Document the i2o and o2i SCT functions

[openssl.git] / doc / ssl / SSL_clear.pod

diff --git a/doc/ssl/SSL_clear.pod b/doc/ssl/SSL_clear.pod
index 862fd8291df18dcd4adc19077d3fcdee76e3e1ac..ed0ad60cbea5cd9e9898c172b9ce6dcded3e0c39 100644 (file)
--- a/doc/ssl/SSL_clear.pod
+++ b/doc/ssl/SSL_clear.pod
@@ -13,8 +13,42 @@ SSL_clear - reset SSL object to allow another connection
 =head1 DESCRIPTION
 
 Reset B<ssl> to allow another connection. All settings (method, ciphers,
-BIOs) are kept. A completely negotiated B<SSL_SESSION> is not freed but left
-untouched for the underlying B<SSL_CTX>.
+BIOs) are kept.
+
+=head1 NOTES
+
+SSL_clear is used to prepare an SSL object for a new connection. While all
+settings are kept, a side effect is the handling of the current SSL session.
+If a session is still B<open>, it is considered bad and will be removed
+from the session cache, as required by RFC2246. A session is considered open,
+if L<SSL_shutdown(3)> was not called for the connection
+or at least L<SSL_set_shutdown(3)> was used to
+set the SSL_SENT_SHUTDOWN state.
+
+If a session was closed cleanly, the session object will be kept and all
+settings corresponding. This explicitly means, that e.g. the special method
+used during the session will be kept for the next handshake. So if the
+session was a TLSv1 session, a SSL client object will use a TLSv1 client
+method for the next handshake and a SSL server object will use a TLSv1
+server method, even if TLS_*_methods were chosen on startup. This
+will might lead to connection failures (see L<SSL_new(3)>)
+for a description of the method's properties.
+
+=head1 WARNINGS
+
+SSL_clear() resets the SSL object to allow for another connection. The
+reset operation however keeps several settings of the last sessions
+(some of these settings were made automatically during the last
+handshake). It only makes sense for a new connection with the exact
+same peer that shares these settings, and may fail if that peer
+changes its settings between connections. Use the sequence
+L<SSL_get_session(3)>;
+L<SSL_new(3)>;
+L<SSL_set_session(3)>;
+L<SSL_free(3)>
+instead to avoid such failures
+(or simply L<SSL_free(3)>; L<SSL_new(3)>
+if session reuse is not desired).
 
 =head1 RETURN VALUES
 
@@ -22,18 +56,29 @@ The following return values can occur:
 
 =over 4
 
-=item 0
+=item Z<>0
 
 The SSL_clear() operation could not be performed. Check the error stack to
 find out the reason.
 
-=item 1
+=item Z<>1
 
 The SSL_clear() operation was successful.
 
 =back
 
-L<SSL_new(3)|SSL_new(3)>, L<SSL_free(3)|SSL_free(3)>,
-L<ssl(3)|ssl(3)>
+L<SSL_new(3)>, L<SSL_free(3)>,
+L<SSL_shutdown(3)>, L<SSL_set_shutdown(3)>,
+L<SSL_CTX_set_options(3)>, L<ssl(3)>,
+L<SSL_CTX_set_client_cert_cb(3)>
+
+=head1 COPYRIGHT
+
+Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved.
+
+Licensed under the OpenSSL license (the "License").  You may not use
+this file except in compliance with the License.  You can obtain a copy
+in the file LICENSE in the source distribution or at
+L<https://www.openssl.org/source/license.html>.
 
 =cut