Openssl 1.1.0h

doc/ssl/SSL_CTX_new.pod

@@ -0,0 +1,218 @@
+=pod
+
+=head1 NAME
+
+TLSv1_2_method, TLSv1_2_server_method, TLSv1_2_client_method,
+SSL_CTX_new, SSL_CTX_up_ref, SSLv3_method, SSLv3_server_method,
+SSLv3_client_method, TLSv1_method, TLSv1_server_method, TLSv1_client_method,
+TLSv1_1_method, TLSv1_1_server_method, TLSv1_1_client_method, TLS_method,
+TLS_server_method, TLS_client_method, SSLv23_method, SSLv23_server_method,
+SSLv23_client_method, DTLS_method, DTLS_server_method, DTLS_client_method,
+DTLSv1_method, DTLSv1_server_method, DTLSv1_client_method,
+DTLSv1_2_method, DTLSv1_2_server_method, DTLSv1_2_client_method
+- create a new SSL_CTX object as framework for TLS/SSL or DTLS enabled
+functions
+
+=head1 SYNOPSIS
+
+ #include <openssl/ssl.h>
+
+ SSL_CTX *SSL_CTX_new(const SSL_METHOD *method);
+ int SSL_CTX_up_ref(SSL_CTX *ctx);
+
+ const SSL_METHOD *TLS_method(void);
+ const SSL_METHOD *TLS_server_method(void);
+ const SSL_METHOD *TLS_client_method(void);
+
+ const SSL_METHOD *SSLv23_method(void);
+ const SSL_METHOD *SSLv23_server_method(void);
+ const SSL_METHOD *SSLv23_client_method(void);
+
+ #ifndef OPENSSL_NO_SSL3_METHOD
+ const SSL_METHOD *SSLv3_method(void);
+ const SSL_METHOD *SSLv3_server_method(void);
+ const SSL_METHOD *SSLv3_client_method(void);
+ #endif
+
+ #ifndef OPENSSL_NO_TLS1_METHOD
+ const SSL_METHOD *TLSv1_method(void);
+ const SSL_METHOD *TLSv1_server_method(void);
+ const SSL_METHOD *TLSv1_client_method(void);
+ #endif
+
+ #ifndef OPENSSL_NO_TLS1_1_METHOD
+ const SSL_METHOD *TLSv1_1_method(void);
+ const SSL_METHOD *TLSv1_1_server_method(void);
+ const SSL_METHOD *TLSv1_1_client_method(void);
+ #endif
+
+ #ifndef OPENSSL_NO_TLS1_2_METHOD
+ const SSL_METHOD *TLSv1_2_method(void);
+ const SSL_METHOD *TLSv1_2_server_method(void);
+ const SSL_METHOD *TLSv1_2_client_method(void);
+ #endif
+
+ const SSL_METHOD *DTLS_method(void);
+ const SSL_METHOD *DTLS_server_method(void);
+ const SSL_METHOD *DTLS_client_method(void);
+
+ #ifndef OPENSSL_NO_DTLS1_METHOD
+ const SSL_METHOD *DTLSv1_method(void);
+ const SSL_METHOD *DTLSv1_server_method(void);
+ const SSL_METHOD *DTLSv1_client_method(void);
+ #endif
+
+ #ifndef OPENSSL_NO_DTLS1_2_METHOD
+ const SSL_METHOD *DTLSv1_2_method(void);
+ const SSL_METHOD *DTLSv1_2_server_method(void);
+ const SSL_METHOD *DTLSv1_2_client_method(void);
+ #endif
+
+=head1 DESCRIPTION
+
+SSL_CTX_new() creates a new B<SSL_CTX> object as framework to
+establish TLS/SSL or DTLS enabled connections. An B<SSL_CTX> object is
+reference counted. Creating an B<SSL_CTX> object for the first time increments
+the reference count. Freeing it (using SSL_CTX_free) decrements it. When the
+reference count drops to zero, any memory or resources allocated to the
+B<SSL_CTX> object are freed. SSL_CTX_up_ref() increments the reference count for
+an existing B<SSL_CTX> structure.
+
+=head1 NOTES
+
+The SSL_CTX object uses B<method> as connection method.
+The methods exist in a generic type (for client and server use), a server only
+type, and a client only type.
+B<method> can be of the following types:
+
+=over 4
+
+=item TLS_method(), TLS_server_method(), TLS_client_method()
+
+These are the general-purpose I<version-flexible> SSL/TLS methods.
+The actual protocol version used will be negotiated to the highest version
+mutually supported by the client and the server.
+The supported protocols are SSLv3, TLSv1, TLSv1.1 and TLSv1.2.
+Applications should use these methods, and avoid the version-specific
+methods described below.
+
+=item SSLv23_method(), SSLv23_server_method(), SSLv23_client_method()
+
+Use of these functions is deprecated. They have been replaced with the above
+TLS_method(), TLS_server_method() and TLS_client_method() respectively. New
+code should use those functions instead.
+
+=item TLSv1_2_method(), TLSv1_2_server_method(), TLSv1_2_client_method()
+
+A TLS/SSL connection established with these methods will only understand the
+TLSv1.2 protocol.
+
+=item TLSv1_1_method(), TLSv1_1_server_method(), TLSv1_1_client_method()
+
+A TLS/SSL connection established with these methods will only understand the
+TLSv1.1 protocol.
+
+=item TLSv1_method(), TLSv1_server_method(), TLSv1_client_method()
+
+A TLS/SSL connection established with these methods will only understand the
+TLSv1 protocol.
+
+=item SSLv3_method(), SSLv3_server_method(), SSLv3_client_method()
+
+A TLS/SSL connection established with these methods will only understand the
+SSLv3 protocol.
+The SSLv3 protocol is deprecated and should not be used.
+
+=item DTLS_method(), DTLS_server_method(), DTLS_client_method()
+
+These are the version-flexible DTLS methods.
+Currently supported protocols are DTLS 1.0 and DTLS 1.2.
+
+=item DTLSv1_2_method(), DTLSv1_2_server_method(), DTLSv1_2_client_method()
+
+These are the version-specific methods for DTLSv1.2.
+
+=item DTLSv1_method(), DTLSv1_server_method(), DTLSv1_client_method()
+
+These are the version-specific methods for DTLSv1.
+
+=back
+
+SSL_CTX_new() initializes the list of ciphers, the session cache setting, the
+callbacks, the keys and certificates and the options to their default values.
+
+TLS_method(), TLS_server_method(), TLS_client_method(), DTLS_method(),
+DTLS_server_method() and DTLS_client_method() are the I<version-flexible>
+methods.
+All other methods only support one specific protocol version.
+Use the I<version-flexible> methods instead of the version specific methods.
+
+If you want to limit the supported protocols for the version flexible
+methods you can use L<SSL_CTX_set_min_proto_version(3)>,
+L<SSL_set_min_proto_version(3)>, L<SSL_CTX_set_max_proto_version(3)> and
+L<SSL_set_max_proto_version(3)> functions.
+Using these functions it is possible to choose e.g. TLS_server_method()
+and be able to negotiate with all possible clients, but to only
+allow newer protocols like TLS 1.0, TLS 1.1 or TLS 1.2.
+
+The list of protocols available can also be limited using the
+B<SSL_OP_NO_SSLv3>, B<SSL_OP_NO_TLSv1>, B<SSL_OP_NO_TLSv1_1> and
+B<SSL_OP_NO_TLSv1_2> options of the L<SSL_CTX_set_options(3)> or
+L<SSL_set_options(3)> functions, but this approach is not recommended.
+Clients should avoid creating "holes" in the set of protocols they support.
+When disabling a protocol, make sure that you also disable either all previous
+or all subsequent protocol versions.
+In clients, when a protocol version is disabled without disabling I<all>
+previous protocol versions, the effect is to also disable all subsequent
+protocol versions.
+
+The SSLv3 protocol is deprecated and should generally not be used.
+Applications should typically use L<SSL_CTX_set_min_proto_version(3)> to set
+the minimum protocol to at least B<TLS1_VERSION>.
+
+=head1 RETURN VALUES
+
+The following return values can occur:
+
+=over 4
+
+=item NULL
+
+The creation of a new SSL_CTX object failed. Check the error stack to find out
+the reason.
+
+=item Pointer to an SSL_CTX object
+
+The return value points to an allocated SSL_CTX object.
+
+SSL_CTX_up_ref() returns 1 for success and 0 for failure.
+
+=back
+
+=head1 HISTORY
+
+Support for SSLv2 and the corresponding SSLv2_method(),
+SSLv2_server_method() and SSLv2_client_method() functions where
+removed in OpenSSL 1.1.0.
+
+SSLv23_method(), SSLv23_server_method() and SSLv23_client_method()
+were deprecated and the preferred TLS_method(), TLS_server_method()
+and TLS_client_method() functions were introduced in OpenSSL 1.1.0.
+
+All version-specific methods were deprecated in OpenSSL 1.1.0.
+
+=head1 SEE ALSO
+
+L<SSL_CTX_set_options(3)>, L<SSL_CTX_free(3)>, L<SSL_accept(3)>,
+L<SSL_CTX_set_min_proto_version(3)>, L<ssl(3)>, L<SSL_set_connect_state(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