NAME
SSL_CTX_set_tlsext_status_cb,
SSL_CTX_get_tlsext_status_cb,
SSL_CTX_set_tlsext_status_arg,
SSL_CTX_get_tlsext_status_arg,
SSL_set_tlsext_status_type,
SSL_get_tlsext_status_type,
SSL_get_tlsext_status_ocsp_resp,
SSL_set_tlsext_status_ocsp_resp —
OCSP Certificate Status Request
functions
SYNOPSIS
#include
<openssl/tls1.h>
long
SSL_CTX_set_tlsext_status_cb(SSL_CTX
*ctx, int (*callback)(SSL *, void *));
long
SSL_CTX_get_tlsext_status_cb(SSL_CTX
*ctx, int (*callback)(SSL *, void *));
long
SSL_CTX_set_tlsext_status_arg(SSL_CTX
*ctx, void *arg);
long
SSL_CTX_get_tlsext_status_arg(SSL_CTX
*ctx, void **arg);
long
SSL_set_tlsext_status_type(SSL
*s, int type);
long
SSL_get_tlsext_status_type(SSL
*s);
long
SSL_get_tlsext_status_ocsp_resp(ssl,
unsigned char **resp);
long
SSL_set_tlsext_status_ocsp_resp(ssl,
unsigned char *resp, int
len);
DESCRIPTION
A client application may request that a server send back an OCSP
status response (also known as OCSP stapling). To do so the client should
call the
SSL_set_tlsext_status_type()
function on an individual SSL object prior to the
start of the handshake. Currently the only supported type is
TLSEXT_STATUSTYPE_ocsp. This value should be passed
in the type argument.
The client should additionally
provide a callback function to decide what to do with the returned OCSP
response by calling
SSL_CTX_set_tlsext_status_cb().
The callback function should determine whether the returned OCSP response is
acceptable or not. The callback will be passed as an argument the value
previously set via a call to
SSL_CTX_set_tlsext_status_arg().
Note that the callback will not be called in the event of a handshake where
session resumption occurs (because there are no Certificates exchanged in
such a handshake).
The callback previously set
via
SSL_CTX_set_tlsext_status_cb()
can be retrieved by calling
SSL_CTX_get_tlsext_status_cb(),
and the argument by calling
SSL_CTX_get_tlsext_status_arg().
On the client side,
SSL_get_tlsext_status_type()
can be used to determine whether the client has previously called
SSL_set_tlsext_status_type(). It will return
TLSEXT_STATUSTYPE_ocsp if it has been called or -1
otherwise. On the server side,
SSL_get_tlsext_status_type() can be used to
determine whether the client requested OCSP stapling. If the client
requested it, then this function will return
TLSEXT_STATUSTYPE_ocsp, or -1 otherwise.
The response returned by the
server can be obtained via a call to
SSL_get_tlsext_status_ocsp_resp().
The value *resp will be updated to point to the OCSP
response data and the return value will be the length of that data. If the
server has not provided any response data, then *resp
will be NULL and the return value from
SSL_get_tlsext_status_ocsp_resp() will be -1.
A server application must also
call the
SSL_CTX_set_tlsext_status_cb()
function if it wants to be able to provide clients with OCSP Certificate
Status responses. Typically the server callback would obtain the server
certificate that is being sent back to the client via a call to
SSL_get_certificate(3), obtain the OCSP response to be sent
back, and then set that response data by calling
SSL_set_tlsext_status_ocsp_resp().
A pointer to the response data should be provided in the
resp argument, and the length of that data should be
in the len argument.
RETURN VALUES
The callback when used on the client side should return a negative value on error, 0 if the response is not acceptable (in which case the handshake will fail), or a positive value if it is acceptable.
The callback when used on the server side should return with
either SSL_TLSEXT_ERR_OK (meaning that the OCSP
response that has been set should be returned),
SSL_TLSEXT_ERR_NOACK (meaning that an OCSP response
should not be returned), or
SSL_TLSEXT_ERR_ALERT_FATAL (meaning that a fatal
error has occurred).
SSL_CTX_set_tlsext_status_cb(),
SSL_CTX_get_tlsext_status_cb(),
SSL_CTX_set_tlsext_status_arg(),
SSL_CTX_get_tlsext_status_arg(),
SSL_set_tlsext_status_type(), and
SSL_set_tlsext_status_ocsp_resp() always return 1,
indicating success.
SSL_get_tlsext_status_type() returns
TLSEXT_STATUSTYPE_ocsp on the client side if
SSL_set_tlsext_status_type() was previously called,
or on the server side if the client requested OCSP stapling. Otherwise -1 is
returned.
SSL_get_tlsext_status_ocsp_resp() returns
the length of the OCSP response data or -1 if there is no OCSP response
data.
SEE ALSO
HISTORY
SSL_CTX_set_tlsext_status_cb(),
SSL_CTX_set_tlsext_status_arg(),
SSL_set_tlsext_status_type(),
SSL_get_tlsext_status_ocsp_resp(), and
SSL_set_tlsext_status_ocsp_resp() first appeared in
OpenSSL 0.9.8h and have been available since OpenBSD
4.5.
SSL_CTX_get_tlsext_status_cb() and
SSL_CTX_get_tlsext_status_arg() first appeared in
OpenSSL 1.1.0 and have been available since OpenBSD
6.3.
SSL_get_tlsext_status_type() first
appeared in OpenSSL 1.1.0 and has been available since
OpenBSD 7.0.