SSL_CTX_new -- create a new SSL_CTX object as framework for TLS/SSL enabled functions
Synopsis
#include <openssl/ssl.h>
SSL_CTX *SSL_CTX_new(const SSL_METHOD *method);
DESCRIPTION
SSL_CTX_new() creates a new SSL_CTX
object as framework to establish TLS/SSL enabled connections.
NOTES
The SSL_CTX object uses 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.
method can be of the following
types:
A TLS/SSL connection established with these methods will only
understand the SSLv2 protocol. A client will send out SSLv2
client hello messages and will also indicate that it only
understand SSLv2. A server will only understand SSLv2 client
hello messages.
A TLS/SSL connection established with these methods will only
understand the SSLv3 protocol. A client will send out SSLv3
client hello messages and will indicate that it only
understands SSLv3. A server will only understand SSLv3 client
hello messages. This especially means, that it will not
understand SSLv2 client hello messages which are widely used
for compatibility reasons, see SSLv23_*_method().
A TLS/SSL connection established with these methods will only
understand the TLSv1 protocol. A client will send out TLSv1
client hello messages and will indicate that it only
understands TLSv1. A server will only understand TLSv1 client
hello messages. This especially means, that it will not
understand SSLv2 client hello messages which are widely used
for compatibility reasons, see SSLv23_*_method(). It will
also not understand SSLv3 client hello messages.
A TLS/SSL connection established with these methods will
understand the SSLv2, SSLv3, and TLSv1 protocol. A client
will send out SSLv2 client hello messages and will indicate
that it also understands SSLv3 and TLSv1. A server will
understand SSLv2, SSLv3, and TLSv1 client hello messages.
This is the best choice when compatibility is a concern.
The list of protocols available can later be limited using the
SSL_OP_NO_SSLv2, SSL_OP_NO_SSLv3, SSL_OP_NO_TLSv1 options of the
SSL_CTX_set_options() or SSL_set_options() functions. Using these
options it is possible to choose e.g. SSLv23_server_method() and be
able to negotiate with all possible clients, but to only allow newer
protocols like SSLv3 or TLSv1.
SSL_CTX_new() initializes the list of ciphers, the session cache
setting, the callbacks, the keys and certificates, and the options to
its default values.
RETURN VALUES
The following return values can occur:
NULL
The creation of a new SSL_CTX object failed. Check the error
stack to find out the reason.
Pointer to an SSL_CTX object
The return value points to an allocated SSL_CTX object.
