSL connections
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=head1 SYNOPSIS
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#include <openssl/ssl.h>
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void SSL_CTX_set_info_callback(SSL_CTX *ctx, void (*callback)());
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void (*SSL_CTX_get_info_callback(const SSL_CTX *ctx))();
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void SSL_set_info_callback(SSL *ssl, void (*callback)());
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void (*SSL_get_info_callback(const SSL *ssl))();
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=head1 DESCRIPTION
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SSL_CTX_set_info_callback() sets the B<callback> function, that can be used to
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obtain state information for SSL objects created from B<ctx> during connection
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setup and use. The setting for B<ctx> is overridden from the setting for
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a specific SSL object, if specified.
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When B<callback> is NULL, no callback function is used.
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SSL_set_info_callback() sets the B<callback> function, that can be used to
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obtain state information for B<ssl> during connection setup and use.
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When B<callback> is NULL, the callback setting currently valid for
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B<ctx> is used.
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SSL_CTX_get_info_callback() returns a pointer to the currently set information
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callback function for B<ctx>.
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SSL_get_info_callback() returns a pointer to the currently set information
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callback function for B<ssl>.
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=head1 NOTES
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When setting up a connection and during use, it is possible to obtain state
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information from the SSL/TLS engine. When set, an information callback function
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is called whenever a significant event occurs such as: the state changes,
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an alert appears, or an error occurs.
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The callback function is called as B<callback(SSL *ssl, int where, int ret)>.
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The B<where> argument specifies information about where (in which context)
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the callback function was called. If B<ret> is 0, an error condition occurred.
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If an alert is handled, SSL_CB_ALERT is set and B<ret> specifies the alert
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information.
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B<where> is a bit mask made up of the following bits:
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=over 4
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=item SSL_CB_LOOP
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Callback has been called to indicate state change or some other significant
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state machine event. This may mean that the callback gets invoked more than once
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per state in some situations.
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=item SSL_CB_EXIT
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Callback has been called to indicate exit of a handshake function. This will
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happen after the end of a handshake, but may happen at other times too such as
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on error or when IO might otherwise block and nonblocking is being used.
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=item SSL_CB_READ
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Callback has been called during read operation.
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=item SSL_CB_WRITE
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Callback has been called during write operation.
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=item SSL_CB_ALERT
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Callback has been called due to an alert being sent or received.
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=item SSL_CB_READ_ALERT (SSL_CB_ALERT|SSL_CB_READ)
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=item SSL_CB_WRITE_ALERT (SSL_CB_ALERT|SSL_CB_WRITE)
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=item SSL_CB_ACCEPT_LOOP (SSL_ST_ACCEPT|SSL_CB_LOOP)
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=item SSL_CB_ACCEPT_EXIT (SSL_ST_ACCEPT|SSL_CB_EXIT)
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=item SSL_CB_CONNECT_LOOP (SSL_ST_CONNECT|SSL_CB_LOOP)
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=item SSL_CB_CONNECT_EXIT (SSL_ST_CONNECT|SSL_CB_EXIT)
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=item SSL_CB_HANDSHAKE_START
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Callback has been called because a new handshake is started. It also occurs when
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resuming a handshake following a pause to handle early data.
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=item SSL_CB_HANDSHAKE_DONE
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Callback has been called because a handshake is finished. It also occurs if the
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handshake is paused to allow the exchange of early data.
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=back
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The current state information can be obtained using the
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L<SSL_state_string(3)> family of functions.
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The B<ret> information can be evaluated using the
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L<SSL_alert_type_string(3)> family of functions.
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=head1 RETURN VALUES
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SSL_set_info_callback() does not provide diagnostic information.
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SSL_get_info_callback() returns the current setting.
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=head1 EXAMPLES
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The following example callback function prints state strings, information
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about alerts being handled and error messages to the B<bio_err> BIO.
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void apps_ssl_info_callback(SSL *s, int where, int ret)
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{
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const char *str;
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int w = where & ~SSL_ST_MASK;
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if (w & SSL_ST_CONNECT)
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str = "SSL_connect";
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else if (w & SSL_ST_ACCEPT)
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str = "SSL_accept";
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else
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str = "undefined";
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if (where & SSL_CB_LOOP) {
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BIO_printf(bio_err, "%s:%s\n", str, SSL_state_string_long(s));
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} else if (where & SSL_CB_ALERT) {
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str = (where & SSL_CB_READ) ? "read" : "write";
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BIO_printf(bio_err, "SSL3 alert %s:%s:%s\n", str,
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SSL_alert_type_string_long(ret),
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SSL_alert_desc_string_long(ret));
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} else if (where & SSL_CB_EXIT) {
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if (ret == 0) {
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BIO_printf(bio_err, "%s:failed in %s\n",
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str, SSL_state_string_long(s));
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} else if (ret < 0) {
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BIO_printf(bio_err, "%s:error in %s\n",
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str, SSL_state_string_long(s));
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}
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}
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}
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=head1 SEE ALSO
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L<ssl(7)>, L<SSL_state_string(3)>,
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L<SSL_alert_type_string(3)>
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=head1 COPYRIGHT
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Copyright 2001-2020 The OpenSSL Project Authors. All Rights Reserved.
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Licensed under the OpenSSL license (the "License"). You may not use
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this file except in compliance with the License. You can obtain a copy
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in the file LICENSE in the source distribution or at
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L<https://www.openssl.org/source/license.html>.
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=cut
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