SSL_CTX_new(3) | OpenSSL | SSL_CTX_new(3) |
#include <openssl/ssl.h> SSL_CTX *SSL_CTX_new_ex(OSSL_LIB_CTX *libctx, const char *propq, const SSL_METHOD *method); 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
SSL_CTX_new() does the same as SSL_CTX_new_ex() except that the default library context is used and no property query string is specified.
An SSL_CTX object is reference counted. Creating an SSL_CTX object for the first time increments the reference count. Freeing the SSL_CTX (using SSL_CTX_free) decrements it. When the reference count drops to zero, any memory or resources allocated to the SSL_CTX object are freed. SSL_CTX_up_ref() increments the reference count for an existing SSL_CTX structure.
An SSL_CTX object should not be changed after it is used to create any SSL objects or from multiple threads concurrently, since the implementation does not provide serialization of access for these cases.
The SSL_CTX object uses method as the connection method. Three method variants are available: a generic method (for either client or server use), a server-only method, and a client-only method.
The method parameter of SSL_CTX_new_ex() and SSL_CTX_new() can be one of the following:
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 version-flexible methods. All other methods only support one specific protocol version. Use the 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 SSL_CTX_set_min_proto_version(3), SSL_set_min_proto_version(3), SSL_CTX_set_max_proto_version(3) and 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, TLS 1.2 or TLS 1.3.
The list of protocols available can also be limited using the SSL_OP_NO_SSLv3, SSL_OP_NO_TLSv1, SSL_OP_NO_TLSv1_1, SSL_OP_NO_TLSv1_3, SSL_OP_NO_TLSv1_2 and SSL_OP_NO_TLSv1_3 options of the SSL_CTX_set_options(3) or 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 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 SSL_CTX_set_min_proto_version(3) to set the minimum protocol to at least TLS1_VERSION.
SSL_CTX_up_ref() returns 1 for success and 0 for failure.
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 added in OpenSSL 1.1.0.
All version-specific methods were deprecated in OpenSSL 1.1.0.
SSL_CTX_new_ex() was added in OpenSSL 3.0.
Licensed under the Apache License 2.0 (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 <https://www.openssl.org/source/license.html>.
2023-10-25 | 3.0.12 |