NAME¶
SSL_CTX_set_tlsext_status_cb, SSL_CTX_set_tlsext_status_arg,
SSL_set_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_set_tlsext_status_arg(SSL_CTX *ctx, void *arg);
long SSL_set_tlsext_status_type(SSL *s, int type);
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 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 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. Typically a callback would obtain an OCSP_RESPONSE object
from this data via a call to the
d2i_OCSP_RESPONSE() function. 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(); 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_set_tlsext_status_arg(),
SSL_set_tlsext_status_type() and
SSL_set_tlsext_status_ocsp_resp() return 0 on error or 1 on success.
SSL_get_tlsext_status_ocsp_resp() returns the length of the OCSP response
data or -1 if there is no OCSP response data.