mirror of
https://github.com/openssl/openssl.git
synced 2024-12-09 05:51:54 +08:00
207 lines
7.1 KiB
Plaintext
207 lines
7.1 KiB
Plaintext
=pod
|
|
|
|
=head1 NAME
|
|
|
|
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);
|
|
void 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);
|
|
|
|
#define SSLv23_method TLS_method
|
|
#define SSLv23_server_method TLS_server_method
|
|
#define SSLv23_client_method TLS_client_method
|
|
|
|
#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
|
|
LSSL_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.
|
|
|
|
=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)>
|
|
|
|
=cut
|