SSL_CTX_up_ref(3ssl)

1SSL_CTX_NEW(3)                      OpenSSL                     SSL_CTX_NEW(3)
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NAME

6       TLSv1_2_method, TLSv1_2_server_method, TLSv1_2_client_method,
7       SSL_CTX_new, SSL_CTX_up_ref, SSLv3_method, SSLv3_server_method,
8       SSLv3_client_method, TLSv1_method, TLSv1_server_method,
9       TLSv1_client_method, TLSv1_1_method, TLSv1_1_server_method,
10       TLSv1_1_client_method, TLS_method, TLS_server_method,
11       TLS_client_method, SSLv23_method, SSLv23_server_method,
12       SSLv23_client_method, DTLS_method, DTLS_server_method,
13       DTLS_client_method, DTLSv1_method, DTLSv1_server_method,
14       DTLSv1_client_method, DTLSv1_2_method, DTLSv1_2_server_method,
15       DTLSv1_2_client_method - create a new SSL_CTX object as framework for
16       TLS/SSL or DTLS enabled functions
17

SYNOPSIS

19        #include <openssl/ssl.h>
20
21        SSL_CTX *SSL_CTX_new(const SSL_METHOD *method);
22        int SSL_CTX_up_ref(SSL_CTX *ctx);
23
24        const SSL_METHOD *TLS_method(void);
25        const SSL_METHOD *TLS_server_method(void);
26        const SSL_METHOD *TLS_client_method(void);
27
28        const SSL_METHOD *SSLv23_method(void);
29        const SSL_METHOD *SSLv23_server_method(void);
30        const SSL_METHOD *SSLv23_client_method(void);
31
32        #ifndef OPENSSL_NO_SSL3_METHOD
33        const SSL_METHOD *SSLv3_method(void);
34        const SSL_METHOD *SSLv3_server_method(void);
35        const SSL_METHOD *SSLv3_client_method(void);
36        #endif
37
38        #ifndef OPENSSL_NO_TLS1_METHOD
39        const SSL_METHOD *TLSv1_method(void);
40        const SSL_METHOD *TLSv1_server_method(void);
41        const SSL_METHOD *TLSv1_client_method(void);
42        #endif
43
44        #ifndef OPENSSL_NO_TLS1_1_METHOD
45        const SSL_METHOD *TLSv1_1_method(void);
46        const SSL_METHOD *TLSv1_1_server_method(void);
47        const SSL_METHOD *TLSv1_1_client_method(void);
48        #endif
49
50        #ifndef OPENSSL_NO_TLS1_2_METHOD
51        const SSL_METHOD *TLSv1_2_method(void);
52        const SSL_METHOD *TLSv1_2_server_method(void);
53        const SSL_METHOD *TLSv1_2_client_method(void);
54        #endif
55
56        const SSL_METHOD *DTLS_method(void);
57        const SSL_METHOD *DTLS_server_method(void);
58        const SSL_METHOD *DTLS_client_method(void);
59
60        #ifndef OPENSSL_NO_DTLS1_METHOD
61        const SSL_METHOD *DTLSv1_method(void);
62        const SSL_METHOD *DTLSv1_server_method(void);
63        const SSL_METHOD *DTLSv1_client_method(void);
64        #endif
65
66        #ifndef OPENSSL_NO_DTLS1_2_METHOD
67        const SSL_METHOD *DTLSv1_2_method(void);
68        const SSL_METHOD *DTLSv1_2_server_method(void);
69        const SSL_METHOD *DTLSv1_2_client_method(void);
70        #endif
71

DESCRIPTION

73       SSL_CTX_new() creates a new SSL_CTX object as framework to establish
74       TLS/SSL or DTLS enabled connections. An SSL_CTX object is reference
75       counted. Creating an SSL_CTX object for the first time increments the
76       reference count. Freeing it (using SSL_CTX_free) decrements it. When
77       the reference count drops to zero, any memory or resources allocated to
78       the SSL_CTX object are freed. SSL_CTX_up_ref() increments the reference
79       count for an existing SSL_CTX structure.
80

NOTES

82       The SSL_CTX object uses method as connection method.  The methods exist
83       in a generic type (for client and server use), a server only type, and
84       a client only type.  method can be of the following types:
85
86       TLS_method(), TLS_server_method(), TLS_client_method()
87           These are the general-purpose version-flexible SSL/TLS methods.
88           The actual protocol version used will be negotiated to the highest
89           version mutually supported by the client and the server.  The
90           supported protocols are SSLv3, TLSv1, TLSv1.1, TLSv1.2 and TLSv1.3.
91           Applications should use these methods, and avoid the version-
92           specific methods described below, which are deprecated.
93
94       SSLv23_method(), SSLv23_server_method(), SSLv23_client_method()
95           These functions do not exist anymore, they have been renamed to
96           TLS_method(), TLS_server_method() and TLS_client_method()
97           respectively.  Currently, the old function calls are renamed to the
98           corresponding new ones by preprocessor macros, to ensure that
99           existing code which uses the old function names still compiles.
100           However, using the old function names is deprecated and new code
101           should call the new functions instead.
102
103       TLSv1_2_method(), TLSv1_2_server_method(), TLSv1_2_client_method()
104           A TLS/SSL connection established with these methods will only
105           understand the TLSv1.2 protocol. These methods are deprecated.
106
107       TLSv1_1_method(), TLSv1_1_server_method(), TLSv1_1_client_method()
108           A TLS/SSL connection established with these methods will only
109           understand the TLSv1.1 protocol.  These methods are deprecated.
110
111       TLSv1_method(), TLSv1_server_method(), TLSv1_client_method()
112           A TLS/SSL connection established with these methods will only
113           understand the TLSv1 protocol. These methods are deprecated.
114
115       SSLv3_method(), SSLv3_server_method(), SSLv3_client_method()
116           A TLS/SSL connection established with these methods will only
117           understand the SSLv3 protocol.  The SSLv3 protocol is deprecated
118           and should not be used.
119
120       DTLS_method(), DTLS_server_method(), DTLS_client_method()
121           These are the version-flexible DTLS methods.  Currently supported
122           protocols are DTLS 1.0 and DTLS 1.2.
123
124       DTLSv1_2_method(), DTLSv1_2_server_method(), DTLSv1_2_client_method()
125           These are the version-specific methods for DTLSv1.2.  These methods
126           are deprecated.
127
128       DTLSv1_method(), DTLSv1_server_method(), DTLSv1_client_method()
129           These are the version-specific methods for DTLSv1.  These methods
130           are deprecated.
131
132       SSL_CTX_new() initializes the list of ciphers, the session cache
133       setting, the callbacks, the keys and certificates and the options to
134       their default values.
135
136       TLS_method(), TLS_server_method(), TLS_client_method(), DTLS_method(),
137       DTLS_server_method() and DTLS_client_method() are the version-flexible
138       methods.  All other methods only support one specific protocol version.
139       Use the version-flexible methods instead of the version specific
140       methods.
141
142       If you want to limit the supported protocols for the version flexible
143       methods you can use SSL_CTX_set_min_proto_version(3),
144       SSL_set_min_proto_version(3), SSL_CTX_set_max_proto_version(3) and
145       SSL_set_max_proto_version(3) functions.  Using these functions it is
146       possible to choose e.g. TLS_server_method() and be able to negotiate
147       with all possible clients, but to only allow newer protocols like TLS
148       1.0, TLS 1.1, TLS 1.2 or TLS 1.3.
149
150       The list of protocols available can also be limited using the
151       SSL_OP_NO_SSLv3, SSL_OP_NO_TLSv1, SSL_OP_NO_TLSv1_1, SSL_OP_NO_TLSv1_3,
152       SSL_OP_NO_TLSv1_2 and SSL_OP_NO_TLSv1_3 options of the
153       SSL_CTX_set_options(3) or SSL_set_options(3) functions, but this
154       approach is not recommended. Clients should avoid creating "holes" in
155       the set of protocols they support. When disabling a protocol, make sure
156       that you also disable either all previous or all subsequent protocol
157       versions.  In clients, when a protocol version is disabled without
158       disabling all previous protocol versions, the effect is to also disable
159       all subsequent protocol versions.
160
161       The SSLv3 protocol is deprecated and should generally not be used.
162       Applications should typically use SSL_CTX_set_min_proto_version(3) to
163       set the minimum protocol to at least TLS1_VERSION.
164

RETURN VALUES

166       The following return values can occur:
167
168       NULL
169           The creation of a new SSL_CTX object failed. Check the error stack
170           to find out the reason.
171
172       Pointer to an SSL_CTX object
173           The return value points to an allocated SSL_CTX object.
174
175           SSL_CTX_up_ref() returns 1 for success and 0 for failure.
176

HISTORY

182       Support for SSLv2 and the corresponding SSLv2_method(),
183       SSLv2_server_method() and SSLv2_client_method() functions where removed
184       in OpenSSL 1.1.0.
185
186       SSLv23_method(), SSLv23_server_method() and SSLv23_client_method() were
187       deprecated and the preferred TLS_method(), TLS_server_method() and
188       TLS_client_method() functions were added in OpenSSL 1.1.0.
189
190       All version-specific methods were deprecated in OpenSSL 1.1.0.
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COPYRIGHT

193       Copyright 2000-2019 The OpenSSL Project Authors. All Rights Reserved.
194
195       Licensed under the OpenSSL license (the "License").  You may not use
196       this file except in compliance with the License.  You can obtain a copy
197       in the file LICENSE in the source distribution or at
198       <https://www.openssl.org/source/license.html>.
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2021.1.1k                            2021-03-26                    SSL_CTX_NEW(3)